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Conference Sponsors: Design Engineering Division, Computers and Information in Engineering Division
This online compilation of papers from the ASME 2014 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference (IDETC/CIE2014) represents the archival version of the Conference Proceedings. According to ASME's conference presenter attendance policy, if a paper is not presented at the Conference, the paper will not be published in the official archival Proceedings, which are registered with the Library of Congress and are submitted for abstracting and indexing. The paper also will not be published in The ASME Digital Collection and may not be cited as a published paper.
Centrifugally operated friction clutches, named DM clutch in this paper, had been developed to couple an engine to an inputshaft of a mechanical transmission for commercial vehicles [1]. The DM clutch based AMT (automated mechanical transmission) has been in production from Eaton for more than a decade in the North American commercial vehicle market. Its working principle is to take advantage of the centrifugal force of sliding masses between two clutch plates to complete the transitions among unlock, slipping and lockup. DM clutch is reliable and durable, but not easy to modulate because of involvement of engine speed controls, nonlinear friction forces and variable vehicle loads. One challenging aspect is the occurrence of torsional vibrations during vehicle launches. In this paper, a friction based damping control strategy [2, 3] utilizing the frictional characteristics is shown to control the DM clutch to achieve smoother vehicle launch. The vehicle testing data shows its effectiveness of smoothening the vehicle launches with and without the loaded trailer under different operational conditions.
EcoCAR 2: Plugging into the Future is an Advanced Vehicle Technology Competition managed by the U.S. Department of Energy at Argonne National Laboratory. The competition challenges 15 universities across North America to reduce the environmental impact of a production vehicle without compromising performance, safety and consumer acceptability. To meet this goal, the Pennsylvania State University Advanced Vehicle Team has designed a series plug-in hybrid electric vehicle (PHEV) capable of achieving a 40 mile all-electric range. An auxiliary power unit (750 cc two-cylinder engine converted to run on E85 fuel) provides extended range greater than 200 miles. A rigorous development process has been followed to provide a control system that meets the safety, performance and fuel economy targets, including fault mitigation.
This paper summarizes the control system development strategy, starting with vehicle component selection. The strategies used to develop a control algorithm and plant model in parallel are described. Extensive testing is performed throughout the vehicle development process, including both software-in-the-loop (SiL), hardware-in-the-loop (HiL), and in-vehicle testing. In addition, it will be shown how pertinent testing data plays a crucial role in further plant model developments.
In this paper, an investigation is performed into the optimization of wheel power distribution between the drive axles of an AWD hybrid-electric SUV. The paper presents a criterion to maximize the vehicle's slip efficiency through control of the kinematic discrepancy factor. The optimization criterion is combined with a mathematical model of a driveline for an AWD hybrid-electric vehicle using a new hybrid-electric power transmitting unit to control power distribution between the front and rear drive wheels. A technical concept is described for the hybrid-electric power transmitting unit that is functionally fused with a series hybrid-electric transmission. The mode of operation of the power transmitting device is described and simulations are performed for a 4×4 hybrid-electric vehicle of different driveline characteristics to compare the influence of driveline type on vehicle energy efficiency, including battery depletion, and vehicle mobility when traveling on a road or off-road under severe terrain conditions.
In last decades hybrid and electric vehicles have been one of the main object of study for automotive industry. Among the different layout of the electric power-train, four in-wheel motors appear to be one of the most attractive. This configuration in fact has several advantages in terms of inner room increase and mass distribution. Furthermore the possibility of independently distribute braking and driving torques on the wheels allows to generate a yaw moment able to improve vehicle handling (torque vectoring). In this paper a torque vectoring control strategy for an electric vehicle with four in-wheel motors is presented. The control strategy is constituted of a steady-state contribution to enhance vehicle handling performances and a transient contribution to increase vehicle lateral stability during limit manoeuvres. Performances of the control logic are evaluated by means of numerical simulations of open and closed loop manoeuvres. Robustness to friction coefficient changes is analysed.
A hybrid-electric vehicle powertrain architecture consists of single or multiple driving modes, i.e., connection arrangements among engine, motors and vehicle output shaft that determine distribution of power. While most architecture development work to date has focused primarily on passenger cars, interest has been growing in exploring architectures for special-purpose vehicles such as vans or trucks for civilian and military applications, whose weights or payloads can vary significantly during operations. Previous findings show that the optimal architecture can be sensitive to vehicle weight. In this paper we investigate architecture design under a distribution of vehicle weights, using a simulation-based design optimization strategy with nested supervisory optimal control and accounting for powertrain complexity. Results show that an architecture under a single load has significant differences and lower fuel efficiency than an architecture designed to work under a variety of loading scenarios.
The increase of energy efficiency of vehicles in the course of rising energy costs and the limited range of electric vehicles can be realized with ecological driver assistance systems. Based on preview information these systems can assist the driver in providing energy efficient driving and operating strategies. But, many of these systems directly focus on specific functional approaches and do not consider a comprehensive system architecture. Thus, functional extensions and adoptions to other vehicle and propulsion concepts are hereby complicated.
In this paper a generic system architecture is introduced which represents a framework for present and future for assistance systems for ecological optimization. The framework provides hereby the overview of the necessary core modules and the interfaces between them. The innovative aspect of the introduced framework is the modularization in a vehicle independent optimization module and a vehicle dependent energy conversion model. This approach promotes a vehicle independent and efficient system development. The system architecture aims to provide a basis for assistance systems that are robust towards functional extensions and adoptions to other vehicle and propulsion concepts.
In an exemplary use case the application of the generic system architecture is demonstrated and the portability is discussed.
This paper presents a feasibility study of a method for turbocharging single cylinder, four-stroke internal combustion engines. Turbocharging is not conventionally used with single cylinder engines because of the timing mismatch between when the turbo is powered, during the exhaust stroke, and when it can deliver air to the cylinder, during the intake stroke. The proposed solution involves an air capacitor on the intake side of the engine between the turbocharger and intake valves. The capacitor acts as a buffer and would be implemented as a new style of intake manifold with a larger volume than traditional systems.
In order for the air capacitor to be practical, it needs to be sized large enough to maintain the turbocharger pressure during the intake stroke, cause minimal turbo lag, and significantly increase the density of the intake air. By creating multiple flow models of air through the turbocharged engine system, we found that the optimal size air capacitor is between four and five times the engine capacity. For a capacitor sized for a one-liter engine, the lag time was found to be approximately two seconds, which would be acceptable for slowly accelerating applications such as tractors, or steady state applications such as generators. The density increase that can be achieved in the capacitor, compared to air at standard ambient temperature and pressure, was found to vary between fifty percent for adiabatic compression and no heat transfer from the capacitor, to eighty percent for perfect heat transfer. These increases in density are proportional to, to first order, the anticipated power increases that could be realized with a turbocharger and air capacitor system applied to a single cylinder, four-stroke engine.
Hardware-in-the-loop (HIL) platforms enable rapid evaluation of different system configurations and energy management strategies for electrified/hybrid powertrains without building full vehicle prototypes. This paper outlines a HIL platform for a series hybrid powertrain and discusses particular control strategies. The main hardware components of the platform are a gasoline generator, a lead acid battery pack, a bi-directional dc/dc converter, a programmable dc load, strain gauges, and a rotary encoder. Along with these hardware components, a real-time control prototyping system is used to implement energy management strategies and monitor several signals form the HIL platform. The effectiveness and performance of this platform is demonstrated by implementing two versions of the Equivalent Consumption Minimization Strategy (ECMS). The first version uses a constant equivalence factor for weighting the cost of electrical energy storage, while the second version uses an adaptive equivalence factor based on the deviation of battery state of charge (SOC) from a reference SOC.
With gas prices and pollution on the rise, the production of electric and hybrid-electric vehicles has been a focus of all major automobile manufacturers. The further advancement of this technology must not only continue to focus on fuel-efficient, low-emission vehicles, but also decrease their cost to make them more available and enticing to the general public.
Results from this research include one potential solution to reduce the cost of electric and hybrid-electric vehicles. An exploration of the functionality of a Planetary Differential (PD) has shown that it can simplify expensive and complex electronic control systems for electric and hybrid-electric vehicles. This research is a furtherance of work performed previously and its main purpose is to discover a more efficient solution than what was already tested under similar circumstances. Recommendations for future work and implementation of the PD in electric and hybrid-electric vehicles are presented herein.
The Distributed Electro-hydraulic Braking system (DEHB) is a wet type brake-by-wire system. As a safety critical automotive electrical and/or electronic (E/E) system, DEHB shall be designed under the guideline of ISO 26262 in order to avoid unreasonable risk due to the malfunctions in the item. This paper explores how the Automotive Safety Integrity Level (ASIL) decomposition in the concept phase is influenced by the system architectures of DEHB. Based on a typical hazardous event, analysis on DEHB with the same system architecture as the Electro-mechanical Braking system (EMB) is carried out, which is taken as the basis for comparison. Two types of DEHB with different system architectures are then analyzed. Results show that the adoption of hydraulic backup enables ASIL decomposition in the pedal unit. The adoption of both hydraulic backup and normally open balance valves offers the opportunity to perform ASIL decomposition in the brake actuator system of DEHB.
Pedestrians are among the most vulnerable participants in current city traffic. While in the past original equipment manufacturers (OEMs, in meanings of carmakers) mainly focused on passenger safety, nowadays strict legislation requirements call for the development of more effective pedestrian safety concepts. Considerations for constructive and technological road safety measures generally take place in a company-specific product development process, but mainly in phases, that do not allow for innovative products in terms of new solutions. Thus, the importance of early development phases as well as design process models, such as Pahl and Beitz, will be described here. Also the significance of the development design cases will be handled, as they can mainly influence the innovation degree of the resulting products. In the end an approach will be introduced, of how an analysis of product models regarding their possibilities for adequate evaluation can help, to support a safety-related development process by integrating suitable design methods and tools.
New vehicles are currently being developed to transport crews to space by NASA and several commercial companies. During the takeoff and landing phase, vehicle occupants are typically exposed to spinal and frontal loading. To reduce the risk of injuries during these common impact scenarios, NASA has begun research to develop new safety standards for spaceflight. The THOR, an advanced multi-directional crash test dummy, was chosen by NASA to evaluate occupant spacecraft safety due to its improved biofidelity.
Recently, a series of modifications were completed by the National Highway Traffic Safety Administration (NHTSA) to improve the bio-fidelity of the THOR dummy. The updated THOR Modification Kit (THOR-K) dummy was tested at Wright-Patterson (WP) Air Base in various impact configurations, including frontal and spinal loading. A computational finite element (FE) model of the THOR was developed in LS-DYNA software and was recently updated to match the latest dummy modifications. The main goal of this study was to calibrate and validate the FE model of the THOR-K dummy for use in future spacecraft safety studies.
An optimization-based method was developed to calibrate the material properties of the pelvic flesh model under quasi-static and dynamic loading conditions. Data in a simple compression test of pelvic flesh were used for the quasi-static calibration. The whole dummy kinematic and kinetic response under spinal loading conditions was used for the dynamic calibration. The performance of the calibrated dummy model was evaluated by simulating a separate dummy test with a different crash pulse along the spinal direction. In addition, a frontal dummy test was also simulated with the calibrated model. The model response was compared with test data by calculating its correlation score using the CORA rating system.
Overall, the calibrated THOR-K dummy model responded with high similarity to the physical dummy in all validation tests. Therefore, confidence is provided in the dummy model for use in predicting response in other test conditions such as those observed in the spacecraft landing.
Ride comfort is an important aspect of any passenger vehicle. The challenge is to provide a comfortable, yet safe, ride for the driver and the passengers and there is often a trade-off between ride comfort and safety performance.
In the case of small wheelchair-accessible vehicles the challenge increases. The weight of a wheelchair with person may span from 50 kg to 500 kg, which means that the suspension must be tuned to have a broad working range. Also, a wheelchair-accessible vehicle has many restrictions on design space and tuning possibilities due to, e.g., the space needed for the wheelchair passenger to get in and out of the vehicle. Hence, there is an additional need to evalute ride comfort and performance before the vehicle is built in order to find the optimal design. Traditionally, this is done by computer simulations of vehicle handling complemented with testing followed by chassis tuning prior to production. However, some performance parameters regarding comfort, especially in the case of wheelchair passengers, are still not well investigated and documented, and there is a need to subjectively evaluate the ride comfort in early design phases.
In this paper we investigate the use of a motionbase simulator as a platform for evaluating ride comfort with different suspension setups. We are using a reversible sleeve air suspension bellow equipped with an adaptor cylinder giving the spring characteristics. The characteristics of four different adaptors have been measured in a universal test machine. The force-compression characteristics are imported into the simulation. The simulation model used is a half-car, two-degree of freedom producing bounce and pitch movement data for either the driver or the passenger positions. The data from the simulations are used as input to a motionbase simulator for subjective assessment of the ride comfort.
The primary results indicate that a motionbase simulator can be a useful tool when designing/developing suspension systems. Also, the results indicate that a motionbase simulator is useful for investigation of comfort parameters in order to determine objective assessment of subjective parameters.
Thin-walled beams with open-section are extensively employed as energy absorption structures in transportation system, e.g., automobile bumper beams and guardrails. However, during the crushing process of these traditional open-section structures, local section flattening and lateral buckling of the webs always occur, which lead to a reduction on section-height, resulting in a significantly smaller bending resistance at the later stage of deformation and the formation of localized plastic hinges. This paper presents a novel design of high performance energy absorption beams using developable origami patterns. The origami beams overcome the problems associated with traditional open-section structures and they give nearly constant bending resistance during crushing process. Numerical analysis shows that the specific energy absorption (energy absorption per unit mass) of the origami beam is at least 20% higher in large deformation than that of the traditional thrie-beam which often used as guardrail. Our research finding demonstrates that utilising origami patterns to open-section beams can effectively alter their collapse modes, attain nearly constant bending resistance and achieve higher specific energy absorption.
Multi-wheeled combat vehicles behavior depends not only on the available total driving torque but also on its distribution among the drive axles/wheels. In turn, this distribution is largely regulated by the drivetrain layout and its torque distribution devices.
In this paper, a multi-wheeled (8×4) combat vehicle bicycle model has been developed and used to obtain the desired yaw rate and lateral acceleration to become reference for the design of the controllers. PID controllers were designed as upper and lower layers of the controllers. The upper controller develops the corrective yaw moment, which is the input to the lower controller to manage the independent torque distribution (torque vectoring) among the driving wheels. Several simulation maneuvers have been performed at different vehicle speeds using Matlab/Simulink-TruckSim to investigate the proposed torque vectoring control strategy. The simulation results with the proposed controller showed a significant improvement over conventional driveline, especially at severe maneuvers.
The developed Active Front Steering (AFS) Linear Time Variant (LTV) Model Predictive Control (MPC) is a linear model predictive control based on linearization of the nonlinear vehicle model. A sensitivity analysis of the parameters of the controller is carried out on a simple path following test. Once the optimal parameters are found, both in terms of trajectory following and real-time performances, the LTV-MPC is used for determining the requirements for the necessary sensors (in terms of minimum obstacle distance detection) as a function of the vehicle speed. Then, the same analysis is carried out considering wet road conditions (i.e. the tyre-road friction coefficient is different from that accounted for by the controller).
The use of controllable semi-active damping is considered by the vehicle dynamics community to be a cost effective and fail-safe method to reduce the ride comfort and handling tradeoff of a vehicle. This paper investigates the semi-active control of a suspension system for a 4-wheeled single seated off-road vehicle for both ride comfort and handling. The test vehicle is distinct with several characteristics that are not commonly observed on normal vehicles or addressed in existing literature. For instance, the absence of a differential in the driveline causes drivability and handling issues that are aggravated by increased damping. The suspension system contains controllable dampers and passive hydro-pneumatic spring-damper units. Passive damping is not entirely eliminated from the suspension, but the effect of various passive damping factors on the performance of the suspension is also investigated. Skyhook and groundhook control is implemented on a nonlinear, three-dimensional, 12 degrees of freedom simulation model to determine the achievable improvement in ride comfort and handling ability of the test vehicle. Simulation results show that reduced passive damping is capable of improving both the ride comfort and maneuverability of the test vehicle.
In this paper, we address the enhanced state estimation and prediction system for automobile applications by fusing relatively low-cost and noisy Inertial Navigation System (INS) sensing with Global Positioning System (GPS) measurements. An unscented Kalman filter is used to merge multi-rate measurements from GPS and INS sensors together with a high-fidelity vehicle-dynamics model for state-predictions. The high-fidelity motion model (including suspension-effects) for the vehicle motion trajectory on uneven terrain is captured by a 20-state system of nonlinear differential equations. Computer simulation results illustrate the effectiveness of sensor-fusion (building upon the merger of an inexpensive INS sensing with GPS based measurements) to accurately estimate the full system-state. The relative ease of implementation, accuracy and predictive performance with low-cost sensing will facilitate its use in various electronic control and safety-systems, such as Electronic Stability Program, Anti-lock Brake Systems, and the Lateral Dynamic Stability Control.
One of the technical problems in wheel dynamics is to establish and control the relationship between the tire kinematic and force characteristics related to tire slippage and thus to tire-soil power losses and wheel mobility estimation. This problem has been attracting a lot attention from the research community for decades. The electronization of modern vehicles can enhance their performance in complex and severe vehicle-road/terrain environments by implementing agile control decision within the scale of milliseconds. Thus, agility requires new approaches when considering and analyzing the tire slippage process.
This paper presents an analysis of the tire slippage process in stochastic terrain conditions for the purpose of agile tire slip modeling, estimation and control. Based on the introduced relations between the rolling radii of the tire, circumferential wheel force/wheel torque, wheel kinematic parameters and tire slippage, a set of agile tire-terrain characteristics is offered in the paper. The proposed characteristics take in consideration the rate of change of the listed parameters and thus allow a user to estimate the agile dynamics of the tire slip and evidence the closeness to the peak friction coefficient and hence estimate potential mobility loss. The characteristics establish relationships between the stochastic peak friction coefficient, rolling resistance coefficient, and wheel kinematic/force parameters. The characteristics are illustrated by computer simulation results in several terrain conditions.
The paper presents an analysis of holonomic and non-holonomic material/non-material constrains that may be used in wheeled vehicle dynamics. Based on this analysis, a modified approach to the formulation of vehicle motion constraints is proposed. Specifically, a non-material constraint that limits vehicle kinematic parameters to a required motion, i.e. to a programmable motion that corresponds to required vehicle operational properties including turnability and stability of motion, is introduced.
The new concept of constraints put upon wheeled vehicle dynamics makes the resulting direct and inverse dynamic models more oriented towards required vehicle performance and facilitate the control design. The new constraint concept is illustrated by an example of a required vehicle acceleration performance.
The chassis of light commercial vehicle (LCV) could be used for creating a wide range of vehicles modifications with the similar base (chassis), but really different performance in wide range of maneuvers. The differences could be explained by variety of design parameters. It means that the design of LCV modifications needs some effective approach that will provide an engineer by necessary data that could help to estimate the performance of new vehicles in particular active safety characteristics. This paper presents the combination of experimental and simulation methods that could be used for estimation of LCV active safety characteristics (first of all cornering stability). The experimental method of estimation of cornering stability is shown that is based on regulations of the Russian Standard GOST R 52302-2004 that presuppose different types of testing: static rollover and dynamic maneuvering on a road (line changing and running into the corner). The multi-body simulation method with using of MSC.ADAMS/CAR software was also used in a study. The approval of developed LCV multi-body model was made on a basis of good correlation between simulation results and experimental data. The relationship between LCVs design parameters (axle load distribution, height of the center of gravity, vertical and angular suspension stiffness) and active safety characteristics are received.
This paper proposes and demonstrates a cascaded predictive control strategy that quantifies and uses longitudinal and lateral tire force saturation for directional stability control of road vehicles. Saturation is explicitly defined and computed as the deficiency of a tire to generate a linearly increasing force in either the lateral or longitudinal direction. The optimal management of lateral saturation levels is set as the objective for an upper level controller, while the optimal management of longitudinal saturation among all tires is set as the objective for a lower level driving/braking torque distribution controller. This cascaded predictive scheme exploits prevailing time scale separations between the lateral vehicle dynamics and the tire/wheel dynamics. The performance of the approach is illustrated using simulations of a medium-duty truck undergoing a transient handling maneuver.
Stochastic modeling for mobility estimation has vastly improved through recent research and the advancements in technology, but those advancements haven't fully been applied to full vehicle mobility control and on-line (real time) analysis of each driving wheel's contribution and influence.
This paper presents an analysis of fundamental mobility dynamics implemented into advanced stochastic estimation methodologies. Based on this analysis, the paper formulates: (i) developed on-line mobility criteria in stochastic conditions from one wheel to full vehicle with six driving wheels in which the contribution of every wheel can be estimated, and (ii) terrain characterization and agile vehicle dynamics information to estimate UGV mobility in real time.
This analysis enables on-line mobility estimation for UGVs to make control changes as the event of poor terrain conditions occur (or before it) rather than after the event, causing the vehicle to then optimize its reaction to regain control. These fundamental applications for mobility control in stochastic conditions enable today's one wheel modeling solutions to be applied to the full vehicle.
The specifications of ground vehicles considering requirements like maneuverability and footprint are mainly caused by the target traffic. Future population distribution is subject to rural exodus resulting in megacities with the corresponding rise of traffic density and immense parking-space shortage. The problems caused by the compromise between a small footprint due to traffic requirements and a large one due to safety reasons are well known by the automotive industry as urban concept cars from different automobile exhibitions attest [1] [2] [3] [4] [5] [6] [7]. One of the known approaches is active tilt as it seems to be promising to reduce the vehicle's dimension while coping with lateral acceleration demand and roll-over safety [4] [7]. But, active tilt represents only one solution for a situational adaptive chassis.
The proposed paper analyzes two alternative concepts, a variable track width and a variable height of the CG, and compares them to the known active tilt principle [8]. By using the exemplary maneuver of "steady-state cornering" the potential of each function concerning an increase of maneuverability and a decrease of the footprint is investigated. The results are promising and justify further investigation on the subject as for example dynamic simulation which has not been part of the study. The presented analytical examination of the influence on the yaw velocity gain and roll-over safety may open the discussion about the chances and risks of variable chassis design.
We present a specialized multibody joint that constrains motion to a spatial path. The joint is used in the reduction of 1 degree-of-freedom systems with complex kinematics. Example applications of the joint are: the reduction of vehicle suspension systems, or the representation of biological joints. The new joint is implemented in the graph-theoretic symbolic multibody modeling environment of MapleSim and is formulated in such a way that a single ordinary differential equation is used to describe the resulting kinematic pair. A particle moving along a planar semi-circular path was chosen as the first example for successful validation of the new joint since a simple closed-form solution in terms of the path length exists. To represent arbitrary curves, the path must first be parameterized in terms of its path length. Next, a differentiable mathematical definition of the curve must be generated. B-splines are generated to define the path. For best performance we minimize the number of knots in the splines and find their optimal locations. Using the spline fitting approach, a planar parabolic path is generated and used to further analyze the performance of our implementation.
The TowPlow is a novel type of snowplow that consists of a conventional snowplow vehicle and a steerable, plow-mounted trailer. The trailer is equipped with hydraulic-powered steerable axles so that it can be steered up to 30 degrees with respect to the tractor. The combination of the front plow of the towing snowplow and the trailer-equipped plow is able to clear a path up to approximately 24-ft wide, which is the width of two typical traffic lanes. In this paper, the kinematic characteristics of the TowPlow are derived using instantaneous centers of velocity. Based on the derived equations, the relation between the radius of curvature and the trailer wheel steering angle that allows the tractor-trailer to maintain its initial articulation angle is defined. Also, simulations of constant radius turning are performed with and without the trailer's corrective steering, and the results are compared. Even though the kinematic analysis does not take forces and inertia into account, it is clearly demonstrated in the simulation results that appropriate steering of the trailer wheel is necessary to maintain the articulation angle of the TowPlow and to prevent the device from intruding into adjacent lanes.
A new framework is developed in this paper for the efficient implementation of semi-empirical terramechanics models in multibody dynamics environments. In this approach, for every wheel in contact with soft soil, unilateral contact constraints are added to the solver in both the normal direction and the tangent plane. The forces associated with the tangent plane, like traction and rolling resistance, are formulated in this approach as set-valued functions, whose properties are determined by deregularization of the above-mentioned terramechanics relations. As shown in this paper, this leads to the dynamics representation in the form of a linear complementarity problem (LCP). With this formulation, stable simulation of rovers is achieved even with relatively large time steps. In addition, a high-resolution height-field is employed to model terrain-surface deformations and changes in hardening of soil under the wheel. As a result, the multi-pass effect is also captured in our approach. In addition, an extensive set of experiments was conducted using a version of the Juno rover (Juno II). The experimental results are analyzed and compared with the model developed in the paper.
Tire blowout is one of the most dangerous tire malfunctions which could result in severe property damage, personal injury, even loss of life. In the existing literatures, active tire blowout fail-safe control strategies based on rules or optimal control have been proposed. However, little attention has been put on driver behavior, which plays an important role in the stability performance control when tire blowout is experienced. Because of the uncertainties of failure mode and failure level, most of existing active control strategies are not easy to be implemented. This paper presents the research work on stability control for tire blowout vehicle, considering the driver behavior at the emergent scenario. The Electro Hydraulic Brake (EHB) based Brake by Wire (BBW) system is used as the brake system, which can regulate the wheel brake force individually and accurately. The simulation results show that stability and brake efficiency can be achieved in tire blowout fail-safe control by combining the driver operation model and BBW.
Military vehicles have been experiencing high rollover rates over the last few years of deployment. There have been several hundred rollovers, of which approximately fifty percent are categorized as fall based. Fall based rollover occurs when the road gives way underneath the vehicle on one side as the soil is unable to support the vehicle load. To reduce fatalities, a real-time driving simulator can be used to simulate fall-based rollover for the driver training as well as for validating the effectiveness of advanced suspension technologies. The driver training can help prepare drivers with the varying degrees of terrain difficulties, by applying optimal steering and speed strategies in a simulated environment. The fall-based rollover occurs mainly due to combination of the tire sinkage and the lateral bulldozing. In the current research, equations for the tire-soil model are developed based on the Bekker's equations and Mohr-Coulomb equations that compute the tire sinkage into the soil, the lateral and longitudinal forces from the soil deformation, rolling resistance due to the soil compaction, and the lateral plowing effects. The tire-soil model is incorporated into a commercial real-time multi-body code to simulate fall-based rollovers for various slopes and soil conditions. Results indicate rollover propensity changes depending the type of soil and the steering strategy used.
Stability of two-wheeled vehicles is influenced by the transient properties of tires, which are described in terms of the relaxation length, which is the distance that the vehicle travels before tire forces reach the steady state values. Relaxation length is often studied by means of rigid ring models, in which the belt of the tire is modeled as a rigid ring elastically connected to the rim and the contact patch is connected to the belt by means of residual springs. Actually these models are able to take into account the lateral and the diametrical modes of vibration of the rigid belt with respect to the rim and to represent in a simplified way the modes with belt deformation by means of the residual stiffness. Experimental tests are needed to find the parameters of the models and to validate results. This research focuses on the relaxation length of side-slip force and aims to improve knowledge in this field, since there is no consolidated method for deriving the parameters of rigid ring models and, especially in two-wheeled vehicles, the relevance of rigid belt and deformable belt modes is not well known. Experimental tests are performed on a rotating disk machine developed for testing tires of two-wheeled vehicles, two motorcycle and two scooter tires are considered. Transient properties are studied by carrying out tests with harmonic variations of side-slip angle, since in the frequency domain the relaxation length corresponds to a phase lag between the input and tire force. Phase lags are measured and relaxation lengths are identified for a wide range of inflation pressures. Then each tire is modally tested and natural frequencies, dampings and vibration modes are found, the stiffnesses associated to the lateral and diametrical modes are identified. Finally a comparison is made between the identified relaxation length and the prediction given by a model based on the identified tire modes. The relevance of deformable belt modes is analyzed and their influence on relaxation length is discussed.
The concept and the embodiment design of a frame for a race motorcycle is addressed. The motorcycle is designed for the Moto3 World Championship. The aim is to develop a frame that could be eventually produced by die casting.
Given the basic geometry of the motorcycle and the engine dimensions, a multi-body model is derived by Modelica. The model is able to simulate the dynamic behaviour of the motorcycle in the two most critical conditions of use, namely braking and passing over a cleat. A comparison with experimental data has allowed the validation of the model.
By means of Optistruct, an optimized structure for the frame is proposed and compared to the one derived by an experienced designer. A technique is proposed for the computation of stresses in the frame that exploits, in an integrated manner, FEM and multi-body modeling. A fatigue analysis aimed at assessing the life of the frame is performed.
The combination of the most advanced modeling tools has enabled the design of a very light and stiff frame, additionally a process has been derived for future development of optimised motorcycle frames.
This paper discusses the modeling and analysis of a novel audio subwoofer system for automotive applications using the automobile windshield glass. The use of a piezo-electric actuator coupled with a mechanical amplifier linked to a large glass panel provides a highly efficient method of producing sound. The proposed subwoofer system has the advantage over existing conventional systems of not only reducing the weight of the automobile, but also a significant power savings resulting in an increase of expected fuel economy. Among various design challenges, the glass-sealing design is of huge importance, as it affects the system dynamic response and so the output sound characteristics. The main goal in this manuscript is to evaluate different glass-sealing design configurations by providing a comprehensive Finite Element model of the system. To do so, a comprehensive, yet simplified FE model is developed, and experimental studies are performed in the component level to fine-tune and verify the model. Harmonic response of the system for each sealing configuration design is obtained in the frequency range of 0–200 Hz, and the results are compared and discussed. The finite element model is also beneficial in preliminary design of other components as well as the exciter placement, and predicting the performance of the overall system.
Vibrational comfort is one of the most important parameters evaluated by cyclists and it is correlated to the response of bicycle components in combination with the cyclist's characteristics.
Vibration transmissibility of wheels and saddles had been recently studied during lab tests using a wooden dummy bottom resting on the saddle and in road tests on an instrumented racing bicycle at different speeds on different surfaces.
In this study, a test bench was developed in order to simulate different vibrational inputs to the seatpost from the road surface on a group of real cyclists during steady cycling. The bench is composed by a racing bicycle without wheels, hinged at the front fork axle and sustained by an hydraulic actuator connected to the seatpost. The bicycle is equipped with pedals and chain wheel and a long chain drives another rear wheel fixed to the bench and connected to brake rollers.
Three racing bicycle saddles were evaluated by a group of five cyclists after the application of vibrational spectra corresponding to PSDs recorded in the field tests: the magnitude of the transfer function H between the input vertical acceleration at the seatpost and the output acceleration at the pelvis was obtained by two accelerometers. The cyclists were in the meantime asked to fill a questionnaire regarding the perceived comfort of the three saddles during the tests.
Initial results showed an encouraging correlation of the subjective ranking of saddles with the corresponding Index of Transmissibility derived from the transfer function H.
The SOFIE project aims to improve the understanding of bicycle and rider stability in order to increase the safety of elderly cyclists. In the framework of this project, an advanced multi-body model of bicycle and rider dynamics, including the influences of the environment, is developed. The purpose of this model is to test, in the design phase, different concepts of so-called Intelligent Assist Devices (IADs) to enhance cycling safety. The model is validated in a novel experimental setup where under controlled and safe conditions the rider and bicycle can be perturbed to identify the properties of the control mechanisms.
In the setup the rear wheel of the instrumented bicycle rotates freely on a roller bench. The front wheel rotates on a treadmill to preserve the tire-road contact[9]; steering can still be used to maintain balance. The roller bench is situated on a 6 degrees of freedom Stewart platform. The movement of the platform can be controlled in each direction. Therefore, it is possible to apply disturbances to the roll, pitch and yaw and to apply lateral, posterior and superior disturbances to the bicycle with a predetermined multisine disturbance signal.
The bicycle is equipped with sufficient inertial sensors to accurately estimate the current orientations. Furthermore, the laboratory setup allows utilizing a marker-based video system to measure subject and bicycle movements in a global frame. The subject is secured in a safety harness. By analysing experiments in this setup in the mathematical model, the experiments may serve as validation data.
Preliminary results showed that it is well possible to perform perturbation experiments; the actual modelling of the tyre-floor contact proves important in determining the response. Further experiments will be done to estimate the properties of the control system in different categories of riders using system identification, allowing differences between young and elderly subjects to be studied. Subsequently, with the novel experimental setup it is possible to evaluate IADs.
Public transportation provides a crucial solution to economic, energy, and environmental challenges. Large passenger vehicles in public transportation, however, often cause more serious accidents than passenger cars. It is therefore critical to improve both the designs of large passenger vehicles and road safety facilities. This work develops a design methodology to minimize the accident damage of large passenger vehicle rollover against guardrails. The design improvement is based on the finite element analysis (FEA) that reconstructs the common accident — bus rollover against guardrail on the road side. For the vehicle design, the FEA simulation reveals that strengthening side window pillars is effective, and the side window pillars are therefore improved by selecting proper parameters of material and thickness. The study also shows that the design of guardrail could be improved with an optimal size through uniform design (a methodology of Design of Experiments). The research results not only benefit the design improvement of large passenger vehicles and guardrails, but also provide useful information to the policy makers of safety regulations.
An off-road motorcycle frame has been analyzed and modified to optimize its fatigue life. The fatigue life of the frame is very important to define the service life of the motorcycle.
The strain levels on key parts of the frame were collected during experimental tests. It has been possible to locate the areas where the maximum stress level is reached.
A finite element (FE) model of the frame has been developed and used for estimating its fatigue life. Static test bench results have been used to validate the FE model. The accuracy of the finite element model is good, the errors are always below 5% with respect to measured data.
The mission profile of the motorcycle is dominated by off-road use, with stress levels close to yield point, so a strain-life approach has been applied for estimating the fatigue life of the frame.
Particular attention has been paid to the analysis of the welded connections. A shell and a 3D FE model have been combined to simulate the stress histories at the welds. Two reference maneuvers have been considered as loading conditions. The computed stresses have been used to assess the life of the frame according to the notch stress approach (Radaj & Seeger). The method correlates the stress range in a idealized notch, characterized by a fictitious radius in the weld toe or root, to the fatigue life by using a single S-N curve.
New technical frame layouts have been proposed and verified by means of the developed finite element model.
The considered approach allows to speed up the design process and to reduce the testing phase.
The InTenso+ system has been developed at Politecnico di Milano (Technical University of Milan) for the measurement of the centre of gravity location and of the inertia tensor of vehicles and their components (such as gearboxes and engines). The test rig is basically a multi-bar pendulum carrying the body under investigation and oscillating from well-known initial conditions. By means of a proper mathematical procedure, the mass properties of the body are accurately measured within a very short time.
The InTenso+ System has been employed for a number of measurements of the mass properties of road vehicles. In this paper, the measured data are collected and analyzed.
Formulas for the estimation of the mass properties (mass, centre of gravity location and inertia tensor) from easily accessible vehicle data are proposed and tested against the measured values. It is confirmed that the mass properties coming from the considered estimations are useless if accurate simulations of the dynamic behavior of a vehicle have to be performed.
This work presents an optimal approach to the embodiment stage of the engineering design of a gear train of a hybrid electric off-road vehicle. The powertrain of the given vehicle has a series configuration and is designed for extreme operation conditions, including narrow paths, highly irregular surface roughness and high grade scenarios. The gear train of interest has a predetermined configuration with a fixed total reduction ratio. The gear train is composed by three stages: first, a spur gear pair; in the second stage a bevel gear pair; finally in the third stage a planetary gear transmitting motion to the wheel. In addition to the structural constraints, the design optimization is strongly constrained by space limitations (packaging). The objective function is to minimize the overall mass of the gear train.
Three optimization routines were applied for the solution of this optimization problem: a gradient based optimization (GBA), genetic algorithms (GA) and a branch and bound algorithm for mixed integer problems (B&B). For the initial guess of each routine, a Sobol low discrepancy sequence (LDS) was used. After the formal statement of the optimization problem, a comparison between the performances of the different optimization algorithms is presented. The numerical results are also compared with some analytical results previously obtained.
It was found that the branch and bound algorithm developed was the most effective to find the mixed integer solution. The genetic algorithm was quite inaccurate, due to the binding geometric constraints of the problem.
When designing a vehicle structure, an optimum design is desired because the structure has a significant impact on its performance. The structure impacts other components in the vehicle as well. The designing process usually involves complex iteration. Analyses must be done at the early stage of the vehicle's development (body-in-white) to minimize the amount of parameter changes needed during the late stage of development. Successfully implementing this strategy reduces the time and cost required to develop an effective vehicle structure. A method known as Simple Structural Surfaces can be used to model the vehicle structure as several planar sheets, as well as determine the forces in each sheet. The downside of using this method is that by using it, determining the deflections in the structure is difficult. In order to eliminate this difficulty, the vehicle is modeled as several beam elements instead. In this method, a finite element method is used to numerically solve for the deflections, reaction forces, and internal loading on each element of the structure. This Simple Structural Beam model can be adapted to allow optimization of the static property of the structure bending stiffness. Dynamic properties of the vehicle structure are also examined through vibration analysis, by determining the fundamental natural frequency of the structure. Vibration also has a large impact on the structure's performance. The goal of the research is to obtain a design that will optimize the static and dynamic properties of the vehicle's structure. In the beam elements, the parameters involved are the length, orientation, cross-sectional area, and moment of inertia. The optimizing process is automated and determines the beam dimensions with largest stiffness to weight ratio. The fundamental natural frequency calculated must be distant from the frequency of the engine, as resonance is also a concern for structural performance. Resonance occurs when the natural frequency of the system is equal to the frequency of a connecting component. This increases the amplitude of vibration significantly and is undesirable for any structural design.
This paper presents a new experimental test rig and experimental findings on tire elastomer-surface friction characteristics that are necessary for modeling tire thermodynamic characteristics and then tire characteristics, including the μ-curve in the driving and braking modes of operation.
Unlike common approaches, the paper offers experimental procedures and test results on both steady and non-steady friction process by introducing (i) velocity factor, (ii) normal pressure distribution, and (iii) a temperature factor in the elastomer-surface contact. The group of (i), (ii), and (iii)-listed factors, taken together, represents the key elements by means of which tribological properties of the tire-road interaction, i.e., an elastomer-surface friction pair, impact the μ-curve.
A system was created for sand traction performance testing of tire prototypes for extraterrestrial use by NASA. The system consists of a suspended sand-filled trough that rotates when driven by the prototype. Sensors are used to determine traction slippage of prototypes, providing a quantitative measure of relative prototype performance. This paper describes system improvements to better simulate extraterrestrial environments and more accurately measure prototype performance. A tire prototype hard stop was designed and built to prevent damage associated with the tire assembly resting in the trough. A rock obstacle was created to simulate rough terrain. A sensor system was designed to more accurately determine tire velocity. Various concepts were developed and prototyped to groom the sand during testing. Computational hardware and software upgrades were made to better facilitate the data acquisition processes. An instructional video was created to explain operational procedures. The sensor system will be integrated with the software and a sand grooming concept will be implemented.
The tire is the main interface between the vehicle and road, and all maneuvers controlled by a driver to road vehicle are achieved by the interaction force between tire and road. In modern vehicle design, tire modeling plays an important role in effectively assessing vehicle handling, ride comfort, and road load analysis. The long term goal of this research is to develop a three-dimensional robust tire model that can be used for road load durability simulation. This work is the first step to the long term goal. This paper presents a new simplified in-plane tire model based on a traditional rigid ring tire model. The interaction between the tire and road is assumed to be patch contact. Optimization technique is used to obtain all key tire parameters of the tire model by minimizing the vertical and horizontal contact forces between the model simulation results and road test data when a tire passes a road bump. After the parameters are identified, a full factorial design of experiments with three levels for each of 8 parameters (horizontal spring stiffness and damper coefficient, vertical spring stiffness and damper coefficient, rotational spring stiffness and damper coefficient between the rim and ring, ring radius, ring residual spring stiffness) is conducted for parameter sensitivity analysis. The three levels for each parameter except the ring radius are 50% increase, 50% decrease, and nominal values. Sensitivity analysis has shown that several parameters are critical to the peak value of the vertical and horizontal contact forces. A quarter-car model is then used to assess ride comfort of the vehicle suspension system. The quarter-car model with the proposed tire model can more accurately predict the ride comfort subject to random road inputs than the one with point contact tire model.
The longitudinal slip-ratio is one of several parameters that govern the magnitude of the longitudinal force generated by a tire and probably the most important. As such, the longitudinal slip-ratio of a tire is an essential measurement required in the construction of longitudinal tire models. In laboratory experimental tests the slip-ratio can typically be controlled by controlling the rotational speeds of two motors. However, in in-situ tests, where the slip-ratio needs to be measured, the slip-ratio is estimated from three other measurements namely the wheel speed, vehicle speed and the rolling radius of the tire. While the wheel speed is fairly inexpensive and easy to measure accurately, the accurate measurement of vehicle speed requires an expensive GPS or similar system. The measurement of the rolling radius is often performed statically and assumed constant or can be measured with an expensive laser displacement sensor. Errors in the all of these measurements are compounded when determining the slip-ratio. This paper proposes a method of measuring the longitudinal slip-ratio by performing image correlation techniques on consecutive images of the tire-road interface obtained from a single inexpensive camera. Since the method makes use of one measurement system the probability of inducing errors in the slip-ratio is reduced.
Classically, fatigue analysis such as Miner's Rule is a representation of the "Residual Strength" method; however it is typically applied to relatively brittle materials using the methods of elasticity. We propose a fatigue-based "Residual Strength" method for synthetic rubber materials used in tire production. We model progressive but very slow cumulative damage by using constant strain rate behavior of the neat material, and material subjected to fatigue loading and by assessing the differences in failure stress and strain values as well as resilience and toughness values. Results are planned to be reflected to S-N curves. Our method will serve as an accurate predictive durability tool for tires build using different materials, fillers, reinforcements and different manufacturing methods.
Requirements play a critical role in the design process. Much of the project time is spent eliciting the requirements. However, it is observed that students primarily only consider requirements while evaluating the concepts. This paper presents a case study conducted with senior mechanical engineering design students in a capstone course to begin to understand requirement evolution throughout a project. Data in the form of weekly requirements was collected from four teams working in parallel on the same industry sponsored project. The paper introduces the concepts of completeness and specificity that could allow the use of requirements as a tool for measuring project health. The findings from the case study reveal that the completeness and specificity of requirements increase from initial week to final week.
This paper presents findings from a study of the evolution of requirements in eight parallel student semester long design projects. Weekly requirements documents were collected and analyzed for the number of functional and non-functional requirements defined by each team. Trends were compared with end of project performance success. The findings provide suggestive, not definitive, evidence that (a) a higher number of defined requirements predicted higher project success, (b) early functional requirement definition relates to project success, and (c) it is important to continually evolve the requirements throughout the project. A set of guidelines and recommendations are developed.
Teaching of design and other fundamental topics in engineering is often isolated to dedicated courses. Thus, an opportunity is missed to foster a culture of engineering design and multidisciplinary problem solving throughout the curriculum. Designettes, defined as brief, vignette-like design challenges, exploit opportunities to integrate design learning experiences in class, across courses, across terms, and across disciplines. When courses join together in a designette, a multidisciplinary learning activity occurs, demonstrating how different subjects are integrated and applied to open-ended problems and grand challenges. Designettes help foster a culture of design, and enables the introduction of multidisciplinary design challenges across all core courses in each semester. These challenges combine problem clarification, concept generation and prototyping with subject content from curricula such as biology, thermodynamics, differential equations, and software with controls. This paper investigates the use of single and multidisciplinary designettes at SUTD. From pre- and post-surveys of junior college students, designettes were found to increase students' awareness of applications and learning of content. From 321 third-semester students across six cohorts, designettes were found to increase students' self-perceptions of their ability to solve multidisciplinary problems.
This paper presents the preliminary results of a motivational study of students enrolled in their capstone design course during their senior year in mechanical engineering at the Florida Institute of Technology. Student teams are assigned a project and teams are tasked with completing a design project over a one-year (2 semesters) span. Data is collected during the beginning of the fall semester and during the end of the spring semester. Two methods were used to collect the data of the class. A live interview was conducted for each of the capstone teams. Within this interview, a range of questions are asked to facilitate an understanding of what motivates the student. An adaptation of the Motivated Learning Strategies Questionnaire (MSLQ) survey instrument was also administered to the students to collect quantitative data. The MSLQ framework divides the instruments into two sets of questions to address motivation and learning. Motivation is comprised of three factors: test anxiety, self-efficacy, and intrinsic value. Statistical analysis is performed on the quantitative data to determine significance or correlation between student motivation and performance. Performance is measured through the student's grade (evaluated by instructor) and peer evaluation (evaluated by team). The analysis is performed through segmenting the sample into international versus domestic, and males versus females; to identify any differences in motivation between the groups. Results indicate there are differences between international and domestic students along all motivational factors. Further, differences are identified between males and females for intrinsic anxiety motivational factors.
Innovation is considered a key to competitiveness of the nation. In order to ensure that graduating students are equipped with innovation skills to meet this challenge, we must ensure that engineering curricula are enhancing students' innovation capabilities. In this paper we investigate if the undergraduate engineering curriculum can have a significant positive effect on students' innovation capabilities. In addition, we investigate if individual difference factors, such as engineering design self-efficacy and self-reported GPA, can be correlated with innovation capabilities. To test this, we assessed students' solutions to specific open ended problems for their level of innovation, or more specifically, originality and technical feasibility. The experiments were replicated at two universities and with a variety of cohorts, including freshman students before and after an introductory engineering course and senior mechanical engineering students before and after a capstone course. We found that that students' innovation capabilities were enhanced by the senior-level capstone course at both universities. Similar positive results can be found for the overall four year curriculum at both schools. While individual differences in academic performance and engineering design self-efficacy did not predict seniors' performance, these individual difference factors did interact to influence originality in the freshmen students. At high levels of GPA, increased self-efficacy led to increased originality, but at low levels of GPA, increased self-efficacy led to lower originality scores. Results are discussed in relation to prior research and suggestions are made to track freshmen students to better train future engineers.
The learning process is affected by various elements in the classroom. An enhanced learning experience can maximize students' positive emotional states, and therefore, students' learning achievements. Thus, identifying lectures that provide a superior learning experience is critical to improving students' attention during classroom activities. In this paper, the authors propose a methodology that quantifies students' emotional states in order to identify lectures that provide enhanced learning experiences. An attitudinal survey considering relevant emotional states in a classroom setting such as engagement, delight, interest, boredom, frustration, and confusion was used to evaluate students' emotions and their intensities. Correlation analysis indicated that positive and negative emotions were strongly positively correlated (r > 0.6) and moderately positively correlated (r > 0.4) among them respectively. Confusion was found to be the emotional state with lowest correlation coefficients. On the other hand, engagement and boredom were strongly negatively related with a correlation coefficient of −0.74. Additionally, perceived teaching style was at least moderately correlated to each one of the students' emotional states. Unexpectedly, perceived teaching style was not correlated to perceived difficulty of the lecture (r = −0.01). Finally, the authors demonstrated that the use of Value Path Graph (VPG) is useful to identify lectures that provide an enhanced learning experience on various dimensions.
Synthesis is a common activity in engineering design. It is widely recognized to be important to the whole engineering design process in general, and to the early design stages in particular. In the past, however, there remains lack of a set of rigorous metrics to evaluate the effectiveness of performing design synthesis in conceptual design. Based on relevant studies of abductive reasoning in logic, this paper introduces a set of domain-independent design synthesis metric: clarity, feasibility, testability, simplicity, and analogy. For each metrics, the rationale of including it is explained, and a systemic evaluation procedure is prescribed. Individually, each metrics addresses a particular aspect of design synthesis in conceptual design. Collectively, the combined consideration of all metrics as a single vector helps the designer to identify the most promising synthesis outcome, the best design concept, which both satisfies upstream objectives and meets downstream constraints.
Students, especially from the underrepresented groups, are largely underprepared for and unaware of all the STEM opportunities at the undergraduate level. We have recognized this need with two populations: students that come directly out of K-12 schools and military veterans transitioning into college.
We offer two programs to combat lower STEM enrollment and attrition at post-secondary institutions: a Research Experience for Teachers program that instructs teachers on an innovative product realization process to excite their K-12 students about STEM disciplines and an Experiential Learning for Veterans in Assistive Technology and Engineering program as a mechanism to advise and prepare Veterans with disabilities for their transition from the combat field to an academic career.
In the following paper we look at a novel attempt to combining the two seemingly diverse populations of Teachers and Veterans in a single training initiative, made possible by their overlapping needs and STEM theme.
The purpose of this study is to continue to explore which function identification methods work best for specific design tasks. Prior literature describes the top-down and bottom-up approaches as equivalent methods for functional decomposition. Building on our prior work, this study tests the bottom-up method against the top-down and enumeration methods. We used a 3-factor within-subject study (n=136). While most of our diagram-oriented metrics were not statistically different, we found statistical support that: 1.) students reported that the dissection activity was more useful when using bottom-up, and 2.) that student engineers committed many more syntax errors when using the bottom-up method (by listing parts instead of functions). We believe that both these results are due to the increased focus on individual parts. We do not know if an increased attention to the parts would increase novelty or fixation, and recommend future studies to find out.
Problem formulation is an essential design skill for which assessment methods have been less commonly developed. In order to evaluate the progress of a group of graduate students in mechanical engineering design in regard with the problem formulation skill, they were asked to work on three design problems using the Problem Formulator web tool during their course work. Changes in a set of measures elicited from this data were examined in addition to sketches, simulations, and working prototypes. Inventories of requirements and issues, as well as concepts derived from morphological charts were created to assess designers' skills and outcomes.
We have seen an increase in engineering competitions for high school and collegiate students ranging from concrete canoes [1] to human powered vehicles [2], FIRST Robotics [3] to iGem [4], and hackathons to business plan competitions. Each of these efforts challenges students to develop new ideas, methodologies, technologies, and designs to solve problems. Indeed, on a larger scale, X-Prize competitions foster innovation by getting top inventors to compete against one another to create solution methodologies in specific problem domains (e.g., automotive, space, or genomics).
We have developed the Y-Prize competition that flips the X-Prize structure by challenging students to innovate in the problem space instead of the solution space. In the problem space, students compete to develop the best applications for technological solutions that have been developed in university research laboratories. The three goals of the Y-Prize competition are: a) Expose a wide range of students in and outside engineering to emerging technology and to shine the spotlight on the opportunities in research labs on campus; b) Educate university students on the challenges inherent with technology transfer in research laboratories and engage them in technological innovation; and c) Develop and evaluate a new methodology for innovation based on cutting-edge university research which dramatically increases the number of students engaged in technology transfer.
This paper examines the use of language (text and verbal communication) across school and work settings. The participants of the study are from two distinct pools — 380 first-year engineering students and 355 industry professionals. To test the study predictions and interpret the results the individual data sets from both studies were reviewed and analyzed. Data suggests that for the professional engineering population, face to face communication was the preferred communication mode for sharing engineering evaluation, communicating difficult concepts, and describing their work product. Email and file sharing were also utilized communication options, but to a lesser extent. Data from students facing a simulated professional assignment (produce a fabrication instruction for assembling a mechanical object) indicated that 94% of the students' chose to use language to produce fabrication instructions, compared to only 6% of students who used another tool of engineering representation in the form of sketches. Data investigation and outcomes are discussed in terms of prevalence and importance of language in engineering education.
While much prior work has been done regarding sketching and its impact on design and a few on how to train engineers to sketch, there have been no prior studies in engineering to reduce inhibition to frequent sketching. This paper describes a sketching intervention developed from art teaching aimed at reducing inhibition to sketching and a study to evaluate its effectiveness. In the study, students (n = 55) were tested with pre-mid-post assessments consisting of a mechanical, organic, and design-oriented sketching task and a TLX survey measuring the level of difficulty. The study found that the students overwhelmingly reported their inhibition was lowered, but the short-term TLX data suggested inhibition was higher. However, the TLX data showed a longterm decrease in inhibition-related measures, perhaps suggesting that long-term encouragement to sketch is effective in reducing inhibition to sketch. These results tentatively suggest that sketch inhibition is reduced by actively promoting creativity and sketching, some use of the activities presented here, and by deemphasizing the importance of higher-level skills such as perspective drawing.
Creativity is a valuable skill for today's workplace and one that universities should be emphasizing in the classroom. Teaching creativity usually involves the completion of "creative exercises" that help an individual understand how to think outside the box. Often individuals that are considered creative "practice" creativity on a daily basis, either through their own will or through their occupation, which increases their creative potential. Creativity is shown to be divided into multiple aspects, one of which is divergent thinking. This study examines participants' divergent thinking skills over nine weeks as they perform a simple design task each week. The participants are split into two groups as they perform an alternative uses test on a weekly basis. Each week a new item is presented and the results are collected and entered in a database. The number of entries per card is analyzed to determine if the participants have increased their divergent thinking ability throughout the nine weeks.
In this work, the researchers explore how a professional engineering designer documents thoughts during the design process. This research will increase understanding of design thinking, improve the effectiveness of the design profession, and create tools for design education. Analyzing professional design behavior is traditionally done using timed design activities that are audio and video recorded to collect design data. The methodology used here is to analyze a set of handwritten design journals used for one long-term project. A comprehensive cognitive coding scheme is applied that has been verified by applying it to the data set and refined through iteration. The coding scheme has also been validated by producing comparative results to similar design studies found in the literature such as Atman, Suwa, and Jain. The results found that the professional was very detailed, spent a considerable amount of time on project management and that students are recording in the design journal for different reasons and at different times during the design process than the professional.
Assistive device design was used in a Junior level Machine Design II course to reinforce design concepts while increasing student awareness of the specialized needs of individual product users. Since these projects addressed the needs of specific users and/or a group of specific users, they were externally funded. This provided an incentive for student groups to accomplish the task assigned with a greater level of attention to detail and need to satisfy the design constraints. In all cases, student teams provided a useable, deliverable device to the customer at the end of the semester. A survey of the customers was completed at the end of the semester to determine customer satisfaction with the process. Overall, customers were highly satisfied with the results, although many expressed frustration due to the project timeline being too long.
In all cases, a useable product was delivered at the end of the project. However, improvements were also possible in all cases and further work will be done on the products to better align them with user needs.
Student response to the project was as expected. The students felt this project was a very valuable learning experience and reinforced not only the course material, but also forced them to learn about technologies not discussed in class. However, many commented that the time required to complete the project as well as the traditional course work was far greater than the time required of their peers taking the course with a "paper" project.
The KEEN Winter Interdisciplinary Design Experience (K-WIDE) is an immersive co-curricular program that exposes students to authentic open-ended design inductively. K-WIDE occurs outside of the curriculum and does not bear any credit. Students do not receive any pay for the program, and their only motivation is to learn about design. We believe that our pedagogical approach which immerses students in intensive design, provides opportunities to learn and apply hands-on skills, and encourages critical reflection is effective in leading participants to become global systems thinkers. Students gain important skills in looking at problems from a wide range of perspectives to consider the societal impact of potential solutions while also being conversant in technical engineering to ensure the viability of a concept. In this paper we present the general pedagogical approach and provide some examples of the effect the program is having on students.
Successful collaborative design requires in-depth communication between experts from different disciplines. Many design decisions are made based on a shared mental model and understanding of key features and functions before the first prototype is built. Large-Scale Immersive Computing Environments (LSICEs) provide the opportunity for teams of experts to view and interact with 3D CAD models using natural human motions to explore potential design configurations. This paper presents the results of a class exercise where student design teams used an LSICE to examine their design ideas and make decisions during the design process. The goal of this research is to gain an understanding of (1) whether the decisions made by the students are improved by full-scale visualizations of their designs in LSICEs, (2) how the use of LSICEs affect the communication of students with collaborators and clients, and (3) how the interaction methods provided in LSICEs affect the design process. The results of this research indicate that the use of LSICEs improves communication among design team members.
The purpose of the flipped classroom approach is to enhance the effectiveness of interactions in class. Nevertheless, in practice, simply asking students to watch lecture recordings at home will not automatically lead to more structured interactions in class. To address this challenge, this paper introduces a new method called the pain index survey, which functions to collect, aggregate, and analyze student's early feedback in terms of how painful they feel over each content slide during their before-class learning. The accumulated pain index survey result can facilitate the teaching/learning of design in two ways. First, different students' common feedbacks will enable the instructor to identify those universally perceived learning difficulties and to address them accordingly via guided instructor-student interactions in class. Second, different students' complementary feedbacks will facilitate the instructor to form study groups respectively to promote the peer-to-peer interactions after class. Two case studies are presented to share some of our preliminary lessons and observations.
This paper describes the introduction and impact of using process oriented guided inquiry learning (POGIL) to increase student engagement in a graduate level engineering optimization class. POGIL exercises were introduced into the class as an effort to enhance student engagement and improve retention of knowledge. The effort revealed that although POGIL has been adopted in many contexts (e.g, materials science, chemical engineering, and computer science), characteristics of the student population and the course may play a significant role in the success of a POGIL implementation. The paper describes the POGIL method, how it was adapted for inclusion in an optimization class, and observations on classroom impacts, engagement, and effectiveness.
This paper presents a game that is developed to help the assessment of teaching and learning activities in a mechatronics course. The game is played with a mobile phone and it follows the dynamics of a 'treasure hunt' where participants follow a route and answer a series of questions that are encrypted in 2D barcodes. Participants interact with the game through a website; which allows to record various types of information related to the gameplay. In addition to gamifying the learning experience for students, the game allows the teacher to quantitatively assess the progression of the students and identify the topics that are challenging to comprehend.
The capstone course in aircraft detail design at the Aerospace Engineering department of Embry-Riddle Aeronautical University will be presented. It is structured as a balanced mixture of lectures and a real-world project given by industry with some other activities carefully conceived to address specific deficiencies encountered in traditional engineering education; specifically, the dissociation in the students minds, or even practicing engineers, between abstract or numerical analysis and real-world design. In earlier semesters students tend to be exposed only to "clean" problems, where only one type of loading or deformation is considered or where certain aspects of the problem, such as attachments, are left out. Furthermore, in many cases these disciplines are taught in isolation, detached from their natural context. This results in students lacking a sense of feel and touch for structural analysis, something also observed for other engineering disciplines; capable of manipulating mathematical formulae but without understanding what the numbers they calculate really mean and therefore deprived of confidence about whether their design is sound or not. A special innovative learning experience at the beginning of the term has been implemented to deal with these problems, which consists, in essence, in a condensed version of the semester-long project.
Uncertainty is ubiquitous in engineering, but everything is modeled perfectly in most of engineering courses. It is critical to expose students to the uncertainty reality in engineering design and make them better prepared for facing and handling uncertainty in the real world. In this paper, we discuss the basics of uncertainty and the need of uncertainty education. We then report what we have done in developing uncertainty teaching materials and using them in several engineering design and analysis courses, including Introduction to Design, Dynamics, and Probabilistic Engineering Design, with demonstrative examples. Using good problems are one of the best ways to teach and learn uncertainty, and creating a repository of engineering uncertainty problems is of great value. We also discuss the progress of our effort in the development of the repository.
It has become common knowledge that effective teaching requires more than just the rote dissemination of knowledge. By using active learning, teachers involve the students in the learning process. As the students subjectively handle the class material, their comprehension and retention improves. In the classroom, teachers commonly prompt actively learning through a verbal cue such as, "We are now going to break into groups." This forces the student to switch from a receptive mental state to an active mental state.
We theorize that this verbal, short duration transition from lecture to active learning, especially in large classroom settings, is not sufficient to make this transition quickly and thus limits how active students are in the active learning session. In this paper we present a technique and exploratory study results for cueing active learning through a representative icon in a visual lecture presentation. This cue enables the students to mentally prepare themselves for actively learning during a more passive part of the lecture. The results of our exploratory study demonstrate that the cued active learning did not conclusively correlate with average student performance, but that it did show a decrease in the standard deviation of performance, thereby demonstrating an improvement in the comprehension of the students that were more likely to perform lower than average. The results of this study will be used to conduct a more formal study including direct measurement of lecture participation by students.
Consideration of environmental sustainability is significantly altering the nature of the mechanical design process. This necessitates integration of sustainability related learning content in design engineering curricula. Although various frameworks for teaching sustainable design exist, a survey conducted among practicing student engineers shows the presence of significant knowledge gaps. To this end, we propose a problem-based framework for contextualizing sustainability assessment within design engineering curricula. Our framework makes it possible for embedding sustainability related concepts within traditional engineering courses and promotes discovery learning among students by means of design exploration. We illustrate our approach using a shape synthesis task that integrates environmental assessment into design by constraining the decision space for domain specific variables. Results from a user survey for analyzing the effects of our framework show its ability to promote both awareness and applicability of sustainable design concepts as well as its potential for use in existing engineering curricula.
Doctoral students are required to prepare and defend a research proposal. In this paper, we present five steps for doctoral students to identify the questions that are worthy of investigation and thence to develop a research plan and proposal. Our method involves five steps, namely,
Step 1: Frame the problem
Step 2: Develop a research plan
Step 3: Verification and validation
Step 4: Proposal template
Step 5: Proposal outline
We illustrate the method using the sustainable design of plug-in-electric vehicle charging stations as an example.
Web-based documentation platforms afford lightweight and visually rich mechanisms for designers to share documentation online, yet present challenges regarding representation, particularly for collaborative teams. This paper highlights some of these issues through a descriptive case study based on the use of a new web-based social media tool for documenting the development of design projects called Build in Progress. Undergraduate students worked in teams to design musical construction kits and documented their process using Build in Progress over the course of three weeks. We examined students' project pages to determine trends with how students visually represented their design process, and we gathered students' experiences using the platform through surveys and interviews with select project teams. We found that groups developed their own representations of their design process via tree structures afforded by Build in Progress that present the simultaneous development of distinct elements of their projects and highlight the contributions of each student on the team. The interviews revealed differences between how internal and external documentation are presented and contrasting approaches to creating narrative and instructional documentation based on the intended audience. In particular, we found that students interpreted the tool as one used to help others recreate their design, which led to the omission of several parts of their design process, including experimentation and mistakes. These results suggest the need to further develop tools to support reflection on process rather than product.
The objective of this research is to mine textual data (e.g., online discussion forums) generated by students enrolled in Massive Open Online Courses (MOOCs) in order to quantify students' sentiment, in relation to their course performance. Massive Open Online Courses (MOOCs) are free to anyone with a computing device and a means of connecting to the internet and serve as a new paradigm for distance based education. While student interactions in traditional based brick and mortar classes are readily observable by students and instructors, quantifying the sentiments expressed by students in MOOCs remains challenging. This is in part due to the quantity of textual data being generated by students enrolled in MOOCs, in addition to a lack of quantitative methodologies that discover latent, previously unknown knowledge pertaining to student interactions and sentiments in the digital world.
The authors of this work introduce a data mining driven methodology that employs natural language processing techniques and text mining algorithms to quantify students' sentiments, based on their textual data provided during course assignment discussions. The researchers of this work aim to help educators understand the factors that may impact student performance, team interactions and overall learning outcomes in digital environments such as MOOCs.
In this paper we present a technology assisted flat learning environment, Teaching to Learn (TeatoL), that capitalizes on the research findings on linkages between higher-order thinking and peer-learning. Within TeatoL students are introduced to a "flatter" instructional environment; all participants have dual roles as students and instructors who are embedded in a collaborative environment where all learn collectively from each other's experiences, even the instructor. The main objective of this paper is to understand flat learning environment as a social network. The focus is on peer learning mode, where students are instructors to share their experience and then learn from fellow student instructors. In this paper, we present our initial analysis of a flat learning environment, implemented at the University of Oklahoma, as a network. The participants in the learning environment were given an open design problem related to sheet metal forming. We close the paper with observations from our initial implementations on peer-learning as a network.
Online education is becoming more prevalent in every field, especially with the advent of MOOCs and initiatives such as Coursera, Edx, MITx, Khan Academy and more. Product design education involves open-ended problem solving and prototyping with physical materials, so it presents a number of interesting challenges in an online educational setting.
This paper describes an initial study to better understand the value proposition of offering hands-on product design education using different delivery methods, ranging from hands-on residential to fully online, and combinations in-between. A series of two-day workshops were used to teach students typical introductory product design coursework including opportunity identification and early-stage prototyping. Students attended one workshop session that was taught with one of three content delivery types: traditional (n = 9), online (n = 9), or hybrid (n = 8). Each student worked individually to identify a product opportunity and produce a preliminary prototype. The performance of the students was compared to elucidate any differences based on workshop delivery method.
Based on the comparison of student work, as evaluated by academic product design experts, there were no statistically significant differences in performance between groups. This result suggests that all delivery methods have potential for successfully transferring knowledge to students. Furthermore, this preliminary evidence warrants more detailed investigations of the effects of delivery method on product design education. Interesting observations regarding workshop attendance identify motivation to complete courses as a point of interest in both residential and online settings. A number of insights gained and possible directions are discussed.
Product dissection activities are widely practiced in engineering education as a means of increasing student learning and understanding of core engineering concepts. While recent efforts in this area of research have sought to develop and utilize virtual dissection tools in order to reduce and mitigate the costs of physical dissection activities, little data exists on how virtual dissection impacts student learning and understanding. This lack of data makes it difficult to draw conclusions on the utility of virtual dissection tools for enhancing engineering instruction. In this paper we present the results of a controlled experiment conducted with first-year engineering students developed to examine the impact of virtual dissection on engineering student learning and self-efficacy. Our results revealed that student learning appeared to be unaffected through the use of virtual dissection environments. However, electro-mechanical self-efficacy gains were smaller for students who performed virtual dissection compared to students who performed physical dissection. These results add to our knowledge of the impact that virtual dissection tools can have on student learning and understanding and enable us to develop recommendations and guidelines for improving the effectiveness of these tools in engineering education.
Inquiry of inertial sensory data to monitor and detect seizure sequences in epileptic patients is investigated via experiments and response analysis as well as classification. Experimental motion data incurred from a patient suffering from epileptic seizure as well as a healthy subject employing inertial measurement sensors formed a basis for proposing a suitable detection scheme. The method based on discrete-time Poincare maps in conjunction with third moment has shown promising results. This detection scheme forms the basis of a scheme that can be employed in the classification of activities that encompass an epileptic seizure.
The research objective of this project is to design an ankle stiffness testing and therapeutic device. The hypothesis is that the ankle stiffness of people afflicted with diabetes mellitus (DM) is significantly different from that of healthy subjects. The validation of this hypothesis will allow us to clarify the relationship between ankle stiffness and ulceration or other pathologies. If we can use this objective device to prove that increased stiffness does play a significant role in ulcerations and other pathologies of the foot and ankle, the same device can also be used as a therapeutic device to help reduce ankle stiffness and thus prevent foot ulcers.
Minimally invasive (MIS) total hip arthroplasty is a recently advanced and popularized technique in orthopaedic surgery. The smaller incision site requires the use of small surgical instruments. The purpose of this study was to perform a biomechanical comparison of the cutting efficiency of traditional acetabular reamers and newly designed minimally invasive reamers for use in total hip arthroplasty. Both types of reamers were tested in two different sample materials, Bonesim™ and RenShape®. This study concluded that the new MIS and the traditional acetabular reamers are comparable in their mechanical performances with respect to the force and torque produced while reaming.
The purpose of this study is to manufacture a patient-specific phantom containing multiple aneurysms that can be observed and tested to determine the need for interventional treatment. The vasculatures for the phantoms are taken from unhealthy individuals using rotational angiography as part of a stroke study. Different neurovascular sections exhibiting aneurysms from five patients were combined into a single Circle of Willis with 3D modeling software. Physicians and investigators can use this phantom to test treatment options, such as catheter interventions involving stents and coils.
This work presents the results of a postoperative analysis using X-rays images and shows that results reach the same order of accuracy than with CT image.
Recent research in exoskeletons has examined ways for improving flexibility, wearability as well as reducing weight of overall system. Compliant mechanisms offer a class of articulated multi-body systems that allow relatively stiff but lightweight solution for exoskeleton/brace.
A summary of the manufacturing, in-silico and in-vivo testing of a laser cut cerebral flow-diverting stent (FDS) prototype is presented. The predicted flow-reduction achieved by both variants of the FDS design compares favorably with current commercially available designs. FDS design II is implanted into a swine aneurysm model to validate both the flow-diverting capability and a lack of adverse biological reaction.
Traction therapy is a widely used conservative treatment for low back pain. However, the effects of traction therapy on lumbar spine biomechanics are not well known. We investigated biomechanical effects of two-step traction therapy, which consists of global axial traction and local decompression, on the lumbar spine using a validated three-dimensional finite element model of the lumbar spine. One-third of body weight was applied at the center of the L1 vertebra toward the superior direction for the first axial traction. Anterior translation of L4 spinal bone was considered as the second local decompression. The lordosis angle between the superior planes of the L1 vertebra and sacrum was 44.6° at baseline, 35.2° with global axial traction, and 46.4° with local decompression. The fibers of annulus fibrosus in the posterior region, and intertransverse and posterior longitudinal ligaments experienced stress primarily during global axial traction, these stresses decreased during local decompression. A combination of global axial traction and local decompression would be helpful for reducing tensile stress on the fibers of the annulus fibrosus and ligaments, and intradiscal pressure in traction therapy. The present study could be used to develop a safer and more effective type of traction therapy.
Inspired by advances in robotic hand design, this paper investigates the development of passive, miniature differential mechanisms as implants for attaching muscles and tendons in tendon-transfer surgery. Using cadaver studies, it is shown that the implanted mechanisms lead to better hand function in grasping tasks when compared with current therapies.
Three-dimensional numerical simulations, using the sharp-interface immersed boundary method, are carried out to investigate the effect of aneurysm shape on the hemodynamics of intracranial aneurysm. In our previous work [1] only a single geometry of an aneurysm was tested, but here two three-dimensional geometries are tested by reconstruction from three-dimensional rotational angiography of a human subject [2]. The results support our previous hypothesis [1], i.e., when the vortex formation time scale at the parent artery is smaller than the transportation time scale across the aneurysm neck, the flow aneurysm dome is dominated by a dynamic, unsteady vortex formation.
The aim of this research is to build a patient-specific virtual body shape model for patients of various Body Mass Index (BMI) and body shape. This will enable simulated epidural procedure on patients of various body characteristics, to increase trainee skill, reduce injuries and litigation costs.
Regression analysis (RA) and artificial neural networks (ANN) were implemented to accurately calculate body shape in a data-driven approach. Epidural simulator software was developed containing a screen to enter patient characteristics. When the patient BMI is adjusted, the modelled body shape and tissue layer thickness updates allowing patient specific simulation. The model uses anthropometric measurements as input: body mass, height, age, gender and body shape.
The developed model enables a virtual representation of any actual patient to be built based on their measured parameters for epidural rehearsal prior to in-vivo procedure.
The aim of this research was to create novel computer graphics models of the human spine which can bend, flex and twist. The model aims to realistically duplicate the shape of the spine during various sitting positions adopted by patients during epidural anaesthesia and surgery. The extent of bending and flexing is kept within the limits of spine flexibility. Also the model vertebrate adapt in size and shape to match weight and height of specific patient bodies. The flexible spine model can be of benefit to epidural simulators which require accurate models of spinal vertebrae for needle insertion procedures.
This preliminary study explores material surface chemistry modifications to optimize intramedullary (IM) reaming into femurs. Understanding and quantifying the effects of surface chemistry will allow beneficial new material choices. M2 standard High Speed Steel Straight Shank Straight Fluke chucking reamers of 5/32" or ∼4mm diameter were reamed into RenShape®-BM5460 (bone analogs) blocks for the investigation. Sterilizations (Steam Autoclave and Radio Frequency Glow Discharge Treatment) and low friction coatings (Octadecyltrichlorosilane or ODS and 3-Hepta-fluoropropyl-methyl-dichloro-silane or 3-HEPT) were the surface modifications so far pursued in this study. The effects due to the presence of possible transfer films from bone analogs during reaming on cutting efficacies have been investigated on a custom made Orthopaedic Rotational Cutter Analysis System (ORCAS) test system. The results preliminarily suggest a transfer film from the bone analog resulting in reduction of peak loads and peak toques through repeated use. The low-friction coatings have induced lower peak loads and comparable peak torques, suggesting a corollary between low friction coatings and lower surgical efforts required.
Recent studies show that placement of neurovascular stents during treatment procedure plays a vital role in modifying the hemodynamics in aneurysm sac and parent vessel. This study proposes an improved fast virtual stenting method for stent deployment, which can be used in treatment planning by comparing different treatment strategies. This method is built upon the FVS[1] method by Larrabide et al., which expands the stent within blood vessel by providing artificial mathematical forces. Current method incorporates two innovations: an improved initialization of the stent and an advanced collision detection method between parent vessel and stent to prevent stent from going out of the vessel. These improvements enable this method to deploy stents within time comparable to clinical surgical procedure and help clinicians in quick decision-making during treatment strategy.
Intracranial aneurysms are a potentially devastating pathological dilation of brain arteries that affect 1–5 % of the population. In this study we investigated the vortex structures of both unruptured and ruptured intracranial aneurysms as a discriminating property. We performed pulsatile computational fluid dynamic simulations on 204 patient-specific aneurysm models (57 ruptured and 147 unruptured) derived from patient angiographic imaging. Using Q-criterion we analyzed the coherent structures both throughout the aneurysm volume and at the wall. The relative surface area with positive Q values (indicating vortices at the wall) was able to differentiate ruptured and unruptured aneurysms. For the first time, in a large patient cohort, mechanistic fluid analysis is leading to insights into rupture pathways.
We employed computational fluid dynamics (CFD) and finite element method (FEM) to investigate the hemodynamic effect of two flow-diversion strategies of cerebral aneurysm treatment: overlapping stents and dense compaction of a single stent. Three representative patient-specific aneurysms were used as test cases, and flow diverters were virtually deployed into the models. Aneurysmal hemodynamic modification by flow diverters is strongly correlated with the metal coverage rate across the aneurysm neck, and not uniquely determined by FD deployment strategies. Fusiform aneurysms may be more favorable for achieving dense compaction for increased metal coverage rate than saccuclar aneurysms. To induce high flow reduction, the overlapping strategy may be more suitable for sidewall aneurysms, and the dense compaction strategy for fusiform aneurysms.
A new realistic finite element method (FEM) based endovascular coil deployment technique was developed to explore the hemodynamic modifications of coiling in addition to flow diverter (FD) treatment. A patient-specific internal carotid artery aneurysm was used as a test case, and a single flow diverter was deployed using a previously developed method [1], along with several coils using the new method. Results showed fluctuations in hemodynamic parameters at low packing densities (1–3 coils) which are unexpected. At high packing density however (6 coils), results were consistent with expectations. These results suggest that adding coils at low packing densities to FD treatment may not cause significant additional flow reduction into the aneurysm sac, but may provide a scaffold for aneurysmal thrombus formation.
The American Society of Mechanical Engineers
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