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Dynamic reliability based design optimization of the lifting gear transmission system for mining excavator

In this paper, a dynamic reliability based design optimization problem of the lifting gear transmission system is formulated and solved. We focus on two issues in the design process, one is the excitations of the lifting gear transmission system, the random speed input, time variant meshing stiffness, dynamic loads are analyzed. The other is two kinds of reliability constraints, time-invariant reliability constraints for bending stress, and dynamic reliability constraints for contact strength life. Considering the two issues, a reliability based multi-objective design optimization problem is formulated. In this optimization problem, the distance between natural frequency and meshing frequency is maximized, the volume of gears is minimized, and the dynamic reliability constraints are simplified by considering the worst case. The design optimization results considering the two issues are compared with the initial design, which demonstrate the performance improvement of the optimized design points. In the further study, three issues should be studied. One is the correlation between failure models, and the autocorrelation in each failure process, which should be considered to obtain more accurate results. The second is to analyze the influence of transmission error to vibration. The third is to analyze the dynamic performance of bearings, shafts, and gear box.