{'fraction_non_alphanumeric': 0.01582471089470481, 'fraction_numerical': 0.0, 'mean_word_length': 5.2988505747126435, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Dynamic response control of centrifugal pendulum vibration absorber with motion-limiting device during startup in gravity field

The dynamic performance of a vertically rotating centrifugal pendulum vibration absorber (CPVA) during engine start-up was investigated. The equations of motion were established using a Lagrange equation of the second kind containing terms for gravity and the motion-limiting device of the absorber, respectively. The optimal positioning of the motion-limiting device was determined from the perspective of CPVA stability and damping capability, and the terminology for the CPVA damping quality factor was defined to evaluate the damping capability of the absorber. Simulink models were established to simulate the behaviour of the absorbers at different speeds during engine initiation and assess the impact between the absorber and motion-limiting device during engine start. Based on the results, the concept of knocking power was proposed, and it was shown that resonance occurring during engine start worsens the noise, vibration and harshness (NVH) performance of the system. It was further shown that the initial position of the absorber at the moment of engine start to turn affects the knocking power and, as a result, the startup noise of the CPVA. The study also finds that the transient position of the absorber at the engine ignition time affects the knocking power. The responses of CPVA under different working conditions were tested on an electric bench and compared with simulation results. Based on our results, we propose several measures to control absorber behaviour and reduce knocking power.