复 杂 冲 击 载 荷 下 螺 栓 松 动 失 效 边 界 分 析

Here, to identify loosening failure boundary of bolted joint structures under complex impact load, a boundary determination method based on evolutionary power spectral density was proposed. Firstly, impact tests were conducted for typical bolted joint structures under complex impact load to record structural strain responses under different tightening torque conditions. Based on wavelet transform, the evolution power spectral density matrix of impact responses was derived, and curves of strain root mean square values at monitoring points versus variation of tightening torque were calculated accordingly to reveal evolution law of bolt loosening failure. Subsequently, a refined finite element model of a bolted joint structure was established, and the correctness of the model was verified by comparing its strain simulation results in time-domain and frequency-domain with those obtained in tests. Then, effects of impact load parameters on loosening failure boundary were analyzed using this finite element model. The results showed that with increase in inflection point frequency of shock response spectrum, loosening failure boundary of bolted joint structure exhibits an upward trend; under impact action of lower inflection point frequency, bolted joint structure is more prone to loosening and failure.