点焊结构在随机振动环境下的疲劳寿命研究

摘要

Based on the Dirlik method for vibration fatigue life study in the frequency domain,the finite element model is established and modified according to the model test,and the finite element method is used to predict the fatigue life of the spot welded structure.The effects of different PSD spectral types on the fatigue life under the random vibration environment are analyzed.The analysis results show that with increasing PSD amplitude under the same vibration level in the first natural frequency domain,the fatigue life under random vibration decreases.Under the influence of white noise acceleration power spectrum and when the PSD amplitude was kept unchanged;with increasing bandwidth,the fatigue life under the random vibration environment decreases.The influence of random vibration on the fatigue life in the region of non-resonance frequency between the first and second modal frequencies should not be neglected.%在叙述振动疲劳寿命频域法中的Dirlik方法的基础上,根据模态试验修正有限元模型,采用有限元方法对点焊结构进行随机振动疲劳寿命预测.分析了不同PSD谱型对随机振动疲劳寿命的影响.结果表明:同一振动量级下,处于第1阶固有频率段的PSD幅值增加,随机振动疲劳寿命呈现明显下降趋势;在白噪声加速度功率谱作用下,功率谱密度幅值保持不变的条件下,随着带宽的增加,随机振动寿命呈现减小趋势,第1阶模态频率与第2阶模态频率间的非共振区频率段对随机振动疲劳寿命的影响是不可忽略.