基于随机振动理论的焊接结构疲劳寿命概率预测方法研究

为了能够在设计阶段对承受随机载荷作用的焊接结构的焊缝进行疲劳寿命预测,该文以随机振动理论为基础,结合主S-N曲线法,通过推导证明了用于焊接结构疲劳寿命评估的等效结构应力与激励载荷之间存在线性传递关系,从而提出了一个频域的焊接结构随机振动疲劳寿命概率预测新方法。该方法能够解决多随机载荷作用下复杂焊接结构振动疲劳寿命预测问题。通过T型接头的算例对比分析,证明了该方法能够考虑激励载荷的频率对焊缝疲劳寿命的影响。直接以线路实测随机加速度谱做为激励载荷,对某轨道集装箱平车车体结构关键焊缝的振动疲劳寿命进行预测,结果表明:该方法的预测结果与实际情况吻合,便于工程应用。

RESEARCH ON FATIGUE LIFE PROBABILITY PREDICTION METHOD OF WELDED STRUCTURE BASED ON RANDOM VIBRATION THEORY

For the purpose of making the fatigue life of the weld line in a welded structure under random loads predictable, a series of theoretical deduction is performed to demonstrate the existence of the linear transfer relationship between the load and equivalent structural stress. Then a new fatigue life probability prediction method for welded structures is proposed based on the random vibration theory and the master S-N curve method. The new method can solve the problem of vibration fatigue life prediction for welded structures under multi-random loads. It has the ability to take the effect of load frequency into consideration while calculating the fatigue life of a weld line, which was proved by comparison analysis of T-joint. Actually measured acceleration spectrums on a track were apply in the vibration fatigue life prediction model for a railway container flat car. The calculation results indicate that the predicted results coincide with actual situation. The convenience of the proposed method in engineering application is proved.