基于多元可靠性模型的复杂结构件危险点选取方法

Weak Point Selection Method for Complex Structures with Multi-Variable Reliability Model

为了准确评估复杂结构件的疲劳寿命及可靠性,提出了基于多元可靠性模型的复杂结构件危险点选取方法。该方法综合考虑了载荷不确定性、材料性能不确定性、载荷作用次数以及材料强度退化对危险点疲劳寿命及可靠性的影响,同时也为其他机械结构件危险点的选取提供了规范的判定依据。以某型号地铁列车枕梁为例,详细展示了利用多元可靠性模型选取枕梁结构件危险点的具体计算过程,并对枕梁的疲劳可靠性进行了评估。结果表明:在以应力集中为依据确定的28个枕梁结构件潜在危险点中,只有2个是对枕梁疲劳可靠性构成影响的真正危险点,同时,该列车枕梁在设计的服役环境下完全满足安全服役30a的设计要求,并且服役60a的累计失效概率仅为0.75%。

To accurately evaluate the fatigue life and reliability of complex structures, a weak point selection method for complex structures with multi variable reliability model is proposed. The impact of load uncertainty, material properties uncertainty, number of load application, and material strength degradation for the fatigue life and reliability are taken into account, and a standard for other mechanical structures to determine their weak points is provided. A metro train bolster is taken as an example to show the specific calculation process of selecting weak points by the multi variable reliability model in detail and the fatigue reliability is evaluated. The results indicate that only two weak points among 28 potential weak points determined by stress concentration criterion are the real ones affecting the fatigue reliability of the bolster, the bolster meets the 30 year design requirement for safe service, and its cumulative failure probability is only 0. 75% within the 60 year service.