一种基于临界平面的多轴载荷循环计数方法

NEW MULTIAXIAL CYCLE COUNTING METHOD BASED ON CRITICAL PLANE

使用临界平面法计算多轴随机载荷作用下的结构寿命时,对平行于临界平面且相互垂直的剪应变历程应当选择合适的循环计数方法。针对该问题,对基于Wang-Brown方法的MWB方法进行了讨论和优化,并提出了一种基于临界面的多轴载荷循环计数方法,以材料变形的记忆性为物理基础划分计数区间,剪应变为主计数参量,正应变为辅助计数参量,逐步将计数区间分解为子计数区间和独立计数区间直至提取出所有载荷循环。对新方法、Wang-Brown方法和MWB方法的计数结果进行对比后认为新方法能够准确的提取多轴载荷历程中的损伤事件,然后将新方法应用于推耙机工作装置疲劳寿命预测中,获得的预测寿命与实际寿命相符。

In critical plane method,a proper cycle counting method should be selected when processing shear components history which perpendicular to each other and parallel to the critical plane such as Case B crack. The MWB method is discussed and optimized firstly and a new multiaxial loading counting method based on critical plane was developed. The new method regarded shear strain as main channel and normal strain as auxiliary channel. According to memory rule for material deformation,counting interval was divided into sub-interval and independent interval step by step. Finally,the new method,Wang-Brown method and MWB method was applied to count a non-proportion multiaxial loading and predict rake dozer H-frame fatigue life respectively,the results show the new method can extract damage event and predict fatigue life accurately.