基于一种新临界面的多轴载荷疲劳寿命预测方法

FATIGUE LIFE PREDICTION BASED ON NEW CRITICAL PLANE FOR IRREGULAR MULTI-AXIAL LOADING

考虑多轴载荷下路径变化的不确定性,引入权函数的概念,得到一个新的临界面的确定方法。采用雨流计数方法,结合能体现载荷间相互影响的Morrow的非线性损伤律,应用FS(Fatemi Socie)模型对304不锈钢进行非规则载荷下低周疲劳寿命预测。同时采用最大损伤面方法结合FS模型进行寿命预测,结果表明,对该模型而言,结合考虑权函数的影响后得到新的临界面,最大损伤面方法与最大剪应变方法都给出较好的结果。

A new critical plane approach called the weight function-critical plane is proposed to consider the uncertainty of the irregular path under the multi-axial loading. Rainflow cycle counting and Morrow＇ s plastic work interaction rule are used to calculate fa- tigue damage. Low-cycle fatigue data of type 304 stainless steel obtained under axial-torsional loading are analyzed using FS model based on the new weight function critical plane. The fatigue life prediction is also conducted by using the maximum darnage plane as the critical plane for FS（Fatemi Soeie） model. It is concluded that the results gained by the maximum damage plane as the critical plane and the maximum shear strain plane as the critical plane by considering the weight function are both acceptable for the case examined.