用累积滞后能描述疲劳损伤

A DESCRIPTION OF FATIGUE DAMAGE BY ACCUMULATED HYSTERESIS ENERGY

采用材料在疲劳过程中累积耗散的滞后能来定义疲劳累积损伤,可以克服现有疲劳累积损伤定义的局限,描述疲劳全过程中包括循环硬化(软化)在内的所有损伤变化情况,并能实时测量。建立了仅依赖于常规材料参数的疲劳累积损伤的解析算式和应变疲劳损伤演化方程,并用其对2024-T4铝合金的多级加载应变疲劳寿命进行估算,结果与实验数据符合较好。文中还对现有文献给出的应变疲劳实验数据进行了研究,结果表明,疲劳损伤累积的加载次序效应与材料的循环特性和疲劳寿命均有关。

A new way of defining the fatigue damage variable through the accumulated hysteresis energy of a material in the fatigue process was presented,which could overcome the limitations of the other definitions for the fatigue damage,describe all damage changes including the cyclic hardening (softening)in the fatigue process,and perform the real-time measurement.The calculating approach of the damage variable and the damage evolution e- quation only depended on several conventional material parameters were established.This method was used to the life prediction of strain-controlled step fatigue tests of 2024-T4 aluminum alloy,of which the results were good. By studied the available low-cycle-fatigue experimental data,it has been found that the sequencing effect related to both the cyclic stress-strain behavior and fatigue life of a material.