非耦合韧性断裂准则及其在航空金属材料中的应用

结构轻量化是航空航天和汽车领域的重要发展趋势,对以铝合金、镁合金和钛合金为代表的轻质高强金属材料的需求与日俱增。预测材料的损伤断裂行为是高性能航空构件成形工艺设计和服役性能评估的关键,而发展先进的韧性断裂准则是其主要途径。本文首先介绍了金属材料损伤断裂的微观机制,包括剪切和压缩应力主导的剪切型断裂、拉应力主导的拉伸型断裂及复合型断裂。回顾了韧性断裂准则的研究现状,传统非耦合韧性断裂准则的发展历程、特点和适用场合,重点论述了近年来几种典型的非耦合韧性断裂准则的特点和优势。传统的非耦合韧性断裂准则通常只考虑最大主应力或平均应力对损伤断裂的影响,忽略了偏应力的作用,不适合于低应力三轴度或复杂应力状态下的断裂行为预测;而新的韧性断裂准则综合考虑应力三轴度和罗德角参数对损伤演化的共同影响,适用于复杂的应变路径和应力状态。最后,评述了非耦合韧性断裂准则在铝合金、镁合金和钛合金等航空金属材料中的发展现状和典型应用,展望了韧性断裂准则的发展趋势和研究方向。非耦合韧性断裂准则需针对先进结构金属材料的变形特点,综合考虑应力状态、应变速率、温度及各向异性等对损伤断裂的作用,使其具有更好的普适性和预测精度。

Uncoupled ductile fracture criterion and its applicationin aeronautical metallic materials

Structural lightweight is an important development trend in aerospace and automotive fields,and the demand for lightweight metal materials represented by aluminum alloy,magnesium alloy,and titanium alloy is increasing continuously.Predicting the damage and fracture behavior of advanced metal materials is the key to forming process design and service performance evaluation of high-performance aerospace components,and the development of advanced ductile fracture criteria(DFCs)is the main approach.This paper firstly introduces the microscopic mechanism of ductile fracture of metals,including the shear fracture dominated by shear or compression stress,the tensile fracture dominated by tensile stress,and the mixed fracture.Then,the development history,characteristics,and applications of the traditional uncoupled DFCs are reviewed,and several typical uncoupled ductile fracture models established in recent years as well as their main characteristics and advantages are emphatically discussed.The traditional uncoupled DFCs usually only consider the influence of maximum principal stress or average stress on damage/fracture,and ignore the effect of deviatoric stress,it is not suitable for the prediction of fracture behavior of materials under small stress triaxiality or complex stress state.The recently developed DFCs are more suitable for complex strain path and stress state by considering the joint influence of both stress triaxiality and Lode angle parameter on damage evolution.Whereafter,the development status and typical applications of uncoupled DFCs in aeronautic metals such as aluminum alloy,magnesium alloy,and titanium alloy are reviewed.Finally,this work ends with prospecting the development trend and research direction of DFCs.According to the deformation characteristics of advanced structural metals,new uncoupled DFCs should comprehensively consider the effects of stress state,strain rate,temperature and anisotropy on damage fracture,so as to make it have better applicability and prediction accuracy.