AA7075-T6复杂加载状态下断裂极限研究  

Study on fracture limit of AA7075-T6 under complex loading state

作　　者：江娜 尚宏春 王计真 李旭阳 张冲[1] 王松臣 娄燕山 JIANG Na;SHANG Hongchun;WANG Jizhen;LI Xuyang;ZHANG Chong;WANG Songchen;LOU Yanshan(School of Mechanical Engineering,Xi'an Jiaotong University,710049 Xi'an,China;China Aircraft Strength Institute,710065 Xi'an,China)

机构地区：[1]西安交通大学机械工程学院,西安710049 [2]中国飞机强度研究所,西安710065

出　　处：《应用力学学报》2022年第4期617-626,共10页Chinese Journal of Applied Mechanics

基　　金：国家自然科学基金资助项目(No.52075423)。

摘　　要：为研究航空铝合金AA7075-T6板材在复杂加载状态下的韧性断裂力学性能,设计4种包含不同应力状态的拉伸试验和液压胀形试验来获取材料的硬化特性和断裂参数。通过不同应变率和不同轧制方向的拉伸试验得到相应的应力-应变曲线,分别采用不同硬化模型和DF2016韧性断裂准则对其硬化行为和断裂特性进行表征。结果表明AA7075-T6狗棒试件在应变率为1 s^(-1)和10 s^(-1)时重复性较好,应变率为100 s^(-1)时应力-应变曲线出现明显的抖动,但随着应变率的增加没有出现明显的应变率强化效应。而且对比7个轧制方向的应力-应变结果发现,不同角度的拉伸强度和断裂应变基本相同。因此在研究范围内AA7075-T6表现为一种各向同性且关于应变率不敏感的材料。采用Swift-Voce硬化模型的预测效果最好,DF2016韧性断裂准则可以准确预测AA7075-T6在剪切、单轴拉伸、平面应变拉伸和等轴拉伸等不同应力状态的断裂位置。In order to study the ductile fracture mechanical properties of aviation aluminum alloy AA7075-T6 sheet under complex loading states, four tensile tests and hydraulic bulging tests with different stress states were designed to obtain the hardening properties and fracture parameters of the material.Corresponding stress-strain curves were obtained through tensile tests at different strain rates and rolling directions, and different hardening models and DF2016 ductile fracture criterion were used to characterize their hardening behavior and fracture properties.The results show that the AA7075-T6 dogbone specimen has good repeatability when the strain rate is 1 s^(-1) and 10 s^(-1),and the stress-strain curve shows obvious jitter when the strain rate is 100 s^(-1),but it does not increase with the increase of the strain rate.A significant strain rate strengthening effect appears.Moreover, comparison of the stress-strain results in the seven rolling directions reveals that the tensile strength and fracture strain of different angles are basically the same.Therefore AA7075-T6 behaves as an isotropic and insensitive material with respect to strain rate in the study range.The Swift-Voce hardening model is used to predict the best results, and the DF2016 ductile fracture criterion can accurately predict the fracture position of AA7075-T6 in different stress states such as shear, uniaxial tension, plane strain tension and equiaxed tension.

关 键 词：断裂参数 7075铝合金 应变率 力学性能 试验 

分 类 号：TH142.2[一般工业技术—材料科学与工程]