铝合金薄板冲击后疲劳试验与谱载寿命  

Fatigue experiments and lifetime for post-impact sheets of aluminum-alloys(AAs)under block spectrum loading

作　　者：张亦波[1] 陈迪 成正强 沈培良[1] 熊峻江[2] ZHANG Yibo;CHEN Di;CHENG Zhengqiang;SHEN Peiliang;XIONG Junjiang(Airframe Integration Department,Shanghai Aircraft Design and Research Institute,Shanghai 201210,China;School of Transportation Science and Engineering,Beihang University,Beijing 100083,China)

机构地区：[1]上海飞机设计研究院机体集成部,上海201210 [2]北京航空航天大学交通科学与工程学院,北京100083

出　　处：《航空学报》2022年第1期373-386,共14页Acta Aeronautica et Astronautica Sinica

基　　金：国家自然科学基金(51875021)。

摘　　要：对航空铝合金2524-T3和7075-T62薄板分别进行了4种不同冲击能量的低速冲击试验,并对冲击后薄板进行了静力拉伸、恒幅加载疲劳性能及块谱加载疲劳寿命试验,研究了冲击凹坑尺寸(或冲击能量)对静力性能、疲劳强度以及疲劳寿命的影响;根据断口形貌和试验观察,分析和讨论了冲击对疲劳特性和损伤机理的影响。为估算冲击后薄板谱载疲劳寿命,在试验基础上提出新的冲击后薄板疲劳性能S-N-Kt表征模型,采用新模型处理试验数据,得到的理论结果与试验数据吻合良好。基于Johnson-Cook本构方程,建立了冲击后铝合金薄板的非线性弹塑性有限元模型,模拟了冲击凹坑附近的残余应力和应力集中;利用冲击后薄板疲劳性能S-N-Kt模型,预测了冲击后的航空铝合金2524-T3和7075-T62薄板的块谱疲劳寿命,预测结果和试验数据吻合良好,精度可接受。Tests of low velocity impact are performed on the sheets of AAs 2524-T3 and 7075-T62,respectively,with four different impact forces,and static and fatigue experiments are conducted on the intact and post-impact sheets under static tensile,constant amplitude and block spectrum loading.The impact-dent size,static and fatigue properties,and spectrum-loading life are determined,with the effect of impact on fatigue characteristics and damage mechanism analyzed and discussed from fractographic and experimental observations.An S-N-Kt surface model is proposed to depict fatigue characteristics for fatigue lifetime prediction of post-impact sheets subjected to block spectrum loading.A new concept is applied for experimental data and a reasonable agreement obtained between the theoretical and experimental results,demonstrating the effective and practical use of the developed surface model.A nonlinear elastic-plastic FE model based on the Johnson-Cook constitutive equation is generated to model the residual stress patterns and stress concentration around the impact-dent,and fatigue lives of post-impact sheets of AAs 2524-T3 and 7075-T62 subjected to block spectrum loading are predicted from the S-N-Kt surface model.Good agreements have been achieved between predictions and experiments.

关 键 词：疲劳 低速冲击 铝合金薄板 寿命 块谱加载 

分 类 号：V216.3[航空宇航科学与技术—航空宇航推进理论与工程]