腐蚀疲劳交替下2A12-T4航空铝合金的寿命分析研究

Life Analysis of 2A12-T4 Aeronautical Aluminum Alloy Under Alternating Mode of Corrosion Fatigue with Load Interaction

基于飞机服役期间经历“地面腐蚀与空中疲劳”的交替损伤模式,考虑载荷间的相互作用,研究了航空铝合金2A12-T4在预腐蚀与“腐蚀+疲劳”交替模式下疲劳寿命的退化与损伤累积规律。同级加载条件下提出利用腐蚀疲劳耦合损伤指数和迟滞载荷用来描述考虑交替腐蚀疲劳损伤模式,用各级疲劳损伤间的相互影响及腐蚀损伤与疲劳损伤在服役工作期间的耦合作用来描述腐蚀、疲劳间的相互促进、加速劣化的现象。基于损伤力学和非线性累积理论,考虑载腐蚀疲劳耦合指数与迟滞载荷对传统的Miner线性累积损伤理论进行修正。建立了飞机结构材料的寿命计算模型,并将模型计算结果与试验结果进行对比验证。确定了腐蚀实验中的腐蚀耦合损伤,并利用低载锻炼效应理论得出均匀分布的迟滞载荷。计算结果表明,本文提出的寿命计算模型的结果与实验结果比较吻合。

Based on the alternate mode of"ground corrosion and air fatigue"damage during aircraft service,this paper consid-ers the interaction between loads to study the fatigue life degradation and damage accumulation of aviation aluminum alloy 2A12-T4 under alternate modes of pre-corrosion and"corrosion+fatigue"law.Under the same level of loading conditions,it is proposed to use the corrosion fatigue coupling damage index and the hysteresis load to describe the alternate corrosion fatigue damage mode.The interaction between the fatigue damage at various levels and the coupling effect of corrosion damage and fa-tigue damage during service work are used to describe the mutual promotion and accelerated deterioration of corrosion and fa-tigue.Based on damage mechanics and non-linear accumulation theory,the traditional Miner linear accumulation damage theory is modified by considering the corrosion fatigue coupling index and hysteresis load.The life calculation model of aircraft structural materials is established,and the calculation results of the model are compared with the test results.The corrosion cou-pling damage is determined in the corrosion experiment,and a uniformly distributed hysteretic load is obtained by using the theory of low-load exercise effect.The calculation results show that the results of the life calculation model proposed in this paper are more consistent with the test results.