残余热应力对复合材料双面胶接含裂纹铝合金板修复结构疲劳寿命的影响

摘要

为研究残余热应力对复合材料双面胶接修复损伤金属结构疲劳寿命的影响，利用T300/E51复合材料补片对含中心裂纹的 LY12CZ 铝合金板进行双面胶接修复，研究了修复结构的疲劳寿命，并通过断口分析反推出了疲劳裂纹的扩展情况；利用 Abaqus 软件建立了考虑残余热应力的修复结构的三维有限元模型，分别计算了应力强度因子随裂纹长度的变化关系，并利用二次多项式拟合得到了应力强度因子幅值与裂纹长度的关系式；最后，利用 Pairs 公式材料常数修正法，对修复结构的疲劳寿命进行了预测.结果表明：在相同的疲劳载荷条件下，裂纹板修复结构的疲劳寿命约为未修复裂纹板的23倍；残余热应力会增加裂纹尖端的应力强度因子；有限元模拟的裂纹板修复结构的疲劳寿命与试验结果吻合较好，相对误差为3．7％.%In order to study the effect of thermal residual stress on fatigue life of double-side adhesively bonded composite repairs to damaged metallic plate,LY12CZ aluminum alloy plate containing crack was adhesively bonded with E300/E51 composite patches in two-sides,and the fatigue life of the repaired structure was studied;The crack growth was also investigated from the fracture surface analysis.Simultaneously,the 3-D finite element model with respect of thermal stress effects was built by Abaqus software,and the relations between stress intensity factor (SIF)and crack length were also been calculated by the finite element model.Meanwhile,the relationship between the SIF amplitude and crack length also was got by quadratic polynomials fitting.At last,the materials constant correction method of Pairs law was applied for the fatigue life prediction of the repaired structure.The results indicate that,under the same fatigue load conditions,the fatigue life of cracked plate repaired structure was 23 times as great as unrepaired cracked plate;SIF increased with the increase of thermal residual stress;the fatigue life of cracked plate repaired structure,which was predicted by finite element model,was in good agreement with the experimental result,and the relative error was 3.7%.