交变载荷对CFRP复合材料-铝合金粘接接头剩余强度的影响

为了给碳纤维增强聚合物（CFRP）复合材料粘接结构的安全设计及应用提供参考，针对CFRP复合材料-铝合金对接接头，研究了拉-拉交变载荷作用下的疲劳寿命特性及剩余强度变化规律。设计专用夹具，完成接头的制作及固化，并测试其拉伸、剪切准静态失效强度，在此基础上进行不同载荷水平下的疲劳寿命测试。选取特定载荷水平，测试不同循环次数后的接头剩余强度，并对失效形式进行观察分析。结果表明:CFRP复合材料-铝合金对接接头强度-寿命（S-N）曲线在单对数坐标上符合线性函数规律；随着交变载荷循环周期的增加，接头剩余强度呈先慢后快的下降趋势，而且在较大的载荷水平下，下降幅度更为明显；经历交变载荷循环前、后接头失效形式发生改变，由局部CFRP复合材料表层撕裂转变为局部界面破坏。结合试验测试所获得的初始失效准则，并引入疲劳退化因子，建立内聚力模型对交变载荷作用下的粘接接头强度衰减进行数值模拟，结果表明所建立模型能够有效预测交变载荷作用下的接头剩余强度。 

Effect of alternating load on residual strength of adhesively bonded CFRP composite-aluminum alloy joints

To provide a reference for the safety design and application of carbon fiber reinforced polymer (CFRP) composites adhesive structure, the fatigue life characteristics and residual strength of adhesively bonded CFRP composite-aluminum alloy butt joint were studied. The special fixture was designed to complete the production and solidification of the joints, and the tensile and shear quasi-static failure strength were tested. On the basis, the fatigue life under different stress levels was tested. The residual strength of the joint under specific load levels after different cycles was obtained and the failure modes are observed and analyzed. The results show that the fatigue stress-number of cycle (S-N) curve of adhesive joints accords with linear function on the single logarithmic coordinate. With the increase of alternating load cycles, the residual strength of the joint decreases, first slowly and then quickly. The decrease is more obvious under the larger load level. The failure modes of joint also changed which from slight fiber tear of CFRP composite transformer into local interfacial failure. Combined with the initial failure criterion obtained by experiment and the fatigue degradation factor, the cohesive zone model is used to simulate the strength attenuation of the adhesive joint under alternating load, and the results show that the model can predict the residual strength of the joint under alternating load effectively.