搭接长度和铺层方式对CFRP复合材料层合板胶接结构连接性能和损伤行为的影响

Effect of lap length and stacking sequence on strength and damage behaviors of adhesively bonded CFRP composite laminates

针对不同搭接长度和铺层方式的碳纤维增强树脂(CFRP)复合材料层合板单搭胶接结构进行了拉伸试验,观察了试件的受力过程和失效形态,获得了载荷-位移曲线;同时基于连续损伤力学模型和三维Hashin失效准则模拟了CFRP复合材料层合板的层内损伤形成和演化,并利用内聚力模型来模拟层间及胶层的失效损伤,对CFRP复合材料层合板单搭胶接结构在拉伸作用下的失效强度和损伤机制进行了预测,通过对比验证了该数值方法的有效性;通过数值试验比较不同搭接长度和铺层方式的单搭胶接结构及双搭胶接结构的连接强度和损伤行为,并提出了一种优化的CFRP复合材料层合板胶接结构。结果表明:CFRP复合材料层合板胶接结构的极限失效载荷随着搭接长度的增大逐渐增加并趋于稳定值,且结构的失效形式逐渐从胶层自身剪切失效过渡到邻近胶层的层合板层间分层失效;CFRP复合材料层合板胶接结构的连接强度和损伤行为随着铺层方式的不同而改变,通过对3种铺层方式的对比和分析,得到性能最好的铺层方式是[03/903]2S;在搭接长度为5~20mm时,通过对搭接长度进行优化,得到单搭胶接结构的最优搭接长度是17mm,双搭胶接结构的最优搭接长度是19.3mm,与搭接长度为20mm相比,单搭胶接结构和双搭胶接结构的连接强度分别提高了13.26%和0.43%。

The experimental tensile tests have been performed on adhesively bonded single-lap joints of carbon fiber reinforced polymer(CFRP)composite laminates with different lap lengths and stacking sequences.The relevant mechanical responses and damage behaviors were observed during the test process.Finite element(FE)models were built,in which the intralaminar damage was captured using the continuum damage mechanics(CDM)theory derived from 3 D Hashin damage criteria,and the delamination of CFRP composite laminates as well as the failure of adhesive were simulated by cohesive zone model(CZM).The numerical prediction is in a good agreement with the experimental results,which validates the numerical modeling strategy.The effect of lap length and stacking sequence on the bonding strength and damage behaviors was investigated for adhesively bonded joints with single-lap and doublelap configurations.The optimization configuration was obtained using the numerical simulation for adhesively bonded joint of CFRP composite laminates.The results show that the ultimate failure load rises with the increase of the lap length for both single-lap and double-lap configurations,and it finally tends to be a stable value.The failure modes of the joints gradually transform from the shear failure within adhesive film to the delamination within laminates adjacent to the ahesive film.The bonding strength and failure modes also change as the stacking sequence varies,and the optimal stacking sequence is obtained as [03/903]2 sby comparing and analysing three stacking sequences.When the lap length varies in the range of 5-20 mm,the optimum is obtained as 17 mm for single-lap configuration,and that value is 19.3 mm in the double-lap case.Compared with joint with the lap length of 20 mm,the bonding strengths of adhesively bonding single-lap and double-lap joints are increased by 13.26%and 0.43%,respectively.