GFRP/铝合金和铝合金/铝合金粘接接头失效对比研究

Comparative Study on the Failure of Adhesively Bonded GFRP/AluminumAlloy and Aluminum Alloy/Aluminum Alloy Joints

为揭示玻璃纤维增强复合材料(GFRP)/铝合金和铝合金/铝合金粘接接头在不同温度和受力形式下的失效规律,加工了处于拉应力、剪应力和拉剪组合应力状态的粘接接头,分别在-40℃(低温)、25℃(常温)和80℃(高温)下进行了测试,结合胶粘剂的玻璃化转变温度(T_g),分析温度和应力状态对接头的失效强度、失效模式和失效准则的影响。结果表明:温度对GFRP/铝合金接头失效强度的影响与应力状态有关,但影响程度低于铝合金/铝合金接头;铝合金/铝合金接头大都是胶层内聚失效,但是GFRP/铝合金接头随着温度的降低和拉应力比例的升高,更容易发生纤维撕裂或分层失效,因而降低失效准则的拟合优度。因此在复合材料粘接结构设计中应尽量降低拉应力的比例,以减小纤维撕裂的倾向,同时在失效预测时须考虑纤维撕裂的影响。

To reveal the failure rules of adhesively bonded glass fiber reinforced polymer(GFRP)/aluminum alloy and aluminum alloy/aluminum alloy joints subjected to different types of loads and temperatures,adhesive joints under tensile,shear,and combined tensile and shear stress states are manufactured,and tested at-40℃(low temperature),25℃(room temperature)and 80℃(high temperature)to analyze the effects of temperature and stress state on the failure strength,failure modes and failure criteria of joints with consideration of the glass transition temperature Tg of the adhesive.The results show that the effect of temperature on the failure strength of GFRP/aluminum alloy joint is related to its stress state,but its extent of influence is lower than that on aluminum alloy/aluminum alloy joint.The most failure mode of aluminum alloy/aluminum alloy joint is cohesive failure in adhesive,while GFRP/aluminum alloy joint is more prone to fiber tear or delamination failure,and hence its goodness of fit of failure criteria drops,with lowering temperature and increasing proportion of tensile stress.Therefore,the proportion of tensile stress should be taken as low as possible in designing the adhesively bonded structure of GFRP for lowering the tendency of fiber tear or delamination,and whose effects have also to be taken into consideration in failure prediction.