CFRP复合材料构件胶接特性及失效规律研究

Research on the bonding characteristics and failure rules of CFRP composite

对不同铺层方式和不同胶层厚度的复合材料胶接单搭结构(SLJs)的连接性能进行了研究。使用内聚力模型模拟了SLJs的胶层退化及失效过程,通过与实验对比验证了数值模型的有效性;基于改进后的三维Hashin失效准则,模拟了复合材料层合板的损伤演化。结果表明:胶层的退化形态及失效规律与胶层粘连的复合材料铺层角度密切相关,当胶层两侧粘连的复合材料铺层角度为0°时,胶层会退化形成椭圆环状;当胶层两侧粘连的复合材料铺层角度为45°或-45°时,胶层会退化形成上下中心对称的水滴状;当胶层两侧粘连的复合材料铺层角度为90°时,胶层会退化成沙漏状。0°铺层与胶层相邻时,结构的极限失效载荷最大,此时复合材料未出现损伤;当90°铺层与胶层相邻,结构的极限失效载荷最小且复合材料出现基体损伤、纤维损伤和分层损伤。胶层厚度在0.05~0.5mm时,复合材料胶接单搭结构的连接性能最好,当胶层厚度大于0.5mm,结构的连接性能会大幅下降。

The connection performance of the adhesively bonded single-lap joints(SLJs)of composite with different stacking sequences and different adhesive layer thicknesses was studied.The cohesive zone model(CZM)was used to simulate the damage initiation and failure process of the adhesive layer between the adherends.The effectiveness of the finite element method(FEM)was verified by comparison with the experiment.Based on the improved 3D Hashin failure criterion,the damage evolution of the composite materials was researched.The results show that the damage modes and failure laws of the adhesive layer are related to the angle of the composite material layup.When the angle of the composite material adhesion on both sides of the adhesive layer is 0°,the adhesive layer will degenerate and form an elliptical ring.When the angle is 45°or-45°,the adhesive layer will degenerate and form two droplets symmetrical in the upper and lower centers.When the angle is 90°,the adhesive layer will degenerate and form an hourglass shape.When the 0°layup is adjacent to the adhesive layer,the structure has the largest ultimate failure load and no damage appears in the composite materials.When the 90°layup is adjacent to the adhesive layer,the structure has the lowest ultimate failure load,and the composite material will have matrix damage,fiber damage and delamination.With the thickness of the adhesive layer between 0.05 mm and 0.5 mm,the adhesively bonded single-lap joints have better connection performance.If the thickness of the adhesive layer is greater than 0.5mm,the connection performance of the SLJs will be greatly reduced.