张力场对复合材料层板组合梁连接强度的影响

基于纯剪切方板后屈曲阶段边界受力分析,设计了考虑蒙皮支持刚度的复合材料"工"形层板组合梁试验件,采用对角拉伸加载方式,考察了腹板后屈曲张力场对层板组合梁连接强度的影响,并采用基于黏聚区模型的有限元方法对试验进行了仿真分析,研究了界面的失效过程与机理。研究表明:腹板后屈曲阶段形成的张力场在连接界面上产生附加的剥离载荷,使界面呈现Ⅰ/Ⅱ型复合受力状态,加速界面破坏;考虑蒙皮支持刚度的剪切试验在腹板发生失稳后使蒙皮产生法向变形,一定程度上减弱了界面剥离载荷的增加,梁结构的破坏载荷略有提高;试验的破坏模式表现为腹板的纤维压缩破坏和缘条-蒙皮界面的Ⅰ/Ⅱ型复合断裂;黏聚区模型能够很好地模拟复合材料界面的破坏,仿真与试验基本一致。

Effect of tension field on joint strength of CFRP beam

Based on the analysis of boundary force of the pure-shear square plate in the post-buckling stage,the "I-shaped" composite beam test pieces considering the influence of the stiffness of skin supporting are designed to inspect the effect of post-buckling tension field on joint strength of composite beam by diagonal tensile test, and the finite element model based on cohesive zone model is used to simulate the experiment and study the interface failure process and mechanism. The results show that the delamination field generated in the post-buckling stage of the web significantly increases the delamination load at the interface, which leads to I/II complex stress state and accelerates the interface failure. The shearing test which considering the skin supported stiffness makes the skin form normal deformation after instability in the web, to some extent weakens the increase of the interface delamination load, so that the failure load of the beam slightly increases.The final failure mode is the failure of the web fiber compression and I/II complex fracture of the interface.The cohesive zone model can well simulate the fracture of the interface of the composite. And the simulation is basically consistent with the experiment.