增韧复合材料的G_Ⅰ断裂韧性有限元模拟

FINITE ELEMENT SIMULATION OF G_ⅠFRACTURE TOUGHNESS OF TOUGHENED COMPOSITES

采用Abaqus有限元仿真软件建立二维壳单元模型以及内聚力模型,运用双线性本构模型以及二次名义应力准则,对以聚酰亚胺为增韧层的复合材料进行GⅠ断裂韧性模拟,同时通过改变法相刚度、能量释放率等参数探讨对复合材料性质的影响。结果表明,模拟结果与实际情况在曲线趋势上大体一致,随着能量释放率的增大,层间韧性也随之增大,主要是纤维的抽拔、断裂等塑性屈曲对能量的吸收所致。而法相刚度对于层间失效后的脆性断裂影响显著,较大的法相刚度会导致载荷-位移曲线上下波动较大,呈现出层间脆性特性。

The two-dimensional shell element model and cohesive force model were established by using abqaus finite element simulation software and the brittle constitutive model. Besides,the second nominal stress criterion were also used to simulate the fracture toughness of GⅠfracture with polyimide as the toughening layer. The influences of the normal phase stiffness,energy release rate and other parameters on the properties of the composites were discussed. The above experimental results,indicate that the simulation results are consistent with the actual situation in the curve trend. With the increase of the energy release rate,the interlaminar toughness increases with the increase of the energy release rate,which is mainly caused by the absorption of energy by plastic buckling such as pumping and breaking of fibers. In addition,the normal phase stiffness has a significant effect on the brittle fracture after interlaminar failure. Larger normal phase stiffness leads to the fluctuation of the load-displacement curve,which shows the interlaminar brittleness.