冲击载荷作用下层间短纤维增韧研究

Research on the Interlaminar Short Fiber Toughened Composite Panel Under Impact Load

采用基于全量Lagrangian理论的非线性有限元方法研究了冲击载荷作用下含层间短纤维的复合材料层板的分层扩展问题.通过Newmark方法求解动力学方程,以能量释放率作为裂纹扩展准则.用节点双编号和节点分离技术模拟裂纹扩展,用双向弹簧单元模拟层间短纤维作用.通过改变弹簧刚度修正短纤维桥联力,在裂纹表面和冲击接触区设置接触单元,并以罚函数法计算接触力,分析了层间短纤维的桥联作用对裂尖应力场和能量释放率的影响.结果表明:层间短纤维的桥联作用有效地降低了层间应力集中程度和裂尖能量释放率,增韧效果明显.

The delamination crack propagation in composite panels involving interlaminar short fiber under impact load was studied using geometrically non-linear FEM, based on the total Lagrangian formula. The Newmark method was used to solve the dynamics equation. FEM was improved with an effective virtual crack closure technique to evaluate the energy release rate as the criterion for crack propagation. The crack propagation was simulated by node coupling/partition, while the effect of interlaminar short fibers was simulated by the bidirectional spring elements. The bridging strength between short fibers was thus modified by changing the spring stiffness. Contact elements were set up on crack surface and in the area in contact with impact, with the contact force computed through the penalty function algorithm to analyze the bridging effect of interlaminar short fibers on the crack-tip stress field and energy release rate. The results showed that the bridging effect of interlaminar short fibers can effectively reduce the stress concentration and crack-tip energy release rate, thus toughening significantly the short fibers.