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层间短纤维强韧化是复合材料层合板层间增韧的有效途径之一。采用三维非线性有限元方法分析了层间短纤维强韧化复合材料层合板的分层扩展问题,探讨其影响因素。以混合模式下通用裂纹扩展的能量准则作为分层扩展判据,通过虚拟裂纹闭合技术计算分层尖端能量释放率。用节点双编号和单元生死技术模拟分层扩展。采用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。采用GAP元处理分层区的接触非线性问题。分析了分层区桥联力对层间应力场、位移场以及分层扩展的影响。研究结果表明,层间短纤维有效延缓了分层扩展,增韧效果明显。
The interlaminar short fiber toughening is one of the effective ways to toughen the interlayer of composite laminates. The three-dimensional nonlinear finite element method was used to analyze the stratified expansion of the laminated short fiber reinforced tough laminates. The influencing factors were also discussed. The energy criterion for universal crack growth in mixed mode was used as the criterion for delamination expansion, and the energy release rate at layered tip was calculated by virtual crack closure technique. Hierarchical Expansion with Node Dual Numbering and Unit Life and Death Techniques. The spring element is used to simulate the action of the interlaminar staple fiber, and the staple fiber bridge force is modified by changing the spring stiffness. Using GAP Element to Deal with Contact Nonlinearity in Layered Area. The effect of bridge-stratification in stratified zone on the stress field, displacement field and stratification is analyzed. The results show that the interlaminar short fibers effectively delay the delamination expansion, and the toughening effect is obvious.