冲击作用下复合材料叠层板层间开裂演化模型

AN EVOLUTION MODEL OF DELAMINATION FOR COMPOSITE LAMINATES UNDER EXTERNAL IMPACT

采用双线性特性破坏模型研究了复合材料叠层板层间开裂裂纹的演化,通过引入弹性/剪切模量的损伤参数,推导出损伤参数与应变之间的微分方程,并得到裂纹耗散功率与损伤参数变化率之间的关系.计算不同初始冲击速度下复合材料叠层板某界面上应变、应变率响应以及损伤参数的演化,即可得到该界面发生层间开裂的情形及其对剪切模量的影响.通过检查界面各点处的损伤参数是否发生改变,预测了冲击完成之后复合材料叠层板第1,2层之间发生层间开裂区域的大小与位置;该预测结果与实验数据及其他破坏准则计算结果基本相符.计算结果表明,在冲击过程中当界面上任意点处的剪应力超过剪切强度后,该点附近的剪切模量开始发生衰减,衰减大小随铁球初始冲击速度的增大而增大,并从靠近冲击中心的位置逐渐向周围递减.在四边简支边界条件下,复合材料叠层板的层间开裂区域同样最先出现在界面中靠近冲击点的位置,区域面积随初始冲击速度的增大不断扩大.当初始冲击速度足够高时,第1,2层界面的两条对称轴上开始出现多个独立的开裂区域.

As a result of The evolution of delamination is studied by using double-linear characteristic model of damage.With a representation of damage parameters for elastic/shear moduli,a series of differential equations of damage parameters with respect to strain are derived,and the relations of cracking dissipated work with respect to damage parameters are also obtained.By computing the evolution of strain,strain rate and damage parameters in a certain interface of composite laminates under impact with variety of initial velocities, delamination in the interface and its effect to shear moduli are yielded.Then the delamination regions between the first and the second layer after impact are evaluated by checking whether one of damage parameters is changed at each point in interface.The result shows that the shear moduli start to decay in the point where shear stress reaches the shear strength.The decaying amplitude increases as the initial impact velocity of iron ball being raised,while it decreases outwards from the impact point nearby.With all boundaries simply supported,the delamination region appears firstly in the center of one interface,and they expand as the initial impact velocity being raised.Several independent delamination regions will appear along two symmetric axes of interface plane between the first and the second layer of composite laminates if the initial impact velocity is higher enough.