复合材料低速冲击损伤研究及等效模型的应用

复合材料低速冲击损伤的特殊性及危害性使得对航空复合材料冲击损伤的评估尤为重要。该文通过建立数值计算模型并结合实验数据解决了4个方面的应用问题:1)在ABAQUS子程序VUMAT中引入损伤模式及损伤演化,结合层间连接单元对层合板低速冲击损伤进行了模拟;2)损伤容限设计方法要求对含缺陷结构的极限强度做出正确的评估,通过ABAQUS子程序USDFLD引入损伤模式及材料折减方案,得到了含圆孔的层合板极限拉压强度;3)通过ABAQUS子程序UMAT引入损伤模式及刚度折减方案,结合层间连接单元,模拟了含预制分层的层合板压缩失效问题;4)针对共用铺层结构的工程有限元计算问题,提出了力学等效模型,将该模型应用到结构级的静力实验模拟并拓展至结构冲击模拟。

DAMAGE OF COMPOSITE UNDER LOW-VELOCITY IMPACT AND APPLICATION OF MECHANICAL EQUIVALENT MODEL

The particularity and harmfulness of composite material damage caused by low-velocity impact makes it very important to assess the damage of aerospace structures.Through developed numerical model and experiment data,four aspects of application problems are solved in this paper: 1) By means of ABAQUS user subroutine VUMAT,which includes damage criterion and evolution,and by combining with a cohesive model,the damage of a laminate under low-velocity is simulated;2) Damage tolerance design method requests the correct estimate of structures consisting of defects.By means of ABAQUS user subroutine USDFLD,which introduces damage criterion and material reduction,the ultimate strength of composite laminates including a circular hole under tension and compression loading is carried out;3) Delamination has important influence on the compression of a composite laminate.By means of ABAQUS user subroutine UMAT combined with a cohesive model,which introduces damage criterion and stiffness reduction,the failure of the composite laminate as well as the prefabricated delamination under compression are simulated;4) A mechanical equivalent model is proposed to solve the practical simulation of a co-curing structure.The model developed in this paper has obtained a good agreement with static structural experiment data and also been extended to the dynamic impact simulation.