三维整体编织复合材料低速冲击失效多尺度分析

Three-dimensional (3-D) composites were used wider and wider. But the 3-D braided composites usually subject to low-velocity impact which will course damage of structure and decrease of load capacity, during the processing of manufacture, using, and maintenance. This project focuses on the low-velocity impact responses of 3-D braided composites with experimental and finite element methods. The multi-scale microstructure models from yarns, unit cell of 3-D braided fabric, full size 3-D braided fabric and their composites are built. A user defined materials subroutine which contains the constitutive relationship and failure criterion is compiled. The low-velocity impact response characters of 3-D braided composites are calculated by finite element software package and user defined material subroutine. The project aims to reveal the failure mechanism of 3-D braided composites under low-velocity impact by experimental and finite element calculation results. To realize the structure parameters that have influences on the properties of low-velocity impact on 3-D braided composites. The best structural parameters of 3-D braided composites for low-velocity impact are investigated. Finally, the results will provide theory supports for the predication of mechanical properties and structure design of 3-D braided composites.

三维编织复合材料结构件应用范围日益广泛，但在制造、使用和维护过程中容易受到其他物体的低速冲击作用，导致内部结构损伤和承载能力下降甚至失效。本项目以三维编织复合材料为研究对象，采用实验和有限元相结合的方法，探索三维编织复合材料在低速冲击载荷条件下的动态响应特征。拟构建从纱线、编织物组织结构单胞到全尺寸三维编织物及其复合材料的多尺度细观结构模型；编写包含材料本构关系和失效准则的用户自定义材料子程序，结合商用有限元软件模拟三维编织复合材料低速冲击过程。本项目旨在通过实验和有限元计算在多尺度细观结构层次上，揭示三维编织复合材料在低速冲击加载条件下的失效机理；明确三维编织复合材料结构参数对其低速冲击力学性能的影响规律，提出抗低速冲击三维编织复合材料应具有的结构特征，为三维编织复合材料的开发和结构件优化设计奠定理论基础。

三维编织复合材料具有整体网状结构，相比层合复合材料加强了厚度方向力学性能，显著提高了层间剪切强度，在承受载荷特别是动态载荷时不会分层。三维编织复合材料在力学性能上体现为高强高模、高冲击损伤容限，广泛用于抗冲击结构件设计中。但是三维编织复合材料在制造、使用和维护过程中容易受到其他物体的低速冲击作用，导致内部结构损伤和承载能力下降甚至失效。本项目以三维编织复合材料为研究对象，采用实验和有限元相结合的方法，探索三维编织复合材料在低速冲击载荷条件下的动态响应特征。构建了从纱线、编织物组织结构单胞到全尺寸三维编织物及其复合材料的多尺度细观结构模型；编写了包含材料本构关系和失效准则的用户自定义材料子程序VUMAT，结合商用有限元软件ABAQUS模拟三维编织复合材料低速冲击过程。三维编织复合材料有限元计算载荷-位移曲线与实验结果吻合度较好，证明了单胞模型及用户子程序VUMAT的正确性和有效性。本项目通过实验和有限元计算在多尺度细观结构层次上发现，三维编织复合材料在低速冲击下最大载荷、最大载荷处能量以及吸收总能量均随冲击速度增加而增加。另外随冲击速度增加，失效模式也从弹性变形变为树脂开裂、纤维束与树脂脱粘直至最后纤维束断裂。本项目揭示了三维编织复合材料在低速冲击加载条件下的失效机理，为三维编织复合材料的开发和结构件优化设计奠定理论基础。