Abstract A hierarchical multiscale framework has been developed to predict the impact response of 3D braided composites, in which a bridging model(unit cell model), was employed as a bridge between micro- and macro- scale. A paraboloidal elastic-to-plastic damage model for the epoxy, including the hydrostatic effect, was conducted, where a robust algorithm has been implemented to enhance the convergence and accuracy. At the microscale, nine RVEs (representative volume elements) with different fibers distributions were generated in order to enhance reliability and to reduce the size effect for the micromechanical analysis; At the macroscale, firstly, a unit cell model was proposed as a virtual meso-scale based on the geometric topology of 3D braided composites, and then the unit cell model was implicitly introduced into the macromodel based on the transformation matrix. The homogenization method was adopted for transferring the mechanical properties between scales. These constitutive models were implemented by two user defined subroutines (UMAT and VUMAT) in ABAQUS/Standard and ABAQUS/Explicit for micromechanical analysis and impact simulation, respectively. Furthermore, the failure envelop was carried out for matching a better strength criteria for the braiding yarn. Finally, the high-speed impact simulation was employed to validate the effectiveness of the multiscale framework. The results show that the numerical results are agreed with the experiments well.

中文翻译：

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用于分析 3D 编织复合材料冲击响应的分层多尺度策略

摘要 已经开发了一种分层多尺度框架来预测 3D 编织复合材料的冲击响应，其中使用桥接模型（晶胞模型）作为微观和宏观尺度之间的桥梁。进行了环氧树脂的抛物面弹塑性损伤模型，包括静水效应，其中已实施稳健算法以提高收敛性和准确性。在微观尺度上，为了提高可靠性并减少微观力学分析的尺寸效应，产生了九个具有不同纤维分布的 RVE（代表性体积元素）；在宏观尺度上，首先，基于 3D 编织复合材料的几何拓扑结构，提出了一个作为虚拟细观尺度的晶胞模型，然后基于变换矩阵将晶胞模型隐式引入到宏观模型中。采用均质化方法在尺度之间传递力学性能。这些本构模型分别由 ABAQUS/Standard 和 ABAQUS/Explicit 中的两个用户定义子程序（UMAT 和 VUMAT）实现，用于微观力学分析和冲击模拟。此外，为了匹配更好的编织纱线强度标准，进行了破坏包络。最后，采用高速冲击模拟来验证多尺度框架的有效性。结果表明，数值结果与实验吻合较好。这些本构模型分别由 ABAQUS/Standard 和 ABAQUS/Explicit 中的两个用户定义子程序（UMAT 和 VUMAT）实现，用于微观力学分析和冲击模拟。此外，为了匹配更好的编织纱线强度标准，进行了破坏包络。最后，采用高速冲击模拟来验证多尺度框架的有效性。结果表明，数值结果与实验吻合较好。这些本构模型分别由 ABAQUS/Standard 和 ABAQUS/Explicit 中的两个用户定义子程序（UMAT 和 VUMAT）实现，用于微观力学分析和冲击模拟。此外，为了匹配更好的编织纱线强度标准，进行了破坏包络。最后，采用高速冲击模拟来验证多尺度框架的有效性。结果表明，数值结果与实验吻合较好。采用高速冲击模拟来验证多尺度框架的有效性。结果表明，数值结果与实验吻合较好。采用高速冲击模拟来验证多尺度框架的有效性。结果表明，数值结果与实验吻合较好。