Abstract A multiscale elasto-plastic damage model is developed to predict the nonlinear behavior of three-dimensional (3D) braided composites. In this model, the sequential multiscale method is applied to transfer the effective properties from microscale to mesoscale, and from mesoscale to macroscale. The constituents at the microscale consist of fiber, matrix and interface which are consistent with the mesoscale ones. The fiber is considered to be elastic and brittle, and the elastic damage model is applied to degrade the stiffness. For the epoxy matrix, a coupled elasto-plastic damage model is proposed to integrate the effects of plasticity and damage, and furthermore the paraboloidal yield criterion is adopted to characterize the different types of mechanical behavior in tension and compression. The bilinear constitutive relation based on the cohesive element is used to investigate the properties of interface. A user-defined material subroutine (UMAT) in the nonlinear finite element analysis software ABAQUS is written to implement the proposed model and determine the response for 3D braided composites under quasi-static tension. The numerical simulations are compared with the corresponding experiments and the results show that they agree well with each other.

中文翻译：

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用于 3D 编织复合材料非线性行为的多尺度弹塑性损伤模型

摘要 开发了一种多尺度弹塑性损伤模型来预测三维 (3D) 编织复合材料的非线性行为。在该模型中，应用顺序多尺度方法将有效属性从微观尺度转移到中尺度，从中尺度转移到宏观尺度。微观尺度的成分由纤维、基体和界面组成，与中尺度一致。纤维被认为是弹性和脆性的，应用弹性损伤模型来降低刚度。对于环氧树脂基体，提出了一种耦合弹塑性损伤模型来整合塑性和损伤的影响，并采用抛物线屈服准则来表征不同类型的拉伸和压缩力学行为。基于内聚元的双线性本构关系用于研究界面性质。编写了非线性有限元分析软件 ABAQUS 中的用户定义材料子程序 (UMAT) 来实现所提出的模型并确定准静态张力下 3D 编织复合材料的响应。数值模拟与相应的实验进行了比较，结果表明它们相互吻合。