内聚力界面单元与复合材料的界面损伤分析

COHESIVE INTERFACE ELEMENT AND INTERFACIAL DAMAGE ANALYSIS OF COMPOSITES 1)

推导了一种基于内聚力模型无厚的界面单元，用来模拟复合材料纤维与基体之间的界面层．研究了纤维周期分布的复合材料受横向荷载时。

An interface element based on the cohesive zone model is employed to simulate the fiber/matrix interface in composite. The cohesive zone model used here is viewed as a phenomenological model. A potential function is adopted to describe the relationship between the interface traction and the interface displacement jump. Two sets of interface parameters are adopted to represent the interface strength and toughness respectively. This model can simulate the evolution of interface damages, which are coupled in the normal and tangential directions. The interface element has no thickness initially. This interface damage model is performed to composites which have periodic array of fibers and are subjected to a transverse load. For symmetry, the computational representative element (RVE) contains a quarter of fiber. The fiber is assumed as elastic material and its stiffness is much higher than that of the matrix material. The matrix is assumed as isotropic hardening elastic plastic material. Finite deformation is considered. The interface damage evolution and its effect on the properties of composites under the conditions of various interface strengths and toughness is investigated. The results show that the debonding starts at the polar region of the fiber and moves to the equator region with the loading increasing. The average tensile stress on the RVE drops when the debonding takes place. Large interface strength brings on the delayed interface debonding and the high ultimate tensile strength. With the same interface strength, the high interface toughness means the low interface stiffness and high energy to separate the interface. So the debonding initiation and evolution are retarded in case of the high interface toughness. The maximum normal displacement jump is at the polar region of the fiber and the maximum tangent displacement jump is near the region of θ=π/4 . In short, the interface strength and toughness are beneficial to the interface debonding resistance capacity and the strength of the composite.