短纤维增强复合材料（MMC）的蠕变损伤失效的微观数值模拟

Micro Numerical Simulation of Creep Damage and Failure of Short Fiber Reinforced Metal Matrix Composites (MMCs)

摘要:

研究了短纤维增强复合材料（MMC）的蠕变损伤和失效的细观机理.采用微胞模型结合有限元软件ABAQUS进行.基体的损伤失效由K-R模型描述,纤维断裂由应力准则控制,它们已分别作为用户子程序编入到ABAQUS中.有限元分析表明,在纤维断裂前损伤主要位于纤维头顶角附近,断裂后集中在纤维断裂面附近.纤维断裂对基体蠕变损伤影响有限,但是断面附近产生很高的应力集中,该应力集中将有助于裂纹在基体中的发展.

Abstract:

The mechanisms of the creep damage and the failure of the short fiber reinforced metal matrix composites (MMCs) have been investigated. The unit cell models are applied for the plane randomly-distributed-fiber MMCs by means of the finite element method (FEM) of ABAQUS. The creep damage and failure of the matrix is simulated by the K-R damage model, which has been implemented as the user subroutine CREEP of ABAQUS. The breakage of the fibers is simulated by the stress criterion, it means that the breakage will occur when the axial stress of the fibers reaches the critical value. This stress criterion has also been implemented into the ABAQUS. The influence of the fiber breakage on the stress distribution has been obtained. The FEM results show that the creep damage is localized near the corners of the fibers and the fractured surfaces of the fibers after the breakages of the fibers occur. And the fiber breakage has very limited influence on the creep damage of the matrix, but it reduces a high stress concentration in the matrix near the fractured surface. This high stress concentration will help the crack enlargement in the matrix by the stress criterions.