非理想界面桥联理论及横向压缩下基体的应力集中系数

项目名称： 非理想界面桥联理论及横向压缩下基体的应力集中系数

项目编号： No.11472192

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 数理科学和化学

项目作者： 黄争鸣

作者单位： 同济大学

项目金额： 110万元

中文摘要： 欲根据原始组分性能预报复合材料的破坏和强度，首先要正确计算纤维和基体中的内应力，其次须由基体的原始性能正确定义其现场强度输入数据，因为后者无法测量。桥联理论是目前少有的能计算任意载荷下纤维和基体中内应力的理论，但现有桥联理论建立在纤维和基体理想界面基础之上。只有确定了基体因添加纤维产生的应力集中系数，才可正确得到其现场强度。本项目有两个研究目的，一是建立非理想界面桥联理论，二是确定横向压缩下基体的应力集中系数。基于构造Mori-Tanaka-Eshelby桥联矩阵相同的CCA（同心圆柱）模型，在纤维和基体接触面上引入非理想界面条件，导出相应的无限大基体域桥联矩阵，再以此为参照创建有限基体域非理想界面弹-塑性桥联矩阵。通过对复合材料横向压缩破坏机理的实验表征和理论解析，准确确定横向压缩破坏面方程及基体应力集中系数，为实现由独立测试得到的纤维和基体性能预报复合材料强度这一梦寐以求目标夯实基础。

中文关键词： 纤维增强复合材料；本构理论；细观力学；破坏机理；力学性能

英文摘要： In order to predict failure behavior and ultimate strength of a fibrous composite only based on its original constituent material properties, the internal stresses in the constituent fiber and matrix must be accurately calculated. Moreover, input data for the in-situ strengths of the matrix must be defined upon its original properties, as the former are not measurable. The Bridging Model developed by the author of this project proposal is one of the few theories currently available which can be used to calculate internal stresses in the fiber and matrix of a composite subjected to any arbitrary load. However, the bridging model has been established based on a perfect bonding assumption for the fiber and matrix interface. Furthermore, only when the stress concentration factors in the matrix due to introduction of a fiber are determined, can the in-situ strengths of the matrix be available from its original counterparts. The purposes of this project proposal are in two folds. Firstly, the bridging model theory with an imperfect fiber/matrix interface will be established. Secondly, the stress concentration factor of the matrix in a composite subjected to a transverse compression will be derived. Very recently, by solving bridging equations correlating averaged stresses in the fiber and matrix of a CCA (coaxial fiber cylinder assembled within an unbounded matrix) model, exactly the same Mori-Tanaka-Eshelby bridging matrix with a perfect fiber/matrix interface bonding has been obtained by the author of this project proposal. The same approach will be employed in this project to derive a bridging matrix of an imperfect fiber/matrix interface for a composite with an unbounded matrix domain, as the stress fields in the fiber and matrix of a CCA model have been vastly investigated in the literature. The thus obtained bridging matrix will be used to benchmark the establishment of an elastic-plastic bridging matrix for a composite with an imperfect fiber/matrix interface. Through both experimental investigation and theoretical analysis for failure mechanisms of a composite under a transverse compression, the failure plane orientation will be precisely identified and the stress concentration factor in the matrix due to the transverse compression will be determined. With these two achievements, the basis for predicting a composite strength using independently measured fiber and matrix properties will be more soundly set up.

英文关键词： Fiber reinforced composites;Constitutive theory;Micromechanics;Failure mechanism;Mechanical property