非主軸荷重下での織物複合材料の損傷進展解析

Abstract

In this study, a numerical method to estimate the mechanical behaviors of woven fabric composite under off-axis loading is proposed. Although FEM has been widely used for the estimation of mechanical behaviors or optimization of the FRP structure to save designing costs, mechanical behaviors, especially damage developments of fibrous composites under off-axis loading haven't been estimated by FEM because of the complex boundary conditions.As the FE method for woven fabric composite, unit cell with periodic boundary conditions has been used. In order to loading to off-axis direction of the unit cell, periodic boundary conditions based on relative displacement vectors are employed. The unit model is rotated so that loading direction become horizontal. The length of the relative displacement vectors can be calculated by the size of unit cell and loading angle. Poisson's effect is also considered in the method. The mechanical behaviors of arbitrary in-plane off-axis loading directions can be estimated by the proposed method. FE analysis based on damage mechanics was carried out and the damage behaviors of woven fabric composites under several loading directions were characterized. As the results, when the angle between loading direction and principal axis is larger, stress when initial damage occur decreased and damage of fiber bundle dominated by shear stress occurred. The proposed method will also contribute to analyze off-axis direction of other FRP with periodic boundary conditions such as braded composites or non-crimp fabric composites.