A HIERACHICAL MULTISCALE MODEL FOR IN-PLANE MECHANICAL STRENGTH OF STITCHED COMPOSITE LAMINATES

摘要

The contribution attempts to model the alteration of the in-plane elastic properties in laminates caused by stitching. The distortion of in-plane fibers is considered to be the main reason that influences the in-plane mechanical properties. The fiber distortion model is proposed to characterize the fiber misalignment and the fiber content concentration caused by stitching. The undistorted region, the fiber distortion region, the resin-rich pocket and the through-thickness reinforcement section are taken into account. The fiber misalignment and the inhomogeneous fiber content caused by stitching have been formulated by introducing two parameters, i.e. distortion width w and maximum misalignment Φ{sub}0. Then the in-plane strength of the stitched composite laminate are formulated based on the assumption that the stitched laminate fails when the average value of the ratio of longitudinal stress to strength in the 0-deg lamina over a characteristic length, l{sub}0, away from the stitch hole is equal to the unit.