Stresses of Composite Laminates Containing Holes and Cracks

Abstract

Stress functions for anisotropic plates, containing 3 holes and subjected to plane stress, were derived using complex variables and superpositioning the solutions of one and two hole plates. MacLaurin series expansion was used to calculate the stresses around the contour of the openings. Effects of openings’ sizes, shapes, and relative positions on stress concentration factors were investigated. Results indicated that adjacent holes may be ignored if the distance between the center of the openings is at least five times the length of the major axis of the openings. Also, the SCF of a circular hole, located between the larger and a smaller hole, was affected more by the presence of the larger hole. For an elliptical hole located between an elliptical hole and a circular hole, the circular hole exerted more influence on the SCF of the elliptical hole when the plate was under vertical tension. Under bi-axial tension, the other elliptical hole had greater influence on the SCF of the center elliptical hole. When the holes were arranged in triangular pattern, the SCF decreased as the angle between the holes increased. By reducing the ratio of the major and minor axis of the elliptical holes, the influence between cracks was also studied.