PROGRESSIVE FAILURE ANALYSIS OF FIBER STEERING COMPOSITE STRUCTURES WITH A HOLE

Abstract

The application of fiber steering to composite structures is expected to reduce the stress concentration around a hole and to improve overall strength. The objective of this study is to establish an optimal design method for fiber steering composite structures with an open hole, with the consideration of damage progression. In this study, fiber steering is applied to 0° layers of a panel with an open hole under uniaxial tensile load by aligning the fiber steering direction to the maximum principal stress direction. Parametric studies of 1500 panel models with different hole geometries are performed by finite element analysis for both quasi-isotropic models and fiber steered models. The effect of the geometry change of the hole on failure load of the composite structure is investigated with progressive failure analysis based on Hashin’s failure criteria. In addition, the effect of hole geometry on performance of the fiber steering is also investigated. In most models, two stages of damage progression are observed. Result of the parametric study shows that failure load has increased with decreasing curvature of the hole. The smaller curvature of the hole around the point of origin of the failure reduces stress concentration and increases the maximum load. When fiber steering is applied, models with high strength are less sensitive to fiber steering. This is because the curvature of the hole around the stress concentration area is small, and the fiber orientation is straight. It is suggested that the curvature of the hole may influence the strength enhancement effect of fiber steering.