Approximate Stress Analysis and Stress Failure Models

Approximate stress analyses are presented for orthotropic composite laminates containing an elliptical opening under uniaxial normal loads. Utilizing the elasticity solutions, the point stress failure model and the average stress failure model are generalized for the strength prediction of fiber-reinforced composite laminates containing an elliptical opening. This chapter extends the point stress and the average stress failure models to the case of elliptical openings. Approximate stress analyses on the axis normal to the applied stress are derived using a similar approach as Konish and Whitney's. A number of articles for the stress analysis and experiments with isotropic plates containing an elliptical opening can be found in the References. Based on the point stress failure model, it is assumed that the laminate would fail when the stress at some distance, d°, away from the opening edge and on the axis normal to the loading reaches the unnotched laminate strength.