A design methodology for mechanically fastened joints in laminated composite materials

This paper presents a new methodology to predict the onset of damage, final failure and failure mode of mechanically fastened joints in composite laminates. The stress distribution at each ply is obtained using semi-analytical or numerical methods. The elastic limit of the joint is predicted using the ply strengths and stress distribution in failure criteria. Final failure and failure mode are predicted using point or average stress models. Standardized procedures to measure the characteristic distances used in the point or average stress models are proposed. The methodology proposed is applicable in double-shear joints using quasi-isotropic laminates. The predictions are compared with experimental data obtained in pin- and bolt-loaded joints, and the results indicate that the methodology proposed can accurately and effectively predict ultimate failure loads as well as failure modes in composite bolted joints.