Strength of Bolted Joints in Composites under Concentrated Moment

Abstract

Rigid mechanical fasteners in transversely isotropic composite panels create large stress concentrations in the composite near the fastener washers. The work presented in this paper involved an experimental strain investigation to obtain the distribution of strain in the composite near the edge of the washer and a failure investigation to determine the onset-of-failure moment and the catastrophic-failure moment for various washer designs. The flexural rigidity of the washer was shown to be important for obtaining both high onset-of-failure moments and catastrophic-failure moments. Washers with large shoulder radii were shown to have higher catastrophic-failure moments. The experimentally determined strain distributions and the results of the failure investigation with 25.4 mm diameter rigid washers were used to validate finite element models.