Effect of Radial Clearance between Bolt and Washer on the Bearing Strength of Composite Bolted Joints

Abstract

When composite materials are bolted together, the relative diameters of the bolt hole, the constraining washer and the bolt itself have a profound effect on the ulti mate bearing strength. Previous studies have investigated the effects of clearance between the bolt and the hole diameter. In this study, the effect of the difference between the bolt diameter and the inside diameter of the washer, which provides the lateral constraint at the edge of the hole, is examined. To explain the significant variation of bearing strength with bolt-to-washer clearance, a model is proposed to explain the mechanics of load transfer and the lateral deformation at the edge of the hole. The test results, using a quasi-isotropic graphite epoxy laminate, support the proposed model and provide data for designers.