Finite Element Analysis of the Mechanical Behavior of Multi-Bolted Joints Subjected to Shear Loads

When subjected to external forces, bolted joints behave in a complex manner especially in the case of the joints being clamped with multiple bolts. Friction type joints are widely used for the joints subjected to shear loads. Bearing type joints, which support the shear load on the surface of bolt body, are used less frequently, since its mechanical behavior is too complicated to accurately estimate the load capacity. In this study, mechanical behavior of multi-bolted joints subjected to shear loads is comprehensively analyzed by three-dimensional FEM. Load distribution patterns of the bearing type joint are compared to those of the friction type joint. It has been found that the shear load applied to a bearing type joint distributes with a concave shape along the load direction as clamping bolts are increased, and a fair amount of the shear load is also supported by friction. Additionally, a simple method that calculates the shear load distribution is proposed using elementary theory of solid mechanics, which can estimate the shear load distribution with sufficient accuracy for the case of small friction coefficient.