Elasto-plastic Stress Analysis at the Bearing Surfaces in Bolted Joints with Plain Washers under External Tensile Loadings

The characteristics of hollow cylindrical bolted joints with plain washers under external tensile loadings are analyzed using elasto-plastic FEM such as the contact stress distributions, plastic displacement (permanent set) at the bearing surfaces and the load factor. The difference in the contact stress distributions between the joints with the washer and without the washer is demonstrated. The effect of thickness of the plain washers on the contact stress distributions and the plastic displacements are clarified. It is found that the effect of the plain washer specified in JIS B 1256 is small on the contact stress distributions and the plastic displacements. Also, the effect of the external load on the changes in the contact stress distributions and the plastic displacements at the bearing surfaces using the values of load factor is observed to be small. It is also found that as the thickness and Young's modulus of the plain washer increases, the plastic displacement decreases. It can be concluded that the elasto-plastic FEM stress analysis is useful for analyzing bolted joints tightened with higher bolt preloads.