Stress Analysis of a Pin and Clevis Assembly

The shear yield strength of the material is one of the controlling factors in determining the pin diameters for a pin and clevis connection. Typically, for steels used in machine fabrication, an accepted method is to approximate the shear yield strength as 75% of the material’s ultimate tensile strength Blodgett [1]. In a pin and clevis connection, the pin can be subjected to static and dynamic loads that can generate stresses on the order of the shear yield strength of the steel. The loads produce bending and shear stresses in the pin. The highest stressed region is the clearance gap between the blade and clevis. Finite Element Analysis (FEA) results produced valuable insight into the problem. The various methods available to constrain the computer models produced different results. Enhanced FEA computer models provided the most realistic insight into the actual pin stresses. Full-scale steel test hardware was tested with static loads until pin failure occurred. A standardized pin size of 12.7 mm (0.500 in) diameter was used in order to maintain the loads at a manageable testing level. Strain gages placed in the clearance gap recorded bending strains. The pins failed from shear stress in the area of the gap region.