The Effect of Fiber Arrangement on Stress Concentration Around a Pin in a Laminated Composite Joint

This paper analytically investigates the effect of fiber arrangements on stress distribution around a pin joint in a laminated composite. It is assumed that all fibers lie in one direction while loaded by a force p_o at infinity. According to the shear lag model, equilibrium equations are derived for two types of fiber arrangements. In the first model, a square arrangement is selected for the fibers, while in the second; a hexagonal arrangement is used to deduce the equilibrium equations. Upon proper use of boundary and boundness conditions, stress and displacement fields are derived within the laminate and their peak values are determined on the compressive side of the pin periphery. The effect of pin diameter on stress concentration around the pin is well examined. The presence of the pin on shear stress distribution in the laminate is also examined for various pin diameters. According to the results, a square arrangement of fibers results in smaller values of stress concentrations around the pin, as compared to those of a hexagonal arrangement. The pin position and its diameter shows to have noticeable effect on both normal and shear stresses developed within the laminate, as well as pin surrounding.