Effects of friction on three-dimensional contact stresses in pin-loaded laminated composites

An investigation is performed to study the effects of friction on the three -dimensional (3D) stress state around pin-loaded holes in laminated composi tes. The composite pinned joints are modeled as a linear elastic contact pr oblem with friction; therefore, the interactions between the pin with the l aminate follow the law of Coulomb friction. An analytical solution for the 3D stress state involved in this problem is developed based upon the variat ional principle of complementary energy. Compared to the previous research based on a two-dimensional stress assumption, the present solution is innov ative, since the out-of-plane effects (i.e., edge effects) near the pin-loa ded holes are considered. The present formulations are restricted to the la minated composites with bi-directional fiber orientations, because all the traction and displacement boundary conditions can be satisfied in such type of laminates. Numerical results for pin-loaded cross-ply laminates with di fferent coefficients of friction are presented. It is shown that the effect s of friction on the magnitude and distribution of the 3D stress state arou nd pin-loaded holes in laminated composites are significant.