title: Analytical Study of Two Pin-Loaded Holes in Unidirectional Fiber-Reinforced Composites.
abstract: The objective of this paper is to investigate the effects of geometrical parameters such as the edge distance-to-hole diameter ratio {e/d}, plate width-to-hole diameter ratio {w/d}, and the distance between two holes-to-hole diameter ratio {l/d} on stress distribution in a unidirectional composite laminate with two serial pin-loaded holes, analytically and numerically. It is assumed that all short and long fibers lie in one direction while loaded by a force poat infinity. To derive differential equations based on a shear lag model, a hexagonal fiber-array model is considered. The resulting pin loads on composite plate are modeled through a series of spring elements accounting for pin elasticity. The analytical solutions are, moreover, compared with the detailed 3D finite element values. A close match is observed between the two methods. The presence of the pins on shear stress distribution in the laminate is also examined for various pin diameters.
authors.affiliation: Department of Mechanics, Hamadan Branch, Islamic Azad University , Hamadan , Iran e-mail:  Attarmm2010@yahoo.com.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Mahdi Attar