A study of the force and moment resultants around quadrilateral hole in unsymmetric laminates

In this paper, with the development of the classical Lekhnitskii’s complex variable methods, stress analysis of unsymmetric laminated with a quadrilateral hole has been studied. By using the complex variable method, Lekhnitiskii obtained the stress distribution around a circular and elliptical hole in anisotropic plates. With the extension of this method to unsymmetric composite laminates and by using the conformal mapping, have tried to investigate the stress distribution around non-circular holes. In this article, the effect of various parameters such as aspect ratio of hole shape, hole orientation and bluntness on force and moment resultants around the hole is considered. The results of the effect of these parameters has been presented for [0/90]T and [-45/45]T layup. The finite element method is used to verify the results of the analytical solution. Analytical results are in good agreement with the finite element solution. Based on the analytical results. Unexpectedly circular hole is not the best geometry to reduce the stress concentration in perforated plates and in some cases by selecting the appropriate bluntness for quadrilateral hole, the stress concentration less than circular hole can be achieved. Also, by choosing an appropriate rotation angle and selecting the proper fiber angle for each layer, the stress and moment resultants around the hole can be significantly reduced.