Optimum Design of Fibre Orientation Angles in Composite Laminate Plates for Minimum Thickness

Abstract

Previous studies have shown that composite fibre orientation angles can be optimised for specific load cases such as longitudinal or in-plane loading. However, the methodologies utilised in these studies cannot be used for general analysis of such problems. This research presents a methodology whereby the thickness of laminated composite plates is minimised by optimising the fibre orientation angles for different load cases. Therefore, the effect of transverse shear forces is considered in this study. Simulated annealing (SA), which is a type of stochastic optimisation method, is used to search for the optimal design. This optimisation algorithm has been shown to be reliable as it is not based on the starting point and it can escape from the local optimum points. In accordance with the annealing process where temperature decreases gradually, this algorithm converges to the global minimum. In this research, the Tsai-Wu failure and maximum stress criteria for composite laminate are chosen. Tsai-Wu failure is operationally simple and readily amenable to computational procedures. In addition, this criterion shows the difference between tensile and compressive strengths clearly, through its linear terms. By applying two failure criteria at the same time the results are more reliable. Finally, the numerical results are obtained and compared to the results of previous research with specific loadings to validate the methodology. Additionally the ply angles of composite plate are optimised by considering the effect of transverse shear force and induced twist angles.