Free Vibration and Buckling Behaviour of Laminated Composite Panel under Thermal and Mechanical Loading

Abstract

Laminated composites have been used in various industries such as aerospace, mechanical, chemical, space craft and other high performance engineering applications. This in turn created the requirement of analysis of these structures/structural components through mathematical, experimental and/or simulation based model for accurate design and subsequent manufacturing. These structures are exposed to large acoustic, vibration, inertia excitation as well as unlike environmental condition during their service life. The elevated thermal loading often changes the original geometry of the panel due to excess deformation and the final structural performance affected greatly. The first mode of vibration/fundamental frequency is always associated with high amplitude and it causes large tension and/or compression which leads to fatigue of the structural component. Therefore, the vibration analysis of laminated structures made-up of composite and/or hybrid materials becomes significant. In general, buckling is the state of geometrical instability of the structure induced by the in-plane thermal/mechanical/thermo-mechanical forces. It is important to mention that, the geometric strain associated with buckling is always nonlinear in nature. In this study a general mathematical model is developed for laminated composite single/doubly curved (cylindrical/ spherical/ hyperboloid/ elliptical) panel in the framework of higher order shear deformation theory. The geometrical distortion of the laminated panels due to in-plane (thermal/mechanical/thermo-mechanical) load have been incorporated through Green-Lagrange nonlinearity to count the exact flexure. The developed mathematical model has been discretised using suitable finite element steps to obtain the sets of algebraic equations for the domain. The equations are solved through a computer code developed in MATLAB environment to obtain the desired solutions. In addition to this, a simulation model have been developed in ANSYS for all different cases and the responses are checked to show the generality of the present developed model. The effects of thickness ratio, aspect ratio, curvature ratio, modular ratio, stacking sequence, number of layer and support condition and the material properties on the vibration and the buckling responses are studied in detail.