Influence of thermo-mechanical loads on variable stiffness composite beams: a comprehensive study using semi-analytical and finite element approaches

This study investigates the stability and vibration characteristics of variable stiffness laminated composite (VSLC) beams subjected to thermo-mechanical loadings. A semi-analytical model is developed to determine the buckling and vibration characteristics of variable stiffness composite beams. The model employs a displacement-based Ritz approach to derive the matrix representation of the governing equations. Modified constitutive relations are derived to account for the Poisson effects that arise due to the development of zero-stress conditions in the width direction of beams. The material properties and temperature variations are assumed to be constant across the thickness of the beam. Moreover, finite element calculations are carried out using commercial software ABAQUS in conjunction with a MATLAB-generated input file, which is utilized to capture fiber angle variations within the beam. Numerical results are obtained to elucidate the effect of slenderness ratio, modulus of elasticity ratio, boundary conditions, number of layers, and ply-sequence on the free vibration and instability characteristics of VSLC beams subjected to mechanical loadings and thermal environments. This study underscores the crucial importance of taking these factors into account for precise and dependable design and analysis of such composite beams in engineering applications.