A refined couple stress model for size-dependent thermo-mechanical analysis of laminated composite microplates

The present work develops a novel size-dependent analytical framework for analyzing the thermo-mechanical behavior of laminated microplates by combining a refined couple stress model with an inverse-hyperbolic plate theory. The formulation captures anisotropic material characteristics while incorporating size dependency through an intrinsic length-scaling parameter aligned with the fiber orientation angle of the laminate. The use of the inverse-hyperbolic shear deformation function provides an improved representation of transverse shear behavior without requiring shear correction factors, offering a distinct advantage over conventional higher-order shear deformation theories. Using the principle of virtual work, the governing equations are established and solved using Navier’s closed-form technique under simply supported boundary conditions. An extensive parametric investigation is conducted to examine the effects of micro-scale shear deformation and thermal loads on the bending characteristics of micro-laminates. The results show that the inclusion of couple stress effects leads to a reduction in deflection of up to approximately 40%, while thermal loading further contributes to reductions of about 12–63% depending on the loading and geometric parameters. Additionally, the model converges to classical plate theory predictions at small length-scale values, validating its accuracy. The inverse-hyperbolic shear deformation model shows strong agreement with higher-order shear deformation theories without requiring shear correction factors. Overall, the comparative results validate the model’s accuracy and efficiency, establishing it as a comprehensive analytical framework for assessing the performance of numerical methods in the analysis and design of advanced micro-scale systems, including micro-electromechanical systems (MEMS), where precise prediction of thermo-mechanical deformation is critical for the reliability of sensors, actuators, and micro-structural components, where conventional plate theories fail to capture size-dependent effects.