Poro-elastic buckling performance of tapered higher-order functionally graded cellular beams encased in nanocomposite layers

This study aims to investigate the elastic buckling behavior of tapered sandwich beams with functionally graded cellular cores and carbon nanotube–reinforced facesheets. The main objective is to clarify how tapering, porosity distribution, and nanocomposite reinforcement influence the critical buckling load, thereby providing insights useful for the design of lightweight and mechanically efficient structural components. To achieve this, stress transformations at specific angles are performed to accurately determine the effective material properties corresponding to different reinforcement patterns along the beam thickness. The governing equilibrium equations are derived using the virtual displacement principle and the variational method, and are solved numerically by means of the differential quadrature method. A comprehensive parametric study is conducted to evaluate the effects of geometric characteristics, porosity coefficient, porosity distribution patterns, carbon nanotube reinforcement, and transformation angle on the critical buckling loads. The results demonstrate that tapered beams generally exhibit reduced buckling resistance compared to beams of uniform thickness, and that improper distribution of reinforcements along the thickness can lead to significant deviations in buckling performance.