Effect of the Aspect Ratio on the Buckling Load of Unidirectional Carbon Fiber Reinforced Composites

Abstract

Elastic instabilities, such as buckling and snapping-through, serve as key mechanisms in metamaterials and periodic structures designed for self-centering, energy absorption, and dissipation. These systems rely on single or multiple buckling events of interconnected axially compressed elements. A promising candidate material for such elements is the unidirectional carbon fiber-reinforced composites, provided that elastic buckling precedes inelastic damage failure. This study presents a numerical investigation to examine the failure stress of unidirectional carbon fiber-reinforced composites with various aspect ratios (AR). Finite element analyses were performed on tested specimens of unidirectional carbon fiber-reinforced polymer composites found in the literature. Results indicate that a minimum AR of 28 is required to induce buckling failure rather than other modes, with Euler’s equation sufficiently predicting critical buckling stress in this range. On the other hand, for AR values between 15 and 28, compression-shear or shear failure becomes dominant, while AR below 15 typically results in compression failure. Accounting for shear correction and material nonlinearity enables precise prediction of critical buckling stress across all AR.