Comparative Analysis of Post‐Buckling Torsional Response in Carbon/Aramid Hybrid and Carbon Fiber Composites: Experimental Evaluation of Synergistic Effects Beyond Macro‐Scale Modeling Limits

Abstract

This study investigates the buckling and post‐buckling performance of Carbon Fiber Reinforced Epoxy (CFRE) and intraply Carbon/Aramid Fabric Reinforced Epoxy (C/AFRE) composite plates through an integrated experimental and numerical approach. A repeatable two‐phase testing procedure that utilizes a programmable control logic for real‐time buckling detection is used to determine the onset buckling and immediately measure the post‐buckling torsional behavior. The algorithm monitors the Percent Stiffness Deviation Variable derived from a Linear Least Square Regression of the axial load–displacement response, automatically triggering the transition from compressive to torsional loading upon reaching a 10% stiffness reduction threshold. Experimental results were used to validate a Finite Element Analysis (FEA) framework developed in ABAQUS/Standard. While the FEA model demonstrated high accuracy for CFRE specimens, it overestimated the post‐buckling stiffness reduction for the hybrid C/AFRE laminates. This localized enhancement in post‐buckling integrity, which was absent in the pure carbon fiber samples, serves as an indicator of possible intraply synergistic interactions that the macro‐scale models failed to anticipate. The results highlight the effectiveness of the proposed real‐time detection methodology and suggest that higher‐fidelity, meso‐scale modeling is necessary to fully capture the post‐buckling behavior of intraply hybrid composites.