Effects of anisotropy and off‐axis angle on buckling behavior of carbon/epoxy Z‐pin under axial pressure

Abstract

AbstractThe axial buckling load of single carbon fiber or composite strands is typically predicted using Euler's formula, developed for isotropic materials. This study introduces anisotropy in a mechanical carbon/epoxy Z‐pin model under axial pressure. It examines the influence of compressive modulus, shear modulus, off‐axis angle, and aspect ratio on its buckling behavior. Results show that the axial instability performance of the Z‐pin decreases with lower compression, shear modulus, and aspect ratio while keeping the tensile modulus fixed. Anisotropy decreases buckling load by up to 14% compared with Euler's formula, which only considers tensile modulus. Additionally, the impact of the deflection Angle between the pressure and pin‐axis can be ignored when it is less than 3°.Highlights Euler formula overestimates composite Z‐pin buckling force under axial pressure. Anisotropy decreases buckling load by up to 14% for carbon/epoxy. Shear modulus is more influential on Z‐pin with a small aspect ratio. For off‐axial compression angles <3°, influence can be ignored.