Effects of Off-Axis Angle and Layer Thickness on the Compressive Strength of Cross-Ply CFRP Laminates

Abstract

The effects of off-axis angle and layer thickness on the compressive behavior of cross-ply carbon fiber reinforced plastic (CFRP) laminates were examined through experimental and numerical approaches. Two kinds of cross-ply carbon fiber/epoxy laminates, namely [90°/0°]4s, and [90°2/0°2]2s were prepared. The layer thickness was 0.14 mm for [90°/0°]4s, and 0.28 mm for [90°2 /0°2]2s, respectively. The off-axis angles were 0°, 2°, and 4°. Compressive tests were conducted in accordance with ASTM-D6641. The compressive strength and the longitudinal elastic modulus decreased with increasing the off-axis angle. Layer thickness had a little effect on compressive strength. As numerical approach, finite element analysis (FEA) was conducted by employing the Christensen’s failure criterion. The numerical results imply that application of the Christensen’s failure criterion to FEA be able to estimate the reduction in elastic moduli and compressive strength with increasing off-axis angle. Contrary to the experimental results, compressive strength estimated by FEA increased with increasing layer thickness. This implies that the dependence of fiber-direction strength on layer thickness should be taken into consideration for FEA.