Damage Mechanism and Residual Strength Prediction on Low‐Velocity Impact Tests of Carbon Fiber Composites With Different Layup Structures

ABSTRACT Carbon‐fiber‐reinforced Polymer Composites are extensively utilized in impact‐prone structures due to their high specific stiffness and strength. In this paper, the effects of layup structure and impact energy on low‐velocity impact response and post‐impact residual compressive strength were evaluated, and their quantitative relationships were established using regression analysis. Carbon fiber composites with [0°/90°] ₂₀ and [(+45°/−45°)/(0°/90°)] _10s layup structures were fabricated by Vacuum Assisted Resin Infusion (VARI) and tested under 20 to 50 J impacts. The analysis reveals that the [(+45°/−45°)/(0°/90°)] _10s laminate dissipates impact energy at lower levels mainly through matrix cracking, delamination growth and ±45° shear slip with pronounced interfacial friction, whereas beyond an approximate 40 J threshold the [0°/90°] ₂₀ laminate exhibits fiber‐dominated energy dissipation and better preservation of structural integrity. At 20 and 30 J [(+45°/−45°)/(0°/90°)] _10s retains 10.50% and 6.80% more CAI strength than [0°/90°] ₂₀ , whereas at 40 and 50 J [0°/90°] ₂₀ has a 7.5% and 5.78% higher peak force, respectively. Ridge regression identifies the maximum displacement and the damage area as the critical descriptors of the residual strength percentage. This study elucidates the coupled effects of layup configuration and impact energy on damage evolution in composites and provides a framework for optimizing composite design.