Progressive Damage Effects of Low‐Velocity Impact Fatigue on Intra‐Ply Carbon/Basalt Fiber Reinforced Composites

ABSTRACT The current research examines the low‐velocity impact fatigue behavior of intra‐ply Carbon/Basalt Fiber Reinforced Polymer (CBFRP) laminates fabricated using the Vacuum Assisted Resin Infusion Molding (VARIM) technique. Repeated drop‐weight impact tests were conducted at a controlled energy level to evaluate the evolution of mechanical degradation, stiffness loss, and vibration response under progressive damage. Contact force–time histories revealed a transition from an initially elastic response at low cycle counts to a damage‐dominated response at higher cycles. This phenomenon was characterized by reduced peak force, extended interaction duration, and increased oscillation due to unstable load transfer. Mechanical characterization also showed systematic reductions in elasticity modulus, tensile strength, flexural modulus, interlaminar shear strength (ILSS), and buckling critical load, confirming that repeated impacts weaken both in‐plane and interlaminar performance. Modal testing under clamped‐free and free‐free boundary conditions demonstrated decreasing natural frequencies and increasing damping ratios with rising cycle number, reflecting stiffness degradation and enhanced internal friction associated with damage growth. Absorbed energy increased steadily as repeated impacts promoted matrix cracking, interfacial debonding, delamination, fiber pull‐out, and ultimately fiber fracture, as confirmed through detailed post‐impact fractographic examination. These observations indicate a hierarchical progression of damage mechanisms responsible for long‐term deterioration in hybrid composite performance.