Strain Rate Effects on the Compressive Behavior of Unidirectional CFRP

ABSTRACT This study investigates the strain‐rate‐dependent compressive behavior of unidirectional CFRP composites through experimental and numerical approaches. Using SHPB testing, we systematically characterize dynamic responses along three principal directions (along fiber, transverse, and through‐thickness) under stress equilibrium and constant strain‐rate conditions (10 ⁻³ –10 ³ s ⁻¹ ). Results reveal significant strain‐rate strengthening effects, with 72%, 68%, and 76% strength enhancements in fiber, transverse, and through‐thickness directions, respectively, at high strain rates. A novel strain‐energy‐based constitutive model is developed, incorporating coupled evolution of strength and failure strain energy density with strain rate. The model demonstrates exceptional accuracy, achieving < 3% error in strength prediction and < 10% in energy absorption across the tested strain‐rate spectrum. These findings provide fundamental insights for improving impact‐resistant composite design.