Experimental and theoretical investigation of the low velocity impact response of CFRP composite beams

• Experimental and theoretical study on CFRP beams under LVI. • 3 distinct response regimes identified: elastic, damage, and complete collapse. • Force and energy curves reveal critical transitions in impact response. • A proposed model effectively captures impact response • The model identifies an auxiliary energy absorption mechanism. • Findings contribute to enhanced guidelines for impact-resistant composite structures. This paper presents an investigation into the low-velocity impact (LVI) behavior of carbon fiber reinforced polymer (CFRP) composite beams. The main goal is to explore the experimental and theoretical responses of woven CFRP composites under LVI loading. To simplify the typically complex geometries of composite structures, this study focuses on beam configurations rather than plates. The effects of impact energy on damage characteristics, peak load, and energy absorption are comprehensively analyzed. The force and energy curves exhibit three distinct behaviors across varying impact levels. Elastic behavior is evident at impact energies of 2, 5, and 7.5 J. The damage threshold in terms of force, displacement, and energy for the composite beam is demonstrated at intermediate impact levels of 10, 12.5, and 15 J. At the highest impact levels of 17.5 and 20 J, the specimen undergoes complete collapse, as indicated by a sharp drop in the force-time curves, open-loop force-displacement curves, and a continuous increase in the energy-displacement curves without a descending path. The absorbed energy by the composite beam demonstrates distinct behaviors across the low, intermediate, and high impact energy ranges. A damage-based theoretical model has been proposed that effectively captures the key characteristics of the beam’s impact response. In addition to the damage mechanism, the model reveals the presence of an auxiliary energy absorption mechanism that operates concurrently. Notably, this secondary mechanism persists across all levels of impact energy, including those within the lowest range. The findings provide valuable insights for enhancing simulation accuracy for impact-resistant composite structures.