Metamaterial based car bumper using carbon fiber reinforced polymer composite to improved energy absorption: An experimental study

The study investigates the development of a continuous carbon fiber reinforced polymer (CFRP) composites mechanical metamaterial that exhibits Negative Poisson’s ratio (NPR) properties, designed for higher energy absorption, suitable for automotive bumper materials to withstand the impacts. The objective is to search a proper parametric design with spring-type compression microstructures with gradually stiffer (GS) property and followed by experimental investigation of the properties of the designed structure. Finite element analysis is employed for the integration of high stiffness, auxetic properties, and enhanced failure resistance in the proposed design for lightweight, energy-absorbing structures in crashworthy automotive applications. AHP-TOPSIS multi-criteria decision-making method optimized geometrical variables strut angle (ϴ = 65°), strut length ( L = 10mm), and strut width ( b = 4 mm) based on performance parameters such as stiffness, strain energy, NPR, and total strain from the simulated results. Quasi-static compression testing on the fabricated structure validated auxetic behavior, resulting in an experimental Poisson’s ratio of −0.36 and stiffness of 1.24 N/mm, which closely aligns with simulation results. The findings from the quasi-static test indicate that the metamaterial exhibits remarkable reusability characteristics and effective energy absorption capability. High-resolution SEM and macroscopic imaging identified several progressive damage modes, such as fiber pull-out, interlaminar delamination, and matrix cracking, which suggest significant energy absorption and structural resilience. The close alignment between simulation and experimental data confirms the mechanical integrity and modeling precision of the CFRP-based metamaterial.