Mid‐Plane Symmetrical Bouligand Structural Design for Robust Multi‐Impact Resistance

Abstract The rapid advancement of aerospace, defense, and other fields has placed increasing demands on structural materials to deliver robust protective functions under extremely variable conditions, including impacts over a wide range of loading velocities and directions. However, traditional materials often face limitations in simultaneously achieving these properties. Herein, an advanced biomimetic carbon fiber‐reinforced composite material featuring a symmetric Bouligand (SB) structure is proposed. The SB structure combines mid‐plane symmetry to minimize residual stresses with mechanics‐driven optimization of inter‐ply angles to enhance interlaminar performance. This rational design endows the material with exceptional energy‐absorption capabilities, superior damage tolerance, and remarkable adaptability across a wide range of extreme impact conditions, including low‐velocity (LV), high‐velocity (HV), and oblique impacts. Experimental results demonstrate that the SB‐structured composites achieve a 277% increase in LV energy absorption and a 116% increase in HV ballistic limit compared with existing Bouligand‐structured composites; even oblique HV impacts on the SB‐structured composites lead to an extra 16% ballistic limit elevation. Computational simulations elucidate how the SB structure redistributes interlaminar shear stress, promotes beneficial crack twisting, and delays damage propagation. This biomimetic design framework provides a pathway for the development of next‐generation lightweight materials tailored for aerospace and other critical engineering applications.