Comparative Study on Low‐Velocity Impact Behavior of Quasi‐Isotropic and Double‐Double Carbon Fiber/Epoxy Laminates

ABSTRACT The evolution of double‐double (DD) laminates is a promising substitute for traditional quasi‐isotropic laminates due to their potential for lower interlaminar stresses and enhanced design flexibility. The present work investigates the low‐velocity impact (LVI) response of carbon fiber/epoxy composites experimentally and numerically. One quadriaxial (QUAD) layup and three similar DD configurations denoted by DI, DII, and DIII were tested at impact energies of 10 and 20 J. A finite element model was established to systematically investigate the LVI behavior and damage mechanisms of the DD laminates. Mesh convergence and sensitivity analysis were also conducted. The simulated peak force and maximum displacement were compared with the experimental data to validate the model. The model predictions agreed well with the experimental data, with an average error of about 8%. It is shown that the DD laminates have different impact behavior as compared to the QUAD despite having the same in‐plane stiffness. The DII configuration exhibited the highest energy absorption and largest delamination area, while DI exhibited the lowest energy absorption, indicating a better elastic recovery and least permanent damage. Ultrasonic C‐scan, Hashin matrix tensile damage, and matrix compression damage contours showed that layup sequence and coupling effects have a significant impact on the damage distribution and delamination extent. The reported results offer useful information for the design of composite structures subjected to LVI, particularly regarding energy absorption and damage morphology.