Effect of Stacking Sequence on the Low-Velocity Impact Behaviour of T300/5208 Carbon/Epoxy Laminates: An Intralaminar Hashin-CDM Based Numerical Study of Eight Configurations

Carbon fiber reinforced polymer (CFRP) laminates are widely preferred in aerospace and transportation structures owing to their high specific strength and stiffness; however, they exhibit a pronounced sensitivity to out-of-plane low-velocity impact (LVI) loads. In this study, the effect of stacking sequence on the LVI response of T300/5208 CFRP laminates was investigated numerically. Eight stacking configurations (L1–L8), all 125 × 75 mm in size, 5 mm thick and consisting of 40 plies, were defined; unidirectional, cross-ply, angle-ply, quasi-isotropic, multidirectional, hybrid and blocked quasi-isotropic architectures were compared at a single controlled energy level. A hemispherical impactor with a mass of 5.5 kg was applied at an initial velocity of 2.468 m/s and an energy of 16.75 J. Numerical solutions were performed in Abaqus/Explicit using SC8R continuum shell elements together with the Hashin initiation criterion and an energy-based continuum damage mechanics (Hashin-CDM) framework; interlaminar separation was deliberately excluded within an intralaminar-only model. The geometry and post-processing were established on the basis of ASTM D7136. The results showed that the stacking sequence produced differences of about 53% in peak contact force, 38% in maximum displacement and 40% in permanently absorbed energy. The highest contact force and the smallest displacement were obtained for the cross-ply L3 (8964 N; 3.507 mm), whereas the lowest force and the largest displacement occurred for the unidirectional L2 (5863 N; 4.836 mm). In terms of permanent energy absorption, the angle-ply L4 reached the highest value (12.081 J). In all configurations, the dominant damage indicator was matrix tension damage (DAMAGEMT), and the damage orientations were consistent with the fiber directions. The results demonstrate that, through an appropriate choice of stacking sequence, the stiffness–energy absorption balance of the laminate under impact can be controlled.