A plane strain elastic-viscoplastic-based finite element model is developed to simulate a composite system with sinusoidal corrugated cores under tensile loading conditions. Numerical study shows that the rate sensitivity in the reinforced core provides a positive impact on loading capacity, the necking strain retardation, and improvement in the ductility of a composite. By carefully selecting the reinforced sinusoidal core geometric parameters, extra margin can be gained in improving the uniform elongation without comprising the loading capacity of a composite system. For a given volume fraction of reinforced core, an optimized reinforcement arrangement is found to achieve an improved ductility for a plate with sinusoidal corrugated core.