Ballistic impact response of elastomer-retrofitted corrugated core sandwich panels

Abstract

The ballistic impact resistance of metallic corrugated sandwich panels retrofitted with elastomeric coating (polyurea) is investigated through combined experimental and numerical efforts. Dynamic penetration process, failure mechanisms, ballistic limit velocity, and perforation energy threshold of polyurea-coated sandwich panels are firstly elucidated via experiments and then compared with those of non-coated sandwich panels. Subsequently, based upon a user-defined compressible model of polyurea, three-dimensional finite element (FE) simulations of both non-coated and coated sandwich panels are carried out to analyze the ballistic impact response, interrogate the energy absorption mechanisms, and assess the influence of coating position/thickness and projectile rigidity on ballistic performance. Excellent agreement between experimental measurements and numerical predictions is achieved. It is demonstrated that the presence of a sufficiently thick (e.g., ∼15 mm) impact-side elastomeric coating helps to curtail the kinetic energy of flat-ended projectiles, thus enhancing the penetration resistance considerably. The use of a thicker and impact-side coating is favored owing to its superior energy absorption capability. It is also ascertained that the effectiveness of polyurea coating in resisting rigid, flat-ended projectiles is much more remarkable relative to deformable, conical ones. Further, retrofitting an all-metallic sandwich panel with elastomeric coating broadens its multifunctionality significantly, enabling it to simultaneously carry structural loads, mitigate impact and blast loadings, and resist projectile penetration, at a minimal increase in fabrication cost and structural mass. The insights of this study provide a potential new avenue for enhancing the ballistic impact resistance as well as multifunctional attributes of all-metallic sandwich construction.