Abstract
The dynamic responses of honeycomb sandwich panels (HSPs) subjected to in-plane projectile impact were studied by means of explicit nonlinear finite element simulations using LS-DYNA. The HSPs consisted of two identical aluminum alloy face-sheets and an aluminum honeycomb core featuring three types of unit cell configurations (regular, rectangular-shaped, and reentrant hexagons). The ballistic resistances of HSPs with the three core configurations were first analyzed. It was found that the HSP with the reentrant auxetic honeycomb core has the best ballistic resistance, due to the negative Poisson's ratio effect of the core. Parametric studies were then carried out to clarify the influences of both macroscopic (face-sheet and core thicknesses, core relative density) and mesoscopic (unit cell angle and size) parameters on the ballistic responses of the auxetic HSPs. Numerical results show that the perforation resistant capabilities of the auxetic HSPs increase as the values of the macroscopic parameters increase. However, the mesoscopic parameters show nonmonotonic effects on the panels' ballistic capacities. The empirical equations for projectile residual velocities were formulated in terms of impact velocity and the structural parameters. It was also found that the blunter projectiles result in higher ballistic limits of the auxetic HSPs.
Highlights
As a new type of composite structure, lightweight sandwich panels with metallic honeycomb filler have been widely used as weight-efficient components, and are offering a wide range of potential applications in automotive, aerospace and military industries due to their great load-bearing capabilities in association with excellent energy dissipating performance
The sandwich panels consist of two identical aluminum alloy face-sheets and an aluminum alloy honeycomb core featuring three different unit cell configurations: regular (H-type), rectangular-shaped (R-type), and reentrant or auxetic (A-type) hexagons
Finite element (FE) models of these three types of honeycomb sandwich panels (HSPs) subjected to high-velocity hemispherical projectiles were developed and the impact processes were simulated by using the nonlinear finite element (FE) code LS-DYNA
Summary
As a new type of composite structure, lightweight sandwich panels with metallic honeycomb filler have been widely used as weight-efficient components, and are offering a wide range of potential applications in automotive, aerospace and military industries due to their great load-bearing capabilities in association with excellent energy dissipating performance. Ajdari et al [18] showed that decreasing the relative density in the direction of crushing enhances the energy absorption of honeycombs at early stages of crushing In contrast to these in-depth studies of honeycombs under in-plane distributed loads, whereas limited attention has been paid on the dynamic response of honeycombs or honeycomb sandwiches subjected to in-plane concentrated loads, especially high-velocity loads such as in the ballistic impact scenarios. Parametric studies are performed to evaluate the effects of several parameters, for example, impact velocity, honeycomb relative density, core and face-sheets thicknesses, and cell angle and size on the ballistic behavior of the HSPs. The primary outcome of this study is design information for such panels to be employed as armors against ballistic impact loads
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