<p>Thermoplastic polymers, such as high-density polyethylene (HDPE), hold promise as intermediate layers in protective structures due to their potential to provide resistance to hypervelocity impact (HVI) damage while maintaining low weight and cost. Furthermore, the capability to accurately model the ultra-high strain rate behavior of polymers is crucial for advancing the design and optimization of protective systems. A prior investigation employed HVI experiments with a two-stage light gas gun to examine the response of HDPE under extreme conditions. Monolithic square targets, each 6.35 mm thick, were impacted by 10 mm diameter aluminum spheres at normal incidence with velocities ranging from 2.0 to 6.5 km/s. The study revealed that debris cloud tip velocity, perforation diameter, and target mass loss increased with impact velocity. High-speed imaging captured evidence of bulk melting and significant plastic deformation in the HDPE targets induced by the impacts. In this study, numerical simulations of the HVI experiments were conducted using the Elastic Plastic Impact Computation (EPIC) code, incorporating established material models and equations of state (EOS). Material properties and EPIC simulation parameters were calibrated to enhance agreement with experimental observations of HVI damage metrics, such as debris cloud geometry, tip velocity, and target damage morphology. The simulations demonstrated strong alignment with experimental results across most of the tested velocity range. Notably, the simulations predicted that the impact-induced heating of the targets elevated temperatures to the melting point of HDPE, consistent with experimental observations of bulk melting. The simulations also revealed that strain rates induced by the impacts reached magnitudes as high as <InlineEquation ID="IEq1"> <EquationSource Format="TEX">$10^6$</EquationSource> <EquationSource Format="MATHML"><math> <msup> <mn>10</mn> <mn>6</mn> </msup> </math></EquationSource> </InlineEquation> <InlineEquation ID="IEq2"> <EquationSource Format="TEX">$\hbox {s}^{-1}$</EquationSource> <EquationSource Format="MATHML"><math> <msup> <mtext>s</mtext> <mrow> <mo>-</mo> <mn>1</mn> </mrow> </msup> </math></EquationSource> </InlineEquation>. These findings provide critical insights into the extreme thermal and mechanical conditions experienced by HDPE during HVIs, highlighting the potential of simulation tools to aid in the design of impact-resistant polymer-based protective systems. </p>

EPIC Simulations of Hypervelocity Impacts of Aluminum Spheres into High-Density Polyethylene Plates

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发表日期：

2025年8月15日

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P. T. Mead,
J. A. Rogers,
T. N. Williams,
J. W. Wilkerson,
T. E. Lacy Jr.

摘要

Thermoplastic polymers, such as high-density polyethylene (HDPE), hold promise as intermediate layers in protective structures due to their potential to provide resistance to hypervelocity impact (HVI) damage while maintaining low weight and cost. Furthermore, the capability to accurately model the ultra-high strain rate behavior of polymers is crucial for advancing the design and optimization of protective systems. A prior investigation employed HVI experiments with a two-stage light gas gun to examine the response of HDPE under extreme conditions. Monolithic square targets, each 6.35 mm thick, were impacted by 10 mm diameter aluminum spheres at normal incidence with velocities ranging from 2.0 to 6.5 km/s. The study revealed that debris cloud tip velocity, perforation diameter, and target mass loss increased with impact velocity. High-speed imaging captured evidence of bulk melting and significant plastic deformation in the HDPE targets induced by the impacts. In this study, numerical simulations of the HVI experiments were conducted using the Elastic Plastic Impact Computation (EPIC) code, incorporating established material models and equations of state (EOS). Material properties and EPIC simulation parameters were calibrated to enhance agreement with experimental observations of HVI damage metrics, such as debris cloud geometry, tip velocity, and target damage morphology. The simulations demonstrated strong alignment with experimental results across most of the tested velocity range. Notably, the simulations predicted that the impact-induced heating of the targets elevated temperatures to the melting point of HDPE, consistent with experimental observations of bulk melting. The simulations also revealed that strain rates induced by the impacts reached magnitudes as high as $10^6$ $10^{6}$ $\hbox {s}^{-1}$ $s^{- 1}$ . These findings provide critical insights into the extreme thermal and mechanical conditions experienced by HDPE during HVIs, highlighting the potential of simulation tools to aid in the design of impact-resistant polymer-based protective systems.