The issue of orbital debris has emerged as one of the most pressing challenges in the field of space environment protection today. Most contemporary spacecraft shielding architectures employ the Whipple bumper configuration, in which a thin sacrificial “bumper” layer intercepts incoming micrometeoroids or orbital debris, causing them to fragment before impacting the primary structure. To date, aluminum alloys have been the material of choice for the bumper layer, owing to their favorable strength-to-weight ratio and ease of fabrication. In the present study, however, we explore the potential advantages afforded by high-entropy alloys (HEAs) as Whipple bumper materials under hypervelocity impact conditions. Using the AUTODYN software platform and the Smooth Particle Hydrodynamics (SPH) method, we conducted a series of numerical simulations in which spherical projectiles traveling at hypervelocities collide with Whipple-like multilayer configurations. Two different bumper materials were considered: a conventional aluminum alloy and a novel, equiatomic high-entropy alloy designed for high strength and damage tolerance. For each target configuration, we varied the projectile diameter, impact velocity, and the ratio of bumper thickness to projectile diameter (t/D) in order to assess their influence on debris cloud characteristics. Our results reveal several statistically significant differences between the debris clouds generated by the two bumper materials under otherwise identical conditions. First, the total mass of fragments produced by the high-entropy alloy bumper is approximately 51.9% greater than that produced by the aluminum alloy bumper. Second, the number of low-mass debris particles (defined here as fragments below a specified mass threshold) increases by roughly 79.6% in the HEA case, while the count of high-mass fragments correspondingly decreases. Third, the maximum momentum in the Z-direction carried by the debris cloud—an important metric for assessing secondary impact risks—is reduced to less than 75% of the aluminum alloy value across all tested projectile diameters. A parametric analysis further indicates that the overall expansion rate of the debris cloud is predominantly governed by impact velocity: higher velocities produce more rapid radial dispersion, regardless of the t/D ratio. By contrast, the generation of “dangerous” fragments—those with relatively high mass or kinetic energy—is primarily influenced by the bumper’s t/D ratio: increasing the relative thickness yields fragments that, on average, have greater mass and energy. Taken together, these findings suggest that high-entropy alloy laminates could offer an advantageous trade-off between fragment size distribution and momentum transfer in Whipple-style hypervelocity shielding, potentially mitigating the risks posed by secondary debris impacts on spacecraft subsystems. Further experimental validation and optimization of HEA compositions are recommended to refine these conclusions and facilitate technology maturation for spaceflight applications.
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