A study on hypervelocity impact resistance of the Whipple shield with aluminum spherical micro-airbag metastructure using material point method

To enhance the hypervelocity impact protection performance of Whipple shields against high-speed space debris, an aluminum spherical micro-airbag array metastructure was designed without incorporating additional energy-absorbing materials such as porous materials or carbon fibers. This metastructure was fabricated using 3D printing technology. The protective performance of the Whipple shield was investigated and analyzed by constructing a numerical model of a spherical projectile with an initial velocity of 7.5 km/s impacting both the single-layer aluminum plate and the aluminum spherical micro-airbag metastructure. The finite element method is often inadequate for accurately calculating large plastic deformations and fracture damage problems, particularly when mesh distortions are involved. Therefore, the material point method (MPM) was employed in this study to simulate hypervelocity impact scenarios. After verifying the reliability of the MPM calculations through experiments, a three-dimensional numerical simulation of hypervelocity impacts on the Whipple shield was conducted. The mechanism of energy absorption and dissipation by the aluminum spherical micro-airbag metastructure was elucidated through a comparative analysis of the perforation size, debris cloud morphology, and key parameters such as velocity, momentum, energy, and temperature with those of a single-layer aluminum plate subjected to hypervelocity impact. The results indicate that the Whipple shield with the aluminum spherical micro-airbag metastructure reduces the axial kinetic energy of the projectile by 300 J more than the single-layer aluminum plate. In addition, the maximum expansion radius of the debris cloud is 32.2 mm larger than that of the single-layer aluminum plate. These findings demonstrate that the Whipple shield with the aluminum spherical micro-airbag metastructure significantly enhances protection against hypervelocity impacts from space debris. Moreover, when compared with relevant experimental data, the material point method simulation proves to be an effective computational tool for researching and developing new types of Whipple shields.