Numerical simulation of Yilan crater formation process

The formation process of the Yilan crater was numerically studied based on the iSALE-2D simulation code. The Euler algorithm was used to carry out the numerical simulation, and eight groups of working conditions were simulated. According to the scaling law, it was determined that the projectile diameter range was 90 to 120 m, and the projectile velocity was 12 and 15 km/s. Simulation results under the corresponding working conditions within 150 s of impact were obtained, including the crater diameter, depth, and crater profile curve. The optimal impact conditions of the Yilan crater were studied, and the formation and distribution of the molten layer during the cratering process were statistically analyzed. Combined with the point source cratering similarity law model, the relationship of cratering radius under the strength mechanism was obtained by fitting. The research results show that, according to the comparison between the simulated data and actual exploration data, a granite asteroid with a diameter of 120 m and an impact velocity of 12 km/s vertically hits the surface, forming a crater with a shape similar to the Yilan crater. The crater has a final diameter of 1 840 m and a crater edge depth of 263 m, which is in good agreement with the exploration data of the Yilan crater. Three stages of crater formation were reproduced: contact and compression, excavation, and modification. The distribution of the impact melting layer of the target plate material during the crater formation under the simulated conditions were revealed. The material melted completely when the peak pressure exceeds 56 GPa during the impact process, and this process was completed within 20 ms. Most melts was distributed at the bottom of the crater in layers and stacks, and a small amount of melts was deposited discretely on the surface of the target plate. The mass of the completely melted material is about 24 times the projectile mass. The relative error between the simulation results and the fitted crater radius relational results under the conditions with 120 m diameter and 12 km/s impact velocity is 10.3%. © 2023 Explosion and Shock Waves. All rights reserved.