Southwest Research Institute has been performing conventional (2 km/s) and hypervelocity (~5.5 km/s) laboratory impact tests on a range of materials (pumice, concrete, sandstone, plaster, pure iron, aluminum 2024, granite, basalt aggregates in relation to the DART mission, etc.) to better understand the “momentum enhancement” effect. When an object like an asteroid or a target is impacted, some of the ejecta from the impact fly in the opposite direction of the projectile, leaving the target with more momentum than the initial momentum of the projectile. This additional momentum, or “momentum enhancement” could be important for the deflection of an asteroid in a space mission designed to change the asteroid’s trajectory.
Computer simulations of ejecta and momentum enhancement have proven to be very difficult for multiple codes (Eulerian, Lagrangian, SPH, etc.) One possible reason could be the lack of the proper physics for material strength or failure, for example a size effect on strength and failure or other physics. But the deficiency might instead be an intrinsic limitation of the codes possibly due to excessive element distortion, particle conversion algorithms, or stickiness of Eulerian codes.
This talk will summarize the experimental and numerical efforts from SwRI and other institutions trying to speculate on reasons for the inaccuracy of the codes and material models being used. Possible solutions will be discussed as well.