Verification and validation of the Optimal Transportation Meshfree (OTM) simulation of terminal ballistics

We evaluate the performance of the Optimal Transportation Meshfree (OTM) method of Li et al. [21], suitably extended to account for seizing contact and fracture, in applications involving terminal ballistics. The evaluation takes the form of a conventional Verification and Validation (V&V) analysis. In support of the validation analysis, we have conducted tests concerned with the normal impact of Aluminum alloy 6061-T6 thin plates by S2 tool steel spherical projectile over a range of plate thicknesses of [0.8 mm, 1.6 mm] and a range of impact velocities of [100, 400]m/s. The tests were conducted at Caltech’s GALCIT gas-gun Plate-Impact Facility. We find excellent agreement between measured and computed perforation areas and a ballistic limits over the thickness and velocity ranges considered. Our verification analysis consists of model-on-model comparisons and an assessment of the convergence of the OTM method. Specifically, we find excellent agreement between the incident vs. residual velocities predicted by the OTM method and by the power-law relation of Recht and Ipson [36]. We also find robust linear convergence of the OTM method as measured in terms of residual velocity error vs. number of nodes.