Simulation of high velocity armor fragmentation and human tissue response

The future of personal composite body armor to protect against impacts will inevitably be lighter, stronger, and more flexible to increase comfort for the user. Simulating the performance of the flexible materials requires modeling in finite element analysis using more advanced bio-compatible, bio-inspired composite materials for both the armor and the human soft tissue. These next generation of materials are highly hyper-viscoelastic with extreme hardening under high rate loading which is a current limitation for many numerical simulations. These limitations are addressed starting at the initial assumptions for continuum mechanics and general non-linear assumptions made for the viscoelastic materials. Applying the current built-in finite element code, an Hydrogel is tested via low velocity impacts in both experimental tests and numerical analysis. The results show that there is discrepancy between the two dynamic impact behaviors, whereby the force response of the real test is significantly longer in duration and with slower rise time compared to the numerical results. It is expected that in more extreme impact conditions that will be explored, these differences will diverge more dramatically and invalidate the finite element predictions. This shortcoming can only be prevented by introducing more strong non-linearity in the fundamental material properties and conditions in the impact model approximation.