Development of Multi-Scale Modeling Software for Entangled Soft Matter in Advanced Soldier Protection

摘要

The Department of Defense seeks to develop body armor that is, among other things, lighter and more flexible. For example, the new armor based on shear thickening fluids (STF) is very flexible, but stiffens under the load of impacting projectiles in order to provide protection. Hence, the interaction of the armor with human tissue (e.g., muscle) becomes very important. However, there is not sufficient understanding in how tissue responds to the large stresses, and high strain rates that occur in such interactions. Moreover, in order to test armor candidates, one needs a synthetic material that can mimic the response of tissue. Our projects seek to address both of these limitations, both by modeling the transient mechanical (rheological) properties of tissue, and by developing software that can predict the same response of many possible synthetic testing materials. Specifically, we proposed the following: 1. Generalization of our entanglement theory to cross-linked systems. 2. A progressive coarse graining of the theory to create a continuum-level description. Success here would create a model more amenable to simulation in complex geometries. This was a longer-term goal, with no promised deliverables in the time frame of the proposal. 3. Make available to the Army resulting computer code. 4. Generalization to co-polymers. 5. Generalization to semi- flexible polymers. Such polymers are ubiquitous in tissue, and largely determine their rheological and mechanical properties.