There is a major knowledge gap limiting the effectiveness of human digital twins for use in armor design and testing. In order to accurately build a digital twin of the Warfighter requires in depth understanding of how soft biological tissues respond to a variety of loading conditions. Due to the viscous nature of soft biological tissue, the rate of loading has a large effect on the material properties. This means material properties of tissue measured under quasi-static conditions will be not be applicable in fast dynamic conditions. The material properties for different degrees and types of dynamic conditions may also affect material properties and, as such, a single dynamic loading condition may not be fully covered by a single constitutive relationship. While material properties have been measured for many soft tissues, most of the data is for static, quasi-static, or low strain rate loadings. There is a lack of data for higher strain-rate loading, the exact loading conditions needed to simulate the blast and impact injuries that PPE is designed to protect against. To achieve the goal of a digital twin of the Warfighter addressing PPE performance, we need to determine how viscous biological tissues respond to higher strain-rate loading.

The goal of this effort is to develop the techniques necessary to determine and quantify, both experimentally and computationally, how biological tissues behave under high strain-rate loading conditions such as blast and impact.