Comprehensive Characterization of Soft Tissue and Surrogate Materials across Varied Loading Methods

Exploring the mechanical properties of soft tissues under compressive loading is crucial for understanding their role in automobile incidents. Soft tissues, which serve as cushions or padding between bone and vehicle interiors, significantly influence contact duration and forces, thereby altering incident kinematics and injury. In this investigation, muscle and soft connective tissues from post-mortem human subjects (PMHS) forearms were excised and subjected to compression and indentation testing methods at various rates and strains. Specific samples with higher proportions of muscle were compared against samples without muscle tissues to evaluate the role of compositional changes. Anthropomorphic test device (ATD) upper extremity foam and vinyl–foam composite analog tissues underwent similar testing for comparison. High impact rates simulating those in high-speed automotive collisions were achieved using a custom-built drop tower impactor setup. The results revealed significantly higher stiffness values for samples with large proportions of muscle tissue compared to no muscle samples at smaller deformations. Substantial differences in stiffness were seen between soft tissues and ATD materials across most loading rates and strains, although some exceptions were noted at higher rates and strains. An indentation and modified Zener model were used to quantify material parameters. These findings provide a solid basis for advancing ATD analogs and have broader implications for soft tissue research. Moreover, this work represents a crucial step toward enhancing safety standards in the automotive industry.