Some Investigations into Mechanical Behvaior of Soft Bilogical Tissues

Abstract

The human body is subjected not only to low strain-rates but also to high strain-rates in high speed impact scenarios such as automobile and aircraft crashes, sudden slip and falls, explosive blast and ballistic effects, industrial accidents, athletic sport events, gunshots and blunt impacts. The stress-strain data under high impact loading is necessary to develop constitutive models for computational simulations of automotive impact and blast scenarios. The mechanical behavior of soft tissues under high speed impact is also required to develop a biofidelic finite element human body models (HBMs) for better understanding of injury and injury mechanisms, and for developing efficient body armors. The study of mechanical behavior of soft tissues is therefore of significant interest under high dynamic loading condition. newlineIn the present study, an experimental methodology to investigate the dynamic stress-strain response of caprine muscle tissue at higher strain rates under both compressive and tensile loading has been described. Design and development of an integrated polymeric split Hopkinson pressure bar (PSHPB) setup for this purpose has been presented. An integrated PSHPB has been used under both compression and tension just by changing the specimen loading and striker bar loading attachment without changing the pressure bars, data acquisition system and data processing program. By using this setup, the stress-strain response of lower extremity muscle tissue along and transverse to the muscle fiber direction have been characterized in the strain rate range of (700 s-1-4200 s-1) and (500 s-1-3500 s-1) under both dynamic compressive and tensile loading respectively. The results showed that both compressive and tensile stress-strain responses of muscle tissue in both fiber directions are non-linear, strain-rate sensitive and tissue directional dependent. The strain-rate sensitivity in compressive tests is most dependent on the muscle fiber directions than in tensile tests. It is also observed that at the same strain r