Dynamic compressive response of porcine muscle measured using a split Hopkinson bar system with a pair of PVDF force transducers

Abstract

The classic metallic Split Hopkinson Pressure Bar (SHPB) cannot capture the transmitted signal accurately when measuring soft biological tissue, because of the very low wave impedance and strength of this material. So the dynamic compressive response of porcine muscle has been investigated by using a modified SHPB. The forces on both ends of the sample measured using Polyvinylidene fluor (PVDF) transducers were applied to calculate the stress in the specimen instead of the strain gauge signal on the transmitted bar. Moreover, a circular cardboard disk pulse shaper was applied for generating a suitable incident pulse to achieve stress equilibrium and constant strain rates in the specimens. Then, the dynamic mechanical properties of porcine muscle parallel and perpendicular to the fiber directions were measured, and the stress equilibrium process during loading was analyzed, as well as the inertia-induced extra stress being corrected. Furthermore, quasi-static tests were conducted at two different strain rates to investigate the strain rate dependence using a universal material testing machine. The results show that the stress-strain curves are sensitive to strain rate in the two different loading directions. The compressive stress perpendicular to the fiber direction is stiffer than that parallel to the fiber direction. In addition, a strain rate-dependent constitutive model was developed based on the mechanical response of the muscle at different strain rates and fitted to the experimental data. The results show that the overall fit is good, and the constitutive model could describe the muscle's dynamic mechanical properties.

Keywords

• PVDF
• Hopkinson bar
• Porcine muscle
• Dynamic mechanical properties
• Constitutive model