Dynamic Characterization of Porcine Lung Tissue*

In this study, the dynamic shear and uniaxial compressive response of porcine lung tissue was examined using modified Kolsky bar techniques. High rate compression data was collected using a hollow transmission bar to amplify weak material response. Radial deformation of annular specimens was captured by a modified Kolsky bar and high speed camera. The images depicted inhomogeneous specimen deformation induced by radial inertia effects, which compromised the validity of such high rate compression test techniques. A novel torsion technique was developed to obtain dynamic pure shear behavior of lung tissue. The equivalent stress-strain behavior of lung tissue obtained from both methods was compared and the pure shear response was found to be an order of magnitude lower than the uniaxial compressive response. These results indicate the previously established annular specimen technique for the Kolsky bar soft materials characterization, targeted on reducing the influence of inertia stress, may still have underestimated the effects of radial inertia and the associated inhomogeneous deformation in materials as soft as lung tissues.