Compression response of a thermoplastic elastomer gel tissue surrogate over a range of strain-rates

The mechanical response of a thermoplastic elastomer synthetic ballistic gel is studied over a range of strain-rates. Experiments were conducted at room temperature under uniaxial stress compression at rates ranging from 0.001 to 500/s. Low-rate experiments (<1/s) were conducted with a servo-hydraulic load frame. High-rate experiments (>100/s) were conducted with a polymeric Kolsky bar, along with several modifications to improve data quality. These modifications include the use of a commercial force transducer, a normal displacement interferometer, and a line laser extensometer. Because of the low shear strength and comparatively high compressibility of these materials, inertial effects are very pronounced. Specimen size is varied in an effort to study inertial effects at various loading rates. High speed photography is also used to demonstrate the presence of non-uniform deformation, due to both inertia and friction between the specimen and the loading surfaces. Finally, numerical simulation is used to verify trends observed in the experiments and further validate the data. It is concluded that this material is rate sensitive, with an almost three-fold increase in stiffness over the range of strain-rates studied.