Design of Dynamic Tensile Experiment for Polyurethane

The low wave velocity of stress waves in viscoelastic polymer materials makes it difficult for viscoelastic materials to maintain dynamic equilibrium in dynamic loading experiments. There is a scarcity of research findings on dynamic experiments of viscoelastic materials, particularly in the realm of dynamic tensile tests. To investigate the dynamic tensile mechanical behavior of viscoelastic materials, polyurethane (PU) was chosen as the subject of study. Electronic universal testing machines were used to conduct quasi-static tensile experiments at strain rates of 0.001\(\:{s}^{-1}\), 0.005\(\:{s}^{-1}\), and 0.025\(\:{s}^{-1}\), verifying the tensile mechanical behavior of viscoelastic PU under quasi-static experimental conditions. Using the split Hopkinson tensile bar (SHTB) as the dynamic loading apparatus, we simulated and verified the propagation patterns of dynamic tensile waves under various experimental scenarios. The most suitable connection scheme was then selected for experimental validation. Based on the macro and micro experimental analysis results obtained under the incident tensile wave, we determined the dynamic tensile experimental scheme for viscoelastic materials that fulfills the stress equilibrium condition. Additionally, we obtained the design results for the incident wave shape and the dimensions of the dynamic tensile samples.