Pulse shaper design for dynamic testing of viscoelastic materials using polymeric SHPB

• A method of pulse shaper design to test soft viscoelastic material using polymeric SHPB setup is proposed.
• Bilinear incident waveform at bar–specimen interface is found as a suitable choice for thin viscoelastic specimen.
• Wave dispersion and attenuation in polymeric bars must be considered during design.
• Effect of geometric parameters of pulse shaper on the incident waveform is discussed.

Pulse shapers are commonly used in SHPB (Split Hopkinson Pressure Bar) to extend the initial rise time and the duration of the incident pulse to achieve an early uniformity of the internal stress and a constant strain rate loading within the specimen. In this study, a method for optimal design of a pulse shaper for polymeric SHPB system in testing soft materials is proposed based on wave propagation analysis. Firstly, an inverse parametric identification technology is used to obtain the constitutive parameters of PMMA and the RTV630 silicone rubber to be tested, respectively. Then, the optimal incident waveform for testing viscoelastic specimen is determined. Finally, taking the WSXJ-208 silicone rubber under impact using polymeric SHPB as an example, by comparing the incident wave gotten from the numerical simulation and the optimal incident waveform considering the dispersion and attenuation effects of wave propagating in polymeric bars, an optimal shaper geometry is obtained, and showing an obvious modification in the waveform so as to get more accurate and reliable results.