Data processing of wave propagation in viscoelastic split Hopkinson pressure bar

In this study, the polymethyl methacrylate (PMMA) bar was taken as an example to study the data processing of the viscoelastic Split Hopkinson pressure bar (SHPB) during shock wave propagation. First, SHPB tests of the PMMA bar were conducted, and the strain data measured at the position of the strain gauges on the viscoelastic PMMA bar were processed by using the improved Lagrange analysis method (LAM) to obtain the full-field strain, particle velocity, and stress data. Then, the Zhu–Wang–Tang dynamic viscoelastic constitutive model was adopted, and the parameters were calibrated to determine the dynamic constitutive equation of the PMMA bar. By combining the characteristics method and the dynamic constitutive equation, numerical simulation was conducted to obtain the physical quantity data at each point on the PMMA bar, so as to realize the closed-loop test. By comparing the data obtained by the improved LAM with the data obtained by the characteristics method, it was found that the improved LAM can improve the calculation accuracy at the later loading stage and was more consistent with the actual situation, and the validity of data processing and the applicability of the dynamic constitutive equation at the early loading stage were verified as well. The improved LAM can be extended to the propagation calculation of the attenuation wave in SHPB tests of soft materials or low density materials.