A viscoelastic split Hopkinson pressure bar technique and its applications to several materials

A new kind of split Hopkinson bar (SHB) technique is presented to study dynamic behavior of materials having low characteristic impedance, such as polymers or elastomers. To enable better matching of characteristic impedance with specimens, polymethyl methacrylate (PMMA) bars, which are considered to be viscoelastic bars, are used as the input and output bars. In The proposed SHB method, the wave analysis of the strain pulses is executed in the frequency domain. Strain histories of the input and output bars resulting from a SHB test are resolved into frequency components by Fourier transformation, and waveforms at measurement points are corrected to those at the interfaces between a specimen and bars. The proposed viscoelastic SHB technique is successfully applied to several low impedance materials. The complex compliance of each material is experimentally determined by evaluating strain-stress ratio in the frequency domain, and viscoelastic models are also identified based on variations of the complex compliances.