A split Hopkinson pressure bar (SHPB) technique has been developed to study dynamic behavior of materials having low characteristic impedance. To enable better matching of characteristic impedance with a specimen, polymethyl methacrylate (PMMA) bars are used as the input and output bars. The viscoelastic properties of PMMA are determined in advance through preliminary experiments. In the present SHPB method, the wave analysis of the stress pulses is executed in the frequency domain. Incident, reflected and transmitted pulses on the PMMA input and output bars resulting from a SHPB test are resolved into frequency components by the Fourier transform, and are corrected to be the waveforms at the specimen-bar interfaces. The dynamic properties of the specimen are subsequently determined based on the corrected waveforms. We apply the proposed SHPB technique to several low impedance materials. Some structural adhesives as well as golf ball materials are tested with a view to examining their dynamic viscoelastic properties. The complex compliance for each material is determined as one of the dynamic properties in frequency domain. Furthermore, by employing the FEM simulation on collision tests of a golf ball, it is found that the proposed SHPB method provides reasonable estimations on the dynamic behavior of materials having low impedance.
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