Determination of Viscoelastic Models for 2-Piece Golf Ball using Polymeric Split Hopkinson Pressure Bar

A split Hopkinson pressure bar (SHPB) technique has been developed to study the dynamic behavior of materials having low characteristic impedance. To obtain better matching with low impedance specimens, polymethyl methacrylate (PMMA) bars are used as the input and output bars. The viscoelastic properties of PMMA are determined in advance through preliminary wave propagation experiments. In the present SHPB method, the wave analysis of the stress pulses is conducted in the frequency domain. The incident, reflected and transmitted pulses on the PMMA input and output bars obtained from a SHPB test are resolved into frequency components using the Fourier transform, and corrected to obtain the waveforms at the specimen-bar interfaces. The dynamic viscoelastic properties of the specimen are subsequently determined based on the corrected waveforms. The proposed SHPB technique is then applied determined the viscoelastic models for core and cover materials of a 2-piecegolf ball. The complex compliance for each material is determined as one of the viscoelastic properties in the frequency domain. Furthermore, it is verified through the FEM simulations on the impact of golf balls that the proposed SHPB method provides reasonable estimates of the dynamic behavior of low impedance materials.