Determination of inelastic heat fraction of OFHC copper through dynamic compression

An approach to determine the inelastic heat fraction (IHF) value of metal by high-speed compression is established by combining dynamic deformation, infrared (IR) photography and finite element simulation. OFHC copper specimens are dynamically compressed and infrared thermographs captured at a rate of 1000 images/s. FEM simulation of the deformation is undertaken and the initial IHF value input adjusted until the computed average surface temperature matches the experimental data. It is found that for the IHF value identified, the predicted surface temperature distribution also exhibits good correlation with experimental results. For final strains in the range of 44–60%, a consistent IHF value of 0.68 is obtained. Using this value, the surface temperature of a sample deformed to a different final strain and at a different strain rate is predicted by FEM simulation and the numerical results show good agreement with test data in terms of average surface temperature and surface temperature distribution. The temperature field for the entire specimen is also predicted. Results indicate that high-speed compression at a strain rate of 1000/s to a final engineering strain of 70% may result in initiation of dynamic recovery in OFHC copper.