Numerical and Experimental Studies of Compression-Tested Copper: Proposal for a New Friction Correction

New empirical relationship is proposed to calculate instantaneous maximum diameters on the sample during compression test. The proposal is a relationship between instantaneous maximum diameter, friction coefficient, initial dimensions of the sample and the displacement during the compression test. Seventeen compression tests were carried out to copper cylindrical samples without lubrication at room temperature to obtain this new empirical relationship. Numerical simulations were carried out taking into a count this new relationship for numerical validation. The maximum diameters calculated with this new empirical relationship are the same to the experimental measurements. The mechanical behavior calculated with this new relationship and with the friction corrections of Rowe and Dieter are similar. The simulations are similar to the experiments, with differences lower than 4.21%. The simulation shows higher hardening in the middle of the sample than on the bottom. Numerical simulations show that, possibly, the friction coefficient between sample and dies changes meanwhile the sample is hardening.