M-shaped specimen for the high strain rate tensile testing using a Split Hopkinson bar apparatus

International audienceAn experimental technique is proposed to determine the tensile stress-strain curve and strain to fracture of metals at high strain rates. An M-shaped specimen is designed which converts a compression loading at its boundaries into tensile loading of its gage section. The specimen can be used in a conventional split Hopkinson pressure bar apparatus, thereby circumventing experimental problems related to the gripping of tensile specimens under dynamic loading. The M-specimen achieves plane strain conditions within its gage section. This feature retards necking and allows for very short gage sections. This new technique has been validated both experimentally and numerically for true equivalent plastic strain rates of up to 4250/s