Response and failure of a double-shear beam subjected to mass impact

Experimental results are reported for the response and failure of a notched double-shear (DS) beam made from BS970/En24 medium carbon steel alloy when subjected to a mass impact loading. Mechanical properties and constitutive equations were obtained from quasi-static, dynamic and temperature tests on the beam material. Response and failure features were recorded for impact velocities between 30 and 110 ms^-1. A failure mode transition was observed between a ductile tensile rupture failure and an adiabatic shear banding failure. This test method could be used for studying shear stress-strain relations over a broad range of strain rates and for investigating different failure modes and their transitions. Finite-element numerical simulations were conducted for the response and failure in the notch section of the DS beam. Calibration factors were obtained, which may be used to calculate the actual stress and strain at the mid-point of a notch section in terms of the nominal values. Isothermal and adiabatic conditions obtained from a dimensional analysis were examined with the aid of FE simulations. An analytical model is used to predict the central block motions of DS beams and gives good agreement with experimental results. Various ductile fracture failure criteria were examined, among which the generalised plastic work density failure criterion leads to successful predictions for the ductile tensile failure within the notch section.