Mechanical behavior of titanium alloys in a dynamic punch test

In this paper, the deformation and fracture of Ti-5Al-2.5Sn alloy in complex stress states under biaxial tension at strain rates of up to several hundred per second are studied. Such loading conditions are provided during high-speed punch tests for thin plates. Samples of titanium alloy plates are punched with a hemispherical indenter, which is 20 mm in diameter, at velocities of 10, 5.0, 1.0, and 0.5 m/s with simultaneous recording of the punching forces and maximum deflection and video recording of the sample surface at a speed of 13.000 frames/s. Numerical simulation of punching tests is performed at punching velocities ranging from 0.5 to 10 m/s to validate the constitutive relationships and damage development kinetics. To describe the plastic flow and fracture of Ti-5Al-2.5Sn alloy in the range of strain rates from 0.001 to 1000 s$^{-1}$, the micromechanical damage model coupled with a model of the viscoplastic mechanical behavior of the material is used. The simulated crack shape and deflections are found to be similar to those obtained experimentally. Thus, dynamic bursting testing allows the validation of models of damage kinetics in complex stress states.