Dynamic tensile constitutive equations and fracture of metallic neodymium and lanthanum

Based on tensile tests, static on MTS and dynamic on the first tensile loading in optimized tensile split Hopkinson bar (TSHB) tests for neodymium (Nd) and lanthanum (La) sheet specimens, this study determined tensile constitutive equations of Nd and La. It was found that the Nd and La sheet specimens were fractured during the first tensile loading in TSHB tests. The transmitted and reflected pulses of TSHB tests for Nd and La sheet specimens computed with the determined tensile constitutive equations and the strain rate dependent fracture strain criterion could be consistent with the experimental data. The relation between the dynamic failure strength and the strain rate was discussed. The fractured Nd and La sheets of tensile tests were investigated by using scanning electron microscope. It was found that a transition from random to deterministic damage evolution patterns was notable as the strain rates increase for La sheet specimens while the transition unobserved for Nd sheet specimens.