Predicting ductile fracture during torsion testing using dislocation density tensor

Abstract

A model based on dislocation density tensor is proposed for predicting ductile fracture during torsion testing. The effect of prestrain induced by bar drawing on fracture strain is examined. First, an improved simple torsion testing machine, which is incorporated into a universal testing machine, is manufactured. Next, fracture strain calculated using the dislocation density tensor-based model agrees with experimental values, whereas fracture strain calculated using a previously proposed ellipsoidal void model does not agree with experimental values. Finally, fracture strain calculated using a previously proposed practical model based on prestrain consideration ratio agrees with experimental values.