Unified Tensile Fracture Criterion

Abstract

We find that the classical failure criteria, i.e., maximum normal stress criterion, Tresca criterion, Mohr-Coulomb criterion, and von Mises criterion, cannot satisfactorily explain the tensile fracture behavior of the bulk metallic glass (BMG) materials. For a better description, we propose an ellipse criterion as a new failure criterion to unify the four classical criteria above and apply it to exemplarily describe the tensile fracture behavior of BMGs as well as a variety of other materials. It is suggested that each of the classical failure criteria can be unified by the present ellipse criterion depending on the difference of the ratio alpha=tau(0)/sigma(0).

Cryogenic-temperature-induced transition from shear to dilatational failure in metallic glasses

“…However, below the transition point (20 K), the value of a becomes significantly large. The critical transition value of a at 20 K is close to the suggested value ( ffiffiffiffiffiffiffi ffi 1=2 p ) that separates the shear-dominated failure from the tensile failure in metallic glasses [29,39].…”

“…1b presents the macroscopic failure modes at different temperatures. It can be seen that, at temperatures of 300, 221, 152 and 77 K, the fracture angles are about 56°, 59°, 60°and 61°, respectively, falling in the common range for metallic glasses under uniaxial tensions [29,38,39]. This means that the failure in these cases is dominated by shear stress, but is also affected by normal stress.…”

“…7b). In fact, so long as r 0 6 ffiffiffiffiffiffi ffi 2s 0 p , dilatation-dominated tensile failure will occur [29,39]. That means that the real critical temperature will be slightly higher than 20 K. Once the STZ behaves in a dilatation-dominated fashion [14], the softening (or weakening) process will govern the strength of the material, corresponding to the decrease in macroscopic failure strength observed at T < 20 K (Fig.…”

Shear transformation zone volume determining ductile–brittle transition of bulk metallic glasses

“…8c) and the 653 K 48 h annealed sample (with free volume completely annealed out) tested at room temperature (Fig. 8d), they both failed in a brittle tensile fracture mode with fracture angles $90°, clearly indicating a cleavage cracking [35]. Thus we can conclude that either the structural annealing or the temperature decrease can reduce the propensity for the formation of multiple shear bands and hence degrade plastic deformation ability, and even induce a significant DBT in BMGs.…”

Deformation and failure of bulk metallic glasses under different initial temperatures

“…Comparatively, for the homogeneous flow of BMGs at high temperature (T ≥ T g ), the related analyses usually follow the models used for the crystalline alloys [1,3]. Regarding the yielding and failure of BMGs, a Corresponding author: chenxiaoweintu@yahoo.com some macroscopic failure criteria have been suggested and successfully describe the deviation of fracture surface from the maximum shear stress plane [12,13]. However, the micro-mechanism of deformation and failure of BMGs is still under the exploration process [14][15][16][17].…”