von Mises yield criterion

About: von Mises yield criterion is a research topic. Over the lifetime, 4374 publications have been published within this topic receiving 82642 citations. The topic is also known as: Von Mises stress.

Dynamic response of Cu 46 Zr 54 metallic glass to high-strain-rate shock loading: Plasticity, spall, and atomic-level structures

Abstract: We investigate dynamic response of ${\text{Cu}}_{46}{\text{Zr}}_{54}$ metallic glass under adiabatic planar shock wave loading (one-dimensional strain) with molecular dynamics simulations, including Hugoniot (shock) states, shock-induced plasticity, and spallation. The Hugoniot states are obtained up to 60 GPa along with the von Mises shear flow strengths, and the dynamic spall strengths, at different strain rates and temperatures. The spall strengths likely represent the limiting values achievable in experiments such as laser ablation. For the steady shock states, a clear elastic-plastic transition is identified (e.g., in the shock velocity-particle velocity curve), and the shear strength shows strain softening. However, the elastic-plastic transition across the shock front displays transient stress overshoot (hardening) above the Hugoniot elastic limit followed by a relatively sluggish relaxation to the steady shock state, and the plastic shock front steepens with increasing shock strength. The local von Mises shear strain analysis is used to characterize local deformation, and the Voronoi tessellation analysis, the corresponding local structures at various stages of shock, release, tension and spallation. The plasticity in this glass, manifested as localized shear transformation zones, is of local structure rather than thermal origin, and void nucleation occurs preferentially at the highly shear-deformed regions. The Voronoi and shear strain analyses show that the atoms with different local structures are of different shear resistances that lead to shear localization (e.g., the atoms indexed with $⟨0,0,12,0⟩$ are most shear-resistant, and those with $⟨0,2,8,1⟩$ are highly prone to shear flow). The dynamic changes in local structures are consistent with the observed deformation dynamics.

Influence of the Yield-to-Tensile Strength Ratio on the Failure Assessment of Corroded Pipelines

Abstract: It is well known that both the yield strength and the tensile strength of a material have significant effect on the failure behavior of pipelines. Thus it can be anticipated that the yield-to-tensile strength (Y/T) is closely related to the strain hardening behavior of the material, and it also influences the failure behavior. This paper theoretically explores the influence of T/Y (the inverse of Y/T) ratio on the failure pressure of pipelines with or without corrosion defects. Based on the instability of deformation and finite strain theory, a plastic collapse criterion for close-ended pipes without corrosion defects is developed first. The constitutive behavior of line pipes is characterized by a power-law strain hardening relation, while the plastic deformation obeys the Mises yield criterion and the associated deformation theory of plasticity. An approximate relationship between the T/Y ratio and the strain hardening exponent n is obtained, and a closed-form solution to the limit pressure of pipe based on T/Y is derived. This plastic instability model is extended to predict the failure pressure of pipelines with corrosion defects, and validated by the PCRI experimental database. The results show that (a) the T/Y ratio is simply proportional to the strain hardening exponent n, which is almost independent of the yield strain and affected by the definition of the yield stress; (b) the failure pressure predicted by the present plastic instability model increases as the T/Y ratio decreases; and (c) as T/Y → 1, the present solution approaches to that predicted by the Mises strength criterion based on the nominal hoop and axial stresses.Copyright © 2003 by ASME