Constitutive description of dynamic deformation: physically-based mechanisms
Reads0
Chats0
TLDR
In this article, the response of metals to high-strain-rate deformation is successfully described by physically-based mechanisms which incorporate dislocation dynamics, twinning, displacive (martensitic) phase transformations, grain-size, stacking fault, and solution hardening effects.Abstract:
The response of metals to high-strain-rate deformation is successfully described by physically-based mechanisms which incorporate dislocation dynamics, twinning, displacive (martensitic) phase transformations, grain-size, stacking fault, and solution hardening effects. Several constitutive equations for slip have emerged, the most notable being the Zerilli–Armstrong and MTS. They are based on Becker’s and Seeger’s concepts of dislocations overcoming obstacles through thermal activation. This approach is illustrated for tantalum and it is shown that this highly ductile metal can exhibit shear localization under low temperature and high-strain-rate deformation, as predicted from the Zerilli–Armstrong equation. A constitutive equation is also developed for deformation twinning. The temperature and strain-rate sensitivity for twinning are lower than for slip; on the other hand, its Hall–Petch slope is higher. Thus, the strain rate affects the dominating deformation mechanisms in a significant manner, which can be quantitatively described. Through this constitutive equation it is possible to define a twinning domain in the Weertman– Ashby plot; this is illustrated for titanium. A constitutive description developed earlier and incorporating the grain-size dependence of yield stress is summarized and its extension to the nanocrystalline range is implemented. Computational simulations enable the prediction of work hardening as a function of grain size; the response of polycrystals is successfully modeled for the 50 nm–100 m range. The results of shock compression experiments at pulse durations of 3–10 ns (this is two–three orders less than gas-gun experiments) are presented. They prove that the defect structure is generated at the shock front; the substructures observed are similar to the ones at much larger durations. A mechanism for dislocation generation is presented, providing a constitutive description of plastic deformation. The dislocation densities are calculated which are in agreement with observations. The threshold stress for deformation twinning in shock compression is calculated from the constitutive equations for slip, twinning, and the Swegle–Grady relationship. © 2002 Elsevier Science B.V. All rights reserved.read more
Citations
More filters
Journal ArticleDOI
Predicting twinning stress in fcc metals: Linking twin-energy pathways to twin nucleation
TL;DR: In this article, a hierarchical theory was proposed to predict critical twinning stress in face-centered cubic metals without any empiricism at any length scale, and the theory predicts a monotonic relation between the unstable twin stacking fault energy and twin nucleation stress revealing the physics of twinning.
Journal ArticleDOI
Deformation of FCC nanowires by twinning and slip
TL;DR: In this article, the authors present atomistic simulations of the tensile and compressive loading of single crystal face-centered cubic (FCC) nanowires with different stacking fault energies.
Journal ArticleDOI
Microstructural based models for bcc and fcc metals with temperature and strain rate dependency
George Z. Voyiadjis,Farid Abed +1 more
TL;DR: In this paper, the authors developed microstructural physical based constitutive models to characterize the deformation behavior of body centered cubic (bcc) and face centered cubic(fcc) metals under different strain rates and temperatures.
Journal ArticleDOI
A first-principles measure for the twinnability of FCC metals
Ellad B. Tadmor,Noam Bernstein +1 more
TL;DR: In this paper, a theoretical measure for twinnability in face-centered-cubic (fcc) metals is obtained through homogenization of a recently introduced criterion for deformation twinning (DT) at a crack tip in a single crystal.
Journal ArticleDOI
Shock deformation of face-centred-cubic metals on subnanosecond timescales
Eduardo M. Bringa,K. Rosolankova,Robert E. Rudd,B. A. Remington,Justin Wark,Mark A. Duchaineau,Daniel H. Kalantar,James Hawreliak,James Belak +8 more
TL;DR: Large-scale molecular dynamics simulations of shock-wave propagation through a metal allowing a detailed analysis of the dynamics of high strain-rate plasticity resolve the important discrepancy in the evolution of the strain from one- to three-dimensional compression observed in diffraction experiments.
References
More filters
Journal ArticleDOI
The deformation of plastically non-homogeneous materials
TL;DR: The geometrically necessary dislocations as discussed by the authors were introduced to distinguish them from the statistically storages in pure crystals during straining and are responsible for the normal 3-stage hardening.
Book
Dynamic Behavior of Materials
TL;DR: In this paper, the authors present a method to produce dynamic deformation at high strain rates by using Shear Bands (Thermoplastic Shear Instabilities) and dynamic fracture.
Book
Deformation-Mechanism Maps: The Plasticity and Creep of Metals and Ceramics
H.J. Frost,Michael F. Ashby +1 more
TL;DR: Deformation-mechanism maps: the plasticity and creep of metals and ceramics as discussed by the authors, Deformation-Mechanism Maps of metal deformation: the deformation and the creep of metal and ceramic.
Journal ArticleDOI
Towards the ultimate conservative difference scheme. IV. A new approach to numerical convection
TL;DR: In this paper, an approach to numerical convection is presented that exclusively yields upstream-centered schemes, which start from a meshwise approximation of the initial-value distribution by simple basic functions, e.g., Legendre polynomials.
Journal ArticleDOI
Dislocation-mechanics-based constitutive relations for material dynamics calculations
TL;DR: An improved description of copper and ironcylinder impact (Taylor) test results has been obtained through the use of dislocation-mechanics-based constitutive relations in the Lagrangian material dynamics computer program EPIC•2.