A constitutive model for a uranium-niobium alloy

Zubelewicz, Aleksander; Addessio, F. L.; Cady, Carl M.

doi:10.1063/1.2208907

Cited by 18 publications

(13 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The power-law viscoplasticity was first introduced in [58,59]. Strength σ p y = σ 0 A T (T) is determined at 0.2% strain, where σ 0 is athermal strength.…”

Section: Kinematics-based Construction Of Hall-petch Relationmentioning

confidence: 99%

Mechanisms-Based Transitional Viscoplasticity

Zubelewicz

2020

Crystals

View full text Add to dashboard Cite

When metal is subjected to extreme strain rates, the conversation of energy to plastic power, the subsequent heat production and the growth of damages may lag behind the rate of loading. The imbalance alters deformation pathways and activates micro-dynamic excitations. The excitations immobilize dislocation, are responsible for the stress upturn and magnify plasticity-induced heating. The main conclusion of this study is that dynamic strengthening, plasticity-induced heating, grain size strengthening and the processes of microstructural relaxation are inseparable phenomena. Here, the phenomena are discussed in semi-independent sections, and then, are assembled into a unified constitutive model. The model is first tested under simple loading conditions and, later, is validated in a numerical analysis of the plate impact problem, where a copper flyer strikes a copper target with a velocity of 308 m/s. It should be stated that the simulations are performed with the use of the deformable discrete element method, which is designed for monitoring translations and rotations of deformable particles. relevant material information, such as sensitivities to strain rate, temperature, size effect, etc. In a typical scenario, the models adapt the strain rate-insensitive solving scheme, where radial return seems to be the favorite procedure. In consequence, plastic strain is merely a byproduct of the requirement that stress must adhere to the yield surface. An interesting technique suitable for generating random dislocation arrangements is proposed by Gurrutxanga-Lerma [23]. The main concern of the study is focused on how a given population of dislocation structures influences the dominant features of the stress field. The stochastic analysis provides justification for Taylor's equation and the Hall-Petch relation. The study, however, is not concerned with how the dislocation structures are formed in the first place. Another approach to crystal plasticity is proposed by Langer [24]. His thermodynamics dislocation theory (TDT) is based on the observation that dislocation experience complex chaotic motions and the motion is responsible for the field fluctuations. One should expect the frequency of the fluctuations to be many orders of magnitude lower in comparison with the frequency of thermal excitations. According to Langer, the non-deterministic nature of dislocation dynamics makes the behaviors suitable for statistical and thermodynamics treatment. Brown [25] offered an interesting idea that plastic flow is responsible for the formation of dislocation structures in the state of self-organized criticality. In this interpretation, the dislocation structures evolve until reaching the state of maximum structural adaptiveness such that every site of the structure has a statistically equal chance to act as a nucleation site of further deformation. At the initial stages of plastic deformation, flow is initiated at points of weakness. However, as the process proceeds, the initiation sites become inactive and are replaced by newly cre...

show abstract

“…The power-law viscoplasticity was first introduced in [58,59]. Strength σ p y = σ 0 A T (T) is determined at 0.2% strain, where σ 0 is athermal strength.…”

Section: Kinematics-based Construction Of Hall-petch Relationmentioning

confidence: 99%

Mechanisms-Based Transitional Viscoplasticity

Zubelewicz

2020

Crystals

View full text Add to dashboard Cite

show abstract

“…In this construction, the model captures diffusional flow, power-law creep and plasticity. It is worth mentioning that similar power-law expressions have already been used for metals 23 24 and frictional materials 25 . Elastic material properties complete the constitutive description.…”

Section: Resultsmentioning

confidence: 99%

Mechanisms-based viscoplasticity: Theoretical approach and experimental validation for steel 304L

Zubelewicz

Oliferuk

2016

Sci Rep

View full text Add to dashboard Cite

We propose a mechanisms-based viscoplasticity approach for metals and alloys. First, we derive a stochastic model for thermally-activated motion of dislocations and, then, introduce power-law flow rules. The overall plastic deformation includes local plastic slip events taken with an appropriate weight assigned to each angle of the plane misorientation from the direction of maximum shear stress. As deformation progresses, the material experiences successive reorganizations of the slip systems. The microstructural evolution causes that a portion of energy expended on plastic deformation is dissipated and the rest is stored in the defect structures. We show that the reorganizations are stable in a homogeneously deformed material. The concept is tested for steel 304L, where we reproduce experimentally obtained stress-strain responses, we construct the Frost-Ashby deformation map and predict the rate of the energy storage. The storage is assessed in terms of synchronized measurements of temperature and displacement distributions on the specimen surface during tensile loading.

show abstract

“…However a careful analysis of the experimental results showed that the absence of the elastic precursor was not due to small differences in elastic and plastic wave velocities, hence the lack of a precursor was unexplained. Field et al (2001), Jackson (1976), Zubelewicz et al (2006) and Cady et al (2006) have studied U-6Nb extensively. U-6Nb twins and twinning dramatically reduces the overall shear stress.…”

Section: Introductionmentioning

confidence: 99%