A Continuum Model for Single Crystal Cyclic Plasticity

2003 ◽  
Vol 779 ◽  
Author(s):  
Biqiang Xu ◽  
Yanyao Jiang
Keyword(s):  
Single Crystal ◽  
Single Crystals ◽  
Kinematic Hardening ◽  
Strain Curve ◽  
Cyclic Behavior ◽  
Cyclic Plasticity ◽  
Amplitude Dependence ◽  
Slip Systems ◽  
Stress Strain ◽  
Copper Single Crystals

AbstractA constitutive model was developed to bridge the cyclic plasticity behavior of single crystals and the corresponding characteristic dislocation structures. Yield and flow were built on the individual slip systems. The Armstrong-Frederick kinematic hardening rule was invoked to capture the Bauschinger effect. A material memory parameter was introduced to consider the amplitude dependence of cyclic hardening. Latent hardening considering the interactions among the slip systems was used to describe the anisotropic cyclic behavior. The experimental results of copper single crystals were used to validate the model developed. It was found that the model was able to adequately describe the well-known three distinctive regions in the cyclic stress-strain curve of the FCC single crystal oriented for single slip and the associated dislocation substructures. The model was capable of capturing the enhanced hardening observed in copper single crystals in multi-slip orientations. For a given loading history, the model can predict not only the saturated stress-strain response but also the detailed evolution of the transient cyclic behavior. The characteristic dislocation structures can be featured with the slip evolution.

An Application of Incremental Plasticity Theory to Fatigue Life Prediction of Steels

1991 ◽  
Vol 113 (4) ◽  
pp. 404-410 ◽  
Author(s):  
W. R. Chen ◽  
L. M. Keer
Keyword(s):  
Fatigue Life ◽  
Life Prediction ◽  
Kinematic Hardening ◽  
Yield Condition ◽  
Strain Curve ◽  
Fatigue Life Prediction ◽  
304 Stainless Steel ◽  
Flow Rule ◽  
Stress Strain ◽  
Von Mises

An incremental plasticity model is proposed based on the von-Mises yield condition, associated flow rule, and nonlinear kinematic hardening rule. In the present model, fatigue life prediction requires only the uniaxial cycle stress-strain curve and the uniaxial fatigue test results on smooth specimens. Experimental data of 304 stainless steel and 1045 carbon steel were used to validate this analytical model. It is shown that a reasonable description of steady-state hysteresis stress-strain loops and prediction of fatigue lives under various combined axial-torsional loadings are given by this model

THE EFFECT OF ADDITION AGENTS ON CATHODE POLARIZATION DURING ELECTRODEPOSITION OF COPPER AT SINGLE CRYSTAL COPPER CATHODES

1955 ◽  
Vol 33 (12) ◽  
pp. 1756-1767
Author(s):  
K. Ekler ◽  
C. A. Winkler
Keyword(s):  
Steady State ◽  
Single Crystal ◽  
Single Crystals ◽  
Linear Relation ◽  
Crystal Orientation ◽  
Chloride Ion ◽  
Addition Agent ◽  
Cathode Polarization ◽  
Single Crystal Copper ◽  
Copper Single Crystals

The polarization–time relations for the initial (Pi), maximum (Pmax), and pseudo-steady-state (Ps) polarizations on copper single crystals in the absence and presence of gelatin and gelatin plus chloride ion were found to depend upon crystal orientation. The Pi and Pmax in the absence of gelatin, the Pi in its presence, and the static potentials were all similarly related to the reticular density. The Pi increased, and the time to maximum polarization (tmax) decreased, with increase of current density; the relations between these quantities showed marked differences for the different crystals. The variation with reticular density of Pi and Pmax in the absence of addition agents and of Pi in its presence probably represents differences in activation overpotential at the various crystal faces. The adsorption of gelatin on different crystal faces was also found to be markedly different. Polarization in the presence of gelatin was decreased by small amounts of chloride ion; a linear relation for all the crystals used was obtained by plotting the increase in polarization caused by gelatin against the decrease caused by 2 mgm./liter chloride ion in the presence of gelatin. In the absence of addition agent, change of acid concentration from 50 to 200 gm./liter had no effect on Pi and addition of chloride ion had no effect on Ps at single crystal cathodes.

SIZE EFFECT ON DEFORMATION MODE IN MICRON-SIZED Ti-5Al SINGLE CRYSTAL LOADED ALONG $[2\,\overline 1 \,\overline 1 \,0]$ AND [0001]

2010 ◽  
Vol 24 (15n16) ◽  
pp. 2466-2471 ◽  
Author(s):  
LIN XIAO ◽  
QIAN YU ◽  
QIAOYAN SUN ◽  
JUN SUN
Keyword(s):  
Single Crystal ◽  
Single Crystals ◽  
Deformation Mode ◽  
Slip Systems ◽  
Free Standing ◽  
Physical Size ◽  
Specimen Width ◽  
Starvation Effects ◽  
Micro Pillars ◽  
Starvation Effect

Free-standing sub-micron Ti -5 Al single crystal square pillars were fabricated along [Formula: see text] double slip and [0001] twinning orientations using FIB fabrication processes. Samples in range of 0.4 to 2.0µm were compressed. The yield stress increases much higher than their bulk counterpart as the specimen width decreases. The tendency of "smaller is stronger" is displayed in Ti -5 Al single crystals loaded along [Formula: see text] and [0001] orientations. The number of slip systems is restricted by specimen physical size as it declines from 2µm to 0.5µm, when the specimens were subjected to double slip loading. Meanwhile, when sample size is less than 1.0µm, micro-pillars along twinning orientation have to compensate the incomplete twinning deformation via shearing due to geometrical restriction and dislocation starvation effects. This variation of deformation mode could be attributed to the starvation effect of dislocations.

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