Twinning Deformation in Martensite Microstructure

1999 ◽  
Vol 578 ◽  
Author(s):  
G.J. Ackland ◽  
U. Pinsook
Keyword(s):  
Molecular Dynamics ◽  
Shear Strain ◽  
Yield Stress ◽  
Stacking Faults ◽  
Strain Curve ◽  
Stress Strain Curve ◽  
Yield Strain ◽  
Twin Boundaries ◽  
Stick Slip ◽  
Martensite Microstructure

AbstractMolecular dynamics is used to study twinning deformation in a martensite microstructure obtained from rapid cooling β zirconium through the bcc-hcp transition. The microstructure is composed of (1011) twin boundaries and boundary dislocations which sometimes spread across the twins to form stacking faults. A series of such equilibrium microstructures subjected to discrete, increasing < 1012 > (1011) shear strain. The stress-strain curve has stick-slip behaviour with yield stress of ≈ 5.OKbar and yield strain of ≈ 3.8%. Deformation occurs through movement of twin boundaries in segments between boundary dislocations. Straight perfect twin boundaries do not move.

Molecular dynamics simulations of the effect of temperature and strain rate on the plastic deformation of body centred cubic iron nanowires

2021 ◽  
pp. 1-19
Author(s):  
Qian Wu ◽  
Yong Wang ◽  
Tao Han ◽  
Hongtao Wang ◽  
Laihui Han ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Plastic Deformation ◽  
Strain Rate ◽  
Yield Stress ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Strain Curve ◽  
Dislocation Slip ◽  
Stress Strain Curve ◽  
Stress Strain

Abstract The tensile tests of BCC Fe nanowires were simulated through molecular dynamics methods. The temperature and strain rate effects on the mechanical properties as well as the orientation-dependent plastic deformation mechanism were analyzed. For [001]-oriented BCC Fe nanowires, as the temperature increased, the yield stress and Young's modulus decreased. While the yield stress and Young's modulus increased as the strain rate increased. With the increase of temperature, when the temperature was less than 400 K, the twin propagation stress decreased dramatically, and then tended to reach a saturation value at higher temperatures. Under different temperatures and strain rates, the [001]-oriented Fe nanowires all deformed by twinning. The oscillation stage in the stress-strain curve corresponds to the process from the nucleation of the twin to the reorientation of the nanowire. For [110]-oriented Fe nanowires, the plastic deformation is dominated by dislocation slip. The independent events such as the nucleation, slip, and annihilation of dislocations are the causes of the unsteady fluctuations in the stress-strain curve. The Fe nanowires eventually undergo shear damage along the dominant slip surface.

Stress-Strain Curves for Oxygen-Free High Conductivity Copper at Shear Strain Rates of up to 103s-1

1970 ◽  
Vol 185 (1) ◽  
pp. 1149-1158 ◽  
Author(s):  
K. Bitans ◽  
P. W. Whitton
Keyword(s):  
Shear Strain ◽  
Testing Machine ◽  
Shear Bands ◽  
Strain Curve ◽  
Strain Rates ◽  
Adiabatic Shear Bands ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
The Given ◽  
Tubular Specimens

Shear stress-shear strain curves for o.f.h.c. copper at room temperature have been obtained at constant shear strain rates in the range 1 to 103s-1, using thin walled tubular specimens in a flywheel type torsion testing machine. Results show that, for a given value of strain, the stress decreases when the rate of strain is increased. Moreover, the elastic portion of the stress-strain curve tends to disappear as the rate of strain is increased. It is postulated that these effects are due to the formation of adiabatic shear bands in the material when the given rate of strain is impressed rapidly enough. A special feature of the design of the testing machine used is the rapid application of the chosen strain rate.

Effect of Circular Hole Notch Size on Strength Characteristics of CFRP/AL7075 Hybrid Composites

2003 ◽  
Vol 17 (08n09) ◽  
pp. 1788-1794
Author(s):  
Han Ki Yoon ◽  
Joon Soo Park ◽  
Sang Pill Lee ◽  
Yi Hyun Park ◽  
Yu Sik Kong ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Hybrid Composites ◽  
Strain Curve ◽  
Strength Analysis ◽  
Analytical Prediction ◽  
Stress Strain Curve ◽  
Yield Strain ◽  
Notched Strength ◽  
Element Method

As for the properties on both the aluminum and the CFRP which are used to make CFRP/AL7075 hybrid composites, CARALL (carbon reinforced aluminum laminate). In the CARALL specimen for rule of mixture, we were analyzed notched strength by finite element method. The results obtained from FEM notched strength analysis and experimental are as follows; In the unnotch CARALL specimen, the stresses imposed CFRP, epoxy, A17075 obtained by finite element method strength solution for A/C9991, when strain 0.48%, are 392 Mpa, 26 Mpa and 321 Mpa, respectively. The slope of the stress-strain curve by FEM increase in keeping with the hole size and the yield strain decrease to 36% and 55% for A/C9993 and A/C9991 respectively. And an agreement is found between the experimental results and the FEM analytical prediction results.

Effect of void size and Mg contents on plastic deformation behaviors of Al-Mg alloy with pre-existing void: Molecular dynamics study

2022 ◽  
Author(s):  
Ning Wei ◽  
Ai-Qiang Shi ◽  
Zhi-Hui Li ◽  
Bing-Xian Ou ◽  
Si-Han Zhao ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Plastic Deformation ◽  
Yield Stress ◽  
Stacking Faults ◽  
Mg Alloy ◽  
Void Size ◽  
Plastic Mechanism ◽  
Deformation Properties ◽  
Eam Potential ◽  
Mg Content

Abstract The plastic deformation properties of cylindrical pre-void Aluminum-Magnesium (Al-Mg) alloy under uniaxial tension are explored using molecular dynamics simulations with embedded atom method (EAM) potential. The factors of Mg content, void size, and temperature are considered. The results show that the void fraction decreases with increasing Mg in the plastic deformation, and it is almost independent of Mg content when Mg is beyond 5%. Both Mg contents and stacking faults around the void affect the void growth. These phenomena are explained by the dislocation density of the sample and stacking faults distribution around the void. The variation trends of yield stress caused by void size are in good agreement with Lubarda model. Moreover, temperature effects are explored, the yield stress and Young's modulus obviously decrease with temperature. Our results may enrich and facilitate the understanding of the plastic mechanism of Al-Mg with defects or other alloys.

Computer Simulation of Tensile Deformation of Titanium Small Single Crystals with Stacking Faults

1993 ◽  
Vol 319 ◽  
Author(s):  
M. Aoshima ◽  
T. Kusube ◽  
J. Ida ◽  
Masao Doyama
Keyword(s):  
Molecular Dynamics ◽  
Computer Simulation ◽  
Single Crystals ◽  
Yield Stress ◽  
Tensile Deformation ◽  
Tensile Axis ◽  
Stacking Faults ◽  
Stacking Fault ◽  
Molecular Dynamics Method ◽  
Dynamics Method

AbstractSmall single crystals of titanium with and without stacking faults have been pulled by use of the molecular dynamics method. The tensile axis was [0001] and the stacking fault was introduced on (0001) pianes. The yield stress was higher in the crystal with stacking faults. The deformation was complicated in the crystal with stacking fault. Dislocations were created near the tip of a crack and moved on (1122).

Strain Distributions around Cracks in Ductile Sheets during Loading and Unloading

1965 ◽  
Vol 7 (3) ◽  
pp. 312-317 ◽  
Author(s):  
J. R. Dixon ◽  
J. S. Strannigan
Keyword(s):  
Shear Strain ◽  
Plane Stress ◽  
Surface Coating ◽  
Fatigue Cracks ◽  
Strain Curve ◽  
Elastic Plane ◽  
Sheet Metals ◽  
Stress Strain Curve ◽  
Maximum Shear Strain ◽  
Loading And Unloading

Strain distributions around fatigue cracks in different sheet metals have been obtained by using a photoelastic surface coating with a reflection polariscope. It is shown that an estimate of the distribution of the maximum shear strain, y, near the crack tip, during both loading and unloading of the sheet, requires a knowledge of only the stress-strain curve of the material and the theoretical elastic plane-stress solution.

Strain-Rate Effects on Constitutive Behavior of Sn3.8-Ag0.7-Cu Lead-Free Solder

2009 ◽  
Author(s):  
Kok Ee Tan ◽  
John H. L. Pang
Keyword(s):  
Strain Rate ◽  
Yield Stress ◽  
Strain Curve ◽  
Tensile Tests ◽  
Lead Free ◽  
Indentation Hardness ◽  
Strain Rates ◽  
Test Results ◽  
Stress Strain Curve ◽  
Stress Strain

In this paper, the strain-rate dependent mechanical properties and stress-strain curve behavior of Sn3.8Ag0.7Cu (SAC387) solder is presented for a range of strain-rates at room temperature. The apparent elastic modulus, yield stress properties and stress-strain curve equation of the solder material is needed to facilitate finite element modeling work. Tensile tests on dog-bone shaped bulk solder specimens were conducted using a non-contact video extensometer system. Constant strain-rate uni-axial tensile tests were conducted over the strain-rates of 0.001, 0.01, 0.1 and 1 (s−1) at 25°C. The effects of strain-rate on the stress-strain behavior for lead-free Sn3.8Ag0.7Cu solder are presented. The tensile yield stress results were compared to equivalent yield stress values derived from nano-indentation hardness test results. Constitutive models based on the Ramberg-Osgood model and the Cowper-Symond model were fitted for the tensile test results to describe the elastic-plastic behavior of solder deformation behavior.

A model of the continuous elastoplastic transition in metals

1971 ◽  
Vol 6 (3) ◽  
pp. 185-192 ◽  
Author(s):  
W J D Jones ◽  
A K Agarwal
Keyword(s):  
Yield Point ◽  
Strain Curve ◽  
Stress Strain Curve ◽  
Yield Strain ◽  
Stress Strain ◽  
Strain Behaviour ◽  
Aluminium Copper ◽  
Stress Cycling ◽  
Elastoplastic Transition ◽  
Plastic Parts

Part 1: The heterogeneous character of a real metal is represented by a model in which the metal is considered to consist of a large number of elements with a variation of individual stress-strain responses. The variation of Poisson's ratio which occurs as a function of strain is used to measure the progress of yielding through the material and hence to calculate the variation in elemental yield strains. By use of data obtained from the completely elastic and fully plastic parts of the stress-strain curve and the yield strain distribution, the elastoplastic transition behaviour can be calculated. Comparisons are presented between computed and experimental stress-strain curves for aluminium, copper, magnesium, nickel, and titanium alloy to demonstrate the validity of the proposed model. Part 2: Sufficient cyclic stressing can change the subsequent stress-strain curve of a steel which normally has a yield point into one with a continuous elastoplastic transition. A model of the elastoplastic transition in metals, developed by the authors in Part 1 to represent the stress-strain behaviour of metals with a continuous elastoplastic transition, is then proposed for representing the stress-strain behaviour of steels in which the yield point has been removed, by stress cycling. Results are presented to show good agreement between the model and the observed stress-strain behaviour of four steels, one of which had no yield point and the other three had their yield points removed by cyclic stressing.

An Indentation Theory Based on FEA Solutions for Material Property Evaluation

2002 ◽  
Author(s):  
Hyungyil Lee ◽  
Jin Haeng Lee
Keyword(s):  
Data Acquisition ◽  
Strain Curve ◽  
Strain Range ◽  
Numerical Approach ◽  
Average Error ◽  
Strain Hardening Exponent ◽  
Deformation Characteristics ◽  
Stress Strain Curve ◽  
Yield Strain ◽  
Property Evaluation

A new numerical approach of indentation theory is proposed by examining the finite element solutions based on the incremental plasticity theory with large geometry change. First the optimal data acquisition location is selected, where the strain gradient is the least and the effect of friction is negligible. This data acquisition point increases the strain range by a factor of five. Numerical regressions of obtained data exhibit that strain hardening exponent and yield strain are the two main parameters which govern the subindenter deformation characteristics. The new indentation theory successfully provides the stress-strain curve with an average error less than 3%.

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