Atomistic Study on Nano Stress-Strain Curves of α-Fe

1997 ◽  
Vol 492 ◽  
Author(s):  
Shenyang Hu ◽  
Matthias Ludwig ◽  
Liam Farrissey ◽  
Siegfried Schmauder
Keyword(s):  
Boundary Conditions ◽  
Tensile Deformation ◽  
Tensile Axis ◽  
Plane Boundary ◽  
Uniaxial Tensile ◽  
Stress Strain ◽  
Fracture Characteristics ◽  
Deformation And Fracture ◽  
Dislocation Movement ◽  
Atomistic Study

ABSTRACTThe atomistic processes and stress-strain-curves during uniaxial tensile deformation of a single α-Fe nanocrystal have been studied with the molecular static method. Periodic boundary conditions are imposed along one direction perpendicular to the tensile axis to model plane strain conditions. The effects of the model sizes in plane, boundary conditions and crystal orientations on the stress-strain curves are systematically analyzed. Various deformation evidences such as dislocation movement, dislocation piling up and twinning are clearly observed. The deformation and fracture characteristics of a-Fe and their dependencies on the boundary conditions are investigated.

Effect of Temperatures on Tensile of Aluminium Thin Films

2012 ◽  
Vol 528 ◽  
pp. 135-139 ◽  
Author(s):  
Qiao Neng Guo ◽  
Shi E Yang ◽  
Qiang Sun ◽  
Yu Jia ◽  
Yu Ping Huo
Keyword(s):  
Thin Films ◽  
Molecular Dynamics ◽  
Maximum Stress ◽  
Tensile Deformation ◽  
Uniaxial Extension ◽  
Strain Curve ◽  
Local Maximum ◽  
Temperature Curve ◽  
Uniaxial Tensile ◽  
Stress Strain

The mechanical process of single-crystal aluminium thin films under uniaxial tensile strain was simulated with molecular dynamics method at different temperature. The stress–strain curve and potential energy–strain curve of thin aluminium film under uniaxial tensile deformation were obtained by molecular dynamics simulations. With the changes of sample temperatures in uniaxial extension, the variation characteristics of stress–strain curves are alike at the elastic stage and different at the plastic one below and above 370 K, respectively. From the stress–strain curves, we gained the first local maximum stress-temperature curve and the strain at the first local maximum stress-temperature curve, and found that the strange temperature dependence of first local maximum stress: when the temperature is above 370 K, the stress goes down quickly with temperature, and when below 370 K, it descends slowly. With increasing temperature, the difference between two strain values corresponding to two maximal potential energies changes slowly below and above 370K but it goes up quickly about 370K. By these dependences, we have identified the critical temperature （370K） for the transition of plastic flow mechanism.

Anomalous Twinning as the Macroscopic Deformation Mechanism for AZ31 Magnesium Alloy

2019 ◽  
Vol 810 ◽  
pp. 95-100
Author(s):  
Yusuke Onuki ◽  
Shigeo Sato
Keyword(s):  
Magnesium Alloy ◽  
Deformation Mechanism ◽  
Tensile Deformation ◽  
Tensile Axis ◽  
Rolling Direction ◽  
Az31 Magnesium Alloy ◽  
Uniaxial Tensile ◽  
Rolled Sheet ◽  
Prism Slip ◽  
Texture Measurement

In order to study the plastic deformation mechanism of AZ31 magnesium alloy, in situ texture measurement during uniaxial tensile deformation is conducted by using neutron diffraction. The specimen is prepared from a rolled sheet so that the deformation axis is parallel to the rolling direction. By increasing strain, the alignment of <10-10> along the tensile axis is strengthened, which is due to the activation of the prism slip system. The basal pole concentration at the prior sheet normal direction is slightly decreased by the deformation and the new texture component is formed at the transvers direction. This can be understood by activation of the {10-12} tension twinning. These results indicate that the tension twinning plays an important role even when the tensile deformation is applied parallel to the basal plane.

Experimental Research on Grain Orientation Evolution of Extruded Mg Alloy AZ31B Sheet during Uniaxial Tensile Deformation

2008 ◽  
Vol 32 ◽  
pp. 87-92
Author(s):  
Shi Hong Zhang ◽  
Zhang Gang Li
Keyword(s):  
Room Temperature ◽  
Tensile Deformation ◽  
Tensile Axis ◽  
Mg Alloy ◽  
Uniaxial Tensile ◽  
Slip Systems ◽  
Close Relationship ◽  
Crystal Model ◽  
Ebsd Technique ◽  
Axis Rotation

The orientation rotation in extruded Mg alloy AZ31B sheets during uniaxial tension at room temperature has been investigated using SEM/EBSD technique. According to the experimental results and the calculated results of Sachs crystal model, the quantitative rule of the tensile axis rotation for the grains (parent), and the associated slip systems have been analyzed in detail. The influencing factors of twinning area fraction have also been studied. The results show that the rule of the rotation of tensile axis can be explained by cross slip systems; the grains with different initial orientations exhibit different twinning behaviors; the area fractions of extensive twins have a close relationship with Schmid factors of tensile twinning, and with the angle between c-axis and tensile axis of the grains.

scholarly journals Deformation Behavior Causing Excessive Thinning of Outer Diameter of Micro Metal Tubes in Hollow Sinking

Metals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1315
Author(s):  
Takuma Kishimoto ◽  
Hayate Sakaguchi ◽  
Saki Suematsu ◽  
Kenichi Tashima ◽  
Satoshi Kajino ◽  
...  
Keyword(s):  
Deformation Behavior ◽  
Tensile Deformation ◽  
Elastic Recovery ◽  
Strain Curve ◽  
Uniaxial Tensile ◽  
Outer Diameter ◽  
Stress Strain ◽  
Drawing Stress ◽  
Yielding Behavior ◽  
Diameter Reduction

The deformation behavior of microtubes during hollow sinking was investigated to clarify the mechanism of the excessive thinning of their outer diameters. Stainless-steel, copper, and aluminum alloy tubes were drawn without an inner tool to evaluate the effect of Lankford values on outer diameter reduction. Drawing stress and stress-strain curves were obtained to evaluate the yielding behavior during hollow sinking. The observed yielding behavior indicated that the final outer diameter of the drawn tube was always smaller than the die diameter due to the uniaxial tensile deformation starting from the die approach end even though the drawing stress was in the elastic range. The results of a loading-unloading tensile test demonstrated that the strain remained even after unloading. Therefore, the outer diameter is considered to become smaller than the die diameter during hollow sinking due to microscopic yielding at any Lankford value. Furthermore, the outer diameter becomes smaller than the die diameter as the Lankford value increases, as theorized. As the drawing stress decreases or the apparent elastic modulus of the stress-strain curve increases, the outer diameter seems to approach the die diameter during unloading, which is caused by the elastic recovery outside the microscopic yielding region.

scholarly journals Uniaxial Tensile Deformation And Fracture Process of Structures Forming By Unsaturated Intercalation of Amine Molecule Into C–S–H Gel

2021 ◽  
Author(s):  
Dawei sun ◽  
Yan Zheng ◽  
Jianhua Yan ◽  
Yali Wang ◽  
Jianfeng Wang ◽  
...  
Keyword(s):  
Fracture Process ◽  
Tensile Deformation ◽  
Mean Square Displacement ◽  
Local Stress ◽  
Dynamics Simulation ◽  
Elastic Behavior ◽  
Uniaxial Tensile ◽  
Deformation And Fracture ◽  
Amine Molecule ◽  
Interlayer Region

Abstract The application of cement based materials in engineering requires the understanding of their characteristics and subsequent deformation and fracture process of C-S-H gel in service. In this work, three types of amine molecules including TEPA, PAM and TEA were intercalated unsaturatedly into C–S–H gel successfully. Systematical analysis was performed on the structures and properties on both C–S–H gel and corresponding amine molecules / C–S–H gel. It was found that unsaturated intercalation of amine molecules into C–S–H gel plays a key role in the geometry and therein density of nanocomposites. Subsequently, radial distribution function (RDF), time correlated function (TCF) and mean square displacement (MSD) were applied to characterize the structure and dynamic information of the as-generated nanocomposites, demonstrating the occurance of interaction between amine molecules with Ca–Si layer and acceleration of water diffusion by unsaturated intercalation of amine molecules into the interlayer region in C–S–H gel. Finally, deformation and fracture process of C–S–H gel and amine molecules / C–S–H gel under uniaxial tensile loads were displayed by molecular dynamics simulation. It was indicated that Young’s modulus of nanocomposites demonstrates a strain softening nature, indicating a visco-elastic behavior. The breakage of Ca–O bonds and hydrogen bonds dominates the fracture of C–S–H gel. Weak interaction for TEPA / C–S–H gel or TEA / C–S–H gel leads to a decreased tensile strength. Local stress concentration in other interlayer region governs the deformation and fracture process in spite of the formation of strong interaction between double bonded polar oxygen atoms in PAM molecules and Ca atoms in C–S–H gel.

Effect of network structure from different processing conditions on the mechanical property of semi-crystalline polymers

2014 ◽  
Vol 1619 ◽  
Author(s):  
Xin Dong ◽  
David McDowell ◽  
Karl Jacob
Keyword(s):  
Mechanical Property ◽  
Strain Hardening ◽  
Mechanical Response ◽  
Tensile Deformation ◽  
Processing Condition ◽  
Constant Stress ◽  
Uniaxial Tensile ◽  
Initial Structure ◽  
Stress Strain ◽  
Strain Hardening Behavior

ABSTRACTSemi-crystalline structures were prepared from different processing condition. Biaxial oriented melt were crystallized at 375 K and atmospheric pressure for 10 nanoseconds (ns), to generate a lamellar semi-crystalline structure. Similar structures were also prepared from deformation of a cubic amorphous initial structure isothermally at 375 K. For comparison, two different thermostats, the constant stress (NPT) and constant volume (NVT) conditions were applied to the system during 10 ns of crystallization. The semi-crystalline samples shared common morphological features such as in the crystallinity, crystal orientation, lamellae thickness and density distribution, etc. However, during the subsequent uniaxial tensile deformation test of the samples to strain of 0.5, different stress-strain behaviors were demonstrated. By combining the observations of morphologies during deformation tests and analysis of the stress-strain curves, conclusions were made that the effectiveness of the network had a strong influence on the mechanical property and strain hardening behavior. The oriented network from the constant stress crystallization, owing to the taut chains, gave rise to optimal mechanical response with substantial strain-hardening.

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