Temperature Effects and Fast-Moving Screw Dislocations at High Strain Rate Deformations

1998 ◽  
Vol 538 ◽  
Author(s):  
A. Roos ◽  
E.D. Metselaar ◽  
J.TH.M. De Hosson ◽  
H.H.M. Cleveringa ◽  
E. Van Der Giessen
Keyword(s):  
Temperature Rise ◽  
Temperature Effects ◽  
High Strain ◽  
Strain Rates ◽  
Displacement Fields ◽  
Screw Dislocations ◽  
Discrete Dislocation ◽  
Dislocation Plasticity ◽  
Stress And Displacement Fields ◽  
Inclined Planes

AbstractIn this paper, shear deformation at high strain rates is modeled within the framework of discrete dislocation plasticity. The method of discrete dislocation plasticity is extended to incorporate the temperature rise induced by moving dislocations. Also, the stress and displacement fields of a screw dislocation on inclined planes in a periodic structure are developed. The influence on the temperature rise on various micro-mechanical processes is discussed.

Discrete Dislocation Plasticity Approach to Fast Moving Dislocations

1999 ◽  
Vol 578 ◽  
Author(s):  
A. Roos ◽  
E. Metselaar ◽  
J.Th.M. De Hosson ◽  
E. van der Giessen
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Strain Rates ◽  
Two Dimensional ◽  
Relativistic Case ◽  
Discrete Dislocation ◽  
Dislocation Plasticity ◽  
Isotropic Elasticity ◽  
Very High

AbstractThis paper concentrates on application of the so-called Discrete Dislocation Plasticity to high strain rate deformations. In particular the question is addressed if the DDP approach may capture the specific processes taking place at high strain rates. In particular the paper reports on tests of the validity of some approximations and provides some sample runs to show the applicability of the method. In assessing the results, one has to keep in mind two underpinning aspects: (1) the model is two-dimensional and (2) the results hold only in the regime where linear isotropic elasticity is valid. It was concluded that accelerations can not be neglected at very high strain rate deformations, both for the conventional and the relativistic case.

Low-Temperature Effects on E-glass/Urethane at High Strain Rates

AIAA Journal ◽  
2004 ◽  
Vol 42 (5) ◽  
pp. 1050-1053 ◽  
Author(s):  
Shunjun Song ◽  
Jack R. Vinson ◽  
Roger M. Crane
Keyword(s):  
Low Temperature ◽  
Temperature Effects ◽  
High Strain ◽  
Strain Rates ◽  
High Strain Rates

Temperature Rise in Polymeric Materials During High Rate Deformation

2008 ◽  
Vol 75 (1) ◽  
Author(s):  
M. Garg ◽  
A. D. Mulliken ◽  
M. C. Boyce
Keyword(s):  
Strain Rate ◽  
Temperature Rise ◽  
High Strain ◽  
Split Hopkinson Pressure Bar ◽  
Polymeric Materials ◽  
Test System ◽  
High Rate ◽  
Single Element ◽  
Strain Rates ◽  
Work Of Deformation

Many polymeric materials undergo substantial plastic strain prior to failure. Much of this post yield deformation is dissipative and, at high strain rates, will result in a substantial temperature rise in the material. In this paper, an infrared (IR) detector system is constructed to measure the rise in temperature of a polymer during high strain rate compression testing. Temperature measurements were made using a high-speed mercury-cadmium-telluride (HgCdTe) single-element photovoltaic detector sensitive in the mid-infrared spectrum (6–12μm), while mechanical deformation was accomplished in a split Hopkinson pressure bar (SHPB). Two representative polymers, an amorphous thermoplastic (polycarbonate (PC)) and a thermoset epoxy (EPON 862/W), were tested in uniaxial compression at strain rates greater than 1000s−1 while simultaneously measuring the specimen temperature as a function of strain. For comparison purposes, analogous measurements were conducted on these materials tested at a strain rate of 0.5s−1 on another test system. The data are further reduced to energy quantities revealing the dissipative versus storage character of the post yield work of deformation. The fraction of post yield work that is dissipative was found to be a strong function of strain for both polymers. Furthermore, a greater percentage of work is found to be dissipative at high rates of strain (>1000s−1) than at the lower rate of strain (0.5s−1) for both polymers; this is consistent with the need to overcome an additional energy barrier to yield at strain rates greater than 100s−1 in these two polymers. The highly cross-linked thermoset polymer was found to store a greater percentage of the post yield work of deformation than the physically entangled thermoplastic.

scholarly journals Strain-Rate-Dependent Tensile Response of Ti–5Al–2.5Sn Alloy

Materials ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 659 ◽  
Author(s):  
Bin Zhang ◽  
Jin Wang ◽  
Yang Wang ◽  
Yu Wang ◽  
Ziran Li
Keyword(s):  
Strain Rate ◽  
Strain Hardening ◽  
Uniaxial Tension ◽  
Temperature Rise ◽  
High Strain ◽  
Adiabatic Temperature ◽  
High Rate ◽  
Strain Rates ◽  
High Strain Rates ◽  
Adiabatic Temperature Rise

This study is an experimental investigation on the tensile responses of Ti–5Al–2.5Sn alloy over a wide range of strain rates. Uniaxial tension tests within the rate range of 10−3–101 s−1 are performed using a hydraulic driven MTS810 machine and a moderate strain-rate testing system. The high-rate uniaxial tension and tension recovery tests are conducted using a split-Hopkinson tension bar to obtain the adiabatic and isothermal stress–strain responses of the alloy under dynamic loading conditions. The experimental results show that the value of the initial yield stress increases with the increasing strain rate, while the strain rate sensitivity is greater at high strain rates. The isothermal strain-hardening behavior changes little with the strain rate, and the adiabatic temperature rise is the main reason for the reduction of the strain-hardening rate during high strain-rate tension. The electron backscatter diffraction (EBSD) analysis of the post-deformed samples indicates that there are deformation twins under quasi-static and high-rate tensile loadings. Scanning electron microscope (SEM) micrographs of the fracture surfaces of the post-deformed samples show dimple-like features. The Zerilli–Armstrong model is modified to incorporate the thermal-softening effect of the adiabatic temperature rise at high strain rates and describe the tension responses of Ti–5Al–2.5Sn alloy over strain rates from quasi-static to 1050 s−1.

The Role of Homogeneous Nucleation in Planar Dynamic Discrete Dislocation Plasticity

2015 ◽  
Vol 82 (7) ◽  
Author(s):  
Benat Gurrutxaga-Lerma ◽  
Daniel S. Balint ◽  
Daniele Dini ◽  
Daniel E. Eakins ◽  
Adrian P. Sutton
Keyword(s):  
Homogeneous Nucleation ◽  
Dislocation Dynamics ◽  
Plastic Relaxation ◽  
Strain Rates ◽  
Dislocation Generation ◽  
Discrete Dislocation Dynamics ◽  
Discrete Dislocation ◽  
Dislocation Plasticity ◽  
Dislocation Densities

Homogeneous nucleation of dislocations is the dominant dislocation generation mechanism at strain rates above 108 s−1; at those rates, homogeneous nucleation dominates the plastic relaxation of shock waves in the same way that Frank–Read sources control the onset of plastic flow at low strain rates. This article describes the implementation of homogeneous nucleation in dynamic discrete dislocation plasticity (D3P), a planar method of discrete dislocation dynamics (DDD) that offers a complete elastodynamic treatment of plasticity. The implemented methodology is put to the test by studying four materials—Al, Fe, Ni, and Mo—that are shock loaded with the same intensity and a strain rate of 1010 s−1. It is found that, even for comparable dislocation densities, the lattice shear strength is fundamental in determining the amount of plastic relaxation a material displays when shock loaded.

scholarly journals Strain Rate and Temperature Effects on Tensile Properties of Polycrystalline Cu6Sn5 by Molecular Dynamic Simulation

Crystals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1415
Author(s):  
Wei Huang ◽  
Kailin Pan ◽  
Jian Zhang ◽  
Yubing Gong
Keyword(s):  
Strain Rate ◽  
Tensile Properties ◽  
Young’S Modulus ◽  
Temperature Effects ◽  
High Strain ◽  
Young's Modulus ◽  
Voronoi Tessellation ◽  
Strain Rates ◽  
Electronic Products ◽  
Electrical Connections

Intermetallic compounds (IMCs) are essential in the soldering of electronic products and are composed mainly of Cu6Sn5 and Cu3Sn. They must maintain reliable mechanical and electrical connections. As they are usually only a few microns thick, and it is difficult to study their mechanical properties by traditional methods. In this study, a 100 Å × 100 Å × 100 Å polycrystal with 10 grains was created by Atomsk through Voronoi tessellation based on a Cu6Sn5 unit cell. The effects of the temperature and strain rate on the tensile properties of the polycrystalline Cu6Sn5 were analyzed based on MEAM potential function using a molecular dynamics (MD) method. The results show that Young’s modulus and ultimate tensile strength (UTS) of the polycrystalline Cu6Sn5 decrease approximately linearly with an increase in temperature. At high strain rates (0.001–100 ps−1), Young’s modulus and UTS of the Cu6Sn5 are logarithmic with respect to the strain rate, and both increase with an increase in strain rate. In addition, at low strain rates (0.00001–0.0005 ps−1), the UTS has a quadratic increase as the strain rate increases.

scholarly journals Predicting the flow stress and dominant yielding mechanisms: analytical models based on discrete dislocation plasticity

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Jianqiao Hu ◽  
Hengxu Song ◽  
Zhanli Liu ◽  
Zhuo Zhuang ◽  
Xiaoming Liu ◽  
...  
Keyword(s):  
Sample Size ◽  
Dislocation Dynamics ◽  
Analytical Models ◽  
Material Strength ◽  
Physical Parameters ◽  
Strain Rates ◽  
Collective Interaction ◽  
Discrete Dislocation ◽  
Dislocation Plasticity ◽  
Nucleation Mechanisms

AbstractDislocations are the carriers of plasticity in crystalline materials. Their collective interaction behavior is dependent on the strain rate and sample size. In small specimens, details of the nucleation process are of particular importance. In the present work, discrete dislocation dynamics (DDD) simulations are performed to investigate the dominant yielding mechanisms in single crystalline copper pillars with diameters ranging from 100 to 800 nm. Based on our simulations with different strain rates and sample size, we observe a transition of the relevant nucleation mechanism from “dislocation multiplication” to “surface nucleation”. Two physics-based analytical models are established to quantitatively predict this transition, showing a good agreement for different strain rates with our DDD simulation data and with available experimental data. Therefore, the proposed analytical models help to understand the interplay between different physical parameters and nucleation mechanisms and are well suitable to estimate the material strength for different material properties and under given loading conditions.

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