scholarly journals Atomic Study on Tension Behaviors of Sub-10 nm NanoPolycrystalline Cu–Ta Alloy

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 3913 ◽  
Author(s):  
Weibing Li ◽  
Xiao Wang ◽  
Libo Gao ◽  
Yang Lu ◽  
Weidong Wang
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Strain Rate ◽  
Md Simulations ◽  
Good Explanation ◽  
Strength Increase ◽  
Flow Strength ◽  
Atomic Simulations ◽  
Effects Of Temperature ◽  
Stretching Process

Atomic simulations give a good explanation of the changes in the physical properties of a material. In this work, the tension behaviors of nanopolycrystalline Cu–Ta alloys are investigated through molecular dynamics (MD) simulations, and the influences of several important factors on the mechanical properties of the materials are studied. Firstly, nanopolycrystalline Cu–Ta (10 at %) alloy models with sub-10 nm grains are established by using the method of replacing the grain boundary atoms. Then, the effects of temperature, pressure, and strain rate on the mechanical properties of nanopolycrystalline Cu–Ta alloy are studied, and the elastic modulus and flow strength are obtained. The observations from the simulation results show that the elastic modulus and flow strength increase with the increasing of grain size for sub-10 nm nanopolycrystalline Cu–Ta alloys, and the elastic modulus increases firstly and then stabilizes as the strain rate increases. Finally, according to the evolution of dislocations and twin crystals, the plastic deformation mechanism of nanopolycrystalline Cu–Ta alloy during the stretching process is discussed in depth.

Mechanical Properties of ZDTP Tribofilms Measured by Nanoindentation: Strain Rate and Temperature Effects

2008 ◽  
Author(s):  
S. Bec ◽  
K. Demmou ◽  
J.-L. Loubet
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Strain Rate ◽  
Film Formation ◽  
Point Of View ◽  
Effect Of Temperature ◽  
Zinc Dialkyldithiophosphate ◽  
Wear Rates ◽  
Versus Strain ◽  
Antiwear Action

This study aims to contribute to better understand the antiwear action of zinc dialkyldithiophosphate (ZDTP) additives used in car engine lubrication. The antiwear action of ZDTP is associated to the formation of a protective tribofilm onto the rubbing surface. On a mechanical point of view, the efficiency of ZDTP tribofilms results from equilibrium between film formation and wear rates, associated with appropriate rheological properties. In this work, the mechanical properties of a ZDTP tribofilm have been measured by nanoindentation in different test conditions in order to investigate the effect of temperature and strain rate. A Nanoindenter XP® entirely set into a climatic chamber was used to perform the nanoindentation tests. For all tests, an increase of the elastic modulus was observed from a threshold contact pressure value. This effect is similar to the anvil effect observed on polymers: in confined geometry, the elastic modulus increases versus hydrostatic pressure. For the tribofilm, in the studied range, this effect is enhanced at high temperature and low strain rate. Furthermore, when the temperature increases, a change in the rheological behavior of the tribofilm is observed. Up to about 50°C, the tribofilm exhibits viscoplastic behavior — the hardness increases versus strain rate — and above 50°C, the hardness decreases versus strain rate (“shear thinning-like” behavior).

Effects of Temperature and Strain Rate on Compressive Mechanical Properties of Ultrafine-Grained CP Titanium

2007 ◽  
Vol 26-28 ◽  
pp. 381-384 ◽  
Author(s):  
Zhi Guo Fan ◽  
Chao Ying Xie
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Ultimate Strength ◽  
Room Temperature ◽  
Equal Channel Angular Extrusion ◽  
Coarse Grain ◽  
Ultrafine Grained ◽  
Effects Of Temperature ◽  
Cp Ti ◽  
Compressive Tests

Ultrafine-grained (UFG) CP Ti were successfully prepared by Equal Channel Angular Extrusion (ECAE) at 390°C~400°C, small than 0.5 um in size. The compressive tests for coarse grain (CG) and UFG Ti were carried out at room temperature (RT) and 77K. UFG Ti showed excellent ductility and higher strength than CG Ti at RT and 77 K. The strain hardening of UFG Ti was improved at 77 K. The compressive ultimate strengths of CG Ti and UFG Ti were both enhanced as the strain rate increased, but CG Ti showed more obvious temperature and strain rate dependence of flow stress, comparing with UFG Ti. When the strain rate increased to 1×10-1/s, the compressive ultimate strength of UFG Ti was kept almost constant, while the ultimate strength of CG Ti increased to the strength level of UFG Ti.

Molecular dynamics study on the tensile properties of graphene/Cu nanocomposite

2017 ◽  
Vol 06 (03) ◽  
pp. 1750021 ◽  
Author(s):  
Jun Hua ◽  
Zhirong Duan ◽  
Chen Song ◽  
Qinlong Liu
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Tensile Strength ◽  
Elastic Modulus ◽  
Comparative Analysis ◽  
Strain Rate ◽  
Ultimate Strength ◽  
Strain Rates ◽  
Single Crystal Copper ◽  
Single Slice

In this paper, the mechanical properties, including elastic properties, deformation mechanism, dislocation formation and crack propagation of graphene/Cu (G/Cu) nanocomposite under uniaxial tension are studied by molecular dynamics (MD) method and the strain rate dependence is also investigated. Firstly, through the comparative analysis of tensile results of single crystal copper (Cu), single slice graphene/Cu (SSG/Cu) nanocomposite and double slice graphene/Cu (DSG/Cu) nanocomposite, it is found that the G/Cu nanocomposites have larger initial equivalent elastic modulus and tensile ultimate strength comparing with Cu and the more content of graphene, the greater the tensile strength of composites. Afterwards, by analyzing the tensile results of SSG/Cu nanocomposite under different strain rates, we find that the tensile ultimate strength of SSG/Cu nanocomposite increases with the increasing of strain rate gradually, but the initial equivalent elastic modulus basically remains unchanged.

Experimental Investigation on the Dynamic Properties and Failure Mode of Carbon Fiber Reinforced Thermoplastic Composites

2014 ◽  
Vol 697 ◽  
pp. 102-108
Author(s):  
Jian Hua Ning
Keyword(s):  
Mechanical Properties ◽  
Carbon Fiber ◽  
Strain Rate ◽  
Failure Modes ◽  
Thermoplastic Composites ◽  
Elastic Model ◽  
Strength Increase ◽  
Fiber Reinforced ◽  
Carbon Fiber Reinforced ◽  
Constitute Model

Owing to the excellent mechanical properties and formability of carbon fiber reinforced thermoplastic composites, this composite has been applied in car industry. The static and dynamic mechanical properties of the composites are investigated under strain-rate from 0.001/s to 50/s. The experimental results show that the elastic model and tensile strength increase with the increase of strain rate, and show that the composite has remarkable rate-hardening effect. A constitute model that including rate-dependent effect is applied to present the strain-stress curve of the composite. The constitute model provides accurate constitute function for finite element analysis of the composite.. The microstructure of the composite is also investigated with scanning electric microscope, and the failure modes are discussed. The investigation provides the basis for engineering application of the composite.

scholarly journals Compressive Behavior of Carbon Nanotube Reinforced Polypropylene Composites Under High Strain Rate: Insights From Molecular Dynamics

2021 ◽  
Author(s):  
Brijesh Mishra ◽  
Sumit Sharma
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotube ◽  
Strain Rate ◽  
Compressive Strain ◽  
Md Simulations ◽  
Vital Role ◽  
Key Factors ◽  
Single Walled Carbon Nanotube ◽  
Vacancy Defects ◽  
Polypropylene Composites

Abstract Since the discovery of carbon nanotubes (CNTs), these have received a lot of attention because of their unusual mechanical electrical properties. Strain rate is one of the key factors that play a vital role in enhancing the mechanical properties of nanocomposites. In this study, (4, 4) armchair single-walled carbon nanotube (SWCNT) was employed with the polymer matrix as polypropylene (PP). The influence of compressive strain rate on SWCNT/PP nanocomposites was evaluated using MD simulations, and mechanical properties have been predicted. Stone-Wales (SW) and vacancy defects, were integrated on the SWCNT. The maximum Young’s modulus (E) of 81.501 GPa was found for the pristine SWCNT/PP composite for a strain rate of 1010 s-1. The least value of E was 45.073GPa for 6% SW defective/PP composite for a strain rate of 108 s-1. While the 6% vacancy defective CNT/PP composite showed the lowest value of E as 39.57GPa for strain rate 108 s-1. It was found that the mechanical properties of SWCNT/PP nanocomposites decrease with the increase in percent defect. It was also seen that the mechanical properties were enhanced with the increment in the applied strain rate. The results obtained from this study could be useful for the researchers designing PP-based materials for compression loading to be used for biomedical applications.

scholarly journals SHPB Testing and Analysis of Bedded Shale under Active Confining Pressure

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Guoliang Yang ◽  
Jingjiu Bi ◽  
Xuguang Li ◽  
Jie Liu ◽  
Yanjie Feng
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Strain Rate ◽  
Peak Stress ◽  
Confining Pressure ◽  
Dynamic Mechanical Properties ◽  
Dynamic Elastic Modulus ◽  
Peak Strain ◽  
Dynamic Mechanical ◽  
Bedding Angle

Shale gas is the most important new energy source in the field of energy, and its exploitation is very important. The research on the dynamic mechanical properties of shale is the premise of exploitation. To study the dynamic mechanical properties of shale from the Changning-Weiyuan area of Sichuan Province, China, under confining pressure, we used a split Hopkinson pressure bar (SHPB) test system with an active containment device to carry out dynamic compression tests on shale with different bedding angles. (1) With active confining pressure, the shale experiences a high strain rate, and its stress-strain curve exhibits obvious plastic deformation. (2) For the same impact pressure, the peak stress of shale describes a U-shaped curve with an increasing bedding angle; besides, the peak stress of shale with different bedding angles increases linearly with rising confining pressure. The strain rate shows a significant confining pressure enhancement effect. With active confining pressure, the peak strain gradually decreases as the bedding angle increases. (3) As a result of the influence of different bedding angles, the dynamic elastic modulus of shale has obvious anisotropic characteristics. Shale with different bedding angles exhibits different rates of increase in the dynamic elastic modulus with rising confining pressure, which may be related to differences in the development of planes of weakness in the shale. The results of this study improve our understanding of the behavior of bedded shale under stress.

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