Influence of strain rate on the mechanical response of nanostructured coppers elaborated by SPD and SPS

The influence of strain rate on the mechanical response of two different nanostructured pure coppers was investigated under uniaxial compression. The first nanostructured copper was elaborated by powder metallurgy using the Spark Plasma Sintering (SPS) process. The second nanostructured copper was elaborated by Severe Plastic Deformation (SPD). Conventional characterizations were conducted with quasi-static compression and tensile tests, hardness tests and, with microstructure analysis. The effect of strain rate was evaluated under uniaxial compression at strain rates varying from 10-4 to 10+4 s-1. The high strain rate data were generated with a direct Hopkinson impact technique. The increase of strength with strain rates was analysed and discussed from the Scanning Electron Microscope observations and grain size distribution. The mechanical properties are consequently dependent on the metallurgical history of these samples prepared according to two different routes.

Download Full-text

Spark Plasma Sintering and Strength Behavior under Compressive Loading of Mg-PSZ/Al2O3-TRIP-Steel Composites

Materials Science Forum ◽

10.4028/www.scientific.net/msf.825-826.182 ◽

2015 ◽

Vol 825-826 ◽

pp. 182-188 ◽

Cited By ~ 2

Author(s):

Lutz Krüger ◽

Steffen Grützner ◽

Sabine Decker ◽

Ines Schneider

Keyword(s):

Strain Rate ◽

Spark Plasma Sintering ◽

Trip Steel ◽

Volume Fraction ◽

Compressive Yield Strength ◽

Strain Rates ◽

Steel Matrix ◽

Trip Effect ◽

Plasma Sintering ◽

Spark Plasma

Composite materials, which consist of a metastable austenitic TRIP-steel matrix (CrMnNi TRIPsteel; TRansformation Induced Plasticity) reinforced by alumina particles (25 vol.% ceramic, designated as AT 25/75) and reinforced by alumina and MgO partially stabilized zirconia particles (Mg-PSZ) (35 vol.% ceramic, designated as AT 25/75 + MgPSZ) were synthesized through spark plasma sintering (SPS). In the AT 25/75 + MgPSZ, the steel particles were mainly surrounded by alumina. Hence, mostly steel/alumina and alumina/MgPSZ interfaces existed. The mechanical behavior of the as-sintered samples was characterized by compression tests at room temperature and 40 °C and in a range of strain rates between 103s-1and 103s1. The influence of the ceramic content, strain rate and temperature on TRIP-effect of the steel matrix was investigated. Due to the increasing ceramic volume fraction, AT 25/75 + MgPSZ exhibits the highest compressive yield strength under all loading conditions and no strain rate sensitivity. This composite showed no measurable TRIP-effect, due to the low fracture strain. The deformation-induced α’martensite within the steel particles in pure steel and AT 25/75 primary depends on the testing temperature and the strain rate. This is attributed to an increase of stacking fault energy with rising temperature. High strain rates cause adiabatic heating, counteracting the martensitic transformation.

Download Full-text

Compressive Mechanical Property Analysis of Eva Foam: Its Buffering Effects at Different Impact Velocities

Journal of Mechanics ◽

10.1017/jmech.2016.98 ◽

2016 ◽

Vol 33 (4) ◽

pp. 435-441

Author(s):

D.-S. Liu ◽

Z.-H. Chen ◽

C.-Y. Tsai ◽

R.-J. Ye ◽

K.-T. Yu

Keyword(s):

Strain Rate ◽

High Speed ◽

Mechanical Response ◽

Numerical Models ◽

Element Model ◽

Strain Rates ◽

Material Parameter Identification ◽

Strain Rate Effects ◽

Static Compression ◽

Strain Behavior

AbstractEVA foams, like all other polymers, also exhibit strain-rate effects and hysteresis. However, currently available approaches for predicting the mechanical response of polymeric foam subjected to an arbitrarily imposed loading history and strain-rate effect are highly limited. Especially, the strain rates in the intermediate rate domain (between 100and 102s–1) are extremely difficult to study. The use of data generated through the drop tower technique for implementation in constitutive equations or numerical models has not been considered in past studies. In this study, an experiment including a quasi-static compression test and drop impact tests with a high speed camera was conducted. An inverse analysis technique combined with a finite element model for material parameter identification was developed to determine the stress–strain behavior of foam at different specific strain rates. It was used in this study to simulate multiple loading and unloading cycles on foam specimens, and the results were compared with experimental measurements.

Download Full-text

Experimental Study on the Mechanical Behavior of EN08 Steel at Different Temperatures and Strain Rates

Metals ◽

10.3390/met8090736 ◽

2018 ◽

Vol 8 (9) ◽

pp. 736 ◽

Cited By ~ 4

Author(s):

Farid Abed ◽

Akrum Abdul-Latif ◽

Ayatollah Yehia

Keyword(s):

Strain Rate ◽

Mechanical Response ◽

Dynamic Compression ◽

Damage Model ◽

Tensile Tests ◽

Dynamic Strain ◽

Uniaxial Tensile ◽

Strain Rates ◽

Compression Tests ◽

Sem Images

The objective of this paper is to investigate the mechanical response of EN08 steel at quasi-static and dynamic strain rates. Uniaxial tensile tests under quasi-static regime (from 0.0015 s−1 to 0.15 s−1) are conducted on EN08 steel at a range of temperatures between 298 K and 923 K. Dynamic compression tests are also performed by using a drop hammer and by considering different masses and heights to study the material response at strain rates up to 800 s−1. Through the stress-strain responses of EN08 steel, a strong dependency of the yield stress as well as the ultimate strength on the strain rate and temperature is recognized. Furthermore, the strain hardening is highly affected by the increase of temperature at all levels of strain rate. The microstructure of the steel is also examined at a fracture by using SEM images to quantify the density of microdefects and define the damage evolution by using an energy-based damage model.

Download Full-text

Compressive Behaviour of Additively Manufactured Periodical Re-Entrant Tetrakaidecahedral Lattices at Low and High Strain-Rates

Metals ◽

10.3390/met11081196 ◽

2021 ◽

Vol 11 (8) ◽

pp. 1196

Author(s):

Michaela Neuhäuserová ◽

Tomáš Fíla ◽

Petr Koudelka ◽

Jan Falta ◽

Václav Rada ◽

...

Keyword(s):

Strain Rate ◽

Strain Rate Sensitivity ◽

High Speed ◽

Mechanical Response ◽

Split Hopkinson Pressure Bar ◽

Deformation Behaviour ◽

Rate Sensitivity ◽

Image Correlation ◽

Strain Rates ◽

Static Compression

Compressive deformation behaviour of additively manufactured lattice structures based on re-entrant tetrakaidecahedral unit-cell geometry were experimentally investigated under quasi-static and dynamic loading conditions. Specimens of four different structures formed by three-dimensional periodical assembly of selected unit-cells were produced by a laser powder bed fusion technique from a powdered austenitic stainless steel SS316L. Quasi-static compression as well as dynamic tests using split Hopkinson pressure bar (SHPB) apparatus at two strain-rates were conducted to evaluate the expected strain-rate sensitivity of the fundamental mechanical response of the structures. To evaluate the experiments, particularly the displacement fields of the deforming lattices, optical observation of the specimens using a high-resolution camera (quasi-static loading) and two synchronised high-speed cameras (SHPB experiments) was employed. An in-house digital image correlation algorithm was used in order to evaluate the anticipated auxetic nature of the investigated lattices. It was found that neither of the investigated structures exhibited auxetic behaviour although strain-rate sensitivity of the stress–strain characteristics was clearly identified for the majority of structures.

Download Full-text

Microstructure evolution of TC4 powder by spark plasma sintering after hot deformation

High Temperature Materials and Processes ◽

10.1515/htmp-2020-0002 ◽

2020 ◽

Vol 39 (1) ◽

pp. 457-465

Author(s):

Jiangpeng Yan ◽

Zhimin Zhang ◽

Jian Xu ◽

Yaojin Wu ◽

Xi Zhao ◽

...

Keyword(s):

Strain Rate ◽

Relative Density ◽

Spark Plasma Sintering ◽

Hot Deformation ◽

Tc4 Titanium Alloy ◽

Weave Structure ◽

Plasma Sintering ◽

Spark Plasma ◽

Average Relative Density ◽

Low Strain Rate

AbstractThe cylindrical samples of TC4 titanium alloy prepared by spark plasma sintering (SPS) were compressed with hot deformation of 70% on the thermosimulation machine of Gleeble-1500. The temperature of the processes ranged from 850°C to 1,050°C, and the strain rates varied between 0.001 and 5 s−1. The relative density of the sintered and compressed samples was measured by the Archimedes principle. During hot deformation, the microstructure of the sample was observed. The results show that the average relative density of the samples was 90.2% after SPS. And the relative density was about 98% after the hot deformation of 70%. Under high temperature (>950°C), the sensitivity of flow stress to temperature was reduced. At low strain rate (0.001 s−1), the increase in the deformation temperature promoted the growth of dynamic recrystallization (DRX). At the same temperature, the increase in strain rate slowed down the growth of DRX grains. And the variation tendency was shown from the basket-weave structure to the Widmanstätten structure at a low strain rate (<0.1 s−1), with increase in the strain rate.

Download Full-text

New Approach In The Properties Evaluation Of Ultrafine-Grained OFHC Copper

Archives of Metallurgy and Materials ◽

10.1515/amm-2015-0180 ◽

2015 ◽

Vol 60 (2) ◽

pp. 605-614 ◽

Cited By ~ 2

Author(s):

T. Kvačkaj ◽

A. Kováčová ◽

J. Bidulská ◽

R. Bidulský ◽

R. Kočičko

Keyword(s):

Mechanical Properties ◽

Strain Rate ◽

Tensile Tests ◽

Coarse Grained ◽

Wear Behaviour ◽

Ofhc Copper ◽

Strain Rates ◽

Ultrafine Grained ◽

Reduction Of Area ◽

Pin On Disk

AbstractIn this study, static, dynamic and tribological properties of ultrafine-grained (UFG) oxygen-free high thermal conductivity (OFHC) copper were investigated in detail. In order to evaluate the mechanical behaviour at different strain rates, OFHC copper was tested using two devices resulting in static and dynamic regimes. Moreover, the copper was subjected to two different processing methods, which made possible to study the influence of structure. The study of strain rate and microstructure was focused on progress in the mechanical properties after tensile tests. It was found that the strain rate is an important parameter affecting mechanical properties of copper. The ultimate tensile strength increased with the strain rate increasing and this effect was more visible at high strain rates$({\dot \varepsilon} \sim 10^2 \;{\rm{s}}^{ - 1} )$. However, the reduction of area had a different progress depending on microstructural features of materials (coarse-grained vs. ultrafine-grained structure) and introduced strain rate conditions during plastic deformation (static vs. dynamic regime). The wear behaviour of copper was investigated through pin-on-disk tests. The wear tracks examination showed that the delamination and the mild oxidational wears are the main wear mechanisms.

Download Full-text

The Effects of Physical Ageing and of Prior Immersion on the Esc Behaviour of Polycarbonate in Ethanol

MRS Proceedings ◽

10.1557/proc-305-211 ◽

1993 ◽

Vol 305 ◽

Author(s):

J. C. Arnold ◽

A. R. Eccott

Keyword(s):

Strain Rate ◽

Immersion Time ◽

Constant Strain Rate ◽

Tensile Tests ◽

Strain Rates ◽

Physical Ageing ◽

Diffusion Effects ◽

Craze Initiation ◽

Comparison Of Tests

AbstractThe effects of physical ageing and prior immersion time on the ESC behaviour of polycarbonate in ethanol were studied. Constant strain rate tensile tests were performed at a range of strain rates for samples with ageing times varying from 100 hours to 3000 hours and for prior immersion times of between 1 hour and 500 hours. Comparison of tests performed in ethanol and in air gave a good indication of the point of craze initiation. The results showed that there was a reduction in strain to crazing as the strain rate decreased, apart from with the lowest strain rate used. A longer prior immersion time also promoted craze formation. Both of these results are attributable to diffusion effects. Physical ageing had little effect on the ESC behaviour, due to the large amounts of deformation encountered in this system.

Download Full-text

Spark Plasma Sintering of Ti-4.5Al-3V-2Fe-2Mo (SP-700)

Materials Science Forum ◽

10.4028/www.scientific.net/msf.654-656.819 ◽

2010 ◽

Vol 654-656 ◽

pp. 819-822

Author(s):

Genki Kikuchi ◽

Hiroshi Izui ◽

Yuya Takahashi ◽

Shota Fujino

Keyword(s):

Spark Plasma Sintering ◽

Room Temperature ◽

Volume Fraction ◽

Titanium Boride ◽

Tensile Tests ◽

X Ray Diffraction ◽

X Ray ◽

Plasma Sintering ◽

Spark Plasma ◽

Tib2 Particles

In this study, we focused on the sintering performance of Ti-4.5Al-3V-2Mo-2Fe (SP-700) and mechanical properties of SP-700 reinforced with titanium boride (TiB/SP-700) fabricated by spark plasma sintering (SPS). TiB whiskers formed in titanium by a solid-state reaction of titanium and TiB2 particles were analyzed with scanning electron microscopy and X-ray diffraction. The TiB/SP-700 was sintered at temperatures of 1073, 1173, and 1273 K and a pressure of 70 MPa for 10, 30, and 50 min. The volume fraction of TiB ranged from 1.7 vol.% to 19.9 vol.%. Tensile tests of TiB/SP-700 were conducted at room temperature, and the effect of TiB volume fraction on the tensile properties was investigated.

Download Full-text

A Strain Rate-Dependent Damage Evolution Model for Concrete Based on Experimental Results

Advances in Civil Engineering ◽

10.1155/2021/6643263 ◽

2021 ◽

Vol 2021 ◽

pp. 1-8

Author(s):

Bin Xu ◽

Xiaoyan Lei ◽

P. Wang ◽

Hui Song

Keyword(s):

Strain Rate ◽

Uniaxial Compression ◽

Damage Evolution ◽

Damage Model ◽

Evolution Model ◽

Experimental Results ◽

Strain Rates ◽

Compression Tests ◽

Stress Strain ◽

Actual Damage

There are various definitions of damage variables from the existing damage models. The calculated damage value by the current methods still could not well correspond to the actual damage value. Therefore, it is necessary to establish a damage evolution model corresponding to the actual damage evolution. In this paper, a strain rate-sensitive isotropic damage model for plain concrete is proposed to describe its nonlinear behavior. Cyclic uniaxial compression tests were conducted on concrete samples at three strain rates of 10−3s−1, 10−4s−1, and 10−5s−1, respectively, and ultrasonic wave measurements were made at specified strain values during the loading progress. A damage variable was defined using the secant and initial moduli, and concrete damage evolution was then studied using the experimental results of the cyclic uniaxial compression tests conducted at the different strain rates. A viscoelastic stress-strain relationship, which considered the proposed damage evolution model, was presented according to the principles of irreversible thermodynamics. The model results agreed well with the experiment and indicated that the proposed damage evolution model can accurately characterize the development of macroscopic mechanical weakening of concrete. A damage-coupled viscoelastic constitutive relationship of concrete was recommended. It was concluded that the model could not only characterize the stress-strain response of materials under one-dimensional compressive load but also truly reflect the degradation law of the macromechanical properties of materials. The proposed damage model will advance the understanding of the failure process of concrete materials.

Download Full-text

Influence of strain rate and heat treatments on tensile and creep properties of Zn-0.15Cu-0.07Ti alloys

DYNA ◽

10.15446/dyna.v83n195.44926 ◽

2016 ◽

Vol 83 (195) ◽

pp. 77-83 ◽

Cited By ~ 1

Author(s):

María José Quintana Hernández ◽

José Ovidio García ◽

Roberto González Ojeda ◽

José Ignacio Verdeja

Keyword(s):

Strain Rate ◽

Room Temperature ◽

Rolling Direction ◽

Tensile Tests ◽

Strain Rates ◽

Creep Tests ◽

Design Problems ◽

Creep Properties ◽

Heat Treated ◽

Zn Alloys

The use of Cu and Ti in Zn alloys improves mechanical properties as solid solution and dispersoid particles (grain refiners) may harden the material and reduce creep deformation. This is one of the main design problems for parts made with Zn alloys, even at room temperature. In this work the mechanical behavior of a Zn-Cu-Ti low alloy is presented using tensile tests at different strain rates, as well as creep tests at different loads to obtain the value of the strain rate coefficient m in samples parallel and perpendicular to the rolling direction of the Zn strip. The microstructure of the alloy in its raw state, as well as heat treated at 250°C, is also analyzed, as the banded structure produced by rolling influences the strengthening mechanisms that can be achieved through the treatment parameters.

Download Full-text