scholarly journals Review of Size Effects during Micropillar Compression Test: Experiments and Atomistic Simulations

Crystals ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 591 ◽  
Author(s):  
Shahbeyk ◽  
Voyiadjis ◽  
Habibi ◽  
Astaneh ◽  
Yaghoobi
Keyword(s):  
Compression Test ◽  
Size Effects ◽  
Theoretical Models ◽  
Atomistic Simulations ◽  
Compression Tests ◽  
Pillar Diameter ◽  
Recent Computer ◽  
Properties Of Materials ◽  
Micropillar Compression ◽  
Work First

The micropillar compression test is a novel experiment to study the mechanical properties of materials at small length scales of micro and nano. The results of the micropillar compression experiments show that the strength of the material depends on the pillar diameter, which is commonly termed as size effects. In the current work, first, the experimental observations and theoretical models of size effects during micropillar compression tests are reviewed in the case of crystalline metals. In the next step, the recent computer simulations using molecular dynamics are reviewed as a powerful tool to investigate the micropillar compression experiment and its governing mechanisms of size effects.

Evaluation of Micro-Pillar Compression Tests for Accurate Determination of Elastic-Plastic Constitutive Relations

2012 ◽  
Vol 79 (6) ◽  
Author(s):  
Huiyang Fei ◽  
Amit Abraham ◽  
Nikhilesh Chawla ◽  
Hanqing Jiang
Keyword(s):  
Mechanical Properties ◽  
Finite Element Analysis ◽  
Compression Test ◽  
Constitutive Relations ◽  
Accurate Determination ◽  
Compression Tests ◽  
Element Analysis ◽  
Plastic Materials ◽  
Properties Of Materials

The micro-pillar compression test is emerging as a novel way to measure the mechanical properties of materials. In this paper, we systematically conducted finite element analysis to evaluate the capability of using a micro-compression test to probe the mechanical properties of both elastic and plastic materials. We found that this test can provide an alternative way to accurately and robustly measure strain, and to some extent, stress. Therefore, this test can be used to measure some strain related quantities, such as strain to failure, or the stress-strain relations for plastic materials.

scholarly journals Room-temperature deformation of single crystals of ZrB2 and TiB2 with the hexagonal AlB2 structure investigated by micropillar compression

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Zhenghao Chen ◽  
Bhaskar Paul ◽  
Sanjib Majumdar ◽  
Norihiko L. Okamoto ◽  
Kyosuke Kishida ◽  
...  
Keyword(s):  
Single Crystals ◽  
Plastic Flow ◽  
Room Temperature ◽  
Resolve Shear Stress ◽  
Temperature Deformation ◽  
Slip Systems ◽  
Compression Tests ◽  
Plastic Deformation Behavior ◽  
Bulk Single Crystals ◽  
Micropillar Compression

AbstractThe plastic deformation behavior of single crystals of two transition-metal diborides, ZrB2 and TiB2 with the AlB2 structure has been investigated at room temperature as a function of crystal orientation and specimen size by micropillar compression tests. Although plastic flow is not observed at all for their bulk single crystals at room temperature, plastic flow is successfully observed at room temperature by the operation of slip on {1$${\bar{1}}$$ 1 ¯ 00}<11$${\bar{2}}$$ 2 ¯ 3> in ZrB2 and by the operation of slip on {1$${\bar{1}}$$ 1 ¯ 00}<0001> and {1$${\bar{1}}$$ 1 ¯ 00}<11$${\bar{2}}$$ 2 ¯ 0> in TiB2. Critical resolve shear stress values at room temperature are very high, exceeding 1 GPa for all observed slip systems; 3.01 GPa for {1$${\bar{1}}$$ 1 ¯ 00}<11$${\bar{2}}$$ 2 ¯ 3> slip in ZrB2 and 1.72 GPa and 5.17 GPa, respectively for {1$${\bar{1}}$$ 1 ¯ 00}<0001> and {1$${\bar{1}}$$ 1 ¯ 00}<11$${\bar{2}}$$ 2 ¯ 0> slip in TiB2. The identified operative slip systems and their CRSS values are discussed in comparison with those identified in the corresponding bulk single crystals at high temperatures and those inferred from micro-hardness anisotropy in the early studies.

Evaluation of Friction Properties of Magnesium Alloy during Hot Forging by Ring Compression Test

2017 ◽  
Vol 889 ◽  
pp. 119-126
Author(s):  
Sueji Hirawatari ◽  
Hisaki Watari ◽  
Shinichi Nishida ◽  
Yuki Sato ◽  
Mayumi Suzuki
Keyword(s):  
Magnesium Alloys ◽  
Compression Test ◽  
Hot Forging ◽  
Hot Forming ◽  
Compression Tests ◽  
Ring Compression Test ◽  
Stress Strain ◽  
Friction Coefficients ◽  
Ring Compression ◽  
Velocity Motion

This paper deals with friction properties and deformation resistance during hot forming of Mg-Al-Ca-Mn series magnesium alloys. Friction coefficients between dies and magnesium alloys were obtained by ring compression tests that used graphite, PTFE, and an oil lubricant in a hot-forging process. Hot forging was performed under various conditions to clarify the effects of types of lubricants and slide motion of the press machines on friction properties. Two types of slide motion, a constant velocity motion and a pulse motion were selected in the ring-compression test. It was found that graphite with an oil lubricant effectively eliminated die sticking in hot forming of magnesium alloys. The isothermal deformation resistances were derived using friction coefficients obtained by ring-compression tests as well as finite-element simulations. The predicted stress strain curves with temperature were examined with the stress-strain relationship obtained in experiments using a servo press and demonstrated the effectiveness of the proposed method.

scholarly journals Experimental study on the compression characteristics of soft soil based on low temperature effect

2021 ◽  
Vol 9 (4B) ◽  
Author(s):  
Jian Zhang ◽  
◽  
Chunpeng Han ◽  
Jiayi Tian ◽  
Qingjie Dong ◽  
...  
Keyword(s):  
Low Temperature ◽  
Phase Change ◽  
Compression Test ◽  
Variable Temperature ◽  
Soft Soil ◽  
Test Methods ◽  
Variable Load ◽  
Compression Tests ◽  
Different Temperatures ◽  
Freezing Condition

Based on the characteristics of long annual freezing time and short suitable construction period of soft soil in cold region, this paper discusses the feasibility of foundation treatment of soft soil in freezing-thawing layer under freezing condition. The deformation characteristics of soft soil in freezing-thawing layer in Hulunbuir area in China are studied by using two compression test methods, namely, constant temperature and variable load (CTVL) test, variable temperature and variable load (VTVL) test. The compressibility indexes under different temperatures and consolidation pressures are obtained. The research shows that the freezing-thawing soft soil has large compressibility, the maximum strain of CTVL test is 19.89%, and the maximum compression of VTVL test can reach 18.16%. The results of CTVL compression tests show that when the soil temperature is in the range of severe phase change (-1.5℃-0℃), the temperature change has the greatest influence on the compression coefficient of soil. The result of VTVL compression test shows that some additional deformation occurs under the action of low temperature. The additional deformation is further increased when the soil is under high consolidation pressure and in the severe phase change (-1.5℃-0℃).

scholarly journals Deformation mechanisms of Mg-Ca-Zn alloys studied by means of micropillar compression tests

2021 ◽  
pp. 117151
Author(s):  
Jingya Wang ◽  
Yiwen Chen ◽  
Zhe Chen ◽  
Javier Llorca ◽  
Xiaoqin Zeng
Keyword(s):  
Deformation Mechanisms ◽  
Compression Tests ◽  
Micropillar Compression ◽  
Zn Alloys

scholarly journals Accounting for the Inhomogeneity of Deformation in Identification of Microstructure Evolution Model / Niejednorodność Odkształcenia W I Dentyfikacji Modelu Rozwoju Mikrostruktury

2015 ◽  
Vol 60 (4) ◽  
pp. 3087-3094 ◽  
Author(s):  
D. Szeliga ◽  
R. Kuziak ◽  
R. Kopp ◽  
G. Smyk ◽  
M. Pietrzyk
Keyword(s):  
Objective Function ◽  
Compression Test ◽  
Microstructure Evolution ◽  
Evolution Model ◽  
Second Step ◽  
Compression Tests ◽  
Force Measurements ◽  
Microstructural Parameters ◽  
Inverse Approach ◽  
Optimized Model

The paper deals with the problem of identification of microstructure evolution model on the basis of two-step compression test. Classical interpretation of this test assumes uniform fields of strains, stresses and temperatures in the deformation zone and calculates the coefficients in the model on the basis of force measurements in the second step. In the present paper the inverse approach was applied. Finite element (FE) simulations of the compression test were performed and local values of microstructural parameters were determined accounting for the inhomogeneity of deformation. Objective function was formulated as the Euclid norm for the error between measured and calculated forces for various interpass times. Coefficients in the microstructure evolution model were determined by searching for the minimum of the objective function. Optimized model was validated in simulations of plane strain compression tests.

Plastic Fluid Flow Parameters Identification Using a Simple Squeezing Test

2003 ◽  
Vol 13 (3) ◽  
pp. 132-141 ◽  
Author(s):  
Nicolas Roussel ◽  
Christophe Lanos
Keyword(s):  
Compression Test ◽  
Outer Part ◽  
Test Results ◽  
Compression Tests ◽  
Test Response ◽  
Flow Parameters ◽  
Plastic Fluid ◽  
Simple Compression ◽  
Fluid Behaviour ◽  
Theoretical Test

Abstract In this paper after a presentation of the compression test and its classical references in the rheological literature a behaviour parameter identification method is introduced using simple compression tests on concentrated geo-suspensions with a plastic fluid behaviour. The obtained theoretical test response is validated for several materials (natural soils, Kaolin clay …). It is also compared with previous solutions obtained by other authors to show that most existing solutions miss one or more terms. Elements are also given on two types of test response perturbations: the induced heterogeneity in the case of slow tests (consolidation phenomena) and the fragmentation of the outer part of sample (granular paste breakings). Finally, compression test results for a nano silica paste are presented as a example and treated as an application of the test exploitation method.

Experimental Investigation and Modelling of Claystone from Mae Moh Coal Mine, Thailand

2020 ◽  
Vol 841 ◽  
pp. 155-160
Author(s):  
Pongsakorn Wongchana ◽  
Peerapong Jitsangiam
Keyword(s):  
Stability Analysis ◽  
Slope Stability ◽  
Compression Test ◽  
Triaxial Compression ◽  
Slope Stability Analysis ◽  
Open Pit ◽  
Compression Tests ◽  
Coulomb Model ◽  
Mae Moh ◽  
Triaxial Compression Tests

The open pit mine is excavation soil from the Earth's surface, leading to presence of cut steep slopes with stability-concerned manners. Mae Moh open pit mine has the main component of claystone with ambiguous properties under stress condition changes from mine operations. Therefore, the strength of the claystone must be studied to be used for the slope stability analysis. Shear strength parameters for slope stability analysis were derived from the Triaxial Compression tests. Claystone is a type of sedimentary rock. Therefore, it is necessary to improve the equipment of the triaxial compression strength test to fit with intrinsic soft rock characteristics of the Mae Moh Claystone. Determination of parameters was based on Mohr Coulomb model, because it is the basis for slope stability analysis and can be resulted from the triaxial compression test. In addition, many computer-based programs for slope stability analysis also were relied onthe Mohr Coulomb model, including PLAXIS used in this study. Before the analysis, the model were validated by the function of “Simulation of Lab Test” in PLAXIS. Comparison on triaxial compression test results between the Mohr-Coulomb Model from PLAXIS and triaxial compression tests were made. This article reported the strength characteristics of Mae Moh claystone.

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