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.

MODELING AND SIMULATION OF DYNAMIC RECRYSTALLIZATION AND GRAIN GROWTH DURING HOT WORKING OF INCONEL 783 SUPERALLOY

2010 ◽  
Vol 17 (01) ◽  
pp. 105-109 ◽  
Author(s):  
JONG-TAEK YEOM ◽  
EUN JEOUNG JUNG ◽  
JEE HOON KIM ◽  
JEOUNG HAN KIM ◽  
JAE-KEUN HONG ◽  
...  
Keyword(s):  
Grain Growth ◽  
Compression Test ◽  
Microstructure Evolution ◽  
Optimization Technique ◽  
Hot Compression ◽  
Hot Working ◽  
Least Square ◽  
Isothermal Heat Treatment ◽  
Compression Tests ◽  
Hot Compression Test

In this study, the modeling of recrystallization and grain growth was investigated to predict the microstructure evolution during hot working of INCONEL 783 superalloy (Alloy 783). The recrystallization model was constructed on the basis of the Avrami formation. A least-square optimization technique was used to determine several important parameters within the model from isothermal heat treatment and hot compression test results. High temperature compression tests were carried out under different temperatures, strain rates and strain conditions. The model for describing the recrystallization and grain growth behaviors of Alloy 783 was implemented onto the user-subroutine of a commercial FE code. In order to demonstrate the reliability of the model, the microstructure evolution of Alloy 783 alloy during the hot compression test was simulated and was accorded well with the experimental results.

Effect of Deformation Parameters on Microstructure Evolution of Hot Deformed Superalloy GH4169

2015 ◽  
Vol 744-746 ◽  
pp. 1382-1385
Author(s):  
Tong He ◽  
Jing Hong Tuo ◽  
Zhi Hua Li ◽  
Qing An Tai
Keyword(s):  
Grain Size ◽  
Strain Rate ◽  
Microstructure Evolution ◽  
Temperature Increase ◽  
Compression Tests ◽  
Rate Decrease ◽  
Microstructural Parameters ◽  
Nickel Based Superalloy ◽  
Deformation Parameters ◽  
Recrystallized Grain Size

The evolution of the microstructure of a typical nickel-based superalloy GH4169 is investigated by the hot compression tests. The microstructural parameters such as fraction of recrystallization and grain size were analysed quantitatively. The results show that the effects of deforming temperature and strain rate on the dynamic recrystallized grain size are significant. With the deformed temperature increase and the strain rate decrease, the dynamic recrystallized grain size increases.

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

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.

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℃).

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.

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.

Microstructure Evolution of Hydrogenated Ti6Al4V Alloy during Compression

2012 ◽  
Vol 190-191 ◽  
pp. 517-521
Author(s):  
Bao Guo Yuan ◽  
Qiang Chen ◽  
Hai Ping Yu ◽  
Ping Li ◽  
Ke Min Xue ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Dislocation Density ◽  
Microstructure Evolution ◽  
Room Temperature ◽  
True Strain ◽  
True Stress ◽  
Compression Tests ◽  
Transmission Electron ◽  
Good Repeatability

Compression tests of the hydrogenated Ti6Al4V0.2H alloy were carried out using an Instron 5569 machine at room temperature. True stress-strain curves of the hydrogenated Ti6Al4V0.2H alloy under different compressive strains were obtained. Microstructure evolution of the hydrogenated Ti6Al4V0.2H alloy during the process of compression was investigated by optical microscopy and transmission electron microscopy. Results show that true stress-true strain curves of Ti6Al4V0.2H alloy have good repeatability. The deformation of grains, the dislocation density and slipping evolution during the process of compression are discussed.

Sign in / Sign up

Export Citation Format

Share Document