AZ31 Magnesium Alloy Parameters Identification through Inverse Analysis at 713 K

2012 ◽  
Vol 504-506 ◽  
pp. 643-646 ◽  
Author(s):  
Gillo Giuliano
Keyword(s):  
Strain Rate ◽  
Power Law ◽  
Inverse Analysis ◽  
Constant Pressure ◽  
Az31 Alloy ◽  
Equivalent Strain ◽  
Strain Rate Range ◽  
Displacement Curve ◽  
Material Constants ◽  
Equivalent Strain Rate

This paper introduces a fast and accurate procedure for determining the constants of magnesium AZ31 alloy at 713 K. The material behaviour is modelled by means of the power law relationship between the equivalent flow stress, the equivalent strain and the equivalent strain-rate within a narrow equivalent strain-rate range. Bulging tests were carried out in isothermal conditions (713 K) and at constant pressure in order to determine the material constants. It is necessary to evaluate the displacement and the thickness evolutions at the dome apex of the metal sheet. The time-displacement curve was obtained by laser measurements whereas a large number of bulging tests, interrupted at preset time intervals, were carried out to evaluate the thickness. The thickness was measured directly using a two-digit micrometer. The material constants, m, n and K were obtained in the power law relationship by means of constant pressure bulging tests coupled with the use of an inverse analysis technique. The results of comparison between experimental and numerical tests are shown and they indicate that the material constants can be accurately evaluated.

Applicability of power law for describing the rheology of soils of different origins and characteristics

2009 ◽  
Vol 46 (9) ◽  
pp. 1011-1023 ◽  
Author(s):  
Sueng Won Jeong ◽  
Serge Leroueil ◽  
Jacques Locat
Keyword(s):  
Strain Rate ◽  
Power Law ◽  
Debris Flows ◽  
Rheological Behaviour ◽  
Strain Rate Range ◽  
Rate Dependent ◽  
Different Origins ◽  
Power Law Index ◽  
Soil Behaviour ◽  
Low Activity

The rate-dependent rheological behaviour of soils of different origins and characteristics was studied and the applicability of the power law model was examined. The studied soils were divided into three groups: (i) low-activity soils, (ii) high-activity soils, and (iii) silt-rich soils. The results show that the power law applies to all these soils and is representative of soil behaviour in a strain rate range corresponding to debris flows, which is generally not the case with the Bingham model. For low-activity clays, the power law index, n, is typically equal to 0.12 and seems to increase with the plasticity index; it is larger (i.e., in the range of 0.2–0.6) for silt-rich soils. Comparison of n values for tests performed on intact and remoulded low-activity clay specimens indicates that the power law index is possibly strain-rate dependent.

Mathematical Modelling to Evaluate the Superplastic Material Constants by Bulge Test

2014 ◽  
Vol 607 ◽  
pp. 29-32
Author(s):  
Giuliano Gillo
Keyword(s):  
Mathematical Modelling ◽  
Experimental Tests ◽  
Limited Range ◽  
Equivalent Strain ◽  
Bulge Test ◽  
Strain Rates ◽  
Superplastic Material ◽  
Material Constants ◽  
Die Geometry ◽  
Equivalent Strain Rate

The mechanical behaviour of a superplastic material is often modelled by the power law relationship between the equivalent flow stress, the equivalent strain and the equivalent strain-rate at least over a limited range of strain rates. This paper introduces an original mathematical modelling to determine the superplastic material constants m, n and K by means of experimental tests carried out using a standard forming die geometry.

scholarly journals Modeling of the Strain Rate Dependency of Polycarbonate’s Yield Stress: Evaluation of Four Constitutive Equations

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Abdullah A. Al-Juaid ◽  
Ramzi Othman
Keyword(s):  
Experimental Data ◽  
Strain Rate ◽  
Yield Stress ◽  
Power Law ◽  
Constitutive Relations ◽  
Stress Sensitivity ◽  
Strain Rate Range ◽  
Rate Dependency ◽  
Rate Range ◽  
Strain Rate Dependency

The main focus of this paper is in evaluating four constitutive relations which model the strain rate dependency of polymers yield stress. Namely, the two-term power-law, the Ree-Eyring, the cooperative, and the newly modified-Eyring equations are used to fit tensile and compression yield stresses of polycarbonate, which are obtained from the literature. The four equations give good agreement with the experimental data. Despite using only three material constants, the modified-Eyring equation, which considers a strain rate-dependent activation volume, gives slightly worse fit than the three other equations. The two-term power-law and the cooperative equation predict a progressive increase in the strain rate sensitivity of the yield stress. Oppositely, the Ree-Eyring and the modified-Eyring equations show a clear transition between the low and high strain rate ranges. Namely, they predict a linear dependency of the yield stress in terms of the strain rate at the low strain rate range. Crossing a threshold strain rate, the yield stress sensitivity sharply increases as the strain rate increases. Hence, two different behaviors were observed though the four equations fit well the experimental data. More experimental data, mainly at the intermediate strain rate range, are needed to conclude which, of the two behaviors, is more appropriate for polymers.

Effect of Severe Caliber Rolling on Superplastic Properties of Mg-3Al-1Zn (AZ31) Alloy

2012 ◽  
Vol 735 ◽  
pp. 327-331 ◽  
Author(s):  
Rajendra Doiphode ◽  
Rahul Ramesh Kulkarni ◽  
S.V.S. Narayana Murty ◽  
Nityanand Prabhu ◽  
Bhagwati Prasad Kashyap
Keyword(s):  
Strain Rate ◽  
Constant Strain Rate ◽  
Material Constant ◽  
Az31 Alloy ◽  
Strain Rate Range ◽  
Constitutive Relationship ◽  
Grain Sizes ◽  
Different Temperatures ◽  
Rate Test ◽  
Superplastic Properties

Fine grains were developed in Mg-3Al-1Zn (AZ31) alloy by isothermal caliber rolling at five different temperatures in the range of 250-450°C. The samples of different grain sizes were deformed by constant strain rate and differential strain rate test techniques over the temperature range of 220-450 °C and strain rate range of 10-5 to 10-1 s-1. The effects of grain size, test temperature and strain rate on flow stSuperscSuperscript textript textress were analysed to develop the constitutive relationship for supSuperscript texterplastic deformation. The parameters of the constitutive relationship obtained from the constant strain rate tests and differential strain rate tests were used to find out the material constant A of the constitutive relationship.

scholarly journals An An Analysis of Strain Rate Distribution Using Streamline Model and A Quick Stop Device in Metal Cutting

2019 ◽  
Vol 22 (2) ◽  
pp. 136-142
Author(s):  
Osama Ali Kadhim ◽  
Fathi A. Alshamma
Keyword(s):  
Strain Rate ◽  
Chip Formation ◽  
Metal Cutting ◽  
Equivalent Strain ◽  
Element Analysis ◽  
Rate Distribution ◽  
Equivalent Strain Rate ◽  
Cumulative Plastic Strain ◽  
Cutting Speeds ◽  
Strain Rate Distribution

In this paper, a quick stop device technique and the streamline model were employed to study the chip formation in metal cutting. The behavior of chip deformation at the primary shear zone was described by this model. Orthogonal test of turning process over a workpiece of the 6061-T6 aluminum alloy at different cutting speeds was carried out. The results of the equivalent strain rate and cumulative plastic strain were used to describe the complexity of chip formation. Finite element analysis by ABAQUS/explicit package was also employed to verify the streamline model. Some behavior of formation and strain rate distribution differs from the experimental results, but the overall trend and maximum results are approximately close. In addition, the quick stop device technique is described in detail. Which could be used in other kinds of studies, such as the metallurgical observation.

Development of a Material Constitutive for High-Rate Using a Combined Experiment/Computation Method

2004 ◽  
Vol 261-263 ◽  
pp. 269-276
Author(s):  
J.F. Lu ◽  
Zhuo Zhuang ◽  
K. Shimamura
Keyword(s):  
Strain Rate ◽  
Split Hopkinson Pressure Bar ◽  
Equivalent Strain ◽  
High Rate ◽  
Computation Method ◽  
Failure Behavior ◽  
Hopkinson Pressure Bar ◽  
Material Constants ◽  
Split Hopkinson ◽  
Pressure Bar

To describe the high-rate behaviour of metals, a revised form of the classic Johnson-Cook strength model with unknown material constants has been used. The 1D stress-strain relations as well as the effects of strain, strain rate and temperature are examined by Split Hopkinson Pressure Bar (SHPB) test. The undetermined material constants are solved using a variable-dissociation method. The element failure criterion based on maximum equivalent strain is also introduced to estimate the material failure behavior under high strain rate. A corresponding user-defined material subroutine (UMAT) has been developed for revised Johnson-Cook model, which is implemented into ABAQUS. Using this implicit scheme, several groups of finite element simulations under different strain rates are completed in ABAQUS/Standard. The results agree well with the test data and other results by explicit code.

scholarly journals On the strain-rate sensitivity of columnar ice

1997 ◽  
Vol 43 (145) ◽  
pp. 408-410 ◽  
Author(s):  
M. E. Manley ◽  
E. M. Schulson
Keyword(s):  
Strain Rate ◽  
Power Law ◽  
Rate Sensitivity ◽  
Dislocation Climb ◽  
Stress And Strain ◽  
Displacement Curve ◽  
Power Law Exponent ◽  
Basal Dislocation ◽  
Image Position ◽  
Stress And Strain Rate

AbstractA power law relation between stress and strain rate of the formwas used to describe the response to strain rate of S1 ice loaded across the columns at –10° C. The rate exponent,n, decreased with increasing strain from about 4.6 at an observed peak on the load displacement curve to approximately 2.6 at a shortening of 2%. Analysis of these results and of the results of other authors on different forms of ice deformed at the same temperature suggests that the power law exponent,nis proportional toFc/FgThe parameterFc/Fgis the far-field basal dislocation climb force divided by the glide force.

The Research and Optimization of a 6061 Aluminum Rectangular Tube Extrusion Using Porthole Dies According to the Parameter of Split Ratio

2012 ◽  
Vol 268-270 ◽  
pp. 391-395
Author(s):  
Shu Mei Lou ◽  
Guo Liang Xing ◽  
Sheng Xue Qin ◽  
Lin Jing Xiao
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Strain Rate ◽  
Equivalent Strain ◽  
Tube Extrusion ◽  
Split Ratio ◽  
Die Structure ◽  
Rectangular Tube ◽  
Equivalent Strain Rate ◽  
Deform 3D

Extrusions of a 6061 aluminum rectangular tube using porthole dies with three assigned different split ratios were simulated by the software DEFORM-3D based on Finite element method. The distributions of stress, equivalent strain rate, temperature, velocity of the deformation materials and the mold stress during the three extrusion processes were obtained, respectively. By analyzing the distributions of those fields, the most reasonable split ratio is selected and then the die structure is modified.

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