A Time-Dependent Material Model for the Simulation of Hot Gas-Pressure Forming of Magnesium Alloy AZ31

2012 ◽  
Vol 735 ◽  
pp. 198-203 ◽  
Author(s):  
Alexander J. Carpenter ◽  
Eric M. Taleff ◽  
Louis G. Hector ◽  
Jon T. Carter ◽  
Paul E. Krajewski
Keyword(s):  
Experimental Data ◽  
Sheet Material ◽  
Material Model ◽  
Gas Pressure ◽  
Time Dependent ◽  
Dome Height ◽  
Fem Simulations ◽  
Hot Gas ◽  
Magnesium Alloy Az31 ◽  
Az31 Sheet

A time-dependent material constitutive model is developed for the deformation of wrought Mg AZ31 sheet material at 450°C. This material model is used to simulate gas-pressure bulge forming of AZ31 sheet into hemispherical domes. Finite-element-method (FEM) simulations using this material model are compared against experimental data obtained for dome height as a function of forming time under forming conditions identical to those assumed in the simulations. The time-dependent material model predicts experimental dome heights during forming with a quite useful accuracy. The most significant advantage of the time-dependent material model is that it can address the effect of preheating time on forming. Preheating times shorter than ~120 s produce an increase in forming rate. This material model provides a quantitative means of accounting for that effect.

Comparison of Three Material Models to Predict the Time-Dependent Deformation of a Single Cell Under Micropipette Aspiration

2008 ◽  
Author(s):  
Ruogang Zhao ◽  
Kristine Wyss ◽  
Craig A. Simmons
Keyword(s):  
Experimental Data ◽  
Large Strain ◽  
Single Cells ◽  
Material Model ◽  
Micropipette Aspiration ◽  
Time Dependent ◽  
Large Strains ◽  
Fe Model ◽  
Whole Cells ◽  
Model Combining

Micropipette aspiration is an experimental technique that is used widely to measure the mechanical properties of single cells [1]. The viscoelastic properties of the probed cell are often estimated by fitting experimental data to a three-parameter standard linear solid (SLS) half-space model (e.g., [1]). However, this analytical model does not account for the large strains that can occur with micropipette aspiration. This limitation has motivated the development of numerical methods to interpret the experimental data. For example, Zhou [2] implemented a material model combining a hyperelastic neo-Hookean material and a viscoelastic SLS material in an axisymmetric finite element (FE) model to simulate large strain micropipette aspiration of a suspended cell. The time-dependent creep deformation of cells has also been described by power-law rheology [3]; this material model has been applied to micropipette aspiration of nuclei [4], but not whole cells.

Local Thinning at a Die Entry Radius During Hot Gas-Pressure Forming of an AA5083 Sheet

2010 ◽  
Vol 132 (1) ◽  
Author(s):  
Eric M. Taleff ◽  
Louis G. Hector ◽  
John R. Bradley ◽  
Ravi Verma ◽  
Paul E. Krajewski
Keyword(s):  
Sheet Material ◽  
Sheet Thickness ◽  
Gas Pressure ◽  
Die Geometry ◽  
Fine Grained ◽  
Hot Gas ◽  
Element Simulation ◽  
Mechanism Of Failure ◽  
The Relationship ◽  
Lubrication Conditions

Splitting at regions of local thinning below die entry radii is a critically important mechanism of failure in hot gas-pressure forming of sheet materials. Local thinning is controlled by sheet-die friction and die geometry, as well as sheet material properties. In this study, local thinning is investigated at a particularly severe die entry radius during hot forming of a fine-grained AA5083 sheet at 450°C. Particular emphasis is placed on the relationship between local thinning and sheet-die friction conditions. A simple analysis of the mechanics of this thinning phenomenon is presented. Finite element simulation results are presented for different sheet-die friction conditions. Sheet thickness profiles measured from parts produced in forming experiments using three different lubrication conditions are compared with predictions from simulations. Simulation predictions agree well with experimental data for the occurrence and location of thinning below a die entry radius. Additional insights into sheet-die friction for controlling local thinning and preventing premature necking failure are detailed.

A mechanism-dependent material model for the effects of grain growth and anisotropy on plastic deformation of magnesium alloy AZ31 sheet at 450°C

2014 ◽  
Vol 68 ◽  
pp. 254-266 ◽  
Author(s):  
Alexander J. Carpenter ◽  
Aravindha R. Antoniswamy ◽  
Jon T. Carter ◽  
Louis G. Hector ◽  
Eric M. Taleff
Keyword(s):  
Plastic Deformation ◽  
Magnesium Alloy ◽  
Grain Growth ◽  
Material Model ◽  
Alloy Az31 ◽  
Magnesium Alloy Az31 ◽  
Az31 Sheet

Diagnostics of metal samples using the results of experimental and theoretical study of positively charged microparticles formed upon sample destruction

2018 ◽  
Vol 84 (10) ◽  
pp. 23-28
Author(s):  
D. A. Golentsov ◽  
A. G. Gulin ◽  
Vladimir A. Likhter ◽  
K. E. Ulybyshev
Keyword(s):  
Experimental Data ◽  
Early Stage ◽  
Experimental Studies ◽  
Material Model ◽  
Total Charge ◽  
Cross Sectional ◽  
Practical Applications ◽  
Mechanical And Electrical Properties ◽  
Order Of Magnitude ◽  
Using Data

Destruction of bodies is accompanied by formation of both large and microscopic fragments. Numerous experiments on the rupture of different samples show that those fragments carry a positive electric charge. his phenomenon is of interest from the viewpoint of its potential application to contactless diagnostics of the early stage of destruction of the elements in various technical devices. However, the lack of understanding the nature of this phenomenon restricts the possibility of its practical applications. Experimental studies were carried out using an apparatus that allowed direct measurements of the total charge of the microparticles formed upon sample rupture and determination of their size and quantity. The results of rupture tests of duralumin and electrical steel showed that the size of microparticles is several tens of microns, the particle charge per particle is on the order of 10–14 C, and their amount can be estimated as the ratio of the cross-sectional area of the sample at the point of discontinuity to the square of the microparticle size. A model of charge formation on the microparticles is developed proceeding from the experimental data and current concept of the electron gas in metals. The model makes it possible to determine the charge of the microparticle using data on the particle size and mechanical and electrical properties of the material. Model estimates of the total charge of particles show order-of-magnitude agreement with the experimental data.

scholarly journals Investigation of the Thickness Differential on the Formability of Aluminum Tailor Welded Blanks

Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 875
Author(s):  
Jie Wu ◽  
Yuri Hovanski ◽  
Michael Miles
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Numerical Model ◽  
Plastic Strain ◽  
Finite Element Model ◽  
Equivalent Plastic Strain ◽  
Element Model ◽  
Dome Height ◽  
Tailor Welded Blanks ◽  
Simulation Results

A finite element model is proposed to investigate the effect of thickness differential on Limiting Dome Height (LDH) testing of aluminum tailor-welded blanks. The numerical model is validated via comparison of the equivalent plastic strain and displacement distribution between the simulation results and the experimental data. The normalized equivalent plastic strain and normalized LDH values are proposed as a means of quantifying the influence of thickness differential for a variety of different ratios. Increasing thickness differential was found to decrease the normalized equivalent plastic strain and normalized LDH values, this providing an evaluation of blank formability.

Modal Analysis of the Axial Compressor Blade: Advanced Time-Dependent Electronic Interferometry and Finite Element Method

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Mykhaylo Tkach ◽  
Serhii Morhun ◽  
Yuri Zolotoy ◽  
Irina Zhuk
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Finite Element ◽  
High Reliability ◽  
Axial Compressor ◽  
Time Dependent ◽  
Experimental Setup ◽  
Vibration Modes ◽  
Compressor Blades ◽  
Isoparametric Finite Element

AbstractNatural frequencies and vibration modes of axial compressor blades are investigated. A refined mathematical model based on the usage of an eight-nodal curvilinear isoparametric finite element was applied. The verification of the model is carried out by finding the frequencies and vibration modes of a smooth cylindrical shell and comparing them with experimental data. A high-precision experimental setup based on an advanced method of time-dependent electronic interferometry was developed for this aim. Thus, the objective of the study is to verify the adequacy of the refined mathematical model by means of the advanced time-dependent electronic interferometry experimental method. The divergence of the results of frequency measurements between numerical calculations and experimental data does not exceed 5 % that indicates the adequacy and high reliability of the developed mathematical model. The developed mathematical model and experimental setup can be used later in the study of blades with more complex geometric and strength characteristics or in cases when the real boundary conditions or mechanical characteristics of material are uncertain.

Improvement in Mechanical Properties of Magnesium Alloy (AZ31) Sheet Fabricated by Casting and Subsequent Plastic Working

2003 ◽  
Vol 439 ◽  
pp. 227-232
Author(s):  
Jae Wan Song ◽  
Chang Won Kim ◽  
Jeong Whan Han ◽  
Mok Soon Kim ◽  
Sun Keun Hwang
Keyword(s):  
Mechanical Properties ◽  
Magnesium Alloy ◽  
Plastic Working ◽  
Alloy Az31 ◽  
Magnesium Alloy Az31 ◽  
Az31 Sheet

A Single Technically Consistent Design Formula for the Thickness of Cylindrical Sections Under Internal Pressure

2006 ◽  
Vol 129 (1) ◽  
pp. 211-215 ◽  
Author(s):  
John D. Fishburn
Keyword(s):  
Experimental Data ◽  
Internal Pressure ◽  
State Of The Art ◽  
Original Data ◽  
Pressure Vessels ◽  
Time Dependent ◽  
Design Codes ◽  
Recent Developments ◽  
Current Design ◽  
Single Formula

Within the current design codes for boilers, piping, and pressure vessels, there are many different equations for the thickness of a cylindrical section under internal pressure. A reassessment of these various formulations, using the original data, is described together with more recent developments in the state of the art. A single formula, which can be demonstrated to retain the same design margin in both the time-dependent and time-independent regimes, is shown to give the best correlation with the experimental data and is proposed for consideration for inclusion in the design codes.

TEMPERATURE-DEPENDENCE OF PROTON CONDUCTIVITY IN HYDROGEN-BONDED MOLECULAR SYSTEMS

2007 ◽  
Vol 21 (19) ◽  
pp. 1239-1252 ◽  
Author(s):  
XIAO-FENG PANG ◽  
BO DENG ◽  
HUAI-WU ZHANG ◽  
YUAN-PING FENG
Keyword(s):  
Experimental Data ◽  
Electric Field ◽  
Temperature Dependence ◽  
Electric Conductivity ◽  
Proton Conductivity ◽  
Model System ◽  
Time Dependent ◽  
Molecular Systems ◽  
Damping Effect ◽  
Hydrogen Bonded

The temperature-dependence of proton electric conductivity in hydrogen-bonded molecular systems with damping effect was studied. The time-dependent velocity of proton and its mobility are determined from the Hamiltonian of a model system. The calculated mobility of (3.57–3.76) × 10-6 m 2/ Vs for uniform ice is in agreement with the experimental value of (1 - 10) × 10-2 m 2/ Vs . When the temperature and damping effects of the medium are considered, the mobility is found to depend on the temperature for various electric field values in the system, i.e. the mobility increases initially and reaches a maximum at about 191 K, but decreases subsequently to a minimum at approximately 241 K, and increases again in the range of 150–270 K. This behavior agrees with experimental data of ice.

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