scholarly journals Plastometric tests for plasticine as physical modelling material

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Łukasz Wójcik ◽  
Konrad Lis ◽  
Zbigniew Pater
Keyword(s):  
Strain Rate ◽  
Temperature Change ◽  
Compression Test ◽  
Constitutive Equations ◽  
Metal Forming ◽  
Material Flow ◽  
Physical Modelling ◽  
Flow Curves ◽  
Black And White ◽  
White Colour

Abstract This paper presents results of plastometric tests for plasticine, used as material for physical modelling of metal forming processes. The test was conducted by means of compressing by flat dies of cylindrical billets at various temperatures. The aim of the conducted research was comparison of yield stresses and course of material flow curves. Tests were made for plasticine in black and white colour. On the basis of the obtained experimental results, the influence of forming parameters change on flow curves course was determined. Sensitivity of yield stresses change in function of material deformation, caused by forging temperature change within the scope of 0&C ÷ 20&C and differentiation of strain rate for ˙ɛ = 0.563; ˙ɛ = 0.0563; ˙ɛ = 0.0056s−1,was evaluated. Experimental curves obtained in compression test were described by constitutive equations. On the basis of the obtained results the function which most favourably describes flow curves was chosen.

Formability of Explosive Welded Mg/Al Bimetallic Bar

2016 ◽  
Vol 716 ◽  
pp. 114-120 ◽  
Author(s):  
Sebastian Mróz ◽  
Piotr Szota ◽  
Teresa Bajor ◽  
Andrzej Stefanik
Keyword(s):  
Plastic Deformation ◽  
Strain Rate ◽  
Process Parameters ◽  
Metal Forming ◽  
Explosive Welding ◽  
Physical Modelling ◽  
Main Process ◽  
Compression Tests ◽  
Welding Method

The paper presents the results of physical modelling of the plastic deformation of the Mg/Al bimetallic specimens using the Gleeble 3800 simulator. The plastic deformation of Mg/Al bimetal specimens characterized by the diameter to thickness ratio equal to 1 was tested in compression tests. The aim of this work was determination of the range of parameters as temperature and strain rate that mainly influence on the plastic deformation of Mg/Al bars during metal forming processes. The tests were carried out for temperature range from 300 to 400°C for different strain rate values. The stock was round 22.5 mm-diameter with an Al layer share of 28% Mg/Al bars that had been produced using the explosive welding method. Based on the analysis of the obtained testing results it has been found that one of the main process parameters influencing the plastic deformation the bimetal components is the initial stock temperature and strain rate values.

Investigation on Hardening and Softening Behavior of Steel after Rapid Strain Rate Changes

2016 ◽  
Vol 716 ◽  
pp. 121-128 ◽  
Author(s):  
Jens Dierdorf ◽  
Johannes Lohmar ◽  
Gerhard Hirt
Keyword(s):  
Flow Stress ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Metal Forming ◽  
Elevated Temperatures ◽  
Relaxation Behavior ◽  
Rate Change ◽  
Strain Rates ◽  
Flow Curves ◽  
Strain Rate Change

The design of industrial hot metal forming processes nowadays is mostly carried out using commercial Finite Element (FE) software codes. For precise FE simulations, reliable material properties are a crucial factor. In bulk metal forming, the most important material property is the materials flow stress, which determines the form filling and the necessary forming forces. At elevated temperatures, the flow stress of steels is determined by strain hardening, dynamic recovery and partly by dynamic recrystallization, which is dependent on strain rate and temperature. To simulate hot forming processes, which are often characterized by rapidly changing strain rates and temperatures, the flow stress is typically derived from flow curves, determined at arbitrary constant temperatures and strain rates only via linear interpolation. Hence, the materials instant reaction and relaxation behavior caused by rapid strain rate changes is not captured during simulation. To investigate the relevance of the relaxation behavior for FE simulations, trails with abrupt strain rate change are laid out and the effect on the material flow stress is analyzed in this paper. Additionally, the microstructure evolution due to the strain rate change is investigated. For this purpose, cylinder compression tests of an industrial case hardening steel are conducted at elevated temperatures and different strain rates. To analyze the influence of rapid strain rate changes, changes by one power of ten are performed at a strain of 0.3. As a reference, flow curves of the same material are determined at the initial and final constant strain rate. To investigate the microstructure evolution, compression samples are quenched at different stages, before and after the strain rate change. The results show that the flow curves after the strain rate change tend to approximate the flow curves measured for the final strain rate. However, directly after the strain rate change significant differences between the assumed instant flow stress and the real material behavior can be observed. Furthermore, it can be shown that the state of dynamic recrystallization at the time of the strain rate change influences the material response and relaxation behavior resulting in different slopes of the investigated flow curves after the strain rate change.

Validation and application of a screw method for strain measurement in bulk metal forming

2007 ◽  
Vol 42 (7) ◽  
pp. 519-527 ◽  
Author(s):  
S J Yuan ◽  
J Zhang ◽  
Z. B He
Keyword(s):  
Numerical Simulation ◽  
Plastic Strain ◽  
Metal Forming ◽  
Material Flow ◽  
Physical Modelling ◽  
Material Model ◽  
Processing Parameters ◽  
Bulk Metal ◽  
Bulk Metal Forming ◽  
Numerical Simulation Methods

A new method for measurement of plastic strain inside a deforming body is advanced and validated through a simple cylinder upsetting experiment. It is also applied to a ring for demonstrating this method in a ring compression test. The experimental results and numerical simulation show good agreement. In contrast with other physical modelling methods, this method utilizes the real metal for a sensor and workpiece, rather than using substitute materials, and can observe and measure material flow and plastic strain inside the specimen without splitting it before deformation. It can be used to study material flow and to predict strain distribution in general bulk metal-forming processes such as upsetting, extrusion, and die forging. It is also useful for verification of the numerical simulation methods when the material model and the processing parameters were uncertain and/or not easily verified.

Hot Deformation Characteristics of Spray Formed Nickel Based P/M Superalloy

2014 ◽  
Vol 788 ◽  
pp. 565-568
Author(s):  
Na Liu ◽  
Z. Li ◽  
G.Q. Zhang ◽  
H. Yuan ◽  
W.Y. Xu ◽  
...  
Keyword(s):  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Compression Test ◽  
Hot Deformation ◽  
Deformation Temperature ◽  
True Strain ◽  
Spray Forming ◽  
Solution Temperature ◽  
Flow Curves ◽  
Gleeble 3500

The hot deformation behavior of a nickel based P/M superalloy by spray forming and hot isostaticpressingwas investigated by isothermal compression test at Gleeble 3500 thermal mechanical simulator. The compression test was performed in the temperature ranging from 1025°C to 1150°C and in the strain rate ranging from 10-1/s to 10-3/s. The results show that the flow curves of true stress and true strain exhibit typical dynamic recrystallization and dynamic recovery. Compression temperature and strain rate have a strong effect on the dynamic recrystallization grain refinement.With higher strain rate the refined dynamic recrystallizationmicrostructure can be obtained at deformation temperature lower thanγ′solution temperature. Grain coarsening occurs at the deformation temperature close to γ′solution temperature, and the grain grows up obviously with decreasing strain rate.

scholarly journals The Behavior of Melts with Vanishing Viscosity in the Cone-and-Plate Rheometer

2019 ◽  
Vol 10 (1) ◽  
pp. 172
Author(s):  
Lihui Lang ◽  
Sergei Alexandrov ◽  
Elena Lyamina ◽  
Van Manh Dinh
Keyword(s):  
Strain Rate ◽  
Shear Strain ◽  
Constitutive Equations ◽  
Material Flow ◽  
Analytic Solution ◽  
Theoretical Solution ◽  
Qualitative Behavior ◽  
Strain Rate Tensor ◽  
Shear Strain Rate ◽  
Vanishing Viscosity

A semi-analytic solution for material flow in the cone-and-plate rheometer is presented. It is assumed that the viscosity is solely a function of the second invariant of the strain rate tensor. A distinguishing feature of the constitutive equations used is that the viscosity is vanishing as the shear strain rate approaches infinity. This feature of the constitutive equations affects the qualitative behavior of the solution. Asymptotic analysis is carried out near the surface of the cone to reveal these features. It is shown that the regime of sliding must occur and the shear strain rate approaches infinity under certain conditions. It is also shown that the asymptotic behavior of the viscosity as the shear strain rate approaches infinity controls these qualitative features of the theoretical solution. Some of these features are feasible for experimental verification. An interpretation of the theoretical solution found is proposed.

scholarly journals Possibilities of Using Physical Modeling With Soft Materials to Analyze and Optimize Metal Forming Processes

2020 ◽  
Author(s):  
Marek Hawryluk ◽  
Maciej Suliga ◽  
Mateusz Więclaw
Keyword(s):  
Numerical Modelling ◽  
Metal Forming ◽  
Material Flow ◽  
Physical Simulation ◽  
Dead Zone ◽  
Physical Modelling ◽  
Soft Materials ◽  
Extrusion Process ◽  
Model Material ◽  
Real Process

Abstract The study presents the concept of physical modelling together with the characterization of the modelling materials as well as the possibilities of applying this type of physical simulation methods for the analysis, design and optimization of industrial metal forming processes. The paper discusses the crucial similarity conditions between the physical model and the real process necessary to transform the results into industrial processes. Physical modelling is one of the most popular as well as cheapest methods of analyzing metal plastic forming processes and it can constitute an easy independent verifying tool. It can also be a competitive alternative or supplementation, or a quick verification, of the popular yet relatively expensive methods based on a broadly understood mathematical apparatus, e.g. the finite element method or various types of computer science techniques. The method provides the possibility to define the stress and deformation distribution, estimate the force parameters of the given process as well as localize the dead zones and material flow errors. On the example of a forward extrusion process, the study demonstrates the effect of matching the model material to two metallic materials: annealed aluminum and reinforced aluminum. Additionally, for reinforced aluminum, numerical modelling was performed, which made it possible to determine e.g.: the force parameters and the material flow manner. Next, based on physical modelling, verification through numerical modelling was made of the boundary and tribological conditions, as physical modelling revealed a so-called dead zone in the corner of the die, which had not been recorded in numerical modelling.

scholarly journals Physical Modelling of Metal Forming of Bars Made of Magnesium Alloys (AZ61) / Fizyczne Modelowanie Warunków Przeróbki Plastycznej Prętów Ze Stopów Magnezu (AZ61)

2015 ◽  
Vol 60 (4) ◽  
pp. 3007-3010
Author(s):  
T. Bajor ◽  
H. Dyja ◽  
K. Laber
Keyword(s):  
Magnesium Alloy ◽  
Strain Rate ◽  
Yield Stress ◽  
Magnesium Alloys ◽  
Research Methodology ◽  
Metal Forming ◽  
Physical Modelling ◽  
Testing System ◽  
Different Temperatures ◽  
Metallurgical Processes

This study presents the results of physical modelling of the processes of metal forming of bars made of magnesium alloy (AZ61) obtained using two research methodologies. The study employed the Gleeble 3800 testing system for simulation of metallurgical processes and a torsion plastometer. Depending on the research methodology used, the examinations were carried out in the temperature range of 200 ÷ 400°C and strain rate of (0.1 - 10 s-1). The results obtained in the study were used to determine the value of yield stress for AZ61 alloy for different strain procedures and different temperatures and strain ratios.

Fundamental investigations on the material flow at combined sheet and bulk metal forming processes

CIRP Annals ◽  
2011 ◽  
Vol 60 (1) ◽  
pp. 283-286 ◽  
Author(s):  
M. Merklein ◽  
J. Koch ◽  
S. Opel ◽  
T. Schneider
Keyword(s):  
Metal Forming ◽  
Material Flow ◽  
Bulk Metal ◽  
Bulk Metal Forming

Eulerian FEA With Volume of Solid (VOS) Application in Metal Forming

2010 ◽  
Author(s):  
K. S. Al-Athel ◽  
M. S. Gadala
Keyword(s):  
Finite Element ◽  
Free Surface ◽  
Process Improvement ◽  
Metal Forming ◽  
Material Flow ◽  
Solid Mechanics ◽  
Uniform Mesh ◽  
Element Formulation ◽  
Volume Of Fluid Method ◽  
Whole Process

The adaptation of the volume of fluid method (VOF) to solid mechanics (VOS) is presented in this work with the focus on metal forming applications. The method is discussed for a general non-uniform mesh with Eulerian finite element formulation. The implementation of the VOS method in metal forming applications is presented by focusing on topics such as the contact between the tool and the workpiece, tracking of the free surface of the material flow and the connectivity of the free surface during the whole process. Improvement on the connectivity of the free surface and the representation of curves is achieved by considering the mechanics of different metal forming processes. Different applications are simulated and discussed to highlight the capability of the VOS method.

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