scholarly journals Analysis of Deformation and Prediction of Cracks in the Cogging Process for Die Steel at Elevated Temperatures

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5589
Author(s):  
Marcin Kukuryk
Keyword(s):  
Elevated Temperatures ◽  
Metal Flow ◽  
Three Dimensional ◽  
Internal Layers ◽  
The Finite Element Method ◽  
Damage Factor ◽  
Die Steel ◽  
Ductile Fractures ◽  
Thermal Phenomena ◽  
Good Agreement

In this paper, an analysis of a three-dimensional state of strain and stress in the case of the hot cogging process of X32CrMoV12-28 die steel with the application of the finite element method is presented. The results of the investigations connected with the simulation of the kinematics of metal flow and thermal phenomena are presented, accompanied by prognosing the formation of ductile fractures in the course of the hot cogging process conducted with the application of three different shape tools and of a proposed deformation criterion of the loss of cohesion. The applied anvils were found to be highly effective in the aspects of distribution of effective strains and stresses, absence of tensile stresses in the axial zones of a forging, and also of a significant thermal stability in the internal layers of a deformed material. The developed course of changes in the deformation of the damage factor in the case of forging in the investigated anvils renders it possible to predict the situation and the phase of deformation in which the loss of cohesion by a deformed material will occur. The comparison between the predicted and the experimental results showed a good agreement.

scholarly journals Analysis Of Deformation And Microstructural Evolution In The Hot Forgingof The Ti-6Al-4V Alloy

2015 ◽  
Vol 60 (3) ◽  
pp. 1639-1648 ◽  
Author(s):  
M. Kukuryk
Keyword(s):  
Effective Strain ◽  
Metal Flow ◽  
Three Dimensional ◽  
Test Results ◽  
The Finite Element Method ◽  
Rigid Plastic ◽  
Microstructure Parameters ◽  
Thermal Phenomena ◽  
Tool Types

Abstract The paper presents the analysis of the three-dimensional strain state for the cogging process of the Ti-6Al-4V alloy using the finite element method, assuming the rigid-plastic model of the deformed body. It reports the results of simulation studies on the metal flow pattern and thermal phenomena occurring in the hot cogging process conducted on three tool types. The computation results enable the determination of the distribution of effective strain, effective stress, mean stress and temperature within the volume of the blank. This solution has been complemented by adding the model of microstructure evolution during the cogging process. The numerical analysis was made using the DEFORM-3D consisting of a mechanical, a thermal and a microstructural parts. The comparison of the theoretical study and experimental test results indicates a potential for the developed model to be employed for predicting deformations and microstructure parameters.

scholarly journals In-Depth Verification of a Numerical Model for an Axisymmetric RC Dome

Symmetry ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 2152
Author(s):  
Przemysław Czumaj ◽  
Sławomir Dudziak ◽  
Zbigniew Kacprzyk
Keyword(s):  
Three Dimensional ◽  
Spatial Models ◽  
Detailed Comparison ◽  
The Finite Element Method ◽  
Robot System ◽  
Engineering Structures ◽  
Computational Analyses ◽  
Computational Systems ◽  
Good Agreement ◽  
Made In

The designers of civil engineering structures often have to face the problem of the reliability of complex computational analyses performed most often with the Finite Element Method (FEM). Any assessment of reliability of such analyses is difficult and can only be approximate. The present paper puts forward a new method of verification and validation of the structural analyses upon an illustrative example of a dome strengthened by circumferential ribs along the upper and lower edges. Four computational systems were used, namely Abaqus, Autodesk Robot, Dlubal RFEM, and FEAS. Different models were also analyzed—two-dimensional (2D) and three-dimensional (3D) ones using continuum, bar, and shell finite elements. The results of the static (with two kinds of load—self-weight and load distributed along the upper ring) and modal analyses are presented. A detailed comparison between the systems’ and models’ predictions was made. In general, the spatial models predicted a less stiff behavior of the analyzed dome than the planar models. The good agreement between different models and systems was obtained for the first natural frequency with axisymmetric eigenmodes (except from the Autodesk Robot system). The presented approach to the verification of complex shell–bar models can be effectively applied by structural designers.

Dynamic stress analysis of rotating twisted and tapered blades

1980 ◽  
Vol 15 (3) ◽  
pp. 117-126 ◽  
Author(s):  
V Ramamurti ◽  
S Sreenivasamurthy
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Stress Analysis ◽  
Dynamic Stress ◽  
Three Dimensional ◽  
The Finite Element Method ◽  
Extensive Analysis ◽  
Dynamic Stress Analysis ◽  
Skew Angles ◽  
Good Agreement

In this paper the finite element method has been used to determine the stresses and deformations of pre-twisted and tapered blades. Three-dimensional, twenty-noded isoparametric elements have been used for the analysis. Extensive analysis has been done for various pre-twist angles, skew angles, breadth to length ratios, and breadth to thickness ratios of the blades. Experiments were carried out to determine the stresses for the verification of the numerical results and they were found to be in good agreement.

scholarly journals Numerical Modelling of the Three-Dimensional Slamming Problem

2002 ◽  
Author(s):  
Matthieu Tourbier ◽  
Bernard Peseux ◽  
Bundi Donguy ◽  
Laurent Gornet
Keyword(s):  
Finite Element Method ◽  
Experimental Investigation ◽  
Thickness Distribution ◽  
Three Dimensional ◽  
Free Fall ◽  
The Finite Element Method ◽  
Hydrodynamic Problem ◽  
In Series ◽  
Drop Tests ◽  
Good Agreement

This paper deals with the slamming phenomenon for deformable structures. In a first part, a three-dimensional hydrodynamic problem is solved numerically with the Finite Element Method. The results for a rigid body are successfully compared to the analytical solutions. After the numerical analysis, an experimental investigation is presented. It consists in series of free fall drop-tests of rigid, deformable cones shaped models with different deadrise angle and thickness. Distribution of the pressure and its evolution are analyzed. Numerical and experimental results are compared and present good agreement.

scholarly journals Analysis Of Deformation And Microstructural Evolution In The Hot Forging Of The Ti-6Al-4V Alloy

2015 ◽  
Vol 60 (2) ◽  
pp. 597-604 ◽  
Author(s):  
M. Kukuryk
Keyword(s):  
Effective Strain ◽  
Metal Flow ◽  
Hot Forging ◽  
Three Dimensional ◽  
Test Results ◽  
Rigid Plastic ◽  
Microstructure Parameters ◽  
Thermal Phenomena ◽  
Tool Types

Abstract The paper presents the analysis of the three-dimensional strain state for the cogging process of the Ti-6Al-4V alloy using the finite element method, assuming the rigid-plastic model of the deformed body. It reports the results of simulation studies on the metal flow pattern and thermal phenomena occurring in the hot cogging process conducted on three tool types. The computation results enable the determination of the distribution of effective strain, effective stress, mean stress and temperature within the volume of the blank. This solution has been complemented by adding the model of microstructure evolution during the cogging process. The numerical analysis was made using the DEFORM-3D consisting of a mechanical, a thermal and a microstructural parts. The comparison of the theoretical study and experimental test results indicates a potential for the developed model to be employed for predicting deformations and microstructure parameters.

scholarly journals Charge transport mechanism in dielectrics: drift and diffusion of trapped charge carriers

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Andrey A. Pil’nik ◽  
Andrey A. Chernov ◽  
Damir R. Islamov
Keyword(s):  
Charge Transport ◽  
Three Dimensional ◽  
Continuum Theory ◽  
Theoretical Models ◽  
Charge Carriers ◽  
The Finite Element Method ◽  
Drift Current ◽  
And Diffusion ◽  
Good Agreement ◽  
Trapped Charge

Abstract In this study, we developed a continuum theory of the charge transport in dielectrics by trapped electrons and holes, which takes into account two separate contributions of the current of trapped charge carriers: the drift part and the diffusion one. It was shown that drift current is mostly dominant in the bulk, while the diffusion one reaches significant values near contacts. A comparison with other theoretical models and experiments shows a good agreement. The model can be extended to two- and three-dimensional systems. The developed model, formulated in partial differential equations, can be numerically implemented in the finite element method code.

Three-Dimensional Problems

1989 ◽  
Author(s):  
Shiro Kobayashi ◽  
Soo-Ik Oh ◽  
Taylan Altan
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Metal Flow ◽  
Three Dimensional ◽  
The Finite Element Method ◽  
Upper Bound Method ◽  
Admissible Velocity ◽  
Brick Element ◽  
Flat Tool ◽  
Element Method

A majority of the finished products made by metal forming are geometrically complex and the metal flow involved is of a three-dimensional nature. Thus, any analysis technique will become more useful in industrial applications if it is capable of solving three-dimensional metal-flow problems. Nagpal and Altan introduced dual-stream functions for describing metal flow in three dimensions. This work showed that the proper selection of a flow function makes the incompressibility requirement automatically satisfied and provides general kinematically admissible velocity fields. Yang and Lee utilized the conformal transformation of a unit circle onto a cross-section in the analysis of curved die extrusion. They derived the stream-line equation from which a kinematically admissible velocity field was determined. The upper-bound method was then applied to determine the extrusion pressure for a rigid-perfectly plastic material. An important aspect of three-dimensional plastic deformation is the analysis of spread in metal-forming operations, such as spread in rolling or in flat tool forging, and spread in compression of noncircular disks. Solutions to such problems have been obtained by the use of Hill’s general method and the upper-bound method. The extension of the finite-element method to solve three-dimensional problems is natural and not new, particularly in the area of elasticity. However, the simulation of three-dimensional forming operations by the finite-element method is relatively recent. Park and Kobayashi described the formulation for the three-dimensional rigid-plastic finite-element method and the implementation of the boundary conditions. They applied this technique to the analysis of block compression between two parallel flat platens. For certain forming problems, such as those involving lateral spread, the use of a simplified three-dimensional element is efficient and some examples can be found for analysis of spread in rolling and flat tool forging. The matrices for evaluation of elemental stiffness equations are defined for a three-dimensional brick element in Chap. 6 and some of them are recapitulated in this section. A three-dimensional brick element used for the analysis is an eight-node hexahedral isoparametric element.

Evaluation of Thermal and Mechanical Behaviors of Pipe Flange Connections for Low Temperature Fluids by Numerical Analysis and Experiments

2016 ◽  
Author(s):  
Toshimichi Fukuoka
Keyword(s):  
Low Temperature ◽  
Numerical Method ◽  
Elevated Temperatures ◽  
Three Dimensional ◽  
Mechanical Behaviors ◽  
Flow Conditions ◽  
Initial Value ◽  
Leakage Mechanism ◽  
Rate Of Increase ◽  
Good Agreement

Sealing of contained fluids is the primary criteria required for pipe flange connections. Recently, there is a rapid rate of increase in the use of low temperature fluids, and leakage related accidents are sometimes reported. The leakage mechanism seems to be different from the case in pipe flange connections at elevated temperatures. In this paper, it is examined experimentally how the leakage of low temperature fluids occurs, in which a pipe flange connection is cooled by liquid nitrogen. The variations of bolt temperature and bolt force are continuously measured. Experimental results show that the bolt force is reduced to as low as about 65% of the initial value. Next, a numerical method based on three-dimensional FEM is proposed to simulate the cooling process. Numerical results are in good agreement with those obtained by experiments. Applying the numerical method to the pipe flange connections for LNG, it is found that the bolt force reduces to about 70% of the initial value. The numerical method proposed in this paper is expectantly applied to the cases of different low temperature fluids under various flow conditions.

Finite Element Simulation of the Self-Piercing Riveting Process

2008 ◽  
Author(s):  
S. G. Qu ◽  
W. J. Deng
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Process Simulation ◽  
Metal Flow ◽  
The Self ◽  
Finite Element Code ◽  
The Finite Element Method ◽  
Element Simulation ◽  
Riveting Process ◽  
Good Agreement

This work is focused on the development of a numerical model with the help of the finite element method to predict the magnitude and distribution of deformation associated with the self-piercing riveting process. A 2D axisymmetric model of the self-piercing riveting process is presented using the commercial implicit finite element code MSC.Superform. The flow stress of the work-material is taken as a function of strain, strain-rate and temperature. The shape of the rivet joint and the stress, strain and damage in both of the rivet and workpiece sheets are determined. The information obtained from the process simulation, such as force, metal flow and details of die fill are discussed. The calculated punching forces and the shape of the rivet joint are compared with experimental data and found to be in good agreement. Defects in the riveting are analyzed and are categorized into penetration, necking and lap formation. The effects of workpiece temperature on punching force were also discussed.

scholarly journals Three-dimensional Finite Element Modelling of the Cylindrical Specimen Upsetting

2018 ◽  
Vol 220 ◽  
pp. 04008 ◽  
Author(s):  
Mikhail V. Murashov ◽  
Andrey V. Vlasov
Keyword(s):  
Finite Element ◽  
Metal Forming ◽  
Three Dimensional ◽  
The Finite Element Method ◽  
Numerical Errors ◽  
Finite Element Software ◽  
Dimensional Finite Element ◽  
Calculation Results ◽  
Three Dimensional Finite Element ◽  
Good Agreement

Friction has a substantial influence on the metal forming at upsetting of cylindrical aluminum specimens. The finite element method is often used to investigate this problem. This paper aims to reveal possible numerical errors and obstacles related to the 3D finite element solution of the problem. The calculation results for the proposed numerical 3D-model are compared with the experimental data. The influence of friction is demonstrated and a good agreement on the tool displacement is obtained. The features of the numerical solution of the problem in the ANSYS finite element software are shown.

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