Speeding-up numerical simulation of 3D forging through recurrent boundary contact conditions

2019 ◽  
Author(s):  
S. Marie ◽  
C. Beraudo ◽  
L. Fourment
Keyword(s):  
Numerical Simulation ◽  
Contact Conditions ◽  
Boundary Contact

Thermo-mechanical modelling of the Friction Stir Spot Welding process: Effect of the friction models on the heat generation mechanisms

2022 ◽  
pp. 146442072110709
Author(s):  
Nasra Hannachi ◽  
Ali Khalfallah ◽  
Carlos Leitão ◽  
Dulce Rodrigues
Keyword(s):  
Numerical Simulation ◽  
Heat Generation ◽  
Spot Welding ◽  
Welding Process ◽  
Friction Stir Spot Welding ◽  
Frictional Heat ◽  
Contact Conditions ◽  
Friction Stir ◽  
Friction Models ◽  
Generation Mechanisms

Friction Stir Spot Welding involves complex physical phenomena, which are very difficult to probe experimentally. In this regard, the numerical simulation may play a key role to gain insight into this complex thermo-mechanical process. It is often used to mimic specific experimental conditions to forecast outputs that may be substantial to analyse and elucidate the mechanisms behind the Friction Stir Spot Welding process. This welding technique uses frictional heat generated by a rotating tool to join materials. The heat generation mechanisms are governed by a combination of sliding and sticking contact conditions. In the numerical simulation, these contact conditions are thoroughly dependent on the used friction model. Hence, a successful prediction of the process relies on the appropriate selection of the contact model and parameters. This work aims to identify the pros and cons of different friction models in modelling combined sliding-sticking conditions. A three-dimensional coupled thermo-mechanical FE model, based on a Coupled Eulerian-Lagrangian formulation, was developed. Different friction models are adopted to simulate the Friction Stir Spot Welding of the AA6082-T6 aluminium alloy. For these friction models, the temperature evolution, the heat generation, and the plastic deformation were analysed and compared with experimental results. It was realized that numerical analysis of Friction Stir Spot Welding can be effective and reliable as long as the interfacial friction characteristics are properly modelled. This approach may be used to guide the contact modelling strategy for the simulation of the Friction Stir Spot Welding process and its derivatives.

scholarly journals Numerical simulation and analytical study of glulam timber beams

2014 ◽  
Vol 3 (2) ◽  
pp. 129 ◽  
Author(s):  
Themistoklis Tsalkatidis
Keyword(s):  
Numerical Simulation ◽  
Three Dimensional ◽  
Contact Conditions ◽  
Glulam Beam ◽  
Dimensional Finite Element ◽  
Thick Steel ◽  
Support Conditions ◽  
The One ◽  
Three Dimensional Finite Element ◽  
Timber Beams

Glulam beams or glued-laminated beams consist of sawn lumber laminations (timber) bonded with an adhesive material. This paper, through the mathematical description of the contact conditions that apply at the interfaces of glulam beams and the development of two three-dimensional finite element models by the use of the ANSYS software package, studies the flexural properties of unreinforced (UGB) and reinforced (RGB) glulam beams. The first computational model presents an unreinforced glulam beam that has been produced by three wood laminations of dimensions 6 by 3.6 by 176 cm. The latter one describes a reinforced glulam beam, which has been produced by gluing a 0.15 cm thick steel plate at the bottom edge of the previously described beam. The computational analysis indicates that the two glulam beams have significantly different bearing capacities under the same load and support conditions. The failure mode of the UGB is brittle whereas the one of the RGB is ductile. The numerical results of both models are in close agreement with experimental ones from the international literature. Keywords: Glulam Timber Beams, Numerical Simulation, Contact.

scholarly journals Some Problems of Thermoelastic Equilibrium of a Rectangular Parallelepiped in Terms of Asymmetric Elasticity

2001 ◽  
Vol 8 (4) ◽  
pp. 767-784
Author(s):  
N. Khomasuridze
Keyword(s):  
Thermal Field ◽  
Separation Of Variables ◽  
Contact Problems ◽  
Rectangular Parallelepiped ◽  
Effective Solution ◽  
Contact Conditions ◽  
Thermoelastic Equilibrium ◽  
Boundary Contact ◽  
Asymmetric Elasticity ◽  
Surface Disturbances

Abstract An effective solution of a number of boundary value and boundary contact problems of thermoelastic equilibrium is constructed for a homogeneous isotropic rectangular parallelepiped in terms of asymmetric and pseudo-asymmetric elasticity (Cosserat's continuum and pseudo- continuum). Two opposite faces of a parallelepiped are affected by arbitrary surface disturbances and a stationary thermal field, while for the four remaining faces symmetry or anti-symmetry conditions (for a multilayer rectangular parallelepiped nonhomogeneous contact conditions are also defined) are given. The solutions are constructed in trigonometric series using the method of separation of variables.

Numerical Investigation on the Structural Behavior of a Composite Impact Absorber

2009 ◽  
Vol 417-418 ◽  
pp. 685-688 ◽  
Author(s):  
Giuseppe Lamanna ◽  
Francesco Caputo ◽  
Alessandro Soprano
Keyword(s):  
Numerical Investigation ◽  
Laminated Composite ◽  
Failure Criteria ◽  
Point Of View ◽  
Physical Parameters ◽  
Contact Conditions ◽  
Explicit Finite Element ◽  
Energy Absorbing ◽  
Boundary Contact ◽  
Composite Face

The energy absorption capability of an exposed crashworthy element or system is largely affected by material properties and structural design: prismatic sandwich structures, made of foam or honeycomb core between two metallic or laminated composite face plates, are good candidates. This work deals with a numerical investigation on the energy absorbing capability of such a structural component. There are several difficulties associated with the numerical simulation of a composite impact-absorber, such as high geometrical non-linearities, boundary contact conditions, failure criteria, material behaviour; that is because the main objectives of any numerical investigation are the calibration of the model with experimental results and the evaluation of the sensitivity of the variables with respect to the geometrical and physical parameters which influence the study at hand. The latter is a very relevant aspect for designers if the application of the model to real cases has to be a robust one from both a physical and a numerical point of view. In this paper a preliminary calibration of a numerical model for a composite impact absorber is presented, on the basis of experimental data found in literature; then a sensitivity analysis of the same model to the variation of the main geometrical and material parameters, developed by using the explicit finite element algorithms implemented in the Ls-Dyna code, is illustrated.

Towards the Mastering of the Free Surface Position in Roll Coating

2007 ◽  
Vol 344 ◽  
pp. 955-962
Author(s):  
E. Szczurek ◽  
M. Dubar ◽  
R. Deltombe ◽  
A. Dubois ◽  
L. Dubar
Keyword(s):  
Numerical Simulation ◽  
Free Surface ◽  
Compression Tests ◽  
Contact Conditions ◽  
Roll Coating ◽  
Real Contact ◽  
Cyclic Compression ◽  
Viscoelastic Parameters ◽  
Element Simulation ◽  
Behaviour Law

This paper deals with an industrial three rolls coater. The behaviour law of the elastomer roll cover in different environments is first established in order to be taken into account in the numerical simulation of the process. Cyclic compression tests are performed and compared to the corresponding numerical simulation to precisely determine the viscoelastic parameters. With the identified parameters, a finite element simulation of the process is then performed to evaluate the meniscus stability in real contact conditions. The influence of the determined elastomer behaviour laws on the free surface position is discussed.

scholarly journals Experimental and numerical impact models of protection fences

2019 ◽  
Vol 11 (1) ◽  
pp. 90-108
Author(s):  
Trung Tran Le Hoang ◽  
Hiroshi Masuya ◽  
Yoichi Nishita ◽  
Taichi Ishii
Keyword(s):  
Numerical Simulation ◽  
Finite Element ◽  
Impact Energy ◽  
Mountainous Areas ◽  
Contact Conditions ◽  
Wire Ropes ◽  
Energy Absorbers ◽  
Full Scale Tests ◽  
The Impact ◽  
Impact Models

The essential requirements for the protection of structures in mountainous areas against rockfalls have led to the development of various types of protection fences. Herein, we conducted impact tests on the protection fence by changing the heights of its posts and collision positions to evaluate adequately and precisely the absorbable capacity of the impact energy. In all experimental cases, the protection fence, which had a span of 5 m and posts with the heights of 2 and 3 m, exhibited an outstanding capacity for dissipating the impact energy of 50 kJ in accordance with a rational arrangement of energy absorbers, which caused the effective slipping of wire ropes. In addition, the simplest possible assumptions adopted in numerical simulations are presented clearly and in detail in terms of the choice of finite element shapes, constitutive laws, and contact conditions, so that the model of the numerical simulation can reproduce successfully the dynamic behavior of the protection fence. Furthermore, this numerical model can aid or replace the full-scale tests to attain an improved capacity for absorbing the energy of rockfall.

Friction and Wear in Metal Forming: 25 Years at LAMIH UMR CNRS 8201

2018 ◽  
Vol 767 ◽  
pp. 42-58 ◽  
Author(s):  
Laurent Dubar ◽  
André Dubois ◽  
Mirentxu Dubar
Keyword(s):  
Numerical Simulation ◽  
Finite Element ◽  
Friction Coefficient ◽  
Metal Forming ◽  
Friction And Wear ◽  
Forming Process ◽  
Contact Conditions ◽  
Manufacturing Plants ◽  
Bulk Forming ◽  
Research Activities

Since the beginning of the 90’s, research activities focused on friction and wear in metal forming have been developed at the LAMIH UMR CNRS 8201 in Valenciennes. Specific methodologies have been designed to optimize a given forming process (bulk forming process or sheet forming process). These methodologies involve prototype benches which have been built to reproduce contact conditions encountered in manufacturing plants by taking specimens and contactors from the real industrial workpieces and tools. The evaluation of the friction coefficient added to the fine analysis of the surfaces have helped us to better understand friction and wear during processes. These facilities have been settled by numerical simulation at meso and macro scales by means of finite element methods. So, this paper is the sum up of the output of these methodologies with a specific focus on wear and lubrication, at room and hot temperatures.

Experimental-numerical analysis of contact conditions influence on the ironing strip drawing process

2017 ◽  
Vol 69 (4) ◽  
pp. 464-470
Author(s):  
Milan Djordjević ◽  
Vesna Mandić ◽  
Srbislav Aleksandrović ◽  
Vukić Lazić ◽  
Dušan Arsić ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Numerical Analysis ◽  
Physical Modeling ◽  
Thin Sheet ◽  
Process Conditions ◽  
Drawing Process ◽  
Contact Conditions ◽  
Important Indicator ◽  
Content Type ◽  
Strip Drawing

Purpose The purpose of this paper is comparison of experimental values of the drawing forces to numerical values in different contact conditions, taking into account the appearance of galling which occurs due to of difficult drawing process conditions. Design/methodology/approach The following two research approaches are used in this paper – the physical modeling, realized by the laboratory experiment, and the numerical simulation of the ironing drawing process. By analyzing the obtained results, the technique of physical modeling, with help of the laboratory equipment and numerical simulation by application of the finite element method, can be successfully used in studying the thin sheet ironing – strip drawing process. Findings It is significant to compare values of the deformation forces obtained by physical experiment to values obtained by the numerical simulation. In that way, it is possible to compare applied contact conditions (four lubricants in that case) and estimate matching of experimentally and numerically obtained results of the deformation forces. Presented results point out very good technological characteristics of ecologically friendly lubricant (single-bath) and grease based on MoS2. Significant decrease of the deformation force was achieved by its application, as well as maintaining of the lubricant’s layer during the forming process and almost complete elimination of galling on the contact. Practical implications Numerical analysis of stresses in the working piece wall, during the thin sheet strip drawing, requires precise values of the friction coefficient. It is an important indicator because one can define the contact conditions as the input data for the numerical simulation, based on its values for each type of lubricants and each value of the compressive lateral force. Originality/value The environmentally friendly lubricant tested exhibits a more favorable distribution of the drawing force during the process, mainly in experimental case. Grease based on MoS2 has good lubricating properties but that lubricant is conventional and environmentally unacceptable. Ecologically friendly lubricant can be successfully used in real ironing strip drawing process especially for high values of holding force achieving an increased tool life.

scholarly journals Taking into account the fluid saturation of bottom sediments in marine seismic survey problem

2019 ◽  
Vol 488 (3) ◽  
pp. 248-252 ◽  
Author(s):  
V. I. Golubev ◽  
A. V. Shevchenko ◽  
I. B. Petrov
Keyword(s):  
Numerical Simulation ◽  
Seismic Response ◽  
Bottom Sediments ◽  
Distinctive Feature ◽  
Seismic Survey ◽  
Characteristic Method ◽  
Contact Conditions ◽  
Fluid Saturation ◽  
Acoustic Equations ◽  
Marine Seismic

The problem of the numerical simulation of the seismic response from the marine bottom is considered. Acoustic equations are used for the description of the water dynamic behavior. Bottom sediments are described with the porous fluid-filled medium. The Dorovsky model is used. The algorithm for solving all hyperbolic equation systems with the grid-characteristic method was proposed. The distinctive feature of this approach is the ability to set explicitly necessary contact conditions between media with different rheology.

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