Development of Free Surface Roughness in Expanding/Contracting Cylinders

2008 ◽  
Author(s):  
Sergei Alexandrov ◽  
Ken-Ichi Manabe ◽  
Tsuyoshi Furushima
Keyword(s):  
Surface Roughness ◽  
Finite Element ◽  
Free Surface ◽  
Classical Problem ◽  
Modern Technology ◽  
Simple Problem ◽  
Material Models ◽  
Theoretical Predictions ◽  
Element Technique ◽  
Metallic Parts

Microforming is a modern technology for fabricating very small metallic parts, such as micro-tubes, required in many sectors of industry. Free surface roughness of such components is a very important parameter since the roughness can be considered as the variation of component dimensions in this case. It is therefore of importance to understand an effect of process parameters and parameters of material models used to describe the evolution of roughness on the final result of theoretical predictions. To this end, it is possible to study the solution behavior of a simple problem even if it is not feasible for experimental verification. In the present paper, the solution to a classical problem of plasticity, expansion/contraction of a hollow cylinder, is combined with a finite element technique to predict the evolution of roughness at the free surface.

scholarly journals Finite Element Modeling and Validation of Metal Deposition in Wire Arc Additive Manufacturing

2021 ◽  
pp. 61-66
Author(s):  
Akram Chergui ◽  
Nicolas Beraud ◽  
Frédéric Vignat ◽  
François Villeneuve
Keyword(s):  
Finite Element ◽  
Additive Manufacturing ◽  
Large Scale ◽  
Low Cost ◽  
Source Model ◽  
Metal Deposition ◽  
High Deposition Rate ◽  
Element Technique ◽  
Metallic Parts ◽  
Wire Arc Additive Manufacturing

AbstractWire arc additive manufacturing allows the production of metallic parts by depositing beads of weld metal using arc-welding technologies. This low-cost additive manufacturing technology has the ability to manufacture large-scale parts at a high deposition rate. However, the quality of the obtained parts is greatly affected by the various thermal phenomena present during the manufacturing process. Numerical simulation remains an effective tool for studying such phenomena. In this work, a new finite element technique is proposed in order to model metal deposition in WAAM process. This technique allows to gradually construct the mesh representing the deposited regions along the deposition path. The heat source model proposed by Goldak is adapted and combined with the proposed metal deposition technique taking into account the energy distribution between filler material and the molten pool. The effectiveness of the proposed method is validated by series of experiments, of which an example is detailed in this paper.

Inhomogeneous 3D Finite Element Model for Prediction of Free Surface Roughening

2011 ◽  
Vol 418-420 ◽  
pp. 1040-1043 ◽  
Author(s):  
Tsuyoshi Furushima ◽  
Tetsuro Masuda ◽  
Kenichi Manabe ◽  
Sergei Alexandrov
Keyword(s):  
Surface Roughness ◽  
Finite Element ◽  
Free Surface ◽  
Experimental Result ◽  
Surface Roughening ◽  
Sensitivity Index ◽  
Fe Model ◽  
K Value ◽  
3D Finite Element ◽  
Material Inhomogeneity

In this study, we evaluated the characteristics of 3D finite element (FE) model considering material inhomogeneity for prediction of free surface roughening. Free surface roughening behavior can be observed by this model. The variation in material inhomogeneity parameter value has a strong correlation with the rate of increase in the surface roughness. macroscopic strength coefficient K value does absolutely not affect the rate of increasing surface roughness. Strain hardening sensitivity index n value slightly affects the free surface roughening behavior. The true stress – true strain curve of the inhomogeneous FE model is in good agreement with those of the homogeneous FE model and the experimental result. As a result, the characteristics evaluation of suggested model considering material inhomogeneity is conducted.

Contact Analysis of Tire Tread Rubber on Flat Surface with Microscopic Roughness3

2006 ◽  
Vol 34 (4) ◽  
pp. 237-255 ◽  
Author(s):  
M. Kuwajima ◽  
M. Koishi ◽  
J. Sugimura
Keyword(s):  
Surface Roughness ◽  
Finite Element ◽  
Sliding Friction ◽  
Tangential Force ◽  
Partial Slip ◽  
Real Contact Area ◽  
Element Analysis ◽  
Real Contact ◽  
Local Slip ◽  
Tread Rubber

Abstract This paper describes experimental and analytical studies of the dependence of tire friction on the surface roughness of pavement. Abrasive papers were adopted as representative of the microscopic surface roughness of pavement surfaces. The rolling∕sliding friction of tire tread rubber against these abrasive papers were measured at low slip velocities. Experimental results indicated that rolling∕sliding frictional characteristics depended on the surface roughness. In order to examine the interfacial phenomena between rubber and the abrasive papers, real contact length, partial slip, and apparent friction coefficient under vertical load and tangential force were analyzed with two-dimensional explicit finite element analysis in which slip-velocity-dependent frictional coefficients were considered. Finite element method results indicated that the sum of real contact area and local partial slip were larger for finer surfaces under the same normal and tangential forces. In addition, the velocity-dependent friction enhanced local slip, where the dependence of local slip on surface roughness was pronounced. It proved that rolling∕sliding friction at low slip ratio was affected by local frictional behavior at microslip regions at asperity contacts.

scholarly journals Downscaled Finite Element Modeling of Metal Targets for Surface Roughness Level under Pulsed Laser Irradiation

2021 ◽  
Vol 11 (3) ◽  
pp. 1253
Author(s):  
Evaggelos Kaselouris ◽  
Kyriaki Kosma ◽  
Yannis Orphanos ◽  
Alexandros Skoulakis ◽  
Ioannis Fitilis ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Finite Element ◽  
Surface Acoustic Waves ◽  
Pulsed Laser ◽  
Multiscale Simulation ◽  
Experimental Methodology ◽  
Computational Domain ◽  
Area Of Interest ◽  
Depth Analysis ◽  
Laser Solid Interactions

A three-dimensional, thermal-structural finite element model, originally developed for the study of laser–solid interactions and the generation and propagation of surface acoustic waves in the macroscopic level, was downscaled for the investigation of the surface roughness influence on pulsed laser–solid interactions. The dimensions of the computational domain were reduced to include the laser-heated area of interest. The initially flat surface was progressively downscaled to model the spatial roughness profile characteristics with increasing geometrical accuracy. Since we focused on the plastic and melting regimes, where structural changes occur in the submicrometer scale, the proposed downscaling approach allowed for their accurate positioning. Additionally, the multiscale simulation results were discussed in relation to experimental findings based on white light interferometry. The combination of this multiscale modeling approach with the experimental methodology presented in this study provides a multilevel scientific tool for an in-depth analysis of the influence of heat parameters on the surface roughness of solid materials and can be further extended to various laser–solid interaction applications.

scholarly journals The Force Cone Method Applied to Explain Hidden Whirls in Tribology

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3894
Author(s):  
Claus Mattheck ◽  
Christian Greiner ◽  
Klaus Bethge ◽  
Iwiza Tesari ◽  
Karlheinz Weber
Keyword(s):  
Finite Element ◽  
Free Surface ◽  
Simple Model ◽  
Alternative Explanation ◽  
Model Experiments ◽  
Complex Processes ◽  
Buried Interfaces ◽  
Internal Structures ◽  
Ideal Tool ◽  
Acting Force

In tribologically loaded materials, folding instabilities and vortices lead to the formation of complex internal structures. This is true for geological as well as nanoscopic contacts. Classically, these structures have been described by Kelvin–Helmholtz instabilities or shear localization. We here introduce an alternative explanation based on an intuitive approach referred to as the force cone method. It is considered how whirls are situated near forces acting on a free surface of an elastic or elastoplastic solid. The force cone results are supplemented by finite element simulations. Depending on the direction of the acting force, one or two whirls are predicted by the simplified force cone method. In 3D, there is always a ring shaped whirl present. These modelling findings were tested in simple model experiments. The results qualitatively match the predictions and whirl formation was found. The force cone method and the experiments may seem trivial, but they are an ideal tool to intuitively understand the presence of whirls within a solid under a tribological load. The position of these whirls was found at the predicted places and the force cone method allows a direct approach to understand the complex processes in the otherwise buried interfaces of tribologically loaded materials.

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