scholarly journals A multiscale MD–FE model of diffusion in composite media with internal surface interaction based on numerical homogenization procedure

2014 ◽  
Vol 269 ◽  
pp. 123-138 ◽  
Author(s):  
M. Kojic ◽  
M. Milosevic ◽  
N. Kojic ◽  
K. Kim ◽  
M. Ferrari ◽  
...  
Keyword(s):  
Internal Surface ◽  
Surface Interaction ◽  
Fe Model ◽  
Numerical Homogenization ◽  
Composite Media ◽  
Homogenization Procedure

Effective Properties of Superconducting and Superfluid Composites

1998 ◽  
Vol 12 (29n31) ◽  
pp. 3063-3073 ◽  
Author(s):  
Leonid Berlyand
Keyword(s):  
Mathematical Model ◽  
Linear Problem ◽  
Effective Properties ◽  
Point Of View ◽  
Periodicity Cell ◽  
Unit Size ◽  
Composite Media ◽  
Homogenization Procedure

We consider a mathematical model which describes an ideal superfluid with a large number of thin insulating rods and an ideal superconductor reinforced by such rods. We suggest a homogenization procedure for calculating effective properties of both composite media. From the numerical point of view the procedure amounts to solving a linear problem in a periodicity cell of unit size.

Flexure based gripper to grasp hollow objects by internal surface interaction

2021 ◽  
pp. 095440622110498
Author(s):  
Rajesh Kumar ◽  
Harsh Yadav ◽  
Varan Gupta ◽  
Jitendra P Khatait
Keyword(s):  
Internal Surface ◽  
Surface Interaction ◽  
Design Development ◽  
Friction Forces ◽  
Normal Forces ◽  
Inner Surface

The paper focuses on the design, development, and evaluation of a gripper intended to hold hollow objects by interacting with the inner surface. The gripper moves towards the inside of the hollow object and grips it using the friction forces applied on the surface of the object. The design also ensures the application of variable normal forces on the surface of the object to be grasped. The mathematical architecture is verified using prototypes and experiments.

Evolution Regularity of Temperature Filed in Hot Power Backward Spinning for 7075 Cast Aluminium Alloy Tube

2013 ◽  
Vol 774-776 ◽  
pp. 1170-1173 ◽  
Author(s):  
R.Y. Zhang ◽  
S.J. Tu ◽  
G.Y. Zhao ◽  
J. Wang ◽  
Z.H. Guo
Keyword(s):  
Aluminium Alloy ◽  
Internal Surface ◽  
Fe Model ◽  
Outer Face ◽  
Key Factors ◽  
Ring Spinning ◽  
Alloy Tube ◽  
Temperature Filed ◽  
Spinning Process ◽  
Lock Ring

The spinning temperature is one of key factors affected the uneven deformation during the hot power backward spinning for brittle material tubes, such as cast 7075 aluminium alloy tube. To analyze the evolution regularity of temperature filed in the spinning process, a 3D thermo-mechanical FE model of the process is developed under ABAQUS/Explicit environment. Then, the evolution of temperature filed during the process is analyzed based on the FE model. The results show that: The contact areas temperatures between lock ring, spinning rollers and tube decrease sharply during the initial spinning stage. The high temperature region is transferred from unformed zone of the tube to the contact area between spinning roller and tube. In the spinning zone, the temperature of internal surface of the tube is apparently higher than that of outer face.

scholarly journals Numerical design of load response in magneto-rheological actuators for sheet metal stamping

2021 ◽  
Author(s):  
Michele Brun ◽  
Andrea Ghiotti ◽  
Enrico Simonetto ◽  
Stefania Bruschi
Keyword(s):  
Fluid Flows ◽  
Internal Surface ◽  
Sheet Forming ◽  
Fe Model ◽  
Hydraulic Actuator ◽  
Mr Fluid ◽  
Load Response ◽  
Geometrical Features ◽  
Metal Stamping ◽  
Magneto Rheological

Auxiliary systems for sheet forming processes are widely used to improve products accuracy and increase tools life. As example, in blanking hydraulic dampers are widely used to reduce shocks and vibrations; nitrogen springs are often integrated in deep drawing tools to correct the ram tilt or to locally increase the blank-holder force, obtaining geometrical features on the stamped blank with one press pass. In this paper, a Magneto-Rheological (MR) semi-active actuator is developed for sheet forming operations and the interaction between MR fluid and electromagnetic field is investigated by Finite Element (FE) analysis. To overcome the limitations of gas springs and hydraulic actuator, the static electromagnetic circuits is reconfigured with respect of conventional MR actuators known in the state-of-the-art. The novel MR actuator has an inner bore where the electric windings are placed, while the narrow gap, in which the active MR fluid flows, is obtained between the inner bore and the cylinder internal surface. The resulting magnetic fields H and induction fields B, as well as the selection of components materials, are studied through the magneto-static FE model. The results from FE simulations show a longer activation length along the gap resulting in higher controllable forces values, without increasing the overall dimensions of the proposed prototype.

scholarly journals DETERMINATION OF HYGROEXPANSION COEFFICIENTS OF WOOD USING ANALYTICAL AND NUMERICAL HOMOGENIZATION

2018 ◽  
Vol 15 ◽  
pp. 51-56
Author(s):  
Lucie Kucíková ◽  
Michal Šejnoha ◽  
Jan Vorel
Keyword(s):  
Thermal Expansion ◽  
Moisture Content ◽  
Wood Density ◽  
Coefficient Of Thermal Expansion ◽  
Numerical Homogenization ◽  
Homogenization Procedure ◽  
Volume Fractions ◽  
Dry Wood ◽  
Hygroscopic Material

This paper is concerned with the determination of hygroexpansion coefficients of wood. Wood is a naturally hygroscopic material, attracting moisture from its surroundings. Its dimensions change depending on the actual moisture content. This dependence is characterized by the coefficient of hygroexpansion. For complex microstructures, this coefficient can be determined, similarly to the coefficient of thermal expansion, either from analytical or numerical homogenization. The homogenization procedure, used in this paper, comprises several steps corresponding to the wood structural composition. Accuracy of this approach is governed by correctness of the chosen input parameters. One of the most important parameters are the volume fractions of the earlywood and latewood. Ascertained dependence of the earlywood and latewood volume fractions on dry wood density is also presented.

scholarly journals Solid Truss to Shell Numerical Homogenization of Prefabricated Composite Slabs

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4120
Author(s):  
Natalia Staszak ◽  
Tomasz Garbowski ◽  
Anna Szymczak-Graczyk
Keyword(s):  
Composite Structures ◽  
Homogenization Method ◽  
Fe Model ◽  
Structural Elements ◽  
Numerical Homogenization ◽  
Single Plate ◽  
Energy Equivalence ◽  
Numerical Tools ◽  
Simplified Procedures ◽  
Excellent Tool

The need for quick and easy deflection calculations of various prefabricated slabs causes simplified procedures and numerical tools to be used more often. Modelling of full 3D finite element (FE) geometry of such plates is not only uneconomical but often requires the use of complex software and advanced numerical knowledge. Therefore, numerical homogenization is an excellent tool, which can be easily employed to simplify a model, especially when accurate modelling is not necessary. Homogenization allows for simplifying a computational model and replacing a complicated composite structure with a homogeneous plate. Here, a numerical homogenization method based on strain energy equivalence is derived. Based on the method proposed, the structure of the prefabricated concrete slabs reinforced with steel spatial trusses is homogenized to a single plate element with an effective stiffness. There is a complete equivalence between the full 3D FE model built with solid elements combined with truss structural elements and the simplified homogenized plate FE model. The method allows for the correct homogenization of any complex composite structures made of both solid and structural elements, without the need to perform advanced numerical analyses. The only requirement is a correctly formulated stiffness matrix of a representative volume element (RVE) and appropriate formulation of the transformation between kinematic constrains on the RVE boundary and generalized strains.

scholarly journals 3D finite element model based on CT images of tooth

2020 ◽  
Vol 19 ◽  
pp. e208910
Author(s):  
Germana De Villa Camargos ◽  
Priscilla Cardoso Lazari-Carvalho ◽  
Marco Aurélio de Carvalho ◽  
Mariane Boaventura Castro ◽  
Naysa Wink Neris ◽  
...  
Keyword(s):  
Finite Element ◽  
Computer Aided Design ◽  
Internal Surface ◽  
Fe Model ◽  
Central Incisor ◽  
Incisor Tooth ◽  
Element Analysis ◽  
3D Finite Element ◽  
Maxillary Central Incisor ◽  
Core Materials

Aim: This study aimed the description of a protocol to acquire a 3D finite element (FE) model of a human maxillary central incisor tooth restored with ceramic crowns with enhanced geometric detail through an easy-to-use and low-cost concept and validate it through finite element analysis (FEA). Methods: A human maxillary central incisor was digitalized using a Cone Beam Computer Tomography (CBCT) scanner. The resulted tooth CBCT DICOM files were imported into a free medical imaging software (Invesalius) for 3D surface/geometric reconstruction in stereolithographic file format (STL). The STL file was exported to a computer-aided-design (CAD) software (SolidWorks), converted into a 3D solid model and edited to simulate different materials for full crown restorations. The obtained model was exported into a FEA software to evaluate the influence of different core materials (zirconia - Zr, lithium disilicate - Ds or palladium/silver - Ps) on the mechanical behavior of the restorations under a 100 N applied to the palatal surface at 135 degrees to the long axis of the tooth, followed by a load of 25.5 N perpendicular to the incisal edge of the crown. The quantitative and qualitative analysis of maximum principal stress (ceramic veneer) and maximum principal strain (core) were obtained. Results: The Zr model presented lower stress and strain concentration in the ceramic veneer and core than Ds and Ps models. For all models, the stresses were concentrated in the external surface of the veneering ceramic and strains in the internal surface of core, both near to the loading area. Conclusion: The described procedure is a quick, inexpensive and feasible protocol to obtain a highly detailed 3D FE model, and thus could be considered for future 3D FE analysis. The results of numerical simulation confirm that stiffer core materials result in a reduced stress concentration in ceramic veneer.

Wang Tilings in Numerical Homogenization

2016 ◽  
Vol 821 ◽  
pp. 489-494
Author(s):  
Martin Doškář ◽  
Jan Novák
Keyword(s):  
Domain Decomposition ◽  
Decomposition Method ◽  
Domain Decomposition Method ◽  
Computational Cost ◽  
Unit Cell ◽  
Numerical Homogenization ◽  
Homogenization Procedure ◽  
Conventional Unit

Stochastic Wang tiling has been shown to bring unexpected insights to microstructure representation efforts as it generalizes the conventional unit-cell approach. It allows to reconstruct stochastic realizations of the compressed medium without prior periodic assumptions on microstructural patterns. Moreover, once the microstructure is compressed, its realizations of various sizes can be generated at almost negligible cost. In this paper, we follow the standard numerical homogenization procedure and make use of the realizations as domains over which local quantities are computed and averaged subsequently. In order to alleviate computational cost, a domain decomposition method is adopted such that it benefits from the fact that the computational domains are composed of limited number of repetitive patterns -- tiles.

scholarly journals Solid-Truss to Shell Numerical Homogenization of Prefabricated Composite Slabs

2021 ◽  
Author(s):  
Natalia Staszak ◽  
Tomasz Garbowski ◽  
Anna Szymczak-Graczyk
Keyword(s):  
Composite Structures ◽  
Homogenization Method ◽  
Fe Model ◽  
Structural Elements ◽  
Numerical Homogenization ◽  
Single Plate ◽  
Energy Equivalence ◽  
Numerical Tools ◽  
Simplified Procedures ◽  
Excellent Tool

The need for quick and easy deflection calculations of various prefabricated slabs causes that simplified procedures and numerical tools are used more and more often. Modelling of full 3D finite element (FE) geometry of such plates is not only uneconomical but often requires the use of complex software and advanced numerical knowledge. Therefore, numerical homogenization is an excellent tool, which can be easily employed to simplify a model, especially when accurate modelling is not necessary. Homogenization allows for simplifying a computational model and replacing a complicated composite structure with a homogeneous plate. Here, a numerical homogenization method based on strain energy equivalence is derived. Using the method proposed, the structure of the prefabricated concrete slabs reinforced with steel spatial trusses is homogenized to a single plate element with an effective stiffness. There is a complete equivalence between the full 3D FE model built with solid elements combined with truss structural elements and the simplified homogenized plate FE model. The method allows for the correct homogenization of any complex composite structures made of both solid and structural elements, without the need to perform advanced numerical analyses. The only requirement is a correctly formulated stiffness matrix of a representative volume element (RVE) and appropriate formulation of the transformation between kinematic constrains on RVE boundary and generalized strains.

A Hybrid LP/FE Model for the Dynamic Analysis of External Gear Pumps

2007 ◽  
Author(s):  
Emiliano Mucchi ◽  
Valerio Venturi ◽  
Giorgio Dalpiaz
Keyword(s):  
Finite Element ◽  
Internal Surface ◽  
Element Model ◽  
Design Parameters ◽  
Fe Model ◽  
Gear Pump ◽  
Time Varying ◽  
Pump Operation ◽  
Lumped Parameter ◽  
Lp Model

In this work a hybrid lumped-parameter finite-element model of an external gear pump for automotive applications is presented and experimentally assessed; the finite element (FE) model regards the external parts of the pump (case and end plates) while the lumped-parameter (LP) model regards the interior parts (bushes and gears). The LP model is a non linear kineto-elastodynamic model and includes the most important phenomena involved in the pump operation as time-varying oil pressure distribution on gears, time-varying meshing stiffness and hydrodynamic journal bearing reactions. A forced vibration analysis has been carried out by means of the FE model for the evaluation of the acceleration levels on the external surfaces of the pump; for this analysis, the damping has been estimated using data coming from an experimental modal analysis (EMA) whereas the excitation forces, acting on the internal surface of the case due to bearing reactions and pressure forces, have been obtained from the LP model. In this sense the model is globally a hybrid LP/FE model. The model has been assessed using experiments: the experimental accelerations measured during run-up tests have been compared with the simulated accelerations coming from the FE/LP model. Finally the assessed model has been used in order to identify the effects of design parameters in terms of case vibrations.

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