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1

Parallel anisotropic mesh refinement with dynamic load balancing for transonic flow simulations

Gepner S., Majewski J., Rokicki J.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2017

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Vol. 65, nr 2

195--207

EN

The present paper discusses an effective adaptive methods suited for use in parallel environment. An in-house, parallel flow solver based on the residual distribution method is used for the solution of flow problems. Simulation is parallelized based on the domain decomposition approach. Adaptive changes to the mesh are achieved by two distinctive techniques. Mesh refinement is performed by dividing element edges and a subsequent application of pre defined splitting templates. Mesh regularization and derefinement is achieved through topology conserving node movement (r-adaptivity). Parallel implementations of an adaptive use the dynamic load balancing technique.

2

Application of grid convergence index in FE computation

Kwaśniewski L.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2013

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Vol. 61, nr 1

123-128

EN

This paper presents an application of the grid convergence index (GCI) concept based on the Richardson extrapolation to a selected simple problem of a cantilever beam loaded with vertical forces at the tip end. The GCI method, popular in computational fluid dynamics, has been recently recommended for finite element (FE) applications in solid and structural mechanics. Based on the results obtained usually for three meshes, the GCI method enables one to determine, in an objective manner, the order of convergence to estimate the asymptotic solution and the bounds for discretization error. The example shows that the characteristics of the convergence depend on the selection of the quantity of interest, which can be local or a global functional such as the deflection considered here. The results differ for different FE formulations, and the difference is bigger when the nonlinearities (e.g., due to plastic response) are taken into account.

3

Generation of dedicated finite element meshes for multiscale applications with Delaunay triangulation and adaptive finite element - cellular automata algorithms

Madej L., Krużel P., Cybułka P., Perzyński K., Banaś B.

Computer Methods in Materials Science

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2012

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Vol. 12, No. 2

85-96

EN

The main aim of the work is development and comparison of algorithms for mesh creation that can be further used to investigate material behavior under loading conditions, on the basis of digital material representation. Particular attention is put on development of conforming meshes for two-phase materials. Two approaches are investigated within the present work. The first is based on mesh refinement along particular microstructure features. The second incorporates cellular automata phase transformation model into the FE element adaptation technique. Description of the two approaches and example of application of the obtained meshes to analysis of the multiscale material behavior under plastic deformation condition are presented.

PL

Głównym celem pracy jest opracowanie i porównanie algorytmów generowania siatek, elementów skończonych, które można wykorzystać do badania zachowania materiału w warunkach odkształcenia z wykorzystanie idei cyfrowej reprezentacji materiału. W pracy szczególna uwaga została położona na odwzorowanie stopniem zagęszczenia elementów morfologii materiałów dwufazowych. W tym celu wykorzystano dwa różne algorytmy. Pierwszy oparty jest na utworzeniu siatki poprzez triangulacje Delaunay przy jednoczesnym jej zagęszczeniu wzdłuż poszczególnych elementów mikrostruktury. Drugi obejmuje wykorzystanie modelu przemiany fazowej opracowanego na bazie metody automatów komórkowych i sprzęgnięcie go z algorytmami adaptacji siatki podczas rozwiązania MES zagadnienia liniowej sprężystości. Opis w/w algorytmów oraz przykład zastosowania uzyskanych siatek do wieloskalowej analizy zachowania się mikrostruktury w warunkach odkształcenia plastycznego jest zamieszczony w ramach niniejszej pracy.

4

Fretting wear damage-I: numerical study of composite steel sheets reinforced with TiB2

Ayari F., Bayraktar E.

Archives of Materials Science and Engineering

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2011

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Vol. 51, nr 1

48-54

EN

Purpose: of this paper is based on the damage analysis by fretting wearing occurred on the composite steel sheets reinforced with TiB2 ceramic particles. There is a real lack to find a reliable data and detail research in literature that makes the purpose of this manuscript. Design/methodology/approach: Fretting is a surface degradation process in which removal of material is induced by small amplitude oscillatory movement between contacting components, such as flexible coupling joint structures etc. The main parameters affecting fretting wear are reported to be normal load, slip amplitude, frequency of the oscillatory movement, contact geometry, surface roughness and material properties. In this study, a finite element-based method is presented for simulating the contact of a rigid cylinder on flat fretting wear for the composite steel sheets reinforced with TiB2 ceramic particles. Findings: The general purpose commercial code ABAQUS was employed; this model can be used to facilitate generalization of the present approach to more complex applications. In this study a particular mesh technique was used to optimize the computation time, especially when dynamic analysis is used. In fact, two-dimensional, four-node, plane strain (linear) elements are employed throughout. The mesh (element size) in the contact area is very fine to capture the complicated variation of the surface and subsurface stresses and relative slip. The contact surface is constituted with a rigid hard steel cylinder material and a flat plate of composite steel sheets reinforced with TiB2 ceramic particles. Practical implications: This manuscript concerns a typical contact with the cylindrical plan geometry as it models the major problems and also stress distribution due to the contact was well defined. Our assembly is then, composed with a cylindrical contact with a plan substrate. An elastic - plastic analysis of fretting stress using a finite element ABAQUS is enhanced. The cylindrical pad is made of a rigid material and a flat plate the composite steel sheets reinforced with TiB2 ceramic particles. A bilinear elastic - plastic isotropic hardening model with a von Mises yield surface is employed to characterize the material behaviour of these composite steel sheets reinforced with TiB2 ceramic particles.This manuscript give a real and practical usage as a friendship notice concerning this subject. Originality/value: is very well shown that this model is firstly verified through comparison with an analytical elastic solution. Various parameters, such as friction coefficient, the normal force applied on the top of the pad, tangential force applied to the left side of the pad, and bulk tension applied on the right edge of the substrate are adopted to study the influences of these parameters on fretting stresses to understand the implication and importance of elastic-plastic analysis in fretting fatigue experiments. Keywords: Fretting wear; Slip; Contact; FEM; Mesh refinement; Composite steel sheets; Reinforcement of TIB2

5

Mesh refinement and timestep selection in numerical finite element simulations of solidification

Nagórka A.

Archiwum Odlewnictwa

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2004

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R. 4, nr 14

319-324

EN

An application of adaptive mesh refinement and automatic timestep selection in finite element simulations of solidification is presented. Adaptive algorithms are based on quantitative information on the accuracy of the results given by estimators of the error of spatial and temporal discretisations. Substantial reduction of computation time possible thanks to adaptivity is reported.

PL

Zaprezentowano zastosowanie adaptacyjnego zagęszczania siatki i automatycznego doboru kroku czasowego w symulacjach komputerowych krzepnięcia metodą elementów skończonych. Algorytmy adaptacyjne oparte są na ilościowej informacji o dokładności rozwiązania dawanej przez estymatory błędu dyskretyzacji przestrzennej i czasowej. Pokazano znaczne skrócenie czasu obliczeń możliwe dzięki adaptacji.