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1

Numerical analysis of geometrical parameters effect on contact zone under fretting fatigue loading

Ikhlef Chaouch Mohamed, Baltach Abdelghani, Benhamena Ali

Advances in Materials Science

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2022

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Vol. 22, nr 4(74)

5--20

EN

The fatigue process under fretting conditions is characterized by small oscillatory movements due to vibrating or cyclic loads between two surfaces in contact. Two phenomena can arise as a consequence: the surface wear of the bodies in contact, giving rise to the so-called fretting wear. The second phenomenon concerns crack nucleation in the contact region, causing a reduction in the fatigue strength of the component subjected to cyclic loading. This process is called “fretting fatigue”. In the present study, finite element models (2D-FEM) are provided to demonstrate the effect of pad radius on the contact parameters such as: contact pressure, shear traction, stresses, sliding, size of contact line and crack nucleation and its location along the contact line of aeronautical Al2024 alloy under fretting fatigue loading. Six numerical models are utilized to describe the effect of changing pad radii on contact stresses and damage of crack nucleation. The Ruiz parameter criterion should be used to predict the location of crack initiation in the contact zone. Comparison of the finite element results shows that there is a good agreement between the numerical modeling predictions with those analytical results. The stress field, relative slip, and damage parameters in fretting fatigue loading were highlighted. The pad radius substantially affects the distribution of contact parameters. Particular attention must be taken into consideration to this variable when analyzing the structure in fretting fatigue.

2

General directions in contact modelling development

Maciolka Pawel, Jedrzejewski Jerzy

Journal of Machine Engineering

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2019

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Vol. 19, No. 4

91--109

EN

This paper presents a survey of works, selected from the period of the last twenty years, on deformations in the contact between rough surfaces. All the selected works use FEM. They deal with the modelling of individual contact asperities or the use of experiment to verify contact models. First, research directions connected with the modelling of single asperities, whose shape is usually approximated with that of a hemisphere or a half cylinder, are presented. Section 3 discusses research directions concerning models which include the layer under asperities, and models for small contact surfaces (about 1 mm2). Section 4 reviews directions in contact modelling which takes into account neighbouring asperities and laterally loaded asperities. Section 5 discusses directions in the development of models and experiments used or suitable for verifying models. Finally, conclusions concerning accurate contact deformation modelling are presented.

3

Local Phenomena During Riveting Process

Kaniowski J., Wronicz W.

Fatigue of Aircraft Structures

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2013

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Iss. 5

66--78

EN

The paper presents experimental and numerical study of the local phenomena during the riveting process. It is commonly accepted that technological factors of the riveting process has a strong influence on the fatigue life of riveted joints. The authors analysed the papers concerned the experimental researches of the riveting force influence on fatigue life. The magnitude of the life increase caused by the riveting force increase suggests the authors that this is not only the result of beneficial stress system but the change of the joint formation mechanism has taken place. This was an inspiration to undertake more detailed researches of the riveting process. The strain progress during the riveting process has been experimentally investigated for four types of aluminium rivets used in airframes. Measurements confirm very high strains near the driven head. For some types of rivets the reversal strain signal has been recorded. Several FE model has been use to investigate the riveting process. The axisymmetric and solid models were used. The agreement of experimental and numerical results in some cases were good, in other cases the numerical models demand further development. In any calculations, the reversal strain effect has not been obtained, This suggest that it is result of the phenomenon which has not been taken into account in numerical modelling. The working hypothesis has been assumed that during the riveting process adhesive joints (called cold welding) were formed and destroyed during the process, what was the reason of the observed reversal strain signal. The authors are going to continue this investigation.

4

An influence of auditory chain components’ stiffness on vibrations characteristics measured by a finite-element model of the middle ear structure

Samborski S., Rusinek R., Szymański M.

Vibrations in Physical Systems

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2012

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Vol. 25

347--353

EN

The problem of modelling of middle ear auditory chain functioning is still very difficult to be made precisely in comparison with the real ossicles’ behaviour observed experimentally. The main reason for this is geometrical complexity and a number of material characteristics of the ossicles themselves. Here, FEM is engaged to model human middle ear work because this method allows for reconfiguring of complex auditory chain geometry, various material models etc. and provides good accuracy.

5

Modelowanie metodą elementów skończonych połączeń centralna struktura nośna - cewki w reaktorze syntezy jądrowej Wendelstein 7X

Krzesiński G., Marek P., Zagrajek T., Borkowski P.

Górnictwo Odkrywkowe

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2010

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R. 51, nr 3

21-24

PL

Celem pracy było opracowanie parametrycznych modeli metody elementów skończonych kompletu złożonych połączeń śrubowych reaktora syntezy jądrowej (stellatora) montowanego w Greifswaldzie w Niemczech [1]. Wybrane wymiary modeli, właściwości materiałowe, warunki oddziaływań kontaktowych, obciążenia, a także prezentacja wyników zdefiniowane zostały w sposób parametryczny. Takie podejście pozwala na szybka analizę porównawczą różnych alternatywnych modyfikacji połączeń. Opracowane modele są wykorzystywane dla określenia końcowych rozwiązań projektowych, sił naciągu śrub, akceptowalnych tolerancji wykonania i klinów stabilizujących oraz innych detali połączeń.

EN

Che aim of this work was to develop FE parametric models of the set of complex bolted connections of the W7X stellator assembleded in Greifswald, Germany [1]. In the models the selected dimensions, materiałproperties, contact conditions, loads as well as results presentation are defined in a parametric way. This allows for a ąuick variant analyses of many modification alternatives. The devełoped models are usedfor the definition of the finał connections design: bolts preloadforces, acceptable tok nmces and wedges stabilizing the connections etc.

6

Analysis of uncertainties in MEMS and their influence on dynamic properties

Uhl T., Martowicz A., Codreanu I., Klepka A.

Archives of Mechanics

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2009

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Vol. 61, nr 5

349-370

EN

An application of uncertainty analysis of microelectromechanical resonator is presented. A number of different uncertain parameters have been considered, connected both to geometric characteristics and material property. Sensitivity analysis has been carried out in order to study the influence of each input uncertain parameter on the chosen dynamic characteristics. The propagation of given uncertainties into the variation of studied output parameter has been evaluated by means of the Monte Carlo simulation, the vertex method and genetic algorithms. Finite element model of microresonator has been elaborated. It has taken into account the phenomenon of viscous damping coming from the presence of surrounding air as well as the in?uence of constant electrostatic field.

7

Bump-type foil bearing, 2D finite element model

Rządkowski R, Kicinski J, Drewczynski M, Żywica G

Zeszyty Naukowe. Cieplne Maszyny Przepływowe - Turbomachinery / Politechnika Łódzka

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2008

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nr 133

309--316

EN

Gas foil bearing technology has made significant progress during the last 30 years. Foil bearings fulfill most of the requirements of novel oil-free turbomachinery. Numerical calculations were conducted to determine the structural stiffness of commercially available bump-type foil bearings. A 2D FE model of foil bearing was prepared. The top foil deflections versus applied force were calculated numerically. The numerical results were compared with experimental results.

8

An overview of selected plate and shell FE models with graphic presentation of governing relations

Radwańska M.

Computer Assisted Mechanics and Engineering Sciences

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2007

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Vol. 14, No. 3

431-456

EN

A survey of three forms (strong, weak and variational) of mathematical models is presented using expressive diagrams [1,2]. The primary and intermediate variables, governing field equations, constraint equations and variables specified by boundary conditions are components of the graphic representation of various FE (finite element) formulations. The attention is focused on linearly elastic plate element QUAD for Mindlin–Reissner theory and shell elements EAS4-ANS, EAS7-ANS based on CBRST (Continuum Based Resultant Shell Theory). In both cases the mixed FE models with the EAS (enhanced assumed strain) and ANS (assumed natural strain) concepts are used.

9

Generation of a finite element model of the thoracolumbar spine

Tyndyk M. A., Barron V., McHugh P. E., O'Mahoney D.

Acta of Bioengineering and Biomechanics

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2007

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Vol. 9, nr 1

35-46

EN

The goal of this study was to generate a realistic 3D FE model of the seven level thoracolumbar spine. This research focused on the development of a robust and efficient procedure for generating anatomical 3D FE models, directly from a series of medical images, i.e., CT data. A complex model of the spine was created by combining two different modelling approaches, namely the CAD and STL-CAD methods. In addition, the entire meshing procedure for the vertebrae was significantly speeded up by combining 3D tetrahedral elements with brick elements, relative to conventional mapped mesh generation procedures. The resulting model generation method allowed for flexibility in element choice and in element type combinations. The model was subjected to various compressive loads to asses the overall behaviour of the spine. This case study was performed to illustrate the usefulness of the FE model. In the authors’ opinion, the model presented is an important tool in computational spine research as it can provide general information on spinal behaviour under various loading conditions whether healthy, diseased or damaged.

10

Numeryczne obliczenia trwałości zmęczeniowej głównego węzła mocowania skrzydła samolotu wojskowego

Kurdelski M., Baraniecki R., Leski A.

Biuletyn Wojskowej Akademii Technicznej

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2006

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Vol. 55, nr 4

113-125

PL

Celem pracy było oszacowanie trwałości zmęczeniowej węzłów siłowych skrzydła samolotu Su-22. Powyższy cel zrealizowano, wykonując kompleksowe badania obejmujące między innymi analizę profilu eksploatacji samolotów, pomiary tensometryczne podczas lotów oraz modelowanie numeryczne. W niniejszej pracy przedstawiono zarys działań realizowanych w poszczególnych fazach badań. Opisano zarówno stosowane metody obliczeniowe, jak i sprzęt pomiarowy. Obliczenia trwałości wykonano metodą krzywej S-N na podstawie rzeczywistego widma obciążeń, stanu naprężenia wyznaczonego podczas obliczeń numerycznych.

EN

Assessment of the fatigue life of the Su-22 wing-root joint was rhe purpose of the work. Numerous tasks have been carried out, e.g., operational profile analysis, flight tests, stress measurement, as well as numerical calculations. The general algorithm of this complex work was presented in this paper. The applied methods and instrumentation were described. Fatigue life calculations was carried out using idea of S-N safe curve based on the real load spectrum and on the stress distribution calculated by meas of FE technique.

11

A coupled three-phase FE-model for dewatering of soils by means of compressed air

Oettel G., Stark R.F., Hofstetter G.

Computer Assisted Mechanics and Engineering Sciences

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2003

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Vol. 10, No. 1

1-22

EN

A coupled three-phase soil model, consisting of a deformable soil skeleton and the fluid phases water and compressed air, applicable for tunnelling below the ground-water table by means of compressed air, is presented. In this model interactions of the flow of the fluids in the soil with the deformations of the soil skeleton are taken into account in a physically consistent manner. The theoretical background and the implementation of the model into a finite element code are briefly addressed. Several applications dealing with the numerical simulation of laboratory tests and a full-scale in-situ experiment are discussed. These experiments focus on the flow of (compressed) air in dry as well as semi-saturated soil.

12

Comparison of FEM structural analysis and strain gauge measurements of a deck crane

Konieczny L., Litwinienko G., Rogalewski E., Besler M.

Polish Maritime Research

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1999

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nr 5

6-11

EN

A new universal 40 t deck crane for bulk carriers was constructed by the Towimor S.A., Toruń, the main Polish supplier of deck cranes and deck machinery [1]. Strain gauge measurements of the crane were performed during the stands tests at the factory. After the tests a finite element analysis of the crane was carried out to provide additinal detail information for checking accuracy of the numerical modelling in view of improving the applied FE model. In this study application of the FE method played a role independent of the experiments. Comparision of the results obtained from the two methods made it possible to improve the FE model and support the experimental results.