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1

Dynamic finite element analysis of rotor-shaft fastening into a heavy precise lathe

Dounar Stanislau, Jakubowski Andrzej

Zeszyty Naukowe Akademii Morskiej w Szczecinie

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2021

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nr 66 (138)

37--45

EN

The results of finite element analysis of large machined rotor fastened into heavy precise lathe are reported. Many design changes are simulated to improve the dynamic rigidity of the machining. Three radial eigenmodes detrimental to the accuracy were revealed: rotor-stock bending at 17.7 Hz (“half-wave”), rotor-lathe bending at 36.1 Hz (“full-wave”), and “support rocking” at 68.1 Hz. The frequency response functions and dynamic rigidities were evaluated. Three compliance issues were revealed: angular flexibility of the spindle console, low stiffness of the lathe bed (with boots), and an excessively slender tailstock. It is proposed to transform the spindle chuck into a table with additional hydrostatic backing, fill the bed cavities with concrete, and redesign the tailstock as a counter-spindle unit. This will decrease the amplitude of the main rotor resonance by 6.3 times and upshift the frequency near two-fold from 17.7 to 35 Hz. The renovated lathe should be able to machine a rotor without a lunette system or overriding the main resonant frequency.

2

Finite element analysis of the impact of the properties of dental wedge materials on functional features

Czerwiński M., Żmudzki J., Kwieciński K., Kowalczyk M.

Archives of Materials Science and Engineering

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2021

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Vol. 112, nr 1

32--41

EN

Purpose: Defect of the interproximal wall of the tooth is filled with use the shaped matrix and wedge which seals bottom margin during filling. Better fit of the wedge and equalization of the pressure forces on the matrix is achieved by the compliance of the wedge structure through cuts and perforations and the use of silicone materials and unidirectionally expanded polytetrafluoroethylene (ePTFE). The work presents a methodology for model studies of the mechanics of dental wedges in order to evaluate and compare the impact of wedge materials on functional features. The hypothesis of the work was that the mechanical properties of ePTFE determine the effectiveness of the dental wedge. Design/methodology/approach: Effect of modulus of elasticity and friction coefficient of wedge and matrix materials on the functional features of the wedge was studied on the way Finite Element Analysis (FEA). Simulation included contact sliding between wedge and matrix what was simulated in nonlinear large displacements regime. The sealing evaluation criterion was the pressure distribution between the wedge and matrix below the lower edge of the defect. Displacement values were the criterion for the loss of convexity as a result of matrix deformation. Findings: The material for the wedge should be characterized by a low coefficient of friction, low elasticity (ensuring high compliance of the wedge) and at the same time the ability to large permanent deformations, which allows for plastic shaping of the matrix from the side of the defect in order to achieve the required wall convexity and the tangent point. Research limitations/implications: Results show tendency of phenomena in limitation to model simplification of the interdental gap and the ideal adhesion of the matrix to the tooth and linear elasticity of materials. Practical implications: The material that best meets the requirements is unidirectionally expanded polytetrafluoroethylene, which has one of the lowest coefficients of friction and very high plasticity necessary to shape the matrix from the inside of the cavity. Originality/value: Methodology of model study and criteria of functional characteristics of dental wedge was presented.

3

Modelling and analysis of five-phase permanent magnet synchronous motor in machine variables

Umoh Gideon, Ogbuka Cosmas, Obe Emeka

Przegląd Elektrotechniczny

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2020

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R. 96, nr 1

87--92

EN

The direct-phase variables (DPV) model of a five-phase permanent magnet synchronous motor is developed, presenting a more detailed set of equations for the motor in machine variables. The developed DPV model is simulated in MATLAB/Simulink to observe the characteristics response of speed and torque. The results were directly compared with a similar model developed in Ansys Maxwell Finite Element Analysis (FEA) software. Comparable results were obtained thereby validating the accuracy of the DPV Model.

PL

Przedstawiono model pięciofazowego silnika synchronicznego z magnesami trwałymi. Model analizowano z wykorzystaniem programów Matlab/Simulink. Wyniki są zbliżone do modeloewania ptrzy wykorzystaniu programu Ansys Maxwell Finite Element Analysis (FEA).

4

Stress field determination based on digital image correlation results

Musial Sandra, Nowak Marcin, Maj Michał

Archives of Civil and Mechanical Engineering

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2019

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Vol. 19, no. 4

1183--1193

EN

The aim of this work was to determine the stress distribution during plastic deformation, based on the displacement field obtained using the digital image correlation (DIC) method. To achieve stress distribution, the experimentally measured displacement gradient and the elastoplastic material model with isotropic hardening were used. The proposed approach was implemented in the ThermoCorr program. The developed procedure was used to determine stress fields for uniaxial tension and simple shear processes, carried out on samples made of austenitic steel 304L. Both material parameters, such as the Young's modulus, Poisson's ratio, yield stress, and parameters of the hardening curve, were acquired experimentally. The macroscopic force obtained from the DIC-based stresses and its finite element analysis (FEA) equivalent were compared with that measured during the experi- ment. It was shown that the DIC-based approach gives more accurate results with respect to FEA, especially for a simple shear test, where FEA significantly overestimates the value of experimentally obtained macroscopic force.

5

Experimental and numerical investigation of the deep drawing process for an automobile panel and prediction of appropriate amount of parameters by multi-layer neural network

Najafabadi S. S., Anaraki A. T., Moradi M.

Journal of Theoretical and Applied Mechanics

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2017

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Vol. 55 nr 2

707--718

EN

In this paper, the deep drawing process of an automobile panel in order to select the appropriate amount of parameters has been investigated. The parameters include friction between the blank and die, blank width and length, blank thickness and gap between the blank and blank-holder. A multi-layer artificial neural network (ANN) trained by finite element analyses (FEA) is applied in order to improve forming parameters and achieve a better quality. As the FEA results are used to train the ANN, the FEA results have been verified by three experiments. Finally, an appropriate amount of each parameter is predicted by the trained ANN and a FEA has been done based on the ANN prediction to evaluate the accuracy of the trained ANN. Moreover, it is shown that the ANN could predict results within a 10 percent error. In addition, the proposed method for prediction of the appropriate parameters (ANN) is confirmed by comparing with the Taguchi design of experiment prediction. It is also shown that the model obtained by the former method has lower errors than the latter one. In this study, the Taguchi model is used to evaluate the effect of parameters on tearing and wrinkling. Based on the Taguchi design of experiment, while the blank length is the most effective parameter on tearing, the maximum height of wrinkles on flanged parts mainly depends on the blank thickness.

6

Finite element analysis of influence of flank wear evolution on forces in orthogonal cutting of 42CrMo4 steel

Madajewski M., Nowakowski Z.

Archives of Mechanical Technology and Materials

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2017

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Vol. 37

58--64

EN

This paper presents analysis of flank wear influence on forces in orthogonal turning of 42CrMo4 steel and evaluates capacity of finite element model to provide such force values. Data about magnitude of feed and cutting force were obtained from measurements with force tensiometer in experimental test as well as from finite element analysis of chip formation process in ABAQUS/Explicit software. For studies an insert with complex rake face was selected and flank wear was simulated by grinding operation on its flank face. The aim of grinding inset surface was to obtain even flat wear along cutting edge, which after the measurement could be modeled with CAD program and applied in FE analysis for selected range of wear width. By comparing both sets of force values as function of flank wear in given cutting conditions FEA model was validated and it was established that it can be applied to analyze other physical aspects of machining. Force analysis found that progression of wear causes increase in cutting force magnitude and steep boost to feed force magnitude. Analysis of Fc/Ff force ratio revealed that flank wear has significant impact on resultant force in orthogonal cutting and magnitude of this force components in cutting and feed direction. Surge in force values can result in transfer of substantial loads to machine-tool interface.

7

A sensitivity analysis on the influence of the external constraints on the dynamic behaviour of a low pollutant emissions aircraft combustor-rig

Amoroso F., Fenza A. de, Petrone G., Pecora R.

Archive of Mechanical Engineering

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2016

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Vol. LXIII, nr 3

435--454

EN

The need to reduce pollutant emissions leads the engineers to design new aeronautic combustors characterized by lean burn at relatively low temperatures. This requirement can easily cause flame instability phenomena and consequent pressure pulsations which may seriously damage combustor’s structure and/or compromise its fatigue life. Hence the need to study the combustor’s structural dynamics and the interaction between elastic, thermal and acoustic phenomena. Finite element method represent a largely used and fairly reliable tool to address these studies; on the other hand, the idealization process may bring to results quite far from the reality whereas too simplifying assumptions are made. Constraints modelling represent a key-issue for all dynamic FE analyses; a wrong simulation of the constraints may indeed compromise entire analyses although running on very accurate and mesh-refined structural models. In this paper, a probabilistic approach to characterize the influence of external constraints on the modal behaviour of an aircraft combustor-rig is presented. The finite element model validation was performed at first by comparing numerical and experimental results for the free-free condition (no constraints). Once the model was validated, the effect of constraints elasticity on natural frequencies was investigated by means of a probabilistic design simulation (PDS); referring to a specific tool developed in the ANSYS®software, a preliminary statistical analysis was at performed via Monte-Carlo Simulation (MCS) method. The results were then correlated with the experimental ones via Response Surface Method (RSM).

PL

Potrzeba redukcji zanieczyszczeń stawia wobec inżynierów wymaganie projektowania samolotowych komór spalania, które charakteryzują się ubogim spalaniem przy relatywnie niskich temperaturach. W tych warunkach mogą łatwo powstawać zjawiska niestabilności płomienia i wynikające stąd pulsacje ciśnienia, które mogą poważnie uszkodzić strukturę komory spalania lub/i zmniejszyć jej trwałość zmęczeniową. Wynika stąd potrzeba studiów nad dynamiką strukturalną komory spalania i interakcjami między zjawiskami termicznymi i akustycznymi. Metoda elementów skończonych jest narzędziem dość niezawodnym i powszechnie stosowanym, odpowiednim do takich studiów. Z drugiej strony, proces idealizacji może prowadzić do wyników, które są bardzo odległe od rzeczywistości, jeżeli w założeniach przyjęto nadmierne uproszczenia. Modelowanie więzów jest sprawą kluczową dla wszystkich analiz dynamicznych metodą elementów skończonych. Błędna symulacja więzów może istotnie zagrozić całej analizie, nawet gdy korzysta się w niej z bardzo dokładnych modeli strukturalnych o udoskonalonej siatce. W artykule zaprezentowano podejście probabilistyczne by scharakteryzować wpływ więzów zewnętrznych na właściwości modalne zespołu samolotowej komory spalania. Najpierw przeprowadzono walidację modelu elementów skończonych drogą porównania wyników doświadczalnych i obliczeniowych w warunkach swobodnych (bez więzów). Gdy potwierdzono prawidłowość modelu, zbadano wpływ sprężystości więzów na częstotliwości drgań własnych stosując metodę probabilistycznego projektowania symulacji (PDS). Korzystając ze specjalnego narzędzia opracowanego w oprogramowaniu ANSYS, wykonano wstępną analizę statystyczną metodą symulacji Monte Carlo (MCS). Jej wyniki skorelowano następnie z wynikami doświadczalnymi stosując metodę powierzchni odpowiedzi (RSM).

8

Axial-Flux Synchronous Machines Compared with Different Stator Structures for Use in Working

Huner E., Akuner C.

Przegląd Elektrotechniczny

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2012

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R. 88, nr 11a

174-177

EN

In this study, three different stator topologies were investigated and compared utilizing 3D magnetic analysis, analytical calculations, and experimental studies. These stator structures are torus iron core: There have been far fewer studies based on slotless stator torus axial-flux permanent magnets (TAFPM-NS). Comparisons of simulated and measured values on prototype machines are also presented to validate the analyses.

PL

W artykule przedstawiono wyniki prac dotyczących bezżłobkowego torusa stojana maszyny synchronicznej z magnesami trwałymi o strumieniu osiowym (ang. torus axial-flux permanent machine - TAFPM-NS). Materiał przedstawia badania i porównanie trzech typów stojana, na podstawie analizy magnetycznej 3-D oraz fazy eksperymentalnej.

9

Model połączenia skurczowo-rozprężnego tulei z nieprzelotowym cylindrem silnika spalinowego

Michalski J., Woś P.

Silniki Spalinowe

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2011

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R. 50, nr 3

PL

W artykule przedstawiono rozwiązanie analityczne i numeryczne połączenia skurczowo-rozprężnego tulei cylindrowej z kadłubem - nieprzelotowym cylindrem silnika spalinowego chłodzonego powietrzem FRANKLIN PZL-F 4A-235-B31. Rozpatrywano połączenia dwu wariantów tulei cylindrowych o odmiennej grubości ścianki. Analizowano płaski stan naprężenia z teorii sprężystości, tzw. zadanie Lame'go, metodą analityczną. Wyniki porównano z obliczeniami numerycznymi metodą elementów skończonych w systemie PATRAN. Rozpatrywano model osiowo-symetryczny i płaski z elementami kontaktowymi płaskimi. Charakterystyki materiałowe dla tulei z żeliwa szarego i kadłuba cylindra z żaroodpornego stopu aluminium wyznaczono doświadczalnie. W wyniku obliczeń uzyskano stan wytężenia tulei cylindrowej i kadłuba cylindra oraz dyslokacji tych elementów.

EN

The analytical and numerical solving of compression-expansion joint of the cylinder liner with the blind cylinder case for the air-cooled engine FRANKLIN PZL-F 4A-235-B31 is presented. Two cylinder liners varied with wall thickness were taken into consideration. A planar stress state was analytically analyzed by Lame theory of elasticity. The results were compared with numerical solution, which has been done by FEA using PATRAN system. An axial-symmetrical and planar model with flat contact elements was analyzed. Material characteristics for the liners made of grey cast iron and for cylinder case made of heat-resisting aluminum alloy were determined experimentally. As a result, the stress and dislocations patterns for these elements were obtained.

10

Assessment of Torques for a Permanent Magnet Brushless DC Motor Using FEA

Petkovska L., Cvetkovski G.

Przegląd Elektrotechniczny

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2011

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R. 87, nr 12b

132--136

EN

This paper deals with magnetic field calculations and FE model-based prediction of torques in a PMBLDC motor. As a function of the rotor position, the torque produced by these machines has a pulsating component in addition to the dc component. This pulsating torque, according to the motor drive, has a fundamental frequency corresponding to six pulses per electrical revolution of the motor. The finite element analysis (FEA) has been employed to assess electromagnetic torque and cogging torque waveforms. The torque ripple in dependence of the switching angle for the control device is thoroughly investigated.

PL

Artykuł przedstawia obliczenia pola magnetycznego i predykcję momentu, bazujące na technice elementów skończonych, dla trójfazowych bezszczotkowych silnikach prądu stałego z magnesami trwałymi. Funkcją pozycji wirnika jest składnik pulsacyjny w momencie produkowanym przez te maszyny. Moment pulsacyjny, zgodnie z napędem silnika, posiada harmoniczną podstawową korespondującą od sześciu pulsów na jeden obrót wirnika. Metoda elementów skończonych została użyta do oszacowania momentu elektromagnetycznego oraz momentu żłobkowego. Zakłócenia momentu w zależności od kąta włączenia są szczegółowo badane.