Wyniki wyszukiwania - BazTech

1

Influence of ultrasonic vibration-assisted cutting on ploughing effect in cutting Ti6Al4V

Chen Feiyang, Wang Dazhong, Wu Shujing

Archives of Civil and Mechanical Engineering

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2021

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Vol. 21, no. 2

55--73

EN

In this study, the finite element method (FEM) is used to study the ploughing effect of ultrasonic vibration-assisted cutting Ti6Al4V. Due to the existence of the cutting edge radius of the tool, there will be a ploughing area in the cutting of Ti6Al4V. The ploughing area is an area where the stress state is very complex in the cutting process. The ploughing force and temperature of the ploughing area are important factors that affect the machined surface quality and tool wear. The main research of this paper includes the establishment of ploughing force, temperature and dynamic friction coefficient model of the ploughing area, and the correctness of the analysis model is verified by using the finite element method. Then, by changing the cutting conditions, the influence of changing the cutting parameters on the ploughing effect is discussed. The results show that the analysis model can be used to monitor the ploughing force and ploughing area temperature, and ultrasonic vibration-assisted cutting can significantly reduce the ploughing force and ploughing area temperature, reducing tool wear and plastic deformation of the machined surface.

2

The analysis of the influence of the plane coils geometry configuration on the efficiency of WPT system

Stankiewicz Jacek Maciej

Przegląd Elektrotechniczny

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2020

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R. 96, nr 10

174--178

EN

The article presents a method and results for numerical and analytical analysis of Wireless Power Transfer (WPT) system consisting of transmitting and receiving plane coils. In the analysis took into account different variants of the WPT system geometry (number of turns, distance between the transmitting-receiving coils). The influence of variable system geometry and the frequency on system efficiency was analysed. The Finite Element Method (FEM) with the using antiperiodicity boundary conditions for the analysis was used. The results obtained by numerical and analytical method indicate at which system parameters wireless energy transfer is possible.

PL

W artykule przedstawiono metody i wyniki analizy numerycznej oraz analitycznej układu Wireless Power Transfer (WPT) złożonego z cewek płaskich (nadawczych i odbiorczych). W analizie uwzględniono różne warianty geometrii układu WPT (liczba zwojów, odległość między cewkami). Analizowano wpływ geometrii układu oraz częstotliwości na sprawność układu. Do analizy wykorzystano metodę elementów skończonych (FEM) z zastosowaniem aperiodycznych warunków brzegowych. Otrzymane wyniki wskazują, przy jakich parametrach układu możliwy jest bezprzewodowy transfer energii.

3

Thermal analysis of Double Stator Switched Reluctance Machine (DSSRM) with and without a squirrel cage rotor

Abbasian M., Jalali H.

Archives of Electrical Engineering

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2017

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Vol. 66, nr 1

189--198

EN

Double Stator Switched Reluctance Machine (DSSRM) is a novel switched reluctance machine with limited information about its heat distribution and dissipation. This paper presents a two dimensional (2-D) thermal analysis of Double Stator Switched Reluctance Machine (DSSRM) to observe actual heat distribution in the parts of the machine, using Finite Element Method (FEM). Two topologies for the rotor of DSSRM are considered, Non-Squirrel Cage Double Stator Switched Reluctance Machine (NSCDSSRM) and Squirrel Cage Double Stator Switched Reluctance Machine (SC-DSSRM). The heat distribution of these two topologies is analyzed, using Computational Fluid Dynamics (CFD). Finally the results are presented and compared.

4

The Influence of Mechanical, and Material Factors on the Biological Adaptation Processes of the Femoral Bone Implants

Jasik A., Mroczek M.

Archives of Metallurgy and Materials

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2016

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Vol. 61, iss. 1

189--194

EN

The study covers some aspects of the issue of determination of mutual connections between the mechanical and material factors, as well the biological implant adaptation processes. The main objective of the operation was adopted to develop models of cementless hip prosthesis company Fitmore Zimmer, taking into account the heterogeneity of material properties of bone tissue. These models were loaded in particular stages of the human gate and then they were used for the analysis of stress changes. The identification of the relations between the mechanical properties of osseous tissue required the conducting of computer simulations by means of the Finite Element Method (FEM).

5

Numerical analysis of stress intensity factor and T-stress in pipeline of steel P264GH submitted to loading conditions

Moustabchir H., Arbaoui J., Zitouni A., Hariri S., Dmytrakh I.

Journal of Theoretical and Applied Mechanics

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2015

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Vol. 53 nr 3

665--672

EN

Stress singularities occur at crack tips, corners and material interfaces. The stress intensity factors and T-stresses are coefficients of structural components where the active stress singular and first regular stress terms, respectively, are denoted by William’s eigen function expansion series. A finite element analysis by CASTEM 2000 have been undertaken in order to determine the evolution of the T-stress and stress intensity factor terms in mode I for an arc of pipeline specimens with an external surface crack. A stress difference method described by Moustabchir et al. (2012) are adapted and, in the following step, the volumetric method is then embedded to compute the SIFs and T-stress near the crack tip. Different crack geometries combined with different length-to-thickness ratios are examined for the T-stress and stress-intensity factor. The revisited stress difference method employed here shows to be an accurate and robust scheme for evaluating the T-stress/SIFs in an arc of the pipeline.

6

Kalibracja i walidacja procedury Mathara za pomocą Metody Elementów Skończonych

Augustyniak M., Augustyniak B., Jaworski M., Mężyk D.

Energetyka

|

2015

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nr 1

21--26

PL

Metoda pomiaru naprężeń powierzchniowych przy pomocy rozet tensometrycznych i kontrolowanych odwiertów (metoda otworkowa) jest stosowana powszechnie w odniesieniu do stali izotropowych oraz silnie anizotropowych laminatów, natomiast nie została rozpoznana jej stosowalność do umiarkowanie anizotropowych stopów metali. W artykule opisano odniesienie wyników pomiarów wykonanych na płytach ze stali duplex do modelu numerycznego MES oraz wzorów normatywnych (norma E837). Obserwowane różnice między wynikami doświadczalnymi a numerycznymi mogą wynikać z przybliżonych stałych kalibracyjnych we wzorze konstytutywnym, a także niedoskonałości geometrycznej układu pomiarowego. Nieregularność geometrii – skręcenie próbki względem głównej osi – okazuje się istotnie wpływać na odkształcenia ścinające, wprowadzając do układu dodatkowe naprężenia. Iteracyjne zastosowanie obliczeń MES pozwala na wykazanie i ilościową korektę obu efektów. Wyznaczone są stałe kalibracyjne dla rozety niestandardowej oraz wielkość błędu popełnianego przy stosowaniu wzorów izotropowych do materiału (stali duplex) o ortotropii modułów Young w zakresie 190-210 GPa. Stwierdza się, że realne niepewności pomiarowe znacznie przekraczają błąd związany ze stosowaniem wzorów izotropowych, stąd korekta pod kątem ortotropii rzędu 5%, jakkolwiek możliwa przy użyciu modelu MES, nie jest konieczna.

EN

The method of surface stress measuring with the help of tensometric rosettes and controlled drilling (pinhole method) is commonly used for isotropic steels and strongly anisotropic laminates whereas its applicability for moderate anisotropic metal alloys has not yet been recognized. Described is here the reference of results of measurements made on duplex steel plates to a FEM numerical model and normative patterns (E837 standard). The observed differences between experimental and numerical results can arise from approximative calibration constants in the constitutive pattern as well as from geometric imperfection of a measuring system. Geometric irregularity – sample torsion in relation to the main axis – has a significant influence on shear strains by introducing additional strains into the system. Iterative application of FEM calculations enables demonstration and quantity correction of both effects. Determined are calibration constants for a non-standard rosette as well as the magnitude of an error made when there are applied the isotropic formulae for materials (duplex steel) of the Young’s modulus ortotrophy in the range of 190-210 GPa. Ascertained is that the real measurement uncertainties considerably exceed the error connected with the application of isotropic formulae. So, the ortotrophy correction of 5%, though possible with the use of FEM model, is not necesary.

7

Effect Of Natural Convection On Directional Solidification Of Pure Metal

Skrzypczak T., Węgrzyn-Skrzypczak E., Winczek J.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 2A

835--841

EN

The paper is focused on the modeling of the directional solidification process of pure metal. During the process the solidification front is sharp in the shape of the surface separating liquid from solid in three dimensional space or a curve in 2D. The position and shape of the solid-liquid interface change according to time. The local velocity of the interface depends on the values of heat fluxes on the solid and liquid sides. Sharp interface solidification belongs to the phase transition problems which occur due to temperature changes, pressure, etc. Transition from one state to another is discontinuous from the mathematical point of view. Such process can be identified during water freezing, evaporation, melting and solidification of metals and alloys, etc. The influence of natural convection on the temperature distribution and the solid-liquid interface motion during solidification of pure copper is studied. The mathematical model of the process is based on the differential equations of heat transfer with convection, Navier-Stokes equation and the motion of the interface. This system of equations is supplemented by the appropriate initial and boundary conditions. In addition the continuity conditions at the solidification interface must be properly formulated. The solution involves the determination of the temporary temperature and velocity fields and the position of the interface. Typically, it is impossible to obtain the exact solution of such problem. The numerical model of solidification of pure copper in a closed cavity is presented, the influence of the natural convection on the phase change is investigated. Mathematical formulation of the problem is based on the Stefan problem with moving internal boundaries. The equations are spatially discretized with the use of fixed grid by means of the Finite Element Method (FEM). Front advancing technique uses the Level Set Method (LSM). Chorin’s projection method is used to solve Navier-Stokes equation. Such approach makes possible to uncouple velocities and pressure. The Petrov-Galerkin formulation is employed to stabilize numerical solutions of the equations. The results of numerical simulations in the 2D region are discussed and compared to the results obtained from the simulation where movement of the liquid phase was neglected.

PL

Praca porusza problematykę modelowania kierunkowego krzepnięcia czystego metalu. Podczas tego procesu obserwuje się formowanie ostrego frontu krzepnięcia w postaci powierzchni separującej ciecz i ciało stałe w przypadku trójwymiarowym lub krzywej w przypadku płaskim. Położenie oraz kształt interfejsu krzepnięcia zmieniają się w czasie a wartości prędkości lokalnych zależą od różnicy intensywności strumieni ciepła po stronie ciała stałego i cieczy. Krzepnięcie z ostrym frontem należy do grupy procesów z przemianami fazowymi, które warunkowane są zmianami temperatury, ciśnienia, itp. Przejście fazowe z jednego stanu w drugi ma z matematycznego punktu widzenia charakter nieciągły. Procesy tego typu można zidentyfikować podczas zamarzania wody, parowania, topnienia i krzepnięcia metali i stopów, itp. W pracy zbadano wpływ zjawiska konwekcji swobodnej na chwilowy rozkład temperatury oraz ruch granicy narastania fazy stałej podczas krzepnięcia czystej miedzi w obszarze płaskim. Model matematyczny sformułowano na bazie równań różniczkowych transportu ciepła z konwekcją, Naviera-Stokesa i ruchu frontu krzepnięcia. Układ równań uzupełniono odpowiednimi warunkami początkowymi i brzegowymi oraz warunkami ciągłości na froncie. Rozwiązanie obejmuje chwilowe rozkłady temperatury, prędkości oraz położenie granicy międzyfazowej. Sformułowanie matematyczne zagadnienia bazuje na modelu z ruchomymi granicami wewnętrznymi, czyli tzw. modelu Stefana. Równania zostały zdyskretyzowane przestrzennie z wykorzystaniem metody elementów skończonych. W modelu numerycznym wykorzystano siatkę niezmienną w czasie. Do propagacji frontu użyto metody poziomic. Do wyznaczenia prędkości w cieczy wykorzystano metodę rzutowania, która poprzez eliminację ciśnienia z równania pędu pozwala na rozprzężenie prędkości i ciśnień. Równania rozwiązano z wykorzystaniem sformułowania Petrova-Galerkina. Omówiono wyniki analizy numerycznej oraz porównano je z wynikami otrzymanymi z symulacji, w której pominięto ruch cieczy.

8

Selected properties of fem numerical models for inverse analysis of road pavement structures

Górnaś P., Pożarycki A.

Roads and Bridges - Drogi i Mosty

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2014

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Vol. 13, no. 3

203--222

PL

Biorąc pod uwagę kluczowe parametry modelu nawierzchni jezdni, opartego na metodzie elementów skończonych (MES), takie jak rodzaj, kształt siatki elementów skończonych, warunki brzegowe oraz wymiary modelu nawierzchni, przeprowadzono konfrontację uzyskanych wyników identyfikacji wartości modułów sprężystości z wynikami obliczeń dla modelu, którego równania równowagi statycznej bazują na klasycznej teorii warstw sprężystych spoczywających na półprzestrzeni sprężystej (LET). Podano warunki dla modelu MES, przy których różnica między zidentyfikowanymi wartościami modułów sprężystości względem metody LET jest mniejsza niż 10%. W większości przypadków stwierdzono również, że moduł błędu względnego dla zidentyfikowanych wartości modułów sprężystości obiema metodami zależy od głębokości usytuowania warstwy w modelu.

EN

Taking into consideration the key parameters of a FEM based pavement model, such as type, shape of mesh of finite elements, boundary conditions and dimensions, the authors compared the obtained values of elastic moduli with the results of calculations based on the classical theory of elastic layers positioned on elastic half-space (LET). The properties FEM model have been described for which the obtained difference between identified values of elastic moduli with respect to LET method is less than 10%. Moreover, in the majority of cases it has been concluded that the module of relative error of the values of elastic moduli identified with both methods depends on the depth of the layer within the model.

9

Badania zmęczeniowe kompozytowego dźwigara skrzydła motoszybowca

Orkisz M., Święch Ł., Zacharzewski J.

Eksploatacja i Niezawodność

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2012

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Vol. 14, No. 3

228-232

EN

The paper presents experimental and numerical investigation of wing's spar. Part of the spar was subjected to one step fatigue test, covering 10,000 load cycles corresponding to the oscillations of the load factor from nz min = ?3.7 to nz max = 5.7. Such test is proposed as an alternative to the full loading spectrum tests. During the experiment 3D scan was used to rapid inspection of sensitive structure's areas. Application of optical strain gauges based on a fiber Bragg's grating allowed to observe the phenomenon of local, periodical strengthening of the structure.

PL

W pracy przedstawiono badania eksperymentalne i numeryczne dźwigara skrzydła. Fragment dźwigara poddano jednostopniowemu testowi zmęczeniowemu, obejmującemu 10.000 cykli obciążeń odpowiadających oscylacjom współczynnika obciążeń od nz min= ?3.7 do nz max= 5.7. Test taki proponowany jest jako alternatywa dla próby z zastosowaniem pełnego spektrum obciążeń. W trakcie badań wykorzystano skanowanie przestrzenne, jako propozycję szybkiej metody inspekcji newralgicznych obszarów konstrukcji. Zastosowanie do pomiaru odkształceń systemu światłowodowych czujników tensometrycznych opartych na siatce Bragga'a pozwoliło na zaobserwowanie zjawiska lokalnego, okresowego umacniania struktury.

10

Finite element modelling of the cervical spinal cord injury - clinical assessment

Czyż M., Ścigała K., Będziński R., Jarmundowicz W.

Acta of Bioengineering and Biomechanics

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2012

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Vol. 14, no. 4

23-29

EN

The aim of the study was to evaluate the efficiency of Finite Element Method (FEM) modelling of the clinical cases of traumatic cervical spinal cord injury (SCI). The study population consisted of 28 patients suffering from traumatic cervical spine injury with (study group) and without (control) neurological deficits. A numerical simulation of the trauma event was performed, based on validated 3D FEM model. All the results obtained underwent statistical analysis. Statistically significant differences between both groups were found in severity of bony and neural structure damage as well as in stress and strain ratios. The highest values of tensile stress and deformation were noted in the sagittal (Y) axis. The maximum stress and strain were found in anterior spinothalamic, lateral spinothalamic and dorsal columns. It was also found that stress and strain in each segment and axis of the spinal cord model were positively correlated with the severity of the cervical spine injury (R-Spearman 0.39 to 0.64) and neurological symptoms of SCI (R-Spearman: 0.43 to 0.82). It is possible to create a clinical numerical model of the SCI with the use of FEM. The correlations between the mechanical force and neurological deficits show tendencies which require further studies based on an improved model and a greater number of patients.

11

Verification of a mathematical model of the polarimetric current sensor with single-mode fiber measurement coil based on computer simulation by Finite Element Method

Torbus S. A., Jordan A., Surma D.

Zeszyty Naukowe. Elektrotechnika / Uniwersytet Technologiczno-Przyrodniczy w Bydgoszczy

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2011

|

z. 16

17-26

EN

This article presents the verification of a mathematical model polarimetric current sensor proposed in [1]. The verification was based on computer simulation, which was based on the finite element method. Simulation model was prepared for one of the options for deployment of high voltage cables 110 kV [2]. The simulation was performed for two operating conditions of highvoltage power line - and rated the state short-circuit conditions. In addition, estimated absolute and relative error of measurement.

PL

W artykule przedstawiono weryfikację modelu matematycznego polarymetrycznego czujnika prądu w [1]. W tym celu wykorzystano symulację komputerową, opartą na metodzie elementów skończonych. Opracowany model symulacyjny dotyczył jednej z możliwych opcji rozmieszczenia przewodów na słupie linii elektroenergetycznej wysokiego napięcia 110 kV [2]. Symulacja została przeprowadzona dla dwóch stanów pracy linii wysokiego napięcia - pracy znamionowej i zwarcia. Ponadto został oszacowany błąd bezwzględny i względny pomiaru natężenia prądu za pomocą czujnika polarymetrycznego [1].

12

Computer aided seismic analyses for transformers

Płatek R., Juszkiewicz G.

Czasopismo Techniczne. Mechanika

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2011

|

R. 108, z. 4-M/2

439-447

EN

In the paper a different numerical approaches for seismic analysis of the power products have been presented. Main focus was put on typical simulation methods defined by IEEE and IEC standards. In many cases substations such as transformers are filled with oil. Standards do not provide clear information about fluid influence on power equipment during seismic event. Due to that fact some investigations related with fluid filled substations were done and summarized in this paper. Three different simulation methods were investigated: Fluid Structure Interaction (FSI) approach using FEM, CFD and code coupling software, acoustic approach and CEL (Coupled Euler Lagrange) method using Lagrange and Euler element formulation.

PL

W artykule przestawiono różne podejścia numeryczne wykorzystywane do analiz sejsmicznych transformatorów. Głównie opisane metody symulacyjne, które są wskazane przez standardy IEEE oraz IEC. Jakkolwiek w tego typie produktach mamy często do czynienia z występującą tam cieczą, np. transformatory mocy a jego wpływ nie jest jasno określony przez powyższe standardy. W związku z powyższym trzy różne podejścia numeryczne do oszacowania wpływu cieczy na strukturę w produktach mocy zostały przedstawione. Są to: podejście oparte na metodzie Fluid Structure Interaction (FSI), podejście oparte na elementach akustycznych oraz podejście oparte na równaniach Lagange oraz Eulera (Coupled Euler Lagrange).

13

Numerical model of the human cervical spinal cord - the development and validation

Czyż M., Ścigała K., Jarmundowicz W., Będziński R.

Acta of Bioengineering and Biomechanics

|

2011

|

Vol. 13, no. 4

51-58

EN

The influence of mechanical load on the extent of nervous tissue damage in the spinal cord at the time of trauma is presently incontestable. Although numerical modelling cannot fully replace physical testing, it seems to be the perfect complement to experiments in terms of the analysis of such a complex phenomenon as traumatic spinal cord injury. Previous numerical models of the human cervical spinal cord have been limited by several factors: two-dimensional modelling, spinal cord geometry simplification and incomplete reflection of specific anatomical and biomechanical relations of the objects being modelled. The objective of this study was to develop and validate an accurate and universal numerical Finite Element Method (FEM) model of the human cervical spinal cord. Our survey focuses mainly on geometric, constraint and material aspects. Experimental validation was carried out based on a controlled compression of the porcine spinal cord specimens. Each stage of compression was simulated using the FEM model of the compressed segment. Our 3D numerical simulation results compared with experimental results show a good agreement. It is possible to use the developed numerical model of the human cervical spinal cord in the biomechanical analysis of the spinal cord injury phenomenon. However, further clinical evaluation is clearly justified.

14

Analysis of three-dimensional binary alloy solidification with shrinkage cavity formation

Skrzypczak T., Węgrzyn-Skrzypczak E.

Archives of Foundry Engineering

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2010

|

Vol. 10, iss. 4

199--204

EN

The paper focuses on modeling of binary alloy solidification process with using Finite Element Method (FEM). The process is characterized by liquidus and solidus temperatures which are constant because solutal segregation is neglected. Analysed region is threedimensional and consists of casting and riser. Mathematical and numerical models of solidification process are presented in the paper. The main focus is put on the algorithm of shrinkage cavity creation process. On the base of mathematical and numerical model computer program has been made. It is capable to simulate shrinkage cavity formation. Two examples show the results of different calculations performed by the program. The first example shows shrinkage cavity created during fast cooling of the top part of the riser while the second one was performed by significantly slower cooling. The shape and localization of shrinkage cavity obtained from simulation is compared to defect which was created during experiment.

15

Shape prediction during the free forming process of semi-finished products electrodynamically worked

Kot A., Bednarczyk J.

Mechanics / AGH University of Science and Technology

|

2007

|

Vol. 26, no. 1

8-15

EN

Possibility of free forming for semi-finished products and giving them demanded shapes without presence of forming dies distinguish the electrodynamic method in relation to standard technologies of metal plastic working, because there are no difficulties of using punch — die instrumentations. The article presents considerations referred to prediction possibilities of final shape of pipe and flat semi-finished products electrodynamically formed without using forming dies.

PL

Możliwość swobodnego formowania półwyrobów i nadawania im wymaganych kształtów bez udziału matryc wyróżnia metodę elektrodynamiczną (ED) w stosunku do klasycznych technologii plastycznej obróbki metali, gdyż nie stosuje się przy jej realizacji kłopotliwego oprzyrządowania typu stempel-matryca, a kształt półwyrobu po obróbce zależy od rozkładu sił Lorentza wywołanych polem magnetycznym wzbudzonym w obszarze induktor-półwyrób. W artykule przedstawiono rozważania dotyczące możliwości przewidywania końcowych kształtów półwyrobów rurowych oraz płaskich formowanych plastycznie metodą ED bez użycia matrycy.

16

FEM strength analysis of sandwich panels for ship structure applications

Augustyniak M., Porembski G.

Polish Maritime Research

|

2006

|

S 1

24-26

EN

This paper presents results of the numerical simulation modelling strength tests of laser-welded, foam-filled steel panels, performed by means of the Finite Element Method (FEM) within the frame of the ASPIS project. In this case application of the FEM makes it possible to significantly lower costs of determination of mechanical properties and optimization of the structure respective to its strength-weight ratio. The entire project as well as the presented calculations are aimed at implementing structures of the kind to shipbuilding industry. Results of the calculations modelling axial compression of panels comply with experiments qualitatively. The entire process of the structure’s compression till its collapse resulting from extensive plastic deformation within its middle zone, was step-by-step examined. Also, critical forces causing instability of the structure were determined. A partial quantitative discrepancy of the calculated reaction forces and those experimentally measured, requires further investigations.

17

FEM Modelling of the Plastic Flow Localization Induced in Metals by Surface Cracks

Marek P., Kurzydłowski K. J., Rożniatowski K.

Machine Dynamics Problems

|

2002

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Vol. 26, No. 4

69-81

EN

The aim of the present work is to provide a model for the influence of the surface films on the plasticity of metals. To this end Finite Element Method has been used to solve 2-dimensional plain strain problem. The effect of the film cracks on the deformation of the substrate for the specimens subjected to tensile straining has been studied using a number of models which different in the details of cracks geometry and origin as well as in the properties of both oxide film and metallic substrate. As far as the geometry is concerned, the following situations were analyzed: symmetric cracks on both sides of specimens - a) and a-symmetric crack on one side - b). For each of these two cases the crack depth has been varied in the range from 70 to 100% of the film thickness. As far as the cracks beginning is discussed the following two types of the cracks have been considered: * pre-existing cracks (existing in the film prior to the straining of the specimen), * fresh cracks (which develop during the straining). The model employed in the present study shows, that the macroscopic yielding of the specimens depends to some extent on the presence of the cracks in the surface film and is profoundly changed due to the presence of the residual stresses. The residual stresses due to the differences in the thermal expansion coefficients of the surface films and the substrates have been observed in the number of metals subjected to the annealing or surface treatment. The results reported here prove that these stresses deeply modify the flow stress of metals in the range of the micro-plasticity.