Wyniki wyszukiwania - BazTech

1

Organization of reverse engineering using modern calculation methods in the process of reproducing a gears

Pacana Andrzej, Pacana Jacek, Straka Martin, Woźny Artur

Zeszyty Naukowe. Organizacja i Zarządzanie / Politechnika Śląska

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2023

|

z. 170

371--382

EN

Purpose: The main purpose of this article is to present modern possibilities for the reproduction of a machine element. If there are no replacements for the damaged part, and there is no technical documentation, then the only options is to use reverse engineering (RE) methods to reproduce it. Design/methodology/approach: On the example of a damaged gear, the process of measuring the wheel and manufacturing a physical model using 3D printing. An additional step has been added to the classic reverse engineering process to modify the model to improve its strength. Findings: Strength analysis was carried out in the Abaqus program using the finite element method (FEM). Based on the results obtained, it was proposed to change the tooth profile of the gear, which will improve its durability. Research limitations/implications: An extension of the proposed scheme may be a modification of the production process in order to implement the reverse engineering method to the serial production of machine elements. Practical implications: The use of a modified reverse engineering (RE) process will not only allow the components to be reproduced but will also allow extended uptime of the components, and this will reduce production costs. Originality/value: The proposed new reverse engineering process can be successfully used to reconstruct machine components with even very complex shapes. The digital model obtained as a result of scanning has been used to improve the geometry of the toothed rim, but it can be successfully used for other analyses, research, or calculations.

2

Free vibration analysis of imperfect functionally graded sandwich plates: analytical and experimental investigation

Njim E.K., Bakhy S.H., Al-Waily M.

Archives of Materials Science and Engineering

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2021

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Vol. 111, nr 2

49--65

EN

Purpose: This paper develops a new analytical solution to conduct the free vibration analysis of porous functionally graded (FG) sandwich plates based on classical plate theory (CPT). The sandwich plate made of the FGM core consists of one porous metal that had not previously been taken into account in vibration analysis and two homogenous skins. Design/methodology/approach: The analytical formulations were generated based on the classical plate theory (CPT). According to the power law, the material properties of FG plates are expected to vary along the thickness direction of the constituents. Findings: The results show that the porosity parameter and the power gradient parameter significantly influence vibration characteristics. It is found that there is an acceptable error between the analytical and numerical solutions with a maximum discrepancy of 0.576 % at a slenderness ratio (a/h =100), while the maximum error percentage between the analytical and experimental results was found not exceeding 15%. Research limitations/implications: The accuracy of analytical solutions is verified by the adaptive finite elements method (FEM) with commercial ANSYS 2020 R2 software. Practical implications: Free vibration experiments on 3D-printed FGM plates bonded with two thin solid face sheets at the top and bottom surfaces were conducted. Originality/value: The novel sandwich plate consists of one porous polymer core and two homogenous skins which can be widely applied in various fields of aircraft structures, biomedical engineering, and defense technology. This paper presents an analytical and experimental study to investigate the free vibration problem of a functionally graded simply supported rectangular sandwich plate with porosities. The objective of the current work is to examine the effects of some key parameters, such as porous ratio, power-law index, and slenderness ratio, on the natural frequencies and damping characteristics.

3

Safety evaluation for a high signal operator with electric field exposure induced by contact wires

Yang Chang-Qiong, Lu Mai

Archives of Electrical Engineering

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2021

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Vol. 70, nr 2

431--444

EN

To evaluate the occupational safety of a high signal operator exposed to the electric field induced by contact wires with a frequency of 50 Hz and a voltage of 27.5 kV, this study established a model of a high signal operator working in the vicinity of single and double-track railways. The electric field distribution in the operator’s body and his head were calculated and analyzed during the operation using the finite element method (FEM). The calculated results were compared with the international standard occupational exposure limits formulated by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) and action levels (ALs), exposure limit values (ELVs) in Directive 2013/35/EU (EU Directive). In the case of a single-track railway exposure, the maximum electric field strength in the worker’s body, in the scalp layer, and inside the brain are 227 mV/m, 2.76 kV/m, and 0.14 mV/m, respectively. For a double-track railway exposure, the maximum internal electric field strength of the operator is 310 mV/m, which is 37.85% of the occupational exposure basic restriction limit. The maximum electric field strength in the head layers is 3.42 kV/m, which is 34.2% of the occupational exposure reference level and 34.2% of the low ALs. The maximum electric field strength of the brain is 0.19 mV/m, which is 0.19% of the occupational basic restriction limit and 0.135% of the sensory effects ELVs. Results show that the electric field exposure of the high signal operator to contact wires in single- and double-track railways is lower than the occupational exposure limits provided by the ICNIRP and EU Directive standards and is thus regarded as safe for workers.

4

LNG tank in Świnoujście: nonlinear analysis of the tank dome elements behaviour

Sobczyk Bartosz

Polish Maritime Research

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2020

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nr 4

139--147

EN

In this paper, the dome of a tank in the Świnoujście LNG terminal is analysed. Some of the rafter ribs at the connection with hangers were not mounted during construction of the tank dome. Therefore, it has become necessary to estimate its response, which has been done with the aid of some computational models of the dome, that have been created in the finite element method environment. Different local models are studied, aiming to recreate possible outermost conditions of the tank dome response, i.e. with or without composite action between steel and concrete parts of the tank dome. Static calculations with material and geometric nonlinearities are carried out on the computational models, enabling the creation of a load capacity envelope of the rafter with or without ribs. The obtained results are then used to decide if repair works need to be done and whether the missing ribs should be welded.

5

The impact of the structural form on the stress distribution in a flexspline of a hermetic harmonic driver

Pacana Jacek

Journal of Theoretical and Applied Mechanics

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2020

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Vol. 58 nr 4

1049--1060

EN

This paper presents a comparative analysis with different models of the flexspline for a harmonic hermetic drive. The flexspline is a thin-walled construction, deforming during work, so its design is a very complicated process. The paper contains a strength analysis for some selected models of this gear. Calculations were performed using the finite element method (FEM) in ADINA. The work presents stress diagrams in longitudinal intersections for susceptible wheels of different shapes for direct comparison. Suggested changes in construction of the flexspline will increase durability of a welded hermetic gear.

6

Composite beams with indented construction joint – comparison of results of laboratory tests and numerical analysis

Sadowski Grzegorz, Wiliński Piotr, Halicka Anna

Budownictwo i Architektura

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2020

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Vol. 19, no 4

31--42

EN

The paper presents a comparative analysis of the behaviour of a composite beam, consisted of a precast element with indented surface and new concrete layer, subjected to 4-point bending. The results obtained from the virtual model of the beam created using the finite element method (Abaqus/CEA 2019 software) were compared with the laboratory test results obtained with use of the digital image correlation (DIC) method for identifying the crack pattern. The virtual model of composite beam was calibrated by the choice of interface parameters ensuring that the value of load resulting in delamination between concrete layers was close to that value obtained in the laboratory tests. The comparative analysis showed that the pattern of bending and shear cracks and the pattern of interface crack obtained with the finite element method reflect the laboratory test results properly. It can be assumed that the crack between concrete layers is related to the appearance and propagation of shear cracks. On the basis of FEM analysis it can be concluded that the phenomena identified as “shear friction” and “dowel action” are significantly activated after the interface cracking.

PL

W pracy przedstawiono analizę porównawczą zachowania się belki zespolonej składającej się z prefabrykatu z powierzchnią ukształtowaną z wrębami oraz betonu uzupełniającego, poddanej czteropunktowemu zginaniu. Otrzymane wyniki z wirtualnego modelu belki zespolonej wykonanego za pomocą metody elementów skończonych (Abaqus/CEA 2019) porównano z wynikami badań laboratoryjnych, w których dla identyfikacji obrazu zarysowania użyto metody obrazowej (DIC – digital image correlation). Wirtualny model belki zespolonej został skalibrowany (przez zmianę parametrów styku pomiędzy betonami) w taki sposób, aby odspojenie pomiędzy betonami powstało przy tym samym obciążeniu, co w badaniach laboratoryjnych. Analiza porównawcza wykazała, że obraz zarysowania od zginania, ścinania oraz obraz rozwoju rys w styku uzyskany metodą elementów skończonych dobrze odzwierciedla rzeczywiste wyniki badań. Można przypuszczać, że zarysowanie pomiędzy betonami związane jest z pojawieniem się i propagacją zarysowania od ścinania. Na podstawie analizy MES można stwierdzić, że zjawiska identyfikowane jako „shear friction” oraz „dowel action” w znacznym stopniu uaktywniają swoje działanie po zarysowaniu styku.

7

Design Analysis of Closed Vessel for Power Cartridge Testing

Parate Bhupesh Ambadas, Chandel Sunil, Shekhar Himanshu

Problemy Mechatroniki : uzbrojenie, lotnictwo, inżynieria bezpieczeństwa

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2019

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Vol. 10, Nr 1 (35)

25--48

EN

This paper discusses the design analysis of closed vessel (CV) for power cartridge application in water-jet disruptor. In this article, various design theories are presented in which the vessel is subjected to internal pressure. CV is a kind of pressure vessel utilized to evaluate the performance of power cartridge used for water-jet application. It is a test vessel which generates pressure - time profile by burning the propellant. Energy derived from burning of the propellant of power cartridge aids in neutralizing Improvised Devices (IED's). This energy creates high water-jet plume in the disruptor. In order to evaluate various performance parameters of the cartridge, CV design plays a vital role in the research and development activities, including, development, life trials, production, lot proof trials and life extension / life revision trials. CV is one of the methodologies / techniques from which energy generated is measured in terms of the maximum pressure (Pmax) and the time to maximum pressure (TPmax). This paper also discusses about various design aspects using the finite element method (FEM) and their comparative results with different design theories. In the light of these theoretical, numerical, and experimental works, it was recommended that octahedral stress theory or van Mises theory should be used for vessel design. This satisfies the designer requirements. FEM analysis tool helps in reducing time & development cost.

8

Verification of FEM modelling of composite materials based on the results of static strength test

Gojny Katarzyna

Mechanik

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2019

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R. 92, nr 2

131--139

EN

The article presents the verification of FEM modelling of composite materials based on the results of static strength test. The aim of the work was to examine whether the applied modelling of composite materials is correct and verify it with finite element method (FEM). The composite structure of the PW-6U glider was used as a model. In the program the numerical model (geometry and finite element mesh) of the glider’s wing was created. The wing is made of glass fabrics and a spar with flanges with a glass roving. The composite structure of the wing, including composition, layout and thickness of laminate layers, fiber arrangement was exactly modelled in the program and then subjected to loads. Having the measurements from the static strength tests of the glider, the numerical results were compared with the experimental results. Thanks to the applied modelling, the obtained numerical results were satisfactory and very close to the experimental results from the structural static tests of the glider. Therefore, it can be concluded that the conducted verification of FEM modelling of composite materials is correct. Nowadays application of composite materials is increasingly expanding. Therefore, the modelling of composites becomes a significant issue. FEM modeling allows verification of the structure. At the stage of modelling modifications can be implemented and thus time and costs associated with subsequent changes in the production process may be saved. This is a very good solution which already at the design stage of the structure allows examination of its strength.

PL

Artykuł prezentuje weryfikację modelowania MES materiałów kompozytowych na podstawie wyników statycznej próby wytrzymałościowej. Celem pracy było zbadanie, czy zastosowane modelowanie kompozytów jest prawidłowe, i zweryfikowanie tego metodą elementów skończonych (MES). Jako modelu użyto konstrukcji kompozytowego szybowca PW-6U. W programie wykonano model obliczeniowy (geometrię oraz siatkę elementów skończonych) skrzydła szybowca. Skrzydło jest zbudowane ze szklanych tkanin oraz dźwigara z pasami z włókna szklanego. Kompozytową strukturę skrzydła, opisaną m.in. przez rozmieszczenie, układ i grubość warstw oraz ułożenie włókien, dokładnie zamodelowano w programie, a następnie poddano obciążeniom. Na podstawie pomiarów ze statycznych prób wytrzymałościowych szybowca porównano wyniki numeryczne z wynikami eksperymentalnymi. Dzięki zastosowanemu modelowaniu uzyskano zadowalające wyniki numeryczne, bardzo zbliżone do wyników eksperymentalnych z prób statycznych szybowca. Dlatego można stwierdzić, że przeprowadzona weryfikacja modelowania MES materiałów kompozytowych jest prawidłowa. W dzisiejszych czasach zastosowanie materiałów kompozytowych coraz bardziej się rozszerza. Dlatego modelowanie kompozytów staje się istotnym zagadnieniem. Modelowanie metodą elementów skończonych pozwala na weryfikację konstrukcji. Na etapie modelowania można dokonać jeszcze ewentualnych modyfikacji i tym samym zaoszczędzić czas oraz ograniczyć późniejsze koszty związane ze zmianami w procesie produkcji. Jest to bardzo dobre rozwiązanie, które już w fazie projektowania konstrukcji pozwala na zbadanie jej wytrzymałości.

9

Hybrid model of liquid metal flow and solidification

Hojny M.

Technical Transactions

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2017

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Vol. 7(114)

127--135

EN

The article presents a hybrid model dedicated to simulations of liquid metal flow and its solidification. The developed solution is a key component of the developed integrated modelling concept, which combines the advantages of physical and computer simulations, while the concept itself is the foundation of a scientific workshop oriented at high-temperature processes (close to solidus lines). Examples of test simulation results are presented, indicating that the adopted model assumptions are correct.

PL

W artykule przedstawiono hybrydowy model dedykowany symulacjom przepływu ciekłego metalu i krzepnięcia. Opracowane rozwiązanie jest kluczowym elementem rozwijanej koncpecji zintegrowanego modelowania łączącego zalety symulacji fizycznej i komputerowej, zaś sama koncepcja stanowi fundament warsztatu naukowego zorientowanego na procesy wysokotemperaturowe (bliskich linii solidus). Przedstawiono przykładowe wyniki symulacji testowych, wskazujących na poprawność przyjętych założeń modelowych.

10

Preliminary back-analysis of the height of mud brick fortifications based on geoarchaeological data at Tell el-Retaba site in Egypt

Trzciński J., Zaremba M., Rzepka S., Bogusz W., Godlewski T., Szczepański T.

Studia Quaternaria

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2017

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Vol. 34, Nr 2

99--108

EN

The Tell el-Retaba archaeological site is located at Wadi Tumilat, a shallow valley running from the Nile Delta to the Bitter Lakes. In ancient times, a route connecting Egypt with Syria-Palestine ran across the site. In the 13th century BC, during the rule of Ramesses II, a fortress surrounded by “Wall 1” was erected and in times of Ramesses III in the 12th century BC, a larger fortress surrounded by “Wall 2” and “Wall 3” was constructed. Using the finite element method (FEM) and ZSoil 2D&3D software, the wall heights were modelled and their soil-structure interaction was analysed. Strength of the wall depended on size and strength of bricks and mortar, brickwork, wall shape and foundation. Ancient builders using mud bricks must have known from practical experience the essentials of a wall construction, in which the height to width ratio was at 1.75 to 1.85. Moreover, they must have related the engineering properties of the material with the height of the construction and its purpose. The width to height ratio must have been used and related by ancient Egyptians to the ground resistance. Modelling has shown that, at wall width of 5 m, the foundation would have lost its stability at wall height of 13–14 m and bricks from the lower part of the wall would be destroyed. According to the undertaken assumptions, in order to retain stability, the wall height must have been limited to about 8–9 m.

11

An investigation of stresses and deformation states of clamped rotating functionally graded disks

Thawait A. K., Sondhi L., Sanyal S., Bhowmick S.

Journal of Theoretical and Applied Mechanics

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2017

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Vol. 55 nr 1

189--198

EN

The present study deals with the linear elastic analysis of variable thickness rotating disks made of functionally graded materials (FGMs) by the finite element method. The disks have radially varying material properties according to an exponential law, which is achieved by the element based grading of the material properties on the meshed domain. The results are reported for three types of thickness profiles, namely, uniform, linearly varying and concave thickness, having their mass constant. The disks are subjected to the clamped boundary condition at the inner surface and the free boundary condition at the outer surface. The obtained results show that in a variable thickness rotating disk, deformation and stresses are less as compared to the uniform thickness disk.

12

Analysis of fatigue crack growth in ship structural details

Leheta H. W., Elhewy A. M. H., Younes H. A.

Polish Maritime Research

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2016

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nr 2

71--82

EN

Fatigue failure avoidance is a goal that can be achieved only if the fatigue design is an integral part of the original design program. The purpose of fatigue design is to ensure that the structure has adequate fatigue life. Calculated fatigue life can form the basis for meaningful and efficient inspection programs during fabrication and throughout the life of the ship. The main objective of this paper is to develop an add-on program for the analysis of fatigue crack growth in ship structural details. The developed program will be an add-on script in a pre-existing package. A crack propagation in a tanker side connection is analyzed by using the developed program based on linear elastic fracture mechanics (LEFM) and finite element method (FEM). The basic idea of the developed application is that a finite element model of this side connection will be first analyzed by using ABAQUS and from the results of this analysis the location of the highest stresses will be revealed. At this location, an initial crack will be introduced to the finite element model and from the results of the new crack model the direction of the crack propagation and the values of the stress intensity factors, will be known. By using the calculated direction of propagation a new segment will be added to the crack and then the model is analyzed again. The last step will be repeated until the calculated stress intensity factors reach the critical value.

13

Thermo-Mechanical Deformation and Stress Analysis of Hydroxyapatite/Titanium FGM plate by FEM

Sharma R., Jadon V. K., Singh B.

Mechanics and Mechanical Engineering

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2016

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Vol. 20, nr 4

499--513

EN

Hydroxyapatite(HA)/titanium(Ti) functionally graded materials(FGM) are latest materials used for medical implants, structural components in defense, in dentistry, in aviation, and other fields under various type of loads. A finite element analysis model is designed to study the behavior of a HA/Ti FGM plate under thermo-mechanical loadings. Simply supported plate subjected to mechanical and thermal loads on its top and bottom surface is considered with suitable temperature and loading function. The first-order shear deformation plate (FSDT) method is used to investigate the thermo mechanical behavior of functionally graded plate .The volume fraction of the FGM plate is varied smoothly and continuously along the thickness of the plate. Results are discussed for the deformation and stresses of HA/Ti FGM plate It is observed from the study that FGMs are able to resist higher temperatures and loads without delamination.

14

Application of Image Processing to Predict Compressive Behavior of Aluminum Foam

Kim S., Chung H. J., Rhee K.

Archives of Metallurgy and Materials

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2016

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Vol. 61, iss. 2A

635--640

EN

An image processing technique was used to model the internal structure of aluminum foam in finite element analysis in order to predict the compressive behavior of the material. Finite element analysis and experimental tests were performed on aluminum foam with densities of 0.2, 0.25, and 0.3 g/cm3. It was found that although the compressive strength predicted from the finite element analysis was higher than that determined experimentally, the predicted compressive stress-strain curves exhibited a tendency similar to those determined from experiments for both densities. However, the behavior of the predicted compressive stress-strain curves was different from the experimental one as the applied strain increased. The difference between predicted and experimental stress-strain curves in a high strain range was due to contact between broken aluminum foam walls by the large deformation.

15

Dynamika struktury konstrukcyjnej śmigłowca w warunkach rezonansu naziemnego

Kowaleczko G., Gorecki T.

Zeszyty Naukowe / Wyższa Szkoła Oficerska Sił Powietrznych

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2015

|

Nr 4

103--109

PL

W artykule opisano wyniki badań symulacyjnych dotyczących drgań konstrukcji śmigłowca ILX – 27. Omówiono sposób utworzenia modelu obliczeniowego i przedstawiono najważniejsze wyniki obliczeń. Niektóre z nich były weryfikowane w oparciu o pomiary na rzeczywistym obiekcie.

EN

This paper describes the results of simulation research on structural vibration of the helicopter ILX - 27. It contains discussion how to create a computational model and presents the main results of the calculations. Some of them were verified on the basis of measurements on the actual object.

16

Zastosowanie metody makroelementów do rozwiązywania cienkich płyt ortotropowych

Delyavskyy M., Olejniczak M., Niespodziana A., Grabowski A., Janiak T.

TTS Technika Transportu Szynowego

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2015

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R. 22, nr 12

366--369, CD

PL

Opracowano nowe podejście do rozwiązania płytowych konstrukcji inżynierskich nazwane metodą makroelementów. Rozwiązanie konstrukcji sprowadza się do rozwiązania układu liniowych równań algebraicznych. Metoda daje lepszą dokładność rozwiązania w porównaniu z metodą elementów skończonych przy mniejszej liczbie równań. Rozwiązano dwa typy konstrukcji: płyta prostokątna swobodnie podparta oraz utwierdzona na obwodzie poddana działaniu obciążenia stałego.

EN

The new approach to solving of engineering constructions called as macroelement method has been worked. The solution of construction is reduced to solv-ing of system of algebraic equations. The method gives a better accuracy in comparing of finite element method for less number of equations. There are considered two types of constructions: rectangular plate free supported or clamped at the counter and loaded uniformly.

17

Soft glass spiral photonic crystal fiber for large nonlinearity and high birefringence

Revathi S, Inabathini S, Sandeep R

Optica Applicata

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2015

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Vol. 45, nr 1

15--24

EN

This paper presents a soft glass spiral photonic crystal fiber with circular air holes for achieving high birefringence, large nonlinearity and large negative dispersion. The material used here for designing the fiber is soft glass (SF-57). A central defect air hole is being introduced in the core for achieving high birefringence and for different ellipticity ratios the effect of various optical properties of a photonic crystal fiber are studied. The structure proposed has a high birefringence in the order of 10–2, high nonlinearity of 5828 W–1km–1 and high negative dispersion of –1546.6 ps/nm•km at 0.850 μm. A numerical approach based on the finite element method is used for the design and simulation of the structure. Due to the optimization in the cladding air holes, the fiber can be used as polarization maintaining fibers, in dispersion compensation and other nonlinear applications.

18

FEM model of induction hardening of gear of mixture material

Hodek J., Shykula P.

Journal of Achievements in Materials and Manufacturing Engineering

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2015

|

Vol. 71, nr 2

87--92

EN

Purpose: The purpose of this article is to describe the construction of an FEM model for computing residual stresses generated by induction hardening of a high-carbon steel gear. Design/methodology/approach: The 3D FEM model comprised two parts. The first one which dealt with induction heating was prepared using MSC Marc commercial software. The second one, a model of temperature and deformation fields, was developed with the aid of DEFORM 3D commercial software. Material data was considered to be temperature-dependent. In the second part of the model, the material data was defined on the mixture basis: a separate temperature-dependent data set was specified for each phase, including transformation rules. The data was obtained in part by measuring and in part by calculation using JMatPro commercial software. Temperatures during heating and cooling were measured by means of thermocouples. The convection heat transfer coefficient was determined and the model of induction heating validated using the measured data. The thickness of the martensitic layer upon heat treatment was measured to validate the model. Findings: The 3D FEM model described here predicts the temperature distribution during heat treatment and the thickness of the martensitic layear upon heat treatment accurately. It was thus deduced that this material model was defined correctly and that the calculation of residual stresses would correspond to the reality. Practical implications: Future work should focus on refining the model, e.g. on incorporating transformation plasticity and on analysing the relationship between the residual stress distribution upon heat treatment and the part’s fatigue. Originality/value: The material model described in this article takes into account phase transformations which have a substantial impact on the post-treatment distribution of residual stresses. The 3D FEM model with this type of definition of material provides good predictions of residual stress distribution in the gear.

19

Numerical And Experimental Analysis Of Fracture Of Athrombogenic Coatings Deposited On Ventricular Assist Device In Micro-Shear Test

Kopernik M., Milenin A., Kąc S.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 2A

795--800

EN

The Polish left ventricular assist device (LVAD – RELIGA_EXT) will be made of thermoplastic polycarbonate-urethane (Bionate II) with deposited athrombogenic nano-coatings: gold (Au) and titanium nitride (TiN). Referring to the physical model, the two-scale model of LVAD developed in the previous works in the authors’ finite element code is composed of a macro-model of blood chamber and a micro-model of wall: TiN, Au and Bionate II. The numerical analysis of stress and strain states confirmed the possibility of fracture based on localization of zones of the biggest values of triaxiality factor. The introduction of Au interlayer between TiN and polymer improved the toughness of the connection, and increased the compressive residual stress in the coating what resulted in reduction of stress and strain close to the boundary between substrate and coating. However, the proper design of multilayer wall of the medical device requires the introduction of the real stress and strain states in the deposited coatings. The characteristics of TiN nano-coating such as residual stress, material model and fracture model were determined in the previously completed studies such as experimental and numercial nanoindentation tests, profilometry studies and in situ SEM’s micro-tension tests. The experimental in situ SEM’s micro-shear test was performed in the present paper and the corresponding numerical model of the test was also developed, and then, interpreted. The critical strains taken from experiment and considered as the effective strains in the model of test are the values which are the function of triaxiality factors for the tested samples. The developed in the authors’ FE code model of multilayer wall of VAD enriched with critical strain determined in the present paper enables prediction of fracture.

PL

Polska lewa komora wspomagania pracy serca (LVAD – RELIGA_EXT) zostanie wykonana z termoplastycznego poliwęglano-uretanu (Bionate II) z naniesionymi atrombogennymi powłokami: złota (Au) i azotku tytanu (TiN). W odniesieniu do modelu fizycznego, dwuskalowy model komory LVAD opracowany we wcześniejszych pracach w autorskim kodzie elementów skończonch jest złożony z modelu makro czaszy krwistej i z mikro-modelu ściany: TiN, Au i Bionate II. Analiza numeryczna stanów naprężenia i odkształcenia potwierdziła prawdopodobieństwo pękania poprzez zlokalizowanie stref o największej wartości współczynnika naprężenia trójosiowego. Wprowadzenie międzywarstwy złota pomiędzy TiN i polimer poprawiło wytrzymałość tego połączenia i powiększyło ściskające naprężenie własne w powłoce, co doprowadziło do redukcji naprężenia i odkształcenia blisko granicy pomiędzy podłożem i powłoką. Jednakże, właściwy projekt wielowarstwowej ściany urządzenia medycznego wymaga wprowadzenia rzeczywistych stanów naprężeń i odkształceń w naniesionych powłokach. Charakterystyki powłok TiN takie jak naprężenie własne, model materiału i model pękania zostały określone we wcześniej wykonanych badaniach takich jak doświadczalne i numeryczne testy nanoindentacji, badania profilometryczne, i testy mikrorozciągania prowadzone pod elektronowym mikroskopem skaningowym. W niniejszej pracy przeprowadzono doświadczalny test mikrościnania pod skaningowym mikroskopem elektronowym, opracowano model numeryczny tego testu, a następnie go zinterpretowano. Odkształcenia krytyczne otrzymane z doświadczenia i określone w modelu testu jako intensywność odkształcenia są wartościami będącymi funkcją współczynników naprężeń trójosiowych dla badanych próbek. Opracowany w kodzie własnym model elementów skończonych wielowarstwowej ściany komory VAD wzbogacony o określone w niniejszej pracy odkształcenia krytyczne umożliwia przewidywanie pękania.

20

Failure Strain and Strain-Stress Analysis in Titanium Nitride Coatings Deposited on Religa Heart Ext Ventricular Assist Device

Kopernik M.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 1

121--129

EN

The Polish ventricular assist device is made of Bionate II with deposited TiN biocompatible nano-coating. The two scale finite element model is composed of a macro-model of blood chamber and a micro-model of the TiN/Bionate II. The numerical analysis of stress and strain states confirmed the possibility of fracture. Therefore, the identification of a fracture parameter considered as a failure strain is the purpose of the present work. The tensile test in a micro chamber of the SEM was performed to calibrate the fracture parameter of the material system TiN/Bionate II. The failure strain is a function of a temperature, a thickness of coating and parameters of surface's profile. The failure strain was calculated at the stage of the test, in which the initiation of fracture occurred. The finite element micro-model includes the surface roughness and the failure strain under tension condition for two thicknesses of coatings which will be deposited on the medical device.

PL

Polska komora wspomagania pracy serca jest wykonana z Bionate II z naniesioną biokompatybilną powłoką TiN. Dwu-skalowy model elementów skończonych składa się z modelu makro czaszy krwistej i z modelu mikro dla TiN/Bionate II. Numeryczna analiza stanów naprężeń i odkształceń potwierdza prawdopodobieństwo pękania. Zatem, identyfikacja parametru pękania rozpatrywanego jako odkształcenie uszkodzenia jest celem niniejszej pracy. Próba rozciągania w komorze SEM została przeprowadzona, aby skalibrować parametr pękania dla układu materiałowego TiN/Bionate II. Odkształcenie uszkodzenia jest funkcją temperatury, grubości powłoki i parametrów profilu powierzchni. Odkształcenie uszkodzenia zostało obliczone w tym etapie testu, w którym pojawiła się inicjacja pęknięcia. Mikro model elementów skończonych zawiera chropowatość powierzchni i odkształcenie uszkodzenia w warunkach rozciągania dla dwóch grubości powłok, które będą nanoszone w tym urządzeniu medycznym.