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M. Cetkovic, DJ. Vuksanovic
FREE VIBRATIONS OF LAMINATED COMPOSITE PLATES USING LAYERWISE DISPLACEMENT MODEL

In this paper Generalized Layer Wise Plate Theory of Reddy (GLPT) is used to formulate an isoparametric finite element model for free vibration of laminated composite plates. With the assumed displacement field, linear strain displacement relations and linear elastic orthotropic material properties for each lamina, virtual work statement is utilized in order to formulate isoparametric finite element model. The original MATLAB computer program is coded for finite element solution. Some new results using GLPT finite element model for soft core sandwich plate is presented, which may be used as the guideline for their optimal design in the laboratory.

M. Kostelecká, J. Kolísko, D. Kytyr
THE MONITORING OF THE CEMENT PLATE’S SHRINKAGE

You can hardly find an industry, in which you would not use textile fibres. From the mid-1940s, fibres or textiles found a wide range of use in material engineering in development of new material types, such as reinforcement of textile - building composite. They are used because of their relatively high strength and high mechanical elastic fibre modules. This serves for creation of composite materials (continuous matrix and reinforcement fibres or textile).

G. L. Pintilei, D. S. Dragomir, L. A. Dragan, I. V. Crasmaru, A. C. Barbinta, C. Munteanu
MULTIDISCIPLINARY ANALYSIS OF THE OPERATIONAL TEMPERATURE INCREASE OF TURBINE BLADES FOR AIRCRAFT ENGINE BY APPLICATION OF THE CERAMIC THERMAL BARRIER COATINGS ZrO2/20%Y2O3<

The improvement of the temperature resistance of the aircraft engine elements can be obtained by application of a ceramic coating, single layer (TBC) or several composite layers. Turbine blades are made of a super alloy that has a maximum operating temperature of close to 1000°C, the idea of using ceramic materials was foreseen. To increase thermal resistance of engine the elements requires, apart from laboratory investigations, also numerical study of the different aero-engine parts. For aircraft engine the most important are turbine blades, where high temperatures and stress concentrations during thermal shocks or thermal fatigue can be observed during engine exploitation.
The present paper deals with the solution of the transient temperature transfer problem in bare and thermal barrier coated alloy Inconel 625 for the temperature range up to 1000 ºC. The computational fluid dynamics (CFD) part of analysis was performed by application of ANSYS Fluent code receiving the temperature field of combustion gas.

G. L. Pintilei, G. N. Basescu, S. A. Iacoban, A. C. Barbanta, C. Munteanu
COMPARATIVE RESEARCH ON THE STRUCTURE AND PROPERTIES OF ZrO2/20% Y2O3 LAYERS OBTAINED WITH PLASMA SPRAY DEPOSITION METHOD

Ceramics and ceramic materials are materials with promising technical applications and with relatively high characteristics in terms of mechanical strength, but at the same time very low properties due to the fragility and the cracks appearing in the cooling layer. The cracking resistance is important not only for the technical products which operates in the mechanical thermal loads domain but also for structural components, cracks of which fragility is unacceptable even in arbitrary tasks.In this paper its being revealed a new concept of TBC with an exfoliation prevention of the sprayed layer and it consists in an adherent layer of NiMoAl (90-5-5) sprayed through an electric arc and a top coat of ZrO2/20%Y2O3, deposited by atmospheric plasma spraying (APS) on specimens of Ni base superalloy, of which the aircraft turbine blades are made. There were made some attempts of spraying at different distances, namely: 100 mm respectively 110 mm. These samples had been then subjected to mechanical bending tests to observe adhesion to the substrate. Highlighting and interpretation of structural changes caused by the tests carried out have been made using modern methods of structural analysis

C. Munteanu, G. L. Pintilei, C. Paulin, C. I. Barbînta
STRUCTURAL STUDIES OF THE PLASMASPRAYED LAYERS DEPOSITED ON THE STEAM TURBINE BLADES

The method of plasma spraying for obtaining superficial layers with special properties has begun to be increasingly used in industry. In this paper are described and presented a series of layers experimentally obtained, using powders of WC-Co type on different substrates (steel and Ni alloy) in order to observe the influence of the substrate on the interface and the characteristics of the deposited layer. The attention was paid to the layers that must meet the hardening requirements of the steam inlet borders in the rotor blades network of the low-pressure body of the steam turbines. The analyzed samples were obtained by thermal spraying, using an atmospheric plasma spray installation type SPRAYWIZARD - 9MCE. To highlight the results were performed analyses of scanning electron microscopy (electron microscope type QUANTA 200 3D DUAL BEAM) and X-Ray diffraction (diffractometer X’PERT PRO MRD) for determining the phases and constituents from the deposited layer.

G. N. Basescu, P. Avram, V. C. Stamate, L. A. Dragan, C. I. Barbanta, C. Munteanu
WEAR RESISTANCE OF THE LAYER Al2O3-TiO2 SPRAYED WITH PLASMA SPRAY DEPOSITION METHOD

The incorrect operation of the camshaft affects not only the normal engine service, but also its economic indices. The gas distribution mechanism elements are especially submitted to mechanical wear. Therefore, the main aspects of this type of wear can be found, grouped as followed: contact wear, abrasive wear, fatigue wear, particularly its pitting, exfoliation, cracking. The deposited layer comes as a filler element to the basic material and between these two can speak of a limit of separation or interface more or less clearly delineated. This paper presents a new concept of thermal barrier coating for the prevention of delaminating of the sprayed layer. This consists in an adherent layer of Ni Mo Al (90-5-5) and a top coat of Al2O3-TiO2, deposited by atmospheric plasma spraying (APS) on specimens of nodular cast iron of which the camshaft are made. Using the CETR UMT-2 tribometer there were made friction and wear tests. Highlighting and interpretation of the structural changes caused by the tests carried out have been made using modern methods of structural analysis.

G. N. Basescu, G. L. Pintilei, G. B. Pamparau, A. C. Barbînta, C. Munteanu
INNOVATIVE CHARACTER OF PLASMA SPRAY DEPOSITION METHOD, AT THE CERAMICS POWDER Al2O3-TiO2

The Atmospheric plasma spraying method (APS) is one of most used methods for deposition on layers with different thickness on surfaces with different degrees of complexity.
This paper presents a new concept of thermal barrier coating for the prevention of delaminating of the sprayed layer and this consists of an adherent layer of Ni Mo Al (90-5-5) and a top coat of Al2O3-TiO2, deposited by atmospheric plasma spraying (APS) on specimens of nodular cast iron of which the camshaft are made of the internal combustion engine.
The samples studied in this paper were obtained by thermal spray using an atmospheric plasma spray installation SPRAYWIZARD - 9MCE.
To highlight results, SEM (Scanning Electron Microscopy) analyses were performed using a Quanta 200 3D Microscope Dual Beam. Using x-ray analysis it was possible to detect the existing phases and constituents in the layer deposited with the plasma spray method and comparisons were made about the composition of the used powders. Testing adhesion and cohesion of the coating by the "scratch" was made with micro tribometer UMTR 2MCTR.

C. Axinte, A. Bârca, E. S. Bârca, B. Istrate, C. I. Barbînta, C. Munteanu
COATINGS PROPERTIES OBTAINED BY THERMAL DEPOSITION USED IN GEARS APPLICATIONS

Gears tooth are subjected to fatigue and bending. In operating, on the tooth flanks gears appears a wear type pitting. The geometry, can’t be modificated that is why we decided to modify the contact surface by thermal deposition of an addition material. We made a detailed study of the literature and we decided to use an usual steel which we coated with powder by electro spark process. We have chosen the OLC 45 steel and we coated it with WC. After we obtained the samples, we subjected them to bending tests in order to determine the bending stress and the elasticity modulus. On SEM analysis we obtained the image and the quality of the coatings. The results showed how the coating increases the properties of the basic material.

C. Axinte, A. Bârca, E. S. Bârca, P. Avram, C. I. Barbînta, C. Munteanu
DETERMINATION OF MO COATINGS BEHAVIOUR ON BENDING IN ORDER TO ESTABLISH SOME MECHANICAL PROPERTIES

Gears have the role of force and torque transmition by friction. They are subjected in operating to fatigue and bending, this being the reason of the pitting type wear appearance. The geometry, dimensions and weight can’t be modificated that is why we decided to modify the contact surface by coating. We have chosen the steel type 16MnCr5 and we coated it with Mo. The selection of the materials was made after a detailed study of the literature. After we obtained the samples, we subjected them to bending tests to determine the mechanical properties. On the SEM analysis we obtained the quality of the coatings. The results showed how the coating influences the properties of the basic material.

P. Zlamal, D. Kytyr, T. Fila, P. Koudelka, O. Jirousek
MEASURING OF ELASTIC PROPERTIES OF METAL FOAM BASED ON COMPRESSION TEST AND DIGITAL IMAGE CORRELATION

From a mechanical point of view the most important ability of metal foam is absorption of large amounts of strain energy. This advantage is based on the cellular structure with high ratio of porosity (75-95%). The aim of this study is determination of stress-strain measurement protocol for closed-cell aluminium metal foam Alporas® during a compression test using in-house loading device. Changes in structure were observed and strain was calculated based on Digital Image Correlation (DIC) technique. For the assessment of overall compression elastic modulus a new software tool based on the Matlab toolkit was developed.

Page 641 of 977 Results 6401 - 6410 of 9762