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The fiber reinforced plastic (CFRP) are widely used in stacks with metallic materials. The parts are usually bolted together during assembling procedure. That is why drilling is one of the most widely used operations for machining of CFRP/metal and metal/CFRP stacks. That allows to obtain components, which combine high strength and low weight. This paper presents tool wear study based on the drilling experiment of CFRP/ steel stack. The most common problems of CFRP/metal stacks machining are CFRP delamination, fiber pull - out, thermal degradation and intensive tool wear. Last decade such parameters of CFRP/metal stacks drilling as axial force and torque are in the focus of researches. However, the cutting temperature in the drilling process of CFRP/metal stack and its influence on drill bit wear is still not fully gained at the present time. The purpose of current study is to investigate the effect of cutting temperature on the tool life of carbide drill. The temperature was measured with K type thermocouple which was embedded on the flank surface of the drill. Axial force was measured with dynamometer. Data of cutting temperature and axial force was digitalized with analog - digital converter (ACD) and visualized on personal computer (PC). The dominating tool wear mode when drilling CFRP/steel - was flank wear which was measured with optical microscope. The experimental study of cutting temperature effect on the tool wear of carbide drill was established. It was found that the most unfavourable combination of stack materials in the conditions of drill wear is CFRP/metal.

Authors define general dependability characteristics (reliability, maintainability, supportability and availability) and their measures. Further there is introduced method of data collection which shall be planned taking into account appropriate targets. Dependability data analysis needs clear understanding of an object, its operation, environment and physical attributes to be obtained required dependability measures which are described. These measures can be used as indicators for measuring maintenance impacts on reliability and maintainability. Data collection and its evaluation help to monitor the impact of maintenance on these indicators. Dependency between non-fulfillment of preventive maintenance and failure intensity including maintenance costs are also evaluated.

An adhesive bonding technology is a method of a connecting which is used at a construction of coach-works, agricultural machines etc. This method is suitable for workings with a serial production. Many research projects dealt with a preparation of adhesive bonds, degradation aspects etc. An area, which has not been properly investigated at present, is an influence of a loading speed on strength of the adhesive bond and a destruction time of the adhesive bond. Adhesive bonds are loaded by a different intensity and a speed at a practice.
The research focused on an evaluation of the influence of the loading speed at a temperature 22 ± 2 °C on the shear tensile strength, the time needed for the destruction and a failure area. Second part of the research was focused on the influence of a bending moment. This bending moment can be minimalized by using so-called underlaying sheet of metal. The underlaying sheet of metal was of a thickness corresponding to a thickness of the adhesive bonded material. Also a behaviour of the adhesive bonded material was observed within the research.

This article describes the effect of selected parameters of plasma nitriding on the change of dynamic parameters of steel DIN 1654/4. Plasma nitriding is currently used in a wide range of technical applications such as a final operation to improve the mechanical properties of components. This experimental investigation is devoted to the analysis of the influence of plasma nitriding on the notch toughness of structural steel DIN 1654/4 (CSN 41 2042.4). The test of the dynamic fracture behaviour of structural steel was carried out using by instrumental Charpy hammer on the plasma nitrided specimens with V and U notch, manufactured according to standard CSN ISO 148-1. The plasma nitriding was implemented at 500 (°C), process duration t = 10 and 20 (h) and variable gas mixture ratio of 24H2: 8N2 (l/h) and 8H2: 24N2 (l/h). The test results showed that nitrided steel has become more brittle. However, it was found that for different gas composition, the notch toughness has behaved quite diversely. The values of notch toughness of steel in case of gas ratio 8H2: 24N2 (l/h) were decreased but for gas ratio 24H2: 8N2 (l/h), with extension of time, the notch toughness was slightly increased.

Approximately equiatomic alloy Ni-Ti is commercially most successful member of shape memory material group. This paper concludes basic knowledge about properties, ways of preparation and possible applications of this unique material in medicine, industry, construction or everyday life.

The use of renewable energy sources in Slovakia is currently very debated issue. The main cause of this discussion is the increase of energy prices, which increasingly burden the population and companies. The use of renewable sources, including biomass, represents an important contribution to solve this problem. When new heat source is designed, several technical regulations and recommendations must be followed. The proposed device is intended to serve for combustion of biomass, in the form of wood, of pellets. The aim of this work is to describe the design process of the combustion device as the main source of thermal energy in our proposed micro-cogeneration unit.

This paper is aimed at chemical-heat treatment of a selected material. The plasma nitriding layers were applied on the 41CrAlMo7-10 steel. The influence of plasma nitriding parameters on the thickness and microhardness of nitrided layers were investigated. Plasma nitriding was performed at 500°C with a mixture atmosphere of H2 and N2 in the plasma nitriding equipment. The pressure of plasma nitriding process was determined to be 280 Pa. The period of the plasma nitriding process was changeable from 5 to 30 hours. The microstructure and mechanical properties of the nitrided layers were studied by using GDOES spectrometry, optical microscopy, and hardness testing. The depths of the plasma nitriding layers were also estimated using cross-sectional microhardness profiles. Microhardness and surface hardness of mentioned samples were significantly increased. The measurements have shown that the period of plasma nitriding process has a significant influence on the depth of nitriding.

For the creation of the bond the treatment of the adhesive bonded surface is essential. The second important factor is the temperature of the environment to which the adhesive bond is exposed. It is a way of a degradation of adhesive bonds. The aim of the research was to evaluate the effect of adhesive bonded surface treatment of alloy AlCu4Mg and increased environmental temperature on a strength of adhesive bonds using two-component epoxies used in the transportation industry. As a bonding material AlCu4Mg was used, whose surface was in the first series mechanically and chemically treated. In the second series tested specimens were without the surface treatment. A destructive testing was conducted at a laboratory temperature 22 ± 2 °C and at increased temperatures, i.e. 40, 60 and 80 ± 2 °C. At a mutual comparison of the mechanical treatment and the chemical treatment of the adhesive bonded surface with un-treated surface, the tensile lap-shear strength increased by an average of 57.24 ± 18.52 %. The results show that there is a difference in the tensile lap-shear strength between the test temperatures in the interval 20-80 °C, the decrease was up to 88 %.

The aim of this research work was to determine the causes of the cracking unit rolled at initial hot rolling of the AlMg5 alloy. Failure occurs in the central area of rolled plate. In the alloy was carried out chemical composition of the material in the near the defect and its comparison with the chemical composition of the entire melt, which pointed to a significant reduction of the magnesium content of the area defect. Macroscopic, microscopic and fractography analysis were carried out both in the area of the fracture surface and in the immediate vicinity. The analysis indicated that the fracture surface, and also the structure in the area of the fracture surface show a character oxide inclusions and oxide films or spinel inclusions. The following EDS analysis were carried out on a scanning electron microscope to confirm the presence of oxide inclusions of spinel-type character Al2MgO4 on the fracture surface of the rolled material. It could be stated that when casting a gradual burning out of magnesium in casting furnace and thus to reducing it's some 0.5 - 1.0% and the formation of spinel inclusions. Spinel inclusions then initiated cracking during hot rolling.

Self-hardening aluminium alloy AlZn10Si8Mg represents an innovative class of light aluminium alloys and they present high mechanical properties, which make them suitable for many applications in different industrial fields, especially in transport industry. The most important and relevant feature of the self-hardening alloys is related to their good performance, without the need of any heat treatment: they are subjected to a natural ageing phenomenon at room temperature after a storage period of about 7-10 days. The possibility to avoid the heat treatment represents an important benefit, contributing to considerably reduce both the production cost of some components and the amount of energy. Furthermore, without heat treatment the risk of component's deformation during the production is eliminated.
The Charpy impact energy of experimental cast alloy was measured at -196°C, -20°C, 20°C, 50°C, 100°C, 150°C, 200°C, 250°C, 300°C, 350°C and 400°C in terms of the total absorbed energy. Effect of temperature to microstructural changes and fracture surface on the impact toughness was investigated. A combination different analytical techniques (light microscopy upon black-white etching, scanning electron microscopy (SEM) upon deep etching) were therefore been used for the identification of the various phases.

Dynamic characteristics of a machine-tool-workpiece system are not constant during machining, but they can be changed by a variable spindle position, a rising tool wear or a gradual change of a workpiece geometry. This paper deals with an influence of spindle unit extrusion on stability of a machining process. Two milling cutters with different rigidity, flexible and stiff, were used for experimental machining at three axis milling machines. Clamped milling cutters were extracted systematically and a frequency response function was measured simultaneously. Reached data (natural frequency and dynamic compliance) were used for finding a correlation between dynamic parameters and extrusion of the spindle. Critical extrusion of the spindle unit was predicted by an experimental measurement and an axial depth of cut thresholds was established for the stable machining.

The aim of this paper is to describe anodizing technology for deposition of Al2O3 coatings on Al substrates. Various methods of layer deposition were used for the experiments. Deposition was carried out in acidic environments, using sulphuric acid (H2SO4) and chromic acid (H2CrO4). Several samples were heat treated (annealed). Chemical composition of the substrate and the coating was tested by GDOS method using SA2000 and GDS 500A devices. Surface morphology and structure were evaluated by SEM, using VEGA5135 electron microscope. Selected mechanical properties as thickness, microhardness and adhesion were also determined.

This article deals with the influence of the alloy temper during heat treatment on mechanical and corrosion properties of aluminium alloys 2024 (Al-Cu-Mg) and 6064 (Al-Mg-Si). For the experiment initial alloy tempers 2024-T351 and 6064-T8 were heat treated to three conditions - underaged, peak aged (T6) and overaged - to simulate the circumstances during the manufacturing process. Structure of all conditions and tempers was observed. The mechanical properties - hardness, yield strength, ultimate strength and elongation - and corrosion properties - maximum depth of corrosion attack peneration and corrosion rate in Audi immersion test for automotive industry (internal standard PV 11 13) - were measured. Structures of investigated alloy show evidence of intermediate phases arrangement in the direction of plastic deformation and they do not change during heat treatment. The lowest hardness, yield strength and ultimate strength have the underaged samples, the highest hardness, yield strength and ultimate strength have peak aged (2024) or initial samples (6064). Elongation decreases with ageing time or ageing temperature. In case of alloy 2024 corrosion rate and maximum depth of corrosion attack penetration increase with ageing time or temperature, in case of alloy 6064 corrosion rate increases with increasing ageing time or temperature while maximum depth of corrosion attack penetration decreases. Both alloys are attacked by intergranular corrosion with initiating surface pits.

Fiber reinforced polymer Resin matrix composites have the good performance, and it is widely used in various fields to release the impact load. Therefore, the study of stress and strain characteristics is quite useful to in providing the reliable basis for the structural design. The tensile test is one of the important methods to detect the mechanic property of the material, which can be used to observe the deformation behavior of the material. Reinforced materials are often added to improve the mechanical properties of the composites, and characteristics and mechanical properties of composite materials will be obvious anisotropic. Damage behavior of resin matrix composite material with fiber reinforced is complex, and mechanical properties of it are quite difficult to obtain just through the experiments, so the finite element method becomes a useful tool to get the mechanical properties. In this paper, we developed the conventional finite element method to investigate the mechanical properties of composites material. The verification proves that the modified finite element method can get much accurate results.

The analysis of non-metallic initiating inclusions in fatigue live field is studied. The testing material for experiments is CSN 41 5340 steel (corresponds to 41CrAlMo7-10 or 1.8509). This steel is suitable for plasma nitriding process. The samples were heat treated and subsequently plasma nitrided, then subjected to the fatigue bending rotation tests. According to the principle of the tests are the conditions set to constant speed and decreasd load to 107 cycles if does not the fatigue fracture of the sample happens. The thickness of the diffusional nitride layer has been won using the microhardness measuring from the surface to the core of the samples. Using the fractographic analysis the nucleation point of fatigue crack has been evaluated. In the case of initiating inclusions the size and the chemical composition was measured. Comparing the won data to the plasma nitriding proces new results have been obtained.

Hydroxiapatite is ceramic material with properties and composition similar to the bone tissue. This makes it a suitable choice for biomaterials. However, hydroxyapatite alone has poor mechanical properties. Present paper shows two possible applications of hydroxyapatite in materials intended for medical applications. 1. Hydroxyapatite can be used as a layer which causes the material to be more bioactive. In this article the layer of HA is applied on WE43 by plasma spraying and structure, composition and adhesive properties are measured. 2. Hydroxyapatite can serve as reinforcement in metallic composite materials. Present work sum up properties of composite materials with 2, 5 and 10 wt.% of HA that were prepared by powder metallurgy route. The structure, hardness and compressive mechanical properties are characterized.

Paper deals with comparasion of methods for resolving stress state on the example of forged crane hook of selected load. For suitability of the comparasion is necessary to achieve comparable stress values by different methods. Problem of solving of different assignments by different methods is very extensive, and because of it, there is not clear answer, which of methods is universal and so always optimal. Any factors, that enter to the calculation and influence it, is the best way to choose an optimal method for solving of strength problems in mechanics.

The article presents numerical code which was developed for solution of inviscid compressible fluid flow in domains with deforming boundaries. This computational method for the numerical solution of the non-linear system of Euler equations in time-dependent domains was designed as the first step of solution of fluid-structure interaction problem. Arbitrary Lagrangian - Eulerian (ALE) description of continuum, combining Eulerian and Lagrangian approach, was used to describe the inviscid fluid flow in time-dependent domain. The spatial discretization was provided by finite volume method adapted for triangular computational grids. Inviscid fluxes were discretized by the Rusanov flux scheme and Van Leer flux splitting scheme. The computational code was validated using a case of inviscid fluid flow around vibrating airfoil NACA 0012 which was experimentally investigated by AGARD group in 1982. Boundary conditions and simulation parameters were set according to the conditions of experimental measurement and the rotation angle of the body was defined by a time-dependent function. The numerical results are compared with experimental data and results of other authors. The algorithm for the mesh deformation is presented.

The paper analyses the possibilities of modification of cutting tool geometry in order to preserve a protective plastic zone of material at a cutting tool. Based on the results of model experiment as well as practical verification, a rapid increase in tool life has been achieved. The tool life is dependent on the size of the shortened rake face. Optimization of the tool face size enables to achieve multiplied tool life when comparing with a classical cutting tool. A uniqueness of this processes is the formation of the two chips, one of which is a created plastic layer along the edge of the cutting tool. The application of the tool is possible only with the plastic material cutting. Experimental tests were realized with usually used steels.

The Al-brasses are considered corrosion resistant technical materials especially used in pipe systems in energy industry. They are mostly exposed to flowing liquids environments where they are loading chemically and mechanically and their lifetime in practice condition quite vary. The aim of our research work is to compare corrosion and mechanical properties of four Al-brasses from various producers. The Al-brasses have very similar chemical composition but differ in microstructure, surface state what affect their corrosion and mechanical behavior. By chosen experimental methods and analyses the effect of the mentioned parameters are investigated.

This paper deals with the influence of alloying elements on the properties of Ni-Ti alloys. The base alloy was the binary alloy Ni-Ti with 54 wt. % Ni and 46 wt. % Ti. Alloying elements (aluminium, iron and vanadium) in an amount of 5 wt. % were added to this alloy. All samples have been prepared by the method of powder metallurgy - reactive sintering at 1100 °C for 20 minutes. Microstructure, phase composition (especially amount of the Ti2Ni phase), process of sintering and the formation temperature of intermetallic phase NiTi, transformation temperatures and mechanical properties have been examined in these alloys. The corrosion characteristics were measured on the Ni-Ti and NiTiV5 alloys.

Usually, the coatings used in industrial applications require post-processing to reach their final shape. However, some of these coatings are difficult-to-cut, mainly because of their high hardness. The present study provides a revision of some experimental investigations on the turning of WC-Co, Stellite, and Fe-based and NiAl alloys. The materials are used for both coatings and sintered workpieces providing insights for conducting turning tests. For the success of the turning process, the selection of the machining parameters is a critical issue. Based on the reviewed investigations, the surface roughness is clearly influenced by the feed rate, expecting higher values than the ones predicted by the theoretical equations. Besides, the increase of both the cutting speed and feed rate leads to a high tool wear. Likewise, the increase of the feed rate leads to higher machining forces. In general, the influence of the cutting speed and depth of cut is less evident. Regarding the machining parameters, usually their maximum values are fixed at low levels: 100 m/min, 0.35 mm/rev and 0.3 mm, for the cutting speed, feed rate and depth of cut, respectively.

This paper focuses on the structural design of screw tools in briquetting presses used for the production of solid, high quality, bio fuels. The primary objective is to analyse the screw tool geometry and determine a procedure for its design, specifically the theory involved with the pressing tool and force relations which are necessary for the verification of the proposed tool geometry and its strength analysis. In designing the main drive of the press, procedures for determining frictional performance of the screw press are used. Familiarity with the above mentioned procedures forms the basis for research into new tools in screw briquetting presses that will improve the service life and competitiveness of the technology.

The paper deals with the issue of magnetism and its use in mechanical engineering as well as in other industries. Transmission systems are rather frequently present in almost every technical system. The purpose of each transmission system is to transform energy, based on which its quality can be assessed.
The main objective of this paper is the structural design of a magnetic cycloid gearbox, a detailed description of transmission kinematic analysis, elaboration of calculation models for FEM analyses consisting of the analysis of gearing power relations and calculation of maximum torque the gearing is able to transform.

The Mg-5.6Gd-0.6Y-0.4Nd-0.2Zn-0.2Zr (wt. %) alloy was prepared by metal mold casting. Then the alloy was subjected to hot forging. The microstructure and mechanical properties of the solution-treated, hot-forged and aged alloy samples were studied. The affects of deformation processes on the microstructure and mechanical properties were discussed, and the strengthening mechanisms of alloy were also investigated. The results revealed that the coarse second phases distribute along the dendrite boundaries in the solution-treated alloy. After hot forging, the second phases were broken into small particles and the grains get uniformity. Tensile test results showed that the strength of alloy was greatly improved after hot deformation processes. The forged alloy showed remarkable age hardening response at aging temperature of 180°C. The peak hardness was obtained by the time of 72h. The ultimate tensile strength and yield strength of the peak-aged alloy were 275MPa, 181MPa at room temperature, and 209MPa, 127MPa at 300°C, respectively. The high mechanical properties were mainly attributed to the fine microstructure and fine dispersed metastable precipitates in the matrix.

Spatial measurement and evaluation of the surface profile parameters provide valuable and useful information about the relationship between the geometric characteristics of the surface and its functional properties. Evaluating the structure of surface area may help to explain a variety of problems in manufacturing technologies as it allows detailed quantitative study of geometric and dimensional changes of the surface profiles. AWJ cutting still generates unrevealed questions regarding interactions of the cutting material with the work-piece. The article presents experimental study of surface of steel material after AWJ cutting with usage of optical method that was selected as universal method that overcomes some of the shortcomings of contact methods.

The Zn-1.6Mg alloy was chosen because mechanical properties of this alloy are similar to human bones. It is necessary to describe corrosion behaviour of the Zn-1.6Mg alloy before using it for application as a biodegradable material. In this work, two types of corrosion rate measurements were used. One of them was an exposure test in model physiological solution marked as SBF (the simulated body fluid) and NaCl solution. The second method was measurement of potentiodynamic curves in the SBF and NaCl solutions. The aim of this work was to compare both methods and confirm similar trend of corrosion behaviour in model physiological solution (SBF and NaCl).

The industrial use of aluminium alloys has significantly increased in the last decades. Most machined parts are produced by cutting. Therefore, research in this field is quite important nowadays. Surface roughness is an extremely important quality parameter of a product, such as geometrical sizes and their tolerance. The authors in this article analysed the machinability of die-cast aluminium alloys with silicon often used in the industry. The turning experiments were made with different diamond tools edge geometry. The surface roughness obtained during turning was analysed in detail. Phenomenological models were created with which the surface roughness producing ability of the examined tools can be estimated in technological design.

This paper focuses on verification of experiment of thermoelastic stress analysis by using numerical solution. Thermoelastic stress analysis is noncontact technique to obtain thermograms, thermographic images of the stress fields, by using an infrared camera. In the elastic part experimental results can be used to determine the value of the first stress invariant under adiabatic conditions. The experimental part is dedicated to the postprocessing of the measured data. Numerical solution was performed by finite element method in two softwares: ANSYS and ABAQUS.

Aluminium, chromium, silver and other metal targets are often used for glass crystal coating in jewellery. The structure of targets strongly influences the quality of coating which leads to differences in their optical properties. The targets from two manufacturers were examined using scanning electron microscopy combined with EBSD with a goal to identify possible metallographic cause of defects arising on glass jewels.