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Machining of titanium is quite difficult and expensive. Heat generated during the process of cutting does not dissipate quickly, which affects tool life. In the last decade ultrafine-grained (UFG) titanium has emerged as an option for substitution for more expensive titanium alloys. Extreme grain refinement can be readily performed by severe plastic deformation techniques. Grain refinement of a material achieved in this way was shown to change its mechanical and physical properties. In the present study, the microstructure evolution and the shear band formation in chips of coarse grained and UFG titanium machined to different cutting speeds and feeding rates was investigated. It was demonstrated that an improvement in the machinability can be expected for UFG titanium.

Simulation of grinding is a topic of great interest due to the wide application of the process in contemporary industry. Up to date, several modelling methods have been utilized in order to accurately describe the complex phenomena taking place during grinding, the most common being the finite element method and artificial intelligence techniques, e.g. soft computing methods. The present paper proposes a new hybrid model for precision grinding, more specifically the combination of finite elements with neural networks. The model possesses the advantages of both the aforementioned methods, for the prediction of several grinding features that define the outcome of the process and the quality of the final product.

Piston parts of a shipborne labyrinth compressor are mainly composed of a piston and a coated piston rod. In recent years, many studies have shown that the vibration response of coating structure is significantly reduced. Because of the non-contact of the piston, the cylinder case and guide support entirely depends on the piston rod. The lateral jitter can be regarded as the vibration of cantilever beam. However there is no effective method to separate the contribution of hard-coating damping from the damping of composite system. In this paper, based on separating the damping contribution of hard coating, the method of creating the damping mechanism model of piston rod is studied. Firstly, the piston rod before and after coating are tested and the characteristic parameters of vibration, such as natural frequency, damping ratio, vibration response are acquired. Moreover, according to the analysis of the storage and dissipation energy in the uncoated and coated rod, the damping contribution of hard coating has been confirmed. Finally, the Oberst beam theory is adopted to create the damping mechanism model of piston rod which includes both material damping and viscous damping. The correctness of analytical model is also verified by the experiment results.

This work describes properties of newly developed Fe-Al-Si alloy for high-temperature applications. This alloy is a material composed of FeAl, FeSi a Fe3Al2Si3 intermetallic compounds, which was prepared by powder metallurgy using mechanical alloying and spark plasma sintering. The oxidation resistance at the temperatures of 800 and 1000 °C was described, as well as the mechanical properties up to 700 °C. During oxidation, the alloy covers by aluminium oxide layer, which protects it against further oxidation. Concerning the mechanical properties, the yield strength and ultimate compressive strength increase in the temperature interval of 400 - 500 °C.

Utility properties of forgings, particularly the mechanical ones, are among the primary aspects of interest to the customers of forge shops. These properties arise from internal structure whose evolution depends predominantly on the combination of parameters of deformation processes applied during forging, on the temperature profile during cooling and on the shape of the forged part. As microstructural evolution depends on the shape of the particular cross section of the forged part, an appreciable inhomogeneity of mechanical properties occurs in forgings. This article deals with observation of microstructural evolution in a chosen forged part, depending on cooling profiles of its various cross sections. The experimental programme of mechanical working and treatment of the forged part was based on the material-technological modelling approach. Microstructural evolution was studied using light and electron microscopic methods. Results of this analysis provided a basis for outlining optimization steps for mechanical working and treatment of the forged part.

Customer requirements represent the driving force in the market, dictating the directions of development, production and processing of forged parts. Meeting these requirements is of paramount importance to forge shops as a precondition for their continuing operation and competitiveness. Consequently, optimization of manufacturing operations and their rapid response to market requirements are necessary for the forge shops to survive. However, any production stoppage for optimization results in extra costs. Forge shops thus strive to carry out optimization in as few steps as possible and within the shortest possible timeframe. A viable solution emerges in the form of material-technological modelling which involves laboratory-based optimization taking place away from the forge shop without any constraints on the production operations. This paper deals with selection of a material for a forged part to be controlled-cooled from the finishing temperature to substitute a C45-steel part treated by normalizing. One criterion was that the entire forged part should contain ferritic-pearlitic microstructure.

Application of biopolymer materials is currently a rising trend. However, many problems are often encountered when evaluating and describing their mechanical properties. The present article will describe a procedure for finding a so-called effective modulus of elasticity of a biopolymer material having the shape of a thin string with a diameter of about 100 μm.
Subsequently, there are not only problems in the actual evaluation of the tensile test (which will be demonstrated by the assembled 3D model), but also when the sample is sampled, which is decisive for finding an efficient module. The article will deal with the methodology of sample squeezing into the specially developed product, the determination of an elastic modulus from the tensile test and the behaviour of the sample when the strength limit is exceeded, which will be captured and subsequently evaluated by the high-speed camera system.

The rapidly solidified aluminium alloy with slowly diffusing transition metals (iron, chromium) prepared by powder metallurgy techniques is characterized by higher thermal stability in comparison with other common aluminium alloys thanks to hardening of dispersed intermetallic phases. The solubility of transition metals in aluminium is increased by rapid solidification, however, their content, in the alloy, is simultaneously significantly reduced due to the formation of hard and brittle intermetallic phases, which lessen plasticity, ductility, and strength of the material. This work is devoted to the description of a microstructure of AlCr6Fe2Si1 alloy prepared by gas atomization followed by consolidation by High-Pressure Spark Plasma Sintering, and comparison of the influence of various sintering conditions on the microstructure of alloy. The low-porosity compacted alloys are formed by quasi-crystalline phase Al95Fe4Cr, the crystalline phase Al13Cr2, and Al80Cr13.5Fe6.5 in the aluminium matrix. They are formed by powder particles with the different internal morphology of intermetallic phases (spherical clusters or snowflakes).

Biological soft tissue is a non-linear and viscoelastic material and its mechanical properties can greatly affect quality of life. Many external mechanical factors can alter the tissue, for example the tissue of talipes equinovarus congenitus, also known as clubfoot, which is the most frequent congenital deformity affecting lower extremities with pathological changes of connective tissue. In clubfoot, the presence of disc-like mass of fibrous tissue, resembling intervertebral disc tissue, is described to be between the medial malleolus and the medial side of the navicular bone. The clubfoot tissue is often referred to be stiffer or rigid by clinicians, or it is referred to as contracted and less contracted tissue, however relevant evidence about mechanical properties is missing. Therefore, the description "disc-like" is informing only about relative mechanical properties of clubfoot tissue. We aim to prepare methodical approach to quantify mechanical properties of biological tissue with uniaxial tensile stress-relaxation test, in order to help clinicians and scientist to identify precisely the mechanical properties of normal and pathological tissue and their structural behaviour during mechanical testing. In this study, we test and tune the uniaxial tensile stress-relaxation test on biological tissue with high content of connective tissue such as collagen. The model tissue is porcine pericardium. The tissue has clear collagen fibres aligning parallel to the force applied. Modulus of elasticity measured here is comparable to other studies.

Using of cutting inserts is currently a normal part of the manufacturing process. The article deals with analysis of tool wear after machining at one selected cutting insert. Evaluation of this insert was made by electron microscopy. There was used SEM and EDS analysis. For this purpose was used scanning electron microscope Tescan Vega 3 and EDS analyzer Bruker 16 which is part of this microscope. These analysis can provide a good picture of the structure and construction of inserts, their composition and for situation on the insert after machining. This may assist in finding suitable cutting conditions. As experimental material the hardened steel class 16MnCr5 according to EN 10027-1 has been machining. SEM images of final tool wear of the cutting insert were recorded. The reason was to map the tool wear state after machining using electron microscopy to give a better view of the situation. These analyzes were performed in other experiments performed at the Faculty of Mechanical Engineering at Jan Evangelista Purkyně University in Ústí nad Labem.

Porous titanium-based alloys are very promising materials for medical implants due to their low density and easy osseointegration. In addition, proper porosity and pore size allow adjusting the mechanical properties of implants to values closer to human bone. The aim of this work is to prepare porous metallic biomaterials based on Ti-Si alloys with defined porosity for surgical and dental applications. Alloys were prepared by powder metallurgy using reactive sintering. Best results reached TiSi5 and TiSi10 alloys. The TiSi5 alloy contains smaller pores and achieves lower porosity values. This alloy also has the highest yield strength in compression from these alloys. On the other hand, the TiSi10 alloy is more porous and it is likely to be more suitable for osseointegration.

Viscoelastic behaviour of materials is connected with transformation of mechanical energy into heat, which is a measure of a material structural damping. Viscoelastic properties of materials are described by different quantities, e.g. by loss modulus, storage modulus and loss factor. They depend on material type, its structure, excitation frequency, temperature, relative humidity etc. Damping properties were experimentally measured by means of the forced oscillation method. The purpose of the paper was to investigate viscoelastic damping properties of different polymer materials like PE, PP, ABS or rubber. There were studied different factors that have an influence on viscoelastic damping properties of the investigated polymer materials under dynamic loading, mainly the effect of operating temperature, excitation frequency, sample deformation and rubber composition.

Ti-Al-Si alloys excel with their low density and good resistance against high-temperature oxidation in comparison with so far commonly used nickel alloys. Silicon in Ti-Al-Si alloys has significant positive effect on high-temperature oxidation due to increasing adhesion of oxide layer. The TiAl20Si20 alloy was evaluated as the best alloy from tested ones, because its oxide layer protected very well the basic material and TiAl20Si20 achieved good hardness after 400 hours of annealing.

The requirement for high strength and ductility is usually associated with martensitic microstructure with a certain amount of retained austenite. One of the innovative heat treatment processes that can lead to such microstructure is the Q&P process (Quenching and Partitioning). It can produce microstructures consisting of martensite and a certain amount of retained austenite, which exhibit strengths above 2000 MPa and elongation levels of more than 10%. The objective of this research was to explore the effects of the cooling rate in the Q&P process and evaluate the effects of various microstructure constituents on mechanical properties of high-strength steels. Three newly-created experimental steels, which contained 0.43% carbon and had reduced Ms temperatures thanks to manganese addition, were subjected to several heat treatment routes which involved various cooling rates. The cooling rates were chosen on the basis of calculations using the JMatPro software and earlier results. It was found that by varying the cooling rate one can obtain various mixed microstructures and a wide range of mechanical properties. The strengths were in the range of 1200-2300 MPa and A5mm elongation levels were up to 18%. Because the amount of retained austenite has a considerable impact on the resulting mechanical properties, it was measured by means of X-ray diffraction.

The paper deals with the design of a special machining tool for efficient production of detail on the T-groove of the clamping part. The introductory part of the paper is focused on introducing the Czech company. The practical part of the paper deals with the analysis of the existing state of machining of the clamping body and of the production of the T-groove detail and proposes an innovative solution in the form of more efficient machining process (partial production modification), which consists in the development and production of a special tool with replaceable inserts. The main reason for this partial modification is a significant reduction in unit machine time in the production of the T-groove detail on clamp body parts. Part of the contribution is in the process of streamlining the innovation made in the form of changes to the manufacturing process and the design of the cutting conditions required to produce the T-groove detail on the clamp body parts. The contribution is completed by a technical and economic evaluation, which is related to the analysis and comparison of both proposed production variants in terms of machine times, tool consumption / replaceable inserts and total production costs for the T-groove detail production on the clamp body parts.

One of the problems in machining Al alloys represents machinability of these materials. Machinability is a characterised by several characteristics. One of these characteristics is a cutting temperature. This paper is focused on the effect of selected modifiers in AlSi7Mg0.3 alloy on this temperature. Several variants of this material modified by strontium, calcium and antimony are used. All these materials are compared with non-modified alloy. Moulded castings of non-modified alloy and for each modified variant were made. Gravity-die castings into a metal mould with a thermal insulation were used.

The aim of this study was to create a mathematical model of the RRR anthropomorphic mechanism for a 2D biomechanical analysis of a deep squat and related forms of movement. The segment stick model is designed to diagnose the movement with sagittal plan symmetry. Based on the input data from kinematic and dynamometric analysis, and from the anthropometric data of the monitored person, it is possible to estimate the resulting momentum of the forces acting on the main joints of the lower body. The technology may be applied in analysing deep squats, studying the dynamics of vertical reflection as well as in the biomechanical analysis of related forms of movement (e.g. standing-up, squatting with a dumbbell, skiing in downhill posture, etc.). The derived motion equations may be used to analyse the dynamics of the movement of anthropomorphic or mechatronic systems with the same geometry.

The article deals with the optimization and modernization of assembly systems by creating models in the simulation software. The creation of digital models is a current trend in enterprise digitization called Industry 4.0. The Tecnomatix Plant Simulation environment allows you to create a virtual model of a real assembly line with the input of its basic production parameters. To perform the analysis, 8 real assembly lines were used, with an average of 15 workplaces, which were integrated into one universal line by means of simulation. The aim was to analyse the effectiveness of the proposed modernization universal assembly line using the generated statistical data.

This work deals with the microstructure of TiAl15Si15 intermetallic compound, which can be used as a high-temperature low-weight material especially for the automotive and aerospace industry. A combination of high mechanical properties, good oxidation resistance and low density of this material is a good potential for use this alloy in many applications. The TiAl15Si15 alloy was prepared by different techniques of powder metallurgy. In this work, microstructure after reactive sintering, reactive sintering in a combination of Spark Plasma Sintering and mechanical alloying followed by Spark Plasma Sintering was described. The results were compared with the same alloy prepared by arc melting.

Several models of FDM machines, characterized by different architecture and hardware components, have flooded the market in the last 5 years. As a result, given the high sensitivity of FDM to the specific machine characteristics, the search for optimal printing parameters is a renown problem. This two-parts paper proposes an easy-to-follow and low-cost procedure for the characterization of any given FDM machine. The method allows the evaluation of the effects of a wide selection of FDM process parameters on the quality of 3D printed parts. The first part focuses on the definition of a series of metrics to be measured on a series of test prints to evaluate the quality of the produced parts. Specifically, several effects are considered: dimensional accuracy, small details, overhang surfaces, ability of printing small holes/thin extrusions and overall quality of the prints. The evaluation of seven quality parameters on a single print is made possible thanks to: i) a specifically designed specimen that is made available to the user and ii) a rigorous and repeatable measurement procedure, which are both discussed in the first part of the paper. The second part presents the characterization procedure, the statistical tools used in the experimentation and provides guidelines to be used for the characterization of any FDM machine. The whole procedure is tested on a desktop FDM machine to demonstrate obtainable results.

The paper deals with the proposal for the production of an assistance brake for a mechanical wheelchair, which will help the wheelchair users to move in the course of overcoming barrier-free and partially barrier obstacles. The introductory part of the contribution characterizes the basic requirements of the brake for a mechanical wheelchair, especially from a legal point of view and in terms of their safety. The practical part of the paper deals with the production of a prototype pair of assistance brakes in school conditions (workshop C2 of the Institute of Mechanical Engineering, Faculty of Mechanical Engineering, Brno University of Technology) using conventional machining technology (brake body production) and 3D printing technology (braking segment production). Part of the practical part also requires testing in typical / real wheelchair conditions. The contribution is completed by the technical and economic evaluation of the prototype pair of assistance brakes, which is related to the calculation of the total cost of their production.

The aim of this article is to calculate and compare the modal properties of the frame of the standard and modified freight wagon bogie design. Analysed frames represent the main support parts of the bogie, which are most often used in the Central Europe region. Determination of the modal properties belongs to the fundamental but very important step in the engineering design. In our case, modal analyses of bogie frames structures were carried out using the Finite Element Method. In order to perform numerical calculations based on FEM approach, Ansys package was used. Modal analyses of individual parts as well as substructures of rail vehicles is an inseparable part of the rail vehicles design process. In this article theoretical and practical consequences of obtained results from the modal analysis, i.e. eigenmodes and eigenfrequences of the analysed part of the bogie on its dynamic properties are presented.

Aiming at a kind of grinding head of high-speed precision roll grinder, its structure characteristics and heat source characteristics are analysed, and the characteristics of heat source is calculated. On these bases, the weakness of grinding thermal characteristics is found through the numerical analysis of thermal performance of roll grinding head, facing the thermal error of sensitive area, optimization method which unites multi objective and single objective are adopted to optimize the thrust oil film bearing of the roll grinding head, after that numerical analysis of thermal performance of roll grinding head is analysed. Analysis results show as follows: temperature of the optimized oil film thrust bearing is improved obviously. The oil film performance between the bearing and the main shaft is stability, and it has had effective prevent the phenomenon of metal dry friction happening. As a result, the grinding accuracy of the grinding roll is effectively improved.

Various industry sectors are using advanced high-strength steels nowadays. Application of these steels are often constrained by the capabilities of their manufacturing and processing technologies. To deliver the required properties, advanced high-strength steels must possess the prescribed microstructures which can be achieved by specific heat treatment routes, such as intercritical annealing or the Q&P process. Difficulties, however, arise in these materials' joining, and welding in particular. Welding profoundly affects the microstructure and mechanical properties of the product due to the amount of heat input and subsequent rapid cooling. For these reasons, laser welding and electron beam welding tests were carried out on experimental 42SiCr steel. Prior to welding, the material was treated using two different Q&P process sequences and one conventional quenching sequence. The weld metal, the heat affected zone and the base material were examined by metallographic methods and the impact of the introduced heat on the microstructure was studied.

This article presents the study of the influence of the bias voltage and CH4/N2 gas ratio on the structure and chemical composition of Cr(C,N) coatings. The coatings were deposited by cathodic arc evaporation of pure Cr (99.99 %) cathode under an atmosphere of a mixture of CH4 and N2 gasses at the low deposition temperature of 300 ˚C. The ratio of reactive gasses was changed from 0 to 100 %. Energy-dispersive spectroscopy showed a linear dependence of resulting C/N ratio on the process gas ratio. The roughness of layers prepared from a mixture of process gasses is higher compared to pure gasses.

Right after the ferrous alloys, aluminium alloys represent the most wide spread used constructional materials of these days. The main reason of such utilization rests mainly in their specific weight, availability, good mechanical properties and corrosion resistance. To enhance their mechanical properties is there, at majority of technically used aluminium alloys, applied thermal treatment. Wrought aluminium alloys are generally processed after the solution annealing and before their natural or artificial hardening. However, in light of the formability is the own ageing process quite undesirable due to strong decrease of the material formability properties. In this paper is evaluated the time change of the aluminium alloy AW-2024 mechanical properties after the solution annealing in dependence on different storage time before forming. Such change of the mechanical properties was evaluated by means of the static tensile test.

This article describes the formation of a composite coating in a polymer matrix on an aluminum alloy. It is a PMMA coating (polymethylmethacrylate) with the addition of TiO2 particles. Working with these particles requires not only safety but also a suitable preparation process to obtain particles of suitable size, their subsequent homogeneous distribution in the coating (particles of this size are influenced by electrostatically attractive forces and have a strong tendency to aggravate). The first part describes the material used, sample preparation and coating process, surface roughness measurement, SEM and EDS analysis of selected samples. The aim of the research is to find out whether it is possible to use dipping and brushing techniques when coating Al-Si alloys with polymeric materials. Consequently, what can be achieved is the roughness of the surface of the coated part compared to the uncoated surface (at different particle concentrations in the spin) and the distribution of TiO2 particles on the surface of the sample.

Direct Metal Laser Sintering (DMLS) is a method of Metal Additive Manufacturing which builds metal parts in a layer-by-layer procedure based on a CAD template. This method is diametrically different from machining methods such as turning or milling. Nowadays, DMLS is used for rapid manufacturing of complex metal parts. However, these products do not meet the requirements of high accuracy and surface quality. This paper deals with factors that are involved in the dimensional precision of DMLS production. The purpose of the Scale and Beam offset correction coefficients are described in the paper. Practical experiments and measurements were carried out and are presented here. Usual production accuracy was observed.

In this paper we observe dynamic mechanical properties of rubber mixtures - standard and CNT, where in the mixture CNT were dispersed nanoparticles - shape of carbon nanotubes (CNT). We used the testes apparatus by PerkinElmer "PYRIS Diamond Dynamic Mechanical Analyzer" for measuring mechanical properties. Dynamic mechanical analysis (DMA) is a technique used to study and characterize materials. It is the most useful for studying the viscoelastic behavior of polymers. A sinusoidal stress is applied and the strain in the material is measured, allowing one to determine the complex modulus. The temperature of the sample and the frequency of the stress are often varied, leading to variations in the complex modulus. Dynamic mechanical properties of tested mixtures are evaluated using frequency and thermal dependence. Dynamical tensile test we did during temperature program from 20 °C to 100 °C. We gradually applied frequencies 0.01 Hz, 0.5 Hz, 1 Hz, 10 Hz, 20 Hz and 50 Hz.

This paper describes selected aspects of design, optimization and manufacturing process of racing car's upright. Uprights described in this paper are formula student car's uprights. Formula Student is an international competition between university students, which must design and build a new prototype of the car each year, according to the FSAE rules. Uprights for most racing cars, formula student cars included, must meet wide specter of different requirements, like minimal weight, minimal stiffness etc. The first part of this contribution is concerned to design requirements and boundary conditions definition problematics like different uprights types. The following parts describe the material selection and possible optimization for the design and manufacture of the new uprights for the formula car. Manufacturing and final assembly of the part will be described.