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Repairs of branch connections defects on high-pressure pipelines allied to gas-escape are nowadays difficult processes. The reason is necessity of performing sections of damaged pipeline that is connected with transport medium layoff or with using technology of by-pass installing around damaged part of pipeline. In article, a concept of technology of branch connections repairing by split pressure sleeve is presented, which is in recent times realised only at straight sections of pipelines. Concept consist of split sleeve design along with wall thickness optimization in simulation software ANSYS. Concept of internal space of sleeve sealing up from welding workspace using appropriate seals placed at its sealant carriers is presented, too. Dimensions, material of carriers and sealant location were designed according to experimental measure of temperature, together with subsequent validation of heat transfer by numerical simulation in software SYSWELD. Described repairing method concept seems to be an appropriate alternative of branch connection repairing that allows fast and safe correction with lowered operational costs on realisation of repair and possibility of speeding-up and simplifying emergency conditions solution.

This paper deals with the preparation of highly dense Ni-Ti alloys with addition of alloying elements like iron, vanadium and zirconium. The alloying elements were added in an amount of 5 wt. % into Ni-Ti46 wt. % powder mixture. The prealloyed NiTiX5 powder was prepared by the self-propagating high-temperature synthesis with following milling of the product. The prealloyed powder was consolidated by spark plasma sintering. The microstructures, mechanical properties and abrasive wear of prepared alloys were investigated. The results were compared with Ni-Ti and NiTiX alloys and other materials prepared by powder metallurgy. The undesirable changes in microstructures (formation of the Ti2Ni and Ni3Ti phases), the increase of hardness and abrasive wear resistance were found during milling and spark plasma sintering.

Results of an experimental research of friction coefficient in "alumina ceramics - quartz glass" friction pair are presented. The research with pin on disc test configuration using SRV-III test machine was carried out at loads from 10 to 1000 N, constant sliding velocities 5 mm/s; ambient temperature 23°C and relative humidity 30%. The obtained results reveal that in general, friction coefficient for "alumina ceramics - quartz glass" pair decreases with the increase in normal load. It is shown that the obtained friction coefficients values at the normal force from 100 to 1000 N for the given experimental conditions can be used to pre-estimate the interference fits in "alumina ceramics - quartz glass" friction pairs.

New concept for pressure testing samples has been designed based on previous experiments which investigated the maximum load capacity of a Schoen Gyroid. This pre-experiment pointed to the possible lack of measurements and newly designed pressure samples intended to improve measurement accuracy. This paper focuses on the manufacturability of the designed samples made by selective laser melting, which is able to produce complex metal parts using support structures. However, removing the support structures from a porous core is impractical. In this context, the ability to substitute supporting structures by a Schoen lattice structure is also marginally dealt with. The paper concludes with the benefits of the optimized pressure samples over the old concept. An increased maximum load capacity was achieved by the addition of contact plates, which constrain the strut ends.

Microstructure and mechanical properties of powder metallurgically prepared AlSi24Fe3 alloy are presented in this article. The alloy was prepared in form of rapidly solidified ribbons by melt spinning process. Consequently, the ribbons were crushed into powder in a ball mill and compacted by spark plasma sintering. Grain size of prepared alloy was less than 1 μm, Vickers hardness HV0.1 reached value 214, yield strength and ultimate compressive strength were 611 and 778 MPa, respectively. To obtain material with possible self-healing proprerties, it was necessary to enrich material by fine dispersed Ag2Al particles. The AlSi24Fe3 powder particles were sputtered by 5 nm layer of silver before sintering. The total amount of Ag in bulk sample was approximately 0.1 wt. %. The microstructure of Ag containing alloy was comparable to the basic one. The Ag nanoparticles were present on several particle boundaries. The influence of Ag presence on Vickers hardness of the material was not observed, as the values HV0.1 was 212. After a heat treatment (450 °C/ 1h), silver transformed to equilibrial Ag2Al phase, present in material in form of nanoparticles no more decorating strictly the particles boundaries.

Plastic injection process is one of the techniques used to manufacture plastic products. The technique is widely used due to its higher and faster production capacity and low cost. However, production process problems are often found, one of which is inappropriate process parameters settings, which may cause product defects. This paper presents a method using combination of Taguchi method, Moldflow simulation and PSO to optimize plastic injection molding process parameters. Moldflow simulations were run to obtain volumetric shrinkage values resulting from each combination of parameters setting selected by means of OA. In adopting S/N ratio technique of the Taguchi method, the study adhered to the principle of "the smaller the better". The ANOVA method was also used to analyze the effect of each process parameter on volumetric shrinkage and a regression analysis was used to establish the equation used for the application of the PSO method to optimize plastic injection process parameters. This method was applied for the production of number plate brackets from PP AZ564 material. The study concluded that the application of the combined Taguchi-Moldflow-PSO method could reduce volumetric shrinkage from 6.05% to 4.24%.

The paper presents solution to random generation of fibers in composite materials for homogenization using representative volume. Randomly positioned fibers with random diameters of constrained sizes are generated within predefined representative volume, while minimal gap between fibers and volume ratio of fibers in the matrix is maintained. The problem of random generation is solved as an optimization problem using a custom memetic algorithm designed by the authors. A comparative study was performed, comparing performance of memetic algorithm and genetic algorithm.

The current manufacturing production is characterised by increasing level of automation, emerging of the new light-weight and high-stiff materials that are technologically difficult to produce. These trends have significant impact on production productivity. The automation has brought significant reduction of non-productive time (fast workpiece and tool exchange, automatic control of product quality during technological process). In this situation, the machining time becomes the limiting factor. In present, the reducing of the machining time is possible to make only by either significant changes in conventional technologies or application of new technological principle. However, these secondary solutions in some production section are not sufficient because it requires a global solution. An example of un-equal time continuity in link production is fact that one pressing machine with the time per one piece in seconds can supply dozen of lathes with the time per one piece in minutes. The paper provides also the proposal to the productivity increase of critical technologies as turning and milling.

In the aerospace industry, the nickel-based superalloys are often used due to their ability to withstand extreme conditions. They find their use particularly as turbine blades in jet engines. An important example of this type of superalloy is INCONEL. This construction material must meet a wide range of complex requirements with regard to its properties and technological and operational characteristics that are required by the heavy duty in extreme conditions.
The INCONEL Superalloys represent multicomponent and multiphase materials with their complex alloying base and structure with distinct dendritic segregations. Their long life and reliability in operation are directly related to the microstructure, or to its stability in a long-term operational application, respectively.
The presented work deals with the evaluation of microstructural parameters at two variants of cast superalloy INCONEL 713LC, applying the light microscopy and electron microscopy, including the fractographic analysis.

Current contribution contains of results of experimental measurements performed within the determination of initial raw feedstock materials moisture content and its influence on final properties of subsequently produced briquettes. A birch wood chips samples with five different moisture contents, specifically 5.0%, 7.6%, 16.7%, 19.0% and 27.7%, were used for experimental investigations. Investigated briquette samples were produced by hydraulic high-pressure briquetting press Briklis, type BrikStar 30-12 with cylindrical pressing chamber of 50 mm. All investigated briquette samples were produced under the same conditions with constant adjustment of all parameters of used briquetting press. A basic physical-mechanical properties of investigated briquette samples were used as a criteria of investigations evaluation. All measured values were subjected to the statistical analysis. Final evaluation of measured values indicated that best results were achieved by briquette samples produced from feedstock material with moisture content equal to 7.6%. Evaluation of current investigation also proved that if moisture content was higher or lower, the quality of produced briquette samples decreased.

One of the roles of mechanical engineering is to improve the efficiency and performance of mechanical parts. Cellular lattice structures can be a good tool for achieving this target. This paper focuses on a specific kind of lattice structure which is composed of cells called a Schoen Gyroid. Samples containing this porous structure were subjected to a series of pressure tests. The main aim is to find the possible influence of certain factors on the accuracy of the load capacity. The selected factors are the friction between the porous sample and the testing device, then the matrix size of the samples. The discovered relationships of these factors on the accuracy were used for the final pressure test where the effect of changing strut thickness on load capacity is measured.

This article deals with comparison of corrosion resistance of 42CrMo4 steel used for breech mechanism in the armament production. Increasing of demands on materials used for armament production and in other industrial application leads to the innovation of technologies in the field of surface treatment especially wear resistance, surface hardness, running-in properties and corrosion resistance. For the evaluation of experimental NSS corrosion resistance tests samples of 42CrMo4 steel were compared with plasma nitrided and nitrocarburized one. Individual 42CrMo4 steel samples were subsequently metallographically evaluated and characterized by hardness and microhardness measuring. The results and comparison of corrosion resistance of not-surface treated steel samples with plasma nitrided and nitrocarburized showed significant differences of corrosion rate. Due to different plasma nitriding conditions, there are corrosion resistance differences evident between the plasma nitrided steel samples as well. The corrosion resistance evaluation is supplemented by the surface corrosion-free surfaces evaluation using the laser confocal microscopy.

This paper describes the conception of vehicle interior which can help decrease the injury risk of unbelted passenger. This paper is primarily aimed to the field of rail vehicles, but the results are useful for more transportation industries. Some computer simulations for passive safety performance assessment were conducted in previous years. The FE models of the interiors based on data from actually operated vehicles were prepared for this purpose. The newly prepared simulations are close to the real interior models. Combinations of rigid walls were used for modelling. Each model contains a short python code which allows change of interior disposition. This approach is close to an optimisation process. The main goal is to compare all possible configurations of interior. In practise it is usually obvious which change can improve the passive safety, but with numerical approach is possible to find structures with unknown influences. The simulations were performed in software environment PAM-CRASH. It is used a dummy Multibody model of the human body ARB Hybrid III 50th percentile.

Comprehensively considering the analysis results of the microstructure, hardness and tensile properties, different zones of a component for aircraft applications manufactured through hot stretch forming were studied. The differential thermomechanical story of each studied zone of the forging was taken into account. The results reveal that the different zones strain hardened in function of the degree of the strain and strain rate experienced during the forming, with the zones most stressed at the higher strain rate showing the best tensile properties and a loss of ductility. This phenomenon is not coupled with a visible change into the microstructure morphology of the processed material.

Reforming obsolete technologies, increasing production of new machines and devices are impossible without modern and reliable instrumentation. The high structural complexity of the manufactured parts creates problems for the use of a blade tool that, along with high hardness, has considerable brittleness. As a rule, the processing of intermittent surfaces by turning is accompanied by chipping of the cutting edges.
The disadvantages of alternative grinding technologies are the high cost of equipment, low productivity, as well as the problems of forming the required quality parameters of the surface layer due to the specificity of operation of the grinding tool.
The solutions protected by patents of the Russian Federation, allowing to exclude negative factors of intermitted cutting are offered. The scientific novelty of the decisions made is to give the damping tool a special position that excludes negative interaction between sharp tip of cutting element and intermittent surface, which provides the possibility of stable operation of brittle tool material on the basis of the developed mechanism for controlling the position of the cutter tip.

The utilisation of pure molybdenum in high-temperature applications in a vacuum requires very precise machining. Considering the fact that conventional machining methods do not achieve the required geometrical and dimensional accuracy in several cases, it is necessary to use the unconventional technology of wire electrical discharge machining (WEDM). This study aims at analysing the surface and subsurface layer of pure molybdenum after WEDM in terms of the occurrence of defects. Profile and areal parameters were evaluated by means of a contact 3D profilometer. The occurrence of individual defects both on the surface and underneath it was studied by means of the methods of electron microscopy and focused ion beam (FIB). Furthermore, the local chemical composition of the surface of the workpiece (EDX) was determined.

The plasma nitriding technology was applied on the turbocharger stator wheel. Martensitic stainless steel X12Cr13 was choosen for the experiment. The influence of plasma nitriding process on the corrosion resistance of selected steel was investigated. The chemical composition of selected steel was verified using the Q4 TASMAN device. After plasma cleaning procedure was plasma nitriding process performed using two stage nitriding procedure. The microstructure and mechanical properties of the nitride layers were studied using optical and laser confocal microscopy and hardness testing. The depths of plasma nitride layers were also estimated using cross-sectional microhardness profiles measuring. The corrosion resistance of plasma nitrided X12Cr13 steel samples were evaluated in a 5 % neutral sodium chloride solution (NSS) in accordance with ISO 9227 standard in the VLM GmbH SAL 400-FL corrosion chamber and visually verified. Microhardness and surface hardness of experimental samples were significantly increased, but the corrosion resistance significantly decreased.

Magnesium is biocompatible metal with mechanical properties similar to the bone tissue. Therefore it is suitable metal for biodegradable implants. There are high demands on mechanical and corrosion properties of materials for such use. Pure magnesium is usually characterized by poor properties which have to be improved. Properties are usually enhanced by alloying elements. However those elements are usually not biocompatible. Alternative way to improve both mechanical and corrosion properties is using composite materials. Reinforcement should improve mechanical properties and reduce corrosion rate by barrier effect. In present work, composite material with magnesium matrix and CaCO3 reinforcement was prepared. The structure, hardness, compressive mechanical properties and corrosion properties are characterized.

We need to create appropriate and effective numerical (FEM) model to optimize properties of a composite product. The creation and evaluation of an efficient numerical model that could be used for an analysis of layered composite is the aim of this work. The model has to be able to take into account the properties and layout of the individual layers and must allow effective change of these parameters; thickness, material and number of layers especially. Various models of the same product are created and compared. The models differ in the type of used FEM elements. The results of models (deformation primarily) were compared with the result of analytical computation. Further, time and computational requirements of individual models are also evaluated. Element types used for investigated models are: 1D elements, 2D plane stress solid elements, 2D plane strain solid elements and shell elements. Models created form 1D and shell elements showed a close agreement with the analytical solution, and they provide the appropriate tools for the definition of layered structures and for the analysis of results.

Ride of vehicles along curved track is a serious technical problem, which for the long term requires attention of vehicle engineers as well as track designers. It is especially interesting to observe behavior of tram cars passing a curved track, because they should be able to pass arcs up to 17 meter radius. Ride of a vehicle along such strongly curved track is nowadays accompanied by significant wear in rail-wheel contact, increased bogie and track stress and by generation of noise. One of the key causes of this unfavorable phenomenon is an increase of slip velocities in rail-wheel contact. This paper is based on simulation analysis, which compares different ways of minimizing slip velocities and thus mitigating the impacts of passing vehicles on the track as well as on the car itself. Bogies with and without wheelset steer possibility were analyzed. Both bogies were also analyzed with wheel profiles of different delta R function course.

Manufacture of new parts of machineries, devices, etc., especially in engineering and metallurgy requires machining of the feedstock in a mechanical way. During machining occurs immediate contact between the tested specimen and the tool and in their mutual relative movement of friction and wear. One of the possible variants how to eliminate this fact is the application of process fluids during machining.
Currently, we are trying to simulate long-term testing by laboratory testing called tribology. The experiment presents friction between two materials that are under real sliding contact. This article examines the tribological characteristics between two materials (tool - ball and workpiece material - disc). The paper contains findings when examining process fluids by tribological test Ball - on - disc, this test is currently used in practice, very widespread, this test can imitate various operations of cutting machining. This paper deals with the evaluation of tribological properties (the coefficient of friction, wear of disc and wear of ball) between the ball from ceramic material Si3N4 and the test material (stainless steel X5CrNi18-10, EN 10088-3 and steel commonly used in engineering 16MnCr5, EN 10084-94) by using two kinds of process fluids.

This study presents the Resistance Spot Welding (RSW) process of Deep Drawing Steel (DDS) optimization using Response Surface Methodology (RSM) and Simulated Annealing (SA). The RSW process was optimized to obtain the maximum shear force the DDS can withstand. The experiment was conducted under various DDS thickness, welding time and welding current. The experimental processes were conducted using L16 orthogonal array, which has nine rows. The processed DDS was tested using tensile testing machine which will generate the amount of shear force that it can withstand. RSM is first used to develop a suitable mathematical model. The model was tested using Analysis of Variance. From the test result, the model then was used as the objective function of SA. Based on the result, the maximum shear force can be well predicted, which leads to reduced cost and improved welding quality.

This paper deals with the creation of a computational model of a particular cable manipulator composed of a rigid manipulator with three degrees of freedom and a platform driven by four fibers. Each fiber is led over a pulley and is driven by a linear motor, which can be controlled. The multibody dynamics approach is a suitable way in order to create the manipulator model. The most common cable modelling techniques are summarized in this paper and then the computational model of the cable manipulator QuadroSphere is created using MSC.Adams software. The computational model verification is done using the modal analysis of linearized model and the experimental modal analysis on the real set up. Further results of various numerical simulations are presented and their utilization is discussed.

The aim of the research was to evaluate the lapping length, the adhesive bonded surface treatment and the influence of the filler in the form of the aluminium microparticles on the adhesive bond strength. The alloy AlCu4Mg was the adhesive bonded material bonded by means of a two-component epoxy adhesive used in construction of machines. The filler in a form of aluminium microparticles was added into the adhesive. Laboratory experiments were performed on normalized testing samples of alloy AlCu4Mg prepared under standard ČSN EN 1465. Within the research three various treatments of the adhesive bonded surface were evaluated, i.e. without the surface treatment (WT), mechanical treatment of the surface (MT) and mechanical and chemical treatment of the surface (MCHT). The adhesive bonds without the adhesive bonded surface treatment (marked as WT) reach the smallest adhesive bond strength. When adding the filler in the form of aluminium microparticles (10 vol. %) the adhesive bond strength was increased of about 12%.

New types of process fluids is very broad. Drilling with constant feed force represents the experiment that follows different properties and effects in machining. The main aim of this scientific paper is to assess the speed of drilling holes by the drilling technology-constant feed force- with the drilling cutting tools made of uncoated high speed steel. Eleven different process fluids were compared used the during the experiment. There were compared eleven different process fluids. In the context of the thesis more process fluids from global suppliers have been tested. In the process of experiments there were used twist drills of high speed steel type HSS, ČSN 221121, ø 8 mm, without coating. Steel samples were 16MnCr5, according to EN 10084-94. During the experiment there was used drilling of holes by hand feed drill machine V 20 that was modified with the mechanical switch and there was also stopwatch. Testing of process fluids in chip machining has been going on at the Department of machining and assembly of the Technical University of Liberec for many years.

When constructing traffic means, agricultural machines etc. it is necessary to create a bond, namely from thin semi-products, i.e. sheets of metal. Namely light and strong materials such as e.g. aluminium alloys EN AW 2024 T3 (AlCu4Mgl) are used in the constructions. A research namely on the adhesive bonded surface treatment is necessary at a rise of the quality adhesive bond. The aim of the research is an evaluation of the adhesive bonded surface treatment of the aluminium alloy EN AW 2024 T3 (AlCu4Mg1) by means of mechanical tests and a surface analysis by means of SEM. A cyclic degradation loading of the adhesive bond after exposing the adhesive bonds to increased and decreased temperatures, i.e. in the interval -40 to 70 °C in a programmable climatic chamber MKF240 and connected adhesive bonded surface treatments were evaluated within the research. The adhesive bonded surface treatment was of the positive influence on the strength and the elongation of the adhesive bond and it increased the resistance to the cyclic acting of the degradation environment at the same time.

The aim of the paper is to compare a tensile strength and an elongation at break of the sandwich materials with different cores created with the polymeric composite mixture at simultaneous acting of the cyclic degradation. The sheet S235J0 is the face. The core of the sandwich panel is from the structural two-component adhesive, from the composite material based on the microparticles of the glass-bead, the rubber and the textile microfibre waste from the tyre recyclation and the rubber particle waste from the tyre recyclation. Namely the secondary raw materials based on the textile microfibres are difficult to utilize in another processing. This research showed one of prospective possibilities of the material utilization of this secondary raw material. The highest tensile strength of the sandwich materials is reached with the core from the composite material on the glass-bead base. The significant fall of the tensile strength of the sandwich materials was measured at the material with the core based on the rubber and textile microfibre waste from the tyre recyclation. The elongation at break was not almost changed. The core crackled at lower loading at first. The face tolerated higher loading.

The use of cutting fluid increases the tool life and reduces the roughness of the machined surface. However, during the machining the oil from the hydraulic system of the machine often gets into the cutting fluid, which can alter the properties of the cutting fluid. In scientific literature there is no information on the effect of the hydraulic oil entering the cutting fluid on the tool life and roughness. In this regard, at the laboratory of the Department of Machining and Assembly of the Technical University of Liberec, there has been conducted a study to ascertain the effects of hydraulic oil getting into different types of cutting fluids during the milling of stainless steel.

Equal-channel angular pressing is a method of severe plastic deformation, which implies high deformation into the material and leads to grain size reduction and strength increase. It was applied on a twin-roll cast Al-Mg-Sc alloy, which contained Al3(Sc,Zr) particles formed during annealing at 300 °C for 8 hours. The evolution of the microstructure and mechanical properties after deformation was studied during isochronal heating 50 K/50 min. Strengthening occurred during annealing at lower temperatures and was followed by prominent microhardness drop, which was connected with formation of new grains and recrystallization. The presence of Al3(Sc,Zr) particles in the matrix is accounted for the high temperature stability.

This paper describes a modelling methodology that predicts a contour of a pneumatic tyre in the curing mould. Tyre contour is designed to be in the equilibrium shape. Such shape is described by a system of complex mathematical equations that has to be solved numerically. In this new approach a standard FEM software is employed to gain the shape without the need of dealing with these equations manually. The quality of the proposal of FEM approach was assessed by comparing the meridian to a verified solution for several tyre constructions and sizes. Selected results are presented to show the accuracy of the FE modelling procedure. Nowadays, most of the produced tyres are of a radial construction. Therefore, this paper deals only with radial tyres.