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This paper deals with the causes of failure of total hip replacement. Hip joint replacement is one of the most frequently used surgical procedures worldwide. More than 200,000 surgeries are performed only in Europe each year, following early attempts by John Charnley. Currently, more than 340 of the total 4431 implants per year are reoperated in Slovakia. Despite the excellent properties of the titanium alloy, endoprosthesis often fails and the hip replacement is necessary. Common causes are overloading and cracking, static or dynamic. Other causes of failure include injury, implantation failure, manufacturing inaccuracies, and non-compliance with the manufacturing process.

Al-Cu-Mg based alloys are often used in the automotive industry. There are characterized by high strength characteristics but poor corrosion resistance, which appears to be problematic in this sector. The manufactured blanks of these alloys may be protected by some of the barrier protection methods, including cladding. Semi-finished products made of these methods can be protected against corrosion by a thin layer of aluminium oxides - called clad Durals. The surface layer creates a stable and durable Al2O3 layer, which provides corrosion resistance, which leads to an extended service life of the piece.
However, this type of protection is adversely affected by the effect of copper diffusion, which is dependent on the heat treatment mode of the alloy. Temperature and temperature hold are the main factors influencing the diffusion process. In the solution annealing of aluminium alloys, the temperature is in the range of (470-500) ° C, resulting in intense diffusion processes at the inter phases interfacial.
The paper deals with the analysis of the influence of the heat treatment regime on the corrosion resistance of Al2024 alloy sheets (AlCu4Mg1 type alloy) provided with an Al1050 alloy clad coating on both sides in a corrosive salt mist environment in accordance with EN ISO 9227, which is supposed to have a positive effect on extending the service life of a car component.

An important trend today is the continual improvement of product quality with the objective of increased customer satisfaction, but also leading to more effective cost reduction management. Effective quality management in a company also enables increasing production productivity thanks to the increasing amount of top-quality products made and the consequent minimalization of repairs of non-conforming workpieces. This contribution deals with one of the important tools for ensuring quality in the production process using the FMEA (Failure Mode and Effect Analysis) method used in the production of roller bearings for the automobile industry.

This paper presents some advanced techniques on CAD modelling and CAM programming for 5-axis machining of free-form surfaces. In the CAD stage, based on surface partitioning, the design surface can be created with separate regions such as convex, concave and saddle. Point-based techniques are used to create the original surface and the boundary curves of the regions. Some other CAD/CAM techniques for determining tool sizes and tool orientations are also proposed to generate gouge-free tool paths for each region. A simple B-spline surface was given as an example to demonstrate the proposed techniques implemented in Creo Parametric. The points on the design surface and on the boundaries were generated by a Matlab program developed by the author.

The paper describes the utilisation of several physical diagrams for the modelling of chosen electric car charging in alternative simulation software for an electric power system. The description and evaluation of possible ways for modelling of electric vehicle charging with the results that are sutable for basic energetic analysis are performed, and for all cases given models are used in chosen simulation circuits. Modelling of electric vehicle charging becomes important with the increasing trend of used electric cars and installed charging stations. Electric vehicle charging represents the rising amount of loads with nonstandard behaviour which has been connected to the distribution power grid. The behaviour of electric cars during charging is not the same as a standard passive load, which can be defined by consumed active power for a specified period of time. The charging process has a specific behaviour, which is derived by the type of a charging station and communication with the battery in the car. While charging the distribution grid is influenced. The undesirable occurred phenomena are unbalanced powers and generation of harmonics, which can cause voltage and current asymmetry in the grid and subsequently worsen electrical voltage quality. Furthermore, the load capacity of distribution lines is reduced and therefore the steep increase of loading limits their safety and economic usage.

This paper deals with basic methodology of surface evaluation of functional surfaces, which were prepared by various machining methods (turning, milling and grinding). Here are the basic 2D (profile) parameters and 3D (spatial) parameters and their properties in relation to the machined surface. Parameters of machined surfaces were obtained by CCI Lite Coherence Correlation Interferometer from Taylor Hobson and evaluated using the TalyMap Platinum software. The article further demonstrates the inappropriateness of the surface structure assessment with only the parameter Ra (mean arithmetic deviation of the profile), which is the most common method in technical practice. This methodology extends the possibilities of a comprehensive assessment of exposed surfaces of machine parts.

Topological optimization is the process of reducing part weight while respecting strength requirements. This paper focuses on its possible positive consequences for the machining process. The main aim is to carry out a survey to obtain knowledge that will be applied during the topological optimization of a milling tool. According to all the indicators, the efficient implementation of lattice structures into the milling concept has the potential to achieve a high level of innovation, since the functional weight reduction of the tool allows for higher dynamics of the cutting process. The modified rigidity of the milling cutter and vibration absorption can extend the life of the cutting edge, and such a milling tool would provide a competitive advantage on the tool market.

Additive technologies are a dynamically evolving category of manufacturing methods for a wide range of industries, particularly engineering and related fields. Compared to traditional technologies based on chip machining, molding and casting, they offer new production options, particularly for complex shape components. At the same time, however, there are differences and limits that must be taken into account when designing functional machine parts. The important quality parameters of the products are in particular the dimensions and the quality of the surface. These factors are of fundamental importance for the subsequent assembly and function of a component in a plant assembly. They determine, together with the structural material properties, the usability of the component and the economic efficiency of the production in order to achieve the finished product with the minimum need for postprocessing the finished part. The submited text presents the results of the quality parameter research carried out on 3D print products made by the DMLS method, where the focus is put on the assessment of linear dimensions and the surface quality of samples from three selected materials and a combination of two print modifications. The measurement results are compared to generally valid standards and tabulated values to verify and eventually modify table values for use when designing a design solution with the use of 3D print products.

This work aimed to characterise microstructure and mechanical properties of polymer composite samples. The main task was to adapt the well-known techniques of metallography (i.e. sample preparation and microscopic examination) to documentation of multi-component polymer materials and to optimize the methods of light and electron microscopy for this particular purpose. There were several issues (e.g. low melting point, absence of electrical conductivity), which made the process different from metal samples preparation and observation and which needed to be addressed. Various mounting resins were tested for the samples to find the suitable one, then the process of grinding and polishing was optimized and finally the microstructure was documented using light and scanning electron microscopy (SEM). Samples in the undeformed state were examined as well as the samples subjected to tensile test at different temperatures. Prior to the microscopic observations the material was analysed using methods of thermal analysis (TG A, DSC) and infrared spectroscopy (FT-IR). The tensile tests were employed not only to determine the mechanical properties but also to obtain deformed samples for further microscopic observation.

The goal of the proposed methodology is to manage and evaluate investments across the portfolio of projects in the company, with extra focus on selecting engineering projects into the portfolio. In order to design an objective methodology, several analyses were conducted to verify a general validity of the methodology. The starting point is using methods which allow a high degree of flexibility in solving problems. The ANP method is suitable for the determination of priorities in network systems with different types of dependencies between the elements of the system. The DEMATEL method is used in this methodology to formulate the structure of relationships between the criteria of the system and obtain the criteria importance in the system. All calculations were carried out using the MAXIMA and Super Decisions software. The proposed methodology has been verified on a case study using real-life data supplied by the participating company. There were used methods of decision making, especially methods of operations research, linear programming and team expert selection methods.

An application of external fixator is a surgical method for the treatment of large bones fractures. This method has been proposed already a century ago, but despite the extensive development of science and technology, the fixator is often used in the original state of the proposal. [1] Therefore the patient and surgeons are dissatisfied with high weight and poor mobility of fixator during surgery and healing process. [2] Due to this fact it is necessary to apply new 3D technologies into this field of orthopedics and thus improve the current state of this tool. [3] In an account of this information, the 3D model of a new composite external fixator was created. In the research, the composite fixator was analyzed by the finite element method (FEM). Based on the results of FEM and the surgeon's requirements, the composite fixator was further improved and the final results show that the composite fixator proposed by the FEM is able to transfer the applied load from a patient. Therefore the data indicates that the implementation of composite material will further improve patients comfort, the healing process and the precision of surgery. Based on this fact, the mold has already been manufactured and the process of completing the product has started.

Previous work has proposed a process for implementing a lattice structure into a milling cutter body based on clustering in the milling cutter with modified main dimensions of a BCC cubic lattice structure cell. A finite element analysis model has been created to predict the strain and deformation in the struts of the lattice. The prediction made according to static loads demonstrates that the concept of a lightweight cutter meets the strength requirements, though its stiffness does not reach the fully-filled version. The methodologies for creating the FE model are described in this paper. HyperWorks with OptiStruct were used for these analyses. Local stiffness could be improved by varying the strut diameter or using a different type of basic cell for the lattice structure in problematic locations, especially in the area of the connection between the shell of the cutter and the lattice structures.

Nowadays there is a high trend and effort to find a suitable biodegradable metal, whose mechanical properties would be the same or higher to those of currently used biomaterials. Current biomaterials, such as stainless steels, cobalt-chromium alloys, and titanium alloys have superior mechanical properties, machinability, and durability, but are considered nondegradable, and long-term clinical complications may occur. Their biggest disadvantage is that the patient must have undergone a second removal surgery. Therefore, new biodegradable materials have been developed to eliminate the shortcomings of current biomaterials. Magnesium (Mg), iron (Fe) and zinc (Zn) based alloys have been proposed as biodegradable metals for medical application. Iron-based alloys show good mechanical properties compared to magnesium-based alloys. However, both of them exhibit bad corrosion properties, because the degradation rate of magnesium has proven to be high. On the other hand, the degradation of iron-based alloys is too slow in a physiological environment. The corrosion attack of both materials is not typically uniform. Therefore, zinc is proven to be a promising material for this application.

This article deals with state-of-art in the field of handling machines intended for disabled people, which serve for disabled entry of such people and for people with delimited locomotion. It contains calculation of forces, which act in the mechanical system of an electric device during its operation in real conditions, changes of reactions depending on the load and the climbing angle as this solved handling machine will designed for negotiation of staircases. The objective is the functional calculation of a driving mechanism of a stair chair marked SA Alfa, i. e. the calculation of loading forces and their action on the driving mechanism. It will serve in the next step as an input for the calculation of a required power under conditions of occurance of maximal resistance forces, which will be determining factor for dimensioning of driving components of this device.

Brass mechanical properties are not ideal, particularly when the brass is exposed to the effects of mechanical wear. Final finishing of functional surface of machine component is substantial for the particular choice of brass. The aim of the research was to approve or disapprove the hypothesis if abrasive - free ultrasonic finishing (bufo) of brass has higher wear resistance of surface compared to the classical machining. The results of the experiment showed that abrasive - free ultrasonic finishing (bufo) has a major impact on the size of the elliptical wear area. Surface finishing by classic machining formed on average a 41% larger elliptical wear area compared to surface with abrasive - free ultrasonic finishing. The hypothesis of experiment were verified and it is possible to consider that abrasive - free ultrasonic finishing (bufo) has considerable influence on wear resistance of the surface of machine parts.

The paper is part of the publication series, which describe the most significant and innovative research and development design solutions and computational procedures as part of European structural funds project. The object of this article is strength conditions assessment of a new structure of railway tank wagon. For validation of the new construction assemblies, there has been created a substitute simulation model. Results of calculations and prototype tests prove, that new structure of the construction satisfies strength assessments according to valid requirements and standards.

The aim of the work was to evaluate the whole system of the springs of a passenger car. The influence of inflation and the type of tires on the acceleration of the various parts of the car (axle, steering wheel, driver's seat attachment, body shell and acceleration affecting the driver) was investigated. The types of shock absorbers and springs of the passenger car were also examined. The sensors used acceleration and pressure sensors between the wheel and the road using test stands. The benefits and reserves of the individual systems were compared, and in the systems with the cushioning rigidity, all the suspension setups were evaluated. The work was done experimentally in laboratory environment as well as in real operation.

Lattice structures are one way to reduce the weight of a component while respecting its strength requirements. These structures are based on cubic cells, therefore, they are not fully applicable to rotating parts which should be lightweight. This article particularly addresses this issue. A solution is sought for how to adapt lattice structures for a milling cutter. The final redesign of the topology allows a continuous flow of generated stress into the whole body of the cutter. Further, the solid part of the milling cutter is modified for Metal Additive Manufacturing (MAM) and the functionality of the optimised cutter is verified by Finite Element Analysis (FEA). The results of the analysis are compared with a conventional cutter with the same outer shell. The findings from the static analysis indicate that the milling cutter can be considered to be competitive.

The article describes usage of the CRAFT method and its influence on the optimization of flow logistics. The method helps to reduce the cost of basic material flow determination in production, assembly of production units, material handling, storage of individual parts and the transport of finished products. By using the method, long traffic routes, unproductive times and warehouse inventory that unnecessarily increase our costs were removed. In today's competitive environment, it is necessary to improve continuously all processes not only in production, and this method enables us to effectively achieve defined business goals.

Aiming to study the working efficiency and stability of the loader, the hydraulic system of the loader is studied. Taking the ZL50 loader as the research carrier, the working conditions of the loader and the working principle of the hydraulic system are analysed at first. AEMSim software is used to simulate and analyse the hy-draulic system, and the necessity of using the algorithm to optimize the hydraulic system is put forward. Secondly, the mathematical model of key hydraulic system optimization is deduced, and genetic algorithm and neural net-work algorithm are used to optimize the analysis of the objective function, and the simulation results are compared and analysed again. The results show that the parameters optimized by GA and BP algorithm are better than the original parameters. Further analysis shows that the parameters optimized by GA algorithm are better than BP algorithm in smoothness.

Aluminium extraction and production is energy intensive and have a relatively large environmental impact. One of the steps in the production of sheet aluminium is the cooling of the rolled metal after the hot mill. This study introduces an option to replace the active cooling by an environmental friendly method and eliminate the otherwise necessary logistic step of relocating the coils after cooling. This was done by developing a thermal model of the coils, calculating, based on the model, the required airflow and verifying it with test series. The experimental setup is in a high-bay storage facility belonging to a aluminium production line. The results of the test series show the differences between simulations and real life settings.

Titanium is considered to be the metal of the 21st century . A material which has small density (at least two-three times smaller than iron), plasticity, shapeability, high resistance, rigidity and longevity has been required for a long time. It is required not to loose those features at high temperatures, be non-degradable in air, river and sea water, not to be soluble in acides and lyes; at the same time, it requires to have sufficient amount in terrestrial crust. Titanium is such a material. Due to its specific qualities, its applications have been spreading into many areas such as medicine (implants), space (material for space technology), chemical facilities, ships for marine transport (resistance to acids and salts), wall hooks for climbers (low density and high rigidity), ... However, titanium mechanical features lead to new problems during its technological machining. It is necessary to apply considerably different approach in its cutting. During cutting, titanium and its alloys behave specifically and it is important to know this behaviour and use it for effective part production.

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.

AISI 304 stainless steel is widely used in many industries due to its good properties such as corrosion resistance and mechanical properties. However, this steel is usually exposed to a severe environment that leads to high corrosion and mechanical failure. This study aims to examine the corrosion behavior of spin-coated AISI 304 stainless steel in a simulated marine environment contains 3.5 wt. % NaCl, by preparing and characterizing nanocomposite coatings with different weight fractions of TiO 2 (0, 1, 2, 3 wt. %) dispersed in a gelatin matrix. Three spinning speed sets (Low (L): 250-1000, Medium (M): 500-2500 and High (H): 750-4000) rpm were chosen to inspect the effect of spinning speed on the characteristics of coatings. Nanoparticles dispersed in gelatin matrix were examined by XRD, SEM, and EDX. The results approved the formation of crack-free and homogeneous coatings without any noticeable defect. Moreover, the corrosion evaluations were measured by potentiodynamic polarization technique. The results showed that compared to uncoated AISI 304 steel, the corrosion behavior of TiO 2 nanoparticles dispersed in gelatin matrix considerably improved the uniform and localized corrosion. The corrosion test results showed that increasing the spinning speed to a certain limit has a positive impact on the corrosion characteristics.

The efficient processing of materials, the development of machine concepts and grinding tools, as well as growing environmental and economic pressure are existing challenges in grinding. Chromium coatings are mainly used for components where corrosion protection is required, but also for the repair of worn parts. This paper presents and discusses the possibilities of utilizing changes in feed rate to achieve guaranteed surface integrity, which is very important for the life of the component. The results are presented in the form of tables and graphs, where I focus mainly on parameters of surface roughness and circularity.

A constantly growing competition in world economy results in an increasing demand for solutions enhancing both the effiiency of enterprises and the quality of goods produced. A solution which meets both requirements is robotization of production processes, i. e. replacing human labour with the work of industrial robots on the positions where tasks are monotonous, onerous or dangerous. The paper presents the economic analysis of the use of robots in production processes, as well as its technological conditioning. On the example of robotization of processes in the enterprise producing semi-trailers, the method of calculating the re-turn on investment was presented and an analysis of the labor costs of the worker and the robot at a given workplace was made.

Using innovative methods of heat treatment (HT) for high-strength steels, such as the Q&P process, very favourable ratios of ductility and strength can be achieved. Materials processed by this technology have higher content of retained austenite, and therefore better ductility. This experiment deals with HT of 42SiCr steel. The conventional HT and the Q&P processing are compared with respect to material properties. Metallographic analysis, hardness measurement, X-ray diffraction phase analysis (of retained austenite content) and tensile testing were performed. For the hardened samples, the effects of the cooling rate on their microstructure were assessed and the measured real-world data were compared with the simulations performed in the FEA simulation software DEFORMTM based on the thermocouple records. After a conventional HT, the material showed little sensitivity to the cooling rate. In contrast, the Q&P process with higher quenching temperatures resulted in a higher austenite content and elongation of up to 15 % at a strength of 1800 MPa.

Automatic workpiece exchange is one of the important parts of every flexible manufacturing system. This part largely allows complete automation of the component's production cycle. It also greatly contributes to a significant reduction in the workpiece clamping times and contribute to a reduction in the downtime during the machining process. It also allows eliminating a human factor from the production process, thereby contributing to greater machine utilization and higher machining productivity. This article describes certain modifications of interchangeable pallet system designated for specific training CNC machine tool EMCO Concept Mill 105 situated in the laboratory at the Department of Automation and Production Systems. This machine has considerably limited workspace and length of feeds which are the most limiting parameters during design. Mentioned modifications allow manipulating with designed pallets with the industrial robot or special manipulator instead of previously designed manual handling.

In the presented work, static and dynamic properties of two, theoretically identical composite rods were studied. Those two kinds of rod were made of pre-impregnated fibers so called "prepregs". The first of them was made by means of wrapping technology, which is simply just helical layering of one wide tape around a rotating mandrel. The weakness of this method is possible using only for straight parts. That is why a simultaneous deposition of several thinner filaments in a form of tape called winding was used in order to optimize this technology also for curved parts with various cross-sections.
The target of this work was to compile numerical model and experimentally compare flexural strength of the theoretically identical wrapped and wound rods in the static three point test.Further small samples cut and extracted from those rods were subjected to dynamic bending loading on Dynamic Mechanical Analyzer, with various loading speed, in order to obtain also the dynamic properties. The found results and conclusions of this article should provide a basic idea how significantly the manufacturing process could affects the microstructure and real mechanical properties of long fibers composite parts.

This paper presents the theoretical calculations of the foaming process of selected powder foaming agents (TiH2, CaH2, MgH2, ZrH2, CaCO3 and MgCO3) regarding the volume of gas, relative density and density of the metal foam obtained with respect to the use of a certain amount of powdered blowing agent. This work is carried out in the frame of the university project in which a small subproject is dealing with the problem of the cellular lightweight metal structures. Furthermore by calculating the diffusion of hydrogen in both solid and liquid aluminium there were found results for the duration of the anticipated action of the powdered blowing agent (0.75, 1.0, 1.25, 1.50, 1.75 and 2.0 wt. %).