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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.

An application of an adhesive bonding technology is limited by cyclic loading of an adhesive bond. The aim of the experiment is to clarify a fatigue behaviour (low-cyclic tests of the fatigue) of four structural two-component epoxy adhesives applied to an alloy AlCu4Mg. The aim of the research was to evaluate a service life of the adhesive bond in terms of its fatigue stressing at the quasi static shear test. From that reason values of a passing loading for low-cyclic fatigue test were chosen for tested adhesives, i.e. 25 %, 50 % and 75 % from a reference value of a maximum force gained at the static test according to CSN EN 1465. The critical value at the low-cyclic fatigue test was determined from the experiment results for the adhesive bond as 75 %. Most of the adhesive bonds did not reach 100 cycles at this value.
It is obvious from the results that the considerable change of the adhesive bond strength did not occur after 100 cycles at the passing loading corresponding to 25 % and 50 % of the average maximum strength of the adhesive bond. The average fall of the resultant adhesive bond strength was in the interval 3 % to 11 %.

An adhesive bonding technology is limited by a cyclic loading of an adhesive bond. The paper deals with a testing of a low-cyclic fatigue of single-lap bonds reinforced with glass beads (B159, a fraction size 90 ± 20 μm). The aim of the research is a study of a low-cyclic behaviour of structural adhesive bonds by means of a scanning electron microscopy (SEM). The research will contribute to a clarification of the fatigue behaviour (low-cyclic) of structural adhesive bonds. The aim of the study was to evaluate a service life of the adhesive bond in terms of its fatigue loading at a low-cyclic shear test. Values of a pulsating loading for the low-cyclic fatigue tests were chosen from this reason for tested adhesives from static tensile test determined a reference value of a maximum force gained at a statical test according to the standard CSN EN 1465. The number of cycles was 1000 at the 30 % strength reached at the static tensile test of the adhesive itself. The cumulative effect of the shear cyclic loading after 1000 cycles showed micro- and nanocracks in the area of the adhesive. The experiment results did not confirm the assumption that repeated cyclic loading could lead to the premature failure of the adhesive bond.

Experiments and numerical simulations were conducted to analyze the deformation zone of aluminum cable in the conform extrusion process, and complex metal flow is observed by finite element. In this report, detailed studies were especially focused on the width of the extruding dies mouth and leakage gap which influenced on the metal deformation, then the stress and strain distribution and contact force distribution of arbitrary step were obtained with respect to different technical parameters among random steps. Furthermore, the relationship between the parameters of Δh and W/H was given, indicating that the intense internal Shear Band-IISB and leak gap affect the metal forming behavior, and enlarge obviously plastic deformation zone in a certain range. Consequently, it's proper to be helpful for metal homogeneous deformation to reduce the entrance width of the extruding mold.

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 contribution contains results of bonded joints strength tests. The tests were carried out according to the modified standard CSN EN 1465 (66 8510). For bonding the spruce three-ply wood of 4 mm thickness was used (according to CSN EN 636). The test samples of 100 x 25 mm size were cut out from a semi-product of 2440 x 1220 mm size in the direction of its longer side (angle 0°), in the oblique direction (angle 45°) and in the direction of its shorter side (crosswise - angle 90°). The bonding was carried out using eight different domestic as well as foreign adhesives according to the technology prescribed by the producer. All used adhesives were designated for wood bonding. At the bonding the consumption of the adhesive was determined. After curing the bonded assemblies were loaded using a universal tensile-strength testing machine up to the rupture. The rupture force and the rupture type were registered. Finally the technical-economical evaluation of the experiments was carried out.

An article deals with a realization and a statistical evaluation of a pressure test using a hydraulic testing machine ZD 40 in order to determine a strength of a designed implant prototype of a femoral component, more precisely a maximal force F that breaks a material and creates a crack. It is needed to make real testing samples of the new implant prototype of the femoral component for this purpose. Four pieces of testing samples are made in cooperation with the company in Velka Bites. Because of a price and availability in a range of offered cast materials testing samples are made of a bio tolerated cobalt alloy Co-Cr-Mo that is frequently implanted to a live organism. The implant prototype of the femoral component is designed from evaluated CT data of a patient's affected knee-joint (a femur distal part, a proximal tibia part). An individual 3D model of the implant prototype of the femoral component is created on the basis of editing of gained data in software CATIA.
The created 3D model is converted to *.stl format with a high resolution. Subsequently, the shell implant of the femoral component (a master model) is made using an additive method FDM (Fused Deposition Modelling). The next production method follows - production of a ceramic mould and casting of the real implant prototype of the femoral component from the bio tolerated cobalt alloy Co-Cr-Mo.

Hot tears represents serious defects, which are in most cases considered as unacceptable and may even result in disposal of final casting. The cause hot tear initiation is mainly a combination of several mechanisms (incorrect mold construction, chemical composition of used alloy, purity of used alloy, casting process conditions etc.). Basic principles of hot tears initialization can be considered relatively clarified, but a comprehensive and coherent view is still missing. The goal of proposed project was to design a coherent system to analyze emerging hot tears in the aluminum castings. The proposed mechanism is based on a number of concepts - a combination of "dog bone" and "T-section" tests. During the experiments will be possible to record the temperature at critical points, a tensile force in shrinking casting and by using heat-resistant glass placed above the heat node will be possible to directly observe the tears. Initial experiments will focus on verifying the functionality of the apparatus, the aim will be to analyze the impact of the solidification interval on hot tears.

Lead is traditionally used for completing free-machining materials. This paper deals with newly developed lead free copper alloys. Unfortunately, lead affects the haematological and nervous system. Therefore, materials containing lead represent one of the greatest environmental problems in world production. Research Material Institute in Panenske Brezany (CZ) developed new environmentally friendly cooper alloys. Machinability of these materials was tested at the Department of Machining, Process Planning and Metrology CTU in Prague. Some of the research results related to the machinability from the viewpoint of chip forms, surface roughness, cutting temperature, cutting time in drilling with constant feed force, and forces in cutting are presented.

The article deals with experimental measurements of force effects that direct blow develops taekwondo sportsman. Power effects are captured using a high speed camera. Experimental measurements have confirmed the results of many scientific papers that deal with the measurement of the force effects of combat sports athletes, etc. There are described some methods that are used in medicine and biomechanics to view internal organs or injury detection.

Contribution is focused on the analysis of power ratios on a drive shaft of a single-stage front gearbox and comparison of design solution of drive shaft using selected materials suitable for shaft production in terms of minimizing gearbox dimensions with respect to maintaining the transmitted power. The aim of the authors is to achieve the smallest possible dimensions of the gearbox shaft by changing the materials from which it is made.

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.

Additive manufacturing (AM) allows printing from different materials: from wax to plastic and even metal. This paper concentrates on Direct Metal Laser Sintering (DMLS), which allows printing to create complex parts from different kinds of metal. Inconel 718 was chosen for this research. This material is used especially in the aerospace industry and in other demanding applications due to its characteristic properties, which include high strength at high temperatures, corrosion resistance, low thermal conductivity, high hardness, work hardening and low thermal conductivity. Components used in aeroplanes must be very reliable, lightweight and their mechanical stresses must be accurately described, because the components are designed with respect to these criteria. For this reason, each material must be perfectly described in terms of mechanical properties and their minimum limits must be identified. Tensile testing is the best way to find the basic set of mechanical properties of a material. The samples were printed in two different orientations on a building platform and the differences in mechanical properties were investigated. The effect of machining on mechanical properties was also investigated.

The microstructure, phase constitution and hardness of Cr-V ledeburitic tool steel Vanadis 6 subjected to sub-zero treatment at -140 °C and for different soaking times have been investigated. The microstructures have been characterized using the light microscopy, scanning electron microscopy and X-ray diffraction. The metallurgical aspects include the reduction of the retained austenite amount and increase in carbide count, as compared to conventionally heat treated material. The matrix is martensitic with certain amount of retained austenite, irrespectively to the time of sub-zero treatment. The amount of retained austenite has been significantly decreased from 20.2 vol. % to minimum 3.2 vol. % at 48 h soaking time. The microstructure of sub-zero treated steel contains eutectic, secondary and increased count of small globular carbides. The count of small globular carbides for conventionally heat treated samples was around 48 x 103 / mm2 and for sub-zero treated samples was increased more than four times with maximum 209 x 103 / mm2 at 24 h soaking time. These particles have size of up 500 nm but 100 nm in most cases. The hardness has been increased as compared to no sub-zero treated samples from 875 ± 16 HV 10 up to 954.6 ± 14 HV 10 at holding time 48 h.

The rolling process is widely used to manufacture high-performance splined shaft components. However, there is a convex at root on free end of spline formed by rolling with round dies. However, the analysis and representation of this forming problem are difficulty due to the complexity of motion and multiplicity of processing parameters. This paper concentrates on the corner filling problem, and a physical analog experiment was designed to investigate the problem. The physical experimental results indicated that the designed experiment can reflect the formation of convex during spline rolling process. The finite element analysis of the physical analog experiment process was carried out to study the influences of friction condition and end shape of billet on convex at root of rolled spline. The results indicated that the height of convex will be reduced with increasing friction condition; the height of convex can be reduced by optimizing the end shape of billet. The results of present study provide a basis for optimizing and controlling the forming quality on free end during spline rolling process.

This paper deals with the preparation, composition and mechanical resistance of inorganic-organic nanolayers with built-in hydrophobic groups through sol-gel synthesis. The components of the nanolayers are 3-(trimethoxysilyl)propyl methacrylate, tetraethyl orthosilicate and hydrophobic chains - hydrocarbon chains in the range of 8 to 16 carbons. The study is aimed at evaluating the mechanical properties of prepared nanolayers with different hydrophobic chains compared to a reference sample without any hydrophobic groups. An abrasion resistance test was performed on several selected nanolayers with the best hydrophobic and antifouling properties. In the framework of the research, nanolayers prepared with polymerization achieved by heating at 85 °C or 150 °C were compared. The best mechanical properties and hydrophobicity of prepared nanolayers was AF12 with a hexadecyl hydrocarbon chain polymerized at 150 °C. These nanolayers are suitable for marine, underwater or any other hydrophobic application results from performed research.

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.

An intensive abrasive wear of agricultural machines and their parts occurs at the soil processing. An undesirable change of a tool surface occurs owing to the wear. Namely ploughshares of a plough are intensively abrasive worn. This undesirable change leads to a function loss. The paper deals with an evaluation of the ploughshare service life. The aim of the research was to evaluate the wear of the ploughshare with a layer of a carbide hardfacing OK Tubrodur 15.82 deposited on a bottom side of the ploughshare. The research was performed within a laboratory testing (a hardness HV30 and a wear) and field tests. Laboratory experiment results proved that the overlay material showed a significant increase of the wear resistance and the hardness. These conclusions of the laboratory testing were certified at the field tests. The research results certified this procedure as an efficient solution at the decreasing of the ploughshare wear at the ploughing.

Plasma technology of deposition of thin layers is currently the commonly used technology serving to influence the surface properties of various materials (metals, polymers, ceramics, etc.). The great advantage of applied thin layers is that although they can significantly change the surface properties of coated materials, their advantageous volumetric properties are preserved. The experimental part of work describes the evaluation of the properties of duplex system of the plasma nitrided layer with DLC coating and confronts them with the properties of plasma nitrided layers and polished surfaces. 42CrMo4 and 17Ni4CrMo steels were chosen for experiment. Experimental part deals with the practical analysis of the determination of tribological properties of thin film-substrate (specifically nitrided layer-DLC coating). The tribological properties of selected steels were evaluated using the "Pin on Disc" method. Modified layer formed by duplex system PN+DLC showed up to 8x lower coefficient of friction than nitrided or only polished surface.

This article deals with the experimental grinding of cemented carbide cutting tools. Several carbide milling tools with the same geometry were ground under the different grinding conditions and strategy described in this research. The main aim is to determine the influence of the grinding process on the quality of the cutting edge. Different grinding conditions and strategies were used in grinding of the primary radial relief on the peripheral cutting edge. The cutting edge was analysed after grinding by an optical-scanning device and an electron microscope to determine the quality of the cutting edge and radial relief face of the tool. EDX analysis was used for the chemical characterization of the ground surface. The chipping of the cutting edge occurred when the grinding feed rate and the wheel spin direction was changed. The influence of the grinding conditions and strategy on the chipping formation was determined. The mean radius of the cutting edge after grinding was also measured. The results of this work will be used for further research and cutting experiments.

The article deals with hardness tests and dimensional and shape precision analysis of construction and agricultural machinery components, namely with the clamping head and case of hydraulic hammer. The clamping head is made of 41 4220 class (1.7131, 16MnCr5) construction stainless steel and the case is made of 41 5130 class (1.7218, 25CrMo4) construction stainless steel. The micro hardness was measured on VICKERS LM 700 AT hardness tester, according to the national standard STN EN ISO 6507-1: this procedure includes injection of a diamond regular four-bladed pyramid with a 136° peak angle into the tested material with following parameters: objective lens X50, load 10 N, indentation time 10 s. The average HV micro hardness value was determined from 10 measuring points (distances) on 70 samples of the hydraulic hammer case and from 10 measuring points (distances) on 200 samples of the hydraulic hammer clamping head. To measure dimensional and shape accuracy, Perthometer MAHR, equipped with PCV 350 slider unit with sensors with 350 mm length range and a mobile 6-axis 3D measuring arm Romer Absolute Arm 7535 with a working range of 3.5 m were used. This way, basic contour elements were determined: radii, distances and angles. Using the mobile 3D measuring arm, the tolerances of circularity, coaxiallity and perpendicularity were also measured. Technical drawings, contourrograph measuring protocols and tables of dimensional and shape precision deviations are listed in the conclusion of the article.

Coating of the tools for metal machining has been used for a long time, application of the coating to wood machining tools is not so explored. The aim of research in this area is to expand the possibilities of the using of PVD coatings in untraditional field at wood wool production in company, that thermo isolation and sound isolation plates manufactures. In the production of wood fibers by technology like planning, during the work the cutting edge of the knife is worn-down and the resulting product loses quality. Often grinding is required, knife dimensions are changed and lose its functional surface. The article is focused on the choose of the coating type on the base of input analysis of the tool material. Analysis is aimed to detection of the chemical content of elements, evaluation of the microstructure and mechanical properties. On the basis of the results, we proposed the type of coating applied to the sample and the tool. Coated sample was evaluated in terms of coating properties namely the thickness, tribological properties, chemical composition (EDX analysis) and microhardness. After the experiment, we have evaluated the state of cutting edge and compared it with the uncoated tool. The positive effect of the coating on the change of the cutting properties of the knife and the quality of the wood wool have been recorded.

This paper deals with numerical simulations and with experimental testing of chassis of low-floor trams. This chassis was designed with respect to low-floor construction, low weight, good driveability of a tram and with respect to fulfillment of standards and regulations. The chassis is in a numerical simulation burdened by load conditions according to EN 13749:2011 even during an experimental testing. The simulation is performed using the FEM Nastran solver implemented in the CAD system Siemens NX 11. Based on FEA the locations for strain gauges during testing were found. A total number of 40 strain gauges were used to measure the strain which was then recalculated to uniaxial stress. The testing was performed on hydraulic test bench Inova. The results of FEA and of an experimental testing were compared.

This paper deals with influence of tool wear on surface integrity after turning of stainless steels. Surface integrity is expressed in terms of structure transformation initiated by turning process as well as Barkhausen noise emission. Furthermore, components of cutting forces are also measured as a function of tool wear and their evolution along with developed flank wear VB is presented. The results indicate that presence of carbides in the matrix - their size and density play a significant role in the resistance of the matrix against the structure transformations. The results also indicate that Barkhausen noise technique is sensitive to structure transformations of austenite steels initiated by turning process.

A high performance of heat transfer fluid has a great influence on the size, weight and cost of heat transfer systems, therefore a high-performance heat transfer fluid is very important in many industries. Over the last decades nanofluids have been developed. According to many researchers and publications on nanofluids its evident that nanofluids are found to exhibit enhance thermal conductivity. The aim of this experiment was to investigate the change of workpiece temperature during drilling using Jatropha oil with nanoparticle and water with iron nanoparticle as lubricating and cooling fluids. These experiments were carried out with samples of nanofluid with different volume ratio. Samples JN1, JN5 and JN10 of iron nanoparticles in the base Jatropha oil with iron volume fraction 1%, 5% and 10% respectively. Samples WN1, WN5 and WN10 of iron nanoparticles in the base water with iron volume fraction 1%, 5% and 10% respectively. The work arises from the projects which were realized at University J. E. Purkyně, Faculty of Mechanical Engineering, in cooperation with Namibia University of Science and technology, department of Mechanical Engineering.

The process of developing new universal cutting fluids is labor-intensive due to the requirement of conducting experiments to determine the impact of numerous additives on tool life during different technological operations. Therefore, finding the best cutting fluid, the use of which will result in the longest tool life, is a long and laborious process. To reduce labor intensity while creating new cutting fluids accelerated methods are applied first, such as the method of determining the tribometric properties of a new fluid. Subsequently wear tests are carried out, using only those cutting fluids which show the best tribological behavior.
The aim of this study is to reduce labor intensity in developing new universal cutting fluids. For this purpose, a new accelerated method has been developed, which helps to determine the capability of the fluid to counteract the adhesion between the chips and the cutting tool. Furthermore, a new sequence of cutting fluid tests has been proposed which significantly reduces the amount of wear tests, resulting inconsiderable reduction of the overall labor intensity in the development of new cutting fluids.

Polymer composite honeycomb sandwich panels (PCHSPs) are used in many sectors of industry, such as in aerospace, defense and public transport factory. Sandwich panels consist of two facing skins and the core. Products of all industry sectors have to meet requirements on their dependability. This research paper deals with a proposal of the most appropriate methodology for dependability testing of PCHSPs products used in transport industry. Dependability is a global concept that includes terms such as availability, reliability, durability, maintainability, supportability, etc. The experiments have shown S-N curves with damages and without damages of PCHSPs. An important part of dependability is to be fonded the limit states of the studied object, which are for PCHSPs are characterized by fiber cracking and (core) delamination. Dependability evaluation consists of analysis and tests. For every test, it is necessary to be developed its test plan. Facing skin components of the sandwich panels may particularly be damaged. There are several methods of non-destructive testing, which can be used to determine the damage of facing skins of sandwich panels. Infrared thermography (IRNDT) is one of them. IRNDT utilizes thermo-physical properties of the materials, including thermal diffusivity.

The abrasive wear of pulley surfaces at winding of the ropes causes changes of the shape and quality surface of the groove and has influenced lifetime of the skidding machine. The pulley is made of steel C45E without heat treatment and its structure is not suitable for the abrasive wear of the pair metal-metal. Contribution describes a research aimed to changes in material structure by the heat treatment. The pulleys (first one in original state and second one after heat treatment) were tested in operating load at skidding during 320 hours. After experimental test, measurable properties as weight loss, groove dimensions of the pulleys were compared. On the samples from the pulleys, material resistence to wear was tested too. Another alternative for change of material properties would be an aplication of various types of weld deposits on the steel C45E. We have examined the quality of weld deposits and compared their hardness and microstructure. The results of experimental tests resulted to recommendations for practice.

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.

One of the basic principles of railway vehicles is their carrying and guiding. In the contact pair of a wheel and a rail, one body is rolled on the surface of the other part and all main forces are transmitted in this contact. Contact between wheel and rail is also important from an economic aspect as it is related to the wear of the track rails and the wheel thread itself, including the wheel flange, and has caused the necessary maintenance of the track and the vehicles themselves. Therefore, our article focuses on simulating the influence of a flat wheel on changes in wheel forces. The model was created in the CATIA program and was consequently imported into the SIMPACK program, which was followed by analysis of the passage of the vehicle along the track. In the simulation, we considered an ideal track and a wheel flat on the right front wheel. We also plan to work with these results by adding and comparing them with results obtained by applying irregularity to our ideal track.