Three views on kinematic analysis of Whitworth mechanism of a shaping machine

Machines play a very important role in today's industry because they are the foundation of automation. An essential integral part of each machine is the mechanism. In many cases, there are several mechanisms working independently inside the machine or the movements of the individual mechanisms are joined. It is necessary to understand a mechanisms motion to be possible to set up its right working conditions and so also to achieve the most appropriate machine efficiency. The article deals with the kinematic analysis of a Whitworth mechanism. This mechanism is a part of a shaping machine that is used in real technical practice. Three approaches (analytical, graphical and solution with computer aid) to the specification of kinematics characteristics of a cutting tool motion are presented in the article. Also, the advantages and disadvantages of the presented approaches are briefly described in the paper. A comparison of results of kinematic analysis has shown that there are no differences in the achieved values; they are only in an accuracy that follows from the essence of individual approaches to the solution. © 2020 Int. J. Mech. Eng. Rob. Res

Investigation of toothed shaft from the view of modal parameters

The paper deals with the investigation of toothed shaft from the view of modal analysis, which is a base of dynamic analysis. The gear mechanism is newly designed based on new principle, at which the motion and power are transferred from one input shaft to two output shafts in one direction. Considering that structures vibrate in special shapes when excited at their resonant frequencies, by understanding the mode shapes, all the possible types of vibration can be predicted. The paper aimed to create experimental and computational model of the shaft with subsequent verification of selected theories, to compare results obtained by numerical and experimental modal analysis and to assess the dynamic characteristics of the component with respect to its operating conditions. There are described conditions of both numerical and experimental modal analysis in the paper. The measurements have shown that the values of natural frequencies along with the natural shapes are adequate and comparable within both of the investigation methods. Moreover, from the results it is clear that output shaft should not be subjected to resonance. On the other hand, by means of modal analysis, the number of teeth was specified, that can be risky at the dynamic load of the gear, if the gear ratio changes. © 2019, Strojarski Facultet. All rights reserved.Ministry of Education, Science, Research and Sport of Slovak Republic [KEGA 007TUKE-4/2018, VEGA 1/0795/19, APVV-17-0380

Study of the sound absorption properties of 3D-printed open-porous ABS material structures

Noise pollution is a negative factor that affects our environment. It is, therefore, necessary to take appropriate measures to minimize it. This article deals with the sound absorption properties of open-porous Acrylonitrile Butadiene Styrene (ABS) material structures that were produced using 3D printing technology. The material's ability to damp sound was evaluated based on the normal incidence sound absorption coefficient and the noise reduction coefficient, which were experimentally measured by the transfer function method using an acoustic impedance tube. The different factors that affect the sound absorption behavior of the studied ABS specimens are presented in this work. In this study, it was discovered that the sound absorption properties of the tested ABS samples are significantly influenced by many factors, namely by the type of 3D-printed, open-porous material structure, the excitation frequency, the sample thickness, and the air gap size behind the sound-absorbing materials inside the acoustic impedance tube. © 2020 by the authors.Ministry of Education, Science, Research, and Sport of the Slovak Republic [KEGA 007TUKE-4/2018, APVV-19-0550]; European Regional Development Fund in the Research Centre of Advanced Mechatronic Systems within the Operational Programme Research, Development, and Education [CZ.02.1.01/0.0/0.0/16_019/0000867

Effect of the weight reduction of a gear wheel on modal characteristics

The paper deals with the influence of gear weight reduction on its modal properties. The aim of the paper is to use the simulation tools to introduce the dependence of natural frequencies on the change in the shape of the gear, which is reflected in the change in weight. At the beginning of the paper, the theory and experimental bases of vibration testing and analysis are introduced to understand the principles of modal parameter specification. Verification of the boundary conditions used in the simulation was performed using the experimental method and it is described in the next part of the article. Tests confirmed the consistency of the values achieved by both approaches. Thus, the same boundary conditions could be used to specify the dependence of natural frequencies on the change in the geometry of the gear (which is associated with weight reduction). Numerical analysis was performed by FEM analysis using PTC Creo software. Experimental modal analysis was performed using a PULSE measurement system.Ministry of Education, Science, Research and Sport of SR [KEGA 007TUKE-4/2018, VEGA 1/0440/18

Tensile properties of four types of ABS lattice structures—A comparative study

This article aims to compare the behaviour of four types of lattice structures named Cartesian, Rhomboid, Octagonal, and Starlit under tensile stress loading. The structures were made of Acrylonitrile Butadiene Styrene (ABS) material using the Fused Filament Fabrication (FFF) technique with three different specific volumes (24, 42, and 60%). Five samples of each type were produced, and a total of 60 samples were tested. Experimental testing was performed according to EN ISO 527-1:2012 and EN ISO 527-2:2012. The obtained data were statistically processed, while no outliers were identified. The experimental results pointed out that the specimens' topology, together with the specific volume, very significantly affected the resultant ABS properties of the tested samples made of the same material. The comparative study showed that in terms of ultimate strength, yield strength, and Young's modulus, the Cartesian structure appeared to be the most suitable for tensile stress, and the least suitable structure was the Rhomboid structure. On the other hand, the Rhomboid-type of the structure showed not only the highest amount of absorbed energy but also the highest toughness among the investigated lattice structures, so in the near future, its behaviour under an impact test should be studied.Ministerstvo školstva, vedy, výskumu a športu Slovenskej republiky, (APVV-19-0550); Kultúrna a Edukacná Grantová Agentúra MŠVVaŠ SR, KEGA, (005TUKE-4/2021, 032TUKE-4/2022)The authors would like to thank the Ministry of Education, Science, Research, and Sport of the Slovak Republic for the direct support of this research through the projects APVV-19-0550, KEGA 005TUKE-4/2021 and KEGA 032TUKE-4/2022. [APVV-19-0550, KEGA 005TUKE-4/2021]; Ministry of Education, Science, Research, and Sport of the Slovak Republic [032TUKE-4/2022]; KEG

Thermal manifestations and nanoindentation of bone cements for orthopaedic surgery

Improving of bone cements properties is possible by research of variables influencing exothermal behaviour and mechanical properties. Paper deals with exothermal behaviour experimental evaluation of bone cements used for medical purposes. Specimens were prepared by a conventional manual mixing technique. The work addresses primary risk factor associated with application of bone cement to femoral canal. Different size samples of bone cement has been created with diameter d = 2; 5;12,5 mm fixed in dentacryl. As an experimental material, Palacos R+G high viscosity, radiopaque bone cement containing Gentamicin and Radiopaque bone cement Antibiotic Simplex with Tobramycin, was used. Thermal effect during exothermic polymerisation was measured with period I minute. Evaluated factors were mass and thickness of bone cement. Significant influence of bone cement mass on temperature has been found

Design of the levers at the development of new self-equalizing thrust bearings

Plain bearings are undoubtedly one of the main parts of the power machines (such as a turbine or compressor). However, there are many cases when in large power equipment is occurring asymmetrically loading on bearings due to thermal deformations, production inaccuracies, or simple deflection of the shaft. Presented research deals with the numerical analysis of levers being as the first step at the design of a new self-equalizing thrust bearing with the goal to find out its behaviour and base on that to make the improvements. The numerical analysis was done for the bearing with 12 segments using the software ANSYS. The boundary conditions were applied so to prevent the movement (collapse) of the system and at the same time use them to influence the stress distribution in the levers as little as possible. The steel 34CrNiMo6 has been used for the levers in a refined state. The achieved results confirmed the design of the levers, its sufficient stiffness, good functionality, and reliability. (C) 2021 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of ICSID 2020 Organizers.Ministry of Education, Science, Research and Sport of Slovak Republic [APVV-19-0550, KEGA 005TUKE-4/2021]Ministerstvo školstva, vedy, výskumu a športu Slovenskej republiky: APVV-19-0550; Kultúrna a Edukacná Grantová Agentúra MŠVVaŠ SR, KEGA: 005TUKE-4/202

Evaluation of the machinability of CW614N brass alloy

Brass alloys are widely used materials for general and industrial applications. However, the lead content in them forces manufacturers to develop new ecological types, the properties of which must be gradually specified in order for the product to be produced and processed more efficiently. The article deals with the evaluation of the machinability of CW614 brass by investigating the influence of technological parameters on the surface roughness of the machined surface and the intensity of vibrations during machining. The measured data were statistically processed; with the help of regression analysis, mathematical formulations of the influence of input parameters on monitored variables were defined and based on them, functional dependencies were plotted in the MATLAB software application. The results showed that at the CW614N brass alloy machining, the feed rate has the greatest influence on the surface roughness Ra, but the depth of cut has the greatest influence on the vibration intensity.Ministerstvo školstva, vedy, výskumu a športu Slovenskej republiky, (APVV-19-0550); Kultúrna a Edukacná Grantová Agentúra MŠVVaŠ SR, KEGA, (005TUKE-4/2021, 032TUKE-4/2022, SK-CN-21-0046

Effect of the pore shape and size of 3D-printed open-porous ABS materials on sound absorption performance

Noise has a negative impact on our environment and human health. For this reason, it is necessary to eliminate excessive noise levels. This paper is focused on the study of the sound absorption properties of materials with open-porous structures, which were made of acrylonitrile butadiene styrene (ABS) material using additive technology. Four types of structures (Cartesian, Octagonal, Rhomboid, and Starlit) were evaluated in this work, and every structure was prepared in three different volume ratios of the porosity and three different thicknesses. The sound absorption properties of the investigated ABS specimens were examined utilizing the normal incidence sound absorption and noise reduction coefficients, which were experimentally determined by the transfer function method using a two-microphone acoustic impedance tube. This work deals with various factors that influence the sound absorption performance of four different types of investigated ABS material’s structures. It was found, in this study, that the sound absorption performance of the investigated ABS specimens is strongly affected by different factors, specifically by the structure geometry, material volume ratio, excitation frequency of an acoustic wave, material’s thickness, and air space size behind the tested sound-absorbing materials. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.Ministry of Education, Science, Research, and Sport of the Slovak Republic [APVV-19-0550, KEGA 007TUKE-4/2018]; European Regional Development Fund in the Research Centre of Advanced Mechatronic Systems project within the Operational Programme Research, Development and Education [CZ.02.1.01/0.0/0.0/16_019/0000867

Effect of 3D-printed PLA structure on sound reflection properties

3D printing technique is currently one of the promising emerging technologies. It is used in many areas of human activity, including acoustic applications. This paper focuses on studying the sound reflection behavior of four different types of 3D-printed open-porous polylactic acid (PLA) material structures, namely cartesian, octagonal, rhomboid and starlit structures. Sound reflection properties were evaluated by means of the normal incidence sound reflection coefficient based on the transfer function method using an acoustic impedance tube. In this study, various factors affecting the sound reflection performance of the investigated PLA samples were evaluated. It can be concluded that the sound reflection behavior of the tested PLA specimens was strongly affected by different factors. It was influenced, not only by the type of 3D-printed open-porous material structure, but also by the excitation frequency, the total volume porosity, the specimen thickness, and the air gap size behind the tested specimen inside the acoustic impedance tube.CZ.02.1.01/0.0/0.0/16_019/0000867; Ministerstvo školstva, vedy, výskumu a športu Slovenskej republiky: APVV-19-0550; Kultúrna a Edukacná Grantová Agentúra MŠVVaŠ SR, KEGA: 005TUKE-4/2021Ministry of Education, Science, Research, and Sport of the Slovak Republic [APVV-19-0550, KEGA 005TUKE-4/2021]; European Regional Development Fund in the Research Centre of Advanced Mechatronic Systems [CZ.02.1.01/0.0/0.0/16_019/0000867]; Operational Programme Research, Development and Educatio