Journal of Mechanical Engineering 57 (2011) 11

 

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CW Fiber Laser for Second Harmonic Generation

Authors - Vid Novak – Rok Petkovšek – Boštjan Podobnik – Janez Možina

Abstract

We report on a reduced-complexity laser-diode-seeded master-oscillator-power-amplifier setup of a continuous wave fiber laser, with a single-stage ytterbium doped photonic crystal fiber amplifier. The laser is capable of generating up to 7.5 W single-transverse-mode, narrow-linewidth, polarized output suitable for second harmonic generation. The approach used possesses a further power scaling potential.

Keywords - Yb fiber amplifier, MOPA, narrow-linewidth, single mode, polarized output, second harmonic generation

Paper's information

Strojniški vestnik - Journal of Mechanical Engineering 57(2011)11, 789-798
DOI:10.5545/sv-jme.2011.109

CW Fiber Laser for Second Harmonic Generation (pdf)

 

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Structural Analysis of an Articulated Urban Bus Chassis via FEM: a Methodology Applied to a Case Study

Authors - Dario Croccolo ‒ Massimiliano De Agostinis ‒ Nicolò Vincenzi

Abstract

This paper deals with the static structural analysis of an articulated urban bus chassis, carried out with the Finite Elements Method. The purpose of this work is to simulate and forecast the structural response of the chassis, in terms of stress, strain and displacement, under several loading and constraining conditions, which aim at reflecting the actual duty cycle of the bus. A thorough interaction with the customer company allowed the authors to adequately define the loading scheme and to constrain the structure properly. Sensitivity analyses about FEM parameters have been run, in order to achieve an adequate trade off between computational time and results accuracy. Obtained results have been double checked by employing both solid (3D) and shell (2D) elements for each simulation. Eventually, the customer has been notified of critical issues and the related suggested improvements.

Keywords - bus, structure, frame, chassis, case study

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 57(2011)11, 799-809
DOI:10.554.5/sv-jme.2011.077

Structural Analysis of an Articulated Urban Bus Chassis via FEM: a Methodology Applied to a Case Study (pdf)

 

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Calculation of the Combined Torsional Mesh Stiffness of Spur Gears with Two- and Three-Dimensional Parametrical FE Models

Authors - Timo Kiekbusch ‒ Daniel Sappok ‒ Bernd Sauer ‒ Ian Howard

Abstract

The torsional mesh stiffness is one of the most important characteristics of spur gears. This paper presents the development of detailed two- and three-dimensional finite element models which can be used to calculate the torsional mesh stiffness. Using the parametrical design language of the FE software ANSYS the models offer the possibility to generate various different pairs of spur gears and include an adaptive meshing algorithm for the contact zones. Due to the short computation times the 2D model is well suited to simulate a variety of different gear pairs in a short time period. The more complex 3D model features more options in terms of investigating tooth face modifications for further studies. The resulting values of the torsional stiffness can be used – for example – in multi body simulations of gearboxes.
The results from the 2D FEA are used to derive a simple formula for the combined torsional stiffness of spur gears in mesh. The results presented are based on the individual stiffness of the three main components – body, teeth and contact. Hence, the introduced formula uses these three parts to determine
the overall stiffness for a wide range of gears and gear ratio combinations.
Finally, the results from both the two- and three-dimensional finite element model and the derived formula are compared and the results from the 3D model are checked against results obtained by analytical equations.

Keywords - gear dynamic modelling, spur gear, finite element modelling, torsional mesh stiffness, contact stiffness

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 57(2011)11, 810-818
DOI: 10.5545/sv-jme.2010.248

Calculation of the Combined Torsional Mesh Stiffness of Spur Gears with Two- and Three-Dimensional Parametrical FE Models (pdf)

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Implementation of Automatic Identification Technology in a Process of Fixture Assembly/Disassembly

Authors - Gordana Ostojic ‒ Stevan Stankovski ‒ Djordje Vukelic ‒ Milovan Lazarevic ‒ Janko Hodolic ‒ Branko Tadic ‒ Stevan Odri

Abstract

Radio Frequency Identification (RFID) technology presents automatic identification technology that can be used in product life cycle various phases, especially in the manufacturing phase. The analysis of possible application of RFID technology in machining and inspection operations for fixture manufacturing assembly/disassembly process is presented in this paper. Furthermore, assemble/disassemble fixture manufacturing system structure and conception is presented. An analysis involves hardware and software components that the designed system for assembly/disassembly needs to have. Suggested system verification was done in laboratory conditions. Verification uses ninety-six parts and adequate fixtures. The paper concludes with final remarks, discussing advantages and disadvantages of the developed system.

Keywords - fixture, automatic identification, RFID technology

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 57(2011)11, 819-825
DOI:10.5545/sv-jme.2010.131

Implementation of Automatic Identification Technology in a Process of Fixture Assembly/Disassembly (pdf)

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Possibilities of Using Three-Dimensional Optical Scanning in Complex Geometrical Inspection

Authors - Tomaz Brajlih ‒ Tadej Tasic ‒ Igor Drstvensek ‒ Bogdan Valentan ‒ Miodrag Hadzistevic ‒ Vojko Pogacar ‒ Joze Balic ‒ Bojan Acko

Abstract

Non-contact optical three-dimensional measuring, scanning and digitising are increasingly present in quality assurance systems. Simple scanning procedures, high density of data acquired in a single scan, and the possibility of integrated reverse engineering and inspection, are all advantages of optical scanning compared to conventional measuring methods. Due to the three-dimensional acquisition of measuring data, an optical scanner is often considered to be an alternative possibility for coordinate measuring machines. However, the accuracy of the measured data acquired by optical scanning (even with a high-end system) is still far below the level achieved by high-level coordinate measuring machines. This paper examines the possibilities of using a three-dimensional scanner for workpiece inspection. The first part presents a special field of workpiece inspection in which, even with currently achievable accuracy, optical scanning is a viable solution for the inspection of manufactured parts. In addition, the achievable dimensional accuracy of an optical scanner is tested by scanning several gauge blocks. In conclusion, a head to head comparison with a coordinate measuring machine is made by scanning and verifying a sphere.

Keywords - 3D optical scanning, uncertainty of measurement, geometry inspection, rapid manufacturing, reverse engineering, quality assurance

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 57(2011)11, 826-833
DOI:10.5545/sv-jme.2010.152

Possibilities of Using Three-Dimensional Optical Scanning in Complex Geometrical Inspection (pdf)

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Effects of Hot-Water-Pipeline Renovation in a District Heating System

Authors - Andrej Ljubenko ‒ Alojz Poredoš ‒ Miran Zager

Abstract

In this paper the attention is on the heat losses of a main, aboveground supply, hot-water pipeline, whose length is 5430 m. It is situated between the Šoštanj Thermal Power Plant (TEŠ) and the Central Energy Station (CES) Velenje as part of the district heating system in the Šaleška Valley. It was renovated because major heat losses were identified. A numerical analysis and a comparison between the temperature fields of the pipe’s insulation before and after the renovation was performed to discover the main causes for the high heat losses before renovation. An integral measuring method for determining the heat losses was adapted and used to determine the pipeline’s heat losses after the renovation. Taking into consideration the real operating parameters, the annual energy savings and the consequent operational cost reduction, due to the lower heat losses, resulting from the pipeline renovations, are presented. The calculation is made with measured heat-loss coefficients and is therefore based on the real state of the pipeline. The aim is to show the necessity to investigate the heat losses of a hot-water pipeline whose design or state of insulation is questionable.

Keywords - district heating, heat losses, pipeline renovation, thermal bridges

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 57(2011)11, 834-842
DOI:10.5545/sv-jme.2010.227

Effects of Hot-Water-Pipeline Renovation in a District Heating System (pdf)

 

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On the Particles Size Distributions of Diatomaceous Earth and Perlite Granulations

Authors - Dragan V. Petrović ‒ Časlav B. Mitrović ‒ Nataša R. Trišovic ‒ Zorana Z. Golubović

Abstract
When filtering products with a high level of non-soluble solids and containing filtration-inhibiting substances, a variety of different filter aids can be used. Among others, kieselguhr and perlite are possible materials for this purpose. The selection of the granulation that should be applied depends on the filtered liquid medium and the desired retention level. While perlite is most commonly used for rough filtration, kieselguhr is also suitable for more subtile filtration. In the paper, particle size distributions of three kieselguhr granulations and a perlite granulation are analysed. Particle sizes are measured by the morphometric method, commonly used in the microbiology. Basic statistic parameters are calculated for all considered samples and compared. The applicability of hyperbolic and log-hyperbolic functions, in describing the particles size distributions of these granulations is verified. Depending on the imposed filtration requirements, this approach enables simple modelling and composition of a wide variety of different granulations characterised by appropriate particle size distributions from a few available granulations.

Keywords - filtration, kieselguhr, perlite, granulation, particle size distribution

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 57(2011)11, 843-850
DOI:10.5545/sv-jme.2010.050

On the Particles Size Distributions of Diatomaceous Earth and Perlite Granulations (pdf)

 

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Quality Managers’ Estimates of Quality Management Principles Application in Certified Organisations in Transitional Conditions - Is Serbia Close to TQM?

Authors - Vladan Radlovački ‒ Ivan Beker ‒ Vidosav Majstorović ‒ Mladen Pečujlija  ̶  Dragutin Stanivuković ‒ Bato Kamberović

Abstract
For this research, an ad hoc questionnaire was sent to a representative sample of quality managers in Serbian certified organisations to determine their estimate of the quality management principles application (QMPA) as an overall estimate of management commitment to quality management practice. In a stable business environment, high impact of TQM elements application to the QMPA is likely to be expected. Objective parameters (number of employees, form of ownership of organisation, etc.) are not likely to form significant variations in managers’ perceptions of TQM elements.
It is determined that only a few of the selected TQM elements are predictors of a subjective estimate of the QMPA (estimates of QMS, changes after certification, human resource management and process management).
Observed objective parameters (number of employees and whether an organisation is employing a network administrator or not) showed statistically significant variations in estimates of TQM elements.
Research results point to the conclusion that Serbia is yet to take the long journey towards raising awareness about the management commitment to QM and TQM practice. It is possible that other economies in transition also have similar problems in this area.

Keywords - TQM, quality management, questionnaire study, subjective estimate of TQM elements, management commitment, transition

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 57(2011)11, 851-861
DOI:10.5545/sv-jme.2010.204

Quality Managers’ Estimates of Quality Management Principles Application in Certified Organisations in Transitional Conditions - Is Serbia Close to TQM? (pdf)

 

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