Bratislava, Slovakia
Bratislava, Slovakia

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Koetaka Y.,Osaka Institute of Technology | Nakamura A.,Obayashi Corporation | Noue K.,Okayama University of Science | Uchida N.,Welding Research Institute
Journal of Structural and Construction Engineering | Year: 2010

This paper proposes prediction methods of the maximum in-plane shear force acting on floor slab for transmitting to plane frame the inertial force due to earthquake. And, time history response analysis are conducted, in order both to confirm prediction methods and to verify effects of structural parameters on the maximum in-plane shear force. As a result, following conclusions can be obtained; (1) the maximum in-plane shear force converges to the value of the rigid floor slab after indicating the maximum value, as in-plane stifness of floor slab becomes larger, and (2) proposed prediction methods agree with time history responses qualitatively.

Kumar K.A.,National Institute of Technology Tiruchirappalli | Sundareswaran K.,National Institute of Technology Tiruchirappalli | Venkateswaran P.R.,Welding Research Institute | Palani S.,Sudharsan Engineering College | Jairath A.K.,Amity University
2015 International Conference on Recent Developments in Control, Automation and Power Engineering, RDCAPE 2015 | Year: 2015

The solar photovoltaic power generation is one of the fast growing renewable energy source of electrical power. There are two main types of solar PV power generation systems: grid connected and off-grid systems. Grid connected systems are referred as distributed generators as they feed electrical power into the utility grid from various stations. The grid connected systems create certain problems in stability and power quality of the utility grid. One among the major problem is islanding phenomenon. Anti-islanding is an essential feature of every live grid connected solar PV inverter to prevent it islanding during a grid failure. This paper discusses the details of implementation and test results obtained from anti-islanding tests conducted on three phase grid connected 20 kWp solar photovoltaic power system in a reputed manufacturing industry in India. © 2015 IEEE.

Brziak P.,Welding Research Institute | Lomozik M.,Institute of Welding | Mizuno R.,Japan Power Engineering and Inspection Corporation JAPEIC | Matsuda F.,Japan Power Engineering and Inspection Corporation JAPEIC
Archives of Metallurgy and Materials | Year: 2011

SQV2A Manganese-Molybdenum-Nickel ferritic steel has been developed for pressure vessel fabrication. Due to its chemical composition and carefully controlled heat treatment the SQV2A steel consists of fine-grained tempered martensite/lower bainite microstructure, which exhibits well-balanced combination of strength and low temperature toughness. However, this balance is disturbed by the thermal cycles experienced during welding, producing areas of unaccepted mechanical behaviors. Generally, a decrease in toughness of some regions of BM Heat Affected Zone is the most critical aspect of multi-layer (repair) welding. A full scale Post Welding Heat Treatment (PWHT) usually restores the mechanical behaviors to requested levels. Additionally, PWHT removes hydrogen trapped in the microstructure during welding. A situation becomes critical, when on-site local (repair) welding takes place. Harsh environment, difficult access and a presence other facilities make the in-situ PWHT almost inapplicable. In term of cold cracking prevention, a Gas Tungsten arc Welding (GTAW) gives acceptable hydrogen levels in the weld region; and full scale PWHT is unnecessary. This is the main reason why the GTAW has become a leading process for on-site (repair) welding of heavy section components. Moreover, a automatic GTAW process offers better weld geometry controlling which has become out of importance for welding not followed by PWHT. A precisely controlled multiple weld thermal cycles of predefined peak temperatures in particular weld regions can be employed for restoring the mechanical behavior of critical weld areas instead of full scale PWHT.

Mraz L.,Welding Research Institute | Karlsson L.,University College West | Vrana M.,Nuclear Physics Institute of Czech Republic | Mikula P.,Nuclear Physics Institute of Czech Republic
EAN 2014 - 52nd International Conference on Experimental Stress Analysis | Year: 2014

In this contribution the results of residual strain/stress measurements performed on several single pass fillet steel welds which were carried out at different welding conditions, namely, with different filler materials are presented.

Sharma A.,Indian Institute of Technology Hyderabad | Verma D.K.,Welding Research Institute | Arora N.,Indian Institute of Technology Roorkee
International Journal of Advanced Manufacturing Technology | Year: 2016

Weld bead geometry is a complex multi-input multi-output system. The relation between every individual geometrical feature and welding process parameter of a weld bead is unique, like the weld width, reinforcement height, and penetration depth. A comprehensive assessment scheme for weld bead geometry is proposed. Individual effects of weld bead geometry features were aggregated to obtain an index as a function of the process parameters to express the overall geometric fitness. The proposed approach is demonstrated through a case study on pulsed tungsten inert gas welding. The method is simple but more effective than other methods of aggregation, like the average index, desirability function, and fuzzy classification used in similar scenarios. The developed approach may be used for other manufacturing processes where complex multi-input multi-output relations govern the overall efficacy. © 2015, Springer-Verlag London.

Cicka R.,Slovak University of Technology in Bratislava | Bakajova J.,Welding Research Institute | Stefanikova M.,Slovak University of Technology in Bratislava | Domankova M.,Slovak University of Technology in Bratislava | Janovec J.,Slovak University of Technology in Bratislava
Journal of Mining and Metallurgy, Section B: Metallurgy | Year: 2012

The precipitation of secondary phases was investigated in the 0.17C-16Cr-11Mn-0.43N austenitic stainless steel during annealing at 800 and 850°C for times between 5 min and 100 h. Light microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, scanning electron microscopy, and differential thermal analysis were used in experiments. Thermodynamic calculations were done by the Thermo-Calc database software package. Cr2N and M23C6 were considered to be stable phases at the annealing temperatures. Cells consisting of alternating Cr2N and austenite lamellae were observed in the steel microstructure after sufficiently long annealing. The metastable chi phase was also found in all the annealed samples. After 100 h of annealing the equilibrium sigma started to precipitate. The thermodynamically predicted M6C was not confirmed experimentally in any of the annealed samples. DTA analysis showed the initial precipitation stage was followed by the phase dissolution. For the investigated steel the computational thermodynamics can be used only for qualitative interpretation of the experimental results as the measured endothermal peaks were found to be shifted of about 50÷70°C related to the computed results.

Mikus R.,Slovak University of Agriculture | Szabo V.,Slovak University of Agriculture | Drlicka R.,Slovak University of Agriculture | Bakajova J.,Welding Research Institute
Advanced Materials Research | Year: 2014

The paper deals with the hardness, chemical composition (using spectrometer) and microstructure (using light microscopy and scanning electron microscopy with EDX spot analysis) of the weld deposit based on Fe-Cr-Ni used for renovation of the functional surface of wheel for mineral wool spinning and with impacts of operational processes onto these characteristics. Deposit samples were analysed after service wear having an abrasive-erosive-thermal character. Analysis results were compared to a deposit sample with no wear. Based on results of weld deposit microstructure analysis, duplex ferrite-austenitic structure with ferrite matrix and austenite precipitation in various morphologies was found in the all cases. No substantial hardness changes caused by operational processes were found by comparing the analyses results. Increased melt temperature was the most important process parameter affecting the chemical and phase composition of the examined material, inducing the precipitation of new phase with a high Cr content. © (2014) Trans Tech Publications, Switzerland.

Mohan Kumar J.,Manipal Center for Information science | Venkateswaran P.R.,Welding Research Institute | Gopalakrishna Kini N.,Manipal University India | Sundaresan C.,Manipal Center for Information science
Sensors and Transducers | Year: 2012

Wireless Sensor Networks (WSNs) are being used for a large number of location-dependent applications, where the measurement data is meaningless without accurate location of its origin. In many of these applications, where coarse accuracy is sufficient, range free localization techniques are being pursued as low cost alternative to the range based localization techniques. In this paper, we present range free Circle intersection combined with fuzzy weighted centroid method for localization. It's an effective soft computing and geometric algorithm for localization. Result of implementation show that this algorithm can be a better substitution for current methods because of lower expense and simple implementation. In these proposed techniques, we consider the edge weight of each anchor node separately and combine them to compute the location of sensor nodes. The edge weights are modeled by the fuzzy logic systems. The simulation results demonstrate the effectiveness of proposed schemes. © 2012 IFSA.

Bernasovsky P.,Welding Research Institute | Brziak P.,Welding Research Institute | Orszaghova J.,Welding Research Institute | Kosinova A.,Welding Research Institute | And 2 more authors.
Materials Science Forum | Year: 2016

The contribution summarizes some corrosion case studies of the welded steel structures, which happened in Slovakia last years. Features of cracking are illustrated on real cases of breakdowns in the petrochemical industry (SSCC and PTA-SCC of stainless steel), at a cement works (LME of AISI 310 steel due to Ni3S2 attack), at a gas pipeline (LME caused by remelted Cu) and in the water meters & tubes made of stainless steel (MIC). © 2016 Trans Tech Publications, Switzerland.

Smetana S.,Welding Research Institute | Sefcik D.,Welding Research Institute | Tybitancl B.,Welding Research Institute
Proc. of the Int. Conf. on Advances in Welding Science and Technology for Construction, Energy and Transportation, AWST 2010, held in Conj. with the 63rd Annual Assembly of IIW 2010 | Year: 2010

Hot spraying of coatings is one of modern methods of formation of specific layers resistant to stringent wear conditions. The paper presents information on two-phase hot flame spraying of coatings on CCrBSiNi basis used for surface treatment of huge components, e.g. feed rollers subject to abrasion-adhesion wear in combination with thermal fatigue and corrosion.

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