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  • 701.
    Wanner, Bertil
    et al.
    University West, Department of Engineering Science, Division of Production Engineering.
    Eynian, Mahdi
    University West, Department of Engineering Science, Division of Production Engineering.
    Beno, Tomas
    University West, Department of Engineering Science, Division of Production Engineering.
    Pejryd, Lars
    University West, Department of Engineering Science, Division of Production Engineering.
    Process Stability Strategies in Milling of Thin-walled Inconel 7182011In: 4th Manufacturing Engineering Society International Conference / [ed] Manufacturing Engineering Society, 2011, p. 1-8-Conference paper (Refereed)
    Abstract [en]

    Trends in Aerospace development have led to thin-walled, reduced-weight engine designs. The demands in manufacturing have forced production speeds and material removal rates (MRR) to increase. As component wall thickness gets thinner, the consequence oftentimes is an increase in chatter vibrations. This paper suggests that a correctly chosen tool-to-workpiece offset geometry may lead to a robust and chatter free process. The results show the differences in force response for three geometries while varying the height overhang of the workpiece. This is part of a concerted effort to develop a robust methodology for the prediction of chatter vibrations during milling operations of thin-walled Aerospace components. This paper gives guidelines on how to accomplish robust machining practices. It also answers the following questions: How critical is the choice of offset between tool and workpiece during milling setup? And what effects do the entry and exit of cut have on system vibrations?

  • 702.
    Wennberg, Johan
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Isothermal oxidation behaviour of HVAF-sprayed Ni-based coatings2016Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    High temperature corrosion of metallic materials in biomass and waste fired boilers, is a major challenge in utilization of green heat and power production from renewable fuels. Particularly, the pressure bearing parts such as superheater tubes and water walls are prone to extensive corrosion, and thereby limit the electrical efficiency of the boiler. A promising route to improve the durability of degradation-prone components, such as above, is applying a protective coating that has inherently better corrosion resistance. Without the need for improved mechanical stability, the coating material can primarily be optimized to ensure superior corrosion behaviour in the anticipated boiler environment.Thermal spray technique is proposed as a potential solution to insulate the components from the corrosive environment by applying a protective coating. In the present work, the oxidation behaviour of four Ni-based coatings, produced by high-velocity air fuel (HVAF) process is investigated. NiCr, NiAl, NiCrAlY and CorEr powders were used to spray on low-alloyed ferritic steel 16Mo3 substrate. Different HVAF process parameters were initially used to obtain optimized coatings in terms of high density and low porosity. The setting that generated the densest coating was selected and applied to succeeding spraying sessions. The austenitic stainless steels Sanicro 25, stainless steel 304L, as well as 16Mo3 were selected as the reference materials to compare the oxidation results. The coated and uncoated samples were exposed to an ambient air environment with a temperature of 600°C with different time intervals up to 168h. The oxidation behaviour of samples was investigated after different stages of heat exposure utilizing SEM/EDS and XRD analysis.The coatings were graded based on their oxidation performance in the test environment. The ranking for the coatings is (from the best to worst): NiCrAlY> NiAl> NiCr > CorEr. For the reference materials, the ranking is (from the best to worst): 304L>Sanicro 25> 16Mo3.

  • 703.
    Wiklund, Daniel
    et al.
    Swerea IVF.
    Larsson, Mats
    University West, Department of Engineering Science, Division of Process and Product Development.
    A friction model for the boundary and mixed lubricated regimes in sheet metal forming2012Conference paper (Refereed)
    Abstract [en]

    Friction is an important parameter to control in sheet metal forming since it influences the flow of material in the process. Consequently, it is also an important parameter in the design process of new stamping dies when numerical simulations are utilized. Today, the most commonly used friction model in forming simulations is Coulomb´s friction which is a strong simplification of the tribological system. In this work an advanced friction model is developed, which considers properties of tool and sheet surface topography (spatial and height), lubricant, sheet material, and process parameters such as sliding speed and contact pressure. The results show that the model can predict the frictional behavior over a wide range of influencing parameters. A regression analysis of model and experimental results, Bending-Under-Tension friction test, shows acorrelation of R2=0.89.

  • 704.
    Wärmefjord, Kristina
    et al.
    Chalmers University of Technology, Dept. of Product and Production Development, SE-412 96 Gothenburg, Sweden.
    Söderberg, Rikard
    Chalmers University of Technology, Dept. of Product and Production Development, SE-412 96 Gothenburg, Sweden.
    Ericsson, Mikael
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Appelgren, Anders
    University West, Department of Engineering Science, Division of Production Systems.
    Lundbäck, Andreas
    Luleå University of Technology, Dept. of Engineering Sciences and Mathematics, SE-971 87 Luleå, Sweden.
    Lööf, Johan
    GKN Aerospace,Engine Systems, SE-461 81 Trollhättan, Sweden .
    Lindkvist, Lars
    Chalmers University of Technology, Dept. of Product and Production Development, SE-412 96 Gothenburg, Sweden.
    Svensson, Hans-Olof
    GKN Aerospace,Engine Systems, SE-461 81 Trollhättan, Sweden .
    Welding of non-nominal geometries: physical tests2016In: Procedia CIRP, ISSN 2212-8271, E-ISSN 2212-8271, Vol. 43, p. 136-141Article in journal (Refereed)
    Abstract [en]

    The geometrical quality of a welded assembly is to some extent depending part positions before welding. Here, a design of experiment is set up in order to investigate this relation using physical tests in a controlled environment. Based on the experimental results it can be concluded that the influence of part position before welding is significant for geometrical deviation after welding. Furthermore, a working procedure for a completely virtual geometry assurance process for welded assemblies is outlined. In this process, part variations, assembly fixture variations and welding induced variations are important inputs when predicting the capability of the final assembly.

  • 705.
    Yehorov, Yuri
    et al.
    Center for Research and Development of Welding Processes, Federal University of Uberlandia, Uberlândia, Brazil.
    da Silva, Leandro João
    Center for Research and Development of Welding Processes, Federal University of Uberlandia, Uberlândia, Brazil.
    Scotti, Americo
    University West, Department of Engineering Science, Division of Welding Technology. Center for Research and Development of Welding Processes, Federal University of Uberlandia, Uberlândia, Brazil.
    Balancing WAAM Production Costs and Wall Surface Quality through Parameter Selection: A Case Study of an Al-Mg5 Alloy Multilayer-Non-Oscillated Single Pass Wall2019In: Journal of Manufacturing and Materials Processing, E-ISSN 2504-4494, Vol. 3, no 2, p. 1-19Article in journal (Refereed)
    Abstract [en]

    The purpose of the study was to propose a strategy to assess the potential reduction of the production cost during wire+arc additive manufacturing (WAAM) based on the combination of wire feed speed (related to deposition rate) and travel speed (related to deposition time). A series of experiments, using a multilayer-non-oscillated single pass wall made of an Al-Mg alloy, was conducted. The quality of the wall was assessed through the lateral surface waviness and top layer undulation. The concepts of Surface Waviness and Buy-to-Apply indices were introduced. Initially, the range of travel speed (TS) that provided layers with acceptable quality was determined for a given wire feed speed (WFS), corresponding to a constant current. Then, the effect of the increase of production capacity of the process (though current raising, yet maintaining the ratio WFS/TS constant) on the wall quality for a given condition within the TS range was assessed. The results showed that the useful range of TS prevents too rough a waving surface below the lower limit and top surface undulation over the higher limit. However, inside the range, there is little quality variation for the case under study. Finally, simulations of deposition time were developed to demonstrate the weight of the TS on the final deposition time and wall quality as a function of a target wall width. This respective weight showed the existence of a complex and unpredictable, yet determined, power of a combination of TS, target wall geometry, and dead time between subsequent layers. It was verified to be possible to find optimized TS as a function of different target geometries. 

  • 706.
    Zachrisson, Jan
    et al.
    University West, Department of Engineering Science, Division of Mechanical Engineering.
    Börjesson, J
    ESAB AB.
    Karlsson, Leif
    University West, Department of Engineering Science, Division of Mechanical Engineering.
    Role of inclusions in formation of high strength steel weld metal microstructures2013In: Science and technology of welding and joining, ISSN 1362-1718, E-ISSN 1743-2936, Vol. 18, no 7, p. 603-609Article in journal (Refereed)
    Abstract [en]

    A series of high strength weld metals with varying Al content are studied. The inclusions are characterised using energy dispersive X-ray analysis and electron diffraction. The tendency for alignment of the microstructure is characterised quantitatively using electron backscatter diffraction and a recently developed post-processing technique. Correlation is found between the inclusion phases present and the amount of aligned neighbouring grains in the microstructure. It is shown that amorphous Si-Al oxides form at low Al weld metal contents and an Mg-Al spinel at higher contents. The former is associated with less alignment of the microstructure and therefore higher impact toughness. The effect of these inclusions on the formation of the microstructure is discussed.

  • 707.
    Zachrisson, Jan
    et al.
    University West, Department of Engineering Science, Research Environment Production Technology West.
    Börjesson, Johan
    ESAB AB, Lindholmsallén 9, Box 8004, SE-40277 Gothenburg.
    Karlsson, Leif
    University West, Department of Engineering Science, Division of Manufacturing Processes.
    A new EBSD based methodology for the quantitative characterisation of microstructures formed by displacive fcc–bcc transformations2013In: Micron, ISSN 0968-4328, E-ISSN 1878-4291, Vol. 45, no February, p. 45-54Article in journal (Refereed)
    Abstract [en]

    This work is concerned with a new methodology that can be used to quantify the degree to which grains in the microstructure are aligned in the form of packets. The methodology is based on a crystallographic definition of the term packet which is used to deduce the theoretically ideal misorientations of intra-packet grain boundaries. A misorientation distribution obtained from extensive EBSD mapping can thus be split into intra- and inter-packet misorientations and the corresponding fractions can be determined by integration. The theoretical framework of the methodology is explained and a step-by-step description of the procedure is given. Results from a trace analysis are provided to justify the assumptions made regarding habit plane and examples are included showing how the grain boundary network can be split into two separate parts, one for lath boundaries and the other for packet boundaries. Moreover, example weld metal microstructures along with the corresponding misorientation distributions as well as quantitative values of the microstructures are presented.

  • 708.
    Zhang, Jing
    University West, Department of Engineering Science, Division of Welding Technology.
    Conceptual Design of a Novel Continuous Nanoparticle Production Equipment for Energy Efficient Sintering and Additive Manufacturing2018Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Materials in nanoscale possess interesting features such as depression of melting point, increased chemical reactivity, improved mechanical, electrical and thermal properties. Today, nanoparticles (NPs) are generally produced using chemical synthesis routes and other top down methods. These processes suffer generally from issues such as low production yield and require complex precursors that may have large environmental concerns. NPs, especially spherical NPs, are very interesting in bringing down sintering temperature for sinter alloys and act as nucleation sites for crystal growth in, for instance, additive manufacturing processes. These features lead to decreased energy consumption and improved mechanical performance of additively manufactured products. Therefore, manufacturing of NPs in large scale is of great interest for future industrial development.

    The purpose of the present thesis work is to carry out a feasibility design study for a novel nanoparticle manufacturing equipment concept using a novel two coupled axis concept for producing NPs in larger quantities.

    The method is based on Consumable Electrode Direct Current Arc (CEDA, also called spark erosion) using two vertically aligned parallel electrodes, thus significantly increasing the yield of the NPs production. Before the start of the design work, a theoretical study was carried out to understand the state-of-the-art of the nanoparticle manufacturing processes available. It was followed by a novel design concept for a new equipment that can dramatically increase the yield of the NPs production compared to the state-of-the-art. The work is carried out using the Software Solidworks2016. A 3D model of the new machine concept using the novel design was built. A simulation of the control system based on the Software Proteus was carried out.

    This novel equipment can potentially offer continuous and larger scale and production of NPs which is useful for energy efficient sintering and for efficient control of grain size in additive manufacturing process, thus making a better product in the fast-growing additive manufacturing business sector.

  • 709.
    Zhang, Pimin
    et al.
    Linköping University, Department of Management and Engineering, Linköping, SE-58183, Sweden.
    Sadeghi, Esmaeil
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Chen, Shula
    Linköping University, Department of Physics, Chemistry, and Biology, Linköping, SE-58183, Sweden.
    Li, Xin-Hai
    Siemens Industrial Turbomachinery AB, Finspång, SE-61283, Sweden.
    Markocsan, Nicolaie
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Joshi, Shrikant V.
    University West, Department of Engineering Science, Research Enviroment Production Technology West.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry, and Biology, Linköping, SE-58183, Sweden.
    Buyanova, Irina A.
    Linköping University, Department of Physics, Chemistry, and Biology, Linköping, SE-58183, Sweden.
    Peng, Ru L.in
    Linköping University, Department of Management and Engineering, Linköping, SE-58183, Sweden.
    Effects of surface finish on the initial oxidation of HVAF-sprayed NiCoCrAlY coatings2019In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 364, p. 43-56Article in journal (Refereed)
    Abstract [en]

    Oxide scale formed on HVAF-sprayed NiCoCrAlY coatings and the effect of surface treatment were investigated by a multi-approach study combining photo-stimulated luminescence, microstructural observation and mass gain. The initial oxidationbehaviour of as-sprayed, polished and shot-peened coatings at 1000 °C is studied. Both polished and shot-peened coatings exhibited superior performance due to rapid formation of α-Al2O3 fully covering the coating and suppressing the growth of transient alumina, assisted by a high density of α-Al2O3 nuclei on surface treatment induced defects. Moreover, the fast development of a two-layer alumina scale consisting of an inward-grown inner α-Al2O3 layer and an outer layer transformed from outward-grown transient alumina resulted in a higher oxide growth rate of the as-sprayed coating.

  • 710.
    Zhang, Pimin
    et al.
    Linköping University, Department of Management and Engineering, Linköping, Sweden.
    Sadeghimeresht, Esmaeil
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Peng, Ru Lin
    Linköping University, Department of Management and Engineering, Linköping, Sweden.
    Li, Xin-Hai
    Siemens Industrial Turbomachinery AB, Finspång, Sweden.
    Markocsan, Nicolaie
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Joshi, Shrikant
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Johansson, Sten
    Linköping University, Department of Management and Engineering, Linköping, Sweden.
    Isothermal oxidation behavior of HVAF-sprayed NiCoCrAlY coatings: Effect of surface treatment2017In: Proceedings of the International Thermal Spray Conference & Exposition (ITSC 2017), New York: Curran Associates, Inc , 2017, Vol. 1, p. 456-461Conference paper (Refereed)
    Abstract [en]

    NiCoCrAlY coatings are widely used as bond coats for ceramic thermal barrier coatings (TBCs) andoxidation and corrosion protective overlay coatings in industrial gas turbines. High temperature oxidation behaviour of NiCoCrAlYs has a great influence on the coating performance and lifetime of TBCs. A promising route to decrease the oxidation rate of such coatings is post-coating surface modification which can facilitate formation of a uniform alumina scale with a considerably slower growth rate compared to the as-sprayed coatings. In this work, the effect of surface treatment by means of shot peening and laser surface melting (LSM) on the oxidation resistance of high velocity air-fuel (HVAF) sprayed NiCoCrAlY coatings was studied. Isothermal oxidation was carried out at 1000⁰C for 1000h. Results showed that the rough surface of as-sprayed HVAF sprayed coatings was significantly changed after shot peening and LSM treatment, with a compact and smooth appearance. After the exposure, the oxide scales formed on surface-treated NiCoCrAlY coatings showed different morphology and growth rate compared to those formed on as-sprayed coating surface. The oxidation behaviour of surface treated HVAF-sprayed NiCoCrAlY coatings were revealed and discussed.

  • 711.
    Zhang, Xun
    et al.
    The University of Manchester, Henry Moseley X-ray Imaging Facility, The Henry Royce Institute, School of Materials, M13 9PL, Manchester, United Kingdom.
    Li, Chun
    State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin, 150001, China; The University of Manchester, School of Materials, M13 9PL, Manchester, United Kingdom.
    Withers, Philip J.
    The University of Manchester, Henry Moseley X-ray Imaging Facility, The Henry Royce Institute, School of Materials, M13 9PL, Manchester, United Kingdom.
    Markocsan, Nicolaie
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Xiao, Ping
    The University of Manchester, School of Materials, M13 9PL, Manchester, United Kingdom.
    Determination of local residual stress in an air plasma spray thermal barrier coating (APS-TBC) by microscale ring coring using a picosecond laser2019In: Scripta Materialia, ISSN 1359-6462, E-ISSN 1872-8456, Vol. 167, p. 126-130Article in journal (Refereed)
    Abstract [en]

    A picosecond laser for incremental annular trench cutting is combined with digital image correlation (DIC) to extend the incremental ring-core method to the profiling of residual stress in thick (>100 μm) coatings. In this case the local residual stress in a TBC is depth profiled after exposure to 1150 °C for 190 h. The topcoat was found to be in compression with an average compressive stress of −94 ± 8 MPa which is representative of the stresses that would be generated elastically on cooling from a stress-free temperature of ~970 °C. The stress profile measurements have been validated by high-energy synchrotron X-ray diffraction measurements. © 2019

  • 712.
    Zou, Zhonghua
    et al.
    Shanghai Jiao Tong University, Shanghai Key Laboratory of Advanced High-temperature Materials and Precision Forming, Shanghai 200240, China .
    Donoghue, Jack
    University of Manchester, School of Materials, Grosvenor Street, Manchester M1 7HS, UK .
    Curry, Nicholas
    University West, Department of Engineering Science, Division of Mechanical Engineering.
    Yang, Lixia
    Shanghai Jiao Tong University, Shanghai Key Laboratory of Advanced High-temperature Materials and Precision Forming, Shanghai 200240, China .
    Guo, Fangwei
    Shanghai Jiao Tong University, Shanghai Key Laboratory of Advanced High-temperature Materials and Precision Forming, Shanghai 200240, China .
    Nylén, Per
    University West, Department of Engineering Science, Division of Production Engineering.
    Zhao, Xiaofeng
    Shanghai Jiao Tong University, Shanghai Key Laboratory of Advanced High-temperature Materials and Precision Forming, Shanghai 200240, China .
    Xiao, Ping
    Shanghai Jiao Tong University, Shanghai Key Laboratory of Advanced High-temperature Materials and Precision Forming, Shanghai 200240, China .
    A comparative study on the performance of suspension plasma sprayed thermal barrier coatings with different bond coat systems2015In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 275, p. 276-282Article in journal (Refereed)
    Abstract [en]

    The performance of suspension plasma sprayed (SPS) yttria stabilized zirconia (YSZ) thermal barrier coatings (TBCs) after isothermal treatment at 1150. °C was investigated. The NiCoCrAlY bond coats were applied by air plasma spray (APS) and high velocity oxygen fuel (HVOF) techniques. It was found that the microstructure of SPS TBCs depends on the surface morphology of the bond coat. The SPS TBCs with a rough APS bond coat exhibited a longer lifetime than those with a smooth HVOF bond coat. To understand this phenomenon, the evolution of the microstructure, mechanical properties and the residual stresses in the TBCs and TGO were systematically studied. Results showed that the surface roughness and oxidation behavior of the bond coat play dominant roles in the SPS TBC failure. © 2015.

  • 713.
    Zouity, Amina
    University West, Department of Engineering Science, Division of Mechanical Engineering and Natural Sciences.
    Parameterstudie om lasersvetsning av en nickelbaslegering2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The bachelor's thesis has been performed at Siemens Industrial Turbomachinery AB in Trollhättan, Sweden. The aim of this bachelor's thesis was to identify problem in a welding process in order to improve the weld quality. Based on statistical experiment four factors were evaluated with DOE method and ten experiments in material 2 mm Hastelloy X was performed with Siemens fiber laser (3D Prima Laserdyne 795). The factors weld speed,shield gas, focal point and laser power were the four welding parameters that varied in the experiment, in order to evaluate the factor effects on pores and joint geometry in the welds. Plane test plates were created to the experiments and brainstorming with the personal at Siemens in order to identify which factors to choose for the experiments. To evaluate pores and joint geometry the test plates was x-rayed, sectioned, polished and etched. Joint geometry was measured and photographed with microscope. Statistical analyze was performed with Minitab to estimate the factors effect on pores and joint geometry.Problem in the weld process was identified based on the ten experiments, which werepores and critical dimensions for the joint geometry. A conjunction for the pores and joint geometry was identified. The conjunction was if pores occur in the weld joint the joint geometry affects negatively too, but it's not statistical verified. The weld process have been identified to be unstable based on the statistical analyze that been performed. The weld process needs to be further evaluated, to identify confounding factors, which affect the stability of the welding process. One of the ten experiments was closest to the criterias for approved weld joint. The experiment that was closest to the criteria's for approved weldjoint is recommended for further work to Siemens. The welding parameters that are recommended to be evaluated further are laser power and the interaction factor welding speed and shielding gas, which can have a significant impact on the pores and joint geometry based on the statistical analysis performed by Minitab.

  • 714.
    Åkerfeldt, Pia
    et al.
    Luleå University of Technology,Division of Materials Science, Luleå, Sweden.
    Hörnqvist Colliander, Magnus
    Chalmers University of Technology, Department of Physics, Göteborg, Sweden.
    Pederson, Robert
    University West, Department of Engineering Science, Division of Welding Technology. Luleå University of Technology,Division of Materials Science, Luleå, Sweden.
    Antti, Marta-Lena
    Luleå University of Technology,Division of Materials Science, Luleå, Sweden.
    Electron backscatter diffraction characterization of fatigue crack growth in laser metal wire deposited Ti-6Al-4V2018In: Materials Characterization, ISSN 1044-5803, E-ISSN 1873-4189, Vol. 135, p. 245-256Article in journal (Refereed)
    Abstract [en]

    By additive manufacturing (AM) there is a feasibility of producing near net shape components in basically one step from 3D CAD model to final product. The interest for AM is high and during the past decade a lot of research has been carried out in order to understand the influence from process parameters on the microstructure and furthermore on the mechanical properties. In the present study laser metal wire deposition of Ti-6Al-4V has been studied in detail with regard to its fatigue crack propagation characteristics. Two specimen orientations, parallel and perpendicular to the deposition direction, have been evaluated at room temperature and at 250 °C. No difference in the fatigue crack growth rate could be confirmed for the two specimen orientations. However, in the fractographic study it was observed that the tortuosity varied between certain regions on the fracture surface. The local crack path characteristic could be related to the alpha colony size and/or the crystallographic orientation. Moreover, large areas exhibiting similar crystallographic orientation were observed along the prior beta grain boundaries, which were attributed to the wide alpha colonies frequently observed along the prior beta grain boundaries. © 2017 Elsevier Inc.

  • 715.
    Åstrand, Erik
    University West, Department of Engineering Science, Research Enviroment Production Technology West.
    A Framework for optimised welding of fatigue loaded structures: Applied to gas metal arc welding of fillet welds2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Welding is a key process for heavy steel structures, but it is also a weak link in the structure since fatigue fractures in welds are a common cause of failure. This thesis proposes several changes in order to improve the fatigue properties in acost effective way, enabling reduced weight and reduced cost of welded structures. The main idea is to adapt the weld requirements and welding procedures to the load conditions of the weld. This approach ensures that the main focus in the welding process is the critical characteristics of the welds fatigue life properties. The fatigue life critical properties are most often related to the geometrical factors of the weld such as the radius at the weld toe or the penetration in the root. The thesis describes a holistic view of the subject and covers fatigue, weld quality, weld requirements and welding procedures. It becomes evident that the traditional way of working without a direct connection to fatigue is not the best. With an adaptation to the load conditions and fatigue, it is possible to enhance the fatigue life and reduce the welding cost. The main challenge is to connect the welding process, weld requirements and fatigue life properties. It is needed for an optimised welding process of heavy structures subjected to fatigue and toget a predictable fatigue life. Welds optimised for enhanced fatigue life properties are not necessary accepted according to the requirements in a current standard. Several welding procedures are proposed for improving the fatigue life properties of the weld, which indicate a high potential for enhanced fatigue lifeof fillet welds. The idea is to replace the "standard" fillet weld with three different weld types: (i) Welds with deep penetration, (ii) Welds with large weld toe radius and (iii) Welds produced with low cost. Together with customised requirements and reduced over-welding there is a vast potential for reduced weight, reduced cost and increased productivity.The main contribution of this thesis work is the cross-functional studies including design, analysis, production and quality control. This gives a framework for improvements supporting reduced cost and reduced weight of VIII welded structures without reducing the fatigue strength. Many shortcomings have been highlighted to change the welding from a state where welds are done in a way as they "always" have, by tradition, to a more contemporary situation where weld requirements and welding procedures are actively chosen to match the load conditions of the weld. This result in requirements and welding procedures which actually are connected to the fatigue properties as defined by the loading conditions, and where auditors with high probability can say that an accepted weld actually is better than a rejected weld.

  • 716.
    Åstrand, Erik
    University West, Department of Engineering Science, Research Environment Production Technology West.
    Key Changes in the Welding of Fatigue Loaded Structures2014In: Proceedings of the 6th International Swedish Production Symposium 2014 / [ed] Stahre, Johan, Johansson, Björn & Björkman, Mats, 2014, p. 1-7Conference paper (Refereed)
    Abstract [en]

    This paper discusses welding problems of today and the possibilities for tomorrow for companies in the welding industry. By leaving old welding procedures based on traditions and applying new scientifically developed welding demands and procedures there is a vast potential to improve strength performance of the structures and increased competitiveness regarding weld work for the companies. Unfortunately, no changes are done easily and quickly and this paper gives proposals how changes can be done efficiently.

  • 717.
    Åstrand, Erik
    University West, Department of Engineering Science, Research Enviroment Production Technology West.
    The Ad Hoc Nature of Weld Quality and Welding Procedures for Fatigue2013In: Design, Fabrication and Economy of Metal Structures: International Conference Proceedings 2013, Miskolc, Hungary, April 24-26, 2013 / [ed] Jármai, Károly, Farkas, József (Eds.), Berlin: Springer, 2013, p. 243-248Conference paper (Refereed)
  • 718.
    Åstrand, Erik
    University West, Department of Engineering Science, Research Environment Production Technology West.
    Weld Procedures and Demands for Improved Fatigue Strength of Single Load Carrying Fillet Welds2013In: Trends in Welding Research: Proceedings of the 9th International Conference / [ed] T. DeRoy, S.A. David, T. Koseki, H. Basdeshia, Chicago: ASM International, 2013, p. 798-804Conference paper (Refereed)
    Abstract [en]

    Traditional weld demands on throat size and leg length does not support a welding process for improved penetration. This paper includes theoretical analysis of welded samples showing the potential with welds that have a prescribed asymmetry. Weld with a larger leg length against the web plate offer in this study improved fatigue properties and could also offer potential for reduced welding time, a smaller amount of filler material and potentially make the quality inspection more relevant. Copyright © 2013 ASM International® All rights reserved.

  • 719.
    Åstrand, Erik
    et al.
    University West, Department of Engineering Science, Research Enviroment Production Technology West.
    Bolmsjö, Gunnar
    University West, Department of Engineering Science, Division of Automation Systems.
    Sikström, Fredrik
    University West, Department of Engineering Science, Division of Automation Systems.
    Lindgren, Eric
    Improved fatigue properties of welded box beams by tailored welding procedures for high penetration fillet weldsIn: Journal of materials engineering and performance (Print), ISSN 1059-9495, E-ISSN 1544-1024Article in journal (Other academic)
  • 720.
    Åstrand, Erik
    et al.
    University West, Department of Engineering Science, Research Enviroment Production Technology West. Volvo Construction Equipment AB, Braås, Sweden .
    Stenberg, T.
    Royal Institute of Technology (KTH), Department of Aeronautical and Vehicle Engineering, Division of Lightweight Structures, Stockholm, Sweden .
    Jonsson, B.
    Volvo Construction Equipment AB, Braås, Sweden .
    Barsoum, Z.
    Royal Institute of Technology (KTH), Department of Aeronautical and Vehicle Engineering, Division of Lightweight Structures, Stockholm, Sweden .
    Welding procedures for fatigue life improvement of the weld toe2016In: Welding in the World, ISSN 0043-2288, E-ISSN 1878-6669, Vol. 60, no 3, p. 573-580Article in journal (Refereed)
    Abstract [en]

    This paper presents the results of an experimental study of gas metal arc welded, GMAW, cruciform joints made of common construction steel S355. The hypothesis is that smooth undercuts in as welded conditions can give enhanced fatigue properties similarly as post treated welds. Undercuts are generally seen as a defect or imperfection. Welders try to avoid these and repair them when they occur, which result in increased production lead time. Post weld improvement methods i.e. grinding or high-frequency-impact treatment (HFMI) as fatigue-enhancing post-treatment methods enforce amongst other effects a certain smooth undercut-shaped groove in the treated weld toe region. The obtained shallower weld toe transition reduces the geometrical notch effect and increases fatigue strength. This paper presents a study whereas welded specimens with a weld toe geometry similar to what is obtained by weld toe grinding or HFMI-treatment, has been produced, fatigue tested and analyzed. The improvement of the fatigue strength is comparable to post-weld treated specimens. It has proven to be an efficient way to achieve high-quality welds without introducing any additional operations in production, thus enabling weight reduction using cost-effective methods.

  • 721.
    Åström, Hans
    et al.
    University West, Department of Engineering Science, Research Enviroment Production Technology West.
    Stenbacka, Nils
    University West, Department of Engineering Science, Research Environment Production Technology West.
    Hurtig, Kjell
    University West, Department of Engineering Science, Division of Manufacturing Processes.
    Arc Efficiency for Gas Tungsten Arc Welding DCEN-GTAW2013Conference paper (Refereed)
  • 722.
    Öberg, Anna
    et al.
    Volvo.
    Hammersberg, Peter
    Chalmers, Material- och Tillverkningsteknik.
    Svensson, Lars-Erik
    University West, Department of Engineering Science, Division of Production Engineering.
    Selection of Evaluation Methods for New Weld Demands: Pitfalls and Possible Solutions2012In: NDT in Service of Society, in Safety Assurance, Quality Control and Condition Monitoring: The 18th World Conference on Nondestructive Testing, WCNDT-2012 / [ed] M. Johannes, AOSIS, 2012, p. 1-10Conference paper (Refereed)
    Abstract [en]

    New demands often create a need for new evaluation methods. However, there are several pitfalls when choosing those methods that can endanger the expected benefits.

    This study shows examples from the implementation of a new welding standard at several sites in the same company. It focuses on possible pitfalls as well as probable causes and potential solutions with a push- and pull-approach. The examples cover the problems with unclear or too simplified demands, lack of evaluation method and incapable evaluation methods.

    The ability to handle and prevent the described issues is a prerequisite in order to be able to develop the organisation in means of quality assurance for light weight structures.

  • 723.
    Östling, D
    et al.
    Sandvik Teeness AS, Ranheimsveien 127, Trondheim, Norway.
    Magnevall, Martin
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing. Sandvik Coromant AB, Sandviken, Sweden.
    Modelling and characterization of nonlinearities in a tuned mass damper-impulse hammer versus shaker excitation2016In: Proceedings of ISMA 2016 - International Conference on Noise and Vibration Engineering and USD2016 - International Conference on Uncertainty in Structural Dynamics / [ed] Sas P.,Moens D.,van de Walle A., KU Leuven, Departement Werktuigkunde , 2016, p. 3711-3719Conference paper (Refereed)
    Abstract [en]

    The rubber springs of a tuned mass damper (TMD) exhibit both nonlinear stiffness and damping, which complicates measurements of the frequency response function (FRF) of the device. In this paper we model and compare the frequency responses measured with both impulse hammer excitation and a shaker base excitation method. Since the impulse response will spend only a short time in the nonlinear regime, a reasonable assumption is that the nonlinearities will be less apparent and more difficult to determine. The results show that this is not the case and that both methods yield similar nonlinear parameters. By comparing responses at different excitation levels with appropriate nonlinear models, the nonlinearities can be determined. The results indicate that these approximations of the nonlinear effects are able to describe the dynamic behaviour of the TMD, and that the nonlinear properties of the material differ somewhat in the two measurement situations.

12131415 701 - 723 of 723
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