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  • 201.
    Parikh, V. K.
    et al.
    Department of Mechanical Engineering, School of Engineering and Technology, Navrachana University, Vadodara, Gujarat (IND).
    Patel, Vivek
    University West, Department of Engineering Science, Division of Welding Technology.
    Pandya, D. P.
    Department of Mechanical Engineering, School of Engineering and Technology, Navrachana University, Vadodara, Gujarat (IND).
    Andersson, Joel
    University West, Department of Engineering Science, Division of Welding Technology.
    Current status on manufacturing routes to produce metal matrix composites: State-of-the-art2023In: Heliyon, E-ISSN 2405-8440, Vol. 9, no 2, article id e13558Article in journal (Refereed)
    Abstract [en]

    Owing to its excellent properties, Metal Matrix Composites (MMC) has gained popularity and finds application in aerospace, aircraft, shipbuilding, biomedical, biodegradable implant materials and many more. To serve the industrial needs, the manufactured MMC should have homogenous distribution along with minimum agglomeration of reinforcement particles, defect-free microstructure, superior mechanical, tribological and corrosive properties. The techniques implemented to manufacture MMC highly dominate the aforementioned characteristics. According to the physical state of the matrix, the techniques implemented for manufacturing MMC can be classified under two categories i.e. solid state processing and liquid state process. The present article attempts to review the current status of different manufacturing techniques covered under these two categories. The article elaborates on the working principles of state-of-the-art manufacturing techniques, the effect of dominating process parameters and the resulting characteristic of composites. Apart from this, the article does provide data regarding the range of dominating process parameters and resulting mechanical properties of different grades of manufactured MMC. Using this data along with the comparative study, various industries and academicians will be able to select the appropriate techniques for manufacturing MMC.

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  • 202.
    Pejryd, Lars
    et al.
    University West, Department of Technology, Mathematics and Computer Science, Division for Mechanical Engineering.
    Andersson, P.
    Information Back Bone Systems for Virtual Manufacturing, a Comparison of ERP and Engineering Based PLM Systems2006In: 39th CIRP International Seminar on Manufacturing Systems : the morphology of innovative maufacturing systems: Ljubljana, June 7-9, 2006, p. 405-410Conference paper (Other academic)
  • 203.
    Pejryd, Lars
    et al.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing. Örebro University.
    Beno, Tomas
    University West, Department of Engineering Science, Division of Production Engineering. University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Carmignato, Simone
    University of Padova, I 35131 Padova, Italy .
    Computed Tomography as a Tool for Examining Surface Integrity in Drilled Holes in CFRP Composites2014In: Procedia CIRP, ISSN 2212-8271, E-ISSN 2212-8271, Vol. 13, p. 43-48Article in journal (Refereed)
    Abstract [en]

    In light weight structures the joining of composite materials and of composites to metals are key technologies. A manufacturing method associated with joining is the drilling of holes. The hole creation in CRFP through drilling is associated with several defects related to the process, both on the entry and exit sides of the hole and also with dimensional and surface roughness issues of the hole wall. The detection of damage due to the process is not trivial. Especially interesting is non-destructive methods. In this work X-ray computed tomography is used to determine defects due to drilling of holes in a CFRP composite using twist drills with different geometrical features at different drilling parameters. The results can be used to establish relationship between different geometrical features of drills in combination with cutting parameters and resulting surface integrity of holes. © 2014 The Authors. Published by Elsevier B.V.

  • 204.
    Pejryd, Lars
    et al.
    University West, Department of Engineering Science, Research Enviroment Production Technology West.
    Eriksson, Rebecka
    Bofors Test Center,Karlskoga,.
    X-ray Computed Tomography as a Tool in Joining Process Development2014In: Proceedings of the 6th International Swedish Production Symposium 2014 / [ed] Stahre, Johan, Johansson, Björn & Björkman, Mats, 2014, p. 1-7Conference paper (Refereed)
    Abstract [en]

    3-D information on defects in joints are of great importance. Computed tomography is a method that holds the promise of generating this information. This work shows several examples of application of CT on joining or joining related processes. The detection of foreign material, cracks and porosity is shown as well as the ability to investigate much larger volumes than what is feasible with traditional cut-ups. Some limitations are also discussed.

  • 205.
    Pejryd, Lars
    et al.
    University West, Department of Engineering Science.
    Repo, Jari
    University West, Department of Engineering Science.
    Beno, Tomas
    University West, Department of Engineering Science, Division of Production Engineering. University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Machine Tool Internal Encoders as Sensors for the Detection of Tool Wear2012In: Procedia CIRP, ISSN 2212-8271, E-ISSN 2212-8271, Vol. 4, p. 46-51Article in journal (Refereed)
    Abstract [en]

    Tool wear in machining changes the geometry of the cutting edges, which effect the direction and amplitudes of the cutting forcecomponents and the dynamics in the machining process. These changes in the forces and dynamics are picked up by the internalencoders and thus can be used for monitoring of changes in process conditions. This paper presents an approach for the monitoringof a multi-tooth milling process. The method is based on the direct measurement of the output from the position encoders availablein the machine tool and the application of advanced signal analysis methods.

    The paper investigates repeatability of the method developed and how to detect wear in an individual tooth in a milling cutter. Theresults of this work show that various signal features which correlate with tool wear can be extracted from the first few oscillatingcomponents, representing the low-frequency components, of the machine axes velocities. The responses from the position encodersexhibit good repeatability, especially short term repeatability while the long-term repeatability is more unreliable. A worn toothincreases the irregularity in the encoder responses and can be identified at an early stage of the cut.

  • 206.
    Ramasamy, Sudha
    et al.
    University West, Department of Engineering Science, Division of Production Systems.
    Bennulf, Mattias
    University West, Department of Engineering Science, Division of Production Systems.
    Zhang, Xiaoxiao
    University West, Department of Engineering Science, Division of Production Systems.
    Hammar, Samuel
    Graniten, Uddevalla, (SWE).
    Danielsson, Fredrik
    University West, Department of Engineering Science, Division of Production Systems.
    Online Path Planning in a Multi-agent-Controlled Manufacturing System2023In: Lecture Notes in Mechanical Engineering, ISSN 2195-4356, E-ISSN 2195-4364, p. 124-134Article in journal (Refereed)
    Abstract [en]

    In recent years the manufacturing sectors are migrating from mass production to mass customization. To be able to achieve mass customization, manufacturing systems are expected to be more flexible to accommodate the different customizations. The industries which are using the traditional and dedicated manufacturing systems are expensive to realize this transition. One promising approach to achieve flexibility in their production is called Plug & Produce concept which can be realized using multi-agent-based controllers. In multi-agent systems, parts and resources are usually distributed logically, and they communicate with each other and act as autonomous agents to achieve the manufacturing goals. During the manufacturing process, an agent representing a robot can request a path for transportation from one location to another location. To address this transportation facility, this paper presents the result of a futuristic approach for an online path planning algorithm directly implemented as an agent in a multi-agent system. Here, the agent systems can generate collision-free paths automatically and autonomously. The parts and resources can be configured with a multi-agent system in the manufacturing process with minimal human intervention and production downtime, thereby achieving the customization and flexibility in the production process needed. 

  • 207.
    Ramasamy, Sudha
    et al.
    University West, Department of Engineering Science, Division of Production Systems.
    Eriksson, Kristina M.
    University West, Department of Engineering Science, Division of Production Systems.
    Peralippatt, Saptha
    University West, Department of Engineering Science, Division of Production Systems.
    Perumal, Balasubramanian
    University West, Department of Engineering Science, Division of Production Systems.
    Danielsson, Fredrik
    University West, Department of Engineering Science, Division of Production Systems.
    Optimized Online Path Planning Algorithms Considering Energy2021In: Proceedings: 2021 26th IEEE International Conference on Emerging Technologies and Factory Automation (ETFA ), IEEE conference proceedings, 2021, p. 1-08Conference paper (Refereed)
    Abstract [en]

    Plug and produce demonstrators handles multiple processes in the industry, appropriate path planning is essential and at the same time there is an increasing emphasis on more sustainable processes. To ensure the sustainability and automate these processes optimized path planning is required. We present an implementation of a path planning algorithm, which creates a smooth collision free path and considers energy use. In the paper, we demonstrated the implementation of PRM (Probabilistic Road Map) path planning and Dijkstra based optimization algorithm in a simulation environment and thereafter test in a real plug and produce demonstrator. To validate the simulated results the real energy was measured through the signal analyzer online. The measured results outlined in this paper includes; computational time, move along path time, and energy use with different loads. From the experiments and results we conclude that the combination of the two algorithms, PRM with Dijkstra, can be used to generate a collision free optimized path. Here we have considered the distance as the cost function for Dijkstra optimization algorithm and measured the energy of the collision free optimized path. The practical implication of this research is as an enabler for any kind of application where there are large variations of orders e.g., kitting techniques in assembly operations for manufacturing industry.

  • 208.
    Ramasamy, Sudha
    et al.
    University West, Department of Engineering Science, Division of Production Systems.
    Zhang, Xiaoxiao
    University West, Department of Engineering Science, Division of Production Systems.
    Bennulf, Mattias
    University West, Department of Engineering Science, Division of Production Systems.
    Danielsson, Fredrik
    University West, Department of Engineering Science, Division of Production Systems.
    Automated Path Planning for Plug Produce in a Cutting-tool Changing Application2019In: 24th IEEE International Conference on Emerging Technologies and Factory Automation (ETFA), 2019, p. 356-362, article id 8869398Conference paper (Refereed)
    Abstract [en]

    In this paper, a path planning algorithm is designed and tested with a real robot for a Plug & Produce demonstrator. The demonstrator is divided into modules that can be connected and removed. Modules are used for various processes like tool change and storage. This paper focuses on the process of cutting-tool change for the production industry. The Plug & Produce demonstrator uses a multi-agent system where parts and resources are agents. A part agent, e.g., a cutting-tool, can request a robot to perform skills like transportation. This requires the robot to be autonomous. The aim of this paper is to automate the path planning for industrial robotics in a Plug & Produce system. This is done by implementing a sampling based RRT algorithm combined with a collision detection function in RobotStudio. With various real time scenarios, the path planning execution time is observed and presented in the paper.

  • 209.
    Ramesh, Lohith
    University West, Department of Engineering Science.
    Continuous Carbonitriding of bearing rings of material grade SAE521002023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Carbonitriding is an essential heat treatment process in the bearing industry for achieving wear resistance while increasing surface hardness yet keeping the core robust and soft. Any variations in the heat treatment processes have an impact on the mechanical characteristics. Bearing steel grade SAE52100 undergoes carbonitriding heat treatment process in an established batch type furnace at the supplier’s location and then another step of hardening and tempering is performed in house at SKF, Bangalore. Considering the higher volume of carbonitriding bearing material in demand in the future, research was conducted to determine the productivity of carbonitrided rings. The key objective of this project is to investigate the variation in product (inner ring) characterization and compare the similar heat treatment process variables with different types of furnaces by using a continuous type furnace as opposed to an existing batch type furnace, in addition to perform product (bearing ring) characterization of the carbonitrided heat-treated samples of the two furnaces and a productivity comparison of the two furnaces in producing carbonitrided rings. Various characterisation techniques were used to examine heat-treated samples derived from two types of furnaces, namely the continuous type furnace and the seal quenched furnace. These methods included using a Vickers hardness tester to determine hardness levels. In addition, case depth measurement was acquired after 60 minutes of supplementary tempering at 480°C in a muffle furnace. A light optical microscope was also used to examine the carbide-free layers and the uniformity of the carbonitriding layer. For the both the furnace samples, microstructural characterization was performed. Important observations included reduction of process cycle, comparison of production output of the furnaces, hardness values, microstructure ratings and case depth values met the SKF carbonitriding product specification. However, it was observed that in samples from a continuous furnace there were no carbide-free layers at the surface raceway and a non-uniform carbonitriding depth throughout the racetrack, which is detrimental to the material and grinding wheel as the next manufacturing phase is hard machining. In this thesis, preliminary research and product characterization were conducted and analysed, and the results are thoroughly documented. Additional research and testing can be conducted in the future to improve the efficiency of process heat treatment, perform bearing life cycle study, surface residual stress study, and industrialize the process. 

  • 210.
    Rangraz, Masood
    et al.
    University West, School of Business, Economics and IT, Divison of Informatics.
    Pareto, Lena
    University West, School of Business, Economics and IT, Division of Media and Design.
    Robotics and quality: A sociomaterial analysis of assembly line2019In: CEUR Workshop Proceedings, E-ISSN 1613-0073, Vol. 2398, p. 123-136Article in journal (Refereed)
    Abstract [en]

    Automation of manufacturing industry has been on agenda for nearly five decades now. Today, the affordability and efficiency of automated solutions make them increasingly relevant to Small and Medium-size Enterprises (SMEs). Their continued survival depends on the quality of the end product and as much as any SME might intend to increase its business potential, it can’t afford to lose quality by the time it turns to automated solutions. Here, we focus on an assembly line soon to leave its manual processes to automation. It is a case from a manufacturing plant, and we ask what happens to quality once the automation solutions are in place? Exploiting the five notions of Sociomateriality, we explore the changes in the socio-technical configurations of the workplace each of which, we discuss, are consequential for quality. We show while quality is an ultimate business goal for any SME; it is first and foremost a practical problem at the shop-floor. We discuss how quality originates from socio material configurations and distinguish the process-quality from product-quality while attending to working-life quality. We address the challenge of translating the quality which once was in hands, tools, and the relationship among them, to the quality of exact calculations of automated solutions. ©Copyright held by the author(s).

  • 211.
    Rasoulpouraghdam, Arash
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Electron Beam Melting of Alloy 718: Influence of post-treatment on the microstructure and mechanical properties2019Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Additive manufacturing or 3D printing offers the chance to create complex 3D geometries for specific goals in aerospace, energy, automotive, and medical applications. This type of printing enables the manufacturing of elements that are either economically unfeasible or difficult to manufacture through the usual processes, along with low material waste and decreased tooling requirements. Despite these advantages, the mechanical characteristics of fabricated components remain challenging due to the anisotropic behavior of AM specific microstructure.

    The objectives of this thesis were to investigate the microstructure of Alloy 718 manufactured through electron beam melting (EBM), under both as-built and post-treated conditions. In this study, samples were subjected to hot isostatic pressing (HIP) and HIP + solution treatment aging (STA) post-treatments. All samples were produced in the vertical direction in rectangular solid geometry. The studies involved grain width measurements, phases, and defects present, and their respective distribution, also microhardness tests.

    The result demonstrates that microstructures were affected by the thermal history, especially concerning temperature and cooling rates. The HIP treatment results in a considerable decrease in the defects amount and dissolution of γ" phase. Consequently, a reduction in hardness for the HIP condition was observed. Furthermore, post-treatments did not affect the inclusions and NbC because of their high solvus temperature. For HIP+STA treatment, a slight rise in hardness value was recorded compared with the as-built condition, which is attributed to re-precipitation of γ" during the two-step aging process whereas grain width remains steady for all conditions in the hatch region.

  • 212.
    Renugopal, Rajalakshmi
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Design, Analysis and Improvement ofCopper Indium Gallium Selenium ThinFilm Solar Arrays Using SCAPS-1D Simulation Software2018Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The simulation of high efficiency CIGS, i.e., Copper Indium Gallium Selenide cells is the main objective of this thesis. We used SCAPS software for creating a model and basic analysis of the solar cell configuration. An Efficiency calculation was performed by using a baseline model in the SCAPS1D-software. As a first step, a multi-layer absorber structure was added with a graded Ga concentration with varying absorber layer thickness. With this, the electric field increased internally, thus helping to increase the output voltage of the cell. As second and third steps, the temperature and the bandgap was varied. In the final simulation of the CIGS solar cell, an efficiency of 16.33 % could be achieved. A change in temperature from 300 K to 400 K resulted in a drop of efficiency, while a simulated variation in the bandgap and electron affinity resulted in a CIGS solar cell with an efficiency of 22.87 %.

  • 213.
    Repo, Jari
    University West, Department of Engineering Science, Division of Mechanical Engineering.
    Condition Monitoring in Machining Using Internal Sensor Signals2012Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Condition monitoring of critical machine tool components and machining processes is a key factor to increase the availability of the machine tool and to achieve a more robust machining process. Any failure in the machining process and machine tool components may have negative effects on the final produced part. Instabilities in machining processes also shortens the life time of the cutting edges and the machine tool. The condition monitoring system may utilise information from several sources to facilitate the detection of disturbances in the machining process. To minimise additional complexity to the machining system, internal sensor signals for condition monitoring are used.

    The main contribution from this work is a further understanding of the measured responses from linear and angular position encoders during excitation of the machine tool structure. It is shown that the measured encoder responses contain the operational frequencies and this applies to both active and passive machine axes. The response from an active machine axis however, involves a more complex analysis. The fundamental principles on the extraction of the generated micro-vibrations (translational and torsional vibrations) from the linear and rotary encoders are presented. Various methods for their analysis in time domain, frequency domain and phase space domain are also presented. New extentions to the nonlinear numerical methods in order to facilitate the extraction of features from Poincaré sections are introduced.

    The experimental work shows that encoders are sensitive to small disturbances in the machining process. The possibility to use the proposed measurement method and numerical methods for tool wear detection in a milling operation has therefore been investigated. It is shown that tool wear can be detected and quantified by utilising the signals already available in machine tools.

  • 214.
    Repo, Jari
    University West, Department of Engineering Science, Division of Production Engineering.
    Condition monitoring of machine tools and machining processes using internal sensor signals2010Licentiate thesis, comprehensive summary (Other academic)
  • 215.
    Repo, Jari
    et al.
    University West, Department of Engineering Science, Division of Production Engineering.
    Beno, Tomas
    University West, Department of Engineering Science, Division of Production Engineering. University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Pejryd, Lars
    University West, Department of Engineering Science, Division of Production Engineering.
    Machine tool and process condition monitoring using Poincaré maps2010In: COMA'10, International Conference on Competitive Manufacturing: Stellenbosch, South Africa, 3-5 February 2010, 2010Conference paper (Other academic)
  • 216.
    Repo, Jari
    et al.
    University West, Department of Engineering Science, Division of Production Engineering.
    Beno, Tomas
    University West, Department of Engineering Science, Division of Production Engineering. University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Pejryd, Lars
    University West, Department of Engineering Science, Division of Production Engineering. University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    New Aspects on Condition Monitoring of Machine Tools and Machining Processes2009In: The Swedish Production Symposium (SPS'09): 2-3 dec,  Göteborg, 2009, p. 27-33Conference paper (Other academic)
    Abstract [en]

    A general trend within the manufacturing community and in particular the aerospace industry is that the requirements on the manufacturing of components are subjected to ever tighter tolerances and surface integrity restrictions. In order to fulfil these requirements a lot of effort has been carried out to non destructive testing of the produced part. However, the final objective in the first place must be to assure a robust process. One way to achieve a robust process is to continuously monitor it. This may require additional sensors which increase complexity and adds cost. This paper presents suggestions and experimentally achieved results into the extended use of already existing sensors in the machine tool. The basic idea is to show how these sensors can provide additional information about the machine tool itself and how they can be used for monitoring the process as well as to support maintenance activities. The Poincaré analysis method is applied to the position encoder signals to reveal the underlying dynamics when the machine tool structure is excited with a periodically varying load.

  • 217.
    Repo, Jari
    et al.
    University West, Department of Engineering Science, Division of Mechanical Engineering.
    Pejryd, Lars
    University West, Department of Engineering Science, Division of Mechanical Engineering.
    Beno, Tomas
    University West, Department of Engineering Science, Division of Mechanical Engineering. University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Measurement method for the identification of individual teeth in milling operations2012In: CIRP - Journal of Manufacturing Science and Technology, ISSN 1755-5817, E-ISSN 1878-0016, Vol. 5, no 1, p. 26-32Article in journal (Refereed)
    Abstract [en]

    Internal sensors already available in the machine tools may prove to be an interesting approach to monitor the machining process. Accurate determination of the position of the individual tooth on a milling cutter is important to be able to correlate the measured responses from the machine tool position encoders to the tooth or teeth that may be the cause of the response.

    The aim of the work presented in this paper is to develop a measurement method to identify the individual tooth on a milling cutter by their angular position relative to a specified 0-degree direction. If the lower and upper bounds of the cutting zone are known, together with the actual spindle position and the starting time of the cut, it will be possible to track and identify which teeth are within the cutting zone at a given time in the following off-line analysis of the responses. This may simplify the task of finding potential correlations between the state of individual teeth on the milling cutter with measured responses from various sensors during the milling process. The proposed method is based on a reflectance detector and uses accurate position information provided by the position encoders.

    A validation of the measurement method is also presented which shows that the error of the estimated angular position is approximately +/- 0.15 degrees for the validation setup used in this case.

  • 218.
    Repo, Jari
    et al.
    University West, Department of Engineering Science, Division of Mechanical Engineering and Natural Sciences.
    Wretland, Anders
    GKN Aerospace Engine Systems AB, Trollhättan, Sweden.
    Beno, Tomas
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Tu, Juei-feng
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing. North Carolina State University, Department of Mechanical and Aerospace Engineering, Raleigh, North Carolina, United States.
    Detectability of various machining conditions by using internal encoder signals2016In: The 7th International Swedish Production Symposium, SPS16, Conference Proceedings: 25th – 27th of October 2016, Lund: Swedish Production Academy , 2016, p. 1-7Conference paper (Refereed)
    Abstract [en]

    Automated Tool Condition Monitoring (TCM) often relies on additional sensors sensitive to tool wear to achieve robust machining processes. The need of additional sensors could impede the implementation of tool monitoring systems in industry due to the cost and retrofitting difficulties. This paper has investigated the use of existing position encoder signals to monitor a special face turning process with constant feed per revolution and machining speed. A signal processing method by converting encoder signals into a complex-valued form and a new vibration signature extraction method based on phase function were developed to analyze the encoder signals in the frequency domain. The cumulative spectrum indicated that the spectral energy would shift from the lower to the higher frequency band with increasing cutting load. The embedded vibration signatures extracted from the encoder signals provided additional detectability of the machining condition with distinguishable spectral modes. This paper confirms the sensitivity of the encoder signals and more signatures could be extracted for tool wear detection in the future work.

  • 219.
    Rosenbäck, Ritva
    et al.
    University West, Department of Engineering Science, Division of Production Systems.
    Lantz, Björn
    University West, Department of Engineering Science, Division of Industrial Engineering and Management, Electrical- and Mechanical Engineering. Technology Management and Economics, Chalmers University of Technology, 412 96 Gothenburg (SWE).
    Rosén, Peter
    Department of Business Administration, University of Gothenburg, 405 30 Gothenburg (SWE).
    Hospital Staffing during the COVID-19 Pandemic in Sweden.2022In: Healthcare, E-ISSN 2227-9032, Vol. 10, no 10, article id 2116Article in journal (Refereed)
    Abstract [en]

    Staff management challenges in the healthcare system are inherently different during pandemic conditions than under normal circumstances. Surge capacity must be rapidly increased, particularly in the intensive care units (ICU), to handle the increased pressure, without depleting the rest of the system. In addition, sickness or fatigue among the staff can become a critical issue. This study explores the lessons learned by first- and second-line managers in Sweden with regard to staff management during the COVID-19 pandemic. A mixed-methods approach was used, with preliminary qualitative interview (n = 38) and principal quantitative questionnaire (n = 272) studies, based on principal component and multiple regression analyses. The results revealed that the pandemic created four types of challenges relating to staff management: staff movement within hospitals; addition of external staff; addition of hours for existing staff through overtime and new shift schedules; and avoidance of lost hours due to sickness or fatigue. Furthermore, the effects of these managerial challenges were different in the first wave than in later waves, and they significantly differed between the ICU and other units. Therefore, a greater proactive focus on staff management would be beneficial in future pandemic situations.

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  • 220.
    Roskvist, Jimmy
    et al.
    University West, Department of Engineering Science.
    Rydell, Richard
    University West, Department of Engineering Science.
    Konceptframtagning av inspektionspluggar till flygmotorer2009Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This report describes the results of the project "Concept development of jet engine inspection plugs" carried out in the spring of 2008. The work was done at the department of product definition at the company Volvo Aero in Trollhättan. The objective of the work was to develop concepts for a "Volvo-unique" inspection plug. The work is part of Volvo Aero's focus on proprietary (self-developed) technologies. Inspection plugs can be found on virtually all aircraft engines and gas turbines. They are used during inspections with fiber optics done at regular intervals during engine operation. Since the inspection plugs are screwed in and out many times during the life of an engine, it is important that the handling (the assembly and disassembly) is simple. It is also very important that the plugs are properly fixed in position to prevent them from coming off during operation. The focus of the work was to develop proposals on how the assembly and fixing of plugs could be designed to simplify the handling and have adequate and simple function. The procedure during the work was to first study relevant theory and methods that could be used. Then development was carried out according to the first steps of the systematic design methods. These steps include product specifications, concept generation, evaluation and selection of concepts, and development of selected concept. During the implementation, a number of tools and methods, including QFD, FMEA and decision matrices were used. Out of 14 developed concepts, two were chosen for comparison with a leading rival. Both developed concepts turned out to outscore the competitor and the main difference was the cost of production. One of the concepts was considered to have advantages over the other and was consequently chosen for further development. Geometry, manufacturing, materials, sealing and misalignment were the focus areas of the development. CAD models were made of the various design ideas that were identified and one principal inspection plug was recommended for further development.

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  • 221.
    Ru, Tao
    University West, Department of Engineering Science, Division of Manufacturing Processes.
    Spray Parameters Influence on Suspension Plasma Sprayed Zirconia coatings properties2014Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Thermal barrier coatings (TBCs) are a simple and proven method to protect hot section components. Suspension Plasma Spray (SPS), an emerging process technology to generate TBCs, compared with traditional Atmospheric Plasma Spray APS, can deposit thinner coat-ings with finer microstructure. Operating parameters play an important role in developing certain properties of coating. In this thesis work, power level, gas flow rate, number of spray-ing strokes, spray gun's nozzle size i.e. internal diameter and suspension rate were controlled to produce coatings with different microstructures and porosity levels. According to the ex-perimental results, the power level of plasma gun play an essential role on coating micro-structure, for instance, the density of vertical cracks increased with growing the power level. The number of spraying strokes showed also an impact on coating porosity. However, due to different nozzle sizes i.e. diameter, the same coating property were controlled by different operating parameters. For coatings deposited by small and large nozzles, their coating thick-ness and roughness mainly relied on power level and gas flow rate. In contrary, it seems that the coating roughness was not influenced by the same parameters when it was deposited by medium nozzle. Also, gas flow rate do not have as big as influence on coating thickness

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  • 222.
    Runnemalm, Anna
    University West, Department of Technology, Mathematics and Computer Science, Division for Mechanical Engineering.
    Validering i produktutveckling ur ett industriperspektiv2007In: Svenska Mekanikdagar 2007, Luleå University of Technology , 2007, p. 95-Conference paper (Refereed)
  • 223.
    Runnemalm, Anna
    et al.
    University West, Department of Engineering Science, Division of Automation Systems.
    Ahlberg, Jörgen
    Linköping University.
    Appelgren, Anders
    University West, Department of Engineering Science, Division of Automation Systems.
    Sjökvist, Stefan
    Termisk systemteknik AB.
    Automatic Inspection of Spot Welds by Thermography2014In: Journal of nondestructive evaluation, ISSN 0195-9298, E-ISSN 1573-4862, Vol. 33, no 3, p. 398-406Article in journal (Refereed)
    Abstract [en]

    The interest for thermography as a method for spot weld inspection has increased during the last years since it is a full-field method suitable for automatic inspection. Thermography systems can be developed in different ways, with different physical setups, excitation sources, and image analysis algorithms. In this paper we suggest a single-sided setup of a thermography system using a flash lamp as excitation source. The analysis algorithm aims to find the spatial region in the acquired images corresponding to the successfully welded area, i.e., the nugget size. Experiments show that the system is able to detect spot welds, measure the nugget diameter, and based on the information also separate a spot weld from a stick weld. The system is capable to inspect more than four spot welds per minute, and has potential for an automatic non-destructive system for spot weld inspection. The development opportunities are significant, since the algorithm used in the initial analysis is rather simplified. Moreover, further evaluation of alternative excitation sources can potentially improve the performance.

  • 224.
    Runnemalm, Anna
    et al.
    University West, Department of Engineering Science, Division of Mechanical Engineering.
    Appelgren, Anders
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Evaluation of non-destructive testing methods for automatic quality checking of spot welds2012Report (Other academic)
    Abstract [en]

    Car bodies are today more often made of high strength steel. In high strength steel spot welds are more friable and it is necessary to have higher demands on the inspections of spot welds. Quality control of spot weld can be either destructive or non-destructive. Destructive testing is still the most common method to test spot weld. The non-destructive methods that are investigete in this project are visual inspektion (VT), penetrant testing (PT), eddy current testing (ET), ultrasonic testing (UT), magnetic paticle testing (MT) and X-ray testing (RT). Other NDT methods are acoustic emission (AE), digital sheargraphy and IR-termography (IRT). These methods are investigated with focus on the possibility to detect Lens Diameter, stick welds, expulsions, porosity and cracks. And the possibility to automation of the method with focus on size and weight of the system, protection equipment, contact or contactless, one or two sided, position accuracy, and result in real-time.

    Only tree NDT methods, UT, RT and IRT, can detect all discontinuities that we looking for in RSW. The thermography system has the largest potential to be a NDT system for spot weld in the future, mainly because the method is non-contact, which helps when you have the opportunity to searching on a surface instead of a specific position. The main problem with this method is that there is no software for analysing the results to obtain lens diameter.

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    Evaluation of NDT methods
  • 225.
    Runnemalm, Anna
    et al.
    University West, Department of Engineering Science, Division of Mechanical Engineering.
    Appelgren, Anders
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Ahlberg, Jörgen
    Termisk Systemteknik AB.
    Lundevall, Åsa
    SWEREA IVF.
    Albinsson, Ola
    SWEREA IVF.
    Automated NDT cell for quality checking of spot welds2013Report (Other academic)
    Abstract [en]

    This report is written within Spotlight WP5 financed by the FFI programme within Vinnova.

    Thermography is a non-destructive testing method based on measurement of the heat distribution by an infrared camera. The method is suitable for automatic inspection since it is a full filed and non-contact method.

    A thermography system with an analysis tool developed by Termisk Systemteknik AB is investigated as an inspection method for spot weld. The system is able to detect spot welds, measure the diameter and separate a spot weld from a stick weld. The algorithms used in the analysis are rather simplified and the development opportunities are significant.

    A fully automated NDT-cell for spot weld inspection is presented. The automation includes a six axis industrial robot and communication for handling the information flow. This comprised the identification of the inspected spot weld and the reporting to the overall system as to the operator.

    A failure modes and effects analysis (FMEA) of the automated NDT-cell is accomplished and the most important actions are reported

    A business case for implementing a automated NDT-cell was included in the project. In this business case the most promising quality check concepts for NDT spot weld will be presented and compared with the other identified methods.

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  • 226.
    Runnemalm, Anna
    et al.
    University West, Department of Engineering Science, Division of Automation Systems.
    Broberg, Patrik
    University West, Department of Engineering Science, Division of Automation Systems.
    Surface crack detection using infrared thermography and ultraviolet excitation2014In: 12th International Conference on Quantitative InfraRed Thermography, 2014, p. 1-7Conference paper (Refereed)
    Abstract [en]

    High signal to noise ratio is important within non-destructive testing. To achieve automatic inspection, including automatic evaluation, it is even more important. Infrared thermography is a suitable method for automatic inspection. One drawback with thermography of metallic structures is that due to shiny surfaces the reflectance is high and the signal to noise ratio will be low. This paper presents results from surface crack detection with thermography using ultraviolet excitation. The tested component is a welded Inconel plate with a highly reflective surface. Ultraviolet excitation is shown to be a suitable excitation method and high signal to noise is achieved.

  • 227.
    Runnemalm, Anna
    et al.
    University West, Department of Engineering Science, Division of Mechanical Engineering.
    Broberg, Patrik
    University West, Department of Engineering Science, Division of Mechanical Engineering.
    Appelgren, Anders
    University West, Department of Engineering Science, Division of Automation and Computer Engineering. University West, Department of Engineering Science, Division of Production System.
    Possibilities and Limitations of Automated Non-Destructive Testing of Welds2012In: Proceedings of the 5th International Swedish Production Symposium: 6th-8th of November 2012 Linköping, Sweden / [ed] Mats Björkman, Linköping, 2012, p. 3-9Conference paper (Refereed)
  • 228.
    Runnemalm, Anna
    et al.
    University West, Department of Engineering Science, Division of Automation Systems.
    Broberg, Patrik
    University West, Department of Engineering Science, Division of Automation Systems.
    Henrikson, Per
    GKN Aerospace Engine System, Trollhättan.
    Ultraviolet excitation for thermography inspection of surface cracks in welded joints2014In: Nondestructive Testing and Evaluation, ISSN 1058-9759, E-ISSN 1477-2671, Vol. 29, no 4, p. 332-344Article in journal (Refereed)
    Abstract [en]

    Infrared thermography is a non-contact and full field inspection method which has proven to be suitable for automatic surface crack detection. For automatic analysis of the inspection results, a high signal-to-noise ratio (SNR) is required. In this paper an alternative excitation method, using ultraviolet (UV) illumination, is presented and evaluated. Artificial surface defects, so-called notches, in a titanium plate are detected both in the weld seam and in the heat affected zone. Notches with a size from 80 mm in width and 250 mm in length are detected. The SNR using UV illumination is compared with that using flash lamp excitation. The results show that UV illumination using a mercury lamp is a good alternative as excitation source for thermography when detecting surface cracks. To validate the excitation method, results from real surface cracks are included.

  • 229.
    Runnemalm, Anna
    et al.
    University West, Department of Engineering Science, Division of Automation Systems.
    Liu, Tongwein
    Ericsson, Mikael
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Appelgren, Anders
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Influence of Vibration Induced Disturbances in an Automatic Inspection Cell2013In: Robotics in Smart Manufacturing / [ed] Pedro Neto,António Paulo Moreira, 2013, p. 191-202Conference paper (Refereed)
    Abstract [en]

    In the modern manufacturing industry, quality assurance is important. Over the last few years, the interest in automatic inspection has increased and automatic non-destructive testing (NDT) has been introduced. A general automated inspection cell consists of a mechanized system for scanning and a computer system for automatic analysis of the data. In the manufacturing industry, it is preferable to use industrial robots as the scanning equipment since they offer great flexibility, excellent support organization and the in-house know-how is normally high. Another benefit is that a robot can carry different inspection equipment and an inspection cell can therefore include more than one NDT method. For an automatic analysis, high quality of the resulting data is essential. However, a non-stable condition of the NDT sensor mounted on the robotic arm may influence the results. This paper focuses on the influence of the vibration induced disturbances on the results from an NDT system. Vibration amplitude of a point to point robot movement on the robotic arm is measured. The influence of vibration disturbances on the inspection results are evaluated on the thermal images from a thermography system mounted on a six axis industrial robot. The thermal images taken by the system during the movement and after the stop of the robot are evaluated, and the influence of the vibration in these two situations is considered.

  • 230.
    Sadeghimeresht, Esmaeil
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Corrosion Behavior of HVAF-Sprayed Bi-Layer Coatings2016Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    In a variety of engineering applications, components are subjected to corrosive environment. Protective coatings are essential to improve the functional performances and/or extend the lifetime of the components. Thermal sprayingas a cost-effective coating deposition technique offers high flexibility in coatings' chemistry/morphology/microstructure design. However, the inherent pores formed during spraying limit the use of coatings for corrosion protection. The recently developed supersonic spray method, High-Velocity-Air-Fuel (HVAF), brings significant advantages in terms of cost and coating properties. Although severely reduced, the pores are not completely eliminated even with the HVAF process. In view of the above gap to have a high quality coating, bi-layer coatings have been developed to improve the corrosion resistance of the coatings. In a bi-layer coating, an intermediate layer is deposited on the substrate before spraying the coating. The electrochemical behavior of each layer is important to ensure a good corrosion protection. The corrosion behavior of the layers strongly depends on coating composition and microstructure, which are affected by feedstock material and spraying process. Therefore, the objective of the researchis to explore the relationships between feedstock material, spraying process, microstructure and corrosion behavior of bi-layer coatings. A specific motivationis to understand the corrosion mechanisms of the intermediate layer which forms the basis for developing superior protective coatings. Cr3C2-NiCr top layer and intermediate layers (Fe-, Co- and Ni-based) were sprayed by different thermal spraying processes. Microstructure analysis, as well as various corrosion tests, e.g., electrochemical, salt spray and immersion tests were performed. The results showed a direct link between the corrosion potential (Ecorr) of the intermediate layer and the corrosion mechanisms. It was found that the higher corrosion resistance of Ni-based coatings than Fe- and Co-based coatings was due to higher Ecorr of the coating in the galvanic couple with top layers. Inter-lamellar boundaries and interconnected pores reduced the corrosion resistance of intermediate layers, however a sufficient reservoir of protective scale-forming elements (such as Cr or Al) improved the corrosion behavior.

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  • 231.
    Sadeghimeresht, Esmaeil
    et al.
    University West, Department of Engineering Science, Division of Manufacturing Processes.
    Markocsan, Nicolaie
    University West, Department of Engineering Science, Division of Manufacturing Processes.
    Nylén, Per
    University West, Department of Engineering Science, Division of Production Engineering.
    HVAF thermal spray Fe-based coating: An environmentally acceptable alternative to cobalt-based coating2015Conference paper (Refereed)
    Abstract [en]

    Fe-based coatings were widely used in the corrosive environment of various indus-tries. It was replacing expensive cobalt-based alloys, which face a ban in the future due to serious health and environmental risks. The aim of the present work was to compare low temperature corrosion behavior of some Fe- and Co-based coatings produced by High-Velocity Air Fuel (HVAF) thermal spraying. Polarization and elec-trochemical impedance spectroscopy (EIS) tests were carried out in 3.5 wt.% NaCl solution at 25°C. The microstructures were analyzed using optical microscopy (OM) and scanning electron microscopy (SEM) to characterize the morphologies of both Fe- and Co-based coatings and analyze the exposed products along the surface and cross-section of specimens. The results revealed that the high-chromium Fe-based coating protected the underlying substrate better than Co-based coating.

  • 232.
    Sadeghimeresht, Esmaeil
    et al.
    University West, Department of Engineering Science, Division of Manufacturing Processes.
    Markocsan, Nicolaie
    University West, Department of Engineering Science, Division of Manufacturing Processes.
    Nylén, Per
    University West, Department of Engineering Science, Division of Production Engineering.
    Dizdar, S.
    Höganäs AB, Höganäs.
    Corrosion behavior of high-chromium Fe-based coatings produced by HVAF thermal spraying technique2015Conference paper (Refereed)
    Abstract [en]

    Fe-based coatings with different Cr content were prepared by high-velocity air fuel (HVAF) spraying on the surface of both carbon steel and stainless steel 304L. The corrosion behavior of the coatings were evaluated using polarization and electrochemical impedance spectroscopy (EIS) techniques in 3.5 wt.% NaCl solution. Microstructure of the coatings were evaluated by X-ray diffraction (XRD), optical microscopy (OM), scanning election microscopy (SEM), and Energy-dispersive X-ray spectroscopy (EDS) before and after corrosion testing. The experimental results indicated that Cr strongly increased the corrosion resistance of the coating. Furthermore, having an elemental composition closer to that of the substrate, the coatings showed lower susceptibility to galvanic corrosion, accordingly lower corrosion rate.

  • 233.
    Sandberg, Ulf
    University West, Department of Engineering Science.
    Optimum maintenance using knowledge from a complete product population2012In: Proceedings of the 21st International congress on maintenance and asset management: Maintenance excellence for sustainable development / [ed] Vasić, Branko, Belgrad, 2012, p. 851-857Conference paper (Refereed)
    Abstract [en]

    Company’s today aim towards increased performance and effectiveness in order to stay competitive. Being a part of such development programs, the maintenance function tries to be more precise in their doings and more cost-efficient in order to increase their value contribution. However, as a company only is one of many customers to the various suppliers of systems, machines and equipment being used, the maintenance function will remain a sub optimized small part of the various  product populations. The lack of information and knowledge from the complete product populations hampers development and makes all efforts to optimize maintenance in individual company organizations more or less meaningless. The key to improvement is the ongoing experience and the knowledge developed from use of a whole product population.

    This paper describes how maintenance functions must develop using the knowledge acquired from an as complete product population as possible. The development achievable is described and exemplified and key actors are defined together with estimates of the economic potential that could be realized.

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  • 234.
    Sefton, Martin
    University West, Department of Engineering Science.
    Ständiga förbättringar och praktisk problemlösning: en explorativ studie på Saab Automobile AB2009Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Continuous improvement is one of five principles in General Motors – Global Manufacturing System (GM-GMS). GM-GMS has been used by Saab Automobile AB since 2003 and is a central component for realisation of GM’s vision. Internal audits have discovered problems with one of the tools, practical problem solving (PPS), which needs to be improved. The department manufacturing of press and body (PK) wants to survey the problems and initiate a process of improvement. The purpose of this thesis work is to develop a foundation for future re-designs of the PPS process. Employees have been interviewed and observed in order to explore possible difference theoretical and practical problem solving with PPS. The result of the investigation shows 4 different and interrelated problem categories. 1. Information transfer, PPS hand over to product quality engineers (PQE) department cause problem when general assemblies (GA) are excluded from the improvement work. General assemblies do not get any feedback information from (PQE) about planed countermeasures. 2. Problem solving, team leaders has difficulties with identifying the true problem. Using “five-why” during the analysis work causes problem, since team leaders do not have the knowledge of how to use the tool in a proper way. 3. Documentation of PPS, the content in the PPS-form is a problem according to team leaders. Lack of knowledge and understanding of how to use the PPS-document leads to incomplete and incorrect analysis. 4. Coordination of involved people, support and help are missing from the management and quality engineer according team leaders. PPS from Global Costumer Audit are imposing time stress according to team leaders. Recommendations for further work is to investigate the opportunities with a web based PPS and process to improve information transfer and documentation of PPS. A second recommendation is to train and coach team leaders in problem solving and improve coordination of involved people and skills in problem solving.

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  • 235.
    Shi, Zhanyu
    University West, Department of Engineering Science.
    In-process monitoring in laser cladding2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Laser cladding, also known as Direct Metal Deposition (DMD) and Laser Metal Deposition (LMD), represents an advanced additive manufacturing technique. In this process, layers are deposited onto a substrate using a laser beam as the primary heat source. Previously, the necessity for engineers to work physically within the cladding cell exposed them to hazards like laser radiation and powder inhalation. Therefore, the implementation of a monitoring system is imperative for safety reasons.The applications of laser cladding encompass coating, part repair, rapid prototyping, and tooling. This thesis project is conducted in collaboration with SKF Group, a prominent Swedish multinational specializing in bearings, seals, lubrication systems, and related components.The central objective of this study is to develop an image-based monitoring system tailored for laser cladding in industrial settings. Upon successfully establishing the system, the research endeavors to identify appropriate methods for analyzing spatter, melt pool contours, and layer thickness, followed by the interpretation of the gathered data.To summarize, the study has successfully implemented a monitoring system consisting of coaxial and side cameras, both equipped with LED illumination. The effects of varying illumination such as illumination angle, types of light source and ways of driving the system have been examined through experiments conducted under different setups, and the insights gained have been utilized to refine the system. Furthermore, the study analyzed spatter characteristics, melt pool behavior, and layer thickness. 

  • 236.
    Sikström, Fredrik
    et al.
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Ericsson, Mikael
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Christiansson, Anna-Karin
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Niklasson, Kjell
    University West, Department of Engineering Science, Division of Process and Product Development.
    Tools for simulation based fixture design to reduce deformation in advanced fusion welding2008In: Intelligent Robotics and ApplicationsLecture Notes in Computer Science Volume 5315,  2008: First International Conference, ICIRA 2008 Wuhan, China, October 15-17, 2008 Proceedings, Part II / [ed] Youlun Xioun, Springer, 2008, Vol. 5315 LNAI, no PART 2, p. 398-407Conference paper (Refereed)
    Abstract [en]

    The traditional fusion welding and fixture simulations are performed using advanced finite element simulation tools, commonly used are e.g. MSC.Marc, ANSYS, ABACUS and COMSOL Multiphysics. These simulations are made one at a time and separately due to heavy calculation load for each case. Such an approach does not give a full description of the integrated work piece and fixture behaviour. We propose a strategy to decrease the computational time and solve the problem accurately enough for industrial needs. Focus of the simulation result is on residual deformation. The work piece is a simplified component composed by metal sheets, and rigid and loose clamping was investigated. Simulation results give the size of forces and deformations in the clamped edge. Deformation measurements are performed using 3D-scanning of the work piece after cooling and released from fixture, same situation as in the FE-simulations. The proposed strategy has shown to be useful and is industrially competitive due to reduced engineering manpower, computation time, and need for practical experiments. The strategy is to use full off-line programming where computer aided robotics for weld sequencies is integrated with finite element modelling in order to obtain weld parameters and fixture design.

  • 237.
    Sikström, Fredrik
    et al.
    University West, Department of Technology, Mathematics and Computer Science, Division for Electrical Engineering and Land Surveying.
    Ericsson, Mikael
    University West, Department of Technology, Mathematics and Computer Science, Division for Electrical Engineering and Land Surveying.
    Nylén, Per
    University West, Department of Technology, Mathematics and Computer Science, Division for Mechanical Engineering.
    Christiansson, Anna-Karin
    University West, Department of Engineering Science.
    3D-Scanning for Weld Distortion Measuring2006In: Instrumentation and Measurement Technology Conference, 2006. IMTC 2006. Proceedings of the IEEE, IEEE conference proceedings, 2006, p. 2132-2137Conference paper (Refereed)
    Abstract [en]

    Optical three dimensional scanning for weld distortion measurements have been performed for validation, inspection, general visualization and documentation of a robotized welding process. The planning, preparing and processing of the weld is done in a simulation-based concept where computer aided robotics software simulations are integrated with finite element analysis simulations with the objective to reduce global geometrical deformation during welding. The off-line programmed robot paths were used as an input for finite element calculations of temperature fields and distortion in the work piece. In order to validate the finite element model 3D-scannings have been performed before and after every single welding sequence. This paper describes a validation experiment with non-contact measurements of weld distortion and discusses limitations in optical 3D-scanning techniques used for this purpose

  • 238.
    Sikström, Fredrik
    et al.
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Nilsen, Morgan
    University West, Department of Engineering Science, Division of Automation Systems.
    Eriksson, Ingemar
    GKN Aerospace, Trollhättan, Sweden.
    Optical Methods for In-Process Monitoring of Laser Beam Welding2014In: Proceedings of the 6th International Swedish Production Symposium 2014 / [ed] Stahre, Johan, Johansson, Björn & Björkman, Mats, 2014, p. 1-9Conference paper (Refereed)
    Abstract [en]

    This paper addresses the issue of evaluating and selecting optical sensors to be integrated with a 1μm laser beam welding system. The method used for this evaluation is mainly a survey of relevant research litterature. The result of this work is a matrix showing the different methods and distinct features related to relevant process conditions that can be estimated or detected with respective methods. This evaluation also includes considerations on the required sensor bandwidth in relation to inertia and time constants in the physical process.

  • 239.
    Sikström, Moa
    et al.
    University West, Department of Engineering Science.
    Wisén, Nathalie
    University West, Department of Engineering Science.
    Metodutveckling av virtuella byggnationer på Saab Automobile AB2010Independent thesis Advanced level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Saab is in need of an improved method for construction of virtual buildings that the planner can utilize. By creating a process structure in the existing PLM system, that can communicate and consume data from the product structure that already exists, a lot of work could be saved. Presently, the planner uses a visualization program that is connected only to the product structure. The current method with this visualization software is that the planner builds a process structure for each and every new project gate. This structure cannot easily be updated and therefore a new structure must be created before the new project gate. Thus, the virtual builds become resource inefficient.

    By creating a process structure that easily can be updated, the structure could be reused in new gates and projects. This is consistent with the basic ideas behind using a PLM system. There are several obstacles to master before this will be possible. 

    The conclusions of this study are that in the process structure, the articles should be placed under the stations and operations where they are mounted in the actual factory. There is no universal solution as to how the structure should be, but it should reflect the plant processes. In order for the planner to easily take advantage of this structure, it should also be possible to look up articles using a name filter.

    Planners are currently responsible for particular product areas, such as safety related articles. All parts of this product field are installed in separate sections in the plant. In order to efficiently find all the articles in the process structure, the operations should be named after the articles that are assembled under the specific operation.

    A temporary working method has been proposed and the instructions can be found in Appendix B.

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  • 240.
    Singh, Gurdit
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Effect of Grain Size on the Susceptibility towards Strain Age Cracking in the Precipitation Hardening Nickel-Based Superalloy Haynes® 282®2019Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    With increasing the demand for higher efficiency of aircraft engines, a material which can withstand higher temperature is needed, together with good weldability, creep, and corrosion resistance. Alloy 718 has been the standard grade for several years, it provides high strength at elevated temperature. This alloy has good fabrication capability due to sluggish precipitation kinetics of its hardening phase gamma prime double prime. On the other hand temperature stability can be increased by using superalloys that are precipitation hardened by the gamma prime phase.

    Haynes 282 is newly developed gamma prime precipitation hardening superalloy, which has 150°C higher temperature stability than Alloy 718. Rapid hardening of gamma prime phase can increase the susceptibility toward stain age cracking (SAC). This cracking phenomenon occurs during post weld heat treatment when residual stress relaxation coincides with the precipitation of hardening phases. Apart from rapid precipitation kinetics other factors also influence SAC resistance such as chemical composition, Al+Ti content, microstructure and grain size.

    This work sets focus on grain size effects on SAC susceptibility in Haynes 282. Large grain size was found to have a positive effect on ductility when compared to mill annealed material.

  • 241.
    Singh Handa, Sukhdeep
    University West, Department of Engineering Science, Division of Manufacturing Processes.
    Precipitation of Carbides in a Ni-based Superalloy2014Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Alloy B is relatively new precipitation hardening superalloy. It´s applications are in the hot sections of the aero engines, rocket nozzles, gas turbines and in the chemical and petro-leum applications. The alloy is characterized by keeping high strength at elevated tempera-tures and high creep resistance. It´s excellent mechanical properties and corrosion resis-tance are due to the balanced amount of the coherent γ' matrix, combined with other alloy-ing elements and carbides.

    There are three types of carbides which can be found in nickel-based superalloys: MC, M

    23C6 and M6C. Primary MC carbides act as source of carbon for the secondary carbides, which precipitate at the grain boundaries. They can have strengthening effect by hindering the movement of dislocations.

    In this work both simulation and experimental analysis are conducted in order to investi-gate the behaviour of the secondary carbides. JMatPro simulation is used to predict the behaviour of the material. Heat treatments are conducted at soak temperatures ranging from 920 °C to 1130 °C, with steps of 30 °C, and dwell times of 0.5, 1, 2 and 24 hours. Experimental methods included analysis at LOM, SEM, EDS, manual point counting and hardness tests.

    Main results show chromium rich M

    23C6 carbides are stable at lower temperature compared to molybdenum rich M6C. Both appear as fine and discrete particles at the grain boundaries at 1070 °C. This morphology is believed to be beneficial for the mechanical properties of the alloy. The volume fraction varies between 0.6 and 1.3%. Hardness values are relevant in the range of 920-1010 °C. Above this range there is sudden drop of the hardness

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  • 242.
    Sjöstedt, Jacob
    et al.
    University West, Department of Engineering Science, Division of Mechanical Engineering and Natural Sciences.
    Magnusson, Daniel
    University West, Department of Engineering Science, Division of Mechanical Engineering and Natural Sciences.
    Konceptutveckling av ljud- och vibrationsreducering för scrollkompressor i en elektrisk bil2016Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Detta examensarbete har utförts under tio veckor på ÅF Automotive i Trollhättan med syftet att reducera det hörbara ljudet för passagerarna i en elektrisk bil. Huvudproblemet är att kompressorn i klimatanläggningen genererar luftburet ljud och vibrationer vilket leder till en försämrad komfort för passagerarna. ÅF Automotive ska köpa in en ny kompressor och önskar en kravspecifikation innehållande ljudkällorna i en scrollkompressor samt riktlinjer för hur effekterna från dessa kan reduceras. Denna kravspecifikation ska senare användas som beslutsunderlag till förhandlingen. Koncept i form av komplement till scrollkompressorn ska utvecklas som reducerar luftburet ljud och vibrationer från varje identifierad ljudkälla.För att genomföra arbetet på ett systematiskt sätt har metoder och verktyg lämpade för konceptutveckling använts. Ljudkällorna i scrollkompressorn identifierades genom att utföra observationer, intervjuer och litteraturstudier. En kravspecifikation på de identifierade ljudkällorna upprättades därefter. Genom att tillämpa en generisk produktutvecklingsprocess utvecklades flera koncept för att reducera ljud och vibrationer från de identifierade ljudkällorna. För att finna de bästa koncepten utfördes konceptval innefattande multiröstning,beslutsmatriser och mer djupgående analyser vilka behandlar risk för patentintrång, miljöpåverkan, ljudreduceringsförmåga, monterbarhet, säkerhet samt kostnad. Fyra koncept; fjädrar, gummibussningar, hårt skal och mjukt skal valdes då de reducerar ljudet i passagerarutrymmet och presterade väl under den djupgående analysen och är därför värda att vidareutveckla. Hur mycket ljud de kommer att reducera har inte specificerats. Detär nu upp till ÅF Automotive att göra ett val över vilka koncept som de vill vidareutveckla. Koncepten är fortfarande på en generell nivå och måste anpassas specifikt till den scrollkompressor som väljs att köpas in. Koncepten har endast utvecklats för att reducera ljud och vibrationer och det finns fortfarande osäkerheter som kommer behöva behandlas i framtiden.

  • 243.
    Steffenburg-Nordenström, Joachim
    et al.
    University West, Department of Engineering Science, Research Enviroment Production Technology West.
    Svensson, Lars-Erik
    University West, Department of Engineering Science, Division of Welding Technology.
    Simulation and Validation of Forming, Milling, Welding and Heat Treatmentof an Alloy 718 Component2017In: International Journal of Materials Forming and Machining Processes IJMFMP), ISSN 2334-4563, Vol. 4, no 2, p. 15-28Article in journal (Refereed)
    Abstract [en]

    This paper describes finite element simulations of a manufacturing process chain consisting of

    forming, weld preparation by milling, laser welding and stress relief heat treatment of an alloy 718

    aero-engine part. The work also includes experimental validation with optical measurements of the

    part after each process step. Approximation and discretization errors were avoided by keeping the

    same mesh and constitutive model. The results show that the remaining stresses affect the subsequent

    manufacturing process step and therefore, simulation of the process chain is essential. The accuracy

    with respect to the geometry showed relatively good agreement between measurement and simulation.

  • 244. Sudarshan, T.S.
    et al.
    Nylen, PerUniversity West, Department of Engineering Science, Division of Production Engineering.
    Surface Modification Technologies XXII: Proceedings of the Twenty Second International Conference on Surface Modification Technologies  Held at University West, Trollhättan, Sweden September 22-24, 20082009Conference proceedings (editor) (Other academic)
  • 245.
    Svensson, Bo
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Optimisation of Manufacturing Systems Using Time Synchronised Simulation2010Licentiate thesis, comprehensive summary (Other academic)
    Download full text (pdf)
    FULLTEXT01
  • 246.
    Svensson, Bo
    et al.
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Danielsson, Fredrik
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Off-Line Parameter Tuning of a Sheet-Metal Press Line2011In: The 4th International Swedish Production Symposium, Lund: Swedish Production Academy , 2011, p. 459-466Conference paper (Refereed)
    Abstract [en]

    Anautomotive sheet-metal press line is an excellent example of an automatedmanufacturing system with time dependent complex control functions. The PLCcontrol functions include not only discrete events and supervisory control, butalso analogue feedback and motion control. Furthermore, most press line tuningmethods today are on-line and highly empirical, depending on individualoperators. Thus, there is a need of an objective off-line parameter tuningmethod. This paper presents an off-line parameter tuning of an automotivesheet-metal press line. Improved production performances have been reached,both in terms of increased production rate and smoother robot motions, comparedto today’s industrial on-line method. Two suitable optimisation algorithms havebeen implemented and evaluated. The challenge is to handle highly non-linearfunctions, considerable number of parameters, and long evaluation times in thesimulation. The utilised off-line method is a combination of simulation basedoptimisation and time synchronised hardware-in-the-loop simulation, i.e. avirtual manufacturing system including real PLCs. This method provides adistinct advantage, since it describes all complex control functions byexecuting the same PLC control code used in the manufacturing plant. A furtherbenefit is that all tuned process parameters can be directly transferred to themanufacturing plant.

  • 247.
    Svensson, Bo
    et al.
    University West, Department of Engineering Science, Division of Automation Systems.
    Danielsson, Fredrik
    University West, Department of Engineering Science, Division of Automation Systems.
    P-SOP -€“ A multi-agent based control approach for flexible and robust manufacturing2015In: Robotics and Computer-Integrated Manufacturing, ISSN 0736-5845, E-ISSN 1879-2537, Vol. 36, p. 109-118, article id 1301Article in journal (Refereed)
    Abstract [en]

    In a truly flexible manufacturing system the description of the control strategy must be updated every day. Hence, a new way to handle changes in the environment down to control system deployment and production is required. This paper presents a novel approach, based on P-SOP, to handle multi-agent based control and verification. The P-SOP approach addresses flexibility, robustness and deployment in the best possible manner with the least waste of time and effort. P-SOP includes a description language where the control strategy based on actual circumstances easily can be defined. Based on the description multi-agents, to control the manufacturing, are automatically generated. An industrial advantage is that the multi-agent generator creates IEC 61131-3 PLC code that can be executed on standard PLC’s. This feature eliminates the need for experts in PLC programming and reduce deployment time to become more efficient. Hence, this flexibility enables small series down to one off production in a competitive way. With multi-agent control it is also possible to handle rebalancing due to market changes, scheduling of available humans, introduction of new part types, and rerouting due to a machine break down or planned service. The generated agents are not optimised for a final solution with specific timings. All decisions are made on-line and the generated solution adapts to the circumstances that arise. With the P-SOP multi-agents it is easy to manually remove or introduce parts to the manufacturing cell without disturbing the system, e.g. for manually random inspections, removal of parts due to restart. The formulated description language and the multi-agent generator has been successfully tested and evaluated in an industrial environment.

  • 248.
    Svensson, Bo
    et al.
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Danielsson, Fredrik
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Lennartson, Bengt
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    A Virtual Real-Time Model for Control Software Development: applied on a Sheet-Metal Press Line2005In: Industrial Simulation Conference 2005 / [ed] Jörg Kruger, Alexei Lisounkin, Gerhard Schreck, 2005, p. 119-123Conference paper (Refereed)
  • 249.
    Svensson, Bo
    et al.
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Danielsson, Fredrik
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Lennartson, Bengt
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering. University West, Department of Engineering Science, Division of Production Systems.
    Off-Line Optimisation of Complex Automated Production Lines: Applied on a Sheet-Metal Press Line2007In: Proceedings of the 2007 IEEE International Symposium on Assembly and Manufacturing, IEEE , 2007, p. 82-87Conference paper (Refereed)
    Abstract [en]

    This paper presents a successful off-line

    optimisation case study of a sheet-metal press line for the

    automotive industry. The proposed off-line optimisation

    method results not only in increased production rate but also in

    obtaining smoother material handling motions. The off-line

    optimisation method contains two parts. The first part is a

    parameter study, combining factorial design with production

    line simulation including emulated control systems and

    resulting in a simplified performance model based on multiple

    linear regression. The second part is an optimisation on the

    simplified performance model using the Nelder Mead simplex

    method aiming at production optimisation. Due to the

    complexity in a modern production line, it is not possible to

    create a useful model representation of the entire control

    system code/function. Therefore, the proposed optimisation

    method is based on using production line simulation including

    emulated control systems with the real IEC 61131-3 control

    code. Our approach in this work is a parameter variation

    strategy for optimisation, i.e. adjusting the control system

    parameters in the same way as the line operators do, and not

    changing any control strategy.

  • 250.
    Svensson, Bo
    et al.
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Danielsson, Fredrik
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Lennartson, Bengt
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering. University West, Department of Engineering Science, Division of Production Systems.
    Time-synchronised hardware-in-the-loop simulation - Applied to sheet-metal press optimisation2012In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 20, no 8, p. 792-804Article in journal (Refereed)
    Abstract [en]

    This paper presents an off-line process parameter tuning method, focussing on complex control functions for automated manufacturing systems. The proposed method is based on a combination of simulation-based optimisation and time-synchronised hardware-in-the-loop simulation. Real indus- trial control systems, e.g., PLCs, are included in the simulation, executing the unchanged control code from the manufacturing plant. This approach allows all plant control functions to be included, even time-critical feedback loops and vendor secret blocks such as motion control. Consequently, the method suggested manages the problems identified in previously presented simulation-based approaches. Furthermore, a case study of an automotive sheet-metal press line has been performed to verify the proposed method, with successful results.

23456 201 - 250 of 270
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