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  • 1.
    Abdo, Nawar
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Modularization and evaluation of vehicle’s electrical system2019Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Modularisering är en strategi som används av många företag, för att hjälpa dem att erbjuda sina kunder en mängd olika anpassade produkter på ett effektivt sätt. Detta görs genom anpassning av olika oberoende moduler, som är kopplade med standardiserade gränssnitt som utnyttjas av alla modulvarianterna. Scania, som är ett av de stora företagen som erbjuder modulariserade produkter, har framgångsrikt förbättrat sina modulariseringskoncept under många år och är ett av de mest ikoniska företagen närdet gäller modularisering av bussar, lastbilar och motorer. Men med det ökande behovet av elektronik integrerad i fordonen blir det allt viktigare att modularisera det elektriska systemet.

    Det finns för närvarande en befintlig, modulär produktarkitektur för det elektriska systemet, och Scania vill veta hur väl modulariserat det är, eftersom det inte finns något enat sätt som anger vad som anses vara den bättre lösningen. För att analysera det elektriska systemets nuvarande tillstånd, måste en systematisk metod förmodularisering användas, vilket skulle hjälpa till att svara på tre viktiga frågor: Är modulerna väldefinierade? Finns det ett sätt att systematiskt jämföra alternativa lösningar? Vilka kriterier är viktigare att fokusera på?

    Eftersom det inte finns något enhetligt sätt att modularisera har många modulariseringsmetoder skapats, och var och en har optimerats för ett visst ändamål. I projektet jämförs tre olika modulariseringsmetoder och använder sedan en av de metoder som anses vara den föredragna metoden för att hjälpa till att ge svaren som företaget söker när man undersöker modulariteten hos det elektriska systemet.

    Eftersom det elektriska systemet är väldigt komplext och projektet har begränsat antal resurser beslutades det att välja en av kontrollenheterna som ett exempel, vilket var APS (luftbehandlingssystem). Litteraturstudien visade att den mest givande metoden att använda var MFD (Module FunctionDeployment), eftersom det ger mer information om produkten och vilka kriterier företaget ska fokusera på. Det bestämdes sedan att använda de relevanta stegen i MFD för att analysera APS tillståndet som ett exempel på hur den här metoden fungerar.

  • 2.
    Adamsson, Niklas
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Interdisciplinary integration in complex product development: managerial implications of embedding software in manufactured goods2007Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Incorporating electronics and software systems into manufactured goods is becoming very common in manufacturing companies. New technical functions, increased flexibility, and compensation for mechanical design weaknesses are some key drivers of this technological change in our everyday products. The automotive industry exemplifies this trend, since approximately 80–90% of new functions in cars are based on electronics and software, and it is expected that at least a third of the total cost of a car will eventually be accounted for by electronics and software. However, one of the main downsides of this technological trend is the increasing number of quality issues related to these new technologies, something usually claimed to be a result of the increased product development complexity.

    Previous research into product development management has mainly concentrated on either physical products or software systems, but not concurrently on both. Additionally, much of the research has concentrated on issues of integrating marketing, R&D, and manufacturing in these companies, and has treated the engineering disciplines in R&D as a homogenous group. Motivated by this change in technology content and the lack of research into complex product development and especially into integration between engineering disciplines, the present work investigates how to increase operational performance in multidisciplinary engineering organizations. This work has especially focused on interdisciplinary integration and the feasibility of various so-called integration mechanisms, such as building common physical facilities, job rotation programs, the implementation and use of information and communications technology, and computer-aided engineering tools.

    Both qualitative and quantitative research has been performed, involving 11 different companies and over 300 respondents. Supported by the present findings, it is demonstrated that interdisciplinary integration is a crucial factor to consider, and it is concluded that certain integration mechanisms stand out as more important than others. Organizational structure, work procedures and methods, training, social systems, and computer-aided engineering were the five types of mechanisms that displayed the greatest potential for improvement.

    It is further concluded that the ability to successfully match the body of practices to current products is essential, since there is a high risk of current practices becoming out-dated with respect to the technology content. Furthermore, inadequate identification of or managerial ability to establish the currently most important interfaces complicate the choice of trade-offs between various technologies that are found to be essential to cope with the inherent dynamic complexity. The organizational powerbase is often re-positioned in the studied organizations, and the loss of decisive power can result in a demoralizing ignorance of newly established disciplines and their design practices. Additionally, rigid structures and counterproductive traditions can reduce the potential gains accruing from new boundary-spanning innovations, so organizational responsibilities and mandates must be declared unambiguously, in many cases differently from how they have been in the past.

    Based on these conclusions, it is suggested that managers in organizations like those studied must be able to do the following: cultivate software knowledge in all parts and levels of the product development organization; reassess their recruitment strategies; organize for interdisciplinary collaboration; articulate and communicate the technology fusion strategy to all disciplines; and realize and disseminate the fact that product launches do not only concern manufacturability.

  • 3.
    Adamsson, Niklas
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Management of mechatronics engineering: reflections and propositions2005Ingår i: Proceedings of 12th International Product Development ManagementConference, vol. 1, 2005, Vol. 1(3), s. 35-48Konferensbidrag (Refereegranskat)
  • 4.
    Adamsson, Niklas
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Mechatronics engineering: New requirements on cross-functional integration2005Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Several industrial sectors experience an increased reliance on mechatronic systems as electronics and software are being embedded into the traditional mechanical systems of these industries. Important challenges within mechatronics engineering comes from management of multi-disciplinary development project teams and the highly complex scope of problems, which in turn require extensive coordination and integration, both in terms of technical and organisational matters.

    The concept of cross-functional integration in product development research has in previous research mainly addressed integration of the functions marketing, R&D, and manufacturing, and whereas the present thesis is delimited to include only the R&D organization and the functions and engineering disciplines within such an organization.

    The purpose with thesis has been to investigate mechatronics engineering in order to understand and explain how co-operation, integration, and knowledge sharing between engineering disciplines can be supported.

    This research has been realized by empirical studies in mechatronic development settings in engineering companies, but also by taking part in industrial and academic research projects that develop and study computer-aided mechatronics engineering.

    Findings presented in this thesis show that mechatronics is a matter of integration at three organizational levels where the most substantial needs are found to be at the team-level and the individual level. Furthermore, it is identified that to be able to succeed in mechatronics engineering, managers and engineers must look beyond disciplinary needs. Subsequently, both teamwork and competence management become key issues for management of mechatronics engineering. Finally, computer-supported and model-based development of mechatronics show great potential for successful integration of engineering disciplines, even though such technological aids are still rather immature and needs further research and development. A tentative analysis model of organizational integration for mechatronics engineering is also presented and discussed in this thesis.

    Based on the presented findings, it is concluded that companies incorporating electronics and software in their mechanical products must effectively manage software and electronics development of these embedded systems. Despite the focus on cross-functional integration in engineering companies, this thesis shows examples of inadequate integration of software and electronics engineering with mechanical integration in organisations dominated by the latter.

    Future research studies are needed to investigate the relation between factors influencing the need for organizational integration and potential integration mechanisms. To further understand mechatronics engineering it is important to look deeper into research issues such as changed conditions for the engineering profession implied by multidisciplinary settings, social systems supporting integration of disciplines, changed work conditions due to implementation of technological aids for model-based system development, relationship between product and organizational complexity, organizational designs supporting integration of engineering disciplines, and cross-disciplinary training of highly specialized engineers.

  • 5.
    Adamsson, Niklas
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Malvius, Diana
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Formal and informal roles in complex product development2005Ingår i: 2005 IEEE International Engineering Management Conference, Vols 1 and 2, 2005, s. 559-563Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper illustrates the importance of well-articulated and demarcated roles in complex product development settings. In order to support interdisciplinary knowledge and information sharing formally assigned roles in an organization can be an effective facilitator. It is argued that without comprehensive technical knowledge it is difficult for individuals to identify the relevance and distinctiveness of technical and administrative information.

  • 6.
    Adamsson, Niklas
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Zika-Viktorsson, Annika
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.).
    Challenges and outlooks for software and electrical engineering in traditional mechanical engineering companies: an investigation into workforce implications2006Artikel i tidskrift (Övrigt vetenskapligt)
  • 7.
    Adamsson, Niklas
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Zika-Viktorsson, Annika
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Multidisciplinary product development: - a case study of mechatronics enineeringArtikel i tidskrift (Övrigt vetenskapligt)
  • 8.
    Adamsson, Niklas
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Zika-Viktorsson, Annika
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.).
    The relative effectiveness of different mechanisms for integrating engineering disciplines in complex product development2007Artikel i tidskrift (Övrigt vetenskapligt)
  • 9.
    Adamsson, Niklas
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Zika-Viktorsson, Annika
    Understanding the importance of interdisciplinary integration in complex product development2007Rapport (Övrigt vetenskapligt)
  • 10.
    Afsharian, Reza
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Theodoropoulos, Antonios
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Modular friction test rig for measuring torque and tension in threaded fasteners2018Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Denna rapport beskriver utvecklingen av en modulär friktionsprovrigg för gängade fästelement. Den utvecklade enheten kan mäta moment och klämkraft under åtdragning av gängade skruvar, med en storlek mellan M3 och M14 och klämlängd på 30-160mm. Designen möjliggör användning av flera last- och vridmomentceller och intervallet är upp till 100kN klämbelastning och 200Nm påfört vridmoment. Provriggen är en forskningsrigg, och den kommer att användas av Atlas Copco för att bestämma friktionsegenskaperna i åtdragning och möjliggöra experiment på skruvar av olika material, och med olika ytbeläggningar och ytbehandlingar. Denna rapport avslutas med ett designförslag, som utvärderas analytiskt och testprincipen demonstreras med hjälp av en prototyp. Mätningarna tas från skräddarsydda sensorer, som kan kalibreras individuellt och som är enkelt utbytbara. Dessutom är en anordning utvecklad för att tillåta användaren att ändra styvheten hos förbandet. Slutligen ges en rekommendation för en vidareutveckling, som möjliggör mätning av skallmomentet. Detta förslag är ett genombrott jämfört med andra existerande testriggar, och kommer att bidra till att verifiera friktionsmätningarna med hög precision.

  • 11.
    Aftab, Ahmad
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Mekatronik.
    Andersson, Kjell
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Sellgren, Ulf
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Khan, Suleman
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Mekatronik.
    A stiffness modeling methodology for simulation-driven design of haptic devices2014Ingår i: Engineering with Computers, ISSN 0177-0667, E-ISSN 1435-5663, Vol. 30, nr 1, s. 125-141Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Efficient development and engineering of high performing interactive devices, such as haptic robots for surgical training benefits from model-based and simulation-driven design. The complexity of the design space and the multi-domain and multi-physics character of the behavior of such a product ask for a systematic methodology for creating and validating compact and computationally efficient simulation models to be used in the design process. Modeling the quasi-static stiffness is an important first step before optimizing the mechanical structure, engineering the control system, and performing hardware in the loop tests. The stiffness depends not only on the stiffness of the links, but also on the contact stiffness in each joint. A fine-granular Finite element method (FEM) model, which is the most straightforward approach, cannot, due to the model size and simulation complexity, efficiently be used to address such tasks. In this work, a new methodology for creating an analytical and compact model of the quasi-static stiffness of a haptic device is proposed, which considers the stiffness of actuation systems, flexible links and passive joints. For the modeling of passive joints, a hertzian contact model is introduced for both spherical and universal joints, and a simply supported beam model for universal joints. The validation process is presented as a systematic guideline to evaluate the stiffness parameters both using parametric FEM modeling and physical experiments. Preloading has been used to consider the clearances and possible assembling errors during manufacturing. A modified JP Merlet kinematic structure is used to exemplify the modeling and validation methodology.

  • 12.
    Aftab, Ahmad
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Mekatronik.
    Khan, Suleman
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Mekatronik.
    Andersson, Kjell
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Kinematics and Dynamics of a novel 6-DoF TAU Haptic Device2011Ingår i: Proceedings of the 2011 IEEE International Conference on MechatronicsInternational Conference on Mechatronics, April 13-15, 2011, Istanbul, Turkey, IEEE conference proceedings, 2011, s. 719-724Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents the kinematics and dynamics modeling of a novel hybrid kinematic concept, i.e. the TAU haptic device. This new concept was obtained from the modification of TAU-2 structure proposed by Khan et al. First a kinematic model for inverse and forward kinematics was developed and analyzed. Then an algorithm to solve the close form inverse dynamics is presented using Lagrangian formulation. Numerical simulation was carried out to examine the validity of the approach and accuracy of the technique employed. A trigonometric helical trajectory of 5th order spline was developed in Cartesian space for each degree of freedom of the moving platform in order to verify and simulate the inverse dynamics; the motion of the platform is such that the tool centre point remains on this trajectory while its orientation is changing constantly in roll, pitch and yaw.

  • 13.
    Agrell, Fredrik
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Control of HCCI by aid of Variable Valve Timings with Specialization in Usage of a Non-Linear Quasi-Static Compensation2006Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This doctoral thesis is about controlling the combustion timing of the combustion concept Homogeneous Charge Compression Ignition, HCCI, by means of variable valve timings.

    The HCCI research usually is regarded to have started in Japan during the later part of the 1970´s. The world of HCCI has since grown and HCCI is of today researched worldwide. Of particular interest from a Swedish point of view is that Lund Institute of Technology has emerged as one of the world leading HCCI laboratories.

    The idea with HCCI is to combine the Otto and Diesel engine. As in an Otto engine the charge is premixed but as in a Diesel engine the operation is unthrottled and the compression heat causes the ignition. The combustion that follows the ignition takes place homogeneously and overall lean. The result is ultra low NOx and particulate emissions combined with high total efficiency. A difficulty with the HCCI-concept is that it only works in a narrow area and that there is no direct way to control the Start Of Combustion, SOC. Out of this follows that timing/phasing of the combustion is one of the main difficulties with HCCI combustion concepts. This is particularly emphasized during transient operation and calls for feedback control of the combustion timing.

    This work investigates one method, the variable valve timing, to achieve feedback control of the combustion phasing. From the work it can be concluded that the variable valve timing can control the combustion phasing during engine transients. In order to improve the performance a non-linear compensation from ignition delay to valve timings has been suggested, incorporated in a control structure and tested in engine test. The engine test has been performed in a single cylinder engine based on a Scania truck engine. The speed range from 500 to 1750 rpm and the load range 1.26 and 10.5 bar of netIMEP has been covered with fair transient performance.

  • 14.
    Agrell, Fredrik
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Ångström, Hans-Erik
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Eriksson, Bengt
    Wikander, Jan
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Linderyd, Johan
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Control of HCCI During Engine Transients by aid of Variable Valve Timings Through the use of Model Based Non-Linear Compensation2005Ingår i: SAE transactions, ISSN 0096-736X, Vol. 114, nr 3, s. 296-310Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    One of the main challenges with the Homogeneous Charge Compression Ignition, HCCI, combustion system is to control the Start Of Combustion, SOC, for varying load and external conditions. A method to achieve this on a cycle-by-cycle basis is to vary the valve timing based on a feedback signal from the SOC of previous cycles. The control can be achieved with two basic valve-timing strategies named the Overlap- and the IVC-method. The Overlap-method works by trapping of residuals while the IVC-method affects the effective compression ratio. In an earlier paper it has been shown that if the two methods are incorporated into one controller, SOC can be controlled in a relatively large operating window although the transient performance was not sufficient. The reason is that the simple PI-controller cannot be made fast enough to cope with the transients without magnifying the cycle-to-cycle variations of the combustion into instability. In this work a model based control system that features a non-linear compensation, based on the inverse of the non-linear function from valve timings to ignition delay, is suggested and evaluated. The results show good transient performance. Control performance from engine tests is reported. A combined engine and control simulation system is used for the development of the control strategies. The simulations are accomplished with a commercial cycle simulation code linked with a commercial control simulation code. The simulations are iteratively verified against engine test data. Engine tests are conducted on a single cylinder engine equipped with a hydraulic valve system.

  • 15.
    Agrell, Fredrik
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Ångström, Hans-Erik
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Eriksson, Bengt
    Wikander, Jan
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Linderyd, Johan
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Practical Modeling of HCCI for Combustion Timing Control and Results from Engine Test2005Ingår i: KTH Internal Combustion Engine Report MFM, Vol. 162Artikel, forskningsöversikt (Refereegranskat)
  • 16.
    Agrell, Fredrik
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Ångström, Hans-Erik
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Eriksson, Bengt
    Wikander, Jan
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Linderyd, Johan
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Transient Control of HCCI Combustion by aid of Variable Valve Timing Through the use of a Engine State Corrected CA50-Controller Combined with an In-Cylinder State Estimator Estimating Lambda2005Konferensbidrag (Refereegranskat)
    Abstract [en]

    One of the main challenges with the Homogeneous Charge Compression Ignition, HCCI, combustion system is to control the Start Of Combustion, SOC, for varying load and external conditions. A method to achieve this on a cycle-by-cycle basis is to vary the valve timing based on a feedback signal from the SOC of previous cycles. The control can be achieved with two basic valve-timing strategies named the Overlap- and the IVC-method. The Overlap-method works by trapping of residuals while the IVC-method affects the effective compression ratio

  • 17.
    Ahmad, Aftab
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Effective development of haptic devices using a model-based and simulation-driven design approach2014Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Virtual reality (VR)-based surgical simulators using haptic devices can increase the effectiveness of surgical training for surgeons when performing surgical procedures in hard tissues such as bones or teeth milling. The realism of virtual surgery through a surgical simulator depends largely on the precision and reliability of the haptic device, which reflects the interaction with the virtual model. The quality of perceptiveness (sensation, force/torque) depends on the design of the haptic device, which presents a complex design space due to its multi-criteria and conflicting character of functional and performance requirements. These requirements include high stiffness, large workspace, high manipulability, small inertia, low friction, high transparency, and cost constraints.

    This thesis proposes a design methodology to improve the realism of force/torque feedback from the VR-based surgical simulator while fulfilling end-user requirements.

    The main contributions of this thesis are:

    1. The development of a model-based and simulation-driven design methodology, where one starts from an abstract, top-level model that is extended via stepwise refinements and design space exploration into a detailed and integrated systems model that can be physically realized.

    2. A methodology for creating an analytical and compact model of the quasi-static stiffness of a haptic device, which considers the stiffness of actuation systems, flexible links and passive joints.

    3. A robust design optimization approach to find the optimal numerical values for a set of design parameters to maximize the kinematic, dynamic and kinetostatic performances of a 6-degrees of freedom (DOF) haptic device, while minimizing its sensitivity to variations in manufacturing tolerances and cost, and also satisfying the allowed variations in the performance indices.

    4. A cost-effective approach for force/torque feedback control using force/torque estimated through a recursive least squares estimation.

    5. A model-based control strategy to increase transparency and fidelity of force/torque feedback from the device by compensating for the natural dynamics of the device, friction in joints, gravity of platform, and elastic deformations.

     

  • 18.
    Ahmad, Aftab
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Andersson, Kjell
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement.
    Sellgren, Ulf
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement.
    An approach to stiffness analysis methodology for haptic devices2011Ingår i: 2011 3rd International Congress on Ultra Modern Telecommunications and Control Systems and Workshops (ICUMT), IEEE conference proceedings, 2011, , s. 8s. 1-8Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this work a new methodology is proposed to model the static stiffness of a haptic device. This methodology can be used for other parallel, serial and hybrid manipulators. The stiffness model considers the stiffness of; actuation system; flexible links and passive joints. For the modeling of the passive joints a Hertzian contact model is introduced for both spherical and universal joints and a simply supported beam model for universal joints. For validation of the stiffness model a modified JP Merlet kinematic structure has been used as a test case. A parametric Ansys FEM model was developed for this test case and used to validate the resulting stiffness model. The findings in this paper can provide an additional index to use for multi-objective structural optimization to find an optimum compromise between a lightweight design and the stiffness performance for high precision motion within a larger workspace.

  • 19.
    Ahmad, Aftab
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Kjell, Andersson
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Sellgren, Ulf
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.).
    A model-based and simulation-driven methodology for design of haptic devices2014Ingår i: Mechatronics (Oxford), ISSN 0957-4158, E-ISSN 1873-4006, Vol. 24, nr 7, s. 805-818Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    High precision and reliable haptic devices are highly complex products. The complexity that has to be carefully treated in the design process is largely due to the multi-criteria and conflicting character of the functional and performance requirements. These requirements include high stiffness, large work-space, high manipulability, small inertia, low friction, high transparency, as well as cost constraints. The requirements are a basis for creating and assessing design concepts. Concept evaluation relies to a large extent on a systematic usage of kinematic, dynamic, stiffness, friction, and control models. The design process can benefit from a model-based and simulation-driven approach, where one starts from an abstract top-level model that is extended via stepwise refinements and design space exploration into a detailed and integrated systems model that can be physically realized. Such an approach is presented, put in context of the V-model, and evaluated through a test case where a haptic device, based on a Stewart platform, is designed and realized. It can be concluded, based on simulation and experimental results that the performance of this deterministically optimized haptic device satisfies the stated user requirements. Experiences from this case indicate that the methodology is capable of supporting effective and efficient development of high performing haptic devices. However, more test cases are needed to further validate the presented methodology.

  • 20.
    Ahmad, Aftab
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Kjell, Andersson
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Sellgren, Ulf
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.).
    An optimization approach towards a robust design of 6-DOF haptic devicesManuskript (preprint) (Övrigt vetenskapligt)
  • 21.
    Ahmad, Aftab
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Kjell, Andersson
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Sellgren, Ulf
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.).
    Model-based control strategy for 6-DOF haptic devicesManuskript (preprint) (Övrigt vetenskapligt)
  • 22.
    Ahmad, Aftab
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Kjell, Andersson
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Sellgren, Ulf
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.).
    Boegli, Max
    Evaluation of friction models for haptic devices2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this work different friction models are evaluated to determine how well these models are suited for performance simulation and control of a 6-DOF haptic device. The studied models include, Dahl model, LuGre model, Generalized Maxwell slip model (GMS), smooth Generalized Maxwell slip model (S-GMS) and Differential Algebraic Multistate (DAM) friction model. These models are evaluated both numerically and experimentally with an existing 6-DOF haptic device that is based on a Stewart platform. In order to evaluate how well these models compensate friction, a model-based feedback friction compensation strategy along with a PID controller were used for position fracking accuracy The accuracies of the friction compensation models are examined separately for both low-velocity and high-velocity motions of the system. To evaluate these models, we use criteria based on fidelity to predict realistic friction phenomena, easiness to implement, computational efficiency and easiness to estimate the model parameters. Experimental results show that friction compensated with GMS, S-GMS and DAA4 models give better accuracy in terms of standard deviation, Root Mean Squared Error, and maximum error between a reference and measured trajectory. Based on the criteria of fidelity, ease of implementation and ease to estimate model parameters, the S-GMS model, which represents a smooth transition between sliding and pre-sliding regime through an analytical set of differential equations, is suggested.

  • 23.
    Alemani, Mattia
    et al.
    KTH.
    Wahlström, Jens
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.). KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement. KTH, Skolan för industriell teknik och management (ITM), Tillämpad maskinteknik (KTH Södertälje). KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Tribologi.
    Olofsson, Ulf
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Tribologi.
    On the influence of car brake system parameters on particulate matter emissions2018Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 396, s. 67-74Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The influence of car brake system parameters on particulate matter emissions was investigated using a pin-on-disc tribometer. Samples from a low-steel friction material and a cast iron disc were tested for different sliding velocities, nominal contact pressures and frictional powers. Disc temperatures were also measured. Their impact on total concentration, size distribution, particle coefficient and transition temperature was analysed. Results show that frictional power is the most significant brake system parameter. However, temperature, as a response parameter, is the most influential, inducing a shift towards the ultrafine particulate fraction and raising emissions. A transition temperature, independent of the system parameters, was identified.

  • 24.
    Amann, Daniel
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Integrerad produktutveckling. Department of Military Studies, Swedish Defence University.
    Kihlander, Ingrid
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.). KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Integrerad produktutveckling.
    Magnusson, Mats
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Integrerad produktutveckling. KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Produktinnovationsteknik.
    Affordability Management And Its Influence On Concept Development2018Konferensbidrag (Refereegranskat)
  • 25.
    Amann, Daniel
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Integrerad produktutveckling.
    Kihlander, Ingrid
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.). KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Integrerad produktutveckling.
    Magnusson, Mats
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Integrerad produktutveckling. KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Produktinnovationsteknik.
    DISRUPTIVE INNOVATION BARRIERS: EXPLORING VALUE NETWORK INERTIA IN COMPLEX LOW-VOLUME PRODUCTS2019Konferensbidrag (Refereegranskat)
  • 26.
    Andersson, Kjell
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Evaluation of a model based learning approach for engineering design2015Ingår i: INTERNATIONAL DESIGN ENGINEERING TECHNICAL CONFERENCES AND COMPUTERS AND INFORMATION IN ENGINEERING CONFERENCE, 2015, VOL 3, 2015, artikel-id UNSP V003T04A013Konferensbidrag (Refereegranskat)
    Abstract [en]

    Project-based education in combination with problem based learning has been very successful, and has contributed to the popularity of engineering design education among students at technical universities. The close connection to industrial problems by the use of industry-connected projects has boosted this popularity still further and to get an insight of future working environments after graduation is very inspiring for the students.

    The curriculum of the Machine Design capstone course at KTH Department of Machine Design covers the whole process from idea generation to manufacturing and testing a final prototype. A major part of the course consists of project work where students develop a product prototype in close cooperation with an industrial partner or with a research project at the department. This means that a major part of the course uses project-based learning as a teaching strategy. In addition, a model-based design methodology is introduced which enables the students to evaluate and "experience" many different behaviors of the product using digital models in a virtual environment. In this way, students can see that many undesirable concepts and flaws can be avoided even before a prototype is manufactured.

    This paper evaluates the use and learning outcome of model-based design in a capstone course in the Engineering Design MSc program at KTH Department of Machine Design. The approach has been used during a period of three years and the effect on the students' learning has been evaluated by a questionnaire after each course. I this paper we compare the results of these questionnaires and discuss implications and general conclusions about this learning approach.

  • 27.
    Andersson, Kjell
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Hagnestål, Anders
    Sellgren, Ulf
    KTH, Skolan för industriell teknik och management (ITM).
    A flexible chain proposal for winch based point absorbers2018Ingår i: Proceedings of the ASME 2018 International Design Engineering Technical Conferences & Computers and Information in Engineering Conference IDETC/CIE 2018: August 26-29, 2018, Quebec City, Quebec, Canada, 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    Ocean wave power is a promising renewable energy source for future energy production. It has however been difficult to find a cost-effective solution to convert the wave energy into electricity. The harsh marine environment and the fact that wave power is delivered with high forces at low speeds makes design of durable mechanical structures and efficient energy conversion challenging. The dimensioning forces strongly depend on the wave power concept, the Wave Energy Converter (WEC) implementation and the actual Power TakeOff (PTO) system. A WEC using a winch as a Power Take-Off system, i.e. a Winch Based Point Absorber (WBPA), could potentially accomplish a low Levelized Cost Of Energy (LCOE) if akey component - a low-cost, durable and efficient winch that can deal with high loads - can be developed. A key problem for achieving a durable winch is to find a force transmitting solution that can deal with these high loads and handle up to 80 million cycles. In this article we propose a design solution for a force transmitting chain in a WBPA system where elastomeric bearings are used as a means to achieve the relative motion between the links in the chain. With this solution no sliding is present and the angular motion is achieved as a deformation in the elastomeric bearing when the chain is winded on a drum. The link was designed primarily to minimize the number of joints in the chain: Thereby the maximum allowed relative angle between the links when rolled up over the drum should be as large as possible within practical limits. The angle is to be handled by the elastomeric bearing. A detailed strength analysis of the link has been performed as well as topology optimization to increase the strength to weight ratio. A test rig for a first proof of concept testing has been developed and the first preliminary test results indicate that this concept with using elastomeric bearings can be a potential solution for a durable chain and should be analyzed further for fatigue conditions and under water operations. 

  • 28.
    Andersson, Kjell
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.).
    Hagnestål, Anders
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elkraftteknik.
    Sellgren, Ulf
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Design of a flexible chain for winch based point absorbers2018Ingår i: Proceedings of NordDesign: Design in the Era of Digitalization, NordDesign 2018, 2018Konferensbidrag (Refereegranskat)
  • 29.
    Andersson, Kjell
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Sellgren, Ulf
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement.
    Reality-driven virtual wheel loader operation2005Ingår i: Proceedings of Virtual Concept 2005, 2005Konferensbidrag (Refereegranskat)
  • 30.
    Andersson, Martin
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.).
    Sosa, Mario
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Olofsson, Ulf
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.).
    The effect of running-in on the efficiency of superfinished gears2016Ingår i: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 93, s. 71-77Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Reduced gear contact losses are necessary to keep operating temperatures, as well as fuel consumption low. In this work, an FZG gear test rig was used to investigate the effect of running-in on superfinished gears with respect to efficiency. This was compared to ground gears where a higher contact pressure yielded higher efficiency. No difference was found between the two running-in procedures when analysing superfinished gears. The effect of running-in on gears decreased when the initial surface roughness was reduced, which initially had an Ra, Rz and Rpk value of 0.08, 0.75 and 0.08 μm respectively. Superfinished gears showed an overall higher efficiency; however, a distinctly lower efficiency was present below 2 m/s when compared to ground gears.

  • 31.
    Asplund, Fredrik
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Mekatronik. KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Grimheden, Martin
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Mekatronik. KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Reinforcing Learning in an Engineering Master’s Degree Program: The Relevance of Research Training2019Ingår i: International journal of engineering education, ISSN 0949-149X, Vol. 35, nr 2, s. 598-616Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Master students at our institute were graduating without acceptable research proficiency. We intervened by shifting our research training from teaching-centred to student-centred, and from research-related subject content to research-related processes. We performed a mixed methods study aimed to confirm there was improved research proficiency without a negative trade-off for our students’ engineering skills. Results indicated improvements to research proficiency, which our students were able to transfer to engineering-related learning activities to increase their ability to achieve engineering synthesis. This outcome was potentially supported by our courses including several perspectives on scientific knowledge production. This implies that research training, rather than having a negative effect on engineering skills, can be helpful in learning diametrically opposing aspects of thinking required by current engineering. As engineering education evolves towards more cross-disciplinary cooperation, this implies the need to pursue the increased opportunities for students to learn about different perspectives on knowledge production.

  • 32.
    Becker, Matthias
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektronik, Elektronik och inbyggda system.
    Lu, Zhonghai
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektronik, Elektronik och inbyggda system.
    Chen, DeJiu
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.). KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Mekatronik.
    Towards QoS-Aware Service-Oriented Communication in E/E Automotive Architectures2018Ingår i: Proceedings of the 44th Annual Conference of the IEEE Industrial Electronics Society (IECON), Institute of Electrical and Electronics Engineers (IEEE), 2018, s. 4096-4101, artikel-id 8591521Konferensbidrag (Refereegranskat)
    Abstract [en]

    With the raise of increasingly advanced driving assistance systems in modern cars, execution platforms that build on the principle of service-oriented architectures are being proposed. Alongside, service oriented communication is used to provide the required adaptive communication infrastructure on top of automotive Ethernet networks. A middleware is proposed that enables QoS aware service-oriented communication between software components, where the prescribed behavior of each software component is defined by Assume/Guarantee (A-G) contracts. To enable the use of COTS components, that are often not sufficiently verified for the use in automotive systems, the middleware monitors the communication behavior of components and verifies it against the components A/G contract. A violation of the allowed communication behavior then triggers adaption processes in the system while the impact on other communication is minimized. The applicability of the approach is demonstrated by a case study that utilizes a prototype implementation of the proposed approach.

  • 33.
    Bejefalk, Thomas
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Integrerad produktutveckling. KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Att konstruera för tillverkning: En arbetsmodell för ett enstyckskonstruerande företag2010Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    SammanfattningDynaMate AB, som är ägare av DynaMate Industrial Services, är ett fristående helägt dotterbolagtill Scania CV AB. Bolaget startade sin verksamhet 1993 och då inledningsvis som enunderhållsavdelning inom och åt Scania. Under första halvåret av 2001 ombolagiserades dockDynaMate AB för att kunna erbjuda produktionsstöd även till andra kunder. Under 2009 bildades såDynaMate Industrial Services AB (DIS), där detta företag idag erbjuder specialkompetens inomautomation, el och mekanik. Med stöd av företagets kompetenser och erfarenhet av produktionsstödlöser de kundens problem från idé till färdig maskin.I Scanias regi har DynaMates uppdrag oftast vilat på enskilda konstruktörer, som då agerat bådeprojektledare, genomförare och slutförare. Som en konsekvens av detta har beslut i många fallendast varit informella och/eller muntliga, där uppdragsdokumentation och eventuellaritningskorrigeringar varit bristfälliga. I samband med att DIS nu, i allt större utsträckning, riktar sigmot andra kunder än Scania, krävs därför större krav på standardiserade arbetssätt med effektivaremetoder för att snabbare kunna angripa och lösa problem.Det primära syftet med detta projekt var att ta fram ett förslag till en standardiserad, enkel ochöverskådlig arbetsmodell för att minska ledtider, produktkomplexitet och underlättakonstruktionsarbetet. Detta för att skapa möjlighet till ökad uppdragsbeläggning på konstruktörerna,samt bättre kvalitetssäkring av produkt gentemot kund.Examensarbetet genomfördes med stöd från litteratur inom aktuellt område, utifrån vilkenintervjufrågor formades. Dessa intervjuer genomfördes med konstruktörer inom DIS avdelning förmekanisk konstruktion samt tillverkande företag.Det sammanställda resultatet visade på flera områden som en konstruktör bör tänka på förenstyckstillverkning. En av de främsta bristerna som påpekades av tillverkning är avsaknad av måtti ritningar. Dessutom förekom åsikter om onödigt fina toleranssättningar, radier och faser. Dessa äralla faktorer som bidrar till ökad ledtid och produktkomplexitet.Det förslag till ny arbetsmodell som presenteras i detta examensarbete är en fasindelad sekventiellmodell, där kund och tillverkning involveras i större utsträckning än idag. Detta för att lättare kunnasäkerställa att tillverkning får korrekt tillverkningsunderlag från konstruktion, samt att produktenuppnår kundens förväntningar. I modellens faser finns dessutom flera riktlinjer som avser vara ettstöd för konstruktören i sitt arbete.

  • 34.
    Bergseth, Ellen
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Influence of surface topography and lubricant design in gear contactsLicentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The purpose of this thesis was to study the influence of manufacturing variations on gear performance. The manufacturing variations inherent in different manufacturing methods were studied to include the effect of real surfaces. Real surfaces have surface irregularities at least on some scale, which can significantly influence how loads are transmitted at the gear contact. To some extent, the lubricant design can help to prevent contact that could lead to tooth failures by forming a protective surface boundary layer. An experimental study was used to consider the compositions of these layers with a surface analysis method.

    In Paper A a robust design approach was used to find out to what extent the current standard for calculation of surface durability treats manufacturing variations and the choice of lubricant. The results show that the simplest calculation method used is not enough to predict the effect of these on surface durability. Additionally, the standard quality levels are poorly incorporated in the standard calculating procedures for surface durability, and the quality of the gear tooth is restricted to include only a few parameters.

    In Paper B a pin-on-disc machine was used to evaluate the tribofilm formation by the additives and the corresponding wear occurring in the boundary lubrication regime in environmentally adapted lubricants. Studies of the additive and base fluid interaction were carried out using glow discharge-optical emission spectroscopy. It was found that the chemically reacted surface boundary layers played an important role in terms of wear. More specifically, the oxide layer thickness had significant influence on wear. The findings also demonstrate the complexity of lubrication design formulations coupled to these layers. For example, it was found that the pre-existing surface boundary layer (before any lubricant had been added) played an important role in allowing the lubricant to react properly with the surfaces.

    The aim of Paper C was to contribute to the knowledge of how different surface topographies, tied to manufacturing methods, influence the early life contact conditions in gears. Topographical measurements of differently manufactured tooth flanks were used as data input to a contact analysis program. The variation in surface topography inherent in the manufacturing method was found to have a strong influence on the contact area ratio.

  • 35.
    Bergseth, Ellen
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement. KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Tribologi.
    Henriksson, Mats
    Scania CV.
    Broukhiyan, Parsa
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Sugutur, Lohith
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Sellgren, Ulf
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Nordin, Erland
    Scania CV.
    EFFECTS OF THRUST WASHER BEARING SURFACE CHARACTERISTICS ON PLANETARY GEAR TRAIN WEAR2017Konferensbidrag (Refereegranskat)
  • 36.
    Bergseth, Ellen
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement. KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Tribologi.
    Söderberg, Anders
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement. KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Tribologi.
    Zhu, Yi
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement. KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Tribologi.
    Olofsson, Ulf
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Study of surface roughness and surface orientation on friction in rolling/sliding contacts: barrel-on-disc versus twin-disc2017Konferensbidrag (Refereegranskat)
    Abstract [en]

    Gears are one of the most important means of mechanical power transmission. Even though the efficiency is high for a gear pair today, further decrease in friction can contribute to lower the fuel consumption. A barrel-on-disc machine (same setup as ball-on-disc) to simulate a rolling/sliding gear contact was used to study the impact of manufacturing method, grinding and superfinishing, on friction. To evaluate the extent to which friction and wear can be diminished by reducing surface roughness and changing surface orientation. Measurement results showed that the change of lubricant had an impact on friction in the mixed to boundary lubrication regimes similar to that of the change of main surface orientation. The results were compared with those from a parallel study involving a twin-disc machine, also used to simulate rolling/sliding contacts (see Figure). Measurements and simulations showed that the barrel-on-disc and twin-disc setups reflected the same friction trends. However, the friction coefficient using the barrel-on-disc setup was almost twice as large as that found using the twin-disc machine. The wear mechanisms also differed: micropits occurred on discs used in the twin-disc set-up whereas normal or no wear was found on the barrel-on-disc specimens. The difference in contact geometry is believed to be the main reason for the higher friction level in the barrel-on-disc machine. A computer contact analysis was used to clarify the differences using perfectly smooth and computer-generated textured surfaces.

  • 37. Bergsjö, D.
    et al.
    Vielhaber, M.
    Malvius, Diana
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Burr, H.
    Malmqvist, J.
    Product lifecycle management for cross-x engineering design2007Ingår i: Proceedings of ICED 2007, the 16th International Conference on Engineering Design, 2007Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper deal with the urgent problem to create integrated PLM solutions in today's European automotive industry. Two European automotive companies have been used as case companies in order to carry out these studies. Configuration management and engineering change management are two information management processes that span throughout the extended company, through engineering domains and through the product lifecycle. This makes them ideal as study objects to create new methods, and to enable PLM for cross-x engineering design. Several guidelines regarding IT system architectures for cross-x PLM are presented, e.g.: modularity, central coordination, standard communication, minimum process redundancy, and general modelling constructs.

  • 38. Bergsjö, Dag
    et al.
    Malvius, Diana
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Use of Information Management Systems from Designers' Perspective2006Ingår i: PROCEEDINGS OF NORDDESIGN 2006 CONFERENCE, REYKJAVIK: UNIV ICELAND, FAC ENGINEERING, , 2006, s. 179-190Konferensbidrag (Refereegranskat)
    Abstract [en]

    In product development research, studies that aim at identifying best practice methods and processes are often conducted. However, it is also essential to learn about causes for bad practice and to gain understanding about how to avoid it. In complex product development, design engineers have to meet the challenges of increased product functionality but their needs for multidisciplinary integration of information are not sufficiently met by existing information management systems. This prevents the design engineers from working at their full capacity and inhibits the possibilities to get support for innovative and value-adding work. This paper aims at identifying reasons for non value-adding work that is linked to inefficient information support, and especially to the use of information management systems. It can be concluded that designers have difficulties to acknowledge positive effects such as better product quality or lower costs that are connected to the use of information management systems. It is argued that one potential means for improved information integration is by managing a trade-off between standardised and customised IT tools and systems.

  • 39.
    Bernemyr, Hanna
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Volatility and number measurement of diesel engine exhaust particles2007Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Today, emission legislations for engine exhaust particles are mass based. The engines of today are low-emitting with respect to particle mass, with the emissions approaching the detection limit of the current measurement method. This calls for new and improved measurement methods. Both from the point of view of the engine developers and regarding human health effects, particle number seem to be the particle property of greatest interest to legislate upon. Recently, a proposal for a new particle number based measurement methodology has been put forward by the United Nations Economic Commission for Europe (UN ECE).

    The gas and particle mixture (the aerosol) of engine exhaust is not a stable system. The size and the number of the particles change over time as the temperature and pressure change. Particle number measurements call for dilution which changes the gas-phase concentrations of the condensing gases. The dilution process alters the conditions in the aerosol and thereby influences the measurements. Within the current project it was desired to better understand the outcome of particle number measurements and the complexities of particle sampling, dilution and conditioning prior to measurements.

    Two experimental set-ups have been developed within the project. The first system includes a rotating disc diluter followed by a volatility Tandem Differential Mobility Analyser (v-TDMA). The second set-up, called the EMIR-system, includes ejector diluters in series followed by a stand-alone Condensation Particle Counter (CPC). After the development of these experimental set-ups, the v-TDMA has been used to study the volatility and the size distributed number concentration of exhaust particles. The EMIR-system was used for total number concentration measurements including only the solid fraction of the aerosol.

    The experimental work has given practical experience that can be used to estimate the benefits and disadvantages of upcoming measuring methodology. For the engine developers, in order to produce engines that meet future legislation limits, it is essential to know how the measurement procedure influences the aerosol. In summary, the experimental studies have shown that the number of nucleation mode particles is strongly affected by varied dilution. No upper threshold value of the dilution has been found where the dilution effect diminishes. The volatility studies have shown that it is mainly the nucleation mode particles that are affected by heat. The v-TDMA instrument have shown to be a sensitive analytical tool which, if desired to use for further engine exhaust particle characterization, needs some development work. Experimental work with the EMIR-system, which in principle is similar to the instruments proposed for a future standard, shows that these types of measurement systems are sensitive to small changes in the detector cut-off. The major outcome of the project lies in the new detailed knowledge about particle number measurements from engines.

  • 40.
    Bernemyr, Hanna
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Ström, Johan
    Westlund, Anders
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.).
    Experimental Evaluation of a Rotating Disc DiluterIngår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851Artikel i tidskrift (Refereegranskat)
  • 41.
    Billgren, Johan
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Marqvard, Frederik
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.).
    Intelligent klämtång: Produktutveckling av ett nytt klämverktygför pacemakerelektrodtillverkning2011Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    SammanfattningDetta examensarbete är ett produktutvecklingsprojekt som har utförts på beställning av St. Jude Medical. Syftet med projektet har varit att undersöka och förbättra den klämprocess som skapar ett klämförband på pacemakerelektroder. Processen sammanfogar tre komponenter genom klämning och detta sker idag med en pneumatisk klämtång. Denna process är mycket operatörsberoende och ett antal förbättringsområden finns.Projektet har fokuserat på att nå upp till de listade kraven som, i samarbete med St Jude Medical, tagits fram för att förbättra den befintliga processen. En grundlig förstudie genomfördes där företagets befintliga klämprocess med tillhörande klämtång och olika klämtekniker på marknaden undersöktes. Arbetet har skett i nära samarbete med elektrodutvecklingsavdelningen på St Jude Medical. Deras behov och önskemål har integrerats i arbetet genom en kravorienterad produktutveckling.Projektets mål var att ta fram en intelligent klämtång som skulle inkludera funktioner som möjliggör kvalitetssäkring av det utförda klämförbandet.Projektet resulterade i en klämtångsprototyp med avseende att minimera operatörsberoendet i klämprocessen samt eventuellt en möjlighet att reducera behovet av stickprovskontroller. Prototypen drivs av en reglerbar elektrisk servomotor med positionsfeedback. Prototypen kontrollerar klämdjup, klämkraft, elektrodposition samt att alla komponenter i förbandet är på plats. Efter genomförd klämning ges kvittens till operatören huruvida klämning var godkänd eller ej. Ett PC-interface gör processövervakning och manuella verktygsinställningar möjligt. Tången sparar klämdata för varje utförd klämning och möjliggör således processpårbarhet.Slutsatsen av arbetet är att St Jude Medical bör vidareutveckla konceptet med en intelligent klämtång. Prototypen visar att det finns stora möjligheter att förbättra dagens klämprocess genom att ersätta den befintliga klämtången.

  • 42.
    Bratt, Maja
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Samuelsson, Hanna
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Framtidens pumpstation: Underlag för vidareutveckling av pumpstationer för trycksatta avlopp2010Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    ITT Water & Wastewater (ITT) är en ledande leverantör och tillverkare av dränkbara pumpar, luftare och omrörare. Examensarbetet fokuserar på pumpstationer för trycksatta avloppssystem. ITT vill genom detta få ett underlag för vidareutveckling av pumpstationerna Compit och Micro 7G, i syfte att göra dem mer konkurrenskraftiga. Målet med arbetet var att utreda vilka delar av pumpstationerna som är i behov av vidareutveckling och presentera förbättringar.Pumpstationer för trycksatta avlopp består av en pumpsump till vilken en självfallsledning ansluts. Avloppsvattnet pumpas vidare i en trycksatt ledning till det kommunala avloppet. Fördelen med trycksatta avlopp är att de kan dras förbi eventuella hinder samt upp för sluttningar. För att begränsa arbetet genomfördes en fördjupad analys enbart på de exteriöra komponenterna. Dessutom sattes ett krav upp att samtliga komponenter skulle vara oberoende av sumpens storlek.En analys av de befintliga produkterna samt konkurrerande stationer genomfördes för att identifiera använda lösningar. Utifrån detta ställdes en kravspecifikation upp. För utlopp, isolering, förlängning, lock, ventilation och lyft av sumpen utvärderades befintliga lösningar och rekommendationer gavs för lämpligt val av lösning. Med hjälp av olika idégeneringsmetoder togs nya koncept fram för storleksanpassning av inlopp, placering av inlopp på sumpen samt sumpens förankring. De framkomna idéerna vidareutvecklades och utvärderades utifrån hur väl de överensstämde med kravspecifikationen.För en framtida pumpstation rekommenderas en station med hög flexibilitet för att tillfredställa de spretiga kraven på marknaden. Stationen förses med två pluggar för inkoppling av avlopp samt kompletteras med en gummiadapter för att kunna ansluta avloppsrör med olika diametrar. Inloppets placering i höjdled varieras genom att justera sumpens totalhöjd. Som förankring rekommenderas en löstagbar sumpfot i tre delar. För utlopp, isolering, lock, ventilation och lyft lämnas rekommendationer på lösningar.En stor utmaning under arbetet var att ta fram en pumpstation som skulle tillfredställa samtliga marknaders behov. En lösning på detta är att antingen utveckla en anpassningsbar pumpstation eller att dela in marknaderna i mindre segment. Då en stor del av utvecklingsarbetet har baserats på intervjuer med expertis har det ibland varit svårt att utröna vilka krav som speglat verkligheten. För att säkerställa resultatet hade mer objektiva metoder behövts under arbetet.

  • 43.
    Brolin, Nils
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Product Development of Curved Noise & NOx Barrier2010Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Sammanfattning Genom att använda olika produktframtagningsprocesser och metoder tas en ny typ av buller och NOx-skydd fram. Från idé och konceptgenerering till färdig skalmodell. Bullerskyddet är paraboliskt utformat och hänger över vägbanan vilket ger den unika ljudreducerande egenskaper utan att tumma på vägsäkerheten. Genom att utnyttja geometrin, kan en extra ljudreducering om ca 3 [dB] tillämpas. Det motsvarar en halvering av ljudeffekten och kan jämföras med att höja trafikhastigheten från en 70-väg till 90 [km/h] utan att bullernivån höjs. Enligt SS-EN 1794-1/2 får bullerskyddet en klassifikation B3 eller beräknat 24 [dB] ljudreducering. Genom tillbehöret ”Absorbing Arm” ges en möjlighet att även absorbera en del av oljudet på ett effektivt sätt tack vare den paraboliska geometrin. Ytterligare värde får produkten genom sin NOx-reducerande förmåga. Betongytor i NOx-reducerande betong samverkar med självrengörande glas genom titaniumdioxid (TiO2) samt UV-ljus (solen eller UV-lampor i tunnlar) och bryter ned farliga NOx-utsläpp (från trafiken) till ofarliga nitrater. Detta reducerar omgivande utsläpp och förbättrar luftkvaliteten. Bullerskyddet är gjort av flera olika komponenter som ingår i ett stort system av fabriksgjorda moduler som monteras på plats. Detta för att effektivisera planering och konstruktion, samt spara pengar vid nybyggnation av bullerskydd. Modulanpassningen ger också upphov till flexibla system som lätt kan anpassas och ändras efter behov, vilket ger en stor flexibilitet i utformandet.

  • 44.
    Calderon Salmeron, Gabriel Benjamin
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Enabling More Efficient E-Mobility: Grease Development by a Novel Bearing-Grease Test Machine2019Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Införandet av elfordon i bilindustrin utgör en möjlighet för smörjfettproducenter. Olika hastigheter, belastningar och elektriska förhållanden är närvarande i de elektriska fordonens kullager i jämförelse med förhållandena i ett traditionellt förbränningsmotorfordon. Detta kräver utveckling av nya fetter som kan hantera de utmaningar som uppkommer med denna nya teknik. Detta projekt ämnar jämföra två fettförtjockningstekniker genom att installera, utveckla och validera en ny höghastighetslagermaskin (HSBT-maskin) för smörjfettstestning. Denna maskin möjliggör att förhållanden som finns i lagren hos ett elektriskt fordon kan efterliknas. I denna masteruppsats användes spårkullager med beteckningen 6208 för att jämföra smörjfettens mekaniska prestanda. I denna studie jämfördes litiumkomplex- och polypropenfetter genom att analysera friktionsmomentet och den självinducerade temperaturen för de testade kullagersmörjfettskombinationerna. Resultatet av studien visar energibesparingspotentialen för båda smörjfetterna och visar möjligheten att använda HSBT-maskinen för att testa smörjfetter. Detta projekt är det första steget i en ambitiös plan att förbättra e-mobilitet genom smörjfettsforskning. Studien ger indata för framtida utveckling av elektriska maskiner och bidrar till skapandet av nya standarder för testning av fetter för elektriska fordon.

  • 45.
    Cha, Matthew
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Nonlinear Isoviscous Behaviour of Compliant Journal Bearings2012Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Plans to shut down nuclear power plants in some European countries as well as increased electricity production by wind and solar power will increase the work load on hydroelectric power plants in the future. Also, due to the power grid regulations, hydroelectric power plants undergo more frequent start-ups and shut-downs. During such transient periods, a large amplitude shaft motion can occur, especially in the power plants with vertical shafts. Large shaft motion is not desirable because it can lead to a machine failure. Furthermore, performance limitations of conventional white metal or babbitted bearings call for the development of new bearing designs. An outstanding tribological performance can be achieved by introducing compliant polymer liners. At the same time, bearings with compliant liners may alter rotor-bearing system dynamic behaviour compared to the systems with conventional white metal bearings. The research approach of this thesis is to employ nonlinear analysis to provide further understanding of the compliant bearing dynamic response to synchronous shaft excitation.

    Plain cylindrical journal bearings with different compliant liner thicknesses were analysed using a nonlinear approach. The numerical model was verified with an in-house developed code at steady state conditions. Results obtained by the numerical models showed good agreement. After verification of the numerical model for fixed geometry journal bearings, models for tilting pad journal bearings were developed. Results for the tilting pad journal bearing with three pads with line pivot geometry were compared with published data in dynamic conditions. A good agreement was obtained between the two numerical models. The effect of pad pivot geometry on bearing dynamic response was investigated. Vertical and horizontal shaft configurations were compared in terms of the effect of preload factor, pivot offset, tapers and pad inclination angles. Influence of the viscoelastic properties of compliant liners was also studied. All these factors significantly affect bearing dynamic response. It is shown how these factors should be selected to control the journal orbit sizes. It was also shown that the compliant liner provides lower maximum oil film pressure and thicker minimum oil film thickness in the bearing mid-plane in both static and dynamic operating conditions.

  • 46.
    Cha, Matthew
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.). Waukesha Bearings, United Kingdom .
    Glavatskih, Sergei
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.). Ghent University, Belgium .
    Misalignment effects in journal bearings with compliant liner tilting padsManuskript (preprint) (Övrigt vetenskapligt)
  • 47.
    Cha, Matthew
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.). Waukesha Bearings, United Kingdom .
    Glavatskih, Sergei
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.). Ghent University, Belgium .
    Nonlinear dynamic behaviour of vertical and horizontal rotors in compliant liner tilting pad journal bearings: Some design considerations2015Ingår i: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 82, s. 142-152Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Dynamic behaviour of vertical and horizontal rotors in journal bearings with line pivot pads is investigated. Two bearing designs are compared: one with white metal pads and another with compliant liner pads. The influence of elasticity of the liner on the journal orbits is investigated. Some practical aspects of the compliant liner pad design are discussed. Compliant bearing design parameters such as preload factor, pivot offset, radial clearance, viscoelasticity, and pad inclination to control the size of the journal orbit are considered.

  • 48.
    Cha, Matthew
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Glavatskih, Sergei
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Nonlinear Dynamic Response of Compliant Journal Bearings2012Ingår i: CSNDD 2012 – International Conference on Structural Nonlinear Dynamics and Diagnosis, EDP Sciences, 2012, s. 10005-Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper investigates the dynamic response of the compliant tilting pad journal bearings subjected to synchronous excitation. Bearing compliance is affected by the properties of pad liner and pad support geometry. Different unbalance eccentricities are considered. It is shown that bearing dynamic response is non-linear. Journal orbit complexity increases with pad compliance though the orbit amplitudes are marginally affected at low loads. At high loads, the journal is forced to operate outside the bearing clearance. The polymer liner reduces the maximum oil film pressure by a factor of 2 when compared to the white metal liner. The nonlinear dynamic response of compliant tilting pad journal bearings is thoroughly discussed.

  • 49.
    Cha, Matthew
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Isaksson, Patrik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Glavatskih, Sergei
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Influence of pad compliance on nonlinear dynamic characteristics of tilting pad journal bearings2013Ingår i: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 57, s. 46-53Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The effect of pad compliance on the dynamic response of tilting pad journal bearings is investigated. Pad compliance is varied by changing pivot geometry and Young's modulus of pad backing and pad liner. Two pad support configurations are considered: one that allows only circumferential tilt and another one that allows both circumferential and axial tilts. Journal orbits, oil film pressure and oil film thickness are compared and discussed. It is shown that higher pad backing compliance significantly increases the journal orbit size and results in an increase in oil film pressure while oil film thickness is decreased. With a compliant liner, oil film pressure is decreased while oil film thickness is increased. Tapers at the pad edges are essential to increase the global minimum oil film thickness in compliant liner bearings.

  • 50.
    Cha, Matthew
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Kuznetsov, Evgeny
    Glavatskih, Sergei
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    A comparative linear and nonlinear dynamic analysis of compliant cylindrical journal bearings2013Ingår i: Mechanism and machine theory, ISSN 0094-114X, E-ISSN 1873-3999, Vol. 64, s. 80-92Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Dynamic behaviour of compliant cylindrical journal bearings is investigated using linear and nonlinear numerical approaches. Journal motion orbits based on linearized dynamic coefficients are compared to the journal trajectories obtained by the nonlinear transient analysis. Obtained results are presented in terms of orbit amplitude, shape and location. The influence of compliant liner thickness, viscoelastic properties and deformation model is also investigated. A linear model is found to deliver acceptable results at a relatively small shaft unbalance under low to average loads. However, with a journal amplitude motion greater than 37% of the bearing diametral clearance, the linear model should not be used to analyse journal transient motion. Plane strain hypothesis is found to be a proper substitute for a full deformation model when a compliant liner is thinner than 2 mm (for the bearing geometry used in this study). It was also shown that the liner viscoelasticity should be taken into account whenever a compliant liner is relatively thick (in our case, 2 mm). Viscoelasticity of the liner decreases journal amplitude compared to a pure elastic liner.

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