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  • 1.
    Adamsson, Niklas
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Interdisciplinary integration in complex product development: managerial implications of embedding software in manufactured goods2007Doctoral thesis, comprehensive summary (Other scientific)
    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.

  • 2.
    Adamsson, Niklas
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Management of mechatronics engineering: reflections and propositions2005In: Proceedings of 12th International Product Development ManagementConference, vol. 1, 2005, Vol. 1(3), p. 35-48Conference paper (Refereed)
  • 3.
    Adamsson, Niklas
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Mechatronics engineering: New requirements on cross-functional integration2005Licentiate thesis, comprehensive summary (Other scientific)
    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.

  • 4.
    Adamsson, Niklas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Malvius, Diana
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Formal and informal roles in complex product development2005In: 2005 IEEE International Engineering Management Conference, Vols 1 and 2, 2005, p. 559-563Conference paper (Refereed)
    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.

  • 5.
    Adamsson, Niklas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Zika-Viktorsson, Annika
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Challenges and outlooks for software and electrical engineering in traditional mechanical engineering companies: an investigation into workforce implications2006Article in journal (Other academic)
  • 6.
    Adamsson, Niklas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Zika-Viktorsson, Annika
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Multidisciplinary product development: - a case study of mechatronics enineeringArticle in journal (Other academic)
  • 7.
    Adamsson, Niklas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Zika-Viktorsson, Annika
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    The relative effectiveness of different mechanisms for integrating engineering disciplines in complex product development2007Article in journal (Other academic)
  • 8.
    Adamsson, Niklas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Zika-Viktorsson, Annika
    Understanding the importance of interdisciplinary integration in complex product development2007Report (Other academic)
  • 9.
    Afsharian, Reza
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Theodoropoulos, Antonios
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Modular friction test rig for measuring torque and tension in threaded fasteners2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This report describes the development of a modular friction test rig for threaded fasteners. This device can measure the shank torque and the clamp force during the tightening of threaded bolts, with a size of M3-M14 and clamp length of 30-160mm. The design allows the use of several load and torque cells and the range is up to 100kN clamp load and 200Nm applied torque. The test rig will be used for research purposes by Atlas Copco to determine the frictional characteristics in tightening and will allow the experiments on bolts with several materials, coatings and surface finishes. This report concludes to a design proposal evaluated with analytical methods and a prototype 3D model that demonstrate the working principle of the test rig. The measurements are taken from custom-made sensors that are developed with high standards, are easily interchangeable and can be calibrated individually. In addition, a device is developed to allow the user to change the stiffness of the joint. Finally, a future recommendation is made to allow the measurement of the under-head torque. This proposal is a breakthrough compared to other test rigs, and will assist in verifying the friction measurements and having high precision results.

  • 10.
    Aftab, Ahmad
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Mechatronics.
    Andersson, Kjell
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Sellgren, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Khan, Suleman
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Mechatronics.
    A stiffness modeling methodology for simulation-driven design of haptic devices2014In: Engineering with Computers, ISSN 0177-0667, E-ISSN 1435-5663, Vol. 30, no 1, p. 125-141Article in journal (Refereed)
    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.

  • 11.
    Aftab, Ahmad
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Mechatronics.
    Khan, Suleman
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Mechatronics.
    Andersson, Kjell
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Kinematics and Dynamics of a novel 6-DoF TAU Haptic Device2011In: Proceedings of the 2011 IEEE International Conference on MechatronicsInternational Conference on Mechatronics, April 13-15, 2011, Istanbul, Turkey, IEEE conference proceedings, 2011, p. 719-724Conference paper (Refereed)
    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.

  • 12.
    Agrell, Fredrik
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Control of HCCI by aid of Variable Valve Timings with Specialization in Usage of a Non-Linear Quasi-Static Compensation2006Doctoral thesis, comprehensive summary (Other scientific)
    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.

  • 13.
    Agrell, Fredrik
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Ångström, Hans-Erik
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Eriksson, Bengt
    Wikander, Jan
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Linderyd, Johan
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Control of HCCI During Engine Transients by aid of Variable Valve Timings Through the use of Model Based Non-Linear Compensation2005In: SAE transactions, ISSN 0096-736X, Vol. 114, no 3, p. 296-310Article in journal (Refereed)
    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.

  • 14.
    Agrell, Fredrik
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Ångström, Hans-Erik
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Eriksson, Bengt
    Wikander, Jan
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Linderyd, Johan
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Practical Modeling of HCCI for Combustion Timing Control and Results from Engine Test2005In: KTH Internal Combustion Engine Report MFM, Vol. 162Article, review/survey (Refereed)
  • 15.
    Agrell, Fredrik
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Ångström, Hans-Erik
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Eriksson, Bengt
    Wikander, Jan
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Linderyd, Johan
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    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 Lambda2005Conference paper (Refereed)
    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

  • 16.
    Ahmad, Aftab
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Effective development of haptic devices using a model-based and simulation-driven design approach2014Doctoral thesis, comprehensive summary (Other academic)
    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.

     

  • 17.
    Ahmad, Aftab
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Andersson, Kjell
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Sellgren, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    An approach to stiffness analysis methodology for haptic devices2011In: 2011 3rd International Congress on Ultra Modern Telecommunications and Control Systems and Workshops (ICUMT), IEEE conference proceedings, 2011, , p. 8p. 1-8Conference paper (Refereed)
    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.

  • 18.
    Ahmad, Aftab
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Kjell, Andersson
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Sellgren, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    A model-based and simulation-driven methodology for design of haptic devices2014In: Mechatronics (Oxford), ISSN 0957-4158, E-ISSN 1873-4006, Vol. 24, no 7, p. 805-818Article in journal (Refereed)
    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.

  • 19.
    Ahmad, Aftab
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Kjell, Andersson
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Sellgren, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    An optimization approach towards a robust design of 6-DOF haptic devicesManuscript (preprint) (Other academic)
  • 20.
    Ahmad, Aftab
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Kjell, Andersson
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Sellgren, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Model-based control strategy for 6-DOF haptic devicesManuscript (preprint) (Other academic)
  • 21.
    Ahmad, Aftab
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Kjell, Andersson
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Sellgren, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Boegli, Max
    Evaluation of friction models for haptic devices2013Conference paper (Refereed)
    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.

  • 22.
    Alemani, Mattia
    et al.
    KTH.
    Wahlström, Jens
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.). KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements. KTH, School of Industrial Engineering and Management (ITM), Applied Mechanical Engineering (KTH Södertälje). KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Tribologi.
    Olofsson, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Tribologi.
    On the influence of car brake system parameters on particulate matter emissions2018In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 396, p. 67-74Article in journal (Refereed)
    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.

  • 23.
    Amann, Daniel
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Integrated Product Development. Department of Military Studies, Swedish Defence University.
    Kihlander, Ingrid
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.). KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Integrated Product Development.
    Magnusson, Mats
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Integrated Product Development. KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Product Innovation Technology.
    Affordability Management And Its Influence On Concept Development2018Conference paper (Refereed)
  • 24.
    Andersson, Kjell
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Evaluation of a model based learning approach for engineering design2015In: INTERNATIONAL DESIGN ENGINEERING TECHNICAL CONFERENCES AND COMPUTERS AND INFORMATION IN ENGINEERING CONFERENCE, 2015, VOL 3, 2015, article id UNSP V003T04A013Conference paper (Refereed)
    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.

  • 25.
    Andersson, Kjell
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Sellgren, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Reality-driven virtual wheel loader operation2005In: Proceedings of Virtual Concept 2005, 2005Conference paper (Refereed)
  • 26.
    Andersson, Martin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Sosa, Mario
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Olofsson, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    The effect of running-in on the efficiency of superfinished gears2016In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 93, p. 71-77Article in journal (Refereed)
    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.

  • 27.
    Bejefalk, Thomas
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Integrated Product Development. KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Att konstruera för tillverkning: En arbetsmodell för ett enstyckskonstruerande företag2010Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    DynaMate AB, the owner of DynaMate Industrial Services AB (DIS), is a free-standing whollyownedaffiliate company of Scania CV AB. The company started its business in 1993 initially as asupport and maintenance department within and for Scania solely. During the first six-months of2001 DynaMate’s business was re-formed to also offer its service and production support to otherclients besides Scania. Therefore, in 2009 DynaMate Industrial Services AB was established. Thiscompany offer complete industrial solutions with special skills in the automation, electrical andmechanical areas.In the management of Scania, DynaMates missions has often depended on single designers, playingthe role as both project leader and project member as well as project performer and finisher. As aeffect of this working procedure many crucial decisions have been only verbal and informal, whereimportant task documentation and possible drawings rectifications has been inadequate. The factthat DIS now, continuously increasing in extent, is aiming to other clients than just Scania, a morestandardized working procedure is required. This is important to be able to decrease time from ideato complete solution, and still provide customers with high quality products.The primary task with this project was therefore to develop a working model proposal forimproving designers’ every-day work at DIS, concerning reduced lead time for one-productmanufacturing.This Master Thesis was performed with the support from litterature within associated research area,followed by the formation of a interview questionnaire. All interviews were performed within DISdepartment of mechanical design and with external manufacturing companies.The compiled result indicated several areas that a designer must be aware of when designing formanufacturing. Manufacturers pointed out that the most common defects with constructiondelivered drawings are missing measurements, as well as superflously tolerances, radius’ andchamfers. These factors are all contributing to increased lead time and product complexity.The proposed new working model presented in this Master Thesis is a phase-divided sequentialprocess, where both the customer and manufacturer will be more involved than today. This toensure that the manufacturer will be given complete data from the designer, and that the finalproduct will obtain customer satisfaction.

  • 28.
    Bergseth, Ellen
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Influence of surface topography and lubricant design in gear contactsLicentiate thesis, comprehensive summary (Other academic)
    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.

  • 29. Bergsjö, D.
    et al.
    Vielhaber, M.
    Malvius, Diana
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Burr, H.
    Malmqvist, J.
    Product lifecycle management for cross-x engineering design2007In: Proceedings of ICED 2007, the 16th International Conference on Engineering Design, 2007Conference paper (Refereed)
    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.

  • 30. Bergsjö, Dag
    et al.
    Malvius, Diana
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Use of Information Management Systems from Designers' Perspective2006In: PROCEEDINGS OF NORDDESIGN 2006 CONFERENCE, REYKJAVIK: UNIV ICELAND, FAC ENGINEERING, , 2006, p. 179-190Conference paper (Refereed)
    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.

  • 31.
    Bernemyr, Hanna
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Volatility and number measurement of diesel engine exhaust particles2007Doctoral thesis, comprehensive summary (Other scientific)
    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.

  • 32.
    Bernemyr, Hanna
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Ström, Johan
    Westlund, Anders
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Experimental Evaluation of a Rotating Disc DiluterIn: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851Article in journal (Refereed)
  • 33.
    Billgren, Johan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Marqvard, Frederik
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Intelligent klämtång: Produktutveckling av ett nytt klämverktygför pacemakerelektrodtillverkning2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    AbstractThis Master Thesis is a product development project commissioned by St. Jude Medical. The purpose has been to investigate and improve a crimp process which creates a crimp connection on the pacemaker lead. This process joins three components together, currently using a pneumatic crimp tool. This process is highly operator dependant and there are numerous fields of possible improvements.The focus of this project has been to meet the requirements, regarding improvement of the existing crimp process, which were listed in cooperation with St. Jude Medical. A thorough pre study was conducted where the existing crimp process and tool, along with other crimp techniques on the market were investigated. The work was carried out in close cooperation with the leads development team at St. Jude Medical. Their thoughts and demands have been integrated trough a requirement oriented development process.The goal of this project was to develop an “intelligent” crimp tool that should be equipped with functions which allow quality control of the work performed.The project resulted in a prototype for a new crimp tool, which shall minimize operator dependence in the crimp process and possibly reduce the need of judgment samples. The prototype is power by an electric servo motor with position feedback. The prototype measures crimp depth, crimp force, lead position and controls that all components in the crimp connection is present. By analyzing these parameters, the tool is able to give a quittance to the operator whether or not the crimp was approved. A PC interface makes process monitoring and manual tool settings possible. The crimp tool saves crimp data for every executed crimp connection which enables process traceability.The conclusion of this project is that St. Jude Medical should take the concept of an intelligent crimp tool further. The prototype shows great possibilities to improve the crimp process by replacing the existing crimp tool.

  • 34.
    Bratt, Maja
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Samuelsson, Hanna
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Framtidens pumpstation: Underlag för vidareutveckling av pumpstationer för trycksatta avlopp2010Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    ITT Water & Wastewater (ITT) is one of the leading suppliers and producers of drainable pumps, aerators and mixers. The master’s thesis focuses on stations for pressure sewerage systems. ITT wants to receive a basis for further development of the pump stations Compit and Micro 7G, with the aim to make them more competitive. The thesis’ goal was to investigate which parts of the pump stations are in need of further development and present improvements.Pump stations for pressurized sewerages consist of a tank to which a gravity pipe is connected. The waste water is then pumped through a pressurized pipe to the municipal sewerage. The advantage of pressurized sewerages is that they can be run around potential obstacles and up hill. The work was limited to a deeper analysis of the exterior components. Furthermore a requirement was set that all components should be independent of the tank’s size.An analysis of the existing products and the competitors’ stations was conducted. From this a product requirements specification was made. Regarding outlet, isolation, extension, cover, ventilation and lift of the tank, existing solutions were evaluated and recommendations for suitable choices were given. By using different methods for concept generation new ideas for size adaption of the inlet, placement of the inlet on the tank and the tanks anchoring were generated. The generated ideas were further developed and evaluated according to how they corresponded to the product requirements specification.For a future pump station high flexibility is recommended to satisfy the straggling requirements from the market. The station is equipped with two spigots for connection of the sewerage and is complemented with a rubber adapter for connection of pipes with different diameters. The vertical position of the inlet is varied by adjusting the height of the tank. As anchoring a detachable tank foundation divided into three parts is recommended. Recommendations are given for outlet, isolation, cover, ventilation and lift.A major challenge during the work was to develop a pump station which would satisfy all of the markets needs. A solution to this is to either develop an adaptable pump station or to divide the market into smaller segments. As a major part of the development is based on interviews with skilled persons it has sometimes been hard to establish which of the requirements reflected the reality. To secure the results more objective methods would have been needed during the work.

  • 35.
    Brolin, Nils
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Product Development of Curved Noise & NOx Barrier2010Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Abstract By using different product development processes and methods a new type of noise and NOx barrier is developed, from idea to scale model. The barrier is parabolic shaped and overlays the road, giving it unique attributes that aids the noise reduction ability without intruding on road safety. By using this geometry, an additional 3 [dB] of noise reduction can be estimated. This difference is equal to increasing the speed limit of a 70 [km/h] road to 90 [km/h] without increasing the noise levels. The overall classification according to SS-EN 1794-1/2 of the barrier is B3, giving a noise reduction of an estimated 24 [dB]. With the additional add-on “Absorbing Arm”, the product has the possibility to absorb the noise in an effective way due to its parabolic geometry. Additional value to the product is a NOx-reducing ability, made possible by utilizing NOx-reducing concrete and glass. NOx-particles emitted from the traffic are bound on the surface of the material reacting together with titanium dioxide (TiO2) and UV-light transforming them into harmless nitrates, lowering the surrounding pollution levels. The product is made out of several different components, combined together through a system, which give rise to a pre-manufactured module that are assembled on location. By doing so a more flexible and economical system for planning and constructing efficient noise barriers is presented.

  • 36.
    Cha, Matthew
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Nonlinear Isoviscous Behaviour of Compliant Journal Bearings2012Licentiate thesis, comprehensive summary (Other academic)
    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.

  • 37.
    Cha, Matthew
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.). Waukesha Bearings, United Kingdom .
    Glavatskih, Sergei
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.). Ghent University, Belgium .
    Misalignment effects in journal bearings with compliant liner tilting padsManuscript (preprint) (Other academic)
  • 38.
    Cha, Matthew
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.). Waukesha Bearings, United Kingdom .
    Glavatskih, Sergei
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.). Ghent University, Belgium .
    Nonlinear dynamic behaviour of vertical and horizontal rotors in compliant liner tilting pad journal bearings: Some design considerations2015In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 82, p. 142-152Article in journal (Refereed)
    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.

  • 39.
    Cha, Matthew
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Glavatskih, Sergei
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Nonlinear Dynamic Response of Compliant Journal Bearings2012In: CSNDD 2012 – International Conference on Structural Nonlinear Dynamics and Diagnosis, EDP Sciences, 2012, p. 10005-Conference paper (Refereed)
    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.

  • 40.
    Cha, Matthew
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Isaksson, Patrik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Glavatskih, Sergei
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Influence of pad compliance on nonlinear dynamic characteristics of tilting pad journal bearings2013In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 57, p. 46-53Article in journal (Refereed)
    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.

  • 41.
    Cha, Matthew
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Kuznetsov, Evgeny
    Glavatskih, Sergei
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    A comparative linear and nonlinear dynamic analysis of compliant cylindrical journal bearings2013In: Mechanism and machine theory, ISSN 0094-114X, E-ISSN 1873-3999, Vol. 64, p. 80-92Article in journal (Refereed)
    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.

  • 42.
    Cha, Matthew
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.). Waukesha Bearings, United Kingdom .
    Santos, Ilmar
    Technical University of Denmark, Denmark.
    Glavatskih, Sergei
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.). Ghent University, Belgium .
    Dynamic characteristics of polymers related to compliant bearing desigManuscript (preprint) (Other academic)
  • 43.
    Cha, Yingying
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Tribologi.
    Tu, Minghui
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Tribologi.
    Bergstedt, Edwin
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Tribologi.
    Carlsson, Peter
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Lyu, Yezhe
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Tribologi. KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Olofsson, Ulf
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Silvergren, Sanna
    Elmgren, Max
    Hurkmans, Jennie
    Norman, Michael
    Ombordmätningar av luftburna partiklar i X60 samt på citybanans plattformar2018Report (Other (popular science, discussion, etc.))
  • 44.
    Chitta, Sudeendra
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Elastohydrodynamic lubrication in spur gear and helical gear contacts2012Independent thesis Advanced level (degree of Master (Two Years)), 80 credits / 120 HE creditsStudent thesis
    Abstract [en]

    The gears in a transmission are lubricated to prevent their premature failure as a result of pitting and wear on the tooth surfaces. Furthermore, the lubricant also limits the rise in surface temperature of the gears, which could otherwise lead to failure as a result of scuffing.

    The purpose of this thesis was to construct a fairly realistic theoretical lubrication model for spur and helical gears, the primary output parameters of this model being film thickness and flash temperatures, which would help in the identification of areas on the gear tooth surface prone to the aforementioned modes of failure. This thesis was carried out at the Gear Technology group in Scania CV AB in collaboration with the department of machine design at KTH.

    Gear lubrication is tricky as it entails the determination of parameters such as loads, curvatures, and velocities; which are different along the entire surface of the gear tooth. Primarily the loads are hard to obtain as they are dynamic in nature; the load is shared between different pairs of teeth during motion. The calculation of velocities and curvatures in an area of the gear surface called the tip relief can also not be done in a straightforward manner. These issues were simplified to a large extent with the assistance of a program called Helical 3D; owing to its powerful contact analysis algorithm, values of the film thickness and flash temperatures could be determined in almost every region where contact occurred between the gear teeth.

    The results of the lubrication model showed a reduction in film thickness in the tip relief area of the gear tooth surface; which meant that there were higher chances for the incidence of pitting and wear in this region. This was later confirmed when photographs from experimental tests illustrated a pitting line in the tip relief region of the helical gear. It was also inferred from the model that the occurrence of pitting could be greatly reduced if a quadratic tip relief modification were applied when compared to the existing linear modification used at Scania. Another important conclusion drawn was that thermal effects contributed to a significant decrease in the film thickness. Furthermore, the model showed higher flash temperatures close to the tip of the gear tooth surface, and photographs from experiments conducted showed the prescence of scuffing marks there.

  • 45.
    CLEMEDTSON, JOSEFIN
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    PÄÄJÄRVI, EMELIE
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    To Plant and Grow Innovation: Steering Support for Innovation Processes in Medium Sized Companies2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Being innovative and environmentally sustainable can help companies to achieve success. Depending on the size of the company it can be achieved in different ways. When conducting innovation projects, the level of formal steering support might differ, especially if sustainability wants to be achieved. This thesis aims to answer the question how the need of ensuring the firm’s vision of being environmentally sustainable and use it as a marketing advantage affect the need of formal steering support in innovation projects in medium sized enterprises. Until today research have not addressed this question in a sufficient manner whereas focus has been on “SME’s” (Small and Medium sized Enterprises), small or large companies. Large companies need rather formal processes while smaller companies can be more informal and flexible. This thesis takes the perspective of the medium sized company and investigates their specific needs. A variety of innovation projects have been studied at a medium sized company and insights from it has been combined with literature on innovation processes to find the right balance of formality. The conclusion being drawn is that formality is needed especially in the beginning and in the end of an innovation project for a medium sized company if sustainability wants to be achieved and used as a marketing advantage.

  • 46. Cupillard, Samuel
    et al.
    Cervantes, Michel
    Glavatskih, Sergei
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Thermohydrodynamic analysis of a journal bearing with a microgroove on the shaft2011Conference paper (Refereed)
    Abstract [en]

    In this study, thermohydrodynamic performance of a journal bearing with a microgroove created on the shaft is analysed. A plain journal bearing is modelled using a computational fluid dynamics (CFD) software package. Navier-Stokes and energy equations are solved. The rotor-stator interaction is treated by using a computational grid deformation technique. Results are presented in terms of typical bearing parameters as well as flow patterns. Results are also compared to the bearing with a smooth shaft. The effect induced by a microgroove on pressure distribution is explained for different bearing configurations, eccentricities and microgroove depths. It is shown that the microgroove produces a local drop in pressure which, averaged over one revolution, decreases the load carrying capacity. The load carrying capacity is further decreased by using deeper microgrooves. With thermal effects considered, the microgroove carries more cold lubricant into the warmest regions of the bearing. This effect, more pronounced with deeper microgrooves, is due to a global flow recirculation inside the microgroove, which improve mixing.

  • 47.
    El-Khoury, Jad
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    A Model Management and Integration Platform for Mechatronics Product Development2006Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    Mechatronics development requires the close collaboration of various specialist teams and engineering disciplines. Developers from the different disciplines use domain-specific tools to specify and analyse the system of interest. This leads to different views of the system, each targeting a specific audience, using that audience’s familiar language, and concentrating on that audience’s concerns. Successful system development requires that the views of all developers produced by the different tools are well integrated into a whole, reducing any risks of inconsistencies and conflicts in the design information specified.

    This thesis discusses techniques of managing and integrating the views from various disciplines, taking better advantage of multidisciplinary, model-based, development. A Model Data Management (MDM) platform that generically manages models from the various domain-specific tools used in development is presented. The platform is viewed as a unification of the management functionalities typically provided by the discipline-specific PDM and SCM systems. The unification is achieved by unifying the kind of objects it manages – models. View integration is considered as an integral functionality of this platform.

    In demonstrating the platform’s feasibility, a generic version management functionality of models is implemented. In addition, model integration is investigated for the allocation of system functions onto the implementing hardware architecture. The proposed approach promotes the independent development of the views, allowing developers from each discipline to work concurrently, yet ensuring the completeness, correctness and analysis of any inter-view design decisions made.

    The prototype MDM platform builds on existing technologies from each of the mechanical and software disciplines. The proposed MDM system is built based on a configurable PDM system, given its maturity and ability to manage model contents appropriately. At the same time, the version control functionality borrows ideas from the fine-grained version control algorithms in the software discipline.

    The platform is argued to be feasible given the move towards model-based development in software engineering, bringing the discipline’s needs closer to those of the hardware discipline. This leads the way for an easier and more effective integrated management platform satisfying the needs of both disciplines using a common set of mechanisms.

  • 48.
    Elmqvist-Möller, Christel
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    1-D simulation of turbocharged SI engines: focusing on a new gas exchange system and knock prediction2006Licentiate thesis, comprehensive summary (Other scientific)
    Abstract [en]

    This licentiate thesis concerns one dimensional flow simulation of turbocharged spark ignited engines. The objective has been to contribute to the improvement of turbocharged SI engines’ performance as well as 1 D simulation capabilities.

    Turbocharged engines suffer from poor gas exchange due to the high exhaust pressure created by the turbine. This results in power loss as well as high levels of residual gas, which makes the engine more prone to knock.

    This thesis presents an alternative gas exchange concept, with the aim of removing the high exhaust pressure during the critical periods. This is done by splitting the two exhaust ports into two separate exhaust manifolds.

    The alternative gas exchange study was performed by measurements as well as 1-D simulations. The link between measurements and simulations is very strong, and will be discussed in this thesis.

    As mentioned, turbocharged engines are prone to knock. Hence, finding a method to model knock in 1-D engine simulations would improve the simulation capabilities. In this thesis a 0-D knock model, coupled to the 1-D engine model, is presented

  • 49.
    Engström, Kristina
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Stjernlöf, Lovisa
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Utveckling och konstruktion av motorhus till vindkraftverk2010Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    During the year of 2010 the company GC Windpower worked with the development of two wind power plants, one two-bladed turbine with an effect of 1 MW and one three-bladed turbine with the effect of 2,5 MW. The Master’s of Science thesis concerned the design and development of the nacelle to the windpower plant with an effect of 2,5 MW. The aim of the project was to compile a basis for construction of the nacelle, including drawings, 3D-models, FEM-analysis as well as proposals of suitable materials and manufacturing methods.Requirements of specifications were listed together with the representatives from GC Windpower. The demands affected the design, strength and material choice. To get a solid ground of knowledge in the start of the project a thorough search for information was performed.Many sessions of generating concepts were hold. The focuses of the sessions were both specific areas and the total design of the nacelle. The final result is a combination of solutions of the different areas, and was during the process adjusted after the point of view from the company.To see if the construction would restrain the wind pressure, Finite Elements simulations were made. The simulations were made for different wind forces and with different variations of the nacelle, this to show weaknesses and strengths of the construction.To keep the wall thickness of the nacelle thin, four ribs of glass fiber reinforcement were used. Beams of steel and aluminum were connecting the rear and front with the rest of the housing. Beams of T-profile were used to join the walls with top and bottom, and to connect the nacelle to the frame.The total deformation of the nacelle became 62,2 mm, when the wind speed were 59,9 m/s. The maximum deformation was considered reasonable since the approved limit was 70 mm.

  • 50. Filippov, A.
    et al.
    Shah, F. U.
    Taher, M.
    Glavatskih, Sergei
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.).
    Antzutkin, O. N.
    NMR self-diffusion study of a phosphonium bis(mandelato)borate ionic liquid2013In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 15, no 23, p. 9281-9287Article in journal (Refereed)
    Abstract [en]

    Newly synthesised halogen-free boron based ionic liquids (hf-BILs) composed of chelated orthoborate anions and phosphonium cations have hydrolytic stability, low melting point and outstanding wear and friction reducing properties. We report here the peculiarities of self-diffusion in one representative from this class, trihexyltetradecylphosphonium bis(mandelato)borate, [P6,6,6,14][BMB], in the temperature range of its practical interest, 20-100 °C. NMR techniques demonstrated complicated diffusional behaviour-the ionic liquid can exist in one or two liquid "phases". In the low-temperature range (20-50 °C), two phases coexist where the cations, [P6,6,6,14], are contained mainly in the phase with slower diffusion coefficients while the anions, [BMB], are in the phase with faster diffusion coefficients. Cations have lower diffusion coefficients with a factor of 20 as compared with the anions, an effect which is caused by aggregation of cations into domains due to so-called "hydrophobic interaction" of their hydrocarbon chains. As the temperature rises above 60 °C, the two phases merge into one where both ions have equal diffusion coefficients. This is caused by thermal motion making the cation domains smaller in size and more easily interacting with anions. As a result, anions and cations diffuse in this high-temperature range as a pair.

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