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  • 101. Enflo, Bengt
    et al.
    Hedberg, Claes
    Rudenko, Oleg
    Standing and propagating waves in cubically nonlinear media2006Inngår i: Proceedings of the International Conference Mathematical Modelling / [ed] Nilsson, Börje, American Institute of Physics , 2006, s. 187-195Kapittel i bok, del av antologi (Annet vitenskapelig)
    Abstract [en]

    The paper has three parts. In the first part a cubically nonlinear equation is derived for a transverse finite-amplitude wave in an isotropic solid. The cubic nonlinearity is expressed in terms of elastic constants. In the second part a simplified approach for a resonator filled by a cubically nonlinear medium results in functional equations. The frequency response shows the dependence of the amplitude of the resonance on the difference between one of the resonator's eigenfrequencies and the driving frequency. The frequency response curves are plotted for different values of the dissipation and differ very much for quadratic and cubic nonlinearities. In the third part a propagating N-wave is studied, which fulfils a modified Burgers' equation with a cubic nonlinearity. Approximate solutions to this equation are found for new parts of the wave profile.

  • 102. Englund, Thomas
    Dynamic characteristics of automobile exhaust system components2003Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Demands on emission control, and low vibration and noise levels have made the design of automobile exhaust systems a much more complex task over the last few decades. This, combined with increasing competition in the automobile industry, has rendered physical prototype testing impractical as the main support for design decisions. The aim of this thesis is to provide a deeper understanding of the dynamic characteristics of automobile exhaust system components to form a basis for improved design and the development of computationally inexpensive theoretical component models. Modelling, simulation and experimental investigation of a typical exhaust system are performed to gain such an understanding and evaluate ideas of component modelling. Modern cars often have a gas-tight bellows-type flexible joint between the manifold and the catalytic converter. This joint is given special attention since it is the most complex component from a dynamics point of view and because it is important for reducing transmission of engine movements to the exhaust system. The joint is non-linear if the bellows consists of multiple plies or if it includes an inside liner. The first non-linearity is shown to be weak and may therefore be neglected. The non-linearity due to friction in the liner is, however, highly significant and gives the joint complex dynamic characteristics. This is important to know of and consider in exhaust system design and proves the necessity of including a model of the liner in the theoretical joint model when this type of liner is present in the real joint to be simulated. It is known from practice and introductory investigations that also the whole system sometimes shows complex dynamic behaviour. This can be understood from the non-linear characteristics of the flexible joint shown in this work. An approach to the modelling of the combined bellows and liner joint is suggested and experimentally verified. It is shown that the exhaust system is essentially linear downstream of this joint. Highly simplified finite element models of the components within this part are suggested. These models incorporate adjustable flexibility in their connection to the exhaust pipes and a procedure is developed for automatic updating of these parameters to obtain better correlation with experimental results. The agreement between the simulation results of the updated models 5 and the experimental results is very good, which verifies the usability of these component models. A major conclusion is that in coming studies of how engine vibrations affect the exhaust system it may be considered as a linear system if the flexible joint consists of a bellows. If the joint also includes a liner, the system may be considered as a linear sub-system that is excited via a non-linear joint.

  • 103. Englund, Thomas
    et al.
    Wall, Johan
    Ahlin, Kjell
    Broman, Göran
    Automated updating of simplified component models for exhaust system dynamics simulations2002Konferansepaper (Fagfellevurdert)
    Abstract [en]

    To facilitate overall lay-out optimisation simplified component models for dynamics simulations of automobile exhaust systems are desired. Such optimisation could otherwise be computationally expensive, especially when non-linear analyses are necessary. Suggestions of simplified models of the mufflers and the catalyst are given. To account for the flexibility at the connections between those components and the pipes short beam elements with individual properties are introduced at these locations. An automated updating procedure is developed to determine the properties of these beam elements. Results from an experimental modal analysis are used as the reference. The theoretical model of the exhaust system is built in the finite element software ABAQUS. The updating procedure uses the sequential quadratic programming algorithm included in the Optimization Toolbox of the software MATLAB to minimise the sum of the differences between experimentally and theoretically obtained natural frequencies. Constraints are used on the correlation between the experimentally and theoretically obtained mode shapes by considering the MAC-matrix. Communication between the two software packages is established by an in-house MATLAB script. The correlation between results from the updated theoretical model and the experimental results is very good, which indicates that the updating procedure works well.

  • 104. Englund, Thomas
    et al.
    Wall, Johan
    Ahlin, Kjell
    Broman, Göran
    Dynamic characteristics of a combined bellows and liner flexible joint2004Inngår i: Journal of Automobile Engineering, ISSN 0954-4070 , Vol. 218, nr 5, s. 485-493Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A bellows combined with an inside liner and an outside braid is commonly used as a flexible joint in automobile exhaust systems to reduce transmission of engine movements to the exhaust system. It greatly influences the dynamics of the complete system. Understanding of its dynamic characteristics and a modelling method that facilitates systems simulation are therefore desired. This has been obtained in earlier works for the bellows itself. In this work an approach to the modelling of the combined bellows and liner joint is suggested and experimentally verified. Simulations and measurements show that the liner adds significant non-linearity and makes the characteristics of the joint complex. Results are presented for the axial and the bending load cases. In torsion, influence of the liner is negligible. Peak responses are significantly reduced when the excitation level approximately corresponds to the friction limit of the liner. The complexity of the combined bellows and liner joint is important to know of and consider in exhaust system design and proves the necessity of including a model of the liner in the theoretical joint model when this type of liner is present in the real joint to be simulated.

  • 105. Englund, Thomas
    et al.
    Wall, Johan
    Ahlin, Kjell
    Broman, Göran
    Significance of non-linearity and component-internal vibrations in an exhaust system2002Konferansepaper (Fagfellevurdert)
    Abstract [en]

    To facilitate overall lay-out optimisation inexpensive dynamics simulation of automobile exhaust systems is desired. Identification of possible non-linearity as well as finding simplified component models is then important. A flexible joint is used between the manifold and the catalyst to allow for the motion of the engine and to reduce the transmission of vibrations to the rest of the exhaust system. This joint is significantly non-linear due to internal friction, which makes some kind of non-linear analysis necessary for the complete exhaust system. To investigate the significance of non-linearity and internal vibrations of other components a theoretical and experimental modal analysis of the part of a typical exhaust system that is downstream the flexible joint is performed. It is shown that non-linearity in this part is negligible. It is also shown that shell vibrations of the catalyst and mufflers as well as ovalling of the pipes are negligible in the frequency interval of interest. The results implies, for further dynamics studies, that the complete system could be idealised into a linear sub-system that is excited via the non-linear flexible joint, that the pipes could be modelled with beam elements and that the other components within the linear sub-system could also be modelled in a simplified way. Such simplified component models are suggested. The agreement between theoretical and experimental results is very good, which indicates the validity of the simplified modelling.

  • 106.
    Ericksson, Olers Marie
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Rae, Geneva
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Smolyaninova, Julia
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Meeting the Challenge of Social Sustainability: governance for profound change2006Independent thesis Advanced level (degree of Master (One Year))Oppgave
    Abstract [en]

    While many organisations, including business and civil society, have recognized the imperative of sustainable development, without structural changes to an organisations’ governance system, sustained change is impeded. The Natural Step (TNS) Social Template is hereby expanded to guide organisations to develop systems for decision-making, information generation and distribution, and resource allocation that allows for, rather than inhibits, change capacity. A systemic approach to organisational development that does not undermine the capacity of their members to meet their needs can contribute to increased productivity, member engagement and commitment, and drive the innovation necessary for altering our complex, dynamic social-ecological systems in alignment with sustainability. Our research explores the internal factors that may create barriers to organisational change and sustainability. In addition, we synthesise basic human needs, systems’ science, and organisational change research into concrete guidelines for strategic sustainable development within the TNS Social Template framework. We aim to provide an integrated approach for internal social sustainability and strategic planning for improved governance systems.

  • 107. Ericson, Åsa
    et al.
    Johansson, Christian
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Nergård, Henrik
    Manufacturing knowledge: Going from production of things to designing value in use2015Inngår i: International Journal of Intelligent Decision Technologies, ISSN 1872-4981, E-ISSN 1875-8843, Vol. 9, nr 1, s. 79-89Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A new vision in manufacturing is to develop product-service integrated value solutions. Today, few firms have fully realized this vision because they are not able to support the reasoning in the early stages of design. The purpose of this paper is to discuss engineers' cognitive challenge when replacing the core product rationale with value logic. The paper problematizes engineering design by dividing knowledge into the categories technically constructed (explicit) and socially constructed (tacit). In doing so, this study contributes the assumed effects of a perspective shift that could guide the development of computational tools.

  • 108.
    Feng, Gao
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    A., Adelere Oluwafemi.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    COMPUTATIONAL ANALYSIS OF GAS SOLID FLOW IN A PNEUMATIC DRYER2008Independent thesis Advanced level (degree of Master (One Year))Oppgave
    Abstract [en]

    This work presents a design of drying small food particles like tea, tobacco with a reduced height of about fifty percent compared to the convectional straight type. The geometry is designed such that, the particle leave the dryer at an average constant time, to prevent variation in the dryness properties, Simulation result of straight type dryer in FLUENT, the commercial software is validated by industrial data implemented in MATLAB, which shows reasonable agreement. A reduced height type with a swirling or screw type is designed to reduce the height and also maintain the drying residence time.

  • 109.
    Fitzgerald, Shannon E.
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    A., Estela Luck
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Morgan, Anne L.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Strategies for Sustainable Supply Chain Management: Supplier Interaction Devices2007Independent thesis Advanced level (degree of Master (One Year))Oppgave
    Abstract [en]

    In a competitive business environment that requires strategy and innovation to improve the bottom line, supply chain management has been vital in creating competitive advantage. Increasingly, companies are also identifying sustainability as an opportunity to create competitive advantage. This project explores supply chains as a leverage point in advancing sustainable development. Corporations have developed different tools to interact with their suppliers on sustainability. Three of these devices were analyzed against a framework for strategic sustainable development to identify some of their strengths and weaknesses. A general set of criteria for sustainable supply chain management devices that employs a strategic, whole-systems perspective was then developed.

  • 110.
    Fogelqvist, Chandanie
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Thomsson, Johan
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Hansen, Robert
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Mätning av abrasivflöde för vattenskärningsmaskiner2004Independent thesis Basic level (degree of Bachelor)Oppgave
    Abstract [sv]

    The content of the following report is the summarized result of three students thesis at Blekinge Institute of Technology in co-operation with Water Jet Sweden AB. This report will give the reader a description of principles how to measure the abrasive mass flow in a waterjet cutting system. The work began with a visit to Water Jet Sweden AB to get a closer look at the problem. When the analysis of the problem was done the criteria were defined in the form of demands and desires. The main task of the criteria was to guide the search for the solution. The work proceeded with an extensive search for abrasive flow meters along with obtaining information about flow measurement in general. When the search for abrasive flow meters resulted in nothing all the efforts were concentrated on finding a principle of measurement that could cope with the criteria. A number of commonly accepted principles for measurement of mass flow was studied and evaluated. Those passing the evaluation were subject to another more extensive review. In this review the only conclusion was that none of the principles could be dismissed without practical testing. Water Jet Sweden AB were asked which principle/principles of measurement they were most interested in. After coming to an agreement two closely related principles of measurement were chosen to undergo practical studies. A number of different abrasive flows were simulated and in some cases a distinct variation of the signal value could be observed. Everyone involved in this project knew from the beginning that it was extensive. Even though no prototype was presented, this work represents a good foundation for future development.

  • 111.
    Frankowski, Hyuma
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    McKeown, Kate
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Mulligan, Joel
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Building an International Cycling Community2009Independent thesis Advanced level (degree of Master (One Year))Oppgave
    Abstract [en]

    With the increasing population and development of cities, addressing urban transportation is predicted to become a greater challenge. Cycling presents the opportunity to address urban mobility demands without the same degree of environmental, economic and social costs associated with conventional motorized transportation. The intent of this paper is to identify the commonalities and differences between cycling organisations, and what some examples of actions that take advantage of opportunities between these organisations could be. Backcasting from scientifically derived sustainability principles within the Framework for Strategic Sustainable Development was used to validate our research topic. Qualitative research proceeded in four phases. Methods included: literature reviews, field visit, interviews, five-level and SWOT analyses, brainstorming and prioritisation. Research found communication and knowledge transfer within and between cycling organisations could be improved, but doing so requires leadership and resources that are usually lacking. Research also found that there is a desire to present cycling in an inspiring way, but there is a lack of expertise in doing so despite the current unprecedented increase in interest, initiatives and resource allocation related to cycling. As cycling gains more support, it will likely encourage a progressive shift throughout the entire transportation sector toward more sustainable development. This ultimately can play a significant role in moving toward a sustainable society.

  • 112.
    França, Cesar L.
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Maddigan, Kate
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    White, Kyle
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Sustainability Opportunities and Challenges of the Biofuels Industry2005Independent thesis Advanced level (degree of Master (One Year))Oppgave
    Abstract [en]

    Liquid biofuels are being produced to displace fossil fuels for transportation, with bioethanol and biodiesel being the primary biofuels produced for this purpose in the world today. While there is consensus on the need for a sustainable biofuels industry, there is little consensus on how to proceed to avoid environmental and social degradation with global biofuel production. A literature review of Life Cycle Analysis (LCA) data, and the generic Strategic Life-Cycle Management (SLCM) and Template for Sustainable Product Development (TSPD) approaches, helped to inform the creation of a specific tool for sustainable industrial biofuels development, called the TSPD for biofuels. Other data collection involved expert and industry dialogue, as well as stakeholder feedback, on the content of the TSPD. Results showed a variety of sustainability challenges and opportunities, the most significant of which concerns agricultural production. Compelling measures for a sustainable biofuels industry include: cooperation among all stakeholders using a systems approach based on strategic sustainable development, sustainable biofuels certification; and government policies to stimulate research into new technologies and feedstocks, as well as to reduce consumption and increase efficiency.

  • 113.
    Fredericks, Liane
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Garstea, Roman
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Monforte, Sergio
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Sustainable Tourism Destinations: A Pathway for Tour Operators2008Independent thesis Advanced level (degree of Master (One Year))Oppgave
    Abstract [en]

    This paper examines the relationship between tour operators and their existing tourism destinations. The intent is to help the tour operators plan strategically for building the sustainability of their destinations. A Framework for Strategic Sustainability Development, based on scientific consensus, was used to structure this work. Interviews with tour operators and tourism experts gave practical insight complementing the literature review and case studies analysed during the research. The key findings were the need for tour operators to: consider a whole-systems perspective; cooperate with the tourism destination to build a common vision of success and a clear understanding of sustainability; and to prioritise their actions based on achieving the vision. From this the authors proposed guidance notes to assist tour operators in addressing these barriers. The paper concludes that tour operators can play a major role in building a sustainable society while perpetuating the tourism industry. In order to do so their actions must be chosen and managed correctly. This involves cooperation with the destinations throughout the strategic planning process and for all involved to be on the same page in terms of the end goal, a sustainable society.

  • 114. Fredin, Johan
    Modelling, Simulation and Optimisation of a Machine Tool2009Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    To be competitive in today’s global market it is of great importance that product development is done in an effective and efficient way. To enhance functionality, modern products are often so-called mechatronic systems. This puts even higher demands on the product development work due to the complexity of such products. Simulation and optimisation have been proven to be efficient tools to support the product development process. The aim of this thesis is to study how the properties of mechatronic products can be efficiently and systemically predicted, described, assessed and improved in product development. An industrial case study of a water jet cutting machine investigates how simulation models and optimisation strategies can be efficiently developed and used to enhance functionality, flexibility and performance of mechatronic products. The knowledge gained from the case study is shown to be useful for companies developing machine tools. Most likely it is also useful for developers of other mechatronic products. The thesis shows that with the presented optimisation strategies, comprising a mix of different computerised optimisation algorithms and more classical engineering work, design problems with a large amount of design variables can be solved efficiently. A specific result is a validated simulation model for simulation and optimisation of a water jet cutting machine. As all mechatronic disciplines of the machine tool are considered simultaneously, synergetic effects can be utilised. Optimisation studies show a significant potential for improving manufacturing accuracy, for manufacturing speed and for a more light-weight design. Carrying out simulation and optimisation has also provided a great amount of information about the studied system, potentially useful in coming product development work. By reducing the number of physical prototypes through simulation and optimisation, the resource consumption during product development is reduced. Also, with more optimised products the resource consumption can be significantly reduced throughout the whole use phase. These benefits support the competitiveness of the product developing company as well as a sustainable development of society as a whole.

  • 115.
    Fredin, Johan
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Speaker that uses the non-linearity in air to create sound2005Independent thesis Advanced level (degree of Master (One Year))Oppgave
    Abstract [en]

    The aim of this work was to investigate theoretically and experimentally the fact that it is possible to create sound by using the nonlinearity in air. A speaker was built verifying the theory that if at least two high frequencies at high amplitude is propagating through a nonlinear medium, for example air, the difference frequency of these two is created in mid air. Measurements and simulations were performed on what the pressure distribution from a ultrasonic transducer looks like.

  • 116.
    Fredin, Johan
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Jönsson, Anders
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Broman, Göran
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Holistic methodology using computer simulation for optimisation of machine tools2012Inngår i: Computers & industrial engineering, ISSN 0360-8352, E-ISSN 1879-0550, Vol. 63, nr 1, s. 294-301Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Virtual machine concepts supporting optimisation of machine tools have been developed in earlier work. The virtual machine concept is a tool that can describe the behaviour of a machine tool while considering the interaction between mechanics of the machines and the control system. Considerable amount of work has been done proving the concept and showing the potential of such a design tool in different contexts. Several studies have shown the potential of using the virtual machine concept, although, no work has been found that is exploring the potential of a full optimisation study. The aim of this work is to show the potential of the virtual machine concept in an optimisation study of the complete machine tool, including the mechanical system, parameters in the control system, the NC-code as well as choice of servo and drive systems. An efficient optimisation strategy is presented, making it possible to solve the complex optimisation problem within a reasonable amount of time. A combination of optimisation algorithms is used to achieve a fast and accurate way of solving the complex task to optimise the complete machine tool. Genetic algorithms, gradient based algorithms and more traditional hands on engineering are used for solving the optimisation problem. Post processing and data mining is suggested as a way of extracting as much information as possible from optimisation results with the aim to increase the knowledge about the studied system. An important conclusion is that the virtual machine should support the decision making in product development, not replace the product developers as regards decision making.

  • 117.
    Fulson, Karl A.
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Seabrooke, Amy
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Strategic Community Economic Development and Small Business: Cooperation for Sustainability2005Independent thesis Advanced level (degree of Master (One Year))Oppgave
    Abstract [en]

    This thesis aims to increase the knowledge and capacity of Canadian communities and their small businesses in order to enable their transition towards sustainability. This was accomplished through interviews with Canadian Community Economic Development (CED) experts, and surveys from Small Business (SB) operators in Canmore, Alberta, Canada. We suggest the potential roles for CED proponents and SB operators include: (1) Shared development of community vision; (2) Local business networks for sustainability; (3) Community capacity building through dialogue.

  • 118.
    Ghazisaeidi, Hamid
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    A Description of the Anisotropic Material Behaviour of Short Glass Fibre Reinforced Thermoplastics Using FEA.2006Independent thesis Advanced level (degree of Master (One Year))Oppgave
    Abstract [en]

    Abstract: The aim of this work is to investigate and present a theoretical method to describe the anisotropic material properties of short glass fibre reinforced thermoplastics. In this work, the injection moulding process simulation in SIGMASOFT is combined with ABAQUS by a JAVA interface suggested, aiding a micromechanical model, in order to simulate a steady state response of short glass fibre reinforced thermoplastics under the application of a harmonic force.

  • 119.
    Guarena, Armando Enrique León
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Study on Vibrations induced by Parametric Excitations on Strings2007Independent thesis Advanced level (degree of Master (One Year))Oppgave
    Abstract [en]

    The present thesis work studies the parametrically excited vibrations on bridge stay cables when the natural frequency of the bridge tower is half of the resonance frequency of the cable. This condition is found at the longest stay cables of the Øresund Bridge. Experimental and numerical analysis is carried out based on a simplified scaled model (1:200) of this bridge, replacing the cables by strings made of steel. When parametrically excited vibrations are studied, certain relations between resonance frequencies of bridge tower and cable lead to high vibration levels. The most critical relation is when the tower frequency is double the cable frequency. The case studied here, where the tower frequency is half of the cable frequency, shows to be less severe.

  • 120.
    Gummadi, Sanjay
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Kumar, Akula Jagdeesh
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Optimum Design and Analysis of a Composite Drive Shaft for an Automobile2007Independent thesis Advanced level (degree of Master (One Year))Oppgave
    Abstract [en]

    Substituting composite structures for conventional metallic structures has many advantages because of higher specific stiffness and strength of composite materials. This work deals with the replacement of conventional two-piece steel drive shafts with a single-piece e-glass/ epoxy, high strength carbon/epoxy and high modulus carbon/epoxy composite drive shaft for an automotive application. The design parameters were optimized with the objective of minimizing the weight of composite drive shaft. The design optimization also showed significant potential improvement in the performance of drive shaft.

  • 121.
    Gurindapalli, Praveen
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Lade, Jaya Hari
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Correlation of Sinusoidal Sweep Test to Field Random Vibrations2005Independent thesis Advanced level (degree of Master (One Year))Oppgave
    Abstract [en]

    The vibration load subjected to many products is the combination of several random processes corresponding to different application conditions, such as the various field road load inputs for automotive components. Sometimes the input loads are the combination of random and sinusoidal vibration. Due to the convenience of test setup and monitoring, the sinusoidal vibration sweep tests are often used for product durability validation by many automotive and consumer product manufacturers. It is therefore important to correctly correlate the sweep test to the field vibration. This work presents a tool for transferring the measured field random vibrations into a sinusoidal sweep test by using the damage equivalence technique. This requires that fatigue damage generated in the sinusoidal sweep be equivalent to the damage during the desired lifetime in the field operation. Based on this approach, a correlated lab-test specification, including the vibrations level and test duration, can be determined according to the field random load input, the desired product life goal of a product, and the material structural properties.

  • 122. Gusev, V.A.
    et al.
    Rudenko, Oleg
    The Field of Radiative Forces and the Acoustic Streaming in a Liquid Layer on a Solid Half-Space2010Inngår i: Acoustical Physics, ISSN 1063-7710, E-ISSN 1562-6865, Vol. 56, nr 6, s. 861-870Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The acoustic field and the field of radiative forces that are formed in a liquid layer on a solid substrate are calculated for the case of wave propagation along the interface. The calculations take into account the effects produced by surface tension, viscous stresses at the boundary, and attenuation in the liquid volume on the field characteristics. The dispersion equations and the velocities of wave propagation are determined. The radiative forces acting on a liquid volume element in a standing wave are calculated. The structure of streaming is studied. The effect of streaming on small size particles is considered, and the possibilities of ordered structure formation from them are discussed.

  • 123.
    Gutierrez, Cristhian
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Mallette, Robert
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Odumade, Adebola
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Sustainable Stadia Actualizing the Potential of Community- Owned Stadia Towards Sustainability2008Independent thesis Advanced level (degree of Master (One Year))Oppgave
    Abstract [en]

    Professional sporting events draw staggering crowds to stadia on a yearly basis. This combined, with the prosocial psychological effects of attending professional games and the cultural meaning of stadia to a community, provide excellent opportunities for municipalities to use their stadia in a movement towards global socio-ecological sustainability. While these opportunities are available, the industry is not well established to realize their potential. Our research, through application of the framework for strategic sustainable development (FSSD), offers measures to facilitate such a move. In application of the framework, however, a key threat of professional team monopoly power was identified, putting into question the perpetuation of public ownership over facilities with professional teams as tenants. If a solution is to be reached within this model, a multi-stakeholder approach is endorsed, where reduction of team monopoly power is conceded for the long-term benefits to municipalities.

  • 124. Haller, Kristian
    Acoustical Measurements of Material Nonlinearity and Nonequilibrium Recovery2008Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    A damaged material or a material with non perfect atomic geometry, dislocations or cracks, exhibits two types of characteristic responses to acoustic excitations. First is the fast nonlinear dynamics response that is present as long as the material is excited. As soon as the excitation stops the response disappear. Second is the Slow Dynamics, which detects alterations of the material properties. The properties are affected by, for example, a mechanical pulse, changes in temperature, pressure or humidity. When the cause of alteration stops the material is recovering towards its equilibrium state. This recovering can exist over a long period of time, much longer than the vibration from a mechanical pulse. The techniques used here, both the fast and Slow Dynamics, have been used for NonDestructive Testing to detect damage in objects. All of them are suitable for this purpose, but for different material and geometry different techniques can be advantageous. They offer the possibility to use relatively low frequencies which is advantageous because attenuation and diffraction effects are smaller for low frequencies. Therefore large and multi-layered complete objects can be investigated. Sometimes the position of the damage is required, but it is in general difficult to limit the geometrical extent of low-frequency acoustic waves. A technique is presented that constrains the wave field to a localized trapped mode so that damage can be located. The existence of trapped modes is shown using an open resonator concept and the localization is shown to be successful. The problem with intermittent and changing amplitudes, even when very small, is that the material is really never at equilibrium, or even at steady state. The measurement signal influences the outcome. The material is affected by its strain history and its constantly changing state, the fast and Slow Dynamics are hard to separate. A measurement technique keeping the internal strain constant has been used to minimize the influence of Slow Dynamics allowing observations of only nonlinearity. The influence of temperature is also studied with this technique.

  • 125. Haller, Kristian
    Nonlinear Acoustics Applied to NonDestructive Testing2007Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Sensitive nonlinear acoustic methods are suitable for material characterization. This thesis describes three nonlinear acoustic methods that are proven useful for detection of defects like cracks and delaminations in solids. They offer the possibility to use relatively low frequencies which is advantageous because attenuation and diffraction effects are smaller for low frequencies. Therefore large and multi-layered complete objects can be investigated in about one second. Sometimes the position of the damage is required. But it is in general difficult to limit the geometrical extent of low-frequency acoustic waves. A technique is presented that constrains the wave field to a localized trapped mode so that damage can be located.

  • 126. Haller, Kristian
    et al.
    Hedberg, Claes
    Constant Strain Frequency Sweep Measurements on Granite Rock2008Inngår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 100, nr 6Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Like many materials, granite exhibits both nonlinear acoustic distortion and slow nonequilibrium dynamics. Measurements to date have shown a response from both phenomena simultaneously, thus crosscontaminating the results. In this Letter, constant strain frequency sweep measurements eliminate the slow dynamics and, for the first time, permit evaluation of nonlinearity by itself characterized by lower resonance frequencies and a steeper slope. Measurements such as these are necessary for the fundamental understanding of material dynamics, and for the creation and validation of descriptive models.

  • 127. Haller, Kristian
    et al.
    Hedberg, Claes
    Sound Velocity Dependence on Strain for Damaged Steel2008Konferansepaper (Fagfellevurdert)
    Abstract [en]

    When making acoustic measurements on materials with cracks, there exist two types of behavior that influence the sound velocity monitored through the resonance frequency of the object. One is the material's nonlinearity, and the other is a slow recovery process of the material parameters towards equilibrium called Slow Dynamics. The former is a wave distortion taking place in the presence of the wave while the latter is a slow recovery process that makes the time history of the material state count. For the understanding of the dynamics of these solids it is necessary to be able to separate the effects of nonlinearity and slow dynamics. In this work, this has been accomplished by making measurements on steel at steady-state through keeping the strain constant. Normal frequency sweeps at different strains are compared to constant strain sweeps. As every material state parameter can induce a slow dynamic response it is important to keep control of humidity and temperature. Measurements performed at different temperatures give different results. An example of this is the presented resonance frequency plots for the temperatures 20, 25 and 30 degrees Celcius. © 2008 American Institute of Physics.

  • 128. Haller, Kristian
    et al.
    Hedberg, Claes
    Three Nonlinear NDE Techniques On Three Diverse Objects2005Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Non-Destructive Evaluation has been carried out on three different test objects, with three different methods based on exhibits of slow dynamics and nonlinear effects. The three diverse objects were cast iron, ceramic semi-conductors on circuit boards, and rubber. The three approaches were Higher Harmonics detection (HH), Nonlinear Wave Modulation Spectroscopy (NWMS), and Slow Dynamics (SD). For all of the objects the three approaches were tried. The results showed that for each of the objects, a different method worked the best. The cast iron worked best with nonlinear wave modulation, the ceramic semi-conductors worked well with the higher harmonics detection, while the rubber showed best results with slow dynamics.

  • 129. Haller, Kristian
    et al.
    Hedberg, Claes
    Rudenko, Oleg
    Slow variations of mechanical and electrical properties of dielectrics and nonlinear phenomena at ultrasonic irradiation2010Inngår i: Acoustical Physics, ISSN 1063-7710, E-ISSN 1562-6865, Vol. 56, nr 5, s. 660-664Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The interconnection between variations of elasticity and dielectric permittivity of mesoscopic solid systems under exposure to ultrasound is experimentally observed. A phenomenological theory generalizing Debye’s approach for polar fluids is developed to explain the measured data. The substitution of acoustic measurements by dielectric ones not only simplifies the procedure, but offers new possibilities to remotely evaluate the mechanical properties of materials and natural media.

  • 130. Hallstedt, Sophie
    et al.
    Ny, Henrik
    Robèrt, Karl-Henrik
    Broman, Göran
    An approach to assessing sustainability integration in strategic decision systems for product development2010Inngår i: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 18, nr 8, s. 703-712Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This article aims to explore a new approach to assess company decision systems regarding sustainability-related communication and decision support between senior management and product development levels. The assessment approach was developed in theory and its applicability was directly tested in action research in two small and medium-sized companies and two large companies. The results were validated against experiences made by two management consultancies. Our study indicates that successful companies should: (i) integrate sustainability into business goals and plans, backed up by suitable (ii) internal incentives and disincentives and (iii) decision support tools. Our study also indicates that the new assessment approach can be used as a template to assess the current state of sustainability integration in company decision systems.

  • 131. Hallstedt, Sophie
    et al.
    Thompson, Anthony
    Integrating Sustainability and Innovation Through a Master's Program in Product-Service Systems2010Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The results of unsustainable product innovation are evident worldwide. Products and their usage contribute to global sustainability problems. Companies building competence in innovation for sustainability will therefore gain competitive advantages in the evolving sustainability-driven market at the same time as sustainability is a driving force for innovation. Blekinge Institute of Technology (BTH) has a research group that brings together competences with the unifying purpose of supporting industrial capacity for sustainable product-service system innovation. From this research, it is evident that there is a need for systems innovators who can help create leap frog solutions as well as make sure that incremental improvements fit into a viable strategy towards a sustainable society. Industry needs people who can manage the whole innovation process for sustainability, including need-finding, design, implementation through to remanufacturing. BTH is therefore offering a comprehensive master’s program to prepare people to be systems' innovators for sustainability. This programme is focused where sustainability, innovation and product-service systems (PSS) meet. Supporting areas such as leadership, management and entrepreneurship are also included. The two-year program will allow students to engage in front-edge research results and will be continuously developed in close collaboration with industry to develop a relevant profile for graduates. Students will be engaged in ongoing research projects and have industrial projects. Upon completion, students will have practical experience in using methods and tools that support sustainable product innovation, as well as have a thorough theoretical understanding as a basis for development of new supplementary methods and tools as necessary.

  • 132. Hallstedt, Sophie
    et al.
    Thompson, Anthony
    Sustainability driven product development -some challenges and opportunities for aero industry2011Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Products contribute to global sustainability problems throughout their entire life cycles. The majority of opportunities to influence the sustainability performance of products come when the product is designed – far before it is created or put into use. Within the aeronautics industry, there are specific targets set out by the Advisory Council for Aeronautics Research in Europe (ACARE) with one of the high-level targets being an “ultra green air transport system.” At Volvo Aero, a leading manufacturer of aero engine components, this has turned into concrete design targets like light weight, noise/emission reduction and high reliability. Volvo Aero has been used as a case in this research survey to identify some challenges and opportunities of implementing a sustainability perspective in the product innovation process in the aero industry. The overall purpose of this paper is, then, to discuss these challenges and the associated opportunities to include such a sustainability perspective to reach a sustainability-driven product innovation process.

  • 133.
    Hallstedt, Sophie
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för strategisk hållbar utveckling.
    Thompson, Anthony
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Isaksson, Ola
    Larsson, Tobias
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Ny, Henrik
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för strategisk hållbar utveckling.
    A Decision Support Approach for Modeling Sustainability Consequences in an Aerospace Value Chain2014Inngår i: PROCEEDINGS OF THE ASME INTERNATIONAL DESIGN ENGINEERING TECHNICAL CONFERENCES AND COMPUTERS AND INFORMATION IN ENGINEERING CONFERENCE, 2013, VOL 4, ASME Press, 2014, Vol. 3Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Next generation jet engine technologies are typically driven by performance, value and environmental challenges, and appropriate technologies are developed in international research programs. One on-going engine component technology project at an aerospace component manufacturer aims to develop an engine with less fuel consumption. A likely consequence is higher pressure in the core engine, which leads to higher temperature. One way to handle the higher temperature is using a more advanced Ti-alloy for the product component, which will render a different sustainability profile. One weakness in current decision situations is the inability to clarify and understand the “value” and “sustainability” implications compared to e.g. performance features of concepts. Both “value” and “sustainability” include a rich set of features important for successful introduction of new products and product-service solutions to the market. The purpose with this research is to provide decision support for companies in early development phases for assessment of value and sustainability consequences over product-service system lifecycles. A workshop was held with the aerospace component manufacturer and a value chain partner focusing on material handling, to: i) get a better understanding of activities, flows and ownership related to the studied materials at the two companies, ii) to understand the companies’ perspective at new suggested scenarios with regard to these materials, and iii) define relevant scenarios to look into more in depth from asustainability and value perspective. Three different scenarios were developed with differences in ownership, responsibilities and value streams. It is therefore essential to be able to quickly assess and optimize consequences of such alternative scenarios. Based on the workshop experiences and scenarios, a modeling and simulation approach to assess sustainability and value consequences for the scenarios is proposed. The sustainability consequences are based on a sustainability life cycle assessment and a risk assessment. Key features of the proposed tool include: consideration of the time dimension, societal sustainability consequences, risk assessment, company value assessment, and cost/revenue perspectives.

  • 134.
    Haltrich, Natalie
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Lawton, Ella
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Stack, Geoffrey
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    An Introduction to Needs Based Design2008Independent thesis Advanced level (degree of Master (One Year))Oppgave
    Abstract [en]

    This is a supplement to the thesis entitled "Co-creating community with a Needs Based approach to design and planning", by the same authors. It is meant as an introduction to Needs Based Design, for practical application my developers, designers, planners, architects, municipal governments and all others planning the development of a community.

  • 135.
    Haltrich, Natalie
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Lawton, Ella
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Stack, Geoffrey
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Co-Creating Community with a Needs Based Design Approach to Urban Design and Planning2008Independent thesis Advanced level (degree of Master (One Year))Oppgave
    Abstract [en]

    The development of the human built environment is an essential component to achieving and maintaining a sustainable society. Much has been done to develop tools, techniques and approaches for creating ‘green’ or ‘sustainable’ neighbourhoods yet they rarely demonstrate the capacity to address the wider socio-ecological requirements for achieving success. This paper studies the current approaches to green design and planning, proposes a new approach called Needs Based Design (NBD), and identifies the gaps that exist between the two. Results indicate that NBD is based on a firm foundation, is widely applicable, and can support and spur regional sustainable development initiatives and positive behaviour change within communities. It fills three major gaps identified in current green design by utilising systems thinking and a shared language and framework, and focusing on the needs of individuals within communities. Concerns exist, however, about its reliance on broad community participation and ongoing education. In theory, NBD allows project teams to implement their work within the context of a strategic sustainable development perspective. Recommended now is practical application and testing.

  • 136. Hedberg, Claes
    Basics of Nonlinear Time Reversal Acoustics2009Konferansepaper (Fagfellevurdert)
    Abstract [en]

    An investigation of time reversal of nonlinear and non-dissipative or dissipative plane sound waves was made. Propagation and back propagation is time reversal invariant only when the dissipation is zero and the wave has not been shocked. A wave that has shocked has irretrievably lost part of its content. Still, if the wave and its derivatives are considered continuous there remain in theory forever information about the original signal. Factors like numerical accuracy and noise naturally set limits in practical situations.

  • 137.
    Hedberg, Claes
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Andersson, Sara
    Haller, Kristian
    Hallbratt, Sven-Erik
    Non-contact nonlinear ultrasound scan of a CFRP plate with manufactured damages2013Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A Carbon Fibre Reinforced Plastic plate was manufactured to have internal damages of different types. A nonlinear ultrasound technique was used to scan the plate. Non-contact transmitters of own design were used as transducer, and a contact sensor was used to measure the wave in the composite. Scanning was made perpendicularly with the sensor being on the same side as the transducer. The technique can be adapted in accuracy and speed.

  • 138. Hedberg, Claes
    et al.
    Ghazisaeidi, Hamid
    Variation of High Power Air Transducer2006Konferansepaper (Fagfellevurdert)
    Abstract [en]

    High power ultrasonic transducers are widely used for detecting objects and measuring distances, etc. In actual applications, for the air coupling ones the impedance mismatch between the transducer surface and air is large, so there is only a small amount of energy transmitted. Most of the energy loss occurs during the transformation of energy from the transducer radial cone to the air. The purpose of this study is to investigate different designs of the radial cone of the transducer and analyze their vibration in order to suggest design variations for improved vibration amplitudes. Concerning a piezoelectric ceramic transducer, we focus on two parameters of the transducer radial cone. This report presents schemes for increasing pressure levels.

  • 139. Hedberg, Claes
    et al.
    Ghazisaeidi, Hamid
    Haller, Kristian
    Mfoumou, Etienne
    Design Alterations of a High Power Air Transducer2007Inngår i: Japanese Journal of Applied Physics, ISSN 0021-4922, E-ISSN 1347-4065, Vol. 46, nr 7, s. 4908-4911Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    For certain resonant high-power air transducers exists a radiating cone which is in some way connected to a forcing piezoelectric ceramic. This study focuses purely on the cone structure itself, and the form of excitation that gives desired results on the vibration modes of the cone. In the new design three different parameters are changed from existing devices. They are: 1) the change of the round piezoelectric disc center position to a piezoelectric ring shape, while making the cone center fixed, 2) the cutting of the cone into leaves, and 3) the radial thickness decreasing with radius. In simulations, the new design yields considerably higher vibration amplitudes.

  • 140. Hedberg, Claes
    et al.
    Haller, Kristian
    Double open resonator for localized non-contact acoustic testing2004Konferansepaper (Fagfellevurdert)
    Abstract [en]

    There exist two concepts of open resonators that can be combined into a device for acoustic non-destructive testing. The device is non-contact and based on the fact that an airgap between a transducer surface and the test object can be set into resonance. This occurs for the conditions that makes this an open resonator (open because the air volume is not closed), and the wave field is amplified so that a larger amplitude is reached at the object surface. Let us assume that the object is a plate. When the acoustic wave enters the plate, one can let the frequency be the resonant frequency for one of the modes for the plate thickness. A limited part of the plate may be seen as a resonator, open to the sides. When the conditions for an open resonator is fulfilled for the plate thickness, the wave field will be greatly amplified within a region close to the insonified plate surface, and thus the linear or nonlinear response from this excitation is local. The device may then be used to scan the plate for material parameter changes.

  • 141.
    Hedberg, Claes
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Haller, Kristian
    Method for Monitoring Slow Dynamics Recovery2012Inngår i: Acoustical Physics, ISSN 1063-7710, E-ISSN 1562-6865, Vol. 58, nr 3, s. 713-717Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Slow Dynamics is a specific material property, which for example is connected to the degree of damage. It is therefore of importance to be able to attain proper measurements of it. Usually it has been monitored by acoustic resonance methods which have very high sensitivity as such. However, because the acoustic wave is acting both as conditioner and as probe, the measurement is affecting the result which leads to a mixing of the fast nonlinear response to the excitation and the slow dynamics material recovery. In this article a method is introduced which, for the first time, removes the fast dynamics from the process and allows the behavior of the slow dynamics to be monitored by itself. The new method has the ability to measure at the shortest possible recovery times, and at very small conditioning strains. For the lowest strains the sound speed increases with strain, while at higher strains a linear decreasing dependence is observed. This is the first method and test that has been able to monitor the true material state recovery process.

  • 142. Hedberg, Claes
    et al.
    Haller, Kristian
    Non-contact nonlinear acoustic damage localization in plates. Part 2: Localized resonance through dynamically trapped modes2008Inngår i: Acta Acustica united with Acustica , ISSN 1610-1928 , Vol. 94, nr 1, s. 48-53Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This work is the second part of three that presents new tools to be used for damage localization in plates by nonlinear acoustical methods. It introduces an important in-plane localization technique, which is based on the existence of resonant spatially localized wave fields. The wave from the transducer is acting as a dynamic influence on the plate surface, making the waves reflect in a non-ideal way. The non-ideal reflections make the modes underneath the transducer have different resonant frequencies than the modes beside the insonified area. They appear both for contact and non-contact sources. In the nonlinear damage localization application, the trapped mode wave field interacts with another signal at lower frequency. This results in sidebands around the high frequency whose amplitudes are related to the amount of damage underneath the transducer.

  • 143. Hedberg, Claes
    et al.
    Haller, Kristian
    Arnoldsson, Sven
    Non-contact nonlinear acoustic damage localization in plates. Part 1: Resonance of air between plates2007Inngår i: Acta Acoustica united with Acustica, ISSN 1610-1928, E-ISSN 1861-9959, Vol. 93, nr 1, s. 13-21Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This is the first of three articles that deals with the goal of using non-contact nonlinear acoustic methods for the damage localization in plates. In this first part, the resonant air gap wave field between one active and one passive reflecting plate was investigated experimentally. Of particular interest is the wave field amplitude strength, and its distribution on the passive surface. The wave amplitude may be increased by choosing one plate to be concave, overcoming the nonlinear damping taking place for two flat plates. Applications are connected with an increased wave field having advantages for processes taking place under open conditions and for a non-contact transducers' efficiency of transferring energy into an object. A double resonance gives highest air pressure, while a triple provides most energy in the passive object. By choosing the gap distance, frequency and transducer width, the appearing resonant wave will have a considerably larger amplitude at the object surface. The work through the interface from air to object is investigated and the wave field in a resonant air-plate system is shown.

  • 144. Hedberg, Claes
    et al.
    Haller, Kristian
    Kamakura, Tomoo
    A Self-Silenced Sound Beam2010Inngår i: Acoustical Physics, ISSN 1063-7710, E-ISSN 1562-6865, Vol. 56, nr 5, s. 637-639Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Parametric loudspeakers are transmitting two high power ultrasound frequencies. During propagation through the air, nonlinear interaction creates a narrow sound beam at the difference frequency, similar to a light beam from a torch. In this work is added the physical phenomenon of propagation cancellation, leaving a limited region within which the sound can be heard—a 1 meter long cylinder with diameter 8 cm. It is equivalent to a torch which would only illuminate objects within 1 meter. The concept is demonstrated both in simulation and in experiment.

  • 145.
    Hedberg, Claes
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Johnson, Erland
    Andersson, Sara
    Haller, Kristian
    Kjell, Gunnar
    Hellbratt, Sven-Erik
    Ultrasonic monitoring of a fiber reinforced plastic: steel composite beam during fatigue2012Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The use of composite superstructures on current or newly built steel hulls is a recently emerged technology. The economic estimations predict that the extra costs for putting composite superstructures, with the present safety margins, on steel ships will be paid back in only 2-3 years. This also makes the ships having smaller ecological footprints with less fuel consumption and CO2 emissions. In this stage of development it is needed to ensure the durability of the joints between the steel and glass fiber reinforced plastic. The first step is that the joints must first be proven to withstand fatigue. In this test a 4-meter beam, which represents the joint, were investigated for fatigue progression by a four-point-bending fatigue test. In order to show that ultrasonic material monitoring techniques can be used to monitor the damage progression, the beam was measured during the tests until failure. The test was successful both in showing that the joint could withstand high levels of mechanical exposure, and in that the ultrasonic techniques accompanied the damage progression which means that they may be used on vessels during operation

  • 146.
    Hedberg, Claes
    et al.
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för matematik och naturvetenskap.
    Martinet, Philippe
    Non-linear dynamics in granular materials2007Inngår i: The universality of nonclassical nonlinearity, with applications to / [ed] Paolo, Pier, New York: Springer , 2007, s. 327-336Kapittel i bok, del av antologi (Annet vitenskapelig)
    Abstract [en]

    This book comes as a result of the research work developed in the framework of two large international projects: the European Science Foundation (ESF) supported program NATEMIS (Nonlinear Acoustic Techniques for Micro-Scale Damage Diagnostics) (of which Professor Delsanto was the European coordinator, 2000-2004) and a Los Alamos-based network headed by Dr. P.A. Johnson. The main topic of both programs and of this book is the description of the phenomenology, theory and applications of nonclassical Nonlinearity (NCNL). In fact NCNL techniques have been found in recent years to be extremely powerful (up to more than 1000 times with respect to the corresponding linear techniques) in a wide range of applications, including Elasticity, Material Characterization, Ultrasonics, Geophysics to Maintenance and Restoration of artifacts (paintings, stone buildings, etc.). The book is divided into three parts: Part I - defines and describes the concept of NCNL and its universality and reviews several fields to which it may apply; Part II - describes the phenomenology, theory, modelling and virtual experiments (simulations); Part III -discusses some of the most relevant experimental techniques and applications.

  • 147. Hedberg, Claes
    et al.
    Rudenko, Oleg
    Dissipative and hysteresis loops as images of irreversible processes in nonlinear acoustic fields2011Inngår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 110, nr 5Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Irreversible processes taking place during nonlinear acoustic wave propagation are considered using a representation by loops in a thermodynamic parameter space. For viscous and heat conducting media, the loops are constructed for quasi-harmonic and sawtooth waves and the descriptive equations are formulated. The linear and nonlinear absorptions are compared. For relaxing media, the processes are frequency-dependent. The loops broadens, narrows, and bends. The linear and nonlinear relaxation losses of wave energy are shown. Residual stresses and irreversible strains appear for hysteretic media, and here, a generalization of Rayleigh loops is pictured which takes into account the nonlinearly frequency-dependent hereditary properties. These describe the dynamic behavior, for which new equations are derived.

  • 148.
    Hendry, Daniel
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Silcox, Lawrence
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Yokoyama, Nobuko
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Communicating Sustainability through Design within Retail Environments2007Independent thesis Advanced level (degree of Master (One Year))Oppgave
    Abstract [en]

    This thesis uses a systematic understanding of sustainability informed by human needs, learning and design theory to explore ways in which small retail environments can effectively communicate sustainability concepts. The envisioned outcome of successfully communicating and implementing sustainability within retail environments is a lasting change in people’s daily behaviors. The methods of literature review, surveys, human needs investigation and professional validation are used to develop a behavioral change model centered on human needs and learning as well as six communication guidelines. The appendix of this thesis contains a user-friendly pocket guidebook titled The Six Guidelines for Sustainable Retail. The guidebook is designed as a quick-reference tool for retailers, designers and employees. It contains principles, visuals and concepts of sustainability for daily communication and comprehension purposes.

  • 149.
    Henson, Michael
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Missimer, Merlina
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Muzzy, Stephen
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    The Campus Sustainability Movement: A Strategic Perspective2007Independent thesis Advanced level (degree of Master (One Year))Oppgave
    Abstract [en]

    Society is facing a crisis of un-sustainability. The sector of higher education is well poised to support transition to a sustainable society. This thesis assesses the efforts of the Campus Sustainability Movement (CSM) in the US and Canada relative to a Strategic Sustainable Development Framework. Key findings indicate that the CSM is utilizing tools and engaging in a variety of actions towards sustainability. However, it is largely failing to use systems thinking to understand the complex interrelationships of its actions. Most efforts lack a strategy, and when strategy is present, it follows more from barriers than from a long-term goal. Current efforts mostly focus on environmental sustainability. The authors present a backcasting from principles of sustainability approach as one means to improve the strategy of the CSM. They also propose a vision for higher education that incorporates sustainability principles and fundamental human needs in an attempt to bring some concreteness to both the environmental and social aspects of sustainability in higher education.

  • 150.
    Hu, Min
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Study of Two Models for Tearing Resistance Assessment Using Essential Work of Fracture Method2008Independent thesis Advanced level (degree of Master (One Year))Oppgave
    Abstract [en]

    The thesis takes an insight look into two different models(two-zone and three-zone models)for describe the deformation and fracture behaviour of the tearing ligament.By earlier works,these two different models based on Essential Work of Fracture approach was proved to be capable for predicting the specific total work of fracture along the tear path across all plastic zones. A comparison of these two models was made based on the results from an early experiment. The investigation was based on two-leg trousers tear specimen with constant pre-crack length. The materials used in this work were PET and a laminate composed of PETG/PET. And a finite element simulation will be presented also to show the stress around the crack tip and the deformation of the tear specimen. The commercial software of ABAQUS will be selected to performance the simulation.

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