Endre søk
Begrens søket
1234567 151 - 200 of 318
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Treff pr side
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
Merk
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 151. Huang, Yayu
    et al.
    Hu, Xiang Ping
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Shen, Yujie
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Liao, Taohong
    Method of obtaining dynamic stress intensity factor by measuring crack mouth opening displacement on a 3-point bending specimen2012Inngår i: Lecture Notes in Electrical Engineering, Jiaozuo, Henan: Springer , 2012, Vol. 138, s. 1269-1275Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper focuses on how to obtain the Dynamic Stress Intensity Factor by measuring Crack Mouth Opening Displacement on a pre-cracked 3-Point Bending Specimen. During the experiments, one uses impactor to hit on a pre-crack 3-Point Bending Specimen and at the same time uses a high-speed camera to take a set of photos of the crack. Crack Mouth Opening Displacement can then be measured from these photos. According to the relationship of J integral, Crack Open Mouth Displacement and the Dynamic Stress Intensity Factor, the Dynamic Stress Intensity Factor could be obtained. This result could be useful for guiding the practical engineering design.

  • 152. Huang, Yayu
    et al.
    Hu, Xiangping
    Fracture mechanics theoretical modelling and FEM analysis of 3-Point Bending Specimen suffering cyclic loads2011Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Fracture mechanics theoretical modelling and Finite Element Method analysis of a pre-cracked 3-Point Bending Specimen (3PBS) have been conducted in this paper. Using the equivalent system of the specimen, fracture mechanical characteristics have been analyzed and the theoretical Dynamic Stress Intensity Factor (DSIF) is obtained later and used together with the Pairs theorem to analyze the fatigue life time of the specimen. Based on the simulations from ABAQUS, dynamic characteristics of the pre-cracked 3PBS are obtained and verified. The results are further analyzed and discussed with special concern on fracture mechanics characteristics of the material and will provide a guideline for further research and practical design

  • 153. Huang, Yayu
    et al.
    Hu, XiangPing
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Liao, Taohong
    Fracture mechanics analysis of the Dynamic Stress Intensity Factor of 3-Point Bending Specimen suffering cyclic loads2012Inngår i: Applied Mechanics and Materials, Jiaozuo, 2012, Vol. 143-144, s. 503-507Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Fracture mechanics analysis of the Dynamic Stress Intensity Factor of a pre-cracked 3-Point Bending Specimen suffering cyclic loads has been studied. Using the theoretical equivalent system of the pre-cracked 3-Point Bending Specimen, the Dynamic Stress Intensity Factor could be obtained theoretically. The finite element method was then applied to study the dynamic behaviors of the Dynamic Stress Intensity Factor under different cyclic loads' conditions using the standard software ABAQUS. The results have also been analyzed and discussed, which provided a deeper view for the fracture characteristics of the materials and could be used to guide further researches and practical engineering design.

  • 154. Huang, Yayu
    et al.
    Hu, Xiangping
    Liao, Taohong
    Fracture mechanics mathematical modelling for Dynamic Stress Intensity Factor of 3-Point Bending Specimen2011Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper emphasizes on the analysis of fracture mechanical characteristics of 3-Point Bending Specimen suffering driving force. By analyzing the structural characteristics of the 3-Point Bending Specimen, the equivalent mathematical model mass-damping-spring system has been formulated. The variation of parameters method is then used to solve the corresponding second order differential equation and find the general analytical formula for the Dynamic Stress Intensity Factor. This analytical formula for Dynamic Stress Intensity Factor will be useful for the further researches and practical engineering design and applications in fracture mechanical field

  • 155.
    Hyder, Mohammed Jalaluddin
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Ahmed, Hameeduddin
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    A Pre-Study of the Tearing Behaviour of the Flexible Materials-towards Efficiency Packaging2006Independent thesis Advanced level (degree of Master (One Year))Oppgave
    Abstract [en]

    In this thesis the tearing behaviour of flexible material is studied. A finite element model was built in ABAQUS and simulations were performed. The experimental tests were carried out to monitor the Load vs. Extension curve on single-tear specimen of Low Density Polyethylene (LDPE) and Paperboard. The simulation results were compared with the experimental results and observed to have good agreement between them

  • 156.
    Igweokpala, Chinenye
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Umegboro, Onyema
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Analysis of the Behaviour of Standing Acoustic Waves in a Cubically Nonlinear Medium.2007Independent thesis Advanced level (degree of Master (One Year))Oppgave
    Abstract [en]

    The basic distinction between linear and nonlinear acoustics is given in the introductory part. The differences between nonlinear acoustic waves in quadratic and cubic media are briefly explained. The behavior of standing waves, including the wave profile evolution, is described. A perturbation analysis leading to the wave profile for a standing wave in a cubic medium is presented. Finally, interpretation of the solutions containing shock waves and verification of the matching of the inner and the outer solutions through an intermediate solution at the regions containing shock fronts are made. The plots were generated using MATLAB.

  • 157. Ilic, Danica Djuric
    et al.
    Dotzauer, Erik
    Trygg, Louise
    Broman, Göran
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Integration of biofuel production into district heating - part I: an evaluation of biofuel production costs using four types of biofuel production plants as case studies2014Inngår i: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 69, s. 176-187Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper evaluates the effects on profitability of biofuel production if biofuel producers would sell the waste heat from the production to a local district heating system. All analyses have been performed considering four different technology cases for biofuel production. Two technology cases include ethanol production which is followed by by-production of raw biogas. This biogas can be upgraded and sold as biofuel (the first technology case) or directly used for combined heat and power production (the second technology case). The third and the fourth technology cases are Fischer-Tropsch diesel and dimethyl ether production plants based on biomass gasification. Two different district heating price levels and two different future energy market scenarios were considered. The sensitivity analyses of the discount rate were performed as well. In the case of energy market conditions, the profitability depends above all on the price ratio between biomass (used as the feedstock for biofuel production) and crude oil (used as the feedstock for fossil diesel and gasoline production). The reason for this is that the gate biofuel prices (the prices on which the biofuel would be sold) were calculated assuming that the final prices at the filling stations are the same as the prices of the replaced fossil fuel. The price ratios between biomass and district heating, and between biomass and electricity, also have an influence on the profitability, since higher district heating and electricity prices lead to higher revenues from the heat/electricity by-produced. Due to high biofuel (ethanol + biogas) efficiency, the ethanol production plant which produces upgraded biogas has the lowest biofuel production costs. Those costs would be lower than the biofuel gate prices even if the support for transportation fuel produced from renewable energy sources were not included. If the raw biogas that is by-produced would instead be used directly for combined heat and power production, the revenues from the electricity and heat would increase, but at the same time the biofuel efficiency would be lower, which would lead to higher production costs. On the other hand, due to the fact that it has the highest heat efficiency compared to the other technologies, the ethanol production in this plant shows a high sensitivity to the district heating price level, and the economic benefit from introducing such a plant into a district heating system is most obvious. Assuming a low discount rate (6%), the introduction of such a plant into a district heating system would lead to between 28% and 52% (depending on the district heating price level and energy market scenario) lower biofuel production costs. Due to the lower revenues from the heat and electricity co-produced, and higher capital investments compared to the ethanol production plants, Fischer-Tropsch diesel and dimethyl ether productions are shown to be profitable only if high support for transportation fuel produced from renewable energy sources is included.

  • 158.
    Iqbal, Muhammed Shahid
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Muhammedi, Abdul Baseer
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Tearing Fracture & Microscopic Analysis of Laminate- Towards Sustainable Packaging2007Independent thesis Advanced level (degree of Master (One Year))Oppgave
    Abstract [en]

    This thesis takes an insight look into tearing behaviour of thin materials used in food packaging. The investigation was based on 2-leg trousers-tear specimen with constant pre-crack length. The materials used in this work were al-foil and a laminate composed of paperboard, low-density polyethylene and al-foil. Theory of Essential work, experimental and finite element methods were used for analysis. Microscopic study was performed to analyse the crack behaviour for both materials and comparison was made. Microscopic photographs show the actual condition of the crack; these photographs were put together with corresponding experimental data. It provided an effective method to analyse the fluctuations in the data compared with actual crack condition. A simple finite element model was made in order to show the stress distribution around the crack tip. It was found that the tearing behaviour is a combination of mode I and mode III fracture. Commercial software ABAQUS was used for finite element modelling. Crack propagation was not considered during simulation

  • 159. Isaksson, Ola
    et al.
    Kossman, Mario
    Bertoni, Marco
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Eres, Hakki
    Monceaux, Anne
    Bertoni, Alessandro
    Wiseall, Steve
    Zhang, Xinwei
    Value-­Driven Design -­ A methodology to Link Expectations to Technical Requirements in the Extended Enterprise2013Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Current systems engineering (SE) standards do not address ‘Value’ in much detail. Yet, understanding what drives the generation of stakeholder value in a given business context, is fundamental to promoting a common and clear vision throughout the extended enterprise, of what should be the focus of their early, conceptual work at all levels of development. This paper presents a Value-Driven Design (VDD) methodology designed to strengthen the value and requirements maturation process within an extended enterprise setting. The work presented is the result of a three and a half year European program (CRESCENDO) within the aerospace sector. The VDD methodology is introduced and explained in an industrial aircraft development context and a selection of enabling methods and tools associated to the VDD methodology is presented.

  • 160.
    Islam, Md. Shafiqul
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Kao-Walter, Sharon
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Chen, Xin
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Deng, Hong Yu
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Innovation for and by the People with Disabilities: A Case Study in Improvement of the Manual Wheelchair2013Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper focuses on information-driven engineering, where information is gathered by means of innovation for people and by the people. This case study was carried out on innovation of a manual wheelchair. Through active participation of person with disability (direct users) and their carers (indirect user), knowledge awareness of the early design was increased. Computer aided engineering tools were used for the development of virtual prototype (VP) and after further feedback from direct and indirect users design was adjusted. Additionally, Physical prototype was built to practically demonstrate the new features to users and finally the prototype was readjusted to bridge user requirement even more. This innovation process identifies additional improvement aspects and contributes beyond fundamental personal needs and increases well being.

  • 161.
    JingJing, Duan
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Xinze, Li
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Sitch, Renate
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Ethical Consumers:Strategically Moving the Restaurant Industry towards Sustainability2008Independent thesis Advanced level (degree of Master (One Year))Oppgave
    Abstract [en]

    Consumerism plays an important role in the development of society, and consumption can be a driving force to shift society into a sustainable future. This paper defines ethical consumers and the restaurant industry as the research field, after analysing the current reality of restaurant industry, and the existing tools for ethical consumers to make their purchasing decision, we bridge the gaps by creating an ideal eco-labelling process for the restaurant industry. Eco-Etiquette is our ideal sustainable tool to better inform ethical consumers in their purchasing decisions. This paper also discusses other ways to assist ethical consumers, and identify some aspects for further research.

  • 162.
    Jonasson, Anna
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Kneppers, Ben
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Moore, Brendan
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Principles-Based Comparison Framework for Renewable Electricity Options2008Independent thesis Advanced level (degree of Master (One Year))Oppgave
    Abstract [en]

    Electricity generation is both a major contributor to the root causes of environmental unsustainability and an energy source that will likely play an important role in the transition to a sustainable society. Because renewable sources of electricity generation are seen as sustainable as a group, there is a danger that investments will be made in renewable technologies that do not effectively move society towards sustainability. We propose the use of a scientific, principles-based definition of sustainability to compare current and future renewable electricity options on their sustainability potential. This study presents a pilot decision-support comparison tool, Guide for Sustainable Energy Decisions (GSED), designed to give investors, policy makers, and manufacturers strategic guidance on the most effective renewable technologies to invest in for sustainability. The tool is based on a modified version of life cycle assessment (LCA) that allows comparisons of the upstream and downstream effects of generation technologies from a whole-systems sustainability perspective. Early feedback by experts suggests that the tool has strong potential to serve as an effective comparison tool and help decision-makers make strategic investments for sustainability.

  • 163. Josefsson, Andreas
    Identification and Simulation Methods for Nonlinear Mechanical Systems Subjected to Stochastic Excitation2011Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    With an ongoing desire to improve product performance, in combination with the continuously growing complexity of engineering structures, there is a need for well-tested and reliable engineering tools that can aid the decision making and facilitate an efficient and effective product development. The technical assessment of the dynamic characteristics of mechanical systems often relies on linear analysis techniques which are well developed and generally accepted. However, sometimes the errors due to linearization are too large to be acceptable, making it necessary to take nonlinear effects into account. Many existing analysis techniques for nonlinear mechanical systems build on the assumption that the input excitation of the system is periodic and deterministic. This often results in highly inefficient analysis procedures when nonlinear mechanical systems are studied in a non-deterministic environment where the excitation of the system is stochastic. The aim of this thesis is to develop and validate new efficient analysis methods for the theoretical and experimental study of nonlinear mechanical systems under stochastic excitation, with emphasis on two specific problem areas; forced response simulation and system identification from measurement data. A fundamental concept in the presented methodology is to model the nonlinearities as external forces acting on an underlying linear system, and thereby making it possible to use much of the linear theories for simulation and identification. The developed simulation methods utilize a digital filter to achieve a stable and condensed representation of the linear subparts of the system which is then solved recursively at each time step together with the counteracting nonlinear forces. The result is computationally efficient simulation routines, which are particularly suitable for performance predictions when the input excitation consist of long segments of discrete data representing a realization of the stochastic excitation of the system. Similarly, the presented identification methods take advantage of linear Multiple-Input-Multiple-Output theories for random data by using the measured responses to create artificial inputs which can separate the linear system from the nonlinear parameters. The developed methods have been tested with extensive numerical simulations and with experimental test rigs with promising results. Furthermore, an industrial case study of a wave energy converter, with nonlinear characteristics, has been carried out and an analysis procedure capable of evaluating the performance of the system in non-deterministic ocean waves is presented.

  • 164.
    Josefsson, Andreas
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Ahlin, Kjell
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Broman, Göran
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Bias errors due to leakage effects when estimating frequency response functions2012Inngår i: Shock and Vibration, ISSN 1070-9622, E-ISSN 1875-9203, Vol. 19, nr 6, s. 1257-1266Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Frequency response functions are often utilized to characterize a system's dynamic response. For a wide range of engineering applications, it is desirable to determine frequency response functions for a system under stochastic excitation. In practice, the measurement data is contaminated by noise and some form of averaging is needed in order to obtain a consistent estimator. With Welch's method, the discrete Fourier transform is used and the data is segmented into smaller blocks so that averaging can be performed when estimating the spectrum. However, this segmentation introduces leakage effects. As a result, the estimated frequency response function suffers from both systematic (bias) and random errors due to leakage. In this paper the bias error in the H_1 and H_2-estimate is studied and a new method is proposed to derive an approximate expression for the relative bias error at the resonance frequency with different window functions. The method is based on using a sum of real exponentials to describe the window's deterministic autocorrelation function. Simple expressions are derived for a rectangular window and a Hanning window. The theoretical expressions are verified with numerical simulations and a very good agreement is found between the results from the proposed bias expressions and the empirical results.

  • 165. Josefsson, Andreas
    et al.
    Berghuvud, Ansel
    Ahlin, Kjell
    Broman, Göran
    Performance of a Wave Energy Converter with Mechanical Energy Smoothing2011Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A wave energy converter which uses a power balancing mechanism for turning intermittent and irregular wave motion input to smoothed continuous electrical power output is studied by combined scale-model testing and numerical simulation. The studied concept consists of a moored floating device together with a moving mass which is used to store instantaneous incoming power and deliver a controllable load to an electric generator over a unidirectional rotating shaft. A mathematical model describing the vertical dynamics of the wave energy converter is presented. The wave-body interaction is modelled with linear potential theory and a nonlinear rigid-body model describes the power take-off system. Experimental data from a scale-model test is utilized to validate and update the linear hydrodynamic model. A simulation study is then carried out in order to investigate the performance characteristics of the coupled hydrodynamic and mechanical system. An efficient time-domain algorithm is developed in order to simulate the discontinuous nonlinear characteristics of the combined system in non-deterministic wave situations. The simulation result provides a prediction of the absorbed power and capture ratio which can be used to evaluate the performance in different wave situations. The developed analysis procedure demonstrates its capability to produce computationally efficient performance predictions suitable for design evaluation and optimisation.

  • 166. Josefsson, Andreas
    et al.
    Magnevall, Martin
    Ahlin, Kjell
    Control Algorithm For Sine Excitation On Nonlinear Systems2006Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    When using electrodynamic vibration exciters to excite structures, the actual force applied to the structure under test is the reaction force between the exciter and the structure. The magnitude and phase of the reaction force is dependent upon the characteristics of the structure and exciter. Therefore the quality of the reaction force i.e. the force applied on the structure depends on the relationship between the exciter and structure under test. Looking at the signal from the force transducer when exciting a structure with a sine wave, the signal will appear harmonically distorted within the regions of the resonance frequencies. This phenomenon is easily observed when performing tests on lightly damped structures. The harmonic distortion is a result of nonlinearities produced by the shaker when undergoing large amplitude vibrations, at resonances. When dealing with non-linear structures, it is of great importance to be able to keep a constant force level as well as a non-distorted sine wave in order to get reliable results within the regions of the resonance frequencies. This paper presents theoretical methods that can be used to create a non-distorted sinusoidal excitation signal with constant force level.

  • 167. Josefsson, Andreas
    et al.
    Magnevall, Martin
    Ahlin, Kjell
    On Nonlinear Parameter Estimation with Random Noise Signals2007Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In the field of nonlinear dynamics it is essential to have well tested and reliable tools for estimating the nonlinear parameters from measurement data. This paper presents an identification technique based on using random noise signals, as initially developed by Julius S. Bendat. With this method the nonlinearity is treated as a feedback forcing term acting on an underlying linear system. The parameter estimation is then performed in the frequency domain by using conventional MISO/MIMO techniques. To apply this method successfully it is necessary to have some pre-information about the model structure and thus methods for nonlinear characterization and localization are studied. The paper also demonstrates the various ways the method can be formulated for multiple-degree-of-freedoms. The implementation of the method is illustrated with simulated data as well as a practical application, where the method is used to create a dynamic model of a test-rig with a significant nonlinearity.

  • 168.
    Josefsson, Andreas
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Magnevall, Martin
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Ahlin, Kjell
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Broman, Göran
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Spatial location identification of structural nonlinearities from random data2012Inngår i: Mechanical systems and signal processing, ISSN 0888-3270, E-ISSN 1096-1216, Vol. 27, nr 1, s. 410-418Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    With growing demands on product performance and growing complexity of engineering structures, efficient tools for analyzing their dynamic behavior are essential. Linear techniques are well developed and often utilized. However, sometimes the errors due to linearization are too large to be acceptable, making it necessary to take nonlinear effects into account. In many practical applications it is common and reasonable to assume that the nonlinearities are highly local and thus only affect a limited set of spatial coordinates. The purpose of this paper is to present an approach to finding the spatial location of nonlinearities from measurement data, as this may not always be known beforehand. This information can be used to separate the underlying linear system from the nonlinear parts and create mathematical models for efficient parameter estimation and simulation. The presented approach builds on the reverse-path methodology and utilizes the coherence functions to determine the location of nonlinear elements. A systematic search with Multiple Input/Single Output models is conducted in order to find the nonlinear functions that best describe the nonlinear restoring forces. The obtained results indicate that the presented approach works well for identifying the location of local nonlinearities in structures. It is verified by simulation data from a cantilever beam model with two local nonlinearities and experimental data from a T-beam experimental set-up with a single local nonlinearity. A possible drawback is that a relatively large amount of data is needed. Advantages of the approach are that it only needs a single excitation point that response data at varying force amplitudes is not needed and that no prior information about the underlying linear system is needed.

  • 169. Jönsson, Anders
    Lean Prototyping of Multi-body and Mechatronic Systems2004Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Major drivers behind increased efforts in product development are the increased competition due to globalisation and the urgent transformation of society towards sustainability. Furthermore, the average product lifetime has been compressed significantly over the last decade. Due to these trends, there is increasing demand for an efficient product development process. Cutting time-to-market, reducing costs and increasing quality are widely accepted as key factors to successful product development. Consideration of sustainability aspects in product development is also becoming increasingly important. Methods and tools that are useful also for small and medium sized enterprises are of particular importance for the Swedish industry. This thesis suggests a definition of lean prototyping and points to its potential for supporting efficient product development. This is done through two case studies: a soil compactor machine treated as a multi-body system and a water jet cutting machine treated as a mechatronic system. Lean prototyping is defined as a coordinated approach to experimentation with the purpose of achieving cost-efficient and accurate enough prediction of product characteristics to support optimisation and well-informed design decisions during product development, especially in the early stages. This often involves an iterative search for and use of a suitable combination of virtual and limited physical prototypes as well as the reuse of knowledge from previous projects. The case studies are performed in cooperation with one small and one medium sized company, indicating the usefulness of the approach for different product types as well as for different company sizes. More specifically, the validated multi-body model of the soil compactor machine describes the dynamics of the machine satisfactorily and the optimisation study shows a significant potential for improved compaction capacity. This potential would not likely been found through traditional physical prototyping. The related comparative study of contact transition conditions is a contribution to consistent impact modelling in multi-body dynamics in general. The real-time virtual machine concept for simulation of the water jet cutting machine, including detailed mechanical component models, is unique. The fully automated concept implementation makes it a promising base for multidisciplinary design optimisation of the water jet cutting machine, and probably of mechatronic products in general.

  • 170. Jönsson, Anders
    et al.
    Broman, Göran
    Bathelt, Jens
    Implications of modelling one-dimensional impact by using a spring and damper element2005Inngår i: Proceedings of the Institution of mechanical engineers. Proceedings part K, journal of multi-body dynamics, ISSN 1464-4193, E-ISSN 2041-3068, Vol. 219, nr 7, s. 299-305Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A spring and damper contact force element is often used for modelling impact in multi-body dynamics. The related condition for transition between contact and non-contact is, however, inconsistently implemented in the literature and commercial software. This comparative study aims to clarify the implications of four commonly used transition conditions. Principal differences are discussed and, by simulation of a typical system, it is shown that there are significant differences in the dynamics of the system depending on the different conditions. Two of them give unrealistic contact forces and should imply incorrect prediction of system dynamics in most applications. This suggests that it is important to review results obtained from using these conditions and to eliminate them from commercial software. A discussion of the two other conditions culminates in a recommendation.

  • 171. Jönsson, Anders
    et al.
    Wall, Johan
    Broman, Göran
    A Virtual Machine Concept for Real-Time Simulation of Machine Tool Dynamics2005Inngår i: International journal of machine tools & manufacture, ISSN 0890-6955, E-ISSN 1879-2170, Vol. 45, nr 7, s. 795-801Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    When designing CNC machine tools it is important to consider the dynamics of the control, the electrical components and the mechanical structure of the machine simultaneously. This paper describes the structure and implementation of a concept for real-time simulation of such machine tools using a water jet cutting machine as an application. The concept includes a real control system, simulation models of the dynamics of the machine and a virtual reality model for visualisation. The real-time capability of the concept, including the simulation of electrical and rather detailed mechanical component models is proofed. The validation process indicates good agreement between simulation and measurement, but suggests further studies on servo motor, connection and flexibility modelling. However, already from the initial simulation results presented in this paper it can be concluded that the influence of structural flexibility on manufacturing accuracy is of importance at desired feeding rates and accelerations. The fully automated implementation developed in this work is a promising base for dealing with this trade-off between productivity and accuracy of the manufacturing process through multidisciplinary optimisation.

  • 172. Kamakura, Tomoo
    et al.
    Nomura, Hideyuki
    Akiyama, Masahiko
    Hedberg, Claes
    Parametric Sound Fields Formed by Phase-inversion Excitation of Primary Waves2011Inngår i: Acta Acustica united with Acustica, ISSN 1610-1928 , Vol. 97, nr 2, s. 209-218Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Two planar ultrasound pro jectors having identical rectangular apertures were placed side by side. Both pro jectors radiated bifrequency primary waves in air. The frequencies were 26 and 28 kHz, and the initial phases were different. Two driving modes were considered, namely, conventional in-phase driving and phase-inversion driving. The spatial profiles of sound pressure fields were measured along and across the sound beam axis for the primary waves and a difference in frequency waves of 2 kHz. The second and third harmonic components of the difference frequency waves were also measured. The pressure levels of the primary waves were considerably suppressed near the beam axis owing to phase cancellation when the driving signals were phase-inversed, i.e., 180 degrees out of phase. The beam pattern of the difference frequency was, however, almost the same as that for the case in which the signals were in phase. Interestingly, the harmonic pressure amplitudes of the difference frequency were reduced by more than 10 dB. The validity of the experimental results were confirmed based on their good agreement with the theoretical predictions based on the Khokhlov-Zabolotskaya-Kuznetsov equation.

  • 173.
    Kandge, Ganesh M
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Influence of Mode Dependent Rayleigh Damping on Transient Stress Response2007Independent thesis Advanced level (degree of Master (One Year))Oppgave
    Abstract [en]

    Main task of thesis is to study the effect of Mode dependent Rayleigh damping on System response. Damping ratio for the structure is not constant for all modes and it varies mode wise. In present task different damping models are defined and used to obtain responses for transient system. Obtained responses show that there is considerable effect of mode dependent damping on response of the system. This outcome could be used for investigations of noise, harshness and fatigue.

  • 174. Kao-Walter, Sharon
    On the Fracture of Thin Laminates2004Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis concerns mechanical and fracture properties of a thin aluminium foil and polymer laminate that is widely used as packaging material. The possibility of controlling the path of the growing crack propagation by adjustment of the adhesion level and the property of the polymer layer is investigated. First, the fracture process of the aluminium foil is investigated experimentally. It is found that fracture occurs at a much lower load than what is suggested by standard handbook fracture toughness. Observations in a scanning electron microscope with a tensile stage show that small-scale stable crack growth occurs before the stress intensity factor reaches its maximum. An examination using an optical profilometric method shows almost no plastic deformation except for in a small necking region at the crack tip. However, accurate predictions of the maximum load are obtained using a strip yield model with a geometric correction. Secondly, the mechanical and fracture properties of the laminate are studied. A theory for the mechanics of the composite material is used to evaluate a series of experiments. Each of the layers forming the laminate is first tested separately. The results are analysed and compared with the test results of the entire laminate with varied adhesion. The results show that tensile strength and strain at peak stress of the laminate, with or without a crack, increase when the adhesion of the adhesive increases. It is also found that a much larger amount of energy is consumed in the laminated material at tension compare with the single layers. Possible explanations for the much higher toughness of the laminate are discussed. Finally, the behaviour of a crack in one of the layers, perpendicular to the bimaterial interface in a finite solid, is studied by formulating a dislocation superposition method. The stress field is investigated in detail and a so-called T stress effect is considered. Furthermore, the crack tip driving forces are computed numerically. The results show that the analytical methods for an asymptotically small crack extension can also be applied for a fairly large amount of crack growth. By comparing the crack tip driving force of the crack deflected into the interface with that of the crack penetrating into the polymer layer, it is shown how the path of the crack can be controlled by selecting a proper adhesion level of the interface for different material combinations of the laminate.

  • 175.
    Kao-Walter, Sharon
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Andreasson, Eskil
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Ståhle, Per
    Micro-mechanism of Thin and Laminated Packaging Material during Fracture2012Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Fracture path of a polymer coated and uncoated aluminium foil (about 6-7 um) is followed in a Scanning Electron Microscope. The crack length and applied load were measured during crack initiation and growth. The specimens’ cross section were then studied using the optical profilometric method to exam the deformed surface. For the uncoated Al-foil, no fracture surface can be observed. Fracture seems to occur through so-called necking. This behaviour was successfully modelled by a modified strip yield model. It leads to a conclusion that the crack tip is preceded a substantial plastic zone as compared with the crack length. The result was then compared to a polymer coated Al-foil. Further more, similar experimental works were performed on a polymer coated and uncoated Polypropylene. The results were discussed and compared to the cases with Al-foil layer.

  • 176. Kao-Walter, Sharon
    et al.
    Dahlström, J.
    Karlsson, T.
    Magnusson, A.
    A study of the relation between mechanical properties and adhesion level in a laminated packaging material2004Inngår i: Mechanics of composite materials, ISSN 0191-5665, E-ISSN 1573-8922, Vol. 40, nr 1, s. 29-36Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The mechanical properties of a laminate consisting of aluminum-foil, adhesive, and polymer layers were studied in relation to the adhesion level. A special application for liquid-food packaging materials was considered. In experiments, laminates with and without adhesive layers were tested. Tensile tests were first run for every layer of the laminate, and the data obtained were then used in analyzing the results of tensile tests on the entire laminate, as well as in theoretical and finite-element calculations. Relations between different mechanical properties (such as Young's modulus, the peak stress, and the strain at the peak stress) and the adhesion level were analyzed. It was found that the tensile strength and the strain at the peak stress increased with adhesion level. Only slight differences in Young's modulus were observed at different adhesion levels.

  • 177.
    Kao-Walter, Sharon
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Hu, Min
    Walter, Mats
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Leon, Armando
    A Comparison of 2-zone and 3-zone Models in Tearing based on Essential Work of Fracture2009Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Two different models (2-zone and 3-zone) for describing the deformation and fracture behavior of tearing ligament was compared and discussed based on the experimental results made by Kim et al. The models are based on the Essential Work of Fracture approach for predicting the specific total work of fracture along the tear path across plastic zones. The experiment and analysis were based on 2-leg trousers tear specimen. The materials chosen in this work were PET (0.508 mm). The results showed that the accuracy of 3-zone model was higher than 2-zone model. It was found that this difference is because the 2-zone model did not consider the plastic deformation caused by loading prior to tearing. Also a finite element model was created to simulate the behavior around the crack tip.

  • 178. Kao-Walter, Sharon
    et al.
    Huang, Yayu
    From Friendship Provinces to University Teacher/Student Exchange2009Konferansepaper (Annet (populærvitenskap, debatt, mm))
    Abstract [en]

    The establishment of the province friendship between Blekinge (Sweden) and Yunnan (China) has lead to a coperation agreement between two local Universities: Blekinge Institute of Technology and Kunming University of Science and Technology. It leads to the development of the cooperation of two provices in the fields of culture, business and education.

  • 179. Kao-Walter, Sharon
    et al.
    Levin, M.L.
    Petronyuk, J.S.
    Walter, Mats
    Acoustic imaging internal microstructure of a packaging material2008Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Microstructure of a paper-based packaging material was studied by acoustic microscopy method. The laminate structure of the packaging material contains paperboard, polymer and aluminium, which are widely used for aseptic liquid food package. The method has also been used to detect delaminations inside the material. The results show the possibility to study the micro structural features of paperboard, polymer and aluminium foil layered materials by applying the high-resolution ultrasonic acoustic microscopy. The potential for visualization defects in the body of this kind of materials is discussed in order to further develop the Non-Destructive Testing (NDT) method in food packaging industries.

  • 180. Kao-Walter, Sharon
    et al.
    Mfoumou, Etienne
    Laksman, Efraim
    Stress Relaxation of a Paper Sheet under Cyclic Load: An Experimental and Theoretical Model2010Inngår i: Materials Sciences and Applications, ISSN 2153-117X, E-ISSN 2153-1188, Vol. 1, nr 6, s. 317-322Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Mechanical experiments have been performed to study the dynamic stress relaxation of a paper sheet material mainly used in food packaging industry. The material was cyclically tensile-loaded with a strain range between 2.4% and 4%. The time period for each cycle was 400 seconds. It was found that stress will decrease when the number of cycles increases in the case of upper load and vice versa in the case of lower load. At the same time, the stress to strain curves followed the same pattern as the one from the previous cycle. The stress relaxation behavior of each cycle has been analyzed and the dynamic relaxation modulus was derived. An improved model is proposed to describe the dynamic relaxation behavior of the paper sheet. This model shows a very good fit to the experimental results and trends of prediction are observed. Furthermore, the physical description of this model and the variation by the cycles is discussed.

  • 181.
    Kao-Walter, Sharon
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Mfoumou, Etienne
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Ndikontar, Maurice
    Mechanical Properties and Life-Cycle Sustainability Aspects of Natural Fibre2012Inngår i: Advanced Materials Research, TRANS TECH PUBLICATIONS LTD , 2012, Vol. 347-353, nr Part 1-7, s. 1887-1893Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In order to understand the basic definition of the natural material, references of recently published articles were studied. From these articles, the definition of different terms like renewable material, recyclable material, biodegradable material, sustainable material and finally natural material were collected. Furthermore, a classification of natural fibre was drawn. One of these natural fibres - the coconut was chosen for a more detail analysis in mechanical point of view. An integrated method to analyse the sustainability of the coconut fibre as one of the blend components in building construction will be suggested. Finally, several uses of the fibre are reviewed.

  • 182. Kao-Walter, Sharon
    et al.
    Ståhle, Per
    Chen, S.H.
    A Finite Element Analysis of a Crack Penetrating or Deflecting into an Interface in a Thin Laminate2006Inngår i: Key Engineering Materials, ISSN 1013-9826, E-ISSN 1662-9795, Vol. 312, s. 173-178Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The crack tip driving force of a crack growing from a pre-crack that is perpendicular to and terminating at an interface between two materials is investigated using a linear fracture mechanics theory. The analysis is performed both for a crack penetrating the interface, growing straight ahead, and for a crack deflecting into the interface. The results from finite element calculations are compared with asymptotic solutions for infinitesimally small crack extensions. The solution is found to be accurate even for fairly large amounts of crack growth. Further, by comparing the crack tip driving force of the deflected crack with that of the penetrating crack, it is shown how to control the path of the crack by choosing the adhesion of the interface relative to the material toughness.

  • 183. Kao-Walter, Sharon
    et al.
    Tryding, Johan
    Fracture mechanics of materials: From steel to packaging material2007Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The application of fracture mechanics started during the 20th century. By natural reason, most of the early research has been related to e.g. construction and defence industries. The fracture mechanics theories have been developed based on materials used by these industries, e.g. metals, plastic, concrete and soil materials. Later, along with the development of composite materials (and now even nano-materials), fracture mechanics theory was extended to include the fracture behaviour in composite materials. Nowadays, packaging industries utilize the fracture theories to enhance the package quality and cut the costs. Paper based packages for liquid food in ambient climate have been built up by the combination of paper, plastic and aluminium-foil. Research in this area has been done by the authors. It is found that many fracture related problems that occurs in the making of liquid food packages can be analyzed by the theory of fracture mechanics. However, it is the authors experience that to fully understand the interaction of the materials leading to fracture in the package laminate, further research in fracture of laminate is needed.

  • 184. Kao-Walter, Sharon
    et al.
    Walter, Mats
    Dasari, A
    Leon, Armando
    Tearing and Delaminating of a Polymer Laminate2011Inngår i: Key Engineering Materials, ISSN 1013-9826 , Vol. 465 , s. 169-174Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The fracture behaviour of laminated materials was studied in this work. The materials used in this work were low-density polyethylene (LDPE) laminated on polyethylene (PET). The thickness of the LDPE was 27 μm and the PET was 100 μm. Experiments were performed by using a 2-leg trousers specimen to analyse the tearing behaviour of the laminate in relation to the delamination. A clear delamination zone was observed during the crack propagation by tearing. Furthermore, a finite element calculation was performed to simulate the behavior around the crack tip during the tearing. A correlation between adhesion and crack propagation was discussed. Finally, the theory of Essential Work of Fracture (EWF) was used for predicting the specific total work of fracture along the tear path across the plastic zones.

  • 185. Kao-Walter, Sharon
    et al.
    Walter, Mats
    Muhammadi, A.B.
    Tensile and Tearing Fracture Behaviour of Food Packaging Laminate2007Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Fracture behaviour of laminated food packaging materials is studied. The materials used in this work were the single layer of Aluminium foil (Al-foil), Low density polyethylene (LDPE) and the lamination of these single layers. Experiments were performed by applying the centred crack specimen as well as the 2-leg trousers specimen. It was observed that the load carrying capacity increased for the tensile and decreased for the tearing specimen when the two layers are laminated together. It was also found that in the case of tearing the crack growth was not only initiated by shear stress but also by normal stress. A modified strip yield model and the essential work of fracture theory were used to analyze the deformation and the fracture behaviour. The initial crack growth of the single layers and the laminate during the tensile and tearing were compared and investigated.

  • 186.
    Kao-Walter, Sharon
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    You, Zhong
    Jiang, Xun
    Katangoori, Rahul Reddy
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Stress and Stability Analysis of a Building Column with a Pre-folded Origami Pattern2012Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A tubular structure by applying the pre-folded origami pattern has been developed at the department of Engineering Science, University of Oxford (see Figure 1). Most of the application is in vehicles. For further application possibility in the fields of Building, bridge, Subway or underground structure, stress and stability analysis were performed. Different cases were calculated by theory of instability and Finite Element Method. Different design solutions were introduced and their strength and stability properties were compared by loading the structure with a compression force on the top of the column. The objective of this work is to find a good solution in safety, sustainability and economy point of view. Failure risk due to the eventually pre-crack in structure will also be discussed by the theory of fracture mechanics.

  • 187. Karlsson, Anna
    et al.
    Törlind, Peter
    Johansson, Christian
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Managing Rejected Ideas from Projects— A Way to Avoid Idea Cemeteries2014Konferansepaper (Fagfellevurdert)
    Abstract [en]

    An often neglected topic in idea management research is the continuity and stability of current idea management practices. This study addresses this topic by following a hand-over of ideas from a project to the line organization in a company. Moreover, idea portfolios are proposed and empirically explored as a means of managing and further developing these ideas. This particular idea-capturing scheme is believed to incorporate both codification and personalization approaches in the management of ideas. Twenty-one (21) semi-structured interviews, as well as observations, were conducted during a year, both before and during the implementation of idea portfolios at the company. Results from the study show the importance of considering the recipient of a codification effort in order for codification to become a constructive element rather than a barrier. Another finding is that different stages of maturity and levels of activity should be handled when managing ideas. Therefore, an idea portfolio is something of a hybrid between an idea bank and a register of on-going activities. Managing ideas in a transparent way was also shown to have its pros and cons. Increased transparency can both provide enhanced legitimacy for working with an idea, and increase the accountability of an idea, and can therefore be perceived as an obstacle. Finally, the shared responsibility of an idea that is the consequence of working with an idea portfolio can make the line manager something of an “accomplice”. This in turn helps in propelling the development of the idea forward.

  • 188.
    Katangoori, Rahul Reddy
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Kao-Walter, Sharon
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    You, Zhong
    Conceptual study on an origami patterns of type I tapered square tub with and without a crack2013Inngår i: Applied Mechanics and Materials, Trans Tech Publications, Switzerland , 2013, Vol. 275-277, s. 184-188Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Thin-walled tubes with origami patterns are popular design for the energy observing devices. However, less study has been done when they subjected to cracks. In this work, the origami square tube with different height to wall thickness ratio are first studied to investigate the collapse modes and deformation mode. Further more, stress concentration areas are identified by numerical simulations. Finally, horizontal and vertical crack was implemented in one of the side in order to study the effect on the deformation mode.

  • 189.
    Kazhura, Yury
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Souza, Paulo Bento Maffei de
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Worosz, Heather
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Sustainable Community Development in the Baltic Sea Region2005Independent thesis Advanced level (degree of Master (One Year))Oppgave
    Abstract [en]

    This study examines Sustainable Community Development (SCD) in the context of the Baltic Sea Region. The research focuses on understanding a model for SCD piloted in Robertsfors, Sweden. The model is said to be transferable to any community around the world. This study seeks to understand the concepts and tools used in the Robertsfors Model. It also examines whether the model is strategic with regards to sustainability and whether it is successful in engaging the local community around these issues. Considerations for transferability are also addressed, focusing specifically on the Eastern Baltic Sea Region. Opportunities for improving the model are also studied. A combination of secondary research, in the form of literature review and primary research (structured interviews and questionnaires) was used to explore these questions. Propositions about SCD and questions for further research emerged from this study.

  • 190.
    Kelele, Hailay Kiros
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Analysis of Nonlinear systems with Zero Memory & Determination Limit of Chaos2007Independent thesis Advanced level (degree of Master (One Year))Oppgave
    Abstract [en]

    It is probable that all practical engineering structures are nonlinear to some extent. In this thesis work a two degrees of freedom nonlinear system and experimental structure with zero memory were simulated, modeled and analyzed to understand their behavior for different conditions. Nonlinear parameters and true linear frequency response was extracted. The limit of chaos was also determined. To achieve these results simulation and experimental model was used and analyzed using MATLAB toolbox. This was done using random noise and sweeping sine forces as an input and controlling the amplitude specially when determining the limits of chaos. Good results were achieved and verified combining the simulation and experimental results.

  • 191.
    Kianian, Babak
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Larsson, Tobias
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Tavassoli, Mohammad
    Blekinge Tekniska Högskola, Sektionen för management.
    Manufacturing Renaissance: Return of manufacturing to western countries2013Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Manufacturing Renaissance, i.e. return of manufacturing to west, has been recently observed. This paper analyzes the patterns observed within each of the four main drivers behind this new phenomenon and delves more deeply into the driver that centers on the new manufacturing technologies such as Additive Manufacturing (AM) and 3D Printing. Next, this paper will make the case that the location of manufacturing will be in west, relying on the established theory that has been able to explain the location of manufacturing, i.e. Product Life Cycle Model (PLC).

  • 192.
    Kumar, Dasari Vijay
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Kumar, Palli Kishore
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Study of abnormal combustion oscillations in gas fired appliances2006Independent thesis Advanced level (degree of Master (One Year))Oppgave
    Abstract [en]

    The thesis work discusses abnormal combustion noise in gas-fired appliances. An experimental model was made to provide insight into the causes of abnormal combustion noises. The experimental model was modelled mathematically considering it as a feedback loop system. Finally a stability plot was made to find out at what frequencies the system is stable

  • 193.
    Lamme, Martin
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Larsson, Martin
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Tidäng, Jonas
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Briband: Vattendistribueringssystem2004Independent thesis Basic level (degree of Bachelor)Oppgave
    Abstract [sv]

    Uppdraget som gavs av Brimer VA Produktion AB i Osby var att ”föra fram deras nya vattenledningssystem i ljuset”, göra en FEM-beräkning på en detalj i systemet och ta fram en ekonomisk samt teknisk jämförelse mot det traditionella vattenledningssystemet. Bästa lösningen på uppgiften var att visualisera vattenledningssystemet med hjälp av animerade filmer. Detta med tanke på att visualisering har ingått till stor del i utbildningen Virtuell Produktutveckling & Design.

  • 194. Lebedev-Stepanov, P.V.
    et al.
    Rudenko, Oleg
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Acoustic Flows in a Fluid Layer on a Vibrating Substrate2013Inngår i: Acoustical Physics, ISSN 1063-7710, E-ISSN 1562-6865, Vol. 59, nr 6, s. 640-643Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The field of radiation forces in a fluid layer on a solid substrate is calculated. This field is formed during propagation of surface capillary wave along a free surface. The wave is excited by substrate vibrations as a result of instability development. The structure of acoustic flows is studied. Their effect on small size particles and the possibilities of generating ordered structures from these particles are discussed.

  • 195. Leifer, Larry
    et al.
    Larsson, Andreas
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Larsson, Tobias
    Luleå University of Technology.
    Van der Loos, Machiel
    Feland, John
    Design for wellbeing - innovations for people2005Inngår i: Human Centered Design, Maruzen for 10th anniversary of the Kanto Branch, Japanese Society of Mechanical Engineers , 2005Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    There is a growing need for engineering designers to engage in creative activities that result in innovative products and technologies for the benefit of society. However, from an engineering perspective, issues of ‘life quality’ are currently heavily under-prioritized, particularly with regard to people with disabilities. This paper argues that both needs and solutions are now part of the designer’s responsibility, and that it is crucial to make a qualitative assessment of both the potential market impact and the ‘quality of life’ improvements afforded by innovations. Design for Wellbeing offers a perspective on life quality that goes beyond the traditional scope of assistive technology in that it aims to help people make a transformation from an actual state of being to a desired state of being – regardless of ability level.

  • 196. Leon, Armando
    Non-Linear Vibration and Dynamic Fracture Mechanics of Bridge Cables2011Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    In the present work, the non-linear vibrations and the corresponding dynamic fracture mechanics of cables of cable-stayed bridges are studied. The cables are among the most critical components in cable-stayed bridges and there are different damage sources such as corrosion, vibration, fatigue and fretting fatigue that can significantly affect them, thereby reducing the cable’s service life and even producing their failure. Cable-Parametric Resonance is the specific non-linear vibration studied in this research. This type of vibration occurs due to displacements presented at the cable supports. These displacements are induced by the wind and traffic loads acting on the pylon and deck of the bridge. Under certain conditions, unstable cable-vibration of significant amplitude can be registered. Therefore, numerical and experimental analyses are carried out in order to describe this phenomenon and to determine the corresponding instability conditions. Two non-linear models of cable-parametric resonance are studied to predict the cable response. In the simulation method, the non-linear components are treated as external forces acting on the linear systems, which are represented by Single Degree of Freedom systems and described by digital filters. A clear non-linear relationship between the excitation and the cable response is observed in the simulations and the experiments. The corresponding experimental analysis is based on a scaled model (1:200) of the Öresund bridge and a good agreement between the numerical and experimental results is found. After obtaining the relationship between the cable response and the excitation, the cable instability conditions are determined. This is done by finding the minimum displacement required at the cable supports in order to induce nonlinear cable vibration of considerable amplitude. The instability conditions are determined within a wide range of excitation frequencies and conveniently expressed in a simplified and practical way by a curve. The determination process is rather fast and offers the possibility to evaluate all bridge cable stays in a rather short time. Finally, the dynamic fracture mechanics of the cable is considered by studying the fracture toughness characteristics of the material under dynamic conditions. Finite Element simulations on a pre-cracked three-point bending specimen under impact loading are performed. The observed cable instability is equivalently considered as the associated response to impact load conditions, and a crack as a defect on the wires of a cable stay. The simulations are based on an experimental work by using the Split Hopkinson pressure bar (Jiang et al). The dynamic stress intensity factor KI(t) up to crack initiation is then obtained by different methods. The numerical estimations based on the specimen’s crack tip opening displacement (CTOD) and mid-span displacement were closest to the experimental results. It is observed that a better estimation of the dynamic stress intensity factor relies on a proper formulation of the specimen’s stiffness.

  • 197.
    Leon, Armando
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Ahlin, Kjell
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Kao-Walter, Sharon
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    On Determining Instability Conditions for Stay Cables Subjected to Parametric Resonance2009Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Parametric Resonance Vibration in cables of cable-stayed bridges is mainly studied when the excitation frequency is close to or twice the cable natural frequency. It is, however, important to consider other cases for this frequency relationship, since among other factors, cable-parametric resonance vibrations are strongly depending on the displacement amplitude at the cable supports. Consequently, the present research work is focused on determining, by experimental and numerical analysis, the instability conditions for stay cables subjected to parametric resonance within a wide range of frequency ratios. This is accomplished, by finding the minimum displacement required at the cable supports in order to induce non-linear vibration of considerable amplitude at the cable. Once the cable characteristics (geometry, material properties, inherent damping and initial tensile preload) are known, the instability conditions are identified and expressed in a simplified and practical way in a diagram. Numerical results are compared to those obtained by experimental analysis carried out on a simplified scaled model (1:200) of the Öresund Bridge. A good agreement between numerical and experimental results is found.

  • 198. Leon, Armando
    et al.
    Josefsson, Andreas
    Ahlin, Kjell
    Simulations and Identification of Non-Linear Models for Cables of Cable-Stayed Bridges2010Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Simulations and identification of non-linear parameters are applied on two models that describe the vibration due to parametric resonance in cables of cables-stayed bridges. The aim of this work is to study the dynamic response predicted by the two models under random excitation, as well as to develop a suitable strategy for system identification from random data. In one model the parametric excitation is treated as an arbitrary displacement introduced in one end of the cable. In the second model, such excitation is coming from an external force acting on the pylon or deck of the bridge to which the cable is coupled. The pylon or deck is modeled as a Single Degree of Freedom System. In both models the cable response is obtained by a simulation method based on digital filters. The studied identification technique is based on random excitation. In this method the non-linearity is modeled as a feedback forcing term acting on an underlying linear system or systems and the parameter estimation is performed in the frequency domain by using conventional MI/SO techniques.

  • 199. Lichtenberg, Alexandra
    et al.
    Gurimaraes, Patricia
    Podsedkowska, Heleen
    Planning for Sustainable Mobility with Personal Rapid Transit in Small European Cities2010Konferansepaper (Fagfellevurdert)
  • 200.
    Lichtenberg, Rose
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Guimarães, Patricia
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Podsedkowska, Heleen
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för maskinteknik.
    Personal Rapid Transit systems for reduction in car dependence Karlskrona case study2008Independent thesis Advanced level (degree of Master (One Year))Oppgave
    Abstract [en]

    This research project is designed to enhance the planning process that can aid authorities moving towards sustainable and economically feasible local and regional mobility systems. The improvements that have been made to transit so far have not been successful in breaking the trend of increasing car traffic and decreasing transit trip making. This means that sustainable mobility is a complex system which also encompasses changing attitudes and behaviours, integrating spatial and energy planning into it, and looking upstream to affect the causes of the problem instead of downstream to just fix its consequences. Environmental impacts (noise, pollution, health problems), accidents and congestion are all by-products of transport activities – they are the so-called external costs – and must be made part of the equation. European guidelines were analysed, as well as the results of many of the European Union‘s mobility research programs. The core of the research analyses how to move Karlskrona municipality‘s mobility system towards its vision of success in the future through the Framework for Strategic Sustainable Development – Sustainable Mobility (FSSD-SM). Backcasting from a sustainable vision in the long-term future is central to this process. The Municipality of Karlskrona, in Sweden, is the case study. A sustainability analysis of Personal Rapid Transit (PRT) systems was undertaken to determine the feasability of integrating this modal system into the mobility solution for Karlskrona municipality.

1234567 151 - 200 of 318
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf