Change search
Refine search result
1234567 101 - 150 of 3049
Cite
Citation style
• apa
• ieee
• modern-language-association-8th-edition
• vancouver
• Other style
More styles
Language
• de-DE
• en-GB
• en-US
• fi-FI
• nn-NO
• nn-NB
• sv-SE
• Other locale
More languages
Output format
• html
• text
• asciidoc
• rtf
Rows per page
• 5
• 10
• 20
• 50
• 100
• 250
Sort
• Standard (Relevance)
• Author A-Ö
• Author Ö-A
• Title A-Ö
• Title Ö-A
• Publication type A-Ö
• Publication type Ö-A
• Issued (Oldest first)
• Created (Oldest first)
• Last updated (Oldest first)
• Disputation date (earliest first)
• Disputation date (latest first)
• Standard (Relevance)
• Author A-Ö
• Author Ö-A
• Title A-Ö
• Title Ö-A
• Publication type A-Ö
• Publication type Ö-A
• Issued (Oldest first)
• Created (Oldest first)
• Last updated (Oldest first)
• Disputation date (earliest first)
• Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
• 101.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
Application of the open sourcecode Nemoh for modelling ofadded mass and damping in shipmotion simulations2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis

Two different numerical tools were considered, the first one is a seakeeping method developed by KTH Ship Dynamics Research Program. It utilizes strip theory and Lewis forms and is further addressed as SMS. The second one, Nemoh is an open source code utilizing three-dimensional panel method for calculating first order hydrodynamic coefficients in the frequency domain.A comprehensive revision of Nemoh and SMS has been performed on behalf of the KTH Ship Dynamics Research Program. The background to the revision was the high interest in accurately capturing a ships dynamic response. The aim was to explore the prospect of making use of the open source code Nemoh for modelling of added mass and damping in terms of modelling, computational efforts and ship motion prediction improvements. Further, the thesis includes a well-described method on how to operate and pre-process data for Nemoh together with a validation study including results from commercial software´s and experimental studies. An approach with the aim to capture the speed-dependency of the hydrodynamic coefficients together with further potential development of Nemoh is addressed.The validation of Nemoh is showing diverse result. For two cases, the Response Amplitude in Heave is insufficiently modelled. In consequence it’s stated that further studies are required in order to establish whether it’s the case of inadequate input from the authors’ side or lack of robustness in Nemoh that is the cause. The approach to capture speed effects in the hydrodynamic coefficients is proven to be fairly accurate and is considered to be of further use for future development of Nemoh.With respect to identified computational efforts, it’s concluded that Nemoh requires much more computational time than SMS while the accuracy of result is lower. No major improvements may therefore be achieved by substituting or implementing parts of Nemoh into SMS. Nemoh is however of use for the KTH Ship Dynamics Research Program and of other users of Lewis Method when establishing whether a hull-geometry is considered to be “too” unconventional for a two-parameter mapping technique or not. The capability to calculate the RAO in surge is also of interest for KTH Ship Dynamics Research Program since it’s not a feature in SMS.

• 102.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
Greenhouse gas emissions from rail services: Present and future2010In: Proceedings of Railways and Environment, 2010Conference paper (Refereed)
• 103.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group. KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group. KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
TOSCA. Rail freight transport: Techno-economic analysis of energy and greenhouse gas reductions2011Report (Other academic)

In Stage 1 of the EU/FP7-funded project TOSCA (Technology Opportunities and Strategies toward Climate-friendly trAnsport) the techno-economical feasibility of different technolo-gies and means to reduce greenhouse gas (GHG) emissions is being analysed for different modes of transport. This is made over the long-term perspective until 2050, with 2009 as the reference year. This is the report on the rail freight transport market, applicable to the European Union (EU-27).The analysis presented in this report estimates that a number of efficient technologies and means are available, individually and in combination, to significantly reduce energy use and the resulting GHG emissions on the rail freight market until 2050. The analysis has considered the following technologies and means:

– heavy freight trains (high payload capacity per metre of train as well as longer trains)

– eco-driving, including traffic flow management

– energy recovery

– high-efficiency machinery in locomotives and electric supply

– low air drag

– incremental improvements, in particular reduced tare mass of wagons.

Despite anticipated higher train speeds in most future train operations the above-mentioned technologies and means have, according to the analysis, the potential to reduce the average energy use per net-tonne-km (tkm) of payload by 40–50 % until 2050. As a consequence also the direct and indirect GHG emissions will be reduced. Energy use and GHG emissions are measured per net-tonne-km, assuming representative load factors in different operations.

• 104.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group. KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group. KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
TOSCA. Rail passenger transport: Techno-economic analysis of energy and greenhouse gas reductions2011Report (Other academic)

In Stage 1 of the EU/FP7-funded project TOSCA (Technology Opportunities and Strategies toward Climate-friendly trAnsport) the techno-economical feasibility of different technologies and means to reduce greenhouse gas (GHG) emissions is being analysed for the different modes of transport. This is made in the long-term perspective until 2050, with 2009 as the reference year. This is the report on rail passenger transport, applicable to the European Union (EU-27).The present report has been subject to review among railway experts, representing train suppliers, railway operators as well as academia. They have also responded to a questionnaire. Further, a workshop was held, where the report with assumptions and results was discussed.In the analysis presented in this report it is estimated that a number of efficient improvements that, individually and in combination, are available in order to significantly reduce energy use and the resulting GHG emissions on the rail passenger market until 2050. The analysis has considered different technologies and means:

– low air drag

– low train mass

– energy recovery

– eco-driving, including traffic flow management

– space efficiency in trains (increasing payload per metre of train)

– incremental improvements of energy efficiency, in particular reduced losses.

Despite anticipated higher average train speeds in the future these combined approaches will, according to the analysis, have the potential to reduce the average specific energy use per passenger-km (pkm) in the order of 45–50 % in the very long term until 2050. As a consequ-ence also the direct and indirect GHG emissions will be reduced. The highest reductions are possible in city and regional rail operations. Reductions are more limited in high-speed opera-tions, because of the advanced technologies already applied. However, high-speed rail has today a comparatively low energy use per passenger-km, partly due to its high average load factor. To be consistent with other work packages of TOSCA, energy use and GHG emissions are measured per passenger-km, assuming representative load factors in different operations.

• 105.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group. KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group. KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
Rail Systems and Rail Vehicles: Part 2: Rail Vehicles2016 (ed. 1)Book (Other (popular science, discussion, etc.))

This compendium is mainly intended for MSc education in rail vehicle engineering at KTH Royal Institute of Technology, Stockholm, Sweden. The objective is to give an overview and fundamental knowledge of different rail systems, followed by a more thorough introduction to rail vehicles. In this way most rail aspects are covered. The compendium consists of 20 chapters.

• 106.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering. KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering. KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
On the environmental performance of a high-speed train2014In: International Journal of Rail transportation, ISSN 2324-8378, E-ISSN 2324-8386, Vol. 2, no 1, p. 59-66Article in journal (Refereed)

Environmental performance is one of the major considerations of future high-speed trains. Two main issues have been closely investigated in the Green Train programme, namely (1) energy use and (2) external noise. Analysis, development and testing in the Green Train programme have focused primarily on speeds up to 250 km/h, although the energy issues have also been studied at top speeds up to 320 km/h. The energy use is estimated for both long-distance trains with few stops and for fast regional services with relatively tight underway stops. These estimations result in an energy use of 46–62 Wh per passenger-km – or 30–40 Wh per seat-km – accounted as electricity taken from the public electric power grid. Improved aerodynamic performance, efficient space utilization, electric regenerative brakes, eco-driving advice and improved energy efficiency in the propulsion system make this possible. Trackside noise has also been analysed and tested in the programme. In order to maintain the same or lower noise level at 250 km/h as at lower speeds with current trains, a number of measures are proposed. These include bogie skirts, wheel absorbers and careful aerodynamic design of the front area and of all protruding objects. In sensitive residential areas, further improvement may be achieved with rail absorbers or low trackside screens.

• 107.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport planning, economics and engineering. KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles. Trafikverket. Bombardier Transportation.
Green Train: concept and technology overview2014In: International Journal of Rail Transportation, ISSN 2324-8386, Vol. 2, no 1, p. 2-16Article in journal (Refereed)

Green Train (in Swedish, Gröna Tåget) is a research, development and demonstrationprogramme with the overall objective to define an economical, flexible and environmentallyfriendly train concept. The objective is also to develop technology for futurehigh-speed trains for the northern European market, particularly for Scandinavia. Mostof the technology developed is also applicable to other world markets, as well as toslower trains. The programme has covered many important areas, including economy,capacity and market aspects, conceptual design, traveller attractiveness and interiors,travel time, energy efficiency and noise, winter performance, track friendliness and carbody tilt, aerodynamics, electric propulsion and current collection. The programme hasconducted fundamental analysis and research on the different issues as well as designand testing of new technologies. A number of crucial technologies have undergoneperformance and type testing both in lab and on a test train. Experience feedback wasachieved in commercial train service during the period 2006−2013 including harshwinters. This paper summarises a great deal of research and development that has beenperformed in the Green Train programme.

• 108.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
Energy Consumption and Related Air Pollution for Scandinavian Electric Passenger Trains2006Report (Other academic)

Energy consumption of a number of modern Scandinavian electric passenger train operations is studied. The trains are X 2000, Regina, OTU (Øresundstoget), Type 71 “Flytoget”and Type 73 “Signatur”. Energy measurements are made in regular train operations inSweden, Denmark and Norway. For Regina and Flytoget long time series (at least oneyear) are available, while shorter time series are available for the other train types. Energydata for new trains (introduced since 1999) are collected in the years 2002-2005. Energydata from 1994 are used for X 2000 and are corrected for operational conditions of 2004.For comparison, energy data for an older loco-hauled train of 1994 is also used.In the present study energy consumption for propulsion, on-board comfort and catering, aswell as idling outside scheduled service, is determined. The energy consumption includeslosses in the railway’s electrical supply, i.e. the determined amount of energy is as suppliedfrom the public electrical grid.Emissions of air pollutants, due to production of the electric energy used, are alsodetermined, in this case CO2, NOx, HC and CO. Three alternative determinations are made:(1) Pollution from average electric energy on the common Nordic market;(2) Pollution from “Green” electric energy from renewable sources;(3) Marginal contribution for an additional train or passenger, short-term and long-term.The newly introduced EU Emissions Trading Scheme with emission allowances willmost likely limit the long-term emissions independently of the actual amount ofelectric energy used by electric trains.It is shown that the investigated modern passenger train operations of years 2002- 2005 usea quite modest amount of energy, in spite of the higher speeds compared with trains of1994. For comparable operations the energy consumption is reduced by typically 25 – 30 %per seat-km or per passenger-km if compared with the older loco-hauled trains. The reasonsfor the improved energy performance are:(1) Improved aerodynamics compared with older trains (reduced air drag);(2) Regenerative braking (i.e. energy is recovered when braking the train);(3) Lower train mass per seat;(4) Improved energy efficiency in power supply, partly due to more advancedtechnologies of the trains.Energy consumption per passenger-km is very dependent of the actual load factor (i.e. ratiobetween the number of passenger-km and the offered number of seat-km). For longdistance operations load factors are quite high, typically 55 - 60 % in Scandinavia. In thismarket segment energy consumption is determined to around 0.08 kWh per pass-km. Forfast regional services with electric trains, the load factors vary from typically 20 to about40 %, while the energy consumption varies from 0.07 kWh per pass-km (for the highestload factor) to 0.18 kWh/pass-km.However, also in the latter cases the investigated trains are very competitive to other modesof transport with regard to energy consumption and emissions of air pollutants.

• 109.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
On the Optimization of a Track-Friendly Bogie for High Speed2009In: 21st International Symposium on Dynamics of Vehicles on Roads and Tracks, IAVSD'09, Stockholm, August 17-21, 2009., 2009Conference paper (Other academic)

When designing and optimizing a rail vehicle there is a contradiction between, on the one hand, stability on straight track at high speed and, on the other hand, reasonable wheel and rail wear in small- and medium radius curves. Higher speeds require to some extent stiffer wheelset guidance to avoid hunting and ensure stability. However, with stiffer wheelset guidance the risk of increased wheel and rail wear in curves is imminent. In this paper, the process of developing and optimizing a track-friendly bogie is described. A multi-body system (MBS) simulation model was used, taking due consideration to nonlinearities in suspension and wheel-rail contact, as well as realistic flexibilities in the track. Adequate and systematic consideration is taken to a wide range of possible non-linear wheel-rail combinations. Dynamic stability is investigated both on straight track and in wide curves at high speeds. The balance between flange wear and tread wear is studied in order to maximize wheel life between re-profiling operations in the intended average operation. The result is a bogie with relatively soft wheelset guidance allowing passive radial self-steering, which in combination with appropriate yaw damping ensures stability on straight track at higher speeds. The bogie has been subject to both certification testing and long-term service testing in the Gröna Tåget (the Green Train) research and development programme.

• 110.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles. KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
Radial self-steering bogies - Development, advantages and limitations2007In: ZE Vrail - Glasers Annalen: Zeitschrift fuer das gesamte System Bahn, ISSN 1618-8330, Vol. 131, no Suppl., p. 248-259Article in journal (Refereed)

Considering the total cost of railway operations, It is important to reduce the deterioration caused to the track by rail vehicles and vice versa. Radial steering running gear, where the wheelsets take up approximate radial positions in curves, is an important mean of reducing rail and wheel wear. They also allow curves to be negotiated at higher lateral acceleration on non-perfect track, without exceeding stipulated limits for lateral track shift forces. In order to run dynamically stable at high speed, the damping of the bogie must be appropriate, in particular the yaw damping between bogies and car body. Since the mid-1970's radial self-steering bogles have been developed and used in about 1 200 passenger rail vehicles in Scandinavia. This development continues and during 2006 a test train with radial self-steering bogies is run in speeds up till 281 km/h as part of the Swedish R&D program "GrönaTå get" (GreenTrain). Although there are limitations in the performance of passively self-steering bogles they are a simple and proven solution. Ultimately, In the future actively controlled radial steering may be considered asan appropriate mean to achieve higher performance and track-friendliness.

• 111.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
Radial Self-Steering Bogies: Recent Developments for High Speed2009In: 7th International Conference on Railway Bogies and Running Gears / [ed] István Zobory, 2009, p. 63-72Conference paper (Other academic)

Considering the total cost of railway operations, it is important to reduce the deterioration caused to the track by rail vehicles and vice versa. Radial steering running gear, where the wheelsets take up approximate radial positions in curves, is an important mean of reducing rail and wheel wear. They also allow curves to be negotiated at higher lateral acceleration on non-perfect track, without exceeding stipulated limits for lateral track shift forces. In order to run dynamically stable at high speed, the damping of the bogie must be appropriate, in particular the yaw damping between bogies and carbody. Radial self-steering bogies are used on more than 1200 rail passenger vehicles in Scandinavia since the early 1980’s. The maximum service speed of these vehicles ranges up to 210 km/h. Ongoing development seems to confirm that the use of such bogies can be extended into the very high-speed area of at least 250 km/h. There has previously been some scepticism on the feasibility of soft wheelset guidance for higher speeds, in particular with respect to running stability. Although there are some limitations in the performance of radial self-steering bogies, this solution is robust and well-proven since about 25 years. The ultimate future may be a mechatronic bogie, where the wheelsets are guided in the most optimal way through controlled and forced radial steering. Such bogies may be justified if performance is out of the possible range of passive self-steering solutions.

• 112.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group. KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
Gröna Tåget - Green Train - Train for tomorrow's travellers2011In: ZEVrail, ISSN 1618-8330, Vol. 135, p. 140-153Article in journal (Other academic)

Gröna Tåget (Green Train) is a Swedish research and development programme aiming at defining a concept and developing technology for the next generation high-speed trains, suitable for the Northern European countries. The programme involves almost all major stakeholders in the railway business in Sweden. Main sponsors are Trafikverket (former Banverket) as well as the railway industry and operators (Bombardier, SJ and others). The total budget is around 15 million EUR. The technical coordination is with the Royal Institute of Technology (KTH) in Stockholm. The program started in 2005 and will continue until the end of 2011.

Gröna Tåget is intended to be a fast, track-friendly, electric tilting train that can not only maintain higher speeds than conventional trains on sections with curves, but special versions could allow 300 km/h or more on future dedicated high-speed lines. Gröna Tåget shall be more attractive and more cost effective both to travellers and to operators than today’s trains. Environmental perfor­mance (energy use per passenger, noise) is expected to be still better than existing trains at lower speed.

• 113.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
Models for infrastructure costs related to the wheel-rail interface2009In: Wheel-Rail Interface Handbook, Woodhead Publishing Limited, 2009, p. 608-629Chapter in book (Refereed)

A model for determination of costs for track deterioration is presented. In particular, the model is able to discriminate between vehicles with different characteristics operating on the track, as well as incorporating operating data (speed, cant deficiency, etc.) and track geometry. The model is implemented in an Excel™ environment. Its use is exemplified by a Swedish case of mainline passenger and freight traffic. Some results are presented on the influence of vehicle characteristics, track geometry, track lubrication and speed. The model predicts that axle load, radial steering ability, unsprung mass and track lubrication are decisive for track deterioration and its associated costs.

• 114.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Aerodynamics.
Flödesanalys av befuktarpad: Experiment och simulering2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis

It is well known that the air in an aircraft cabin can be dry and uncomfortable. What is not commonly known is that the human resistants to bacteria and viruses is reduced in this dry air. For long flight the relative humidity inside an aircraft can be reduced to as low as values as 5%, sometimes even lower. This low relative humidity is very extreme and can normaly be found in some deserts. To solve this, the aircraft companies can install humidifiers and raise the relative humidity to more comfortable levels. CTT System has a product which consists of layers of glass fiber sheets which are made wet with a watering system. When the dry air flows through this wet block the water evaporates into the air. This air is then taken to selected parts of the cabin. This project was made to get a deeper understanding of this product. The goal was to investigate two dierent models to simulate the airflow through this humidifier. For this task SOLIDWORKS Flow Simulation was used. It is a commercial Fluid Dynamic solver. To validate the result from the simulation experimental testing have also been done. In the comparison between experimental data and simulated data both pressure drop over the humidifier and velocity profile close after the humidifier have been of interest. The first model is a high detailed CAD version of the humidifier. This model had high demand on mesh quality and the result was time demanding and poor. The second model was a less general model. It constist of a porous block with set properties to match the experimental data. This model had a better prospect and showed a better comparison the experimental data.

• 115.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
Finite Element and Dynamic Stiffness Analysis of Concrete Beam-Plate Junctions2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis

Measurements and predictions of railway-induced vibrations are becoming a necessity in today’s society where land scarcity causes buildings to be put close to railway traffic. The short distances mean an increased risk of the indoor vibration and noise disturbances experienced by residents. In short, the scope of the project is to investigate the transmission loss and vibration level decrease across various junction geometries. The junctions are modelled in both the Finite Element Method (FEM) and the Dynamic Stiffness Method (DSM). Resonances are avoided when possible by using semi-infinite building components.

A two-dimensional model that included Timoshenko beams was set up by Wijkmark [1] and solved using the variational formulation of the DSM by Finnveden [2]. The model is efficient and user-friendly but there is no easy way to adjust the junction geometry since the depths of the walls and the floor slabs are the same. From that study, the current topic was formulated. The results presented in this paper indicate that both the Euler-Bernoulli DS model and the three-dimensional FE model have good potential in describing the vibration transmission across the different junction geometries. The two modelling types show more similar results in the analyses of the bending wave attenuation than in the analyses of the quasilongitudinal wave attenuation. One of the probable causes is that the set length of the Perfectly Matched Layers (PML) is not sufficient at such low frequencies. Larger PMLs require bigger geometries that lead to an increase of the computational time. The other proposed reason is the fact that bending waves are created above the asymmetrical junction when the lower beam is excited by a vertical harmonic force. The flexural displacements are neglected in those cases. The results however, were good enough to be satisfactory. Three junction models were investigated and the attenuation is the highest for both wave types in the case with a beam pair attached to the “middle” of an infinite plate. The attenuation is the second highest across the edge of a semi-infinite plate and the lowest across a junction corner of a semi-infinite plate. As part of the suggested future work, the wave transmission between beam and plate needs to be investigated when Timoshenko beams are included in the DS model. In the Euler-Bernoulli beam theory the cross-section remains perpendicular to the beam axis, which is different to the behaviour of solid elements in FEM.

• 116.
Chalmers, Sweden.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.
Boundary Element Method for Intensity Potential Approach: Predicting the Radiated Sound Power from Partially Enclosed Noise Sources2012In: Acta Acoustica united with Acustica, ISSN 1610-1928, E-ISSN 1861-9959, Vol. 98, no 4, p. 588-599Article in journal (Refereed)

This paper proposes the boundary element method for the intensity potential for prediction of high-frequency sound power flow through partial enclosures. The intensity potential approach is based on the local power balance in a lossless medium and the Helmholtz decomposition of the vector field of time-averaged sound intensity. The result is a Poisson equation for a scalar intensity potential. The intensity potential formulation and the boundary element method are both suitable for exterior problems. The governing equations of the intensity potential and the boundary element method for solving this problem are presented. Results from the proposed method are compared with experimental results, for the case of radiated sound power in one-third-octave bands from sources in a partial enclosure. The results show that the method is applicable for estimation of global radiated sound power in one-third-octave bands in the high-frequency range.

• 117.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
Concept study for cost and weight reduction of a barge container sized module2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis

The intention of this thesis is to develop, evaluate new concepts and look over the current design for a container sized barge module. By request of Group Ocean, a cost and weight reduction is the main improvement criteria along with keeping the strength of the module.Five concepts are developed, analyzed and discussed with the supervisor at Group Ocean, where three are decided to be presented here. The other two are left out, since they are considered way too expensive without giving a satisfying result. The three concepts that are developed throughout this thesis are; changing to high strength steel, changing to sandwich panels and increasing stiffeners with smaller dimensions.A structural optimization is made in the software MATLAB to find out the best dimension to use for the sandwich panels. To determine the local stresses, the finite element method is used in Inventor Professional. It is also where the design and CAD modules are built in, so for simplifications it is used for FEA (Finite Element Analysis) as well. To reduce the amount of elements and nodes, shell elements and other structural constraints are used in the FEA. All the concepts are modelled with the same structural constraints so a practical comparison study can be made.The final designs resulted in a total weight reduction up to 40% with a material cost reduction of 12%. Based on what type of material is chosen, the material cost reduction range is between 3-12% and the weight reduction range is between 13-40%.

• 118.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
Naval ArchitectureRICKY ANDERSSONrickya@kth.se0739-5332522015-06-2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis

På allt senare tid har sjöfarten blivit allt mer eftertraktat och ett nödvändigt transportsätt för att frakta de saker som krävs och önskas av oss människor oavsett var på jorden man är. Det finns många olika sorters av fartyg desginade för olika ändamål som t.ex. roro-fartyg för frakt av fordon, containerfartyg för frakt av containers, bulkfartyg för frakt av olja, kol, malm, trä och passagerarfärjor för frakt och nöjesresor med människor.

Två bulkfartyg har tagits fram för att klara av att frakta 235 000 ton järnmalm(pellets) och har en marschfart på 13,5 knop. Den låga farten gör att kostnaden för frakten kan hållas nere och ändå klara leveransmålet som är 450 000 ton pellets per månad från Narvik, Norge till New York City, USA. Fartyget har slankhetstalet 0,85, vilket nästan motsvarar en fyrkantig låda, allt för att få en stabil gång under färd. Fartyget har en längd på 333 meter och en bred på 57 meter. Motoreffekten för att driva fartyget är 17 000 kW inkluderat en säkerhetsmarginal med 15 % för extremt väder eller tidspress.

Energibehovet i världen är stora och på grund av att de förnyelsebara energikällorna inte räcker till använder man sig av fossila bränslen. Att hitta olja och gas som är ett fossilt bränsle kräver mycket arbete, både i planering samt utrustning. En del av den olja och gas finns offshore och kräver fartyg för transportering och tömning från oljeriggarna men kan också användas för prospektering.

Riskerna är dock väldigt stora i denna bransch och måste tas i största beaktning. Det är dyra investeringar i kampen om att hitta de naturtillgångar som finns kvar. Det har i dagsläget blivit aktuellt att undersöka och prospektera i arktiska områden som är helt outforskat, detta ställer givetvis ännu större krav på utrustning och riskerna ökar.

• 119.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
Utvärdering av infästningar i sandwichkonstruktioner för fordonsapplikationer2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis

The automotive industry is increasingly studying lightweight solution in their designs, also rational production and low costs in materials and manufacturing methods are of great interest. This thesis consisted in the practical evaluation of anchors for sandwich panels. The object was to study loads of shearing and pull out of the plane. The experiments were carried out on panels made up of 1mm aluminium coatings and 50mm extruded polystyrene (XPS) at its core. As the fasteners used simple methods such as blind rivets, screw and glue. 44 tests were performed. Out of these 32 considered pullout of the plane and 12 considered shearing. The results show that it is possible to have good strength in shearing and pull with simple methods.

• 120.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
Pipe-In-Pipe system for offshore applications: Post buckling analysis associated with thermal expansion2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis

The usage of Pipe-In-Pipe (PIP) solutions for offshore applications has increased during the lastyears. The solution gives high thermal insulation and protects the flow line from environmental impacts. One critical load case is buckling of the pipeline system due to thermal expansions of the inner pipe. This project intends to increase knowledge about PIP systems, investigate the impact of different parameters as well as update parameters in an existing SIMLA model. A FE-model of a PIP system was created in ANSYS with a refined section where pipes and centralizers are modelled with solid elements.The ANSYS-model was tested against a verified FE-model created in SIMLA. The global results obtained from ANSYS and SIMLA did not give a perfect match. The ANSYS model tended to buckle in another way, which is assumed to be related to different modelling of resistance between the pipeline and the seabed as well as unwished properties between the side section and the midsection.Local results obtained from ANSYS showed that there are discontinuities in bending moment and effective axial forces when passing a centralizer. The contact force between centralizer and pipes give rise to high friction forces that acts along the same line as the axial force in the pipes.Increased friction coefficient between centralizer and outer pipe resulted in increased discontinuity in axial force. Selection of a proper friction coefficient thus has significant influence on the results.Centralizer stiffness was evaluated by a local FE-model where a centralizer was compressed between the inner and the outer pipe. Displacement of inner pipe was evaluated as a function of applied force. The result showed that the force-displacement curve describing centralizer stiffness follows

Q (Δ)=($C{1}$ Δ) $\frac{2}{3}$

where $C{1}$     is a constant depending on dimensions and material of the centralizer. Linearized indifferent sections and with a centralizer thickness of 0,1 meter the following expression gave stiffnesses in the range 100-1000 MN/m, which agrees with stiffnesses used in the SIMLA model.displacements up to 0.3 mm the radial stiffness used in SIMLA is still good to use.

• 121. Andre, A.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures. KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures. KTH.
An experimental and numerical study of the effect of some manufacturing defects2013In: ICCM International Conferences on Composite Materials, International Committee on Composite Materials , 2013, p. 4105-4112Conference paper (Refereed)

During the manufacturing process of composite structural parts, layer of fabrics or unidirectional prepreg may have to be cut in order to fulfil production requirements. From a general mechanical point of view, cutting fibres in a composite part has a large negative impact on the mechanical properties. However, such interventions are necessary in particular cases, for example due to draping of complex geometries. A rather extensive test program was launched to investigate the effects of defects that typically could arise during manufacturing. The overall purpose of the test program was to determine knock-down factors on strength for typical manufacturing defects that occasionally arise and sometimes are hard to avoid in production: cuts/gaps and fibre angle deviations. Four types of specimens were tested, reference, intersection of cuts in adjacent layers combined with a bolt hole, cut in a zero degree ply combined with a bolt hole and specimens with misaligned fibres. The specimens with misaligned fibres were tested with three different fibre angles. In addition to the experimental procedure, FE-analyses utilising cohesive elements were conducted, and after mechanical tests, Non Destructive Investigation (NDI) and fractographic investigations were performed. An excellent correlation between analyses and experiments were obtained.

• 122.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
On Generic Road Vehicle Motion Modelling and Control2006Doctoral thesis, comprehensive summary (Other scientific)

With the increased amount of on-board electric power driven by the ongoing hybridization, new ways to realize vehicles are likely to occur. This thesis outlines a future direction of vehicle motion control based on the assumptions that: 1) future vehicle development will face an increased amount of available actuators for vehicle propulsion and control that will open up for an increased variety of possible configurations, 2) the onboard computational power will continue to increase and allow higher demands on active safety and drivability that will require a tighter interaction between sensors and actuators, 3) the trend towards more individualized vehicles on common platforms with shorter time-to-market require design approaches that allow engineering knowledge to be transferred conveniently from one generation to the next.

A methodology to facilitate the selection of vehicle configurations and the design of the corresponding vehicle motion controllers is presented. This includes a method to classify and map configurations and control strategies onto their possible influence on the vehicle's motion. Further, a structured way of implementing and managing vehicle and subsystem models that are easy to reconfigure and reuse is suggested and realised in the developed VehicleDynamics Library. In addition, generic ways to evaluate vehicle configurations, especially the use of the adhesion potential to identify safety margin and expected limit behaviour are presented.

Special attention is given to how the characteristics of a vehicle configuration can be expressed so that it can be used in vehicle motion control design. A controller structure that enables a generic approach to this is introduced and within this structure, two methods for control allocation are proposed, via tyre forces and directly. The first method uses a developed mapping of available actuators as constraints onto the achievable tyre forces and inverse tyre models to calculate the actuator inputs. The second method allocates the actuator inputs directly for an adapted problem that is linearized around the current operating point. It is shown that the methods are applicable to a variety of different vehicle configurations without redesign. Therefore, the same controller can manage a variety of vehicle configurations and there is no need to recognize and treat each different situation separately.

Finally, a road map on how to continue this research towards a possible industry implementation is given. Also suggestions on more detailed improvements for modelling and vehicle motion control are provided.

• 123.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
Global Chassis Control Based on Inverse Vehicle Dynamics Models2006In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 44, no supplement s, p. 321-328Article in journal (Refereed)

This work proposes to approach global chassis control (GCC) by means of model inversion-based feedforward with allocation directly on the actuator commands. The available degrees of freedom are used to execute the desired vehicle motion while minimizing the utilization of the tyre's grip potential. This is done by sampled constrained least-squares optimization of the linearized problem. To compensate for model errors and external disturbances, high-gain feedback is applied by means of an inverse disturbance observer. The presented method is applied in a comparison of eight vehicles with different actuator configurations for steer, drive, brake and load distribution. The approach shows a transparent and effective method to deal with the complex issue of GCC in a unitized way. It gives both a base for controller design and a structured way to compare different configurations. In practice, the transparency supports automatic on-board reconfiguration in the case of actuator hardware failure.

• 124.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
On Road Vehicle Motion Control: Striving towards synergy.2006In: Proceedings of the 8th International Symposium on Advanced Vehicle Control, 2006Conference paper (Refereed)
• 125. Andro, B.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Vibration monitoring. KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
Simplified integral energy method: Application to pass by noise2006In: Int. Congr. Sound Vib., ICSV, 2006, p. 2919-2926Conference paper (Refereed)

The pass-by noise measurements defined in a standard procedure constitute a legal test for every new vehicle. Nowadays, the improvements of the engineering process allow automotive manufacturers to reduce the vehicle development cycles. Consequently, the acoustic optimization of the vehicle applied to reduction of the exterior noise needs to be considered as soon as possible to avoid repeated road tests depending strongly on the environmental conditions. At the early stage of the development process, Renault would like therefore to use an accurate tool which predicts the engine compartment contribution to pass-by noise. This model will give indications to answer technical issues like: The influence of acoustical materials or height of the vehicle on pass-by noise in the high frequency range. In medium and high frequency domains, classical numerical methods such as the Finite Element Method (FEM) or the Boundary Element Method (BEM) are not well suited to predict the engine contribution because of the prohibitive computation time and memory occupation. Some energy methods such as statistical energy Analysis (SEA) will only give global values in each substructure and are not suited to outside airborne noise propagation. In this paper, a simplified integral energy method is developed to predict the noise induced by the engine sources during the pass-by noise test in the medium and high frequency range. We will consider a local energy balance and solve an integral equation to predict the noise emitted by the engine in a short computation time. One of the main contributions of this paper is the calculation of the visibilities between elements to take into account the presence of the engine. Standard pass-by noise measurements done on a test track are compared with those obtained by the simplified energy method.

• 126. André, Alain
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures. KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
An Experimental And Numerical Study Of The Effect Of Some Manufacturing Defects2013In: Proceedings of the 19th International conference on composite materials, ICCM-19, 2013Conference paper (Refereed)

Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.

• 127.
Volvo Car Corporation.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics. Volvo Car Corporation. Chalmers university of technology. KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics.
Optimal Steering for Double-Lane Change Entry Speed Maximization2014In: Proceedings of ACEV'14 International symposium on advanced vehicle control, 22-26 September 2014,Tokyo, Japan, Tokyo, Japan: Society of Automotive Engineers, 2014Conference paper (Refereed)

This study introduces a method for estimating the vehicle’s maximum entry speed for an ISO3888 part-2 double-lane change (DLC) test in simulation. Pseudospectral collocation in TOMLAB/ PROPT calculates the optimal steering angle that maximizes the entry speed. The rationale is to estimate the vehicle’s performance in the design phase and adapt the tuning to improve DLC ratings. A two-track vehicle dynamics model (VDM) employing non-linear tires, suspension properties and a simplified Dynamic Stability and Traction Control (DSTC) system was parameterized as a 2011 T5 FWD Volvo S60 using in-field tests and its corresponding kinematics and compliance (K&C) measurements. A sensitivity analysis on the parameters revealed certain trends that influence the entry speed, which can be varied from 69.4 up to 73.3 km/h when adapting certain vehicle features. To evaluate the method, the generated optimal steering control inputs for the simulated S60 were applied on the actual car motivating the further development of the method.

• 128.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
Development of a motion platform for the G1X radar2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis

The Giraffe 1X is a mobile short range 3D radar from Saab used for example to detect threats and create protection in a ground based air defence system. It can also be used on naval platforms for air and surface surveillance. During the development of the radar, the system needs to be tested for both sea and mobile land applications. The most convenient place for testing is on the roof of Saab’s facility in Gothenburg. There elevators can raise the radar to the roof giving an excellent view of for example Landvetter airport and the sea. To aid future verification experiments of the radar system, this project was started in order to develop and construct a motion platform used to simulate sea- and vehicle motions. During a six month period at Saab, the work of the project was started with a thorough research of motions platforms to conduct preliminary concept studies. Furthermore the concepts were drawn as 3D-CAD models in Creo Parametric in order to visualise the different solutions and present them for suppliers. The report also covers the assembly of the produced parts, together with the development of a user interface to control the motion platform.

Lastly, the result of product development is a two-degree of freedom (DOF) motion platform influenced by the gyroscopic gimbal concept. The G1X radar is mounted on a gimbal platform which is made out of two aluminium frames, whereas the outer frame rotates around an horizontal axis while the inner frame rotates around a transversely mounted horizontal axis mounted on the outer frame. Each aluminium frame is attached to a link arm which is mounted on a motor that is used to tilt the frame. The platform can be tilted _ 22 o in pitch and _ 22 o in roll. The gimbal is supported by a steel structure to allow ground clearance and to raise the radar to a comfortable working height.

• 129.
KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites.
Epoxies can solve moisture problems in nanocellulose materials2017In: International Conference on Nanotechnology for Renewable Materials 2017, TAPPI Press , 2017, p. 1220-1227Conference paper (Refereed)
• 130.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
Parametric FE-modeling of High-speed Craft Structures2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis

The primary aim of the thesis was to investigate aluminum as building material for high speed craft, study the hull structure design processes of aluminum high speed craft and develop a parametric model to reduce the modeling time during nite element analysis. An additional aim of the thesis was to study the degree of validity of the idealizations and the assumptions of the semi-empirical design methods by using the parametric model.

For the aluminum survey, a large amount of scientic papers and books related to the application of aluminum in shipbuilding industry were re-viewed while for the investigation of hull structure design, several designs of similar craft as well as all the classication rules for high speed craft were examined. The parametric model was developed on Abaqus nite ele-ment analysis software with the help of Python programming language. The study of the idealizations and the assumptions of the semi-empirical design methods was performed on a model derived by the parametric model with scanltings determined by the high speed craft classication rules of ABS.

The review on aluminum showed that only specic alloys can be applied on marine applications. It also showed that the eect of reduced mechanical properties due to welding could be decreased by introducing new welding and manufacturing techniques. The study regarding the hull structure de-sign processes indicated that high speed craft are still designed according to semi-empirical classication rules but it also showed that there is ten- dency of transiting on direct calculation methods. The developed paramet-ric model does decrease the modeling time since it is capable of modeling numerous structural arrangements. The analysis related to the idealizations and the assumptions of the semi-empirical design methods revealed that the structural hierarchy idealization and the method of dening boundary by handbook type formulas are applicable for the particular structure while the interaction eect among the structural members is only possible to be studied by detailed modeling techniques.

• 131.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
G.E.T.O.U.T. - Group Evacuation Transport at the Occurence of Unexpected Trauma"2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
• 132.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Flight Dynamics.
Aircraft Performance Monitoring on Contaminated Runways2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis

Operations on contaminated runways are a permanent challenge for the aviation community. Among the stakeholders, Airbus has decided to improve its knowledge by developing a fast post-processing software aiming at quickly identifying the runway state on operational recordings. First and foremost, the context of operations on contaminated runways is presented, with a particular emphasis on runway condition assessment methods. In a second part, the models embedded in this function are validated against simulation and more elaborated flight test analysis software. Then, the identification algorithm is validated by comparing its outputs to actual operational conditions. Finally, the robustness of the identification is assessed.

• 133. Apezetxea, I. S.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
New methodology for fast prediction of wheel wear evolution2017In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 55, no 7, p. 1071-1097Article in journal (Refereed)

In railway applications wear prediction in the wheel–rail interface is a fundamental matter in order to study problems such as wheel lifespan and the evolution of vehicle dynamic characteristic with time. However, one of the principal drawbacks of the existing methodologies for calculating the wear evolution is the computational cost. This paper proposes a new wear prediction methodology with a reduced computational cost. This methodology is based on two main steps: the first one is the substitution of the calculations over the whole network by the calculation of the contact conditions in certain characteristic point from whose result the wheel wear evolution can be inferred. The second one is the substitution of the dynamic calculation (time integration calculations) by the quasi-static calculation (the solution of the quasi-static situation of a vehicle at a certain point which is the same that neglecting the acceleration terms in the dynamic equations). These simplifications allow a significant reduction of computational cost to be obtained while maintaining an acceptable level of accuracy (error order of 5–10%). Several case studies are analysed along the paper with the objective of assessing the proposed methodology. The results obtained in the case studies allow concluding that the proposed methodology is valid for an arbitrary vehicle running through an arbitrary track layout.

• 134.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
The effect on noise emission from wind turbines due to ice accretion on rotor blades2012Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis

Swedish EPA (Naturvårdsverket) noise level guide-lines suggest that equivalent A-weighted sound pressure levels (SPL) must not exceed 40 dBA at residents. Thus, in the planning of new wind farms and their location it is crucial to estimate the disturbance it may cause to nearby residents. Wind turbine noise emission levels are guaranteed by the wind turbine manufacturer only under ice-free conditions. Thus, ice accretion on wind turbine may lead to increased wind turbine noise resulting in noise levels at nearby residents to exceed 40 dBA SPL.

The purpose of the project is to evaluate the effect on wind turbine noise emission due to ice accretion. This, by trying to quantify the ice accretion on rotor blades and correlate it to any change in noise emission. A literature study shows that the rotor blades are to be considered the primary noise source. Hence, ice accretion on rotor blades are assumed to be the main influence on noise character.

A field study is performed in two parts; as a long term measurement based on the method out-lined by IEC 61400-11 and as a short term measurement in strict accordance with IEC 61400-11. These aim to obtain noise emission levels for the case of icing conditions and ice-free conditions (reference conditions) as well as background noise levels.

An analysis is performed, which sets out to correlate ice measurements with wind turbine performance and noise emission. Data reduction procedures are performed according to IEC 61400-11.The apparent sound power levels are evaluated. This is performed for the case of icing conditions as well as for the case of ice-free onditions. A statistical evaluation of icing event is carried out.

The results show that ice accretion on wind turbine (rotor blades) may lead to drastically higher noise emission levels. The sound power levels show an average increase of 10.6 dB at 8 m/s. However, this can occur at all wind speeds from 6 m/s to 10 m/s. Higher levels of noise, (55 to 65 dBA SPL) may be caused by very small amounts of ice accretion. Occurrences of higher levels of noise, in the range of 50 to 65 dBA SPL, are not common. Noise levels exceeding 50 dBA SPL are to expected 10.3 % of the time during the winter or 3 % of the time during one year. Correlation between measured ice accumulation and noise level is weak apart from large amounts of ice. This due to statistical noise. Taking into account the noise level guide-lines of 40 dBA SPL at residents, as is recommended by Swedish EPA (Naturvårdsverket), the increased levels of windturbine noise under icing conditions may force the power production to a halt.

• 135.
Uneå University.
University of Southern Denmark. KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics.
Renewing industry cluster development via interregional industry-university links2011In: International Journal of Innovation and Regional Development, ISSN 1753-0679, Vol. 3, no 6, p. 604-631Article in journal (Refereed)

The importance of developing regional industry clusters has grown alongside the need for industries and universities to be more interlinked. A regional automotive testing industry cluster, located in the north of Sweden, is the innovative empirical setting for this research paper. Following the logic of induction, it is discovered that as the regional industry reached a certain maturity, renewal was sought via developing links to universities within other regions in Sweden. A conceptual sensemaking lens is used to theorise upon the links thus formed and to develop new insights into regional industry renewal processes and interregional industry-university links. Practical insights stemming from the case are also explained, and future research directions provided.

• 136.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
Simultaneous modal adjustment of multiple aircraft configurations using an optimization method2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis

When designing an airplane, it is necessary to know precisely the vibration modes of the structure. To do so, the Finite Element model of the airplane is adjusted to ground vibration tests results using optimization. Particularly, for airplanes able to carry several external payloads, this adjustment process must be performed for all payloads configurations. In this Master Thesis, the possibility of adjusting simultaneously different airplane configurations to their respective tests results is explored. Such a method ensures that the final Finite Element model is the same in all configurations. After implementation in the company’s software, this method is subsequently tested over two configurations. The results obtained are compared to those from separate adjustment of the models with the same variable parameters. Comparison shows that simultaneous model adjustment is promising. A better choice of variable parameters is required to improve results.

• 137.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Railway Technology.
Passive Components in Active Suspension System2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis

The concept of active technology in rail vehicles has been studied theoretically and experimentally for several decades and has now reached the stage of implementation. Active Lateral Suspension (ALS) is the active technology that leads the development in active secondary suspensions if carbody tilting is disregarded.

Active suspension systems may have an influence on running safety of the vehicle. The requirements to fulfil are related to forces between wheel and rail. The safety must be assured by the manufacturer by a safety assessment, which must be sent to the authorities before entering service. An important part of the assessment is to show that the active system, under all conditions, is part of a vehicle that runs safely on the track. The passive components in the vicinity of the active system have an important role in assuring that even a defective active system fulfils the required safety.

This master thesis aims to set requirements on the passive suspension components for the failed ALS.

The study has been conducted by varying various parameters of the vehicle with different running conditions and failure cases. The study highlights that the secondary lateral bumpstop is the most important parameter for the vehicle safety.

With soft bumpstop (low stiffness) the vehicle runs within safe limits for all studied conditions, and the effect of varying other parameters, running conditions and failure cases, is marginal. For somewhat higher stiffness (medium bumpstop), the effect of other parameters plays a critical role in ensuring safe run. For hard bumpstop, the track shift forces are above the limit values, independently of the passive component settings.

High vertical forces have been observed for certain cases with medium bumpstop, due to primary vertical bumpstop contact, which can be prevented by increasing the primary vertical damping or by increasing the vertical play. Reduction in track shift forces has been observed with the increase of primary vertical damping. The reason for the effect is not known and is proposed for further study.

• 138.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
Additive weld manufacturing and material properties effect on structural margins2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis

the FE analyses. Traditionally all parts are modeled with isotropic base material. Analyses are made on a part of the nozzle which includes both a butt weld and metal deposition and which is an interface to another part causing loads that has to be sustained by the weld and the MD. As a small part of this thesis was also a fatigue study made to a spot weld test specimen.

In order to strengthen the nozzle to prevent structural damage, an outer layer is added to the already existing metal cone by material deposition, MD, or additive manufacturing. During the manufacturing process the material will indicate some degree of anisotropic properties.

The key purpose of this thesis was to analyze how this anisotropic behaviour might affect the structural stiffener connected to this anisotropic material when exposed to a load at the end of the stiffener. Further analysis due to fatigue was also done to parts of the structure. The procedure was done by building a model and setting up the different anisotropic properties with help of a finite element program, Ansys. The material properties regarding the anisotropy of the material was changed and compared in order to see how it affected stresses and strains in the anisotropic material and it‘s surrounding materials. Further analysis was made to the properties of the weld such as the yield limit.

The result would indicate that for loadings that did not generate plastic deformations, hence elastic deformations, there were no significant difference forthe different trial values of the yield ratios. However, the differences became parent when studying large plastic deformations. Variation of the Young’s modulus would show some differences in the monitored properties for both elastic and plastic deformations. Studies of degrading the welds yield limit would show no diffrences when elastic deformations were present, but would have a big impact when large plastic deformations were present. The J-values variations for the spotweld would indicate huge differences depending on the yield limits for the spotweld and base material.

• 139.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
Hydrodynamic Investigation of WavePower Buoys2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis

With the increasing global demand for energy and environmental awareness, the interestin sustainable energy solutions has grown over the last years including wave energy.In this thesis there is a literature study on Wave Energy Converters (WEC) and a theorychapter on the power in ocean waves. The thesis work was done in in collaboration withCorPower Ocean (CPO), an innovative company developing a WEC. Two buoy shapes,both with two dierent weights were investigated and a comparison made on the eectof latching on power absorption. The work can be separated into two main parts, anumerical simulation and experimental tests.A numerical model incorporated with a mathematical description of CPO Power Take-o(PTO) physics was used to simulate and obtain numerical results on the buoy behaviourin select sea states. The benet of latching was obtained by comparing passively heavingbuoys to latch controlled buoys. The simulation model was used for various analysis ofthe system.Experiments were performed at 1:30 scale on the same buoys in a tank facility. Informationabout the hydrodynamics of the buoy, motion and power absorption was obtainedand the eect of latching on the power absorption found.Results on natural period and radiation damping were obtained and a drag coecientwas estimated.The results show that phase control by latching can substantially increase the powerabsorption of a point absorber and broaden the range of waves it can operate in. Agreementwas found in the numerical model and the experiments when investigating thebenet of latching compared to passively heaving.

• 140.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
Effect of material grade on fatigue strength and residual stresses in high strength steel welds2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis

This thesis work is concerned with effect of material grade on fatigue strength of welded joints. Fatigue strength evaluation of welded joints in as welded and post weld treated condition was carried out with effective notch method. Results of peak stress method have also been compared with those of effective notch method for as welded joints. In addition, using the results of effective notch method, the effect of important weld and global geometry factors on notch stress concentration factor has been studied with 2-level design of experiment and a mathematical relation among stress concentration factor and the geometric factors has been proposed. Overall, thickness of the base plate and toe radius is found to be the most important factors determining fatigue strength of the joint.

Welding induced residual stresses have also been predicted using 2D and 3D FEM analysis to see their effect on fatigue strength of the joints. Also, transversal residual stresses were measured using X-ray diffraction method to assess the accuracy of predicted results. Based on simulation results, effect of geometric factors on maximum value of transversal residual stress was also investigated.

• 141.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics.
Objective evaluation of vehicle handling during winter conditions2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis

Vehicle handling evaluation is a crucial part of the vehicle development process. The evaluation can be done in two ways, subjectively; by expert test drivers or objectively; by performing repeatable standard manoeuvres usually by steering robots. Subjective testing is resource intensive as prototypes need to be built. Objective testing is less so, as it can be performed in a virtual environment in conjunction with physical testing. In an e˙ort to reduce resources and time used in vehicle development, manufacturers are looking to objective testing to assess vehicle behaviour.Vehicle handling testing in winter strongly relies on subjective testing. This thesis aims to investigate into the usage of objective test strategy to assess vehicle handling behaviour in winter conditions. Manoeuvres and metrics are defined for summer con-ditions, but not for winter. Hence the goal was to define new or modified metrics and manoeuvres custom to winter testing.Data from an objective winter test was obtained and analysed. The manoeuvres used were constant radius (CR), frequency response (FR), sine with dwell (SWD) and throt-tle release in turn (TRIT). The manoeuvres were compared to public standards from the International Organization for Standards (ISO) and National Highway Traÿc Safety Administration (NHTSA) as well as the vehicle manufacturer standards.The data from a reference vehicle is compared to that from three configuration vehicles, one without anti-roll bar in the front, one without rear anti-roll bar and a standard. The di˙erence in the signals between reference and configuration vehicles is compared to the spread in data of the reference vehicle to determine the signal-to-noise ratio in the manoeuvres. The spread of reference data is analysed to determine the distribu-tion and to di˙erentiate between the two test days. To replicate vehicle behaviour in simulation, winter tyre models using brush and Magic Formula model equations were investigated. These were used in a bicycle and a VI-CarRealTime model. The perfor-mance of these are checked and compared. The bicycle model is used in an unscented Kalman filter, to investigate potential improvements in signal processing. The metrics obtained from the study of standards are checked for robustness in winter conditions by analysis of variance (ANOVA) methods. The procedure of selection of metrics from the ANOVA results is explained. Further, the manoeuvres are modified virtually in VI-CarRealTime, from the results of a sensitivity analysis. The di˙erence in metrics between reference and configuration vehicles is maximized.The final results of the thesis were; a test plan with modified manoeuvres and a set of robust metrics. Also containing important information to aid in the execution of the tests. The conclusions drawn were that the noise in winter testing is high, but the di˙erence between vehicles is statistically significant for some robust metrics. The metrics related to yaw rate were in general more robust. Open-loop throttle and steering control in manoeuvres should be avoided as far as possible. A bicycle model is not complex enough to represent vehicle behaviour at high slip angles. Performance increase of a UKF is not justified as to the e˙ort involved.

• 142.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Space Technology.
Selected Trends and Space Technologies Expected to Shape the Next Decade of SSC Services2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis

Since the early 2000s the space industry has undergone significant changes such as the advent of reusable launch vehicles and an increase of commercial opportunities. This new space age is characterized by a dynamic entrepreneurial climate, lowered barriers to access space and the emergence of new markets. New business models are being developed by many actors and the merging of space and other sectors continues, facilitating innovative and disruptive opportunities. Already established companies are adapting in various ways as efforts to stay relevant are gaining attention. The previous pace of development that was exclusively determined by governmental programs are now largely set by private and commercial ventures. Relating to all trends, new technologies and driving forces in the space industry is no trivial matter. By analyzing and examining identified trends and technologies the author has attempted to discern those that will have a significant impact on the industrial environment during the next decade. Market assessments have been summarized and interviews have been carried out. Discussions and conclusions relating to the services provided by the Swedish Space Corporation are presented. This report is intended to update the reader on the current status of the space industry, introduce concepts and provide relevant commentary on many important trends.

• 143.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
Load bearing Composite Beam in a Bus Structure2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
• 144.
Division of Structural Mechanics, Lund Institute of Technology.
Kari, LeifKTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.
Constitutive Models for Rubber IV: proceedings of the 4th European Conference for Constitutive Models for Rubber, ECCMR 2005, Stockholm, Sweden, 27-29 June 20052005Collection (editor) (Refereed)

The unique properties of elastomeric materials are taken advantage of in many engineering applications. Elastomeric units are used as couplings or mountings between stiff parts. Examples are shock absorbers, vibration insulators, flexible joints, seals and suspensions etc.

However, the complicated nature of the material behavior makes it difficult to accurately predict the performance of these units, using for example finite element modelling. It is therefore necessary that the constitutive model accurately capture relevant aspects of the mechanical behavior.

The latest development concerning constitutive modelling of rubber is collected in these proceedings. It is the fourth ECCMR-European Conference on Constitutive Modelling in a series on this subject.

Topics included in this volume are, Hyperelastic models, Strength, fracture & fatigue, Dynamic properties & the Fletcher-Gent effect, Micro-mechanical & statistical approaches, Stress softening, Viscoelasticity, Filler reinforcement, and Tyres, fiber & cord reinforced rubber.

• 145.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Aerodynamics.
Investigation of the Dynamics and Modeling of a Triangular Quadrotor Configuration2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis

In this paper the dynamics of a new type of quadrotor configuration, called Y4, is investigated. The configuration is proposed to be more energy efficient than the traditional design where four rotors are placed around the center of the aircraft frame. This by taking advantage of the benefits of a larger centered rotor in order to produce more lift. A complete mathematical model of the configuration is derived and modeled in the software Simulink. Different control laws is then developed and derived in order to control the Y4, starting with a simple PID control and then moving to non linear control methods using Lyapunov theory. The dynamics of the Y4 is then investigated by simulating different maneuvers, starting with hover and then continuing with attitude, altitude and position maneuvers. The Y4 is shown to be controllable but is less responsive than a typical quadrotor. It show more dynamics of an ordinary helicopter. The conclusion is that the Y4 might have a place in aeronautics if one prioritize power efficiency or lift power and not maneuverability, but still needs the benefits of a VTOL aircraft. However, more research regarding power optimization, design and aerodynamics needs to be done before one can say exactly how much less power the Y4 consumes compared with the standard design.

• 146. Aygul, Mustafa
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering. Khalifa University of Science Research and Technology, United Arab Emirates. KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
An investigation of distortion-induced fatigue cracking under variable amplitude loading using 3D crack propagation analysis2014In: Engineering Failure Analysis, ISSN 1350-6307, E-ISSN 1873-1961, Vol. 45, p. 151-163Article in journal (Refereed)

• 147. Aygül, M.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures. KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
Investigation of distortion-induced fatigue cracked welded details using 3D crack propagation analysis2014In: International Journal of Fatigue, ISSN 0142-1123, E-ISSN 1879-3452, Vol. 64, p. 54-66Article in journal (Refereed)

The behaviour of distortion-induced fatigue cracks in welded details in an existing bridge was studied analytically by performing crack propagation analysis based on linear elastic fracture mechanics. The real load history of the bridge was obtained from strain measurements. These loads were utilised to examine the crack growth rate and the residual service life of the cracked detail. Moreover, the effectiveness, accuracy and applicability of the crack propagation analysis on bridge structures were investigated by simulating a complex case of fatigue cracking using several crack propagation analyses. The results of the analyses revealed that the fatigue crack in the studied details had significantly different crack growth characteristics in different directions. In the thickness direction, for instance, the crack was seen to propagate at a certain rate, which increased with the propagated crack from the beginning and, as expected, the crack propagation rate decreased when the crack grew longer. The crack was subsequently arrested half way through the thickness of the plate. In the longitudinal direction, the crack was not, however, arrested in the same way as in the thickness direction and it continued to propagate at a reduced yet constant crack growth rate. The results also revealed that, even though distortion-induced fatigue cracking was usually caused by a mixed-mode condition (i.e. a combination of modes I, II and III), the governing propagation mode is still mode I. Furthermore, it was also observed that the contribution of modes II and III to crack propagation was very little and dependent on the location of the propagated crack front, as well as the geometrical configuration of the cross-beam.

• 148.
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering. KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.
Determination of dynamic and sliding friction, and observation of stick-slip phenomenon on compacted polymer powders during high-velocity compaction2006In: Polymer testing, ISSN 0142-9418, E-ISSN 1873-2348, Vol. 25, no 8, p. 1069-1080Article in journal (Refereed)

Dynamic friction, sliding friction, and the stick-slip phenomenon have been studied on compacted polymer powders during high-velocity compaction. It is particularly important from a practical point of view to distinguish the stick-slip mechanism and the sliding mechanism which occur concurrently. A practical experimental system has been successfully developed to study the dry frictional force and to measure the sliding coefficient between the polymer powder particles and the die wall during high-velocity compaction. Two new components have been introduced as relaxation assists to improve the compaction process by reducing the frictional forces. It was found that the relaxation assist device leads to an improvement in the polymer powder compaction process by giving a more homogeneous opposite velocity and a better locking of the powder bed in the compacted form with less change in dimensions. The subsequent movement of the particles can be reduced and the powder bed attains a higher density with a minimum total elastic spring-back. The relative time of the stick-slip phenomenon during the compacting stage is also reduced so that the time needed to transfer from an intermittent stick-slip state to a smooth sliding state is reduced and the powder bed slides smoothly. It was found that the dynamic, dry frictional force is intermittent (stick-slip mechanism) at low compaction rates but that at high compaction rates is becomes more smooth (sliding mechanism). Both mechanisms depend on the nature of the powder and on the compaction conditions. At the beginning of the compaction stage, the sliding coefficient decreases due to an increase in the radial to axial stress ratio until the maximum pressure has been reached. During the reorganization stage, more time is needed for large particles to move, rotate and slide due to their relatively large diameter and mass. As a result, the reorganization stage is extended and the stick-slip phenomenon is observed more with increasing particle size. Much better transfer of the pressure throughout the powder bed and less loss of pressure lead to a higher sliding coefficient due to the overall friction during the compaction process. It was found that the sliding coefficient is proportional to the density. A more homogeneous density distribution in the compacted powder and a smaller pressure loss during compaction has a major influence on the sliding coefficient and on the quality of the compacted material

• 149.
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.
Determination of springback gradient in the die on compacted polymer powders during high-velocity compaction2006In: Polymer testing, ISSN 0142-9418, E-ISSN 1873-2348, Vol. 25, no 1, p. 114-123Article in journal (Refereed)

A uniaxial high-velocity compaction process for polymer powder using a cylindrical, hardened steel die and a new technique with relaxation assist was tested with various heights. The influences of the relaxation assist device on the process characteristics are discussed. Two bonded strain gauges and a high-speed video camera system were used to investigate the springback phenomenon during the compaction process. It was found that the relaxation assist improves the compaction of the polymer powder by locking the powder bed in the compacted form. It is shown that the high-velocity compaction process is an interruption process and that the delay times between the pressure waves can be reduced by increasing the height of the relaxation assist device. The delay times between the pressure waves are also strongly dependent on the strain rate. If the height of the relaxation assist device is increased, the first gross instantaneous springback, and the total elastic springback, are reduced. In addition, the density of the powder bed is increased. The relative times of the compacting stage, decompacting stage and the reorganisation of the particles can be also controlled by altering the height of the relaxation assist.

• 150.
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.
Development of a High-Velocity Compaction process for polymer powders2005In: Polymer testing, ISSN 0142-9418, E-ISSN 1873-2348, Vol. 24, no 7, p. 909-919Article in journal (Refereed)

The High-Velocity Compaction (HVC) process for powder polymers has been studied, with a focus on the compactibility characteristics and surface morphology of the compacted materials, with and without relaxation assists, by increasing compacting quantity and direction. The basic phenomena associated with HVC are explained and the general energy principle is introduced to explain pull-out phenomena during the decompacting stage. Polyamide-11 powders with different particle size distributions have been compacted with the application of different compaction profiles, e.g. different energies and velocities. Scanning electron microscopy (SEM) and image computer board camera, (IC-PCI Imaging Technology) have been used to the study the morphological characteristics, the limit of plastic deformation and particle bonding by plastic flow at contact points, and pull-out phenomena. The relative green density is influenced more by the pre-compacting (primary compaction step) than by the post-compacting (secondary compaction step). The pressure and density distribution differences between the upper and lower surface are not uniform. Projectile supports or 'relaxation assists' are presented as a new technique to reduce pull-out phenomenon. Experimental results for different compaction profiles are presented showing the effect of varying the opposite velocity during the decompacting stage, and how to improve the homogeneous densification between the upper and lower surface and the evenness of the upper surface of the compacted powder bed by using relaxation assists.

1234567 101 - 150 of 3049
Cite
Citation style
• apa
• ieee
• modern-language-association-8th-edition
• vancouver
• Other style
More styles
Language
• de-DE
• en-GB
• en-US
• fi-FI
• nn-NO
• nn-NB
• sv-SE
• Other locale
More languages
Output format
• html
• text
• asciidoc
• rtf
v. 2.35.7
|