Endre søk
Begrens søket
1234567 101 - 150 of 2963
Referera
Referensformat
• apa
• 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
• 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
• Disputationsdatum (tidligste først)
• Disputationsdatum (siste først)
Merk
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
• 101.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Spårfordon.
KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Transportplanering, ekonomi och teknik. KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Spårfordon. Trafikverket. Bombardier Transportation.
Green Train: concept and technology overview2014Inngår i: International Journal of Rail Transportation, ISSN 2324-8386, Vol. 2, nr 1, s. 2-16Artikkel i tidsskrift (Fagfellevurdert)

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.

• 102.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Spårfordon.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Spårfordon.
Energy Consumption and Related Air Pollution for Scandinavian Electric Passenger Trains2006Rapport (Annet vitenskapelig)

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.

• 103.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Spårfordon. KTH, Skolan för teknikvetenskap (SCI), Centra, Järnvägsgruppen, JVG.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Spårfordon.
On the Optimization of a Track-Friendly Bogie for High Speed2009Inngår i: 21st International Symposium on Dynamics of Vehicles on Roads and Tracks, IAVSD'09, Stockholm, August 17-21, 2009., 2009Konferansepaper (Annet vitenskapelig)

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.

• 104.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Spårfordon. KTH, Skolan för teknikvetenskap (SCI), Centra, Järnvägsgruppen, JVG.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Spårfordon. KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
Radial self-steering bogies - Development, advantages and limitations2007Inngår i: ZE Vrail - Glasers Annalen: Zeitschrift fuer das gesamte System Bahn, ISSN 1618-8330, Vol. 131, nr Suppl., s. 248-259Artikkel i tidsskrift (Fagfellevurdert)

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.

• 105.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Spårfordon. KTH, Skolan för teknikvetenskap (SCI), Centra, Järnvägsgruppen, JVG.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Spårfordon.
Radial Self-Steering Bogies: Recent Developments for High Speed2009Inngår i: 7th International Conference on Railway Bogies and Running Gears / [ed] István Zobory, 2009, s. 63-72Konferansepaper (Annet vitenskapelig)

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.

• 106.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Spårfordon. KTH, Skolan för teknikvetenskap (SCI), Centra, Järnvägsgruppen, JVG.
KTH, Skolan för teknikvetenskap (SCI), Centra, Järnvägsgruppen, JVG. KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Spårfordon.
Gröna Tåget - Green Train - Train for tomorrow's travellers2011Inngår i: ZEVrail, ISSN 1618-8330, Vol. 135, s. 140-153Artikkel i tidsskrift (Annet vitenskapelig)

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.

• 107.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Spårfordon.
Models for infrastructure costs related to the wheel-rail interface2009Inngår i: Wheel-Rail Interface Handbook, Woodhead Publishing Limited, 2009, s. 608-629Kapittel i bok, del av antologi (Fagfellevurdert)

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.

• 108.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Aerodynamik.
Flödesanalys av befuktarpad: Experiment och simulering2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave

Det är känt att långa ﬂygningar förknippas med torr och obehaglig luft. Vad som dock inte är lika känt är att torr luft försämrar kroppens försvar mot bakterier och virus. Vid långa ﬂygningar kan den relativa fuktigheten sjunka till så låga nivåer som 5% och ibland lägre. Detta är ett extremt lågt värde och kan normalt bara hittas vid ökenlandskap. För att lösa detta kan ﬂygbolagen installera luftfuktare för att höja den relativa fuktigheten till mer hälsosamma nivåer. CTT Systems har en luftfuktare som är ett block bestående av sammanpressade glasﬁberark som hålls fuktigt med hjälp av vatten. När sedan varm och torr luft strömmar genom luftbefuktaren avdunstas vattnet i blocket till luften. Den fuktiga luften transporteras sedan till valda områden i ﬂygplanet. Detta projekt är gjort för att få en djupare förståelse för denna produkt. Detta arbete syftar till att erhålla en fördjupad förståelse for denna luftfuktare. Målet var att testa två olika modeller för att simulera ﬂödet genom detta glassﬁberblock. Modellerna är simulerade i SOLIDWORKS Flow Simulation vilket är en kommersiellt program för analys av ﬂödesdynamik. För att validera simuleringarna jämförs resultaten med experimentella tester. Vid jämförelsen mellan experimentella och simulerade data är tryckfallet över blocket men även hastighetsproﬁlen strax bakom blockets utlopp intressanta. Den första modellen består av en detaljrik CAD-modell av blocket. Denna modell har höga krav på mesh och resultatet blev en tidskrävande modell med låg överensstämmelse med experimentell data. I den andra modellen är luftbefuktaren modellerad som porösa block som baseras på experimentell data. Denna modell visade sig ha större potential och bättre möjligheter för att överensstämma med verkligheten.

• 109.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.
Finite Element and Dynamic Stiffness Analysis of Concrete Beam-Plate Junctions2016Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave

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.

• 110.
Chalmers, Sweden.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strukturakustik.
Boundary Element Method for Intensity Potential Approach: Predicting the Radiated Sound Power from Partially Enclosed Noise Sources2012Inngår i: Acta Acoustica united with Acustica, ISSN 1610-1928, E-ISSN 1861-9959, Vol. 98, nr 4, s. 588-599Artikkel i tidsskrift (Fagfellevurdert)

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.

• 111.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
Concept study for cost and weight reduction of a barge container sized module2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave

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%.

• 112.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Marina system.
Naval ArchitectureRICKY ANDERSSONrickya@kth.se0739-5332522015-06-2015Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave

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.

• 113.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
Utvärdering av infästningar i sandwichkonstruktioner för fordonsapplikationer2011Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave

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.

• 114.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
Pipe-In-Pipe system for offshore applications: Post buckling analysis associated with thermal expansion2014Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave

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.

• 115. Andre, A.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner. KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner. KTH.
An experimental and numerical study of the effect of some manufacturing defects2013Inngår i: ICCM International Conferences on Composite Materials, International Committee on Composite Materials , 2013, s. 4105-4112Konferansepaper (Fagfellevurdert)

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.

• 116.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
On Generic Road Vehicle Motion Modelling and Control2006Doktoravhandling, med artikler (Annet vitenskapelig)

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.

• 117.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
Global Chassis Control Based on Inverse Vehicle Dynamics Models2006Inngår i: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 44, nr supplement s, s. 321-328Artikkel i tidsskrift (Fagfellevurdert)

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.

• 118.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
On Road Vehicle Motion Control: Striving towards synergy.2006Inngår i: Proceedings of the 8th International Symposium on Advanced Vehicle Control, 2006Konferansepaper (Fagfellevurdert)
• 119. Andro, B.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Vibrationsövervakning. KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.
Simplified integral energy method: Application to pass by noise2006Inngår i: Int. Congr. Sound Vib., ICSV, 2006, s. 2919-2926Konferansepaper (Fagfellevurdert)

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.

• 120. André, Alain
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner. KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
An Experimental And Numerical Study Of The Effect Of Some Manufacturing Defects2013Inngår i: Proceedings of the 19th International conference on composite materials, ICCM-19, 2013Konferansepaper (Fagfellevurdert)

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.

• 121.
Volvo Car Corporation.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik. Volvo Car Corporation. Chalmers university of technology. KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
Optimal Steering for Double-Lane Change Entry Speed Maximization2014Inngår i: Proceedings of ACEV'14 International symposium on advanced vehicle control, 22-26 September 2014,Tokyo, Japan, Tokyo, Japan: Society of Automotive Engineers, 2014Konferansepaper (Fagfellevurdert)

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.

• 122.
KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Biokompositer.
Epoxies can solve moisture problems in nanocellulose materials2017Inngår i: International Conference on Nanotechnology for Renewable Materials 2017, TAPPI Press , 2017, s. 1220-1227Konferansepaper (Fagfellevurdert)
• 123.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Marina system.
Parametric FE-modeling of High-speed Craft Structures2012Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave

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.

• 124.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
G.E.T.O.U.T. - Group Evacuation Transport at the Occurence of Unexpected Trauma"2012Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
• 125.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Flygdynamik.
Aircraft Performance Monitoring on Contaminated Runways2012Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave

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.

• 126. Apezetxea, I. S.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
New methodology for fast prediction of wheel wear evolution2017Inngår i: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 55, nr 7, s. 1071-1097Artikkel i tidsskrift (Fagfellevurdert)

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.

• 127.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.
The effect on noise emission from wind turbines due to ice accretion on rotor blades2012Independent thesis Advanced level (degree of Master (One Year)), 20 poäng / 30 hpOppgave

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.

• 128.
Uneå University.
University of Southern Denmark. KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
Renewing industry cluster development via interregional industry-university links2011Inngår i: International Journal of Innovation and Regional Development, ISSN 1753-0679, Vol. 3, nr 6, s. 604-631Artikkel i tidsskrift (Fagfellevurdert)

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.

• 129.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
Simultaneous modal adjustment of multiple aircraft configurations using an optimization method2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave

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.

• 130.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Järnvägsteknik.
Passive Components in Active Suspension System2013Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave

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.

• 131.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
Additive weld manufacturing and material properties effect on structural margins2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave

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.

• 132.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Marina system.
Hydrodynamic Investigation of WavePower Buoys2013Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave

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.

• 133.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
Effect of material grade on fatigue strength and residual stresses in high strength steel welds2012Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave

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.

• 134.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Fordonsdynamik.
Objective evaluation of vehicle handling during winter conditions2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave

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.

• 135.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
Load bearing Composite Beam in a Bus Structure2012Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
• 136.
Division of Structural Mechanics, Lund Institute of Technology.
Kari, LeifKTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strukturakustik.
Constitutive Models for Rubber IV: proceedings of the 4th European Conference for Constitutive Models for Rubber, ECCMR 2005, Stockholm, Sweden, 27-29 June 20052005Collection/Antologi (Fagfellevurdert)

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.

• 137.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Aerodynamik.
Investigation of the Dynamics and Modeling of a Triangular Quadrotor Configuration2014Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave

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.

• 138. Aygul, Mustafa
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg. Khalifa University of Science Research and Technology, United Arab Emirates. KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Bro- och stålbyggnad.
An investigation of distortion-induced fatigue cracking under variable amplitude loading using 3D crack propagation analysis2014Inngår i: Engineering Failure Analysis, ISSN 1350-6307, E-ISSN 1873-1961, Vol. 45, s. 151-163Artikkel i tidsskrift (Fagfellevurdert)

• 139. Aygül, M.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner. KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Bro- och stålbyggnad.
Investigation of distortion-induced fatigue cracked welded details using 3D crack propagation analysis2014Inngår i: International Journal of Fatigue, ISSN 0142-1123, E-ISSN 1879-3452, Vol. 64, s. 54-66Artikkel i tidsskrift (Fagfellevurdert)

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.

• 140.
KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg. KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strukturakustik.
Determination of dynamic and sliding friction, and observation of stick-slip phenomenon on compacted polymer powders during high-velocity compaction2006Inngår i: Polymer testing, ISSN 0142-9418, E-ISSN 1873-2348, Vol. 25, nr 8, s. 1069-1080Artikkel i tidsskrift (Fagfellevurdert)

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

• 141.
KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strukturakustik.
Determination of springback gradient in the die on compacted polymer powders during high-velocity compaction2006Inngår i: Polymer testing, ISSN 0142-9418, E-ISSN 1873-2348, Vol. 25, nr 1, s. 114-123Artikkel i tidsskrift (Fagfellevurdert)

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.

• 142.
KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strukturakustik.
Development of a High-Velocity Compaction process for polymer powders2005Inngår i: Polymer testing, ISSN 0142-9418, E-ISSN 1873-2348, Vol. 24, nr 7, s. 909-919Artikkel i tidsskrift (Fagfellevurdert)

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.

• 143.
KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strukturakustik.
Polymer-nanofiller prepared by high-energy ball milling and high velocity cold compaction2008Inngår i: Polymer Composites, ISSN 0272-8397, E-ISSN 1548-0569, Vol. 29, nr 3, s. 252-261Artikkel i tidsskrift (Fagfellevurdert)

High-energy ball milling using comilling in a solid state by low-temperature mechanical alloying to prepare nickel-ferrite (NiFe2O4) nanopowders and ultrafine poly(methyl methacrylate) (PMMA), dispersing nanoparticles in a polymer matrix, and a uniaxial high-velocity cold compaction process using a cylindrical, hardened steel die and a new technique with relaxation assists have been studied. The focus has been on the particle size distributions of the nanocomposite powder during the milling and on the surface morphology of the nanocomposite-compacted materials after compaction with and without relaxation assists. Experimental results for different milling systems are presented showing the effects of milling time and material ratio. It was found that a longer mixing time give a higher degree of dispersion of the nanopowder on the PMMA particle surfaces. Furthermore, with increasing content of NiFe2O4 nanopowder, the reduction of the particle size was more effective. Different postcompacting profiles, i.e. different energy distributions between the upper and lower parts of the compacted powder bed, lead to different movements of the various particles and particle layers. Uniformity, homogeneity, and densification on the surfaces in the compacted powder are influenced by the postcompacting magnitude and direction. It was found that the relaxation assist device leads to an improvement in the polymer powder compaction process by reducing the expansion of the compacted volume and by reducing the different opposite velocities, giving the compacted composite bed a more homogeneous opposite velocity during the decompacting stage and reducing the delay time between the successive pressure waves.

• 144.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
High performance nanocomposite polymer electrolytes2006Inngår i: Composite interfaces (Print), ISSN 0927-6440, E-ISSN 1568-5543, Vol. 13, nr 4-6, s. 545-559Artikkel i tidsskrift (Fagfellevurdert)

Solid lithium-conducting nanocomposite polymer electrolytes based on poly(oxyethylene) (POE) were prepared using high aspect ratio cellulosic whiskers and lithium imide salt, LiTFSI. The cellulosic whiskers were extracted from tunicate - a sea animal - and consisted of slender parallelepiped rods that have an average length around 1 μm and a width close to 15 nm. High performance nanocomposite electrolytes were obtained. The filler provided a high reinforcing effect, despite the favorable cellulose/POE interactions that were expected to decrease the possibility of interwhisker connection and formation of a percolating cellulosic network, while a high level of ionic conductivity was retained with respect to unfilled polymer electrolytes. Cross-linking and plasticizing of the matrix as well as preparation of the composites from an organic medium were also investigated.

• 145.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner. Université Joseph Fourier, France.
Review of recent research into cellulosic whiskers, their properties and their application in nanocomposite field2005Inngår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 6, nr 2, s. 612-626Artikkel i tidsskrift (Fagfellevurdert)

There are numerous examples where animals or plants synthesize extracellular high-performance skeletal biocomposites consisting of a matrix reinforced by fibrous biopolymers. Cellulose, the world's most abundant natural, renewable, biodegradable polymer, is a classical example of these reinforcing elements, which occur as whiskerlike microfibrils that are biosynthesized and deposited in a continuous fashion. In many cases, this mode of biogenesis leads to crystalline microfibrils that are almost defect-free, with the consequence of axial physical properties approaching those of perfect crystals. This quite "primitive" polymer can be used to create high performance nanocomposites presenting outstanding properties. This reinforcing capability results from the intrinsic chemical nature of cellulose and from its hierarchical structure. Aqueous suspensions of cellulose crystallites can be prepared by acid hydrolysis of cellulose. The object of this treatment is to dissolve away regions of low lateral order so that the water-insoluble, highly crystalline residue may be converted into a stable suspension by subsequent vigorous mechanical shearing action. During the past decade, many works have been devoted to mimic biocomposites by blending cellulose whiskers from different sources with polymer matrixes.

• 146.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
Optimeringsmetoder för ASMC-strukturer2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave

Thin metal sheets have for long been the dominant structural components in automotive bodies, but as environmental concerns mount new materials are needed to reduce mass. Advanced Sheet Moulding Compounds (ASMC) is a carbon fibre composite with short fibres and has been put forward as an alternative. It is both light and has good durability and can be formed in a mould similarly to steel sheets. A distinct advantage is that unlike for steel sheets the thickness in an ASMC component can be varied and stiffeners integrated. This creates great opportunities for optimisation, but as know-how in the industry is scarce a methodology is necessary. This master’s thesis describes a method developed for optimising structural components manufactured in ASMC by analysing a backplate mounted in a Body-In-White (BIW). The optimisation design process was first developed in a simplified model made to mimic a BIW without all the complexities therein. In this thesis free-size optimisation was done individually and coupled with adding uni-directional (UD) fibres and ribs to the backplate. This process was then verified in an accurate car body model and the process translated rather well to a more realistic model as favourable results were obtained. Optimisation resulted in more than 50% decrease in the component’s mass and body torsional stiffness could be increased by up to 7%. A step-by-step guide for this process is presented. Moving forward the design methodology needs to be verified and developed further for different structures and load cases. It is believed that the process detailed works well for many different structures as is, but improvements can be made and are ultimately necessary.

• 147.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
Estimation of the material parameters of a sandwich beam from measured eigenfrequenciesManuskript (Annet vitenskapelig)
• 148.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
Vibration of sandwich beams2006Doktoravhandling, med artikler (Annet vitenskapelig)

Some aspects and properties of the lateral vibration of sandwich beams are investigated, including the concept of apparent bending stiffness and shear modulus, allowing the sandwich beam dynamics to be approximately described by classical beam theory. A sixth order beam model is derived including boundary conditions, and the free and forced response of some beam configurations analyzed. The possibility of computing material parameters from measured eigenfrequencies, i. e. inverse analysis, is considered. The higher order model is also utilized for investigation of the energy propagation through sandwich composite beams and the transmission over different junctions.

• 149.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
Vibration transmission through sandwich composite beam junctionsManuskript (Annet vitenskapelig)
• 150.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
Flexural vibrations of a three-layer sandwich beam - Using ordinary fourth order beam theory in combination with frequency dependent parameters to predict the flexural dynamics of a sandwich beam2005Inngår i: Sandwich Structures7: Advancing with Sandwich Structures and Materials / [ed] Thomsen, OT; Bozhevolnaya, E; Lyckegaard, A, 2005, s. 567-575Konferansepaper (Fagfellevurdert)

The purpose of this work has been to evaluate the possibility of using modified lower order methods - such as the Bernoulli-Euler or Timoshenko beam theories with frequency dependent parameters - to calculate the response of sandwich beams subject to different end conditions. The models have been verified by measurements on a freely suspended asymmetric sandwich beam with aluminium laminates and a plastic foam core, indicating good agreement.

1234567 101 - 150 of 2963
Referera
Referensformat
• apa
• 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
v. 2.35.7
| |