The Homogeneous Charge Compression Ignition (HCCI) engine is a promising engine concept that emits low concentrations of NOx and particulates and still has a high efficiency. Since the charge is auto-ignited, the auto-ignition quality of the fuel is of major importance. It has been shown in several studies that neither of the classical measures of auto-ignition quality of gasoline-like fuels, RON and MON, can alone describe this in all conditions in HCCI combustion. However, even in such cases it is possible to combine RON and MON into an octane index, OI, that describes the auto-ignition quality well in most conditions. The octane numbers are combined into the OI with the variable K according to the following equation: OI = (1-K)RON + K MON = RON – K S The OI of a sensitive fuel is the equivalent of the octane number of a primary reference fuel with the same resistance to auto-ignition in the tested condition. The K-value is dependent on the temperature and pressure history. A generic parameter Tcomp15, the temperature at 15 bar during the compression, was introduced to describe the temperature and pressure history. It was found that the K-value increases with increasing Tcomp15 and two linear equations have been suggested to describe this relationship. At high or low Tcomp15 it has been found that the sensitivity of the fuel octane quality on combustion phasing is small and the auto-ignition quality defined by the OI scale does no longer play a big role. NO affects the combustion phasing of gasoline-like fuels. This effect is most significant at low concentration where it advances the combustion phasing considerably. At higher conditions its influence is different for different fuels. A sensitive fuel is considered a good HCCI fuel since its OI changes in the same direction as the octane requirement of the engine, which would make the engine management easier. It is also likely that a sensitive fuel will enable a wider operating range. The auto-ignition quality of diesel-like fuels was studied in tests with three different strategies of mixture formation. In these tests it was found that the ignition delay increased with lower cetane number and that the cetane number described the auto-ignition quality well, even for fuels of significantly different physical properties. The experiments were, however, made at a limited range of operating conditions and low load. A good diesel-like HCCI fuel should be easy to vaporize to facilitate homogeneity. It should have a high resistance to auto-ignition, not necessarily the highest, one that allows both high and low loads at a given compression ratio. Finally, it should also function well with the injection system without a significant decrease in injection system life length. / QC 20100917

<p>Detta examensarbete har utförts av Johan Arvidsson, Marcus Leidefeldt och Tobias Unosson, studenter vid Innovations- och designingenjörsprogrammet vid Karlstads universitet. Arbetet omfattar 20 högskolepoäng varav 5 poäng är en fördjupning i ergonomi, semantik samt retorik och presentationsteknik. Projektet genomfördes under vårterminen 2006 och motsvarar 20 veckors heltidsstudier.</p><p>Uppdragsgivare för examensarbetet var HAVD AB (Hedenberg Advanced Vehicle Design) som är ett produktutvecklingsföretag inom fordonsindustrin. Handledare var Ingemar Carlson från HAVD och Lennart Wihk från Karlstads universitet. Projektet utfördes även i samarbete med Volvo Lastvagnar AB. Uppdraget som studenterna erhöll gick ut på att förbättra och utveckla in- och ursteget på en Volvolastbil av modell FH. Målet med projektet var att bygga en fungerande prototyp av lösningen på en befintlig lastbil som kunde visas upp på examensutställningen i Karlstad den 30 Maj 2006.</p><p>Studenterna fick inledningsvis en kort utbildning i projektledning som företaget anordnade i sina lokaler i Mölndal. I samband med detta fick gruppen ta del av en ny utvecklingsmetod som hade sina rötter i fordonsindustrin. Denna metod användes sedan under projektets gång som delades in i tre faser: idéfas, förstudiefas och genomförandefas. Mellan varje fas fanns en viktig punkt kallad grind då viktiga beslut fattades i samråd med företaget.</p><p>Projektet resulterade i ett mekaniskt eldrivet steg på sidan av lastbilen som transporterar chauffören upp till sin hytt på ett snabbt och säkert sätt. Lösningen döptes till ECA, Ergonomic Cabin Accesss. Slutresultatet är framtaget med fokus på förarens ergonomi och har hög realiserbarhet då det består av befintliga komponenter. Kärnan i konstruktionen är en linjärenhet som omvandlar en roterande kraft till en linjär rörelse. Konstruktionen anpassades till Volvos FH-modell genom att placeras vid dagens befintliga tre steg, vid den så kallade instegslådan. Projektgruppen arbetade fram ritningar med förslag på konstruktion och infästning för detta koncept. En lista på tänkta komponenter med en ekonomisk kalkyl togs också fram.</p><p>Slutresultatet presenterades hos HAVD i Mölndal och på Karlstad universitet i samband med examensutställningen den 30 maj 2006. Gruppen kunde dessvärre inte genomföra ett prototypbygge av ekonomiska skäl då uppdragsgivaren inte hade de resurser som krävdes. Examensarbetet ECA resulterade istället i ritningar, renderingar, animeringar och denna akademiska rapport.</p> / <p>This degree project was performed by students of the Innovation and design engineering programme on Karlstad University, Sweden. Group members have been Johan Arvidsson, Marcus Leidefeldt and Tobias Unosson. The degree project consisted of 20 weeks of work of which 5 was an individual study in literature. The project carried out during the spring of 2006.</p><p>Assigner for the project was Hedenberg Advanced Vehicle Design, HAVD, who is a development company serving the vehicle industry and specializing in interior parts and trim. Contacts were Björn Hedenberg and Ingemar Carlson, HAVD. Examiner at Karlstad University was Lennart Wihk. The project was also collaboration together with VOLVO Truck Car Corp in Gothenburg.</p><p>The task the students were given was to improve and develop a new solution for truck drivers, getting in and out of high trucks. A goal with the project was to build a functioning prototype on a VOLVO truck to be shown at the exhibit for degree projects in Karlstad, May 2006.</p><p>In this project the students participated in a project management course given by HAVD in their facilities. The group toke part of a new development method originated from the vehicle industry. This method was used as a frame for the entire project and consisted of three phases, the idea phase, research phase and the realization phase. Between each phase of the project there was a point called a gate, in which important decisions were maid in the group together with HAVD.</p><p>The project resulted in a mechanical lift, mounted onto the side of the truck transporting the driver safely up and down. The solution was named ECA, Ergonomic Cabin Access. Drawings for the concept and its mounting were completed along with an economic calculation. The final result is developed with focus on the driver ergonomics with a sensible construction using available components. The core in the construction is the so called linear motion drive. This device transforms a rotating force into a linear motion. The concept was adapted to fit a VOLVO truck by replacing the trucks previous three footsteps.</p><p>The final concept was presented at HAVD and Karlstad University at the exhibit for degree projects, 30 May 2006. The concept could not however be built into a prototype due to financial reasons. The degree project ECA resulted in drawings, renderings, animations and this academic report.</p>

The high specific bending stiffness of sandwich structures can with advantage be used in vehicles to reduce their weight and thereby potentially also their fuel consumption. However, the structure must not only meet the in-service requirements but also provide sufficient protection of the vehicle passengers in a crash situation. The in-plane compressive response of sandwich panels is investigated in this thesis, with the objective to develop a methodology capable of determining if the structural response is likely to be favourable in an energy absorption perspective. Experiments were conducted to identify possible initial failure and collapse modes. The initial failure modes of sandwich panels compressed quasi-statically in the in-plane direction were identified as global buckling, local buckling (wrinkling) and face sheet fracture. Global buckling promotes continued folding of the structure when compressed beyond failure initiation. Face sheet fracture and wrinkling can promote collapse in the form of unstable debond crack growth, stable end-crushing or ductile in-plane shear collapse. Both the unstable debond crack propagation and the stable end-crushing are related to debond crack propagation, whereas the ductile in-plane shear mode is related to microbuckling of the face sheets. The collapse behaviour of sandwich configurations initially failing due to wrinkling or face sheet fracture was investigated, using a finite element model. The model was used to determine if the panels were likely to collapse in unstable debond propagation or in a more stable end-crushing mode, promoting high energy absorption. The collapse behaviour is mainly governed by the relation between the fracture toughness of the core and the bending stiffness and strength of the face sheets. The model was successfully used to design sandwich panels for different collapse behaviour. The proposed method could therefore be used in the design process of sandwich panels subjected to in-plane compressive loads.During a crash situation the accelerations on passengers must be kept below life threatening levels. The extreme peak loads in the structure must therefore be limited. This can be achieved by different kind of triggering features.Panels with either chamfered face sheets or with grooves on the loaded edges were investigated in this thesis. The peak load was reduced with panels incorporating either of the two triggering features. Another positive effect was that the plateau load following failure initiation was increased by the triggers. This clearly illustrates that triggers can be used to promote favourable response in sandwich panels. Vehicles are harmful to the environment not only during in-serve use, but during their entire life-cycle. By use of renewable materials the impact on the environment can be reduced. The in-plane compressive response of bio-based sandwich panels was therefore investigated. Panels with hemp fibre laminates showed potential for high energy absorption and panels with a balsa wood core behaved particular well. The ductile in-plane shear collapse mode of these panels resulted in the highest energy absorption of all investigated sandwich configurations. / QC 20100728

The main goal of this work was to develop numerical models for studying the behaviour of fibres in an accelerated flow. This is of special interest for e.g. papermaking. The early stage of the paper manufacturing process determines most of the final properties of a paper sheet. The complexity of studying the flow of fibre suspensions both experimentally and numerically emphasises a need for new ideas and developments. By means of solving the evolution of a convective-dispersion equation, i.e. the Fokker-Planck equation, a fully 3D approach with respect to the position and the two fibre angles, polar and azimuthal angles, following a streamline is presented. As an input to the fibre orientation model the turbulent flow field is solved by Computational Fluid Dynamics (CFD) with second-order closure in the turbulence model. In this work two new hypotheses have been presented for the variation of the non-dimensional rotational diffusivity with non-dimensional fibre length, Lf /η and the Reynolds number based on the Taylor micro-scale of the turbulence, Reλ Parameters for the two new hy- potheses and earlier models are determined with the aim of achieving a general relation and a value of the rotational dispersion coeffcient of stiff fibres in an anisotropic turbulent fluid flow. Earlier modelling work has been focused on solving the planar approach, i.e. assuming all fibres to be in one plane. This planar approach is discussed and compared with the fully 3D approach and its validity is evaluated. The optimization of parameters for the different hypotheses correlated on a central streamline, showed a good agreement with an independent experimental result in the undisturbed region. Moreover, it is particularly interesting that the boundary layer region and the wake region are predicted fairly well and the phenomena are well described, which has not been the case earlier. It seems that the new hypothesis based on the variation of the non-dimensional fibre length, Lf /η gives the best correlation in these shear-layer regions. Further- more it was established that the planar approach fails to predict shear layers, i.e. the boundary layer and the wake regions. As emphasized in the theory section, the planar formulation is strictly valid only if all fibres are oriented in one plane, which is not the case in the shear layers. In the undisturbed region, the 3D and the planar approaches, agree in their results. This leads to the conclusion that both approaches are suitable when shear layers are not studied. / QC 20100812

This thesis deals with some aspects of crack growth in the presence of cyclic loading, i.e. fatigue. The cyclic load cases studied here are primary of non-proportional mixed mode type. Under non-proportional loading the principal stress directions rotate and, generally, the ratio between the principal stresses vary. A new criterion has been presented for prediction of incipient crack path direction after changes in load from steady Mode I to non-proportional loading. The criterion is based on FE-simulations which are used to compute the actual elasto-plastic stress state in the vicinity of the crack tip. The predictions of the criterion capture several phenomena observed in the literature, which indicates that plasticity effects have to be included in a criterion for crack path predictions under non-proportional loading. The effects of Mode II overloads on subsequent Mode I crack growth have been studied relatively little in the literature. Also, the results deviates substantially. In the present thesis, this load case has been investigated in detail, both experimentally and analytically. The results show that the Mode I crack growth rate decreases after a single Mode II load, if the R-ratio is not as high as to keep the entire Mode I load cycle above the closure level. This is based on the fact, shown in this thesis, that the reduction is caused by crack closure due to tangential displacement of crack-surface irregularities. A new loading device is presented. With this device, it is possible to apply sequential loading in Mode I and Mode II in an automated way, without having to dismount the specimens. This loading device is used to study the influence of periodic Mode II loading on Mode I crack growth. The main parameters concerning the influence of periodic Mode II loading on Mode I crack growth are; (i) the Mode I R-ratio, (ii) the Mode II magnitude and (iii) the Mode II periodicity, M (number of Mode I loads for every Mode II load). The mechanisms involved are mainly RICC (Roughness-Induced Crack Closure) and a Mode II mechanism that increases the growth rate temporary at every Mode II load. Hence, the latter becomes more significant for low M-values. The higher the Mode I R-ratio the smaller is the reduction. / QC 20101004

Detta examensarbete har utförts av Johan Arvidsson, Marcus Leidefeldt och Tobias Unosson, studenter vid Innovations- och designingenjörsprogrammet vid Karlstads universitet. Arbetet omfattar 20 högskolepoäng varav 5 poäng är en fördjupning i ergonomi, semantik samt retorik och presentationsteknik. Projektet genomfördes under vårterminen 2006 och motsvarar 20 veckors heltidsstudier. Uppdragsgivare för examensarbetet var HAVD AB (Hedenberg Advanced Vehicle Design) som är ett produktutvecklingsföretag inom fordonsindustrin. Handledare var Ingemar Carlson från HAVD och Lennart Wihk från Karlstads universitet. Projektet utfördes även i samarbete med Volvo Lastvagnar AB. Uppdraget som studenterna erhöll gick ut på att förbättra och utveckla in- och ursteget på en Volvolastbil av modell FH. Målet med projektet var att bygga en fungerande prototyp av lösningen på en befintlig lastbil som kunde visas upp på examensutställningen i Karlstad den 30 Maj 2006. Studenterna fick inledningsvis en kort utbildning i projektledning som företaget anordnade i sina lokaler i Mölndal. I samband med detta fick gruppen ta del av en ny utvecklingsmetod som hade sina rötter i fordonsindustrin. Denna metod användes sedan under projektets gång som delades in i tre faser: idéfas, förstudiefas och genomförandefas. Mellan varje fas fanns en viktig punkt kallad grind då viktiga beslut fattades i samråd med företaget. Projektet resulterade i ett mekaniskt eldrivet steg på sidan av lastbilen som transporterar chauffören upp till sin hytt på ett snabbt och säkert sätt. Lösningen döptes till ECA, Ergonomic Cabin Accesss. Slutresultatet är framtaget med fokus på förarens ergonomi och har hög realiserbarhet då det består av befintliga komponenter. Kärnan i konstruktionen är en linjärenhet som omvandlar en roterande kraft till en linjär rörelse. Konstruktionen anpassades till Volvos FH-modell genom att placeras vid dagens befintliga tre steg, vid den så kallade instegslådan. Projektgruppen arbetade fram ritningar med förslag på konstruktion och infästning för detta koncept. En lista på tänkta komponenter med en ekonomisk kalkyl togs också fram. Slutresultatet presenterades hos HAVD i Mölndal och på Karlstad universitet i samband med examensutställningen den 30 maj 2006. Gruppen kunde dessvärre inte genomföra ett prototypbygge av ekonomiska skäl då uppdragsgivaren inte hade de resurser som krävdes. Examensarbetet ECA resulterade istället i ritningar, renderingar, animeringar och denna akademiska rapport. / This degree project was performed by students of the Innovation and design engineering programme on Karlstad University, Sweden. Group members have been Johan Arvidsson, Marcus Leidefeldt and Tobias Unosson. The degree project consisted of 20 weeks of work of which 5 was an individual study in literature. The project carried out during the spring of 2006. Assigner for the project was Hedenberg Advanced Vehicle Design, HAVD, who is a development company serving the vehicle industry and specializing in interior parts and trim. Contacts were Björn Hedenberg and Ingemar Carlson, HAVD. Examiner at Karlstad University was Lennart Wihk. The project was also collaboration together with VOLVO Truck Car Corp in Gothenburg. The task the students were given was to improve and develop a new solution for truck drivers, getting in and out of high trucks. A goal with the project was to build a functioning prototype on a VOLVO truck to be shown at the exhibit for degree projects in Karlstad, May 2006. In this project the students participated in a project management course given by HAVD in their facilities. The group toke part of a new development method originated from the vehicle industry. This method was used as a frame for the entire project and consisted of three phases, the idea phase, research phase and the realization phase. Between each phase of the project there was a point called a gate, in which important decisions were maid in the group together with HAVD. The project resulted in a mechanical lift, mounted onto the side of the truck transporting the driver safely up and down. The solution was named ECA, Ergonomic Cabin Access. Drawings for the concept and its mounting were completed along with an economic calculation. The final result is developed with focus on the driver ergonomics with a sensible construction using available components. The core in the construction is the so called linear motion drive. This device transforms a rotating force into a linear motion. The concept was adapted to fit a VOLVO truck by replacing the trucks previous three footsteps. The final concept was presented at HAVD and Karlstad University at the exhibit for degree projects, 30 May 2006. The concept could not however be built into a prototype due to financial reasons. The degree project ECA resulted in drawings, renderings, animations and this academic report.

<p>The general trend toward increased use of computer models and simulations during product development has led to a need for accurate and reliable product models. The function of many products relies on contact interfaces between interacting components. To simulate the behavior of such products, accurate models of both components and interfaces are required. Depending on the purpose of the simulation, interface models of different degrees of complexity are needed. In simulation of very large systems with many interfaces, it might be computationally expensive to integrate detailed models of each individual interface. Condensed models, or abstractions, that describe the interface properties with a minimum of degrees of freedom are therefore required.</p><p>This thesis deals with mechanical interfaces with an emphasis on friction. In the four appended papers friction models are discussed in terms of condensed models, as well as in terms of more detailed contact models. The aim is to study how friction can be modeled in behavioral simulation of products and to discuss the convenience and relevance of using different types of friction models as building blocks of a system model in behavioral simulations.</p><p>Paper<b> A </b>presents a review of existing condensed friction models for sliding contacts under different running conditions and discusses the models from both simulation and tribological points of view.</p><p>In papers<b> B </b>and <b>C</b> a simplified contact model, called the elastic foundation model, is used to model friction in a boundary-lubricated rolling and sliding contact. The model is integrated in a dynamic rigid body model of a mechanical system, the system behavior is simulated, and the result is compared with experimental results.</p><p>Paper <b>D</b> discusses the application of the elastic foundation model to rough surface contact problems and investigates how the error in the elastic foundation results depends on surface roughness.</p>

<p>This licentiate thesis concerns one dimensional flow simulation of turbocharged spark ignited engines. The objective has been to contribute to the improvement of turbocharged SI engines’ performance as well as 1 D simulation capabilities.</p><p>Turbocharged engines suffer from poor gas exchange due to the high exhaust pressure created by the turbine. This results in power loss as well as high levels of residual gas, which makes the engine more prone to knock.</p><p>This thesis presents an alternative gas exchange concept, with the aim of removing the high exhaust pressure during the critical periods. This is done by splitting the two exhaust ports into two separate exhaust manifolds.</p><p>The alternative gas exchange study was performed by measurements as well as 1-D simulations. The link between measurements and simulations is very strong, and will be discussed in this thesis.</p><p>As mentioned, turbocharged engines are prone to knock. Hence, finding a method to model knock in 1-D engine simulations would improve the simulation capabilities. In this thesis a 0-D knock model, coupled to the 1-D engine model, is presented</p>

<p>The project consisted of developing an office workstation specially designed to compete at the Spanish market. The assignment was received from the Daifuku Designs, a design company in Barcelona, Spain. Daifuku Designs are well experienced in various kinds of product and interior design, but has not designed office furniture earlier. The project’s purpose was to introduce the company to the branch of office furniture.</p><p>The research phase consisted in three different parts, a survey concerning office work that was handed out to Swedish and Spanish office workers and cleaning staff, studies of the world leading companies in the branch of office furniture and educational visits at different showrooms and offices.</p><p>The project resulted in a desk that is offering a flexible space dividing system and a unique cord solution. The space dividers can be put anywhere along the desktop and are easily moved by hand. All the cords and cables are hidden in the desk and computers, phones, e.g. can be installed anywhere on the desk. The desk can be used both separately and in big office landscape. Flexibility is a common sales argument and the demand of this kind of flexibility is constantly growing. The trends to hire personnel and to work in temporary project groups are two reasons to the growing demand. The office furniture needs to be able to be used in different ways when the constellation of the project group is changing. It is a big advantage if the same desks can be used for different occasions.</p> / <p>Projektet bestod av att utveckla ett kontorsskrivbord, designat för att marknadsföras på den spanska marknaden. Uppdragsgivare var Daifuku Designs, ett designföretag i Barcelona, Spanien. Daifuku Designs har stor erfarenhet i olika sorters produkt- och inredningsdesign men har ej designat kontorsmöbler tidigare. Projektets syfte var att introducera företaget på kontorsmöbelmarknaden.</p><p>Researchfasen bestod av tre olika delar, en enkät om kontorsarbete som gavs ut till svenska och spanska kontorsarbetare samt städpersonal, studier av världsledande företag inom kontorsmöbelindustrin samt studiebesök på olika showrooms och kontor.</p><p>Projektet resulterade i ett skrivbord som erbjuder ett flexibelt avskärmningssystem samt en unik sladdlösning. Avskärmningarna kan sättas vart som helst längs skrivbordet samt kan lätt flyttas för hand. Alla sladdar och kabeldosor är gömda i skrivbordet och datorer, telefoner, etc. kan installeras vartsomhelst på skrivbordet. Skrivbordet kan användas separat så väl som i ett större kontorslandskap. Flexibilitet är ett vanligt säljargument, behovet av denna typ av flexibilitet växer hela tiden. Trenden att hyra in personal samt att jobba i projektgrupper är två anledningar till det växande behovet. Kontorsmöbeln måste kunna användas i många olika grupperingar när konstellationen i projektgruppen förändras. Det är en stor fördel om skrivbordet kan användas för många olika tillfällen.</p>

Fluid flows mainly driven by capillary forces are presented in this thesis. By means of modeling and simulations, interesting dynamics in capillary-driven flows are revealed such as coalescences, breakups, precursor films, flow instabilities, rapid spreading, rigid body motions, and reactive wetting. Diffuse-interface methods model a fluid interface as having a finite thickness endowed with physical properties such as surface tension. Two diffuse-interface models that are based on the free energy of the system are presented. The binary model, more specifically the coupled Navier-Stokes/Cahn-Hilliard equations, was used to study different two-phase flows including problems related to microfluidics. Numerical issues using this model have been addressed such as the need for mesh adaptivity and time-step restrictions. Moreover, the flexibility of this model to simulate 2D, axisymmetric, and 3D flows has been demonstrated. The factors affecting reproducibility of microdroplet depositions performed under a liquid medium are investigated. In the deposition procedure, sample solution is dispensed from the end of a capillary by the aid of a pressure pulse onto a substrate with pillar-shaped sample anchors. In both the experimental and numerical study it was shown that the deposited volume mainly depends on the capillary-substrate distance and anchor surface wettability. Furthermore, a critical equilibrium contact angle has been identified below which reproducible depositions are facilitated. The ternary model is developed for more complicated flows such as liquid phase sintering. With the introduction of a Gibbs energy functional, the governing equations are derived, consisting of convective concentration and phase-field equations which are coupled to the Navier-Stokes equations with surface tension forces. Arbitrary phase diagrams, surface energies, and typical dimensionless numbers are some input parameters into the model. Detailed analysis of the important capillary phenomena in liquid phase sintering such as reactive and nonreactive wetting and motion of two particles connected by a liquid bridge are presented. The dynamics of the wetting is found to match with a known hydrodynamic theory for spreading liquids. Factors affecting the equilibrium configuration of the particles such as equilibrium contact angles and volume ratios are also investigated. / QC 20100823