Syftet med examensarbetet var att undersöka manganhaltens inverkan på skärbarheten och de mekaniska egenskaperna i varmarbetsstål Dievar samt kontrollera och undersöka hypotesen att material med låga Ac1 temperaturer maskinbearbetas svårare än material med högre temperaturer.  Skärbarhet hos Dievar med olika Mn-halt från 0,084 till 1,59 vikts% studerades i härdat tillstånd med ett pinnfräsningstest. Skärbarheten karakteriserades genom mätning av verktygslivslängd och skärkrafter. Verktygslivslängd bestämdes av fasförslitningsutvecklingen på verktyget. Förslitningsmekanismer studerades på verktygets spån- och släppningssidor med hjälp av svepelektronmikroskop (SEM). Dragprov vid rums- och förhöjd temperatur genomfördes för att studera mangans inverkan på hållfasthetsegenskaper hos Dievar. Mikrostrukturen av stålen i härdat och anlöpt tillstånd undersöktes i SEM. Ac1 temperatur i stålen uppmättes med dilatometer. Mangan visade sig ha en positiv inverkan på skärbarheten i Dievar. Verktygets livslängd var två gånger längre vid pinnfräsning av Dievar 1,59 vikts% Mn i jämförelse med Dievar 0,084 och 0,27 vikts% Mn. Mer påkletningsbenägna stål med lägre Mn-halt orsakade mer adhesiv nötning och urflisning av fräsens skäregg. Detta ledde till att förslitningen utvecklades hastigare under bearbetningen av Dievar med lägre Mn-halt. De uppmätta skärkrafterna under bearbetning förklarade inte skillnaden i skärbarheten mellan Dievar med olika Mn-halt; skärkrafter var lika i alla material. Dievar med högre Mn-halt innehöll mindre primära molybdenrika karbider än Dievar med lägre Mn-halt. Detta berodde på att manganet minskade Ac1 temperaturen i Dievar. Mn-halten i Dievar påverkade inte hållfasthetsegenskaperna vid rumstemperatur men visade en tendens att minska stålets hållfasthet vid hög temperatur. De genomförda undersökningarna bekräftade inte hypotesen att material med lägre Ac1 temperaturer har sämre maskinbearbetbarhet än material med högre temperaturer. Dievar 1,59 vikts% Mn hade betydligt lägre Ac1 temperatur än andra Dievar-material samt modifierat Orvar men visade sig vara lättare att bearbeta. / The aim of the study was to investigate influence of manganese content on the machinability and mechanical properties of a hot-work tool steel Dievar and verify a hypothesis that materials with low Ac1 temperatures are more difficult to machine than steels with higher Ac1 temperatures. Machinability of Dievar with varying manganese content from 0,084 to 1,59 wt% was investigated in the hardened condition in the milling operation. The machinability of the steels was characterized by measuring tool life and cutting forces during machining. The tool life was estimated by measuring flank wear on the tools. Wear mechanisms were investigated on the clearance and rake faces of the tools by SEM. Tensile tests at room and elevated temperatures were carried out to examine the manganese influence on the mechanical properties of Dievar. Microstructure of the steels in hardened and tempered condition was investigated by SEM. Dilatometer tests were done to determine the Ac1 temperature for the steels. Manganese content showed to have a positive effect on the machinability of Dievar. Two times longer tool life was reached when end milling Dievar 1,59 wt% Mn comparing to end milling Dievar 0,084 and 0,27 wt% Mn. More adhesive wear and chipping were observed on the tools after end milling the lower manganese containing steels. This resulted in more progressive wear and shorter tool life during machining of these steels. The measured cutting forces could not be related to the difference in machinability of the steels with different manganese content. The generated cutting forces were similar for all the tested steels. Dievar with higher manganese content contained less primary molybdenum-rich carbides in the microstructure. It was related to the lower Ac1 temperature of Dievar 1,59 wt% Mn comparing to the lower manganese containing steels. The manganese content showed no influence on the tensile properties of Dievar at room temperature and a tendency to a slight decrease in yield and ultimate strength at the elevated temperature. The machinability tests carried out in the present study did not confirm the hypothesis that materials with low Ac1 temperatures have poor machinability.  Dievar 1,59 wt% Mn had much lower Ac1 temperatures than the other Dievar steels and the modified Orvar steel but showed to have an improved machinability compared to the others.

Målet med detta examensarbete har varit att presentera ett relevant beslutsunderlag för val av grundstoppningsmaterial till sittmöbler i dagligt bruk.Genom test av hållbarhet och förslitning hos fem olika sitsar med olika stoppningsmaterial och genom blindtester av dessa fem sitsar, före och efter hållbarhets- och förslitningstest, har jämförbara värden, både objektiva och subjektiva upplevelser tagit fram.Det ur alla synvinklar bästa alternativet både med hänsyn till pris, hållbarhet och subjektiv upplevelse av komfort och hållbarhet visades sig vara vulkaniserat tagel.

Summary I have a great interest in bouzoukis and since I, during my education in guitar making, mainly have focused on building bouzoukis and other traditional folk instruments, I have chosen the bouzouki as the object of my degree project. In connection to the making of these instruments, I started to consider the construction of the bouzouki and why the bouzouki has such a characteristic sound. One of my theories is based on the fact that most bouzoukis are made with floating bridges instead of glued pinbridges. Do these types of bridges differ from each other tonally and if so, how much and in what way? To receive answers to my questions, I have built two identical bouzoukis with different types of bridges, one with a glued pinbridge and one with a floating bridge. I have been very precise in the making of these instruments, giving them the exact same dimensions and using material from the same piece of wood. This to make sure that the instruments should be as exactly alike as possible. After finishing the making of the bouzoukis, I arranged for a sound test where I let musicians play and listen to the instruments. After doing this I let the same musicians fill in a form with questions regarding each instruments tonal characteristics and it’s fields of application. By compiling the answers from the sound test, I have come to a conclusion regarding what tonally separates a bouzouki with a glued pinbridge from a bouzouki with a floating bridge. In addition to this I have found out what other instrument makers considers to be the difference between these two types of bridges. Beside the project described above I also present a brief history of the bouzouki. / Sammanfattning Jag har valt att göra ett examensarbete som grundar sig på mitt stora intresse för bouzoukis. Jag har under min utbildning i gitarrbyggeri främst riktat in mig på att bygga bouzoukis samt liknande folkinstrument. I samband med dessa byggen så har jag fundera mycket över instrumentets konstruktion och vad det är som gör att bouzoukin har ett så karakteristiskt ljud. En av mina funderingar består i varför de flesta bouzoukis är utrustade med ett tryckande stall istället för ett limmat stall. Skiljer sig dessa stalltyper från varandra tonalt och i sådant fall hur mycket och på vilket sätt? För att få svar på mina frågor har jag byggt två stycken bouzoukis som är identiskt lika bortsett från stalltypen. Den ena har ett limmat stall och den andra ett tryckande stall. Jag har varit mycket noggrann med att tillverka bouzoukierna med exakt samma dimensioner och med material som kommer från samma trästock. Detta för att försäkra mig om att instrumenten ska bli så lika som det bara går. Därefter har jag anordnat ett ”lyssningstest” där jag har låtit musiker spela och lyssna på instrumenten. Musikerna har sedan fått fylla i ett formulär innehållande frågor om instrumentens tonala egenskaper samt om deras användningsområden. Genom att sammanställa svaren från lyssningstestet har jag kommit fram till en slutsats om vad det är som tonalt skiljer ett limmat från ett tryckande stall hos en bouzouki. Jag har även att tagit reda på vad andra instrumentbyggare anser att det är för skillnader mellan de olika stalltyperna, samt hur bouzoukins historia i stora drag ser ut.

To study engineering can be difficult, especially transforming theoretical knowledge into practice. To address this issue, Otto and Wood have developed a reverse engineering and redesign methodology, suggesting that it can be used as a tool in the process of learning mechanical engineering and design. The aim with this report is to evaluate this statement, emphasizing on the reverse engineering process and evaluating its usefulness as an educational tool. In order to fully understand the process, two cordless screwdrivers will be reverse engineered, functioning as an example throughout the report. A theoretical background of the process will be introduced, including descriptions concerning the different steps and their encompassed tools, tests and methods. Trough the implementation, the screwdrivers are disassembled, analysed and experienced, resulting in a clear product specification with information of components and product functions. One example is the assembly plan, were the product structure is presented as two subassemblies with “layer on layer” assembly. Another result of the implementation is that the reverse engineering process was experienced in reality, exposing the required modifications necessary in order to function as an educational tool. The main issue for the process is its focus on customer needs instead of product focus. Therefore, it is suggested that a new reverse engineering process based on the existing one should be developed, focusing more on the product and less on the customer to better suit an educational purpose.

<p>To study engineering can be difficult, especially transforming theoretical knowledge into practice. To address this issue, Otto and Wood have developed a reverse engineering and redesign methodology, suggesting that it can be used as a tool in the process of learning mechanical engineering and design. The aim with this report is to</p><p>evaluate this statement, emphasizing on the reverse engineering process and evaluating its usefulness as an educational tool. In order to fully understand the process, two cordless screwdrivers will be reverse engineered, functioning as an example throughout the report. A theoretical background of the process will be</p><p>introduced, including descriptions concerning the different steps and their encompassed tools, tests and methods. Trough the implementation, the screwdrivers are disassembled, analysed and experienced, resulting in a clear product specification</p><p>with information of components and product functions. One example is the assembly plan, were the product structure is presented as two subassemblies with “layer on layer” assembly. Another result of the implementation is that the reverse engineering</p><p>process was experienced in reality, exposing the required modifications necessary in order to function as an educational tool. The main issue for the process is its focus on customer needs instead of product focus. Therefore, it is suggested that a new reverse</p><p>engineering process based on the existing one should be developed, focusing more on the product and less on the customer to better suit an educational purpose.</p>

<p>In this paper the possibilities to replace metal with plastic in products for the building industry were looked into. The first part was a market examination where several suitable products were found. After evaluation the door latch for in-house doors was selected to be re-designed to better suit the properties of plastic.</p><p>New types of mechanisms were designed with different functions that use the benefits of plastic materials. Models of these mechanisms were developed to evaluate their function. The components in the different mechanisms were adapted for manufacturing with injection moulding.</p><p>To confirm that the plastic material could handle the appearing stresses calculations on the most vulnerable parts were carried out. The result of the re-design process was three types of door latches that all fit in the doors standard cut-out. Model Classic is similar to the existing mechanism but the number of components is less than half and assembly and manufacturing is simplified. Model Magneto uses a magnet to move the locking part when the door is closed. Opening and locking is the same as Classic. Model Push/Pull uses a pushing or pulling motion to open the door depending on which side it is operated from.</p> / <p>I arbetet undersöktes ersättning av metallprodukter med plast inom byggindustrin. Första delen är en enkel marknadsundersökning där produkter som kan vara lämpliga och lönsamma att ersätta söks. Marknadsundersökningen ledde till att flera lämpliga produkter hittades och efter sållning valdes dörrmekanismen till innedörrar för vidareutveckling.</p><p>I den andra delen som kallas Re-design har dörrmekanismen omkonstruerats och en ny funktion har utvecklats för att passa för tillverkning i plast och för att kunna dra nytta av de fördelar som plastmaterialet erbjuder. Efter idégenerering och sållning har modeller byggts för att testa funktioner. Därefter anpassades de utvalda mekanismerna för tillverkning med formsprutning.</p><p>Beräkningar av mekanismens mest belastade delar utfördes i beräkningsprogrammet Abaqus. Arbetet resulterade i tre varianter av innerdörrsmekanismen som alla passar i dörrens standarduttag, dessa fick namnen Classic, Magneto och Push/pull. Classic har samma funktion som den existerande varianten men antalet delar är mindre än hälften och monteringen och tillverkning är enklare. Magneto liknar i stor utsträckning Classic men vid öppen dörr ligger kolven jämns med dörren och dras in i låsblecket av en magnet istället för av en fjäder som i Classic. Push/pull har en annorlunda öppningsfunktion där drag/tryck används för att öppna dörren istället för en vridrörelse.</p>

<p>Magnetorheological (MR) rubber materials are the solid analogue of magnetorheological fluids; i.e. their rheological properties can be controlled continously, rapidly, and reversibly by an applied magnetic field. They consist of magnetically polarisable particles in an elastomer matrix and they can be made to respond to changes in their environment; hence, they are considered as "smart" materials. Examples of potential applications for these materials are adaptive tuned vibration absorbers, stiffness-tuneable mounts and suspensions, and automotive bushings.</p><p>The purpose of this work was to increase the knowledge relating to magnetorheological materials for damping applications. The materials should exhibit a large response to an applied magnetic field, and have good mechanical and long-term properties.</p><p>MR rubber materials were made from nitrile, natural and silicone rubber, with irregularly shaped iron particles several micrometres in size. The particles were not aligned by a magnetic field prior to the vulcanisation; hence, the materials can be considered to be isotropic. These materials show a large MR effect, i.e. an increase in the shear modulus when a magnetic field is applied, although the particles are not aligned within the material. This is explained by the low critical particle volume concentration (CPVC) of such particles. Similar behaviour can be obtained with materials containing carbonyl iron, if the particles are aggregated so that they behave like large irregular particles. The iron particle concentration must be very close to the CPVC in order to obtain a large MR effect without alignment of the particles.</p><p>The absolute MR effect (MPa) in an isotropic MR rubber material with large irregular iron particles is independent of the matrix material, and the relative MR effect (%) can thus be increased by the addition of plasticisers. However, the obtainable effect is limited by the reinforcement of the particles and by friction between the particles. Therefore, it is very difficult, if not impossible, to achieve an MR effect larger than 60%.</p><p>Other ways of increasing the MR effect are to increase the strength of the magnetic field, although the materials saturate magnetically at high field strengths, or to use small strain amplitudes. The strong strain amplitude dependence of the MR effect suggests that MR rubber materials are most suitable for low amplitude applications, such as sound and vibration insulation. Measurements at frequencies within the audible frequency range show that this is a promising application for MR rubber materials.</p><p>The incorporation of large amounts of iron into the rubber matrix decreases the oxidative stability dramatically. This is probably due to iron oxides on the surface of the particles, and to the fact that the oxidation rate is enhanced by iron ions, which are able to diffuse into the matrix. Standard antioxidants do not provide sufficient stabilisation for MR rubbers. Thus, proper stabilisation systems have to be found in order for these materials to be successful in applications.</p>

<p>Transverse anisotropy is an important phenomenon of practical and scientific interest. Although the presence of ray tissue explains the high radial modulus in many hardwoods, experimental data in the literature shows that this is not the case for pine. It is possible that anisotropy in softwoods may be explained by the cellular structure and associated deformation mechanisms.</p><p>An experimental approach was developed by which local radial modulus in spruce was determined at sub-annual ring scale. Digital speckle photography (DSP) was used, and the density distribution was carefully characterized using x-ray densitometry and the SilviScan apparatus. A unique set of data was generated for radial modulus versus a wide range of densities. This was possible since earlywood density shows large density variations in spruce. Qualitative comparison was made between data and predictions from stretching and bending honeycomb models. The hypothesis for presence of cell wall stretching was supported by data.</p><p>A model for wood was therefore developed where both cell wall bending and stretching are included. The purpose was a model for predictions of softwood moduli over a wide range of densities. The relative importance of the deformation mechanisms was investigated in a parametric study. A two-phase model was developed and radial and tangential moduli were predicted. Comparison with experimental data showed good agreement considering the nature of the model (density is the only input parameter). Agreement is much better than for a regular honeycomb model. According to the model, cell wall bending dominates at both low and high densities during tangential loading. In radial loading, cell wall stretching dominates at higher densities.</p>

<p>Atmospheric corrosion, the most common form of metal corrosion, occurs within the interfacial region between a solid, and the surrounding atmosphere. In fact three phases and two interfaces are involved: the gas, a thin liquid layer, a solid, the gas/liquid and the liquid/solid interfaces. In this thesis, the vapor/liquid and liquid/metal interfaces have been studied by the in-situ techniques vibrational sum frequency spectroscopy (VSFS), and infrared reflection/absorption spectroscopy (IRAS). The main focus has been on characterization of the corrosive organic molecules formic acid, acetic acid, and acetaldehyde, at the two interfaces. Additionally, the headgroup of sodium dodecyl sulfate (SDS) has been examined at the air/water interface.</p><p>VSFS is an inherently surface sensitive laser spectroscopy technique, which provides vibrational spectra solely of the molecules residing at the surface of for example a liquid, despite the vast excess of the same molecules in the bulk. To obtain a comprehensive molecular picture of the organic compounds at the air/liquid interface, studies have been undertaken in several spectral regions, targeting the CH, C=O, C-O, OH, and SO3 stretching vibrations. Furthermore, the surrounding water molecules have been investigated in order to study hydration phenomena. Acetaldehyde has been determined to partly form a gem-diol (CH3CH(OH)2) at the air/water interface, whereas acetic acid forms various hydrogen-bonded species, with hydrated monomers at low concentrations and centrosymmetric cyclic dimers at high concentrations. Formic acid was found to form a different complex at very high concentrations, in addition to the species observed at low concentrations. Performing experiments with different polarizations of the laser beams has enabled the determination of the orientation of the interfacial molecules. The methyl group of acetic acid was concluded to be oriented close to the surface normal throughout the concentration range, whereas the tilt angle of the CH group of formic acid was determined to be ~35°. The SDS studies revealed that the headgroup orientation is constant in a wide range of concentrations, and also in the presence of sodium chloride.</p><p>IRAS has provided information regarding the composition and kinetics of the corrosion products formed upon exposure of a zinc oxide surface to the organic compounds. The importance of the water adlayer on metal surfaces has been confirmed by the faster kinetics observed at higher relative humidities. Exposure to formic acid resulted in the formation of zinc formate, whereas both acetic acid and acetaldehyde formed zinc acetate upon reaction with the zinc oxide surface. However, the kinetics were faster for acetic acid than acetaldehyde, which was explained in terms of an acetate-induced zinc dissolution process and a more complicated reaction path involved in the acetaldehyde case to form the zinc acetate surface species. Scanning electron microscopy indicated the formation of radially growing reaction products for acetic acid and filiform corrosion for acetaldehyde.</p>

<p>This Thesis presents two different deposition techniques for the synthesis of Ti₂AlC coatings. First, I have fabricated Ti₂AlC coatings by high velocity oxy-fuel (HVOF) spraying. Analysis with scanning electron microscopy (SEM) show dense coatings with thicknesses of ~150 µm when spraying with a MAXTHAL 211^TMTi₂AlC powder of size ~38 µm in an H₂/O₂ gas flow. The films showed good adhesion to stainless steel substrates as determined by bending tests and the hardness was 3-5 GPa. X-ray diffraction (XRD) detected minority phases of Ti₃AlC₂, TiC, and Al_xTi_y alloys. The use of a larger powder size of 56 µm resulted in an increased amount of cracks and delaminations in the coatings. This was explained by less melted material, which is needed as a binding material. Second, magnetron sputtering of thin films was performed with a MAXTHAL 211^TM Ti₂AlC compound target. Depositions were made at substrate temperatures between ambient and 1000 °C. Elastic recoil detection analysis (ERDA) shows that the films exhibit a C composition between 42 and 52 at% which differs from the nominal composition of 25 at% for the Ti₂AlC-target. The Al content, in turn, depends on the substrate temperature as Al is likely to start to evaporate around 700 °C. Co-sputtering with Ti target at a temperature of 700 °C, however, yielded Ti₂AlC films with only minority contents of TiC. Thus, the addition of Ti is suggested to have two beneficial roles of balancing out excess of C and to retain Al by providing for more stoichiometric Ti₂AlC synthesis conditions. Transmission electron microscopy and X-ray pole figures show that the Ti₂AlC grains grow in two preferred orientations; epitaxial Ti2AlC (0001) // Al2O3 (0001) and with 37° tilted basal planes of Ti₂AlC (101̅7) // Al₂O₃ (0001).</p> / Report code: LIU-TEK-LIC-2008:15.