To be able to verify that a cylinder head design meats the expectations a good test method is needed. The aim of this thesis is to determine the best way of testing with respect to validity, cost, time consumption, quantity of tested material and repeatability. The base of the new method is the current single head method and this have been expanded to the suit the cylinder head of a seven litre engine currently in production. In order to determine how many cylinders to test and the order of these simulations of fatigue have been performed. Comparing these different ways of testing was done with a comparison of the safety factor against fatigue in a reference case composed of the ignition sequence and 17 feasible test methods. From the simulation results two suitable test fixtures have been designed in Catia. A method composed of two phases of pulsation with cylinders 1, 3 and 5 in the first phase and 2, 4 and 6 in the second phase is suggested as test method.

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UMV är ett företag som konstruerar och tillverkar bestrykningsmaskiner till papper och kartongindustrin. På dessa pappersmaskiner finns det en schaber monterad, som har till uppgift att skrapa av en vals från smuts och bestrykningsmaterial. I dagsläget köps denna schaber in som ett färdigt system, medan många av de resterande delarna till bestrykningsmaskinen konstrueras av UMV och tillverkas av underleverantörer. UMV vill undersöka vad kostnaderna skulle bli om de själva skulle konstruera och tillverka en schaber vilket är orsaken till att detta examensarbete har skapats. Projektets huvudsakliga målsättning har varit att ta fram ett koncept på en schaber som är billigare än nuvarande inköpta schaber. Konstruktionen har utvecklats mot den kravspecifikation som har tagits fram i arbetet. Projektet inleddes med att en projektplan och en tidsplan skapades. Sedan undersöktes hur en bestrykningsmaskin fungerar. Vidare undersöktes även valet av lagring för schabern samt materialval. Efter detta steg framställdes olika koncept med hjälp av olika idégenereringsverktyg och ett koncept valdes sedan med hjälp av konceptvalsmatriser. Efter detta steg konstruerades hela schabern i ett CAD-program och ritningar framställdes för alla komponenter. Ritningar skickades sedan till UMV’s lokala leverantör CS produktion för att få offerter och en välgrundad kostnadskalkyl för konceptet. Målet med projektet har uppfyllts och schabern som har konstruerats uppfyller kravspecifikationen samt understiger kostnadskravet.

The knowledge of the dynamic behaviour of a milling process is very important for finding an optimum process window. In today's manufacturing industry the machining parameters are often predicted using experimental data from non-rotating spindles. Many times the predicted machining parameters prove to be ineffective and inaccurate which lead to reduced quality of the machined surface, tool wear, noise or at worst spindle failure. The best way to study the dynamics of the milling spindle is of course to measure the spindle response under actual operating conditions. Laser vibrometry is a non-contact, non-disturbing method commonly used for measurements of vibrations on static objects. The technique offers the possibility to measure vibrations on thin-walled (light), and rotating objects as well as sound fields. However, two major problems occur when measuring on rotating spindles: (1) speckle noise and (2) crosstalk between the vibration components. These two drawbacks make vibration measurements on rotating spindles difficult to interpret. In this Licentiate thesis the principles of laser vibrometry is introduced and the speckle noise and the crosstalk between the velocity components of a rotating spindle is studied experimentally. The rotating spindle is excited by an adaptive magnetic bearing and the response is measured by laser vibrometry and non-contact inductive displacement sensors simultaneously. The work shows that by polishing the measurement surface optically smooth we are able to avoid the speckle noise and the crosstalk problem. By using this approach, the vibrations as well as the roundness of the measured target can be resolved. Hence, the laser vibrometry technique can be used for measuring the spindle dynamics under operating conditions. Measurements on a bowed violin are performed. The chain of interacting parts of the played violin is studied: the string, the bridge and the plates as well as the generated sound field. The string is excited using a rotating bow apparatus and the vibrations from the string transmits to the violin body via the bridge and produces the sound. The measurements on the string shows stick-slip behaviour and the bridge measurements show that the string vibrations transmit to the bridge both in the horizontal and the vertical direction. Measurements on the plates show complex deflection shapes which are a combination of different eigenmodes. The sound fields emitted from the violin were measured and visualized for different harmonic partials of the played tone. However, the visualized sound field obtained by the laser vibrometer is a projection of the sound field along the laser light and the image obtained is a 2D map of the real 3D sound field. This effect is illustrated by measurements of a sound field emitted from three ultrasound transducers.

The growing effort to reduce vehicle weight and improve passive safety in the automotive industry has drastically increased the demand for ultra high strength steel components. There exist several production methods for such components, where the press hardening technique (hot stamping) is one of the most successful in producing complex components from boron steel. In order to accurately perform numerical Finite Element (FE) simulations of the actual thermo-mechanical forming, it is crucial to use correct material data and models. This work is focusing on two main aspects of the material characterisation as follows. The first is the flow stress of the austenite at elevated temperatures and different strain rates, relevant for the process, which is crucial for correctly predicting the strains in the component and the forming force. During a press hardening cycle, the actual forming is performed at high temperatures and the steel is in the austenitic state. The second, the austenite decomposition into daughter products such as ferrite, pearlite, bainite or martensite is a function of the thermal and mechanical history. To find the mechanical response (flow stress) for the austenite, a method based on multiple overlapping continuous cooling and compression tests (MOCCCT) in combination with inverse modelling has been developed. A validation test (in combination with the compression tests) shows good agreement with the simulated forming force, indicating that the estimated flow stress as a function of temperature, strain and strain rate is accurate in the actual application. The austenite decomposition model is developed and integrated as a material subroutine into the FE-code LS-DYNA. The model is based on the combined nucleation and growth rate equations proposed by Kirkaldy. A separate test to simulate different cooling histories along a boron alloyed steel sheet has been conducted. / Godkänd; 2004; 20070128 (ysko)

This Licentiate of Engineering thesis is a product of the results generated in the research project KME-702, which comprises modelling, microstructure investigations and material testing of cast nickel-base superalloys. The main objective of this work is to model the fatigue crack propagation behaviour in single-crystal nickel-base superalloys. To achieve this, the influence of the crystal orientations on the cracking behaviour is assessed. The results show that the crystal orientation is strongly affecting the material response and must be accounted for. Furthermore, a linear elastic crack driving force parameter suitable for describing crystallographic cracking has been developed. This parameter is based on resolved anisotropic stress intensity factors and is able to predict the correct crystallographic cracking plane after a transition from a Mode I crack. Finally, a method to account for inelastic deformations in a linear elastic fracture mechanics context was investigated. A residual stress field is extracted from an uncracked finite-element model with a perfectly plastic material model and superimposed on the stress field from the cracked model with a linear elastic material model to account for the inelastic deformations during the determination of the crack driving force. The modelling work is validated by material testing on two different specimen geometries at different temperatures. This Licentiate of Engineering thesis consists of two parts, where Part I gives an introduction and background to the research area, while Part II consists of three papers. / Denna licentiatavhandling är en produkt av resultat som genererats i forskningsprojektet KME-702, och omfattar modellering, mikrostrukturundersökningar och materialprovning av gjutna nickelbaserade superlegeringar. Huvudsyftet med detta arbete är att modellera sprickförloppet under utmattning i enkristallina nickelbaserade superlegeringar. För att uppnå detta har kristallorienteringens inverkan på sprickbeteendet utvärderats. Resultaten visar att kristallorienteringen har en stark inverkan på materialbeteendet, således måste hänsyn till denna tas. Dessutom har en linjär-elastisk sprickdrivkraftsparameter lämplig att beskriva kristallografisk sprickbildning utvecklats. Denna parameter är baserad på anisotropa spänningsintensitetsfaktorer på kristallplan och kan prediktera det korrekta kristallografiska sprickplanet efter övergång från Modus I spricka. Slutligen har undersökts en metod för att ta hand om inelastiska deformationer i en linjär-elastisk brottmekanikskontext. Ett restspänningsfält extraherades från en osprucken finita element modell med en ideal plastisk materialmodell. Denna överlagrades på spänningsfältet från den spruckna modellen, som analyserades med en linjär-elastisk materialmodell, för att ta hänsyn till de inelastiska deformationerna vid bestämning av sprickdrivkraften. Modelleringsarbetet validerades genom materialprovning på två olika provgeometrier vid olika temperaturer. Licentiatavhandlingen består av två delar, där del I ger en introduktion och bakgrund till forskningsområdet medan del II består av tre papper. / Dieses Lizentiat der Ingenieurwissenschaften ist im Rahmen des Forschungsprojekts KME-702 entstanden, welches Modellierung, Mikrostrukturuntersuchungen und Materialtests von gegossenen nickelbasierten Superlegierungen umfasst. Das Hauptziel dieser Arbeit ist die Modellierung der Ermüdungsrissausbreitung in einkristallinen nickelbasierten Superlegierungen. Um dieses zu erreichen, wurde der Einfluss der Kristallorientierungen auf das Rissverhalten untersucht. Die Ergebnisse zeigen, dass die Kristallorientierung das Materialverhalten stark beeinflusst und daher berücksichtigt werden muss. Darüber hinaus wurde ein linear elastischer Rissantriebskraftparameter entwickelt, der zum Beschreiben von kristallographischen Rissen geeignet ist. Dieser Parameter basiert auf aufgelösten anisotropen Spannungsintensitätsfaktoren und ist in der Lage, die korrekte kristallographische Rissebene nach einem Übergang von einem Modus I Riss vorherzusagen. Abschließend wird in einem linear-elastisch bruchmechanischen Kontext eine Methode untersucht, die nichtelastischen Deformationen bei der Bestimmung der Rissantriebskraft zu berücksichtigen. Dazu wird aus einem Finite-Elemente Modell, welches keinen Riss aufweist und mit einem perfekt plastischen Materialmodell beschrieben wird, das Restspannungsfeld extrahiert und dem Spannungsfeld überlagert, welches aus dem Modell mit Riss unter Verwendung eines linear elastischen Materialmodells erzeugt wurde. Die Modellierung wird durch Materialtests an zwei verschiedenen Probengeometrien bei unterschiedlichen Temperaturen validiert. Dieses Lizentiat der Ingenieurwissenschaften besteht aus zwei Teilen, wobei Teil I eine Einführung und einen Hintergrund in das Forschungsgebiet gibt, während Teil II aus drei Forschungsartikeln besteht.

The mechanical properties of Bohus granite subjected to contact loading is investigated based on experimental and numerical results. An elasto-plastic constitutive material model combined with a damage description is employed. The material model parameters are determined based on experimental results. Any kind of inelastic deformation except the tensile failure is described by a linear Drucker-Prager (DP) plasticity model with variable dilation angle. As for the damage description, an anisotropic damage model (DFH model) is considered to account for the tensile failure (i.e. mode I fracture). The resulting constitutive model is implemented numerically to simulate the mechanical behavior of the material under indentation loading up to its load capacity.  In paper A, the DP material model parameters are calibrated based on quasioedometric tests performed in an earlier work. It is described how the yield surface and dilation angle are determined from this test. The calibrated material model is implemented numerically in a commercial finite element software. The numerical model is validated based on quasi-static spherical indentation tests performed in this work. The force-penetration (P-h) response of the material is recorded during the indentation tests. Moreover, a high speed camera is utilized to observe the specimen surface around the contact area during the indentation test. It is detected that the observed load-drops in the P-h response correspond to material removals on the specimen surface. The tested specimens are also scanned by X-ray tomography to investigate the fracture pattern.   In paper B, the anisotropic DFH damage model is employed in order to predict the fracture pattern observed in the indentation test. The chosen damage model considers the heterogeneity in the material tensile strength. It is described how the statistical distribution of the tensile strength is calibrated. The calibrated DFH model is combined with the DP model and the resulting DP-DFH model is utilized to simulate the P-h response and the fragmentation process of Bohus granite subjected to quasi-static contact loading. / <p>Examinator: Professor Mårten Olsson, KTH, Stockholm</p><p>QC 20191108</p>

Cleavage fracture is a catastrophic phenomenon as it is a sudden structural collapse occurring to structures made of insufficiently ductile steels working at lower temperatures. In this study, the focus is on the material used in reactor pressure vessels (RPV) in nuclear power plants. The steel is exposed to radiation that by time causes embrittlement of the material. Safe operation of the power plant with today's engineering standards is possible by taking advantage of warm pre-stressing (WPS) effects. Welding is an inevitable part of manufacturing; therefore, it is important to investigate the influence of residual stresses (RS) due to welding on the load-bearing capacity of cracked components. Additionally, these stresses can also affect the benefits of WPS cycles which as mentioned earlier improves the structure behavior. In this study, the effects of two mechanisms in WPS on a RS field will be studied and compared. As the focus of the study is on the brittle fracture, a probabilistic model made by Kroon and Faleskog, will be used. To get an overview of the thesis, a summary of each topic will follow.

The demand of stronger and lighter constructions are rapidly growing. Today's applications vary over a large range industries where the requirements are di_erent from product to product. Therefore, the focus of much research are the 3rd generation of so called Advance High-Strength Steels (AHSS). These are high-strength steels that are taylormade to get desired mechanical properties. One AHSS manufactured by SSAB is their Strenx 1100Plus steel that is specially design to get excellent welding properties. In this project it was investigated if the two post weld treatments TIG dressing and HFMI has a larger e_ect in the material then the recommendations for steel in general by the International institute of Welding (IIW). By comparing nominal fatigue stresses to standards it could be determined that the post treatment improves the fatigue life with 1 more fatigue class then the recommendations for each treatment. E_ective notch stress simulations was used to derive S-N curves for comparative reasons. / Efterfrågan av starkare och lättare konstruktioner har kraftigt ökat. Dagens tillämpningar omfattar många olika industriområden där kraven varierar från varje produkt. Detta har lett till att mycket resurser idag läggs på forskning inom utveckling av tredje generationen Advance High-Stength Steels (AHSS). Ett AHSS tillverkat av SSAB är deras Strenx 1100Plus som är specialdesignat stål för att få ultimata svetsegenskaper. I detta projektet undersöktes det om efter behandlingsmetoderna TIG omsmältnings och High Frequency Mechanical Impact (HFMI) ger större effekt i materialet än vad rekommendationerna för stål generellt sett av Internationella Institutet för Svetsning (IIW) säger. Genom att jämföra nominella utmattningsspänningar med standardvärden kunde detta bekräftas. Resultatet av testerna visade att de två efterbehandlingsmetoderna ger ytterligare en utmattningsklass förbättring än vad IIW rekommenderar. För att kunna jämföra simuleringar mot dessa resultat gjordes S-N kurvor med effective notch stress metoden (ENS).

With the help of modern computational power it has become much more common to employ simulation driven development. When performing simulations before creating prototypes and actual test, companies can reduce both the time spent on the development and the cost. To get an as accurate model as possible one would ideally include all of the physics involved - in order to allow simulation of all potential scenarios and hence create a digital twin. When having a sufficiently complex model it is easy to perform simulations and thereafter give feedback to the designer, without having to build prototypes. The aim of this project has been to create a model which captures the multiphysics of a handheld tightening tool provided by Atlas Copco. The tool contains an electric AC permanent magnet motor which through electromagnetism creates an oscillating torque acting on the rotor. The mechanical response of the driveline in the tool due to the variations in the torque was to be analysed. The modelling of the system was split into two parts; one electromagnetic analysis concerning just the motor and one dynamic analysis concerning the driveline of the tool in order to find the arising vibrations. To detect which frequencies the system should be sensitive to, a modal analysis was performed - yielding among others a torsional mode at 3276 Hz. For investigating for which frequencies the model – with applied forces and boundary conditions - is sensitive to, a velocity ramp up test was performed. A prominent peak was detected at 3200 Hz which corresponds to the previously observed torsional mode at the same frequency. It could thus be concluded that the system is sensitive to rotor velocities of 32 000 rpm since this causes axial vibrations in the bevel gear of the tool. Some improvements to the model could be made, but in order to make an even more accurate model of the tool a time span exceeding the one intended for the project would be required. / Tack vare dagens moderna datorhjälpmedel har det blivitmycket mer vanligt att använda sig av simuleringsdriven utveckling. När simulering utförs innan skapandet av prototyper och riktiga tester kan företag reducera både tiden som spenderas på utvecklingen samt den totala kostnaden. För att skapa en så precis modell som möjligt är det idealt att inkludera all fysik som är inblandad - för att möjliggöra simulering av alla potentiella scenarion. När en tillräckligt komplex modell är skapad är det enkelt att utföra simuleringar och därefter ge återkoppling till konstruktören, utan att behöva bygga prototyper. Syftet med det här projektet var att skapa en modell som fångar multifysiken hos ett handhållet åtdragningsverktyg, försett av Atlas Copco. Verktyget innehåller en elektrisk, AC, permanent magnet motor som genom elektromagnetism skapar ett oscillerande moment verkande på rotorn. Den mekaniska responsen som uppkommer i verktygets drivlina på grund av variationerna i momentet skulle analyseras. Modelleringen av systemet delades in i två delar; en elektromagnetisk modell som endast innefattade motorn samt en dynamisk modell som innefattade drivlinan i verktyget för att kunna observera de uppkommande vibrationerna. För att detektera vilka frekvenser systemet bör vara känsligt mot genomfördes en modalanalys - vilken uppvisade bland annat en torsionsmod vid 3276 Hz. För att sedan kunna undersöka för vilka frekvenser modellen - med applicerade krafter och randvillkor - är känsligt mot, genomfördes ett test där vinkelhastigheten på rotorn rampades upp. En framträdande resonanstopp upptäcktes vid 3200 Hz, vilket sammanfaller med den tidigare observerade torsionsmoden vid samma frekvens. Det kunde därför som slutsats konstateras att systemet är känsligt mot rotorhastigheter på 32 000 rpm då detta orsakar axiella vibrationer i vinkelväxeln i verktyget. Några förbättringar på modellen kan genomföras för att skapa en ännu mer precis modell av verktyget, men detta skulle kräva ett längre tidsspann för projektet än vad intentionen var.