Godkänd; 1998; 20070404 (ysko)

No description available.

Godkänd; 1995; 20080330 (ysko)

Statistics shows that most traffic accidents with fatal outcome can be related to slippery road conditions. The most hazardous road conditions are the ones that are hard for the driver to detect and that appears sudden on the road. A sensor that classify the road condition in front of the vehicle, warning both the driver and the systems in the vehicle that are incorporated to help the driver, like the electronic stability program (ESP), anti-lock brake system (ABS) or the traction control system (TCS), could help to reduce these accidents. There are several prototypes for classification of road conditions available but they are not yet fully functional. In this thesis a method that makes it possible to classify the four distinct road conditions dry asphalt and asphalt covered with water, ice and snow, respectively, with a low probability of wrong classification using three wavelengths is presented. A prototype sensor built on the a technique using two laser diodes and a photo detector is tested in a real environment and compared with laboratory measurements which shows a promising result characterizing dry asphalt and asphalt covered with ice and snow. Both theory and experiments are presented. The most difficult road conditions to classify from each other are water and clear ice for which a method using polarized light is investigated. The investigation shows that using polarized light for illumination and a polarizer as an analyzer for classification of water and ice on asphalt is a more reliable method than using unpolarized light. All three investigations show promising results in developing an actual sensor to reduce fatal accidents in traffic. / Godkänd; 2007; 20071011 (ysko)

Arbetet utfördes i Vindeln hos Indexator Rotator Systems AB som är ett världsledande företag inom rotatorer. Mellan kran och rotator monteras ofta en länk, en del av dessa länkar erbjuder en viktfunktion, dessa kallas våglänk. I detta examensarbete togs en alternativ våglänk fram. Arbetet är en fortsättning på tidigare arbeten utförda av Indexator. Våglänken som togs fram använder sig av en lastcell för att mäta belastningen som uppstår när virke och dylikt lastas. Projektet kommer vara uppdelat i två delar. Den första delen handlar om att verifiera den elektriska lastcellens prestanda och funktion när den är monterad i våglänken. Här skapas en verifieringsplan och en del av verifieringen utförs även under arbetets gång. För att kontrollera lastcellens funktion så kopplas den upp mot en Arduino och en accelerometer. All programmering och tillhörande kod presenteras i rapporten. I den andra delen ritas våglänk 80–80 5t om för att acceptera den elektriska lastcellen. Innan våglänken ritas om skapas en jämförelse mellan tänkbara lastceller sett till prisbild, form samt funktion. Dessa presenteras med tillhörande offerter. Två lastceller valdes ut och två prototyper per lastcell ritades i Siemens NX. Ritningar tas fram till varje koncept för framtida prototyptillverkning. Resultatet är en jämförelse av två olika lastceller, en verifieringsplan där en del av verifieringen är utförd och CAD-filer med tillhörande ritningar. / The work was carried out in Vindeln at Indexator Rotator Systems AB, which is a world-leading company in rotators. Between the crane and the rotator a link is often mounted, some of these links offer a weight function, and are called weighing links. In this thesis, an alternative weighing link was constructed. This work is a continuation of previous work done by Indexator themselves. The weighing link developed uses a load cell to measure the load that occurs when timber and such are lifted. The project will be divided into two parts. The first part is about verifying the performance and function of the electric loadcell when mounted in the weighing link. Here, a verification plan is created and parts of the verification is also done during the work. To check the function of the load cell, it is connected to an Arduino and an accelerometer. All programming and associated code are presented in the report. In the second part, changes are made to the weighing link 80-80 5t to accept the electric load cell. Before drawing the weighing link, a comparison is made between possible load cells with regards to price, form and function. These are presented with related quotes. Two load cells were selected and two prototypes per load cell were drawn in NX. Drawings are developed for each concept for future prototype production. The result is a comparison of two different load cells, a verification plan with some verification performed and cad files with associated drawings.

Additive Manufacturing (AM) is gaining popularity in aerospace and automotive industries. This is a versatile manufacturing process, where highly complex structures are fabricated and together with topology optimization, a powerful design tool, it shares the property of providing a very large freedom in geometrical form. The main focus of this work is to introduce new developments of Topology Optimization (TO) for metal AM. The thesis consists of two parts. The first part introduces background and theory, where TO and adjoint sensitivity analysis are described. Furthermore, methodology used to identify surface layer and high-cycle fatigue are introduced. In the second part, three papers are appended, where the first paper presents the treatment of surface layer effects, while the second and third papers provide high-cycle fatigue constraint formulations. In Paper I, a TO method is introduced to account for surface layer effects, where different material properties are assigned to bulk and surface regions. In metal AM, the fabricated components in as-built surface conditions significantly affect mechanical properties, particularly fatigue properties. Furthermore, the components are generally in-homogeneous and have different microstructures in bulk regions compared to surface regions. We implement two density filters to account for surface effects, where the width of the surface layer is controlled by the second filter radius. 2-D and 3-D numerical examples are treated, where the structural stiffness is maximized for a limited mass. For Papers II and III, a high-cycle fatigue constraint is implemented in TO. A continuous-time approach is used to predict fatigue-damage. The model uses a moving endurance surface and the development of damage occurs only if the stress state lies outside the endurance surface. The model is applicable not only for isotropic materials (Paper II) but also for transversely isotropic material properties (Paper III). It is capable of handling arbitrary load histories, including non-proportional loads. The anisotropic model is applicable for additive manufacturing processes, where transverse isotropic properties are manifested not only in constitutive elastic response but also in fatigue properties. Two optimization problems are solved: In the first problem the structural mass is minimized subject to a fatigue constraint while the second problem deals with stiffness maximization subjected to a fatigue constraint and mass constraint. Several numerical examples are tested with arbitrary load histories.

This thesis is intended primarily as estimating the technical feasibility of aninvention while achieving product development for a company as a project. Theproject tries to use the invention for covering the market of urban wind turbines.Because it is a safe device for the environment and has no noise, it will beinteresting to use it in residential areas even by a low power coefficient.The project covers a wide range of readers from those who are new in the windindustries with mathematics and mechanics background until professionals. Also,consultants and wind turbine companies will be interested in, such as new ideasand solutions. The project estimates location, height, mechanical principles, andthen it evaluates feasibilities. The design distributed in three phases, head, bracingstructure, and foundation.The head consists of two counter-rotating turbines, one inside to the other and in avertical position. Generally, the mechanism of turbines follows the Savoniusturbine. However, the curved profile of the blades does not follow the semicircularfunction but is of the improved type curve. The bracing structure hasenough height to provide the specified wind speed and keep it against a strongstorm and with enough safety. The foundation has a modern structure to carryforces and momentum.The whole structure match in a triangle profile to spend low components againstthe weight, costs and life cycle energy. At the same time, the used methods in thethesis are matched to academic and industrial procedures to carry out this kind ofinvention according to product development. The main parts of the thesis arefocused on the introduction of wind turbines, methods, theory, and results. Theresults consist of designs, calculations. Finally, a conclusion, critical review, andfurther activities presented.

As the frontier of technology is pushed ever farther, the need for new and improved materials is always present. This thesis investigates the mechanical properties of compacted graphite iron (CGI) as it has been suggested as an alternative to traditional lamellar iron in truck cylinder blocks. The obtained values are compared to the mechanical properties predicted by a commercially available casting simulation software. This thesis shows that the mechanical properties vary within each CGI- cylinder block with respect to position and that the technology of casting several cylinder blocks with similar properties already exists. The casting simulation software used in this thesis was found to give conservative predictions of the evaluated mechanical properties. / i takt med att den tekniska utvecklingen går framåt ställs allt högre krav på konstruktionsmaterial. Inte minst gäller detta cylinderblock i lastbilar. Ett intressant alternativ till traditionellt lamellärt grafitjärn är kompaktgrafitjärn (CGI), som i flera avseenden har mekaniska egenskaper som är bättre lämpade för cylinderblock än det traditionella alternativet. I detta arbete kartläggs mekaniska egenskaper hos cylinderblock gjutna i CGI. De uppmätta värdena används sedan för att utvärdera ett kommersiellt gjutsimuleringsverktyg. Arbetet visar på att det är möjligt att erhålla låg spridning i mekaniska egenskaper mellan individuella block givet att ingångsparametrarna är likartade. Samtidigt går det att konstatera att det föreligger viss spridning i mekaniska egenskaper inom varje cylinderblock. Simuleringsprogrammet som utvärderats överskattade aldrig någon av de undersökta hållfasthetsparametrarna för någon av de positioner som undersökts i detta arbete. Detta är betryggande då det borgar för att simuleringsprogrammet kan komma att utgöra ett pålitligt verktyg i framtida utvecklingsarbeten.

The shear ring is dependent on a weak link that is activated in case of emergency situations. The failure of the weak link needs to be propagated in a controlled way and it is the only component in the tool that is allowed to brake. In an emergency attempt performed offshore, the current design of the shear ring did not shear at the required load. The testing of the ring was unsuccessful and the attempt caused failure instead on the surrounding parts of the main tool. The reasons behind this unsuccessful event were due to both the material and the geometry of the ring. A new design of the shear ring was proposed. The purpose of this master thesis was to evaluate the failure of both the old and new design. The theoretical analyses on the current design of the shear ring were performed with two methods; implicit and explicit. The results were compared to a physical test in order to evaluate the accuracy of the computational methods. The implicit method and the physical test provided similar results. The explicit gave slightly higher forces but it followed the same behavior as the physical test. Both experimental and theoretical analyses show that the current design of the shear ring gets stuck to the component below the ring. The value of the explicit method is the modeling of the damage and failure in a material. This cannot be performed by the implicit method. The theoretical analysis of the proposed design of the shear ring was performed with the explicit method using the shear failure model to simulate the failure of the ring. The shear failure criterion is robust and simple but this method requires a full stress train curve until failure. The proposed design of the shear ring broke in a predictable way. / Säkerhetsringen är en komponent som skall gå sönder vid olyckshändelser eller oförberedda situationer för att skydda utrustning och miljö ute i havs. Därför är det viktigt att säkerhetsringen, vid rätt kraft, går sönder på ett förutbestämt sätt. Eftersom säkerhetsringen är den enda komponenten i verktyget som får gå sönder är det väldigt viktigt att denna process är kontrollerad. Vid ett test som utfördes ute till havs så gick inte den nuvarande konstruktionen på säkerhetsringen sönder på ett förutbestämt sätt. Testet av ringen var ej lyckosamt vilket orsakade skada på de omkringliggande delarna på huvudverktyget. Anledningarna bakom det misslyckade testet berodde på både materialval och geometrin på säkerhetsringen. En ny konstruktion på ringen togs fram. Den här uppsatsen har till uppgift att utvärdera brottet av den gamla och nya konstruktionen. De teoretiska analyserna på den nuvarande konstruktionen på säkerhetsringen genomfördes med två olika metoder, implicita och explicita metoden. Resultaten jämfördes med ett fysiskt test för att säkerställa träffsäkerheten av de båda beräkningsmetoderna. Implicita metoden och det fysiska testet påvisade liknande resultat. Den explicita metoden gav en aning högre krafter men det följde samma beteendemönster som det fysiska testet. Båda det fysiska testet och de teoretiska beräkningarna visade att ringen fastnade på komponenten direkt under den. Värdet av den explicita metoden är modelleringen av brott i ett material. Detta kan inte genomföras med den implicita metoden. De teoretiska beräkningarna på den föreslagna konstruktionen på säkerhetsringen genomfördes med den explicita metoden och ’’Shear failure’’ kriteriet för att simulera hur ringen går sönder. Detta kriterium är robust och simpelt men det kräver en dragprovkurva tills brott av det material som används. Den föreslagna konstruktionen på säkerhetsringen går sönder på uträknat sätt.

This Master thesis investigates mechanical failures of electrofusion joints. This type of joints are used for weld high density polyethylene pipe systems where tting and pipe will be welded together by the heat caused by the resistance of the copper cables to electric current. There have been some failures where a brittle crack has grown through the fusion zone. Polyethylene as a material has a ductile character but brittle behavior occurs due to an unsuccessful welding by a poor fusion interface. In this study, we have chosen to investigate the plausible load cases that can cause the failure and studied the e ect of the geometry of the tting on the fracture toughness of the welded structure. We used the nite element method numerical analysis. We have approached unsuccessful welding (brittle) with a linear model and non-linear (CZM) model and successful welding (ductile) with a non-linear XFEM model. The material parameters needed for these models are gathered by series of experiments. The results shows that the inside pressure is the critical load case. The linear model and CZM model are consistent in terms of predicted responses to the geometrical parameters for the unsuccessful welding. Decreasing the inner cold zone length, increasing the fusion length and the thickness of the tting will improve the fracture toughness of the welded structure. / Detta examensarbete på masternivå handlar undersökning och simulering av brott i elektromuffsvetsar. Den har typen av svets används för att sammansvetsa rör  av högdensitiets polyeten där muff och rör svetsas samman med värmen som skapas på grund av koppartråadens motstånd mot elektrisk ström. Flera tidiga brott där en spröd spricka har växt genom svetsområdet har observerats. Polyeten som material ar duktilt men sprött beteende förekommer på grund av dålig svets och svetsgränssnitt. I detta arbete valdes att undersöka de möjliga kritiska belastningar som kan orsaka brott och påverkan av muffens geometri på brottmotstandet hos den ihopsvetsade muff- och rörstrukturen. Den numeriska finita element-metoden användes. En dålig svets (spröd) angreps med en linjar modell och en icke linjar (CZM) modell och en bra svets (duktil) hanterades med en icke linjäar (XFEM) modell. Aktuella materialparametrar identiferades genom experiment. Resultatet visar att det inre trycket är den kritiska belastningen. I termer av respons till de geometriska parametrarna, var den linjära och icke-linjära modellen (CZM) for den dåliga svetsen konsekventa. Reducerad inre kylzon, ökning av svetslängd, och öokning av mufftjocklek ökar brottmotståndet hos den ihopsvetsade strukturen.