This thesis focuses on FEM analysis of paperboard global stiffness. Simulations in Abaqus and experiments were carried out where the deformation was measured. The experimental results were compared with simulation results in order to verify the FEM simulations. Different types of boxes were used to carry out the empirical experiments. The analyses are based on one model that simulates the mechanic behavior of the used boxes. The influence of the creasing stiffness in the global stiffness is specially analyzed. Different gluing zones, materials and structural geometries were used in boxes. The model predicted the experimental results well except from the gluing zones that in some experiments had a higher impact concluding in worse results. Moreover, the results of the work indicate that the deformation of the boxes mostly depend on the bending stiffness of the paperboard while the influence of the creasing stiffness is low.

I det här arbetet undersöks hur väl Effective notch-metoden, postprocessorn FEMFAT samt en metod som utnyttjar en ekvivalent spänning i svetsens närområde predikterar svetsförbands livslängder. För att få en uppfattning om metodernas förmåga att prediktera livslängd jämförs beräknade livslängder med livslängder erhållna vid Wöhlerprovning av fyra olika geometrier av pluggsvetsförband samt ett svetsat växlingslänkage. Målet är att finna en tidseffektiv och noggrann metod för modellering av de studerade förbandstyperna, en metod som på sikt kan användas för livslängdsprediktion oberoende av svetsförbandstyp och lastfall. Resultat visar att Effective notch-metoden är en konservativ metod som inte överskattar svetsförbandens livslängder. Då Effective notch-metoden minimerar risken att man råkar ut för oväntat haveri bör den användas vid svetsförbandsutvärdering trots att det inte är den tidseffektivaste metoden. FEMFAT visar stor variation och opålitlighet i resultaten och bör inte användas för svetsförband som inte finns fördefinierade i deras modelleringsguide. Metoden med ekvivalent spänning i svetsens närområde tenderar att överskatta livslängder om komponenten utsätts för en pulserande last medan goda resultat erhålls då lasten är växlande. Då metoden är väldigt enkel att använda kan den vara ett bra verktyg för att lokalisera kritiska svetsar i stora strukturer, men anses inte lämplig för noggrannare utvärdering av svetsförband.

The oil- and gas industry has increasingly begun to switch from oil platforms and instead started to install the modules, process stations, etc. directly on the seabed. Some parts are more sensitive to external loads than others, and it is crucial to protect them to avoid damage on the structures and even gas/oil leakage. Protection covers made of glass fiber reinforced plastic (GRP) is becoming more frequently used in the offshore industry due to its low cost and good mechanical properties. Common load cases that the GRP cover could be exposed to have been identified and an investigation has been carried out to see what influence different factors like lay-up sequence and the number of plies has on the GRP cover. A fast and effective working method for future projects regarding GRP covers has been developed with the usage of Ansys and Excel. Analysis showed that for the installation and trawl net friction load cases the number of failed layers are very much dependent on the lay-up sequence of the GRP cover. Installation should be done vertically in order to prevent ply failure. For the trawl impact and Trawl Over-Pull load cases the numbers of failed plies are almost independent of the lay-up sequence. The conclusion is that lay-up sequences of [0/90]s and [-45/45]s are the most appropriate ones for this type of GRP cover and for the considered load cases. A total of 48 plies were recommended to ensure a completely intact protection structure for installation and trawl net friction, and only get small local failure at the trawl impact and over-pull load cases.

Detta examensarbete undersöker armeringens inverkan på en förankringsskruvs utdrags-kapacitet. Simuleringar har genomförts i finita elementprogrammet Abaqus. Studien behandlar ett betongblock, 1.2x1.2x0.3 m, med en förankringsskruv i mitten av blocket. Skruven har en diameter på 30 mm och är 220 mm lång, varav de nedersta 20 mm omges av en mutter med diametern 45 mm. Undersökningar har gjorts för att se hur ytarmering påverkar konstruktionens kapacitet och hur, när och var det kommer spricka upp. Armeringen har lagts in som ett rutnät i både överkant och underkant av betongblocket och har varierats i täthet. För att skapa en bra modell har förberedande undersökningar gjorts på materialmodell, mesh, elementtyp, elementstorlek och om det går att förenkla modellen genom att ersätta skruven med randvillkor. Studien har sedan genomförts för sex olika fall av armeringstäthet. Resultatet visar att ju tätare armering desto mer utdragslast kan förankringsskruven ta upp. Avståndet mellan armeringen och förankringsfästet påverkar också. Ligger första armerings-stången nära förankringen klarar konstruktionen en större belastning än om armeringen är placerad längre ifrån. Plottar över största plastiska huvudtöjningen indikerar hur mikrosprickor kommer att ut-vecklas i betongen med start nära skruvskallen och med formen av en kon. Det finns också tendenser till att lutningen på konen blir brantare ju tätare armeringen är.

In this master thesis project the possibility to model the response of a wing when subjected to bird strike using finite elements is analyzed. Since this transient event lasts only a few milliseconds the used solution method is explicit time integration. The wing is manufactured using carbon fiber laminate. Carbon fiber laminates have orthotropic material properties with different stiffness in different directions. Accordingly, there are damage mechanisms not considered when using metal that have to be modeled when using composites. One of these damage mechanisms is delamination which occurs when cured layers inside a component become separated. To simulate this phenomenon, multiple layers of shell elements with contact in between are used as a representation of the interface where a component is likely to delaminate. By comparing experimental and simulated results the model of delamination is verified and the influence of different parameters on the results is investigated. Furthermore, studies show that modeling delamination layers in each possible layer of a composite stack is not optimal due to the fact that the global stiffness of the laminate is decreased as more layers are modeled. However, multiple layers are needed in order to mitigate the spreading of delamination and obtain realistic delaminated zones. As the laminates are comprised of carbon fiber and epoxy sheets it is of importance to include damage mechanisms inside each individual sheet. Accordingly, a composite material model built into the software is used which considers tensile and compressive stress in fiber and epoxy. The strength limits are then set according to experimental test data. The bird is modeled using a mesh free technique called Smooth Particle Hydrodynamics using a material model with properties similar to a fluid. The internal pressure of the bird model is linked to the change in volume with an Equation of State. By examining the bird models behavior compared to experimental results it is determined to have a realistic impact on structures. A model of the leading edge is then subjected to bird strike according to European standards. The wing skin is penetrated indicating that reinforcements might be needed in order to protect valuable components inside the wing structure such as the fuel tank. However, the results are not completely accurate due to the fact that there is little experimental data available regarding soft body penetration of composite laminates. As a consequence, the simulation cannot be confirmed against real experimental results and further investigations are required in order to have confidence in modeling such events. Furthermore, the delamination due to the bird strike essentially spreads across the whole model. Since only one layer of delamination is included the spread is most likely overestimated.

Schlumberger drilling tools are exposed to very hard loading conditions (shocks, vibrations, thermal cycling) while performing a job. As these tools are full of electronics, issues can quickly come from electronics failure. Mechanisms of failure occurring in electronics are very complex but can be predicted in some cases. The first part of the thesis describes in which context mechanical engineering applied to electronics is used in Schlumberger. The different kinds of failure which will be investigated in the report are presented in this part. The second part deals with fatigue models used in electronics. From classical methods used in mechanical engineering to calculate a material fatigue life, fatigue models are adapted and formulated for special applications. The third part investigates the issue of capacitor flex-cracking which occurs when boards do not remain flat during loadings (shocks or thermal cycling). Root causes of this mechanism of failure are investigated in this part to find key points where improvements have to be made to avoid failure. The fourth part presents a common failure which deals with Plated Through Holes (PTHs) issues. A simple model of investigations is established. The fifth part deals with fatigue life of leadless components (resistors) under thermal cycling. Even if the failure is revealed during shock tests, the damage is mostly created during the thermal cycles applied on the board prior to shock. The effect of the size of the component is discussed in this part. The last part deals with modal analysis on a given board in order to be able to reduce the impact and the damage of shocks applied on this board. Simulation and experimental modal analysis are compared in order to see the influence of certain parameters on the natural frequencies of the board.

Försvarsmakten har köpt in en ny typ av ammunition till Ak 5 och Ksp 90, miljöammunition. Den nya ammunitionen har en stålkärna istället för en blykärna. För att vikten på projektilen skall vara den samma har projektilen gjorts något längre. Eftersom stål har andra materialegenskaper än bly kommer den nya projektilen (5,56 mm sk ptr 5B stkprj) att studsa, rikoschettera annorlunda än den gamla. Rikoschetter utgör en risk för såväl egna förband som tredje person vilket gör att det är av största vikt att förstå fenomenet, försöka minimera sannolikheten för att rikoschett ska uppstå och att uppdatera säkerhetsföreskrifterna. Försvarsmakten har under 2011 initierat ett rikoschettprojekt på FOI med inriktning mot finkaliberammunition och riskområdesberäkningar. Inom ramen för detta behövs modeller för att kunna förutsäga risken för rikoschett mot olika målmaterial. Detta examensarbete syftar till att ge en analys av tillgängliga rikoschettmodeller med fokus på vilka fall som kan hanteras, vilka indata som krävs och vilka resultat modellen kan förutsäga (t.ex. rikoschettvinkel och hastighetsminskning). Då tillgången till användbara modeller visat sig vara begränsad har ett arbete påbörjats för att fastställa olika parametrars inverkan på rikoschettutfallet. Den parameter som bedömdes intressantast att börja med var projektilkärnans hårdhet, dels därför att den sannolikt har stor betydelse för rikoschetten, dels för att den nya miljöammunitionen har ett annat kärnmaterial än den gamla och dels för att kärnmaterialet i hotammunition varierar avsevärt. Den experimentella studien visade på en klar korrelation mellan ökad hårdhet och ökad rikoschettvinkel, en hårdare projektil studsar mer än en mjukare. Den visade även på att hårdheten inte har en inverkan på rikoschetthastigheten. Den numeriska studien ger en användbar skattning med ett fel på ca 0 till 10 %. De empiriska modellerna var inte tillräckligt tillförlitliga för att göra användbara skattningar av varken rikoschetthastigheten eller rikoschettvinkeln.

Fragments from explosive device have been and still are a great threat, but has now changed into terrorist attacks involving IED (Improvised Explosive Devise) rather than hostile forces. This master thesis will show the effects on concrete plates (50 mm depth) impacted by different projectiles, which should replicate fragments hitting buildings. The projectiles used were the 8 mm sphere, the 6 mm sphere, the 8 mm cylinder (RCC) and the FSP (fragment simulating projectile). The thesis was made at request from FOI (Swedish Research Defiance Agency) at Grindsjön and it contains both experiments made there and numerical simulations. The experiments were conducted at Grindsjön, the projectile were fired in velocities between 800 m/s and 1600 m/s. The 8 mm and RCC obtains higher penetration depth at lower velocity, while the FSP, due to its soft material, will need much higher velocity. Full penetration was obtained at 1510 m/s for the 6 mm sphere, 1310 m/s for the 8 mm sphere and 950 m/s for the RCC. The simulations were made in LS-DYNA using a meshfree solver (SPH) and the results shows that the RCC creates a bigger initial elastic wave, which will make the concrete block crack more, but it will also make the projectile lose more kinetic energy resulting in lower penetration depth in the concrete. The spherical projectiles have higher penetration depth, but it gives smaller elastic waves resulting in less cracking of the concrete. The simulations overestimate the penetration depth for the non-flat projectiles while giving good agreements for the flat projectiles, also the damage pattern are consistent with the experiments. An actual fragment from a grenade was obtained and simulated showing that all of the projectile except the RCC shows good agreements and therefore the RCC should not be used in simulating fragments.

It has a long been known that many, if not all, diseases are associated with changes in the mechanical properties of cells. Although these changes in tissue mechanics have been believed to be a conseguence of the disease, recent data show that alterations of these mechanical properties have potent eect to many cellular functions. Thus, there is no reason to believe that altered cellular mechanics could be a cause of the disease, rather than its consequence. A complete understanding of cell mechanics and how the latter one depends on the presence of a disease is therefore necessary in order to develop methods of early diagnosis. In this master thesis we report the preliminary results of cell mechanical response of broblasts obtained simulating AFM (Atomic Force Microscopy) with COMSOL 4.1. Specically, we tried to nd out what is the relationship that coexists between the reaction force of a broblast when urged by this type of technique. A subsequent process of reverse engineering led to a simply analytical model for the quantication of the mechanical properties of this type of cell. The second part of this work aims to improve the understading of the mechanotrasduction mechanism of cells. The second model, indeed, reports the results of soft concact and adhesion of a broblast with a polyacrylamide substrate. Finally, we built up a numerical model that combines the assumptios of the rst and the second one.

In this thesis the influence of the drying pressure on interfibre bond strength was investigated. Five different drying pressures, 0.7, 2.9, 4.5, 6.7, and 15 kPa, were applied during the preparation of fiber-fiber cross test pieces. The nominal overlap area of each fibre-fibre cross was measured in a transmission light microscope. A tensile tester was used to record the loaddeformation behavior of each fiber-fiber cross. The final results of the interfibre bond strength were defined by both the overlap area and the maximum force of each bond. The results showed that the influence of drying pressure to the average strength were very weak, although a maximum could be seen at 2.9 kPa of drying pressure. Moreover, the results suggested the overall trend of decreasing strengths at very high drying pressures. Finally, a statistical significance study of the results was presented. In addition, the influences of fiber type (spring wood vs. summer wood) and press type (steel vs. steel or steel vs. rubber) on interfibre bond strength were also discussed.