Föreliggande studie omfattar sättningsberäkningar med den senaste kommersiella versionen av datorprogrammet FEM-Design 12, utvecklat i samverkan mellan konstruktörer och geotekniker.Programmet är en uppföljare till den tidigare versionen FEM-Design 11 och även en förbättring av den betaversion 12, som fanns tillgänglig och under utveckling fram tills att den första kommersiella versionen av FEM-Design 12 lanserades under hösten 2013. Tidigare studier har gjorts av en Betaversion 12 i form av ett examensarbete, där jorden modellerades med volymelement, enligt kontinuumsmekanik. Resultaten i studien påvisade en stor procentuell sättningsdifferens (22 %) jämfört med sättningsberäkningar i det geotekniska programmet PLAXIS. Denna procentuella skillnad kan antingen bero på att själva byggnaden inte kan modelleras i PLAXIS och därmed inte kunde beaktas i beräkningarna, eller att det fanns brister i betaversionen FEM-Design 12, vilka gjorde att resultaten som uppvisades inte var rättvisande.I denna naturliga fortsättning har nya beräkningar gjorts med hjälp av den senaste kommersiella versionen av FEM-Design 12 för att validera sättningarna i en ny pilotstudie och undersöka om rimliga resultat erhålls. Som en del av denna jämförelse och värdering har även sättningsberäkningar för hand utförts.Interaktionen mellan FEM-Design och användarna har granskats för att se hur brukarna upplever den nya versionen samt om programmet uppfyller de mål som formulerades i samband med utvecklingsarbetet. Tre olika projekt har modellerats i FEM-Design 12 där jorden beskrivs med finita element (volymelement). / The present study includes settlement calculations with the latest commercial version of the computer program FEM-Design 12, developed in collaboration between geotechnical- and structural engineers.The program is a sequel to the earlier version FEM-Design 11 and also an improvement of the beta version 12, which was available and under development until the first commercial version of FEM-Design 12 was launched in autumn 2013.Previous studies have been made of a Beta version 12 in the form of a study, where the soil was modeled with volume elements, according to continuum mechanics. The results of this study demonstrated a large percent set difference (22 %) compared to settlement calculations in the geotechnical computer program PLAXIS. This percentage difference could either be due to that the building itself cannot be modeled in PLAXIS and thereby could not be considered in the calculations, or that there were deficiencies in the beta version FEM-Design 12, which led to that the results exhibited were not accurate.In this natural continuation, new calculations have been made by using the latest commercial version of FEM-Design 12 to validate the settlements in a new pilot Study and examine whether reasonable results is obtained. As part of this comparison and evaluation, hand calculations have been performed.The interaction between FEM-Design and the users have been examined to see how the users experience the new version and whether the program meets the objectives formulated in the context of the development work.Three different projects have been modeled in FEM-Design 12 where the soil is described by finite element (volume elements) will be used.

Reinforced concrete slabs are a conventional type of foundation that is widely used in residential, commercial and industrial buildings. Most of the slab foundations are constructed directly on the ground without another structural medium in between and some of the slabs are therefore influenced by ground softening. A slab foundation is designed to transfer vertical loads and bridge imperfections in the ground, but excessive soil distortion may destroy the support conditions of the slab and through this influence the stability of the superstructures. The aim of this project is to study how ground softening and its further development influence a typical concrete slab. Furthermore, an approximate analytical method to evaluate the condition of a slab due to ground softening was studied. A practical case has been studied to capture the actual failure behaviours of a reinforced concrete slab, based on a previous project. For the case studied, possible future mining activities close to a high bay warehouse may cause damaging settlement in the underground. The fault that may appear softens the soils underneath the foundation, which may deteriorate and cause collapse of the concrete slab under the warehouse. Two types of failure scenarios were studied; subsoil softening and subsoil collapse. The Finite Element Method (FEM) was used to analyse the behaviour of the slab and the development of the failures in the subsoil. A commercial FEM software package, Abaqus, was used as the analytic tool, with a built-in Concrete Damaged Plasticity model (CDP) that for the concrete material model. Both linear and nonlinear material properties have been used in the analyses with same softening effect of the subsoil. A large number of models were analysed to simulate the development of the fault and capture the failure modes of the slab at different stages. Excessive tensile cracks and vertical deformations were found in both failure scenarios studied. A possible internal stability problem of the warehouse due to this was also found. The nonlinear behaviour of the concrete slab was captured through the failure scenarios before damage. It is shown that the serviceability of the reinforced concrete slab can be influenced by softening ground, and a more realistic description of the possible failures was here obtained based on the nonlinear model compared to previous elastic analyses. Keywords:     Reinforced concrete slab, Nonlinear, Ground softening, Finite Element Method (FEM), Abaqus, Concrete Damaged Plasticity (CDP). / Armerade betongplattor är en vanlig typ av fundament som ofta används för bostäder, kommersiella och industriella byggnader. De flesta av grundplattorna konstrueras direkt på marken utan andra strukturella medium emellan och vissa av plattorna påverkas därför av mjuknande undergrunder. En grundplatta är konstruerad för att överföra vertikala laster och överbrygga imperfektioner i marken, men stora sättningar i undergrunden kan förstöra plattans stödförhållanden och genom detta störa stabiliteten för överbyggnaderna. Syftet med projektet är att studera hur mjuknande undergrund och dess propagering påverkar en typisk betongplatta. Vidare används en approximativ analysmetod för att utvärdera tillståndet hos en platta på sådan mark. Ett praktiskt fall har studerats för att fånga det verkliga brottbeteendet hos en armerad betongplatta, vilket bygger på ett tidigare genomfört projekt. För det studerade fallet kan eventuell framtida gruvdrift nära ett höglager orsaka skadliga sättningar i undergrunden. Den förkastning som kan uppstå kan leda till uppmjukning av jordarna under fundamentet, vilket kan förvärras och orsaka kollaps av betongplattan under lagret. Två typer av brottscenarier studerades; uppmjuknande respektive full kollaps av undergrunden. Finita Element Metoden (FEM) användes för att analysera beteendet hos plattan och utvecklingen av fbrott och förskjutning i undergrunden. Ett kommersiellt FEM programpaket, Abaqus, användes som analytiskt verktyg, med en inbyggd plasticitets och skademodell (CDP) för att beskriva betongmaterialets egenskaper. Både linjärelastiska och icke-linjära materialegenskaper har använts i analyserna, för att simulera effekten av den mjukande undergrunnden. Ett stort antal modeller analyserades för att simulera skadepropageringen och fånga brottmoder i plattan genom olika skeden. Dragsprickor och vertikala deformationer uppstod i bägge de studerade scenariorna. Ett möjligt intern stabilitetsproblem hos lagret på grund av detta konstaterades också. Det olinjära beteendet hos betongplattan fångades fram tills allvarlig skada uppstod. Det visas att funktionen i bruksgränsstadiet hos den armerade betongplattan kan påverkas genom uppmjuknande undergrund, och att en mer realistisk beskrivning av möjliga brott här kunde erhållas genom den olinjära modellen, jämfört med tidigare elastiska analyser. Nyckelord:   Betongplatta , Icke-linjärt uppträdande, Finita Element Metoden (FEM), FE-modell, Abaqus, Plasticitets och skademodell för betong (CDP).

Tissue paper is a type of soft, absorbent, and lightweight paper with several applications for hygiene and kitchen use. Embossing is an operation during the converting stage of the tissue production process which creates relief designs on tissue. Other than producing designs for aesthetic purposes, embossing increases bulk which improves absorbency and softness but reduces mechanical strength and stiffness. A computational model using the finite element method is developed to simulate the embossing of tissue paper. A tool for fitting an appropriate material model for tissue to its experimental test data is implemented. The material model is subjected to a verification test and it works sufficiently well to model the in-plane elastic and plastic anisotropic behavior of tissue. Two validation tests are conducted to check the embossing model against experimental test data where it is observed that the model works well. Firstly, it provides an idea about the amount of pressure required to be applied during loading to reach a certain embossing level. Secondly, it predicts the tensile strength of embossed tissue sheets although it provides a slight underestimate. Potential reasons for the shortcomings in the tensile strength are suggested and recommendations for further improving the model are provided. Lastly, parametric studies are conducted to investigate the influence of embossing pattern geometry on the mechanical performance of embossed tissue.  After passing the verification and validation stages, the model is ready to serve as a convenient, less time-consuming, and cost-effective alternative to experimental testing to study the embossing process. It can also be used as a tool to examine the effect of one or more model parameters on embossing by simply changing them and studying the new results. / Mjukpapper är ett mjukt och absorberande papper med låg ytvikt för hygien- och köksändamål. Prägling är en operation under konverteringsstadiet av produktionsprocessen som skapar reliefmönster på mjukpapperet. Förutom att skapa mönster för estetiska ändamål, ökar präglingen bulken som förbättrar absorptionskapacitet och mjukhet men den minskar mekanisk styrka och styvhet.En beräkningsmodell med finita element-metoden utvecklas för att simulera prägling av mjukpapper och ett verktyg för att koppla en lämplig materialmodell för mjukpapper till dess experimentella testdata implementeras. Materialmodellen genomgår ett verifieringstest och det fungerar tillräckligt bra för att modellera det elastisk-plastiska anisotropiska beteendet hos mjukpapper i planet. Två valideringstester utförs för att kontrollera präglingsmodellen mot experimentella testdata där det observeras att modellen fungerar bra. För det första ger den en uppfattning om mängden tryck som behöver appliceras för att nå en viss präglingsnivå. För det andra förutspår den draghållfastheten hos präglade mjukpappersark även om det ger en liten underskattning. Potentiella orsaker för bristerna i draghållfasthet föreslås och rekommendationer för ytterligare förbättringar av modellen ges. Slutligen genomförs parametriska studier för att undersöka påverkan av präglingsmönstergeometri på den mekaniska prestandan hos präglat mjukpapper. Efter att ha klarat verifierings- och valideringsstegen är modellen redo att fungera som ett lätthanterligt, mindre tidskrävande och mer kostnadseffektivt alternativ till experimentell testning för att studera präglingsprocessen. Det kan också användas som ett verktyg för att undersöka effekten av en eller flera modellparametrar på prägling genom att helt enkelt ändra dem och studera de nya resultaten.

This thesis is about the development of a new numerical method for the analysis of composite shells. The present work is based on Reissner Mixed Variational Theorem (RMVT), the Sublaminate Generalized Unified Formulation (S-GUF), and the Ritz approximation. The present work investigates a more efficient way to compute transverse stresses (sigma_xz, sigma_yz, sigma_zz) based upon RMVT, allowing assigning their order of continuity a priori. This is a great advantage compared to a conventional displacement-based approach. In order to enable computing of both global and local responses (depending on the user’sneeds) the S-GUF framework was adopted. The Generalized Unified Formulation (GUF) enables the implementation of approximations with virtually unlimited algebraic order within a single code, and the order could also vary for different variables. In addition to the GUF, the concept of Sublaminate was utilized, allowing for sub-sectioning of the domain in the thickness direction into sublaminates, and it is then possible to apply different formulations in each of these sub-domains. The curvature of the shells is strictly defined by their radius-to- thickness ratio. The flexibility of S-GUF is helpful in the sense that curvature is only introduced and treated if needed by the particular case at hand. The governing equations obtained applying S-GUF to RMVT were solved in a weak formulation using the Ritz approximation. This choice was made to save computational time, which is one of the main benefits of the presented method. Validation of the code was made by comparing results from the present formulation with solutions available in the literature. Good to excellent agreement was found for several benchmark cases, supporting that the formulation is valid and provides reliable solutions.Finally, numerical and analytical considerations about the developed method were made: its numerical stability, how to tune its parameters, and which models result more correct from an analytical standpoint. / Denna avhandling handlar om utvecklingen av en ny numerisk metod för analys av kompositskal.Det aktuella arbetet är baserat på Reissner Mixed Variational Theorem (RMVT), Sublaminate Generalized Unified Formulation (S-GUF) och Ritz-approximationen.Arbetet går ut på att ta fram ett mer effektivt sätt att beräkna spänningar ut ur planet (sigma_xz, sigma_yz, aigma_zz) och utnyttjar RMVT, vilket möjliggör lokal hantering av kontinuitet i varierande ordning, definierad a priori. Detta innebär en stor fördel jämfört med en konventionell förskjutningsbaserad metod. För att möjliggöra beräkning av både global och lokal lösning, beroende påanvändarens behov, antogs S-GUF-ramverket. Den generaliserade enhetliga formuleringen (GUF) gördet möjligt att inom samma formulering implementera approximationer med i princip obegränsad algebraisk ordning, vilka dåocksåkan skilja mellan olika variabler. Förutom GUF används även konceptet Sublaminate som gör det möjligt att dela upp domänen i tjockleksriktningen i underregioner (sublaminate), och det är dåmöjligt att tillämpa olika formuleringar i var och en av dessa subdomäner. Krökningen hos ett skal definiers strikt av förhållandet mellan dess radie och tjocklek. Flexibiliteten hos S-GUF är fördelaktig dåkrökning endast hanteras för de specifika fall där det förekommer. De ekvationer som erhålls genom att applicera S-GUF på RMVT löses påsvag formmed användning av Ritz approximation. Detta val gjordes för att möjliggöra en snabbare beräkningstid, vilket är en av fördelarna med denna metod. Genom att jämföra de resultat med lösningar tillgängliga i litteraturen var det möjligt att validera resultaten och därmed även själva formuleringen. God till utmärkt överensstämmelse påvisades för ett antal olika standardfall vilket styrker att metoden fungerar och attdess lösningar är pålitliga. Slutligen ritades numeriska och analytiska överväganden om metoden här utvecklad, såsom dess numeriska stabilitet, hur man ställer in dess parametrar och vilka modeller somär mer korrekta ur en analytisk synvinkel.

Employing the Finite Element Method (FEM), we numerically study three problems involving free and forced vibrations of linearly and nonlinearly elastic plates with a third order shear and normal deformable theory (TSNDT) and the three dimensional (3D) elasticity theory. We used the commercial software ABAQUS for analyzing 3D deformations, and an in-house developed and verified software for solving the plate theory equations. In the first problem, we consider trapezoidal load-time pulses with linearly increasing and affinely decreasing loads of total durations equal to integer multiples of the time period of the first bending mode of vibration of a plate. For arbitrary spatial distributions of loads applied to monolithic and laminated orthotropic plates, we show that plates' vibrations become miniscule after the load is removed. We call this phenomenon as vibration attenuation. It is independent of the dwell time during which the load is a constant. We hypothesize that plates exhibit this phenomenon because nearly all of plate's strain energy is due to deformations corresponding to the fundamental bending mode of vibration. Thus taking the 1st bending mode shape of the plate vibration as the basis function, we reduce the problem to that of solving a single second-order ordinary differential equation. We show that this reduced-order model gives excellent results for monolithic and composite plates subjected to different loads. Rectangular plates studied in the 2nd problem have points on either one or two normals to their midsurface constrained from translating in all three directions. We find that deformations corresponding to several modes of vibration are annulled in a region of the plate divided by a plane through the constraining points; this phenomenon is termed mode localization. New results include: (i) the localization of both in-plane and out-of-plane modes of vibration, (ii) increase in the mode localization intensity with an increase in the length/width ratio of a rectangular plate, (iii) change in the mode localization characteristics with the fiber orientation angle in unidirectional fiber- reinforced laminae, (iv) mode localization due to points on two normals constrained, and (iv) the exchange of energy during forced harmonic vibrations between two regions separated by the line of nearly stationary points that results in a beating-like phenomenon in a sub-region of the plate. This technique can help design a structure with vibrations limited to its small sub-region, and harvesting energy of vibrations of the sub-region. In the third problem, we study finite transient deformations of rectangular plates using the TSNDT. The mathematical model includes all geometric and material nonlinearities. We compare the results of linear and nonlinear TSNDT FEM with the corresponding 3D FEM results from ABAQUS and note that the TSNDT is capable of predicting reasonably accurate results of displacements and in-plane stresses. However, the errors in computing transverse stresses are larger and the use of a two point stress recovery scheme improves their accuracy. We delineate the effects of nonlinearities by comparing results from the linear and the nonlinear theories. We observe that the linear theory over-predicts the deformations of a plate as compared to those obtained with the inclusion of geometric and material nonlinearities. We hypothesize that this is an effect of stiffening of the material due to the nonlinearity, analogous to the strain hardening phenomenon in plasticity. Based on this observation, we propose that the consideration of nonlinearities is essential in modeling plates undergoing large deformations as linear model over-predicts the deformation resulting in conservative design criteria. We also notice that unlike linear elastic plate bending, the neutral surface of a nonlinearly elastic bending plate, defined as the plane unstretched after the deformation, does not coincide with the mid-surface of the plate. Due to this effect, use of nonlinear models may be of useful in design of sandwich structures where a soft core near the mid-surface will be subjected to large in-plane stresses. / Doctor of Philosophy / Plates and shells are defined as structures which have thickness much smaller as compared to their length and width. These structures are extensively used in many fields of engineering such as, designing ship hulls, airplane wings and fuselage, bodies of automobile, etc. Depending on the complexity of a plate/shell deformation problem, deriving analytical solutions is not always viable and one relies on computational methods to obtain numerical solutions of the problem. However, obtaining 3-dimensional (3D) numerical solutions of deforming plates/shells often require high computational effort. To avoid this, plate/shell theories are used for modeling these structures, which, based on certain assumptions, reduce the 3D problem into an equivalent 2-dimensional (2D) problem. However, quality of the solution obtained from such a theory depends on how suitable the assumptions are for the specific problem being studied. In this work, one such plate theory called as the Third Order Shear and Normal Deformable Theory (TSNDT) is used to model the mechanics of deforming rectangular plates under different boundary conditions (constraint conditions for the boundaries of the plate) and loading conditions (conditions of applied loads on the plate). We develop the TSNDT mathematical model of plate deformations and solve it using a computational technique called as the Finite Element Method (FEM) to analyze three different problems of mechanics of rectangular plates. These problems are briefly described below. vi In the first problem, we study vibrations of rectangular plates under time dependent (dynamic) loads. When a dynamic load acts on a plate, due to the effects of inertia, the plate continues to vibrate after the removal of the load. This is analogous to ringing of a bell long after the strike of the hammer on the bell. In this study we show that such vibrations of a rectangular plate can be varied by changing time dependencies of the applied load. We observe that under certain particular loading conditions, vibrations of the plate becomes miniscule after the load removal. We call this phenomenon as Vibration Attenuation and investigate this computationally in different problems of plate deformation using FEM solutions. In the second problem, we computationally investigate the effects of presence of internal fixed points (points within the volume of the plate restricted of motion) on the vibration characteristics of rectangular plate using TSNDT FEM solutions. We observe that when one or more points at locations inside a rectangular plate are fixed, vibration behavior of the plate significantly changes and the deformations are localized in certain regions of the plate. This phenomenon is called as Mode Localization. We study mode localization in rectangular plates under different boundary and loading conditions and analyze the effects of plate dimensions, locations of the internal fixed points and dynamic load characteristics on mode localization. In the third problem, we investigate the effects of introduction of nonlinearities into the TSNDT mathematical model of plate deformations. Simple models in mechanics consider materials to be linearly elastic, which means that the deformations of a body are proportional to the applied loads in a linear relation. However, most materials in nature undergoing large deformations (human tissues, rubbers, and polymers, for example) do not behave in this fashion and their deformation depends nonlinearly to applied loads. To investigate the effects of such nonlinearities, we study the behavior of nonlinearly elastic plates under different boundary and loading conditions and delineate the differences in the results of linearly elastic and nonlinearly elastic plates using the TSNDT FEM solutions. Findings of this study establishes that linear models overestimate the plate deformation under given boundary and loading conditions as compared to nonlinear models. This understanding may help in developing better design criteria for plates undergoing large deformations.

Detta projekt var ett samarbete mellan Luleå tekniska universtiet och CranabSlagkraft och har behandlat ett förbättringsprojekt av befintliga inner- och yttergripklor med namnet E36 tillhörande skogsgrip CE360. Produkten hade en dåvarande konstruktionslösning som företaget länge inte har varit nöjd med. Klorna hade plåtar som svetsades fast på sidan av gripklorna för att skapa stabilitet. Utan dem skulle gripen inte ha tillräcklig hållfasthet då klorna skulle böjas och deformeras omgående vid användning. Sedan hade gripen även problem med stora nötningsproblem. Denna grip ville företaget förbättra då den var både ekonomisk kostsam och tidskrävande att bygga. Produkten var inte heller ekonomisk gynnsam för slutanvändarna då produkten hade så kort teknisk livslängd. Detta projekt har bearbetat dessa problem noggrant med grundlig analys på ett ingenjörsmässigt sätt som resulterat i en slutgiltig lösning med ett ritningsunderlag som har presenterats godkänts och byggdes till en prototyp under 2012. / This project was a collaboration between Luleå University of Technology and CranabSlagkraft and has addressed an improvement project of existing inner and outer gripc laws named E36 belonging to the forestry grip CE360. The product had a previous design solution that the company had long been dissatisfied with. The claws had plates welded to the sides of the grip claws to create stability. Without them, the grip would not have sufficient strength as the claws would bend and deform immediately during use. Furthermore, the grip also had significant wear issues. The company wanted to improve this grip as it was both economically costly and time-consuming to build. The product was also not economically beneficial for end-users as it had such a short technical lifespan. This project has meticulously addressed these problems with thorough analysis in an engineering manner, resulting in a final solution with a drawing basis that has been presented, approved, and built into a prototype in 2012.

The exploration of Microelectromechanical systems (MEMS) represents a crucial aspect in the advancement of modern science and technology. They offer low-cost solutions to miniaturize numerous devices. The increasing use of MEMS applications in biological research has created a pressing need for reliable micromanipulation tools. In this context, microgrippers have emerged as promising tools for the precise handling and characterization of biological samples. This thesis presents a novel biocompatible microgripper that utilizes electrothermal actuation integrated with a rotary capacitive position sensor. To overcome the limited displacement possibilities associated with electrothermal actuators, this microgripper incorporates conjugate surface flexure hinges (CSFH). These hinges enhance the desired tweezers output displacement. The designed microgripper can in principle manipulate biological samples ranging in size from 15 to 120 μm. Based on the sensitivity calculation of the rotary capacitive position sensors, the sensitivity of the displacement measurement is 102 fF/μm. By employing a kinematics modeling approach based on the pseudo-rigid-body method (PRBM), an equation for the displacement amplification factor is developed, and this equation is subsequently verified through FEM-based simulations. By comparing the amplification ratio value obtained from the analytical modeling and simulations, there is an excellent match, with a relative difference of only ~1%, thus demonstrating the effectiveness of the PRBM approach in modeling the kinematics of the structure under investigation. In addition to this, by using analytical modeling based on finite elements method (FEM), the design of the electrothermal actuator and the heat dissipation mechanism is optimized. FEM-based simulations are used to validate the theoretical modeling, demonstrating good agreement between the displacements derived from analytical modeling and simulations. The temperature difference (∆T) across a range from room temperature to 278°C exhibits a relative difference of ~2.8%. Moreover, underpass technology is implemented to ensure that electrical signals or disturbances from other parts of the device, such as the electrothermal actuation system, do not interfere with the operation and integrity of the gripping mechanism. Ultimately, the microgripper is fabricated using conventional MEMS technology from a silicon-on-insulator (SOI) wafer through the deep reactive ion etching (DRIE) technique. The integration of theoretical modeling, simulations, and practical fabrication highlights a compelling approach that has the potential for transformative applications in the field of micromanipulation and biological sample handling. Furthermore, we propose a C-shaped structure with a curved beam mechanism to improve the movement provided by the thermal actuators. The design of experiment (DOE) method is used to optimize the geometrical parameters of our proposed device. Analytical modeling based on Castigliano's second theorem and finite element method (FEM) simulations are used to predict the behavior of the symmetrical C-shaped structure; the results are in good agreement. The MEMS-based rotational structures are fabricated on silicon-on-insulator (SOI) wafers using bulk micromachining and deep reactive ion etching (DRIE). The fabricated devices are tested; our findings reveal that our proposed MEMS rotational structure outperforms the symmetrical lancet structure by 28% in terms of delivered displacement. Furthermore, the experimental results agree well with those obtained through numerical analysis.

A dynamic simulation of the response of an inflatable dam subjected to a flood was carried out to determine the survivability envelope of the dam where it can operate without rupture, or overflow. A fully nonlinear free-surface flow was applied in two dimensions using a mixed Eulerian-Lagrangian formulation. An ABAQUS finite element model was used to determine the dynamic structural response of the dam. The problem was solved in the time domain which allows the prediction of a number of transient phenomena such as the generation of upstream advancing waves, and dynamic structural collapse. Stresses in the dam material were monitored to determine when rupture occurs. An iterative study was performed to find the service envelope of the dam in terms of the internal pressure and the flood Froude number for two flood depths. It was found that the driving parameter governing failure of the dam was the internal pressure. If this pressure is too low, the dam overflows; if this pressure is too high, the dam ruptures. The fully nonlinear free-surface flow over a semi-circular bottom obstruction was studied numerically in two dimensions using a similar solution formulation as that used in the previous study. A parametric study was performed for a range of values of the depth-based Froude number up to 2.5 and non-dimensional obstacle heights up to 0.9. When wave breaking does not occur, three distinct flow regimes were identified: subcritical, transcritical and supercritical. When breaking occurs it may be of any type: spilling, plunging or surging. In addition, for values of the Froude number close to 1, the upstream solitary waves break. A systematic study was undertaken, to define the boundaries of each type of breaking and non-breaking pattern, and to determine the drag and lift coefficients, free surface profile characteristics and transient behavior. / Master of Science

Vatteninträngning är en viktig faktor som måste tas i beaktande vid konstruktion av komponenter som avses användas i krävande miljöer. Testning av vatteninträngning kan ske genom nedsänkning i en öppen vattenbehållare till önskat djup, men även genom ett simuleratvattendjup i en vattenfylld behållare som trycksätts. I följande arbete testas ett grundkoncept för konstruktion av en trycktank för IP-testnig av klasserna IPx7 samt IPx8, vilketinnebär att den utsätts för förhållandevis låga tryck. Grundkonceptet testas för att identifiera dess brister och förbättringar föreslås. Alternativa lösningar för konstruktionen testassedan och jämförs med grundkonceptet. Analysen av konstruktionerna bygger i huvudsakpå finita emementanalyser, men har även inslag av mekanikberäkningar. Resultatet visaratt en trycktank med rätblocksform kan vara en möjlig konstruktion om hörnförstyvningaranvänds, samt dess infästnigspunkter placeras in från trycktankens kanter. En cylindriskform på trycktank är dock att föredra framför en i formen av ett rätblock. Det visar ävenatt halvsfäriska ändar på trycktanken är att föredra jämfört med plana. Resultatet visaräven att en trycktank tillverkad i låglegerat stål är att föredra ur konstruktionssynpunkt,jämfört med en tillverkad i polymera material. Fortsatta arbeten krävs dock för analys avcylindriska trycktankar i stål med sfäriska ändar. / Water ingress is an important factor that should be considered when designing componentsintended for use in harsh environments. Water ingress can be tested by immersion to thedesired depth in an open water container, an alternative to this method is simulatingthe water depth in a pressurized water-filled container. In this study, a basic concept forthe construction of a pressure tank for IP testing of class IPx7 and IPx8 is examined,which means that it is exposed to relatively low pressures. The basic concept is examinedto identify its shortcomings and improvements are suggested. Alternative solutions forthe construction of a pressure tank are then investigated and compared with the basicconcept. The analysis of the constructions is mainly based on finite element analyses, butalso has elements of classical mechanics equations. This study shows that a pressure tankwith a shape like a cuboid could possibly be constructed if corner braces are used and itsattachment points are placed away from the edges of the pressure tank. This study showsthat a pressure tank in a cylindrical shape is preferable to one in a cuboid shape and thathemispherical pressure tank heads are preferable to flat ones. The study also shows thata pressure tank made from low-alloy steel is preferable from a construction standpoint,compared to one made of polymeric materials. However, further studies are required forthe analysis of cylindrical steel pressure tanks with hemispherical heads.

Miniskruvar används ofta inom tandreglering för att fästa anordningar för justering av tänder. Ibland går skruvarna sönder under insättning. Syftet med detta arbete är att ta reda på varför skruvarna går sönder.  Denna tekniska rapport undersöker hållfasthetsegenskaperna hos dessa miniskruvar. Testning på skruvarna utförs för att undersöka deras känslighet i olika belastningsfall och en enkel analys utförs med hjälp av linjärt elastiska materialegenskaper och FEM-beräkningar i Ansys. Undersökningen finner att skruvarnas känslighet för vridmoment är högre då det kombineras med andra belastningar och att en rak inskruvning är att föredra.