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512 Uppsatser om Isometric strength - Sida 9 av 35

Optimering av sintrade kugghjul

Powder Metal (PM) gears are machine element components which operate under the same principle as conventional gears, but, due to their intrinsic material characteristic need to be designed slightly different, and its manufacturing process offers advantages previously unobtainable by conventional steel gear manufacturing methods. The use of PM in similar applications, such as synchronous hubs, makes them a suitable candidate for production in such material. The current master thesis work focuses on gear design using PM by utilizing finite element method (FEM) to reduce weight and inertia taking into account root bending strength and tooth deflection.First a topological optimization is used to determine feasible candidates for different web designs which have as objective to reduce volume, similar topologies were shown during different loading conditions; and hence, this topology was chosen as a suitable candidate. A shape optimization of the topological candidate was performed having as state variables root bending strength, independent for compressive and tensile side of the tooth loading; and tooth deflection, which in concept can be correlated to static transmission error (TE).Another aspect in this thesis analysed is the possibility to incorporate non-trochoid root geometry, a trochoid root is always present when machining with a hob, into the gear root and hence reduce the stress concentration here. Due to the use of PM, a non-symmetric optimized root can be achieved and hence be optimizing compression and tension.Results showed significantly lower inertia, for example certain results showed 40% reduced when compared to solid gear, with adverse effects as increase in tooth deformation and increase in maximum principal stress.

Stamskador i gallringsbestånd

This study was conducted on a property with a thinning machine team. The purpose was to investigate in which machine, the harvester or the forwarder, that caused most damage to the trees in six different stands. Different factors, related to the damage frequency in the stands, were checked out. For example: basal area per hectare, thinning strength, tree diameter and the rate of production. The harvester drivers were also interviewed about how, when and why stem damages occur and how to minimize them. The study stated that 4.3 percent of the trees were damaged. Out of these 88 percent was caused by the harvester and the rest, 12 percent, by the forwarder..

Fågel fisk eller mittemellan?

The project is a thesis which intends to strengthen the form language and increase the user friendliness of an International Moth. This is a single handed dinghy with only one sail. It sails on two hydrofoils and receives a very high speed compared to its size, and are therefore often referred to as ?the Formula One on water ?. The result is a new concept where the aerodynamic forces have been used to stabilize the boat and relieve the hydrofoils.

Högtrycket-Initierande undersökning av nytt limträmaterial

The present study examines a new production line of glue-laminated wood (glulam). The glulam is produced from non-planed boards of spruce, which also is convex, that is pressed together with high pressure during the gluing. According to a economic calculation, the material has a economical potential mainly on account of the absent planning. The study mainly found out that the shear strength of the material tolerated the demanded values in standard SS-EN 386, but the delaminating values did not. Since there are more areas to be studied around the material, the prospect to achieve the right delamination values is seen as positive..

Behandlingsmetoder vid iliotibialt friktionssyndrom: En litteraturstudie

Iliotibialt friktions syndrom (ITFS) är en av de vanligaste överbelastningsskadorna som drabbar knäet. Traditionellt har skadan betraktats som ett friktionssyndrom, senare studier har dock hävdat att en kompression av underliggande fettvävnad är orsaken till diagnosen. Etiologin och patologin bakom diagnosen har därmed inte kunnat fastställas. Kliniskt tillämpas stretching, styrketräning av höftabuktorer, neuromuskulär korrigering och myofaschiella behandlingsmetoder i rehabiliteringen av ITFS. Syftet med denna litteraturstudie var att sammanställa det vetenskapliga underlaget för behandlingsmetoder vid iliotibialt friktions syndrom.

Konstruktion av statorstomme för synkrongenerator : Förslag på design av statorstomme för användning i vertikalaxlade vindkraftverk

This thesis describes a conceptual design of a support frame for a synchronousgenerator used in a vertical axis wind power plant. In this system the generator isplaced on ground level. The thesis also considers the design of housing for thesupport frame and generator. The concept presented in this report is based on anearlier design. Besides geometric design, simplified simulations has been run in orderto optimize some of the parts included in the construction considering naturalfrequencies and structural strength.The result is presented as CAD-models andan assembly drawing..

Utvärdering av infästningar i sandwichkonstruktioner för fordonsapplikationer

The automotive industry is increasingly studying lightweight solution in their designs, also rational production and low costs in materials and manufacturing methods are of great interest. This thesis consisted in the practical evaluation of anchors for sandwich panels. The object was to study loads of shearing and pull out of the plane. The experiments were carried out on panels made up of 1mm aluminium coatings and 50mm extruded polystyrene (XPS) at its core. As the fasteners used simple methods such as blind rivets, screw and glue.

Punktlasttestning av olika bergartstyper i Kiirunavaaras liggvägg

Examensarbetet ingår i den slutliga delen av kandidatutbildningen i naturresursteknik och utgör 15 högskolepoäng. Utbildningen är inriktad mot geologi och det avslutande arbetet ska ha anknytning till ämnet. Under våren 2012 presenterade representanter för LKAB förslaget att basera examensarbetet på att dokumentera hållfastheten hos bergarter från Kiirunavaaras liggvägg med hjälp av punktlasttestning. Tidigare undersökningar av hållfastheten hos bergarterna i Kiirunavaara har främst gjorts genom enaxiella tryckhållfasthetsmätningar. Det finns ett behov av att undersöka hållfastheten hos bergarterna i Kiirunavaara då gruvbrytningen sker djupare ned i jordskorpan och kraven på säkerheten ständigt ökar.

Lyftanordning för kraftuttag

This thesis has been developed inassociation with Strängbetong AB, Sweden.A few years backCementa AB introduced a new type of cement on the Swedish market: Byggcement,which is a Portland Limestone Cement. This type of cement is better for theenvironment and cheaper than Rapid Hardening Cement which is used today at SträngbetongAB.Strängbetong AB isvery interested in a change of cement in the factory and wants to know what ittakes to make a transition from Rapid Hardening Cement to Byggcement.This final projectaims at investigating how the workability and strength development are affectedby a transition from the existing cement to Byggcement and how we can change theproperties of the concrete by adding different types of superplasticizers. Laboratory and factoryexperiments were made, to investigate the transition..

El Niño Southern Oscillation och dess atmosfäriska fjärrpåverkan.

This paper is a literature study aiming to describe scientists newest theories andknowledge concerning the El Niño and Southern Oscillation. Firstly I have described the?normal? conditions with rising and sinking air in Hadley- and Walker-cells in theequatorial Pacific and from there moved on to explaining the reversed circulation patternsand higher sea surface temperatures (SST) leading to rising air and anomalousprecipitation in eastern Pacific constituting the El Niño phenomenon. My outermostinterest regarding El Niño has been the associated teleconnections, especially in nontropicalareas. I have described the El Niño effect on the Indian summer monsoon, ontropical cyclones and on storms and precipitation on higher latitudes.

Optimering av betong med Byggcement (CEM II) till håldäcksproduktion

This thesis has been developed inassociation with Strängbetong AB, Sweden.A few years backCementa AB introduced a new type of cement on the Swedish market: Byggcement,which is a Portland Limestone Cement. This type of cement is better for theenvironment and cheaper than Rapid Hardening Cement which is used today at SträngbetongAB.Strängbetong AB isvery interested in a change of cement in the factory and wants to know what ittakes to make a transition from Rapid Hardening Cement to Byggcement.This final projectaims at investigating how the workability and strength development are affectedby a transition from the existing cement to Byggcement and how we can change theproperties of the concrete by adding different types of superplasticizers. Laboratory and factoryexperiments were made, to investigate the transition..

Kroppsuppfattning hos värnpliktiga män

Body awareness is a term that refers to a person´s perception and knowledge about his or her body. It includes proportion, size, weight, contour and image of ones body. The Ben- Tovim Walker Body Attitudes Questionnaire (BAQ) contains 44 questions concerning the different aspects of body awareness: Feeling fat, Body disparagement, Strength and fitness, Salience of weight, Attractiveness and Lower body fatness. The purpose of this study was to investigate body awareness among men in military recruit training. BAQ was distributed to fifty recruits for military service in Boden.

Kan probiotika förebygga atopiskt eksem hos högriskbarn?

Sahlgrenska Academy at University of Gothenburg Department of Internal Medicine and Clinical NutritionAbstractTitle: Can probiotics prevent atopic dermatitis in children with high risk?Author: Laura Pienihäkkinen and Max OlinSupervisor: Heléne Bertéus ForslundExaminer: Anna WinkvistProgramme: Dietician study programme, 180/240 ECTSType of paper: Examination paper, 15 hpDate: May 22, 2012Background Allergic disease is today common, this including atopic dermatitis, which is the most common inflammatory skin disease in the world. Heredity has been shown to play a major role in the development of this disease. It is therefore of high interest for both the individual and society to find effective methods for preventing atopic dermatitis in individuals with high risk profile. Probiotics are beneficial for the bacterial profile in the intestine and it is therefore of interest to study if they through their anti-inflammatory effect could prevent atopic dermatitis.Objective The aim was to study whether administration of probiotics to the mother and the child (directly or via breast milk) could prevent atopic dermatitis in children with high risk profile (at least one first degree relative with a diagnosed allergic disease).Search strategy A systematic literature search was done in databases PubMed and Scopus with search terms maternal, prenatal, probiotics, allergy, atopic dermatitis, prevention, and children.Selection criteria Randomized, controlled human studies and original articles in English were included.

Effekten av frukostens glykemiska index på energiintag hos barn och ungdomar

Sahlgrenska Academyat University of GothenburgDepartment of Internal Medicine and Clinical NutritionTitle: The effect of the glycemic index of breakfasts in energy intake inchildren and adolescentsAuthor: Charlotte Olofsson, Cornelia Johansson and Maria NordbeckSupervisor: Fredrik BertzExaminer: Ingrid LarssonProgramme: Dietician study programme, 180/240 ECTSType of paper: Examination paper, 15 hpDate: May 16, 2013Background: The glycemic index (GI) and it´s effect on energy intake is a debated subject.Research has been done whether food with lower GI decreases hunger and lowers energyintake, which could be an effective tool to prevent overweight in children and adolescents.Breakfast eating is successful for maintaining a healthy weight and it´s therefore interesting tosee if the quality of the carbohydrates matters.Objective: To evaluate the scientific evidence regarding the effect of GI of breakfasts inchildren?s and adolescents energy intake.Search strategy: To find relevant articles, a systematic literature search was made in thedatabases PubMed, Scopus and Cochrane. Search terms that were used were: breakfast,breakfast quality, children, glycemic index, energy intake, obesity.Selection criteria: Randomized controlled trials and cohort trials, breakfast eatingindividuals, children and adolescents under 18 years old, reported glycemic index. Outcomemeasurements: Energy intake.Data collection and analysis: Six original articles met the inclusion criteria and werereviewed by the SBU audit template for randomized and controlled studies. There after onearticle was excluded because of very low quality of the study.

Konstruktion av specialmaskin för orientering och positionering av nyckelämnen

The thesis in product development ? mechanical design includes 15 credits and was carried out during the spring of 2014 at Semcon in Eskilstuna. The task is to construct a special machine for positioning and orientation of a key blank found in six different shapes, the construction is a part of a larger machine for encoding the key blank where a pick- and-place device or robot pick up the key blank and deliver it further in the process. The entire construction is designed for ASSA OEM Gothenburg.In order to accomplish the project the first step was to analyze the existing solutions to similar problems on the market in a current situation analysis to create an understanding of the problem. This was followed by a flow analysis and a functional analysis to get a deeper understanding of the problem and structuring the machine's process flow and its features.

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