The demands for an increase in productivity and reduced assembly costs require engineers to automate solutions that replace manual labor. This work concentrated on a common assembly primitive, threaded fastener insertion, in an effort to determine the nature of contact between a bolt and nut during thread mating. The assembly problem was initially simplified as a two-dimensional analysis to gain an understanding about how contacts between the bolt and nut change during counter-clockwise motion. Tessellated solid models were used during three-dimensional collision analysis in such a way that the approximate location of the contact point was enumerated. The advent of a second contact point presented a more constrained contact state since we are interested in maintaining both contacts; thus the bolt rotated about a vector defined by the initial two contact points until a third contact location was found. By analyzing the depth of intersection of the bolt into the nut as well as the vertical movement of the origin of the bolt reference frame, we determined that there are three types of contacts states present: unstable two-point, quasi-stable two-point, stable three point. Though the unstable case remains to be deciphered, the parametric equations derived in this work can be used without modification to create a full spectrum of maps at any point in the history of a threaded assembly problem. We investigated 81 potential orientations, each of which has its own set of contact points. From this exhaustive examination, we are capable of detailing a contact state history and, from this, have the potential to develop a constraint network. / Master of Science

In this project, the main research objective is intend to seek criteria for evaluating the capacity of BAC screw fasteners with mixed configuration of waterproof seal washer, sealer tape and different pre-drill holes to determine shear and tension strength values for the screws used in cold-formed steel connections. The thesis presents the design methods and test program conducted to investigate the behavior and strength of the screw connections in shear and tension test. Test results were compared with AISI design provisions to determine if new design equations will be developed for those screws used in BAC cooling tower applications. LRFD resistance factors and ASD safety factors were investigated to the proposed design equations.

No description available.

This thesis examines the bearing capacity, stiffness, shear and moment force of a continuous wooden beam and how the parameters of the beam changes when the beam is spliced ​​with nail plate. A literature study has been conducted to examine which studies have been carried out in this field. Construction timber is the most common wooden element for wooden constructions but has limitations in available lengths since the maximum length manufactured is 5400 mm. If larger lengths are required, splicing must occur or use of other materials.   The study examines a 2 series, a 3-point series (moment and shear) and a 4-point series (moment). Each series consists off 3 trials in each series to see how shear and moment force affect the strength. The study also shows which off the joints that gives the least strength. The samples are tested in a draw and pressure machine lying on 2 supports and with a point load for the 3-point method and 2-point loads for the 4-point method. In the trials pressure is applied until the beams break. The study investigates the lab results, fracture state and use state for the wooden beams being tested. The result of the study shows that a splicing will lower the wood's carrying capacity between 21-60% compared to a non-spliced beam for the 3-point method and a reduction of 40-66% compared to a non-spliced beam for the 4-point method. Despite the lowered bearing capacity all the experiments are still within the characteristic value and approved for use. A larger dimension on the nail plate would probably have given a better value. / Detta examensarbete undersöker bärförmåga, styvhet, moment- och tvärkrafts påverkan hos en kontinuerlig träbalk och hur parametrarna för balken ändras då balken skarvas med spikplåt. En litteraturstudie har genomförts för att undersöka vilka studier som utförts på området. Konstruktionsvirke är det vanligaste träelementet vid träkonstruktioner men har begränsningar i tillgängliga längder då maxlängden som tillverkas är 5400mm. Vid behov av större längder måste skarvning förekomma eller användning av andra material. I studien undersöks två serier, en 3-punktsserie (moment och tvärkraft) samt en 4-punktsserie (moment). Varje serie består av 3 försök för att se hur moment och tvärkraft påverkar hållfastheten. Studien visar även vilken typ av skarv som ger minst hållfasthet. Proverna testas i en drag-tryck-maskin liggandes på 2 upplag med 1 punktlast anbringad för 3-punktsmetoden och 2 punktlaster för 4-punktsmetoden. I försöken anbringas kraft på balkarna tills de går i brott. Studien undersöker labbvärdet, brottstadiet och bruksstadiet för balkarna som testas. Analysen av försöken visar att en skarvning kommer sänka balken bärförmåga med mellan 21–60% gentemot en ren träbalk för trepunktsmetoden och en minskning på mellan 40–66% gentemot en ren träbalk för fyrpunktsmetoden. Trots den sänkta bärförmågan för balken i testerna är alla försöken inom det karaktäristiska värdet och godkända att användas. En större dimension på spikplåten hade antagligen gett ett bättre värde.

Abstract The economic growth of Taiwan was guided by small and medium enterprises; Especially Taiwan fastener industry acts an important role for Taiwan small and medium enterprises. As an old saying goes ¡§the young soldier sets up the great merit. ¡§ This is best way to describe Taiwan fastener industry. Taiwan fastener industry is playing an important part of National Development, but even government rulers ignore this. Unless you are part of Taiwan fastener industry, you can not understand that this industry is such respectable. It has been more 60 years since Taiwan launched into its name of fastener supply center. Mostly Taiwan fastener industry is small and medium enterprises. However these enterprises could not get much help from government or each other. They all fight alone. Many companies cannot survive when they meet difficulties and bottlenecks. Even companies want to help each other, integration are a big problem to them. This research is tried to discuss how Taiwan fastener industry to face China¡¦s Lower price competitive stratagem does. Author will all around discuss, analyzes and compare this topic¡§The strategic alliance will be applied between some companies of the fastener industry¡¨ to give to Taiwan fastener industry an all around competitive stratagem. Postgraduate student are working on this research not only to help running my own company but also as a Reference for Taiwan fastener industry.

Les assemblages à base de fixations montées avec interférence et prétension sont largement utilisés dans le domaine de la construction aéronautique, notamment dans les zones structurales fortement chargées et soumises à des sollicitations de fatigue. Les performances de ces assemblages sont sensibles à de nombreux paramètres liés à la géométrie et aux matériaux mis en jeu. Pour optimiser la qualité de ces liaisons et atteindre les gains de durée de vie attendus, il est important de disposer de modèles à la fois rapides et fiables qui permettent, dès la phase de conception, d’évaluer l’influence des paramètres d’entrée sur les efforts caractéristiques de l’assemblage. Les travaux s’attachent, dans un premier temps, en s’appuyant sur une modélisation par éléments finis très détaillée du processus d’assemblage, à bien identifier les phénomènes mécaniques les plus caractéristiques des liaisons étudiées. Une approche analytique de premier niveau est ensuite développée. Elle conduit à un modèle d’estimation des efforts et de contraintes présentes dans les pièces assemblées qui produit des résultats très voisins de ceux obtenus avec le modèle de référence. Un modèle numérique dédié,basé sur des éléments finis axisymétriques et codé sous Matlab, est ensuite proposé. Il est apte à évaluer l’influence des variations des paramètres le long de l’interface entre les pièces tout en considérant les effets de bords. Une étude expérimentale basée sur une instrumentation de l’assemblage avec des fibres optiques à réseaux de Bragg est présentée. Les corrélations entre les résultats expérimentaux et ceux issus des modélisations sont très satisfaisantes / Assemblies based on interference fit fastener and preload are widely used in the fieldof aircraft construction, especially on structures heavily loaded and subjected to fatigue stresses.The performances of these assemblies are sensitive to many parameters related to the geometry and to the constitutive materials. To improve the quality of these assemblies and achieve the assembled parts. This simple model produces results very similar to those obtained with thereference model. A dedicated numerical model, based on axisymmetric finite elements and developed using Matlab code, is also proposed. It is able to evaluate the influence of parameter variations along the interface between the parts while considering the side effects. An experimental study based on an assembly instrumented with Fiber Bragg Gratings is presented.The correlations between the experimental results and those from the models are very satisfactory lifetime gains expected, it is important to use, from the early design phase, fast and reliable models in order to evaluate the influence of input parameters on the most significant efforts that take place around the fastener. In a preliminary phase, the work focuses on clearly identifyingthe mechanical phenomena characterizing the behavior of the mechanical connections understudy, using a very detailed finite element reference model of the assembly process. An analytical approach is then developed. It leads to a first level model for estimating loads and stresses in the assembled parts. This simple model produces results very similar to those obtained with the reference model. A dedicated numerical model, based on axisymmetric finite elements and developed using Matlab code, is also proposed. It is able to evaluate the influence of parameter variations along the interface between the parts while considering the side effects. An experimental study based on an assembly instrumented with Fiber Bragg Gratings is presented.The correlations between the experimental results and those from the models are very satisfactory

I den här rapporten har det studerats vilka fysikaliska parametrar som har direkt och indirekt påverkan vid frigörandet av huvor på ytterplagg för barn. Det har även studerats vilka av de parametrar som skulle kunna ingå i en testmetod. En standardiserad testmetod saknas idag och till följd av det kan inte huvor på barns ytterplagg ingå i en standard ur säkerhetsperspektiv. Saknaden av att ingå i en standard medför att många ytterplagg har huvor som är fastsydda och kan därför utgöra en stor fara om ett barn skulle fastna. Enligt Konsumentverket (2006) har flera dödsfall förekommit där barns ytterplagg har varit avgörande orsak, däribland huvor på barns ytterjackor när barn har fastnat i träd och lekredskap och inte kunnat ta sig loss. För att ta fram en testmetod behöver det fastställas vilka fysikaliska parametrar som har direkt påverkan vid frigörandet av huvor på ytterplagg som fastnar. I den här förstudien har observationer, beräkningar och tester i laboratorium samt undersökningar genomförts. Avgränsningar har gjorts i form av att undersöka endast ytterplagg som har huvor med fästanordning av tryckknappar i metall. De är vanligt förekommande på barns ytterplagg och testerna har visat på att de utgör en risk för barn då de fastnar utan ett ryck. Med det menas att om ett barn fastnar med sin huva exempelvis i början av en rutschbana och sakta glider nedåt, kommer det att ta lång tid innan kraften uppnår knapparnas öppningskraft. Tester på laboratorium med hjälp av dragprovning har visat att det kan gå upp mot 90 sekunder innan alla knappar öppnar sig om ett barn fastnar i sin huva. Det beror på att tryckknapparna hamnar i ett läge som gör att de måste öppnas i sidled, och det krävs mycket större kraft än om de öppnas i den vinkeln som de är tillverkade för att öppnas i. / In this thesis, the relevant physical parameters have been studied to determine if they are affected the release of hoods on children’s outerwear. It has been also studied which of these parameters could be included in a test method. A standardized test method does not exist today, therefore, the hoods of children's outerwears are not included in a standard from a safety perspective. As a result of it, there are still many outerwears for children that do not have detachable hoods, which can consequently cause danger when children get caught. According to the Swedish Consumer Agency (Konsumentverket 2006), several deaths have occurr- ed in which children's outerwears has been a determinant, including the situations when the hoods have been trapped in trees or play equipment and children could not escape. To be able to develop a test method, it is necessary to determine which physical parameters are affected when releasing of hoods on children's outerwears. This thesis is based on literature study, observations, calculations and experi- mental simulations in the laboratory. Only outerwears that have detachable hoods with metal fasteners have been selected to study as a demarcation of this project. The reason is that this kind of garments is very common among children, and this could lead to a risk for children when they get caught without a quick pull. It means when a child gets stuck with the hood in the beginning of a slide for example and continues to slide downwards slowly. Thus, it will take a long time before the snap fasteners can be opened by itself, in other words that the hood will be released from the garment. Experiments in the laboratory using tensile testing machine shows that it can take up to 90 seconds before all snap fasteners can be opened when a child becomes hanging. The reason could be that the lateral holding strength is much stronger than the snap action for a snap fastener. And it is not produced to be disengaging in this difficult way.

Cold-formed steel connections are commonly fastened using self-tapping self-drilling screws. The behavior of these connections can differ based on the screw manufacturer or the cold-formed steel product used, both of which have a large selection available for use in industry. Because of their popularity and the many possible variations of these connections, researchers have frequently tested screw connections to characterize their behavior. However, repeatedly conducting this type of experiment is time consuming and expensive. Therefore, the purpose of this work was to create finite element models that can successfully predict the behavior of single lap shear screw connections, a common connection type used in cold-formed steel framing. These models were created using the finite element program Abaqus/CAE. To validate these models, test results from Pham and Moen (2015) were used to compare the stiffness, strength, and failure mode of multiple connections. A parametric study is also conducted to determine the influence of contact parameters on the behavior of the model. The results showed that all models consistently had good agreement with the connection stiffness and that most of the models also had good agreement with the peak load and failure mode of the v tests. These results were also compared to the design equations available for screw connections from the American Iron and Steel Institute (AISI). This comparison revealed that the models are more successful at predicting screw connection behavior than AISI, and thus work is required to improve the accuracy of AISI’s design equations. The eventual goal of this work is to develop a procedure to build and validate models without requiring test data. This work continuing in the future can lead to recommendations to improve AISI’s design equations and to implement the behavior of the connections into large cold-formed steel framing models such as diaphragms or shear walls.

Mensfattigdom är ett problem som finns i hela världen där kvinnor inte har tillgång till ett säkert mensskydd och där tabun kring mens sitter hårt rotad. Detta bidrar till ökade ojämlikheter i världen. Denna kandidatuppsats beskriver en produktutvecklingsprocess av en återanvändningsbar binda. Syftet med denna studie är att ta fram en fungerande fästanordning samt utforska passformen för en existerande återanvändningsbar binda. Detta genom att använda tidigare forskning och genom marknadsundersökning. En uppdaterad binda och fästanordning tillverkas och analyseras för att kontrollera att den uppsydda protypen överensstämmer med de framtagna måtten. En avprovning sker där provpersonerna får utöva vissa rörelser och svara på en enkät angående komfort och passform av bindan och fästanordningen. Resultatet för avprovningen och enkäten ligger till grund för produktutvecklingen. Resultatet visar en vidareutveckling av passformen och en ny fästanordning. Studiens resultat visar också en ny kategorisering av återanvändningsbara bindor. Förhoppningen med denna studie är att bidra till en större förståelse av passform på bindor och att vidare forskning kan ske inom ämnet. / Menstrual poverty is an issue that exists all over the world where women do not have access to safe menstrual protection and where taboos around menstruation are deeply rooted. This adds to increased inequalities in the world. This bachelor thesis describes the product development process of a reusable menstrual pad. The purpose of this study is to develop a functional fastening device and improve the fit of an existing reusable pad. This is done by utilizing previous research and perform a market survey to develop an updated pad. The updated pad and fastener are manufactured and analysed to verify that the sewn prototype conforms to the dimensions established in the survey. The market survey includes a test where the test subjects carry out certain movements and answers a questionnaire regarding the comfort and fit of the bandage and the fastening device. The results of the survey and questionnaire then form the basis for product development. The result shows a further development of the fit and a new fastening device. The results of the study also show a new categorization of reusable sanitary pads. The hope with this study is to contribute to a greater understanding of the fit of sanitary pads and that further research can take place in the subject.

The development of structural monitoring systems is a critical research area because of the age and sustainment costs associated with many aircraft in use today. Specifically, integrated structural health monitoring (SHM) systems are advantageous because they allow for automated, near real-time assessment of the state of the structure, where the automation improves both the accuracy of the measurements and allows for more frequent system interrogation than possible with traditional nondestructive evaluation methods. Ultrasonic techniques are particularly well-suited for SHM systems because of their potential to detect and track damage well before structural failure using in situ sensors. The research problem considered in this thesis is detection and tracking of fatigue cracks emanating from fastener holes in metallic structural components. The sensing method utilizes attached ultrasonic transducers, and tracking of damage is achieved by employing a state estimation framework that incorporates a well-known empirical model for crack growth and a measurement model relating the ultrasonic response to crack size. The state estimation process is preceded by an automated crack detection algorithm, and can be followed by a prediction of remaining life assuming future usage. The state estimation framework provides a better estimate of crack size than either the ultrasonic measurement model or crack growth model alone. Although the example application is monitoring of fastener holes, the general approach is applicable to a variety of SHM problems.