This thesis deals with junction points of construction used in transport infrastructure, which are made of FRP composite material. Main focus is on bonded joints. The material and geometrical criteria od FRP material and there influence to junctions are analyzed. In sequential steps the development of the design of joints applicable to reference constructions - pedestrian walkways is documented. There are also presented practical experiences from the tests of joints of overlapped and single-sided joints, as well as experience from the design, production and testing of two types of pedestrian bridges on a real scale. Furthermore, extensive comparison of joints, in particular T-joints with closed profiles for selected types of fasteners, is provided. From a simple connection, screws and rivets or plain bonding to combined joints. These are assessed both in terms of bearing capacity and their deformation behavior. These tests are performed for two material combinations, FRP-FRP and FRP-steel.

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I Scanias elektriska och hybriddrivna fordon används elmotorer av typen P80 och P160. Båda motorer använder samma kontaktbrygga för elektrisk kontaktering mellan elmaskinen i motor-huset och växelriktaren. En tidigare utredning har kommit fram till att noggrannare analyser bör göras kring kontaktbryggans tillförlitlighet. I fokus står skruvförbanden som säkerställer kontakten mellan ingående kablar och elmotor. I det här arbetet görs teoretiska och empiriska undersökningar av de statiska förhållandena i dessa skruvförband och hur de påverkas av temperaturändringar. Undersökningen möjliggör tydliga slutsatser, och visar att temperaturvariation orsakar sättning och temporära förändringar av klämkraften. Förbanden är mycket känsliga för sättning och tem-peraturändringar. Det kan därför inte uteslutas att klämkrafterna i drift enligt kravspecifikation hamnar utanför gränserna av 1 till 10 kN. I ett sådant fall skulle kontaktbryggans strömöverförande funktion inte längre vara garanterad.Baserat på undersökningen tas fram sex alternativa koncept för kontaktbryggan. Två av dem är små förbättringar av den nuvarande lösningen, och fyra innebär nykonstruktioner med strömske-nor eller fjäderkontakter. Efter jämförelse av alternativen med den nuvarande lösningen rekom-menderas en nykonstruktion av kontaktbryggan med ingjutna strömskenor. Därutöver föreslås standardisering av materialegenskaper för koppar och mässing i skruvsammanhang. För en kort-siktig lösning bör mer väldefinierade åtdragningsmetoder komma till användning vid montering av skruvar på elkontakter. Detta kommer att minska klämkraftens spridning efter montering. / In Scania's electric and hybrid vehicles, P80 and P160 electric motors are used. Both motors use the same contact bridge for electrical connection between the electric machine in the engine housing and the inverter. A previous investigation has concluded that more accurate analyses should be made regarding the dependability of the contact bridge. The focus is on the screw connections that ensure the connection between the input cables and the electric motor. In this work, theoretical and empirical investigations of the static conditions in these screw connections are made and how they are affected by temperature changes. The examination allows clear conclusions, showing that temperature variation causes embedment and temporary changes in clamping force. The screw connections are very sensitive to embedment and temperature changes. Therefore, it cannot be precluded that the clamping forces end up outside the limits of 1 to 10 kN, when in operation according to the requirements specification. In such a case, the contact bridge's conducting function would no longer be guaranteed.Based on the examination, six alternative concepts for the contact bridge are presented. Two of them are small improvements to the current solution, and four involve new constructions with busbars or spring contacts. After comparing the alternatives with the current solution, a new construction of the connector bridge with overmolded busbars is recommended. In addition, the standardization of material properties for copper and brass in screw contexts is proposed. For a short-term solution, more well-defined tightening methods should be used when installing screws on electrical contacts. This is going to reduce the spread of clamping force after assembly.

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No description available.

No description available.

As a valuable asset in human augmentation and medical rehabilitation, exoskeletons have become a major area for research and development. They have shown themselves to be effective tools for training and rehabilitation of individuals suffering from limited mobility. However, most exoskeletons are not capable of balancing without the assistance of crutches from the user. Leveraging technology and techniques developed for force controlled humanoid robots, a project was undertaken to develop a fully self-balancing, compliant lower-body robotic exoskeleton. Due to their many beneficial features, series elastic actuators were utilized to power the joints on the exoskeleton. This thesis details the development of four linear series elastic actuators (LSEA) as part of this project. All 12-degrees of freedom will be powered by one of these four LSEA's. Actuator requirements were developed by examining human gait data and three robot-walking simulations. These four walking scenarios were synthesized into one set of power requirements for actuator development. Using these requirements, analytical models were developed to perform component trade studies and predict the performance of the actuator. These actuators utilize high-efficacy components, parallel electric motors, and liquid cooling to attain high power-to-weight ratios, while maintaining a small lightweight design. These analyses and trade studies have resulted in the design of a dual-motor liquid-cooled actuator capable of producing a peak force 8500N with a maximum travel speed of 0.267m/s, and three different single-motor actuators capable of producing forces up to 2450N continuously, with a maximum travel speeds up to 0.767m/s. / Master of Science

L'accroissement des performances des équipements de Traction ferroviaire, reposait essentiellement jusqu'à maintenant, sur l'intégration des innovations dans le domaine des composants électriques et des matériaux diélectriques mais la standardisation de sous-ensembles réutilisables nous conduit à reconsidérer les assemblages structuraux des coffres de traction (convertisseurs de puissance). Ces coffres de traction sont assemblés actuellement avec des éléments de fixation mécanique (boulon, rivet), le but est donc d'améliorer la connaissance des comportements mécaniques de ces types d'assemblages à travers d'une étude expérimentale basée sur des essais statiques et dynamiques sur des joints boulonnés et rivetés. Ces essais nous ont permis de valider des modèles numériques par des éléments finis en utilisant les codes de calcul ABAQUS et ANSYS. La deuxième partie de la thèse concerne les assemblages par collage structural. Nous avons étudié la possibilité de remplacer les assemblages mécaniques classiques par l'assemblage par collage structural. La première phase de notre travail a été de recenser et sélectionner des adhésifs structuraux susceptibles de répondre à notre cahier de charge. Dans cette partie les travaux suivants ont été réalisés : - Etude des comportements des adhésifs en tant que matériau, ce qui a nécessité de réaliser des éprouvettes massiques. - Réalisation d'essais expérimentaux en statique et en dynamique sur des joints collés avec l'adhésif sélectionné. - Création des modèles numériques non linéaires en 3D sur ABAQUS pour les joints collés. - Etude hygrothermique accélérée afin d'étudier l'effet du vieillissement sur les assemblages collés en fonction de l'humidité et de la température. / Increased performance of railway traction equipment, until now relied primarily on the integration of innovations in the field of electrical and dielectric materials, but the standardization of subassemblies reusable us to reconsider the structural assemblies of the traction cubicles (power converters). These cubicles are assembled now with mechanical fasteners (bolts, rivets), the first goal is to improve knowledge of the mechanical behaviour of these types of joints through an experimental study based on statics and dynamics tests of bolted and riveted joints. These tests have allowed us to validate numerical models of finite elements by using the computer codes ABAQUS® and ANSYS®. The second part of the thesis deals with the structural adhesive joints. We studied the possibility of replacing conventional mechanical assembly structural bonding. The first phase of our work was to identify and select structural adhesives that could meet our specifications. In this section the following work has been made: - Study of thermo-mechanical behaviour of the adhesive with the bulk Adhesive Test Specimens. - Statics and dynamics test in the bonded joint. - Non-linear 3D finite elements models. - Hygrothermal accelerated to study the effect of aging on the adhesive according to the humidity and temperature.

Este trabalho apresenta uma investigação de modelos analíticos de previsão da força de tração resistente para ligações parafusadas em chapas finas e perfis de aço formados a frio, de acordo com quatro especificações de projeto (ABNT NBR 14762:2010, ANSI AISI S100:2007-S, AS/NZS 4600:2005 e EUROCODE 3 Parte1.3:2010). O estudo envolveu 404 resultados experimentais de ligações parafusadas, sendo: 232 ligações em chapas finas, 104 ligações em cantoneiras e 68 ligações em perfis U, em que diversas configurações geométricas foram analisadas. No total 1616 análises de força resistente foram realizadas de modo que estatísticas da variável aleatória erro de modelo pudessem ser construídas. Dessa forma, a análise de erro de modelo consistiu da plotagem das probabilidades do erro de modelo, para que em seguida testes de aderência pudessem ser então aplicados de modo satisfatório, validando funções teóricas de distribuição de probabilidades para a representação da informação estatística dessa variável aleatória. Uma análise de regressão foi utilizada nas ligações parafusadas para descrever a variação do erro de modelo com a espessura da chapa e para descrever a incerteza de modelo. As análises realizadas mostraram que os modelos brasileiros e americanos conseguem prever, em média, a ruptura da seção líquida de maneira mais eficiente do que as outras especificações, pois utilizam coeficientes de redução da área líquida, e também apontam que todos os modelos apresentam uma grande variabilidade dos resultados em torno da média, o que faz com que a confiabilidade dos modelos seja prejudicada. A análise de confiabilidade, utilizada para avaliar o nível de segurança das especificações de projeto, incluiu o erro de modelo e outros parâmetros aleatórios como a resistência à ruptura do aço, ação permanente (D) e variável (L), totalizando 7092 análises em ligações parafusadas, revelando que a contribuição da variável aleatória erro de modelo na segurança dessas ligações é considerável, especialmente para razões de carregamento (Ln/Dn) entre 0,50 e 2,50. Cabe ainda observar que as especificações de projeto foram avaliadas de acordo com critérios de confiabilidade uniforme e suficiente, demonstrando que a uniformidade é alcançada de maneira mais fácil para as quatro especificações, para razões de carregamento (Ln/Dn) maiores que 2,0, e que a suficiência de segurança, na maioria das análises realizadas, não foi alcançada, principalmente para o modo de ruína de esmagamento da parede do furo, em que os índices de confiabilidade para as ligações situaram-se em torno de 2,0 a 2,5, abaixo do valor alvo de 3,5 estabelecido pelo AISI e 3,8 estabelecido pelo EUROCODE. Além disso, ao se tratar da ruptura da seção líquida, os modelos brasileiro, americano e australiano também não atingiram níveis desejáveis de segurança, contudo, fornecem probabilidades de falha bem abaixo das obtidas para o modo de ruína de esmagamento. Por fim, análises de sensibilidade revelaram que os parâmetros x/L e d/g, presentes nos modelos analíticos de previsão da ruptura da seção líquida, para a especificação brasileira e americana, não interferem na segurança estrutural das ligações. / This work presents an investigation of analytical models for predicting the tensile strength to bolted connections in thin sheets and cold-formed steel members, according to four design specifications (ABNT NBR 14762:2010, ANSI AISI S100:2007-S, AS/NZS 4600:2005 and Eurocode 3 Parte1.3:2010). The study involved 404 experimental results of bolted connections, as follows: 232 connections in thin sheets, 104 connections in angles and 68 connections in channels, in which various geometric configurations were analyzed. A total of 1616 strength analysis were performed so that statistics of the random variable model error could be constructed. Thus, the model error analysis consists of plotting the probability of error model, then for the adherence tests could then be applied satisfactorily validating theoretical functions of probability distribution for the statistical representation of random variable. A regression was used in bolted connections to describe the variation of the model error with the thickness of the sheet and to describe the model uncertainty. The analysis showed that the models can predict Brazilians and Americans, on average, net section fracture more efficiently than the other specifications, for use of coefficient of reduction of net area, and also note that all models showed a great variability of results around the mean, which makes the reliability of the models is affected. The reliability analysis used to assess the safety level of design specifications, included the model error and other random parameters such as tensile strength of steel, dead (D) and live (L) loads, totaling 7092 analysis on bolted connections, revealing that the contribution the random variable model error in the security of these connections is considerable, especially for load ratios (Ln/Dn) between 0.50 and 2.50. It should also be noted that the design specifications were evaluated according to sufficient and uniform reliability criteria showing that uniformity is achieved more easily for the four specifications, for load ratios (Ln/Dn) higher than 2.0, and that the sufficiency of security, most of the analysis, is not achieved, especially for the failure modes of bearing of the hole, in which the reliability index for the connections are located around 2.0 to 2.5, below the target value of 3.5 indicated by AISI and 3.8 indicated by EUROCODE. Furthermore, when dealing with the net section fracture, the models Brazilian, American and Australian also did not reach desirable levels of security, however, provided failure probabilities well below those obtained for the failure modes of bearing. Finally, sensitivity analysis revealed that the parameters x/L and d/g, present in the analytical models for predicting the net section fracture, the specification for Brazilian and U.S., do not affect the structural safety of the connections.