Schneckenradgetriebe sind aufgrund ihrer Verzahnungsgeometrie prädestiniert für Getriebeanwendungen mit diskontinuierlichem und schwingungsbehaftetem Betrieb. Bei hohen Momenten und geringen Drehzahlen stellt dabei die Zahnfußtragfähigkeit die primäre Auslegungsgrenze dar. Das Ziel der vorliegenden Arbeit lag in der Erhöhung der Genauigkeit der Berechnungsmethoden für die Zahnfußtragfähigkeit von Schneckenrädern, auch zur Steigerung des Volumennutzwertes dieser Getriebe. Hierzu wurden alle die Tragfähigkeit des Zahnfußes beeinflussenden Parameter durch eine Vielzahl von Experimenten und FE Simulationen untersucht. Dies schließt eine genaue Analyse der Geometrie von Schneckengetrieben, deren Fertigung und Einbausituation, die verwendeten Werkstoffe und deren Beanspruchung mit ein. Auf dieser Basis gelang neben der Entwicklung eines vergleichsspannungsbasierten analytischen Berechnungsverfahrens die Erstellung eines örtlichen Berechnungskonzeptes nach dem Kerbspannungskonzept. Hiermit konnte die Einschätzung der Zahnfußtragfähigkeit bei der Neuentwicklung und die Optimierung von Getrieben verbessert werden. / Worm gears are well suited for gearbox applications in environments with discontinuous conditions and mechanical vibrations. In the case of high torque and low speed, the tooth root strength is the primary design limit. The aim of the present paper is to improve the accuracy of the calculation methods for the tooth root strength of worm wheels. To reach this, all parameters which affects the strength of the tooth root were examined. This includes the geometry, the manufacturing, the materials and the stresses of worm wheels. Through this investigation, the development of a new analytical calculation method based on the equivalent stress concept could be done. Furthermore, a local calculation method based on the notch stress concept was developed. Thus, the forecast of the tooth root strength of worm wheels for redevelopment and optimization could be improved.

The official recommendations in geotechnical engineering are according to Swedish practice to install inclined driven piles in order to resist external horizontal loads, which usually consist of windloads. These loads gets counteracted by utilizing the pile's axial load-bearing capacity, however when designing a foundation the use of inclined piles has proven to be problematic from a number of different perspectives. This has made both engineers as well as contractors long for a solution where the piles instead are allowed to be installed vertically, which could be made possible by utilizing the lateral bearing capacity of the pile which occurs in connection with lateral resistance during pile-soil interaction. The present day knowledge about such an engineering procedure in Sweden has proven to be limited and consists mainly of one governing document, namely report 101 published by the Commission on Pile Research. The aim of our study is to test and evaluate the method in report 101 based on a number of different load cases related to lateral load effects during pile-soil interaction. An analytical method reproduced from the Commission on Pile Research's report has been implemented with help of Mathcad, a computer software for reuse of mathematical calculations. Decisive parameters that distinguish the different load cases have included external load impact in pile head, mechanical strength properties of friction or cohesive soil, along with cross-sectional dimensions and reinforcement content of piles etc. The results differed significantly depending on the loadcase, a majority of the given answers were also perceived as unreliable and in a number of load cases the method also failed to obtain an analytical solution. Our conclusion is that it is doubtful whether the elastoplastic method presented in report 101 in the end in practice benefits the engineer tasked with designing, this stands in stark contrast to an increasing demand for easily accessible knowledge within its field. / Pålar i samband med grundläggning har sedan en tid tillbaka enligt svensk praxis installerats snedslagna, detta för att med hjälp av pålens axiella bärförmåga motstå yttre horisontell lastpåverkan till följd av exempelvis vindlaster. Att snedställa pålar har visat sig vara problematiskt ur ett flertal olika perspektiv, en lösning som både konstruktörer och entreprenörer efterlängtat är att pålarna istället tillåts installeras rakställda. Detta skulle vara möjligt genom att nyttja pålens transversella bärförmåga som uppstår i samband med sidomotstånd vid interaktion påle-jord. Kunskap kring ett sådant dimensioneringsförfarande i Sverige idag har visat sig vara begränsad och till stor del bestå av ett styrande dokument, nämligen rapport 101 utgiven av Pålkommissionen. I denna studie har en analytisk handberäkningsmetod som återges ur Pålkommissionens rapport implementerats i beräkningsprogrammet Mathcad, detta i syfte att testa och utvärdera metoden utifrån ett flertal olika belastningsfall relaterade till transversell lastpåverkan vid interaktion påle-jord. Avgörande parametrar som skiljt de olika belastningsfallen åt har bl.a. utgjorts av hållfasthetsegenskaper hos friktion- eller kohesionsjord, tvärsnittsdimensioner och armeringsinnehåll hos påle, yttre lastpåverkan i påltopp. Resultaten skiljde sig åt markant beroende på typ av belastningsfall där en majoritet av svaren upplevdes som icke tillförlitliga och till ett flertal olika fall, utifrån vårt försök till implementering, klarade metoden heller inte av att erhålla någon analytisk lösning. Vi finner det därför svårt att tro att den elastoplastiska metoden som återges i rapport 101 i slutändan kommer till någon direkt praktisk nytta, vilket står i tvär kontrast mot ett uppenbart behov där lättillgänglig kunskap inom området efterfrågas.

The research is motivated by the need to address two major challenges in wind power integration: how to mitigate wind power fluctuation and how to ensure stability of the farm and host grid. It is envisaged that wind farm power output fluctuation can be reduced by using a specific type of buffer, such as an energy storage system (ESS), to absorb its negative impact. The proposed solution, therefore, employs ESS to solve the problems. The key research findings include a new technique for calculating the desired power output profile, an ESS charge-discharge scheme, a novel direct-calculation (optimization-based) method for determining ESS optimal rating, and an ESS operation scheme for improving wind farm transient stability. Analysis with 14 wind farms and a compressed-air energy storage system (CAES) shows that the charge-discharge scheme and the desired output calculation technique are appropriate for ESS operation. The optimal ESSs for the 14 wind farms perform four or less switching operations daily (73.2%-85.5% of the 365 days) while regulating the farms output variation. On average, the ESSs carry out 2.5 to 3.1 switching operations per day. By using the direct-calculation method, an optimal ESS rating can be found for any wind farm with a high degree of accuracy. The method has a considerable advantage over traditional differential-based methods because it does not require knowledge of the analytical form of the objective function. For ESSs optimal rating, the improvement in wind energy integration is between 1.7% and 8%. In addition, a net increase in grid steady-state voltage stability of 8.3%-18.3% is achieved by 13 of the 14 evaluated ESSs. For improving wind farm transient stability, the proposed ESS operation scheme is effective. It exploits the use of a synchronous-machine-based ESS as a synchronous condenser to dynamically supply a wind farm with reactive power during faults. Analysis with an ESS and a 60-MW wind farm consisting of stall-regulated wind turbines shows that the ESS increases the farm critical clearing time (CCT) by 1 cycle for worst-case bolted three-phase-to-ground faults. For bolted single-phase-to-ground faults, the CCT is improved by 23.1%-52.2%. / text

Les ponts roulants sont des engins de levage situés en haut des bâtiments qu'ils équipent. Ils servent à manutentionner des charges très lourdes et parfois critiques. Pendant un séisme, un pont roulant est exposé à des chocs multiples. Ces impacts peuvent causer des dommages importants dans la structure pouvant conduire à une chute de la charge manutentionnée ou du pont roulant lui-même. Donc, la vérification de la tenue des ponts roulants au séisme est une question primordiale. Actuellement, cette vérification est basée sur des méthodes de calcul statiques. Ces méthodes font l'hypothèse d'un comportement purement linéaire des ponts roulants ce qui les rend très conservatives. Depuis quelques années les niveaux sismiques imposés par les autorités nationales augmentent chaque année, et les constructeurs de ponts roulants se trouvent dans l'incapacité de construire à partir des efforts sur-estimés fournis par les méthodes statiques. L'objectif de la thèse est l'étude de la réponse dynamique d'un pont roulant pendant un séisme en prenant en compte les non-linéarités géométriques et matériau. Afin de modéliser ces phénomènes, une analyse dynamique temporelle avec une approche multi-échelle en temps est adoptée. Pour prendre en compte l'aspect haute fréquence des chocs, un intégrateur temporel variationnel explicite, basé sur la méthode des multiplicateurs de Lagrange et dédié au contact/impact, est développé. Ensuite, un intégrateur hétérogène (différents schémas d'intégration) asynchrone (différents pas de temps), basé sur la méthode de couplage GC, est appliqué au problème du pont roulant. Cette stratégie multi-échelle en temps permet d'adapter le schéma d'intégration et le pas de temps au sous domaine considéré. Par conséquent, l'intégrateur explicite est adopté dans les zones de contact et un schéma implicite de type accélération moyenne, est adopté dans le reste de la structure. Finalement, un démonstrateur de co-simulation entre les logiciels Cast3M et Europlexus est mis en place pour montrer le gain très significatif en temps de calcul dans le cas d'un modèle élément finis tridimensionnel d'un pont roulant industriel. / Bridge cranes are hoisting appliances located overhead in buildings. They are used to handle very heavy and sometimes critical loads. During an earthquake, a bridge crane may be subjected to multiple impacts between wheels and rails. These impacts can cause significant damage to the structure leading to a fall of the handled load or the bridge crane itself. Therefore, the qualification of such equipment, subjected to an earthquake, is very important. Currently, this qualification is based on static methods. These methods assume a purely linear behavior of the bridge cranes, which leads to a very conservative forces. Consequently, the bridge cranes manufacturers are sometimes unable to design the equipement from the over-estimated efforts provided by the static methods. The aim of this work is to study the dynamic response of a bridge crane during an earthquake by taking into account the geometric and material non-linearities. In order to model such phenomena, a time-history dynamic analysis with a multi-scale approach is performed. To take into account the high frequency aspect of the impacts between wheels and rails, a Lagrange explicit contact/impact time integrator is proposed. This work has also led to the development of an explicit–implicit HATI (Heterogeneous Asynchronous Time Integrator) for contact/impact dynamics. This method allows us to adopt an explicit contact/impact time integrator in the contact area and an implicit time integrator with a coarse mesh in the rest of the domain. Finally, a co-simulation demonstrator between Cast3M and Europlexus softwares is set up to show the very significant gain in computation time for a three-dimensional finite element model of an industrial bridge crane.