This thesis work intended to verify an analysis method for welded, thin-walled geometries. Guidelines for stress evaluation in welded structures exist and are standardised, but they are often verified for structures with higher plate thicknesses, such as those found in the offshore industry. Thinner structures are commonly analysed using the hotspot method, but questions still exist wherever the method is valid and can provide conservative results in thin-walled geometries.  One goal of the thesis work was to create a test plan to experimentally verify the results given by FE models of welded structures, as well as to investigate the strain gradient close to the weld toe. The plan, as well as two different welded specimens were designed and manufactured on which future analysis can be performed.  The hotspot method was also evaluated using FE analysis on geometries where two tubes were welded together with a T-joint with varying diameter, thickness and applied loads. A total of 13 different models were created using solid elements where hotspot stress extrapolation was evaluated using different extrapolation points and evaluation paths. In conclusion, it was found that the method provides a correct extrapolation of the geometric stress when stress extrapolation points at a distance of 0,4t and 1,0t from the weld toe are used (t=plate thickness). It was also found through the analysis that the geometric stress can be harder to differentiate from the non-linear part of the stress gradient for some profiles with a thickness of 0,89 mm. In some cases, this resulted in a small part of the non-linear stress being included in the extrapolation which increased the extrapolated hotspot stress. Comparisons between the hotspot stress and geometric parameters showed that stress concentration factors can be created which reduce the need for time-consuming FE models.

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The purpose of this project was to show the updated procedures and to make additions to the computer program called Tmin designed by E. I. DuPont De Nemours and Company. This program is used as a screening tool for determining the largest of the minimum pipe-wall thicknesses in a piping system. This project involved several additions that will be released in the next version of the Tmin computer program. The first major additions to be implemented are four alternating Stress-to-Number of cycles curves: Aluminum 1100, Aluminum 3003-0, Aluminum 6061-T6, and Nickel 200. In addition, procedures of the ASME for fatigue curve analysis and implementation of fatigue data were investigated. These four stress-to-number of cycles (S-N) fatigue curves were added to Tmin's internal Microsoft Access® database. Next, a 2-D vertical piping span configuration was incorporated. Finally, DuPont required a Microsoft Word® document output of the pipe-wall thickness data including the piping span model information. Other user-friendly additions were included. Since this computer program was to be American Society of Mechanical Engineers (ASME) compliant, a study of the ASME Pressure Vessel and Piping standards and codes was made to determine how pipe-wall thickness calculations were to be processed. The 2-D vertical piping span calculation procedures were investigated. Once the 2-D vertical piping span analysis was complete, the largest pipe-wall thickness value calculated were passed to a Microsoft Word® document. The last implementation is the inclusion of help files. Help file button additions in all input boxes allowed for the user to know exactly what was needed before a data entry was made. / Master of Science

Volcanic activity, and the resultant deposits and structures at the Earth's surface, are the outcome of the inner workings of underground magmatic plumbing systems. These systems, essentially, consist of magma reservoirs which supply magma to the surface through volcanic conduits feeding volcanic eruptions. The mechanics and structure of plumbing systems remain largely unknown due to the obvious challenges involved in inferring volcanic processes occurring underground from observations at the surface. Nevertheless, volcanologists are beginning to gain a deeper understanding of the workings and architecture of magmatic plumbing systems from geophysical observations on active volcanoes, as well as from geological studies of the erosional remnants of ancient volcanic systems. In this work, I explore the relationship between the structure and mechanics of shallow plumbing systems and the volcanic eruptions these systems produce. I attempt to contribute to the understanding of this complex relationship by linking geological and geophysical observations of an eroded basaltic subvolcanic system, and the eruptive and tectonic activity of an active volcano, with mathematical models of magma ascent and stress transfer. The remarkable exposures of the Carmel outcrop intrusions, near the San Rafael swell, southeast Utah, U. S. A., allow detailed geological and geophysical observations of the roots of volcanic conduits that emerge from a subhorizontal magma feeder reservoir. These observations reveal a new mechanism for magma ascent and eruption triggering through gravitational instabilities created from an underlying feeding sill, and shed light on the mechanics of sill emplacement. Geophysical and geological observations of the 1999 and xii 1992 eruptions of the Cerro Negro volcano, Nicaragua, are used to explore the coupling between changes in the stress field and the triggering of volcanic eruptions, and magma ascent through the shallow crust. Modeling results of stress transfer and conduit flow highlight the importance of the surrounding stress field and geometry of the volcanic conduits that comprise shallow plumbing systems.

This thesis is concerned with static and dynamic stress calculation of busbar and wire conductors in HV and EHV substations according to standards ČSN EN 60865-1 ed. 2 and ČSN EN 50341-1 ed. 2. Calculations are done in program made in MS Excel with consideration to corporate regulations of energetics. In introduction is described the construction of HV substations and methodical step-by-step computation. Practical evaluation is applied to the substation R110 kV Dluhonice, where has to be checked up sufficient short-circuit resistance because of short-circuit strength increasing. At the end is analysed the influence of the spring structure constant on short-circuit strength forces in substation. Highly significant utility is the founded program for HV substations designations.

En région montagneuse, les infrastructures et les voies de communications sont soumises à de nombreux risques naturels dont les phénomènes d’origine gravitaire. Au-delà du danger pour les usagers, les conséquences des interruptions du trafic deviennent problématiques d’un point de vue économique et il devient indispensable de sécuriser les itinéraires. La mise en place d’écrans de filets pare-pierres est une des solutions possibles pour la protection contre les éboulements rocheux. Cette thèse porte sur l’étude des écrans souples ou filets métalliques de protection contre les chutes de blocs et plus précisément sur l’écran développé par l’entreprise GTS. Le filet constitutif de ces écrans se différencie par rapport aux systèmes conventionnels par un comportement orthotrope, dû à un maillage spécifique. Dans cette étude nous caractérisons le comportement de ces écrans de filets sous des chargements statiques et dynamiques de type impact par une approche couplant l’expérimentation et la modélisation numérique. L’étude procède pas à pas, les divers constituants sont évalués de façon quasi-statique, en laboratoire, et également in-situ pour reproduire les conditions réelles d’utilisation, en particulier l’aspect dynamique. Une attention particulière concernant les dissipateurs d’énergie, qui représentent l’élément centrale de ce type de structure, nous a permis de mettre au point un élément fusible robuste et fiable. Une campagne d’essais en grandeur réel sur les écrans de filets étudiés a permis de valider deux classes énergétiques (3000 kJ et 5000 kJ) selon les recommandations européennes. Les données recueillis lors des expérimentations ont permis de calibrer et valider différentes modélisations numériques de type éléments finis et éléments discrets. La pertinence de la modélisation a été évaluée au niveau des différentes échelles étudiées, échelle d’une maille, échelle d’une nappe, échelle du dissipateur d’énergie et échelle de la structure entière. Les performances et les limites des deux approches, MEF (méthode des éléments finis) et MED (méthodes des éléments discrets) ont été évaluées pour ce qui est de nos modélisations. / In mountainous areas, infrastructures, roads and railways are subject to various natural hazards due to the gravitational phenomena. Beyond the danger to users, the consequences of traffic interruptions becomes, from an economic point of view, more and more problematic and it becomes essential to secure these itineraries. An existing method to protect against the rockfall is to set up rockfall barriers made by metallic nets. This thesis focuses on the study of the rockfall protection barriers made by metallic net developed by the company GTS. The net of these barriers is different compared to conventional systems by an orthotropic behavior, due to a special form of the mesh. In this study we characterize the behavior of these barriers under static and dynamic loading (impact) by an approach combining the experimentation and the numerical modeling. The study proceeds step by step, the components are evaluated in quasi-static, in laboratory, and also in-situ to simulate the real conditions of use, especially the dynamic aspect. A special attention concerning the energy dissipators, which represent the principal element of this structure, has enabled us to develop a robust and reliable fuse element. A campaign of full-scale tests on the studied rockfall barriers allows the validation of two energy classes (3000 kJ and 5000 kJ) according to the European recommendations. The data collected during experiments permits to develop various numerical models of finite elements and discrete elements. The relevance of the modelisation was evaluated at the different studied scales, the mesh scale, the net scale, the energy dissipators scale and the scale of the entire structure.

<div>This body of work examines analytical and numerical models to simulate the response of structures in shock absorption applications. Specifically, the work examines the prediction of cushion curves of polymer foams, and a topological examination of a $\chi$ shape unit cell found in architected mechanical elastomeric metamaterials. The $\chi$ unit cell exhibits the same effective stress-strain relationship as a closed cell polymer foam. Polymer foams are commonly used in the protective packaging of fragile products. Cushion curves are used within the packaging industry to characterize a foam's impact performance. These curves are two-dimensional representations of the deceleration of an impacting mass versus static stress. The main drawback with cushion curves is that they are currently generated from an exhaustive set of experimental test data. This work examines modeling the shock response using a continuous rod approximation with a given impact velocity in order to generate cushion curves without the need of extensive testing. In examining the $\chi$ unit cell, this work focuses on the effects of topological changes on constitutive behavior and shock absorbing performance. Particular emphasis is placed on developing models to predict the onset of regions of quasi-zero-modulus (QZM), the length of the QZM region and the cushion curve produced by impacting the unit cell. The unit cell's topology is reduced to examining a characteristic angle, defining the internal geometry with the cell, and examining the effects of changing this angle.</div><div>However, the characteristic angle cannot be increased without tradeoffs; the cell's effective constitutive behavior evolves from long regions to shortened regions of quasi-zero modulus. Finally, this work shows that the basic $\chi$ unit cell can be tessellated to produce a nearly equivalent force deflection relationship in two directions. The analysis and results in this work can be viewed as new framework in analyzing programmable elastomeric metamaterials that exhibit this type of nonlinear behavior for shock absorption.</div>