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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Deformačně-napěťová analýza tenkostěnné skříně vystavené rázovému zatížení od výbuchu / Stress-strain analysis of the thin wall structure subjected to impact load

Tatalák, Adam January 2016 (has links)
This master thesis deals with stress-strain analysis of simplified model of the thin wall transformer case subjected to impact load of electrical blast. Electrical blast is replaced by chemical blast (detonation of high explosive). The problem is solved using computational modeling utilizing the Finite Element Method (FEM) and LS-DYNA solver. After the introduction where detonation and shock wave propagation is explained the analytical approach is presented. This approach serves to results verification. In the next chapter is conducted research of applicable methods from which ALE method is chosen. In preliminary study is performed the mesh size analysis that is focused on finding the size of element which is both computational effective and gives accurate results. Next the infulence of input conditions (shape, location and parametres of high explosive, location of detonation point, boundary conditions) on distribution and time progress of pressure is investigated. Then influence of the opening on upper side of the case on overall pressure redistribution and strain and stress of the case is analysed. The stress-strain analysis of the case´s door which are connected to case by various types of contact models is performed as well as stiffness analysis of these types of contact.
52

Návrh metodiky výpočtu životnosti valivého ložiska / Design of the computational lifetime prediction methodology for the roll bearing

Vaculka, Miroslav January 2016 (has links)
This master’s thesis deals with a fatigue analysis of a roller bearing. The fatigue analysis consists of determining service-life of a roller bearing using a stress-strain analysis with finite element method and subsequent numeric calculation using software fe-safe with application of Brown-Miller multiaxial fatigue criterion. Service-life of a roller bearing is determined by number of cycles to failure in the form of pitting formation which is consequence of contact fatigue. According to calculations was found an inappropriateness of Brown-Miller criterion for high-cycle contact fatigue. Test of other available criteria was performed. Principal-Strain criterion provided the best match with ISO 281 standard.
53

Pevnostní posouzení konstrukce výřezu dveří přetlakovatelného habitatu pro extrémní prostředí / Pevnostní posouzení konstrukce výřezu dveří přetlakovatelného habitatu pro extrémní prostředí

Sláma, David January 2017 (has links)
Main goals of this master thesis are following: to perform the state of the art research of overpressure constructions (especially space habitats, plane fuselages); to create an own concept of the functional inside ending (hole) in the sandwich panel for a door; to perform stress-strain analysis of this concept; to perform the design optimalization of this concept in order to minimise the weight. To solve the problems above software Ansys 17.2 is chosen, because it allows to: model the material of the honeycomb core of sandwich panel as homogenous linear orthotropic material; evaluate reserve factors of all critical limit states; perform the design optimalization; perform Monte Carlo simulation. First and second design optimalizations discover, that with defined parameters: 0,635 mm width of aluminium sandwich face sheets and inner overpressure 0,1 MPa, a creation of the model, that would be safe by changing the values of design variables is not possible. Specifically, the maximum value of shear stress on the glued areas between aluminium face sheets and honeycomb core is higher than the shear strength of the glue. Therefore, two new concepts are created. First for inner pressure 0,03 MPa and bigger width of aluminium face sheets 3,175 mm, second for inner pressure 0,02 MPa and same width of aluminium face sheets 0,635 mm. For both these concepts, an overall reserve factor is calculated. First, the value of an overall reserve factor is calculated deterministically. Secondly, the value of an overall reserve factor is calculated stochastically considering the variance of material properties of the honeycomb core ± 10 % by Monte Carlo simulation. An overall reserve factor of the concept with inner pressure 0,02 MPa is determined as 1,21. An overall reserve factor of the concept with inner pressure 0,03 MPa is determined as 1,20. The weight of the concept for inner pressure 0,03 MPa is though 4 times bigger than the weight of the concept for inner pressure 0,02 MPa. In the concept for inner pressure 0,02 MPa the maximum value of HMH stress in aluminium components is critical, stochastically considered material properties of the honeycomb core don’t have a significant influence on this value. In the concept for inner pressure 0,03 MPa the value of maximum shear stress on the glued areas between aluminium face sheets and the honeycomb core is critical, stochastically considered material properties of the honeycomb core have a significant influence on this value. In the concept for inner pressure 0,03 MPa an absolute error of overall reserve factor is 8 % (overall reserve factor calculated deterministically was 1,28) which is significant. Monte Carlo simulation is also used to find that the value of Poisson ratio XY of the honeycomb core doesn’t have statistically significant influence on all limit states. Value of the reserve factor of the honeycomb core is higher than 2 in both concepts. Monte Carlo simulation discovers that this value can be significantly lower. Using Tsai-Wu failure criteria the reserve factor in the concept for inner pressure 0,02 MPa is determined as 2,72 deterministically x 2,41 stochastically (absolute error 31 %), in the concept for inner pressure 0,03 MPa the reserve factor is determined as 6,85 deterministically x 6,17 stochastically (absolute error 68 %).
54

Propuesta de diseño de muro de suelo reforzado como soporte de vías ferroviarias mediante técnicas numéricas en el tramo Mariscal Cáceres – Acoria del Ferrocarril Huancayo – Huancavelica / Design proposal for a reinforced soil wall as a support for railway tracks using numerical techniques in the Mariscal Cáceres – Acoria section of the Huancayo - Huancavelica Railway

Coria Urcia, Marjorie Lilibeth, Herquinio Meza, Will Bryan 23 November 2021 (has links)
En la actualidad, se puede observar situaciones en las que el terreno sufre constantes cambios debido a factores climáticos, geológicos, sísmicos, y demás fenómenos naturales, provocando movimientos que ocasionan la falla del talud. Por lo cual, cada proyecto de ingeniería debe tener como objetivo principal velar por la integridad del usuario final, interviniendo de manera adecuada en un diseño óptimo para cada situación, ya que esto depende de las características, condiciones y necesidades propias de cada proyecto, no dejando de lado la logística, aérea o terrestre, necesaria. El proyecto de ingeniería en el cual se enfoca la tesis es la “Rehabilitación Integral del Ferrocarril Huancayo Huancavelica”, donde el tramo de estudio elegido es entre las estaciones Mariscal Cáceres y Acoria. Este tramo analizado presenta socavación y deslizamientos o flujos que incrementan paulatinamente debido a las vibraciones ocasionadas por el paso del tren, por agentes naturales y climáticos. También, se evidencia la ausencia de estructuras de soporte y la falta de mantenimiento constante en las progresivas km 86+154 al km 86+208. Este problema puede traer consigo la falta de acceso de pasajeros y/o transporte de mercancías y mineral, a los pueblos que une la línea ferroviaria. Frente a la problemática en mención, existen varias opciones de reforzamiento estructural para el mejoramiento de la capacidad portante del suelo e incluso desde una visión más general existen diferentes tipos de muros de contención. Por ende, una solución óptima frente a nuestra problemática es el uso de suelos reforzados con paramento de gavión como estructura de soporte y protección. El diseño de muro de suelo reforzado para el tramo estudiado se realizó considerando la teoría de equilibrio límite de la metodología de “Diseño por Esfuerzos Admisibles” (ASD - Allowable Stress Design) basada en las recomendaciones de la guía FHWA-NHI-00-043 y las consideraciones en el método de diseño de la “American Association of State Highway and Transportation Officials” (AASHTO). La metodología ASD consiste en evaluar la estabilidad externa e interna en todos los esfuerzos límites de resistencia, mientras que la estabilidad global y el desplazamiento vertical u horizontal se evalúan en los estados límites de servicio. Para el análisis de la estabilidad del muro se utilizó los softwares SLIDE (equilibrio límite) y PLAXIS (elementos finitos), en el cual se concluye que el diseño propuesto de muro de suelo reforzado para la estructura ferroviaria en el tramo estudiado es estable, ya que los valores de los Factores de Seguridad (F.S.) superan los valores mínimos y el desplazamiento horizontal no supera al valor máximo permitido recomendado por la Federal Highway Administration en la publicación FHWA-NHI-00-043. / At present, situations can be observed in which the terrain undergoes constant changes due to climatic, geological, seismic factor s, and other natural phenomena, causing movements that cause the slope to fail. Therefore, each engineering project must have as its main objective to ensure the integrity of the end user, intervening appropriately in an optimal design for each situation, since this depends on the characteristics, conditions, and needs of each project, without leaving aside the necessary air or ground logistics. The engineering project on which the thesis is focused is the "Integral Rehabilitation of the Huancayo Huancavelica Railway", where the section of study chosen is between the Mariscal Cáceres and Acoria stations. This section analyzed presents landslides or debris flow that gradually increase due to the vibrations caused by the passage of the train; furthermore, there is evidence of the absence of support structures and the lack of maintenance in the progressive km 86+154 to km 86+208. This problem brings with it the lack of access for passengers and/or transport of merchandise and minerals, to the towns that the railway line connects. Faced with the problem in question, there are several options for structural reinforcement to improve the bearing capacity of the soil and even from a more general view there are different types of retaining walls. Therefore, an optimal solution to our problem is the use of reinforced soil as a support structure. The design of the reinforced soil wall for the section studied was carried out considering the theory of limit equilibrium of the methodology of "Design by Allowable Stress Design" (ASD - Allowable Stress Design) based on the recommendations of the guide FHWA-NHI- 00-043 and the considerations in the American Association of State Highway and Transportation Officials (AASHTO) design method. The ASD methodology consists of evaluating the external and internal stability in all the resistance limit stresses, while the global stability and the vertical or horizontal displacement are evaluated in the service limit states. For the analysis of the stability of the wall, the software SLIDE (limit equilibrium) and PLAXIS (finite elements) were used, in which it is concluded that the proposed design of reinforced soil wall for the railway structure in the studied section is stable since the values ​​of the Safety Factors (FS) exceed the minimum values ​​and the horizontal displacement does not exceed the maximum allowed value recommended by the Federal Highway Administration in publication FHWA-NHI-00-043. / Tesis
55

Biomechanická studie zubních implantátů pro sníženou densitu kostní tkáně / Biomechanical Study of Tooth Implants for Low Density Bone

Marcián, Petr January 2012 (has links)
This work deals with problem of dental implant area, where there are many problems at the dental implants application. The essential issue is the bone tissue quality at implant application, which sig-nificantly influences its deformation, tension and the possibility of subsequent implant failure. The knowledge of bone tissue mechanical properties of mandible and mandible with applied implant can significantly affect prediction of dental implant failure. The mechanical interaction can be described by variable determining deformation and tension of solved system. For this reason the computational modeling by using Finite Element Method was used for solving given problem. The computational model creation of solved system on the high resolution level is necessary for biomechanical assessment of implant failure, including bone tissue quality. For this purpose the biomechanical study was performed, which significantly spreads range of solved problem in this work afterwards. In this work the methodology, which describes assessment of bone tissue quality where the implant should be applied as well as mutual interaction, is presented. The results confirm necessity of bone tissue computational models creation on high resolution level including complex trabecular architecture. In this work the creation of trabecular structure computational model from data gained on micro-CT device is described. Further, the trabecular structure computational model was created on the 3D level with dental implant and the stress strain analysis was performed consequently. The last part of this work deals with introductory study of bone tissue modeling and remodeling.
56

Deformačně-napěťová analýza aneurysmatu břišní aorty / Stress-strain analysis of abdominal aortic aneurysm

Ryšavý, Pavel January 2011 (has links)
This thesis deals with problems of biomechanics of soft tissues, namely of stress-strain analysis of abdominal aortic aneurysm (AAA). The introduction describes briefly the possibility of aneurysm occurrence with a focus on an aneurysm in the abdominal aorta.
57

Biomechanická studie ruky / Biomechanical study of hand

Krpalek, David Unknown Date (has links)
This work deals with issue of human wrist and appropriate total wrist implant allowing a restoration of hand mobility approaching physiological condition after traumatic and degenerative diseases. Treating these diseases are very complex. These issues including a biological and medical issues. To determine the appropriate treatment method and select right total wrist implant is important to know the behavior the human wrist at all stages in terms of medical and biomechanical. For this reason, it was developed a biomechanical study including computation model of human wrist allowing solution of strain and stress of hand in physiological and pathological conditions and condition after total wrist implant. The frost remodeling of bone tissue was used for analysis of human wrist bone tissues and bone tissues after application of total wrist implant RE-MOTION™ Total Wrist.
58

Deformační a napěťová analýza dolní čelisti s aplikovaným fixátorem v důsledku deficitu kostní tkáně / Stress-strain analysis of mandible with applied fixator due to the missing bone tissue

Fňukal, Jan January 2017 (has links)
This thesis deals with the fixation of lower jaw with bone tissue defect using commercially produced fixator. Large defects of bone tissue are mainly caused due to the removal of bone tissue affected by tumor. These topics have been researched on the basis of the literature. Subsequently, stress strain analysis of the lower jaw with the applied fixation plate was performed. This analysis was solved by using computational modeling with variational approach, ie the finite element method. The work also describes in detail the procedure of creating model of geometry, model of material, model of boundary conditions and loads with subsequent solution of several computational models. The stress strain analysis was done for lower jaw with varying size of the removed bone tissue with applied reconstruction plate made of CP-Ti Grade 4 and for the lower jaw with the plate, which is made of -Ti-Mo. Finally, the influence of the mechanical properties of the callus during formation of new bone tissue (callus healing) on the stress and deformation of the solved system was evaluated.
59

Deformačně napěťová analýza TEP kyčelního kloubu – typ Santori / Stress - strain analysis of total hip replacement - type Santori

Huťka, Pavel January 2008 (has links)
Submitted Diploma thesis deals with stress-strain analysis of deformation proximal end of femur with applied total hip joint endoprosthesis (replacement) – shortcut type. To identify deformation and tensity (stress) was used computational simulation by method of final elements. Have been created two computational models TEP- type Santori and type DePuy Proxima. Geometry model Santori was created on low level model geometry through the use of X-ray photograph. Principle of geometry model type DePuy Proxima was real Femoral stem endoprosthesis which was scanned on scanner ATOS. Geometry of both these replacements were set up in program Rhinoceros 4.0 and then execute in program CatiaV5R17. Data for geometry model of femur were gained from CT chains. Material model of femur have been crated in two variants. The first one looks at structure bone tissues and the second one were created by Gruen´s zones. Femoral Stem was weighted by static equivalent resultant force acting in hip joint. Computational model of system and self solution, including depiction results, was done by ANSYS Workbench 11.0 for four model variants.
60

Deformačně napěťová analýza TEP kyčelního kloubu – typ Mayo / Stress - strain analysis of total hip replacement - type Mayo

Rýdel, Jiří January 2008 (has links)
This diploma thesis deals with hip endoprothesis, primarily with endoprothesis conservative Mayo. A part of this paper considers a study aimed at an anatomy, types and modern trends in endoprothetic. On the basis of this study, gained CT data and the help of systems Ansys Workbench, Rhino Ceros and Catia there was made a model of proximal part of femur and TEP Conservative Mayo. A computational model was build up afterwards, which was used for a stress-train analysis.

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