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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.
1

Stacionární drtič železobetonových panelů - analýza dynamických účinků do základů stroje / Stationary crusher concrete panels - analysis of dynamic effects in the machine foundations

Macejka, Andrej January 2019 (has links)
This diploma thesis is concerned with design and proposal of parameters of drop hammer Davon for crushing of steel reinforced concrete panels with weight of the ram 5 t. The main topic is an emergency condition when there is no crushed material between ram and anvil. The design is established by simulation of an impact by finite element analysis with respect to required ground bearing capacity.
2

Análise vibratória de fundações de máquinas sobre estacas. / Vibration Analysis of machine foundation on piles.

Guilherme Alan Souza Costa 27 September 2013 (has links)
Fundação Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de Janeiro / A análise de fundações sob solicitações dinâmicas é algo sempre presente em projetos na área industrial. É um campo pouco explorado na área de engenharia geotécnica, onde existem relativamente poucas informações no Brasil, de maneira geral. O método mais comum de realizar essas análises é a simplificação de modelos estruturais a partir do uso de molas. Sabe-se que esses coeficientes de reação têm uma variação relativamente grande e que esse enfoque de projeto pode, em alguns casos, mostrar-se contra a segurança ou levar a superdimensionamentos desnecessários. Verifica-se, então, a necessidade de uma avaliação mais criteriosa, utilizando a interação solo x estrutura, onde as molas comumente utilizadas nas análises vibratórias convencionais são substituídas pela rigidez real do solo quando concebido como um meio contínuo, através de sua discretização pelo método dos elementos finitos. A presente dissertação analisa o problema através do módulo de dinâmica do programa Plaxis 2D. Neste tipo de análise, além da modelagem do solo como um meio contínuo, torna-se possível introduzir condições de contorno específicas ao problema em estudo, múltiplas camadas de solo, sejam horizontais ou inclinadas, além da introdução de amortecedores capazes de evitar a reflexão espúria das ondas incidentes nos limites da malha de elementos finitos e assim modelar mais adequadamente a perda de energia por radiação. A presente dissertação compara medições experimentais e soluções eficientes de métodos vibratórios clássicos com a resposta obtida pelo MEF, mostrando resultados bastante satisfatórios tanto pelos métodos clássicos quanto pelo MEF. / The foundation analysis by dynamic solicitations is always present in industrial projects. It is an area which is poorly explored in geotechnical engineering and there are few information about this subject in Brazil, in general. The most common method to realize this analysis consists in simplifies structural models by using springs. It is known that these reaction coefficients have a large range of variation and this projects focus can, in some cases, be against the safety side or lead to unnecessary over designs. This proves the necessity to do a more criterious evaluation by using the interaction soil x structure where the springs usually used in common vibration analysis are replaced by the real stiffness of soil when designed as a continuous medium through its discretization by finite element method. This present dissertation analyzes the problem through the dynamic modulus of the software PLAXIS 2D. In this sort of analysis, besides the modeling of soil as a continuous medium, it becomes possible to introduce specific boundary conditions associated to the studied problem, multiple soil layer, that can be horizontals or inclined, in addition to the introduction of dampers able to avoid the spurious reflection of incident waves on the boundary of finite element mesh and then to model more efficiently the energy loss by radiation. This present dissertation compares experimental measurements and efficient solutions of classical vibration methods with the response obtained by FEM, showing results quite satisfactory both by classical methods and by FEM.
3

Análise vibratória de fundações de máquinas sobre estacas. / Vibration Analysis of machine foundation on piles.

Guilherme Alan Souza Costa 27 September 2013 (has links)
Fundação Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de Janeiro / A análise de fundações sob solicitações dinâmicas é algo sempre presente em projetos na área industrial. É um campo pouco explorado na área de engenharia geotécnica, onde existem relativamente poucas informações no Brasil, de maneira geral. O método mais comum de realizar essas análises é a simplificação de modelos estruturais a partir do uso de molas. Sabe-se que esses coeficientes de reação têm uma variação relativamente grande e que esse enfoque de projeto pode, em alguns casos, mostrar-se contra a segurança ou levar a superdimensionamentos desnecessários. Verifica-se, então, a necessidade de uma avaliação mais criteriosa, utilizando a interação solo x estrutura, onde as molas comumente utilizadas nas análises vibratórias convencionais são substituídas pela rigidez real do solo quando concebido como um meio contínuo, através de sua discretização pelo método dos elementos finitos. A presente dissertação analisa o problema através do módulo de dinâmica do programa Plaxis 2D. Neste tipo de análise, além da modelagem do solo como um meio contínuo, torna-se possível introduzir condições de contorno específicas ao problema em estudo, múltiplas camadas de solo, sejam horizontais ou inclinadas, além da introdução de amortecedores capazes de evitar a reflexão espúria das ondas incidentes nos limites da malha de elementos finitos e assim modelar mais adequadamente a perda de energia por radiação. A presente dissertação compara medições experimentais e soluções eficientes de métodos vibratórios clássicos com a resposta obtida pelo MEF, mostrando resultados bastante satisfatórios tanto pelos métodos clássicos quanto pelo MEF. / The foundation analysis by dynamic solicitations is always present in industrial projects. It is an area which is poorly explored in geotechnical engineering and there are few information about this subject in Brazil, in general. The most common method to realize this analysis consists in simplifies structural models by using springs. It is known that these reaction coefficients have a large range of variation and this projects focus can, in some cases, be against the safety side or lead to unnecessary over designs. This proves the necessity to do a more criterious evaluation by using the interaction soil x structure where the springs usually used in common vibration analysis are replaced by the real stiffness of soil when designed as a continuous medium through its discretization by finite element method. This present dissertation analyzes the problem through the dynamic modulus of the software PLAXIS 2D. In this sort of analysis, besides the modeling of soil as a continuous medium, it becomes possible to introduce specific boundary conditions associated to the studied problem, multiple soil layer, that can be horizontals or inclined, in addition to the introduction of dampers able to avoid the spurious reflection of incident waves on the boundary of finite element mesh and then to model more efficiently the energy loss by radiation. This present dissertation compares experimental measurements and efficient solutions of classical vibration methods with the response obtained by FEM, showing results quite satisfactory both by classical methods and by FEM.
4

Prodejní a servisní centrum Praha – stavebně technologický projekt / Sales and service center Prague - the building technological project

Trhlík, Lukáš January 2012 (has links)
In this diploma thesis deals with execution of ground works, foundation constructions, steel and armored concrete monolithic framework of the sales and service center in Prague. Establishment of the building will be done on armored concrete basement feet, strips and basement plate. The building is desinged in part as a steel framework and in part as a armored concrete framework. The building technological project contains for the phases primarily time and financial plan of object, technology prescription, time schedule, budget, model of the building site accessories, model of the machines, check and test plan, safety plan.
5

Linear FEM Analysis of a Commercial Elastomer for Machine Foundations

Jakel, Roland 20 June 2024 (has links)
The presentation describes partial results from an industrial project in which a transmission test bench from ZF Prüfsysteme was decoupled from the foundation in terms of vibration using commercial PU foam material ('Sylomer' SR220 from Getzner). The presentation shows how this material was extensively tested by the manufacturer and characterized in numerous data sheets in order to enable the engineer to perform a simple, operating point-dependent dynamic design using clear diagrams and the classic equation for a single-mass oscillator. However, if a more complex analysis is to be carried out using the finite element method, e.g. to determine all 6 rigid body shapes and natural frequencies of the dynamically decoupled test rig and not just the purely vertical natural shape/frequency, the apparent elasticity and shear moduli specified in the manufacturer's data sheets must be converted into true values for the corresponding operating points, which can then be used in a linear FE calculation. For this purpose, FEM models of the elastomer test specimens are generated for different shape factors. The conversion of the apparent to the true characteristic values is then carried out using the optimizer available in the PTC software “Creo Simulate” in a so-called 'feasibility study' and the results are discussed. It can be seen that the true moduli of elasticity and transverse strain coefficients are only slightly or no longer dependent on the form factor. Depending on the density of the PU foam, the transverse strain coefficient is also significantly lower than 0.5. The true shear modulus is practically identical to the measured shear modulus, as a pure biaxial stress and strain state occurs in the shear specimens, in which strain restraints due to transverse strain plays no role - quite unlike in the specimens loaded in the normal (compression) direction, in which triaxial compression stress states occur due to transverse strain restraints. Finally, the true material properties determined in this way are used for an exemplary modal analysis of the entire, idealized test rig on the strip foundation using the finite element method. The error is evaluated if the apparent modulus of elasticity and a Poisson ratio of zero is used instead, so that a simple evaluation and error estimation of analysis results is possible in practical applications. / Der Vortrag beschreibt Teilergebnisse aus einem industriellen Projekt, in dem ein Getriebeprüfstand der ZF Prüfsysteme schwingungstechnisch über kommerzielles PU- Schaummaterial („Sylomer“ SR220 der Firma Getzner) vom Fundament abgekoppelt wurde. Der Vortrag stellt dar, wie dieser Werkstoff vom Hersteller umfangreich getestet und in zahlreichen Datenblättern charakterisiert wurde, um dem Ingenieur schließlich eine einfache, betriebspunktabhängige dynamische Auslegung mittels übersichtlicher Diagramme und der klassischen Gleichung für einen Einmassenschwinger zu ermöglichen. Soll jedoch eine aufwendigere Analyse mittels der Methode der Finiten Elemente durchgeführt werden, z.B. um alle 6 Starrkörperformen und Eigenfrequenzen des dynamisch abgekoppelten Prüfstandes zu bestimmen und nicht nur die rein vertikale Eigenform/Eigenfrequenz, müssen die in den Herstellerdatenblättern angegeben formzahlabhängigen scheinbaren Elastizitäts- und Schubmoduli in wahre Werte für die entsprechenden Betriebspunkte umgerechnet werden, die dann in einer linearen FE-Rechnung verwendet werden können. Dafür werden FEM-Modelle der Elastomer-Probekörper für verschiedene Formfaktoren erzeugt. Die Umrechnung der scheinbaren in die wahren Kennwerte wird anschließend mittels des in der PTC-Software „Creo Simulate“ vorhandenen Optimierers in einer sogenannten „Machbarkeitsstudie“ durchgeführt und die Ergebnisse diskutiert. Es zeigt sich, dass die wahren E-Moduli und Querdehnzahlen nur noch gering bzw. nicht mehr vom Formfaktor abhängen. Je nach Dichte des PU-Schaums stellt sich auch eine Querdehnzahl von deutlich kleiner als 0,5 ein. Der wahre Schubmodul ist praktisch identisch wie der gemessene Schubmodul, da in den Schubproben ein reiner zweiachsiger Spannungs- und Dehnungszustand auftritt, in dem Dehnungsbehinderung durch Querdehnung keine Rolle spielt – ganz anders als in den in Normalenrichtung (Druck-) belasteten Proben, in denen durch die Querdehnungs- behinderung dreiachsige Spannungszustände auftreten. Schließlich werden die so bestimmten wahren Werkstoffkennwerte für eine exemplarische Modalanalyse des gesamten, idealisierten Prüfstandes auf den Streifenfundamenten mittels der Methode der Finiten Elemente verwendet. Der Fehler wird bewertet, wenn man stattdessen den scheinbaren E-Modul und eine Querdehnzahl von Null verwendet, so dass in der Anwendungspraxis eine einfache Bewertung und Fehlerabschätzung von Analyseergebnissen möglich ist.

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