O estudo do comportamento do concreto nas primeiras idades está se tornando cada vez mais importante, pois os efeitos térmicos e de retração do concreto, neste período inicial, geram fissuras, aumentando a permeabilidade das estruturas e podendo induzir problemas de durabilidade e funcionalidade das mesmas. Um detalhado estudo da evolução das tensões durante as primeiras idades pode ser decisivo para manter baixos os níveis de fissuração. Neste trabalho foi implementado um modelo computacional, baseado no método dos elementos finitos, para a simulação do comportamento de peças de concreto nas primeiras idades, tendo, em especial, o propósito de avaliar o potencial risco de fissuração. A análise por elementos finitos abrange a modelagem computacional dos fenômenos químicos, térmicos, de difusão de umidade e mecânicos que ocorrem nos primeiros dias após o lançamento do concreto. Na análise química é determinado o calor gerado pelas reações exotérmicas de hidratação do cimento. Na análise térmica o programa considera ainda o fluxo de calor devido à diferença de temperatura entre o corpo e o ambiente. Em função das propriedades térmicas e geométricas do corpo em estudo são determinadas as temperaturas nodais. Na seqüência, realiza-se a análise de difusão de umidade. Aproveitando a semelhança entre as equações que regem os fenômenos de transferência de calor e difusão de umidade, empregam-se os mesmos procedimentos da análise térmica para a determinação do valor nodal da umidade relativa dos poros. Na análise mecânica, por sua vez, são calculados os estados de tensões decorrentes das variações de temperatura e umidade determinadas nas etapas anteriores e dos fenômenos de retração e fluência do concreto. Quando o estado de tensão de determinado ponto de integração atinge a superfície de ruptura, o ponto passa a ser considerado fissurado. O programa considera a fissuração através de um modelo de fissuras distribuídas com fisssura fixa. Os resultados desta modelagem computacional foram comparados com valores experimentais encontrados na literatura, demonstrando excelente aproximação em todas as etapas de solução implementadas. / The study of the early age properties of concrete is becoming more important, because the thermal effects and the shrinkage, even in the first hours, could generate cracks, increasing the permeability of the structure and being able to induce problems of durability and functionality. The detailed study of the stresses development during the construction process can be decisive to keep low the cracking levels. In this work a computational model, based on the finite element method was implemented, to simulate the early age concrete behavior, having as a special feature, the evaluation of the cracking risk. The finite element analysis encloses the computational modeling of the following phenomena: chemical, thermal, diffusion and mechanical which occur at the first days after the concrete cast. In the chemical analysis, the heat generated by the exothermic reactions of cement hydration is evaluated. In the thermal analysis the program still considers the heat flow due to differences in temperatures between the body and the environment. Considering the thermal and geometric properties of the body, the nodal temperatures are determined. The following analysis is the humidity diffusion. Using the similarity between the equations that describe the phenomena of heat transfer and humidity diffusion, the same thermal analysis procedures are used to evaluate the pore relative humiditys nodal values. In the last analysis, mechanical, the stress states due to temperature and humidity variations, evaluated in the previous steps, and also due to shrinkage and creep are calculated. When the stress state in a determined sample point reaches the rupture surface, the point is considered cracked. The program evaluates cracking through a smeared fixed crack model. The developed software results were compared with experimental values found in the literature, demonstrating an excellent agreement for all the implemented analysis.

The subject of this diploma thesis is to optimize the shield of asynchronous motor. In the thesis are given results of modal and the strain-stress analysis made for model of the shield, which is currently produced. To resolve this issue was used CAE programming system Pro/MECHANICA, which is based on method of geometric elements – GEM. The main output of this work is proposal of two new optimized shields of asynchronous motor and for these are presented results of modal analyse and the strain-stress analysis. Part of the thesis is design and technical-economic evaluation of casting methods for new shield production.

Gegenstand der vorliegenden Publikation sind Festigkeitsberechnungen von Maschinen aus der Hütten- und Walzwerkstechnik mit Pro/Mechanica. Erläutert werden die Arbeitstechniken, die bei der Aufbereitung der Modelle zum Einsatz kommen, sowie die genutzten Regelwerke für den Festigkeitsnachweis. Die angeführten Rechenbeispiele stammen allesamt aus der täglichen Praxis der industriellen Nutzung von FE-Methoden im Maschinenbau.

Zusammenfassung der Neuerungen im Simulationsumfeld von Creo 1.0 (Mechanica/Mechanism/Animation)

- Allgemeine Problematik bei der FEM-Simulation von Lagern/Gelenken - Modellierungstechniken in MECHANICA wie z.B. Kontakt-Analysen, Balkenspinnen, gewichtete Verbindungen, orthotropes Material, etc. - Vergleich dieser Techniken und Diskussion der Vor- und Nachteile anhand eines Gleitlagers - Empfehlungen und Regeln

- ganzheitliche Getriebeauslegung mit Hilfe von Mathcad, Creo™ Elements/Pro™ und MOCAD - Konkretisierung der Problemstellung beim Rundflechten und Ableiten von Bewegungsanforderungen an die Getriebestruktur - Strukturauswahl und Synthese mit Motion-Skelett in Creo™ Elements/Pro™ und Mathcad - MOCAD - MOtion and CAm-Design ist ein universell einsetzbares Werkzeug zum Bewegungsdesign und zur Auslegung von Kurvengetrieben - MOCAD wird zur Bearbeitung von Forschungs- und Industrieprojekten eingesetzt und mit Kooperationspartnern weiterentwickelt - Integrierte FEM-Analyse von Getriebestrukturen und Einzelteilen - Test des neuen Mechanica Features "Gelenkverbindungen"

This thesis deals with construction proposal of front axle consoles for tractor Zetor Forterra. The aim of this work is to design and construct the 3D console model, which will be put through a solidity analysis. Based on this analysis the console will be optimized according to the solidity needs. The model proposal is realized in the software Pro/Engineer. Following strength calculations are realized in the software Pro/Mechanica.

In dieser Präsentation wird das universelle FE-Modell eines Kegelrollenlagers vorgestellt. Mittels eines Pro/ENGINEER-Layouts, basierend auf dem Top-Down Designkonzept, kann automatisch innerhalb einer kurzen Bearbeitungszeit ein geprüftes und lauffähiges FE-Modell eines Kegelrollenlagers abgeleitet werden. Dieses Modell kann z.B. in großen Getriebemodellen eingebaut werden, um eine quasistatische Betrachtung mit korrekten Lagersteifigkeiten zu ermöglichen.

Ermüdungsanalyse mit Pro/Mechanica am Beispiel einer Förderschnecke

Der Vortrag stellt Idee und Grundlagen der Berechnung von Schockantwortspektren dar. Er zeigt, wie man exemplarisch für einen Halbsinusstoß das Schockantwortspektrum in der PTC FEM-Software Creo Elements / Pro Mechanica berechnen kann. Die Schockantworten eines Ein- und Zweimassenschwingers werden sowohl zeitaufgelöst als auch über die dynamische Stoßanalyse berechnet. Die modalen Superpositionsmethoden "Absolute Summe" und "SRSS" (Square Root of the Sum of the Squares - geometrischer Mittelwert) werden vorgestellt. Als reales Beispiel werden Schockanalysen für verschiedene Halbsinusimpulse mit einem Wärmebildgerät der Firma Carl Zeiss Optronics GmbH durchgeführt und mit einer zeitaufgelösten Analyse verglichen. Abschließend wird auf die Erzeugung von Antwortspektren für die Substrukturauslegung eingegangen. / The presentation explains idea and fundamentals of shock response spectra analysis. With help of the PTC FEM-software Creo Elements / Pro Mechanica the shock response spectra (SRS) for an exemplary half sine shock is calculated. The shock response of a one-mass and a two-mass oscillator are analyzed per dynamic time as well as per dynamic shock analysis. The modal superposition methods "absolute sum" and "SRSS" (Square Root of the Sum of the Squares) are explained. The method is applied for different half sine shocks on a realistic example: A thermal imaging system of the company Carl Zeiss Optronics GmbH. Finally, the creation of response spectra for global-local analysis is explained.