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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

Parameterstudien und Co-Simulation ebener Koppelgetriebe / Parameter studies and co-simulation of planar linkages

Heinrich, Stefan 07 June 2017 (has links) (PDF)
Im Vortrag geht es um die Erstellung von Berechnungsmodellen zur Simulation ebener Koppelgetriebe in SimulationX. Der Fokus liegt hierbei auf der vollparametrischen Modellsteuerung während der Getriebesynthese in SimulationX. Neben Möglichkeiten zur Steuerung und Variation der Simulationsmodelle während der Berechnung wird die Entwicklung von Berechnungsmodulen zur Individualisierung des Berechnungsprozesses vorgestellt. Möglichkeiten zur Steuerung der Simulation und Co-Simulation bei anderen Programmen ist ebenfalls Thema weiterer Ansätze zur domänenübergreifenden Gesamtsimulation von Koppelgetrieben.
2

Modular Kinematic Analysis Of Planar Linkages

Chowdary, Sekhar V S C 07 1900 (has links)
This thesis has developed an efficient methodology for automatic kinematic analysis of planar linkages using the concept of modular kinematics. Unlike conventional general purpose kinematic analysis packages where each joint in the mechanism is represented using a set of non-linear constraint equations which need to be solved by some iterative numerical procedure, modular kinematics is based on the original observation by Assur that kinematic state of a mechanism involving large number of links can be constructed out of the kinematic states of patterns of sub chains called modules taken in a given sequence called module sequence which in turn emulates the step by step construction procedure of traditional graphical methods. The position, velocity and acceleration analysis of modules are available in closed form. Kinematic analysis of modules later in the sequence is enabled by those of the ones earlier in the sequence, hence, the kinematic analysis of a mechanism is accomplished without any iterative endeavor by doing the kinematics of the modules as given in the module sequence. [102] classified all modules into three fundamental types namely input, dyad and transformation and also introduced the concept of constraint module for analyzing graphically non-constructible mechanisms within the paradigm of modular kinematics where a small step of numerical search was needed in an over all closed form kinematic formulation. Module sequence for a mechanism using the modules is not unique. Choice of a later module in the sequence depends upon the selection of modules earlier in the sequence. This thesis has presented a systematic approach of identifying all such methods for all the inversions of the mechanism and represented in the form of a module hierarchy or a module tree where each path from root to the leaf node represents a valid module sequence for the kinematic chain in hand. The work also extended the set of modules by adding eight new modules to what has already been used in literature to make it complete in the sense that all planar mechanisms involving revolute, prismatic and pin-in-slot (including circular slots) can be handled. The computational effort involved for analyzing these mechanisms thus depend on the number of constraint modules occurring in succession in the module sequence. However, maximum possible number of constraint modules in any mechanism with up to twelve links is only two. The derivative analysis also uses the same module sequence, but they are always devoid of any iterative steps. During the process of generation of a module sequence, at every stage multitude of modules could be identified for their potential placement in the sequence. But for every module sequence the difference between the number of input modules and that of constraint modules is constant and is equal to the kinematic degrees-of-freedom (d.o.f) of the mechanism. The algorithm presented in this thesis minimizes the number of generalized inputs (and hence extraneous constraints) and thus attempting to identify the simplest of the module sequences. In that sense the module sequences represented in the module tree are all optimal module sequences. The present work introduced the concept of multi phase modular kinematics which enables a large variety of mechanisms, conventionally identified as complex mechanisms, to be solved in closed form. This is achieved through the use of novel virtual link and virtual joints. Virtual link is slightly different from a normal rigid link in the sense that the joint locations on this are functions of some independent parameters. Since, the locations of joints are not fixed even in the local coordinate frame of the virtual link, the relative velocities between joints are not zero, they need to be appropriately accounted in kinematic analysis. The theory presented in the thesis is implemented in a computer program written in C++ on Windows platform and Graphics library (OpenGL) is used to display linkage configurations and simulations. The program takes the data of joints, input pairs, ground link in certain format through a file. Geometric models developed in any of the existing modeling softwares like ProE, Ideas, AutoCad etc. can be imported in VRML format to the links and in case of no geometric models a simple convex 2D geometry is created for each link for the purpose of visualization. Geometric import of links helps not only in understanding the simulations better but also in useful for dynamic analysis, dynamic motion analysis and interference analysis. A complete kinematic analysis (position, velocity and acceleration) is given for a four bar mechanism and illustrated the positional ( configuration) analysis using modular kinematics for several other examples like old-ham, quick-return mechanisms etc. in the current work. Multi-phase modular approach is illustrated using a five bar with floating input pairs, a back actor and a drafter mechanism and the Back actor configuration is shown with the imported link geometries. It is observed in practice that there are many apparently spatial Mechanisms, which are constructed out of symmetric dispositions of planar mechanisms in space. A pseudo spatial mechanism concept is proposed to solve this class of spatial mechanisms, which can actually be analyzed with the effort of solving only one such component. This concept is illustrated with Shaker and Umbrella mechanisms. Possible extensions of the concept for modeling and analysis of more general class of pseudo-spatial mechanisms are also indicated.
3

Static Balancing of Rigid-Body Linkages and Compliant Mechanisms

Sangamesh Deepak, R January 2012 (has links) (PDF)
Static balance is the reduction or elimination of the actuating effort in quasi-static motion of a mechanical system by adding non-dissipative force interactions to the system. In recent years, there is increasing recognition that static balancing of elastic forces in compliant mechanisms leads to increased efficiency as well as good force feedback characteristics. The development of insightful and pragmatic design methods for statically balanced compliant mechanisms is the motivation for this work. In our approach, we focus on a class of compliant mechanisms that can be approximated as spring-loaded rigid-link mechanisms. Instead of developing static balancing techniques directly for the compliant mechanisms, we seek analytical balancing techniques for the simplified spring–loaded rigid–link approximations. Towards that, we first provide new static balancing techniques for a spring-loaded four-bar linkage. We also find relations between static balancing parameters of the cognates of a four-bar linkage. Later, we develop a new perfect static balancing method for a general n-degree-of-freedom revolute and spherical jointed rigid-body linkages. This general method distinguishes itself from the known techniques in the following respects: 1 It adds only springs and not any auxiliary bodies. 2 It is applicable to linkage shaving any number of links connected in any manner. 3 It is applicable to both constant(i.e., gravity type) and linear spring loads. 4 It works both in planar and spatial cases. This analytical method is applied on the approximated compliant mechanisms as well. Expectedly, the compliant mechanisms would only be approximately balanced. We study the effectiveness of this approximate balance through simulations and a prototype. The analytical static balancing technique for rigid-body linkages and the study of its application to approximated compliant mechanisms are among the main contributions of this thesis.
4

Parameterstudien und Co-Simulation ebener Koppelgetriebe

Heinrich, Stefan 07 June 2017 (has links)
Im Vortrag geht es um die Erstellung von Berechnungsmodellen zur Simulation ebener Koppelgetriebe in SimulationX. Der Fokus liegt hierbei auf der vollparametrischen Modellsteuerung während der Getriebesynthese in SimulationX. Neben Möglichkeiten zur Steuerung und Variation der Simulationsmodelle während der Berechnung wird die Entwicklung von Berechnungsmodulen zur Individualisierung des Berechnungsprozesses vorgestellt. Möglichkeiten zur Steuerung der Simulation und Co-Simulation bei anderen Programmen ist ebenfalls Thema weiterer Ansätze zur domänenübergreifenden Gesamtsimulation von Koppelgetrieben.
5

New concept of continuously interactive analysis-synthesis-parameter-adjustments (ASPA) for nonlinear drive assemblies

Heinrich, Stefan, Berger, Maik 29 June 2018 (has links)
Dieser Beitrag zeigt, dass sich neue Möglichkeiten und Entwicklungsfelder beim Einsatz der domänenübergreifenden Simulationsumgebung SimulationX in der Getriebesynthese ergeben. Der Ansatz, jegliche nichtlineare Bewegungsaufgaben mathematisch in Form von Unterstützungsmodulen in einer Programmoberfläche zu komplexen Modellen zu verbinden, ermöglicht nun auch die Umsetzung einer ganzheitlichen Getriebesynthese mit einem kontinuierlichen Analyse-Synthese-Parameter-Abgleich (ASPA). Der Anwender kann somit in nur einer Programmoberfläche sowohl Mechanismen-Synthese als auch -Analyse durchführen und beispielsweise durch entsprechende Optimierung den getriebedynamisch günstigsten Mechanismus ermitteln. / This report shows that new opportunities and areas of development arise from using the domain spanning system simulation software SimulationX for the analysis and synthesis of nonlinear mechanisms. The idea to mathematically combine arbitrary motion demands to complex models in the form of support modules within a unique program interface now allows for a holistic mechanism synthesis with a continuous analysis-synthesis-parameter-adjustment (ASPA). Hence, the user may perform both mechanism analysis and synthesis employing one single program interface (e.g. to identify the ideal mechanism in terms of dynamics during an optimization process).
6

Module based synthesis of a 14 bar deep drawing press considering kinetic criteria

Heinrich, Stefan, Berger, Maik 30 March 2019 (has links)
Die Entwicklung ebener Koppelgetriebe als nichtlinear übersetzende Antriebe in Verarbeitungsmaschinen stellt bis heute ein domänenübergreifendes Fachgebiet des Maschinenbaus dar. Auf der einen Seite gilt es, die Koppelgetriebe möglichst effizient in einer sich stetig wandelnden Softwarelandschaft zu synthetisieren (geometrische Maßfindung der Getriebeglieder) und auf der anderen Seite steigen die mechanischen Anforderungen. Aus diesem Grund besteht der Wunsch nach einer Vereinigung von Synthese und Analyse (kinematisch sowie kinetisch) in möglichst einer Programmumgebung. Basierend auf dem zum 18. ITI Symposium im Jahr 2015 vorgestellten modulbasierten Analyse-Synthese-Parameter-Abgleich (ASPA) ist in den vergangenen Jahren eine umfangreiche Bibliothek zur modulbasierten Synthese ebener Koppelgetriebe in SimulationX entstanden. Der Beitrag zeigt am Beispiel eines 14-gliedrigen Pressenantriebes, welche neuen Möglichkeiten im Kontext von ASPA innerhalb von SimulationX durch diese Bibliothek entstanden sind. Basierend auf vorausgegangenen Arbeiten wurde erstmals die Möglichkeit der Synthese des Getriebes mittels Maßsynthese bei einer gleichzeitigen Beeinflussung der Gelenkkräfte und Bewegungsverläufe nachgewiesen. Dabei kam der Variantenassistent in SimulationX für die Ermittlung der Parametersensitivitäten zum Einsatz. Das Einbinden von parametrisierten Trägheitskenngrößen auf Basis vereinfachter Volumenkörper ermöglichte hierbei die Berücksichtigung der Bauteilmassen während der Synthese. Die Möglichkeit der gleichzeitigen Beurteilung kinematischer und kinetischer Kenngrößen während der Synthese ist an dieser Stelle ein besonderes Merkmal des Konzeptes ASPA. / Developing nonlinear transmitting planar coupler linkages represents a domain enclosing field in mechanical engineering. On the one hand, there is a demand for an efficient layer synthesis (geometrical sizing of the links) and on the other hand, it is necessary to adapt to a constantly changing software environment. Thus, it is desired to crosslink the kinematical and kinetical synthesis and analysis of linkages within one software environment. Based on a paper about the Analysis-Synthesis-Parameter-Adjustment (ASPA), published at the 18th ITI Symposium in 2015, an extensive synthesis library has been developed in SimulationX. By the example of a 14 bar deep drawing press this paper reveals new opportunities that arise from the application of ASPA on the basis of the new library in SimulationX. Compared to prior papers on this particular press this paper, for the first time, presents a complete layer synthesis of this linkage regarding kinetic boundary conditions. In order to meet conditions, such as motion demands and joint forces, parameter sensitivities have been determined by applying the variants-wizard in SimulationX. Using parameterized mass properties on the basis of simplified solids has allowed the specification of link masses during the synthesis. The opportunity of simultaneously taking kinematic and kinetic characteristics during the layer synthesis into account defines the concept of ASPA.
7

Modulbasierte Synthese ebener Koppelgetriebe unter Einbeziehung kinetischer Kenngrößen

Heinrich, Stefan 07 November 2018 (has links)
Die Entwicklung mechanischer Antriebskonzepte für nichtlineare Bewegungsaufgaben stellt bis heute ein komplexes und domänenübergreifendes Fachgebiet des Maschinenbaus dar. Auf dem Gebiet der ebenen Koppelgetriebe gibt es dabei seit vielen Jahren Versuche, die optimale Lösung für eine Aufgabe unter Berücksichtigung kinetischer Kenngrößen zu finden. Die vorliegende Arbeit stellt eine Methodik vor, die sowohl den klassischen Verfahren der Getriebetechnik als auch den Ansätzen der Mechanik zum Ausgleich der Massenwirkungen im Getriebe gerecht wird. Der entwickelte Ansatz des modulbasierten Analyse-Synthese-Parameter-Abgleiches (ASPA) erlaubt erstmals eine domänenübergreifende Simulation komplexer Antriebskonzepte auf Basis einer neuartigen modularen Synthesebibliothek. Diese lässt sich dank umfangreicher Dokumentation und der dargestellten Programmablaufpläne in beliebige Software implementieren. Die exemplarisch im Systemsimulator SimulationX implementierte Bibliothek ermöglicht somit unter anderem die Anwendung der klassischen Drei- und Vierlagensynthese im bewegten oder ruhenden Bezugssystem für Dreh- und Schubgelenkketten. Neben der Ausgabe gerundeter Getriebeabmessungen eröffnet der beschriebene Ansatz somit die Berücksichtigung kinetischer Kenngrößen wie den Pendelschwingungen in spielbehafteten Gelenken oder der Änderung der Trägheitskenngrößen während der Synthese. Weiterführend kann eine multikriterielle Optimierung der noch freien Syntheseparameter erfolgen. / Developing nonlinear transmitting planar coupler linkages represents a domain spanning area in mechanical engineering. In recent years many efforts have been made to determine the optimal planar linkage regarding kinetic characteristics. This thesis introduces a method linking classical synthesis procedures with mechanical approaches for a dynamically balanced mechanism. For the first time, the module based analysis-synthesis-parameter-adjustment (ASPA) allows for a domain spanning simulation of complex drive assemblies based on a novel modular synthesis library. Due to an extensive documentation and detailed program flow charts it is possible to implement the library in arbitrary software environments. The exemplarily implemented library in SimulationX allows to apply the classical three- and four-position synthesis within a steady or moving reference frame of revolute or prismatic joint chains. Further, the modules return rounded link dimensions. By applying this library according to ASPA it is now possible to account for kinetic boundaries such as pendulum oscillations of joints with joint clearance or the change of mass properties during the position synthesis. Thus, a multi-criteria optimization of the remaining free synthesis parameters can be applied.

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