Proceedings of the ECCOMAS Thematic Conference on Multibody Dynamics 2015

This volume contains the full papers accepted for presentation at the ECCOMAS Thematic Conference on Multibody Dynamics 2015 held in the Barcelona School of Industrial Engineering, Universitat Politècnica de Catalunya, on June 29 - July 2, 2015. The ECCOMAS Thematic Conference on Multibody Dynamics is an international meeting held once every two years in a European country. Continuing the very successful series of past conferences that have been organized in Lisbon (2003), Madrid (2005), Milan (2007), Warsaw (2009), Brussels (2011) and Zagreb (2013); this edition will once again serve as a meeting point for the international researchers, scientists and experts from academia, research laboratories and industry working in the area of multibody dynamics. Applications are related to many fields of contemporary engineering, such as vehicle and railway systems, aeronautical and space vehicles, robotic manipulators, mechatronic and autonomous systems, smart structures, biomechanical systems and nanotechnologies. The topics of the conference include, but are not restricted to: ● Formulations and Numerical Methods ● Efficient Methods and Real-Time Applications ● Flexible Multibody Dynamics ● Contact Dynamics and Constraints ● Multiphysics and Coupled Problems ● Control and Optimization ● Software Development and Computer Technology ● Aerospace and Maritime Applications ● Biomechanics ● Railroad Vehicle Dynamics ● Road Vehicle Dynamics ● Robotics ● Benchmark ProblemsPostprint (published version

Proceedings of the Fifth NASA/NSF/DOD Workshop on Aerospace Computational Control

The Fifth Annual Workshop on Aerospace Computational Control was one in a series of workshops sponsored by NASA, NSF, and the DOD. The purpose of these workshops is to address computational issues in the analysis, design, and testing of flexible multibody control systems for aerospace applications. The intention in holding these workshops is to bring together users, researchers, and developers of computational tools in aerospace systems (spacecraft, space robotics, aerospace transportation vehicles, etc.) for the purpose of exchanging ideas on the state of the art in computational tools and techniques

Experimental Characterization of the Structural Dynamics and Aero-Structural Sensitivity of a Hawkmoth Wing Toward the Development of Design Rules for Flapping Wing Micro Air Vehicles

A case is made for why the structures discipline must take on a more central role in the research and design of flapping-wing micro-air-vehicles, especially if research trends continue toward bio-inspired, insect-sized flexible wing designs. In making the case, the eigenstructure of the wing emerges as a key structural metric for consideration. But with virtually no structural dynamic data available for actual insect wings, both engineered and computational wing models that have been inspired by biological analogs have no structural truth models to which they can be anchored. An experimental framework is therefore developed herein for performing system identification testing on the wings of insects. This framework is then utilized to characterize the structural dynamics of the forewing of a large sample of hawkmoth (Manduca Sexta) for future design and research consideration. The research also weighs-in on a decade-long debate as to the relative contributions that the inertial and fluid dynamic forces acting on a flapping insect wing have on its deformation (expression) during flight. Ultimately the findings proves that both affect wing expression significantly, casting serious doubt on the longstanding and most frequently cited research that indicates fluid dynamic forces have minimal or negligible effect

GiD 2008. 4th Conference on advances and applications of GiD

The extended use of simulation programs has leaned on the advances in user-friendly interfaces and in the capability to generate meshes for any generic complex geometry. More than ten years of development have made Gid grow to become one of the more popular pre ans postprocessing systems at international level. The constant dialogue between the GiD development team and the users has guided the development of giD to cover the pre-post needs of many disciplines in science and engineering. Following gthis philosophy, the biannual GiD Conference has become an important forum for discussion and interchange of experiences among the GiD community. This monograph includes the contributions of the participants to the fourth edition of the GiD Conference held in the island of Ibiza from 8-9 May 2008

Multibody dynamics 2015

This volume contains the full papers accepted for presentation at the ECCOMAS Thematic Conference on Multibody Dynamics 2015 held in the Barcelona School of Industrial Engineering, Universitat Politècnica de Catalunya, on June 29 - July 2, 2015. The ECCOMAS Thematic Conference on Multibody Dynamics is an international meeting held once every two years in a European country. Continuing the very successful series of past conferences that have been organized in Lisbon (2003), Madrid (2005), Milan (2007), Warsaw (2009), Brussels (2011) and Zagreb (2013); this edition will once again serve as a meeting point for the international researchers, scientists and experts from academia, research laboratories and industry working in the area of multibody dynamics. Applications are related to many fields of contemporary engineering, such as vehicle and railway systems, aeronautical and space vehicles, robotic manipulators, mechatronic and autonomous systems, smart structures, biomechanical systems and nanotechnologies. The topics of the conference include, but are not restricted to: Formulations and Numerical Methods, Efficient Methods and Real-Time Applications, Flexible Multibody Dynamics, Contact Dynamics and Constraints, Multiphysics and Coupled Problems, Control and Optimization, Software Development and Computer Technology, Aerospace and Maritime Applications, Biomechanics, Railroad Vehicle Dynamics, Road Vehicle Dynamics, Robotics, Benchmark Problems. The conference is organized by the Department of Mechanical Engineering of the Universitat Politècnica de Catalunya (UPC) in Barcelona. The organizers would like to thank the authors for submitting their contributions, the keynote lecturers for accepting the invitation and for the quality of their talks, the awards and scientific committees for their support to the organization of the conference, and finally the topic organizers for reviewing all extended abstracts and selecting the awards nominees.Postprint (published version

Τριδιάστατα μη-γραμμικά υβριδικά προσομοιώματα για την ανάλυση μεγάλη κλίμακας κατασκευών από οπλισμένο σκυρόδεμα

308 σ.Αντικείμενο της παρούσας Διατριβής αποτέλεσε η διερεύνηση της μη-γραμμικής συμπεριφοράς κατασκευών οπλισμένου σκυροδέματος με τριδιάστατα υβριδικά προσομοιώματα πεπερασμένων στοιχείων. Η έρευνα αυτή έχει ως σκοπό την ανάπτυξη νέων ή βελτίωση υπαρχουσών μεθόδων προσομοίωσης κατασκευών από οπλισμένο σκυρόδεμα, με σκοπό τον ορθότερο και ασφαλέστερο σχεδιασμό των κατασκευών αυτών. Στα πλαίσια της παρούσας Διατριβής, αναπτύχθηκε ένας κώδικας βασισμένος στις αρχές του εγγενούς αντικειμενοστραφούς προγραμματισμού (ReConAn: Reinforced Concrete Analysis) ο οποίος περιέχει στις βιβλιοθήκες του όλα τα πεπερασμένα στοιχεία και καταστατικούς νόμους υλικών με τους οποίους πραγματεύεται η ερευνητική αυτή εργασία. Τα αποτελέσματα έδειξαν ότι ο νέος κώδικας είναι αρκετά γρήγορος σε σχέση με τα εμπορικά λογισμικά (Femap with NXNastran, Opensees). Επιπρόσθετα, αναπτύχθηκε ένα λογισμικό μετεπεξεργασίας (ReConAn Eye) το οποίο επιτρέπει την αναπαράσταση της ρηγμάτωσης. Ο κώδικας ReConAn, ενσωματώνει προσομοιώματα τριδιάστατων εξαεδρικών πεπερασμένων στοιχείων για τη λεπτομερή προσομοίωση κατασκευών οπλισμένου σκυροδέματος. Παράλληλα, έχει τη δυνατότητα προσομοίωσης του φαινομένου της ρηγμάτωσης μέσω της θεώρησης της μεθόδου της διανεμημένης ρωγμής (smeared crack approach) η οποία συνδυάζεται με τον αλγοριθμικά βελτιωμένο καταστατικό νόμο υλικού σκυροδέματος των Kotsovos & Pavlovic ο οποίος ενσωματώνεται για πρώτη φορά σε τριδιάστατα εξαεδρικά πεπερασμένα στοιχεία 8 κόμβων, γεγονός το οποίο καθιστούν την προτεινόμενη μεθοδολογία προσομοίωσης ταχύτατη. Οι οπλισμοί προσομοιώνονται ως εγκιβωτισμένα στοιχεία δοκού (στοιχείο δυνάμεων ΝΒCFB) τα οποία λαμβάνουν υπόψη την διατμητική και καμπτική στιβαρότητα των ράβδων οπλισμού. Η ακρίβεια των αποτελεσμάτων και η υπολογιστική συμπεριφορά του προτεινόμενου προσομοιώματος συγκρίθηκαν με άλλες μεθοδολογίες προσομοίωσης οι οποίες ενσωματώνονται σε εμπορικά λογισμικά πακέτα που υπάρχουν διεθνώς (ΑΤΕΝΑ, ABAQUS, LS-DYNA, ANSYS). Αναπτύχθηκε μία νέα μεθοδολογία αναγνώρισης εγκιβωτισμένων ραβδωτών στοιχείων οπλισμού εντός εξαεδρικών στοιχείων. Η μέθοδος αυτή επιτρέπει την ελεύθερη τοποθέτηση των οπλισμών εντός των εξαεδρικών στοιχείων και απαιτεί ελάχιστο υπολογιστικό χρόνο για την αναγνώριση και δημιουργία του δικτύου των εγκιβωτισμένων πεπερασμένων στοιχείων οπλισμού. Αναγνωρίστηκε η αδυναμία των λεπτομερών τριδιάστατων προσομοιωμάτων να μοντελοποιήσουν μεγάλης κλίμακας κατασκευές από οπλισμένο σκυρόδεμα λόγω του μεγάλου υπολογιστικού κόστους και αναπτύχθηκε ένα νέο τριδιάστατο μη-γραμμικό υβριδικό προσομοίωμα πεπερασμένων στοιχείων για την ανάλυση κατασκευών από οπλισμένο σκυρόδεμα. Για τον σκοπό αυτό, έγινε η σύνδεση του φυσικού στοιχείου δυνάμεων ΝΒCFB οπλισμένου σκυροδέματος με το εξαεδρικό στοιχείο σκυροδέματος με εγκιβωτισμένες ράβδους. Η λογική διακριτοποίησης μίας κατασκευής με υβριδικό προσομοίωμα, προβλέπει την προσομοίωση των κατασκευαστικών μελών τα οποία αναμένεται να αναπτύξουν σημαντικές μη-γραμμικότητες μέσω τριδιάστατων λεπτομερών προσομοιωμάτων και τα υπόλοιπα κατασκευαστικά μέλη μέσω στοιχείων δοκού-υποστυλώματος.Modeling of RC structures with beam-column type finite elements was proven to be insufficient and inaccurate, especially when dealing with shear dominated structural members and structures with complex geometries. Nevertheless, this type of finite element is used widely for the analysis and design of RC structures due to its computational efficiency which is attributed to the resulting reduced-size numerical finite element models. Based on these limitations, an extensive literature survey was conducted, with the intention to allocate the most promising beam-column FE formulation for modeling RC structures. It was concluded that one of the most numerically advanced beam FE type was the Natural Beam-Column Flexibility-Based (NBCFB) element, which was incorporated in ReConAn software code following an extensive parametric investigation regarding its nonlinear numerical behavior. The second objective of this Dissertation was the literature investigation of 2D and 3D nonlinear modeling methods for RC structures with the purpose of acquiring a general idea about the trends on more sophisticated FE models. Furthermore, the selection of the numerically most promising 3D modeling method was a primary objective, in order to develop a sophisticated software tool capable of predicting the nonlinear response of full-scale RC structures in an acceptable computational time. After this literature review, it was concluded that the existing three-dimensional modeling techniques exhibit a number of limitations for capturing the nonlinear behavior of RC structures and that the corresponding software with sophisticated models for the simulation of nonlinear phenomena, such as cracking and detailed rebar modeling, are very sparse. This is attributed to the numerical restrictions and difficulties described above, whereas the required CPU resources become excessive when dealing with such numerical models even for the case of small-scale FE models. It is well known that the analysis of multistory RC buildings is performed through the use of beam-column elements which allow fast simulation times without serious numerical instabilities. In order to be able to analyze this type of structures with three-dimensional constitutive material models incorporated into 3D finite elements and the use of standard CPU systems, the availability of a powerful software tool is not enough. This constraint derives from the fact that CPU processors are bounded from an upper limit which is determined from the hardware itself. Processing power was not and will never be enough since the demand for the solution of larger numerical models constantly increases. In general, this is attributed to the necessity of large-scale simulations with detailed models for the purpose of capturing, as realistically as possible, the nonlinear behavior of structural systems. Therefore, the third objective of this Dissertation was to determine numerical techniques which will overcome these limitations when dealing with full-scale RC structures. A well-known approach that is used widely in computational mechanics is the use of parallel solvers which in this case will become a subject of future work. A second approach for overcoming this numerical restriction is to use models which combine different types of FE models and which will be called “hybrid models”. This type of modeling assumes that shear dominated structural members with an expected highly nonlinear behavior are modeled with 3D detailed finite elements and the rest of the structure is modeled with simpler beam-column finite elements. This technique leads to a reduction in the complexity of the model and of the required computational demand for the solution of the discretized model, retaining at the same time an acceptable accuracy during the analysis procedure. Finally, the last objective of this research work, was the development of an object-oriented FEA code, capable of easily incorporating advanced numerical techniques and modeling methods for the analysis of RC structures. In addition, it will have the ability to incorporate easily future work and simulation enhancements, which will result into a more general FEA code that will provide the ability of realistic and reliable predictions of the nonlinear response of any type of structure. For the purpose of developing an extendable and sustainable program code, modern programming techniques are used and new numerical methods are developed to create the necessary program structure which will incorporate these state of-the-art features. It is the author’s personal opinion that this task is of great importance, especially when dealing with the solution of computationally complex numerical problems.Γεώργιος Α. Μάρκο

Example Based Caricature Synthesis

The likeness of a caricature to the original face image is an essential and often overlooked part of caricature production. In this paper we present an example based caricature synthesis technique, consisting of shape exaggeration, relationship exaggeration, and optimization for likeness. Rather than relying on a large training set of caricature face pairs, our shape exaggeration step is based on only one or a small number of examples of facial features. The relationship exaggeration step introduces two definitions which facilitate global facial feature synthesis. The first is the T-Shape rule, which describes the relative relationship between the facial elements in an intuitive manner. The second is the so called proportions, which characterizes the facial features in a proportion form. Finally we introduce a similarity metric as the likeness metric based on the Modified Hausdorff Distance (MHD) which allows us to optimize the configuration of facial elements, maximizing likeness while satisfying a number of constraints. The effectiveness of our algorithm is demonstrated with experimental results

Designing sound : procedural audio research based on the book by Andy Farnell

In procedural media, data normally acquired by measuring something, commonly described as sampling, is replaced by a set of computational rules (procedure) that defines the typical structure and/or behaviour of that thing. Here, a general approach to sound as a definable process, rather than a recording, is developed. By analysis of their physical and perceptual qualities, natural objects or processes that produce sound are modelled by digital Sounding Objects for use in arts and entertainments. This Thesis discusses different aspects of Procedural Audio introducing several new approaches and solutions to this emerging field of Sound Design.Em Media Procedimental, os dados os dados normalmente adquiridos através da medição de algo habitualmente designado como amostragem, são substituídos por um conjunto de regras computacionais (procedimento) que definem a estrutura típica, ou comportamento, desse elemento. Neste caso é desenvolvida uma abordagem ao som definível como um procedimento em vez de uma gravação. Através da análise das suas características físicas e perceptuais , objetos naturais ou processos que produzem som, são modelados como objetos sonoros digitais para utilização nas Artes e Entretenimento. Nesta Tese são discutidos diferentes aspectos de Áudio Procedimental, sendo introduzidas várias novas abordagens e soluções para o campo emergente do Design Sonoro

Large space structures and systems in the space station era: A bibliography with indexes

Bibliographies and abstracts are listed for 1372 reports, articles, and other documents introduced into the NASA scientific and technical information system between January 1, 1990 and June 30, 1990. Its purpose is to provide helpful information to the researcher, manager, and designer in technology development and mission design according to system, interactive analysis and design, structural and thermal analysis and design, structural concepts and control systems, electronics, advanced materials, assembly concepts, propulsion, and solar power satellite systems