Effects of Energy Dissipation on the Free Body Motions of Spacecraft

Modal model using deformation modes of slightly flexible, lightly damped structure to analyze effects of energy dissipation on free body motions of spacecraf

NASA patent abstracts bibliography: A continuing bibliography. Section 1: Abstracts (supplement 07)

This bibliography is issued in two sections: Section 1 - Abstracts, and Section 2 - Indexes. This issue of the Abstract Section cites 158 patents and applications for patent introduced into the NASA scientific and technical information system during the period of January 1975 through June 1975. Each entry in the Abstract Section consists of a citation, an abstract, and, in most cases, a key illustration selected from the patent or application for patent. This issue of the Index Section contains entries for 2830 patent and application for patent citations covering the period May 1969 through June 1975. The index section contains five indexes -- subject, inventor, source, number and accession number

The ground deformations: tools, methods and application to some Italian volcanic regions

2010 - 2011The objective of this thesis is the study of slow deformation of the soil as a result of intrusion of magma inside the magmatic chambers of some volcanoes located in Southern Italy. In particular, the Mt. Vesuvius and Campi Flegrei caldera have been monitored over the last 7 years. The research has been accomplished through the use of geodetic instrumentation (long baseline tiltmeters, Sacks-Evertson dilatometers) that has been installed during the entire period of the research near the aforementioned volcanoes. The data were recorded with the aid of data-logger, some of which are specifically designed for the current research. Campi Flegrei and Mt. Vesuvius are two volcanoes located near Naples, already monitored by Osservatorio Vesuviano, the local office of INGV (Istituto Nazionale di Geofisica e Vulcanologia). In the last 40 years systematic recordings of seismic data, of changes in distance of milestones, of leveling lines, of local gravimetric anomalies and of GPS-InSAR data have been carried out. Starting from 2004, the monitoring network maintained by Osservatorio Vesuviano has been enriched by the DINEV project: this is intended as a complementary network of geodetic stations and consists in the installation of a small array of 6 borehole stations (with an average depth of 120 m), each of which is constituted by a three components borehole broadband seismometer Teledyne Geotech KS2000BH and a Sacks-Evertson areal strainmeter (dilatometer). In addition, two three components surface broadband seismometers Guralp CMG 3-ESP have been installed to control the anthropogenic surface noise. In Campi Flegrei caldera, then, another array of instruments has been installed: two long baseline water tiltmeters have been installed in Italian Army abandoned tunnels. The total length of tiltmeters is about 350 m for the northernmost tunnel, and of about 150 m for the southernmost tunnel. Tiltmeters were installed, respectively, in axial and tangential direction in respect with the position of the Campi Flegrei magmatic chamber. The use of the instruments described in the current report allows to model the strain field in the range of low frequencies, monitoring the deformation tensor for its non-diagonal components (pure tilt) by using the tiltmeters, and the diagonal components (pure deformation) by using the dilatometers. The monitoring is occurred for a time range of some years in length, needed to remove the seasonal drifts due to changes in rainfalls, while the deformation due to changes in barometric pressure have been deleted using linear regression techniques. [edited by author]X n.s

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

Computational methods and software systems for dynamics and control of large space structures

Two key areas of crucial importance to the computer-based simulation of large space structures are discussed. The first area involves multibody dynamics (MBD) of flexible space structures, with applications directed to deployment, construction, and maneuvering. The second area deals with advanced software systems, with emphasis on parallel processing. The latest research thrust in the second area involves massively parallel computers

Англійська мова для студентів електромеханічних спеціальностей

Навчальний посібник розрахований на студентів напряму підготовки 6.050702 Електромеханіка. Містить уроки, що структуровані за тематичними розділами, граматичний коментар, короткі англо-український і українсько- англійський словники та додатки, які спрямовані на закріплення загальних навичок володіння англійською мовою. Акцентований на ɨсобливості термінології, що застосовується у науково-технічній галузі, зокрема, в електромеханіці та виконання запропонованих завдань, що буде сприяти формуванню навичок перекладу з англійської та української мов, сприйняттю письмової та усної англійської мови, вмінню письмового викладення англійською мовою науково-технічних та інших текстів під час професійної діяльності, спілкуванню з професійних та загальних питань тощо

Mathematical and Numerical Aspects of Dynamical System Analysis

From Preface: This is the fourteenth time when the conference “Dynamical Systems: Theory and Applications” gathers a numerous group of outstanding scientists and engineers, who deal with widely understood problems of theoretical and applied dynamics. Organization of the conference would not have been possible without a great effort of the staff of the Department of Automation, Biomechanics and Mechatronics. The patronage over the conference has been taken by the Committee of Mechanics of the Polish Academy of Sciences and Ministry of Science and Higher Education of Poland. It is a great pleasure that our invitation has been accepted by recording in the history of our conference number of people, including good colleagues and friends as well as a large group of researchers and scientists, who decided to participate in the conference for the first time. With proud and satisfaction we welcomed over 180 persons from 31 countries all over the world. They decided to share the results of their research and many years experiences in a discipline of dynamical systems by submitting many very interesting papers. This year, the DSTA Conference Proceedings were split into three volumes entitled “Dynamical Systems” with respective subtitles: Vibration, Control and Stability of Dynamical Systems; Mathematical and Numerical Aspects of Dynamical System Analysis and Engineering Dynamics and Life Sciences. Additionally, there will be also published two volumes of Springer Proceedings in Mathematics and Statistics entitled “Dynamical Systems in Theoretical Perspective” and “Dynamical Systems in Applications”

Robuste Berechnungsverfahren zur nichtlinearen dynamischen Analyse von Balken- und Schalenstrukturen

Gegenwärtige und zukünftige dynamisch beanspruchte, schlanke Strukturen aus mehrschichtig verbundenen, hyperelastischen Werkstoffen, z. B. Windenergieanlagen und Hubschrauber usw., sind sehr komplex. Eine genaue Untersuchung im Zeitbereich erfordert den Einsatz von Methoden, die kinematische, geometrische sowie, bis zu einem gewissen Grad, materielle Nichtlinearitäten berücksichtigen sollten. Daher könnten Simulationen mit Beachtung von großen Verschiebungen, Drehungen und Verzerrungen nötig sein, um das mechanische Verhalten akkurat zu vorhersagen zu vermögen. Zunächst werden die Bewegungsgleichungen räumlich diskretisiert. Dann werden die zum Teil diskretisierten Gleichungen mittels eines Integrationsverfahrens zeitlich diskretisiert. Solche diskreten Gleichungen sind sehr steif, sodass sich die Berechnung der langzeitigen Lösung erschwert. Darüber hinaus ist die Einführung von Nebenbedingungen oft nötig, um komplexere Strukturen aufstellen zu können, wodurch sich die Komplexität erhöht wird und unerwünschte Eigenschaften noch verschärft werden. Um Robustheit zu gewinnen, sollen Berechnungsverfahren hergeleitet werden, die die zugrunde legende Physik in gewissem Maße erhalten können und gleichzeitig den hochfrequenten Anteil der Lösung unterdrücken können. Die Erfüllung dieser Anforderungen stellt sich als sehr herausfordernd dar. Das Hauptziel dieser Arbeit liegt an der Entwicklung von Berechnungsverfahren zur Vertiefung des Verständnises des dynamischen Verhaltens von Balken- und Schalenstrukturen. Um dieses Ziel zu erreichen, wird ein umfassender Ansatz vorgeschlagen. Dieser besteht aus: i) Einer auf Direktoren basierenden, Finite-Elemente-Formulierung für den geometrisch exakten Balken mit allgemeinen Querschnittseigenschaften; ii) einer auf Direktoren basierenden, Finite-Elemente-Formulierung für die Kontinuumsmechanik-basierte Schale aus mehrschichtig verbundenen, hyperelastischen Werkstoffen; iii) einer vereinheitlichten Beschreibung von Starrkörpern, Balken und Schalen und deren Kopplung mittels kinematischer Nebenbedingungen; und, iv) einem robusten Integrationsverfahren basierend auf dem gemittelten Vektorfeld. Des Weiteren wird Folgendes ebenfalls vorgeschlagen: v) Die Partikularisierung der Hauptgeodätenanalyse zur nichtlinearen Identifikation von Bewegungsmoden an Balkenstrukturen; und, vi) ein neues konservatives/dissipatives Integrationsverfahren für allgemeine nichtlineare mechanische Systeme basierend auf optimierten Modifizierungen höherer Ordnung, die die Defizite der Mittelpunktsregel beheben. Die sehr gute Leistung des vorgeschlagenen Ansatzes wird durch mehrere Beispiele unterschiedlicher Komplexität nachgewiesen.Existing and new slender structures made of hyperelastic multilayer composite materials subject to highly dynamic loads, e.g., wind turbines, helicopters, cars, speedboats or submarines inter alia, are very complex. Their dynamic analysis requires fully nonlinear formulations, at least from the kinematic and geometric point of view, and also to some extent from the material point of view. Thus, simulations in time-domain involving large displacements, rotations and strains could be necessary to predict their mechanical behavior accurately. Numerical procedures to carry out such simulations rely firstly on the partial discretization in space of the governing equations, for instance with finite elements. These semi discrete equations are further discretized in time with an integration scheme. The resulting discrete equations are in fact very stiff and therefore, the computation of the long-term behavior could be problematic. In many applications, the introduction of constraints is also necessary for rendering more complex structures. Besides introducing a new level of complexity, this can sharpen conditioning problems already present in the fully discrete problem. Additionally, we also require procedures able to annihilate the unwanted unresolved high-frequency content without upsetting of the underlying physics. However, the simultaneous satisfaction of all these requirements is a very challenging task. The main objective of this work is to provide means intended for helping to understand further the nonlinear dynamics of beam and shell structures made of hyperelastic multilayer composite materials subject to highly dynamic loads. To accomplish this main goal, we propose a unifying computational approach that relies on: i) a director-based finite-element formulation for geometrically exact beams with general cross-section properties; ii) a director-based finite-element formulation for solid-degenerate shells made of hyperelastic multilayer composite materials; iii) a unifying description of rigid bodies, geometrically exact beams and solid-degenerate shells and their combination with kinematic pairs, which avoids inherently the necessity of rotational degrees of freedom; and, iv) a robust integration scheme based on the average vector field. Additionally, we propose: v) the particularization of the principal geodesic analysis to identify motion patters exhibited by beam structures in a purely nonlinear setting; and, vi) a new conservative/dissipative integration method for general nonlinear mechanical systems, which relies on high-order correction terms that optimally modify the midpoint rule. Moreover, the excellent numerical performance of the proposed unifying framework and procedures is illustrated by means of a good number of examples with different difficulty levels

A computational procedure for the dynamics of flexible beams within multibody systems

The dynamic analysis of three dimensional elastic beams which experience large rotational and large deformational motions are examined. The beam motion is modeled using an inertial reference for the translational displacements and a body-fixed reference for the rotational quantities. Finite strain rod theories are then defined in conjunction with the beam kinematic description which accounts for the effects of stretching, bending, torsion, and transverse shear deformations. A convected coordinate representation of the Cauchy stress tensor and a conjugate strain definition is introduced to model the beam deformation. To treat the beam dynamics, a two-stage modification of the central difference algorithm is presented to integrate the translational coordinates and the angular velocity vector. The angular orientation is then obtained from the application of an implicit integration algorithm to the Euler parameter/angular velocity kinematical relation. The combined developments of the objective internal force computation with the dynamic solution procedures result in the computational preservation of total energy for undamped systems. The present methodology is also extended to model the dynamics of deployment/retrieval of the flexible members. A moving spatial grid corresponding to the configuration of a deployed rigid beam is employed as a reference for the dynamic variables. A transient integration scheme which accurately accounts for the deforming spatial grid is derived from a space-time finite element discretization of a Hamiltonian variational statement. The computational results of this general deforming finite element beam formulation are compared to reported results for a planar inverse-spaghetti problem