DOCSLIB.ORG

Advances in Shake Table Control and Substructure

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Advances in Shake Table Control and Substructure ADVANCES IN SHAKE TABLE CONTROL AND SUBSTRUCTURE SHAKE TABLE TESTING by Matthew Joseph James Stehman A dissertation submitted to The Johns Hopkins University in conformity with the requirements for the degree of Doctor of Philosophy. Baltimore, Maryland June, 2014 c Matthew Joseph James Stehman 2014 All rights reserved Abstract Shake table tests provide a true representation of seismic phenomena including a fully dynamic environment with base excitation of the test structure. For this rea- son shake tables have become a staple in many earthquake engineering laboratories. While shake tables are widely used for research and commercial applications, further developments in shake table techniques will allow researchers to use shake tables in a broader range of studies. This dissertation presents recent advances in the use of shake tables for the seismic performance evaluation of civil engineering structures. Develop- ments include theoretical and experimental investigations of substructure shake table testing, a technique where the entire test structure is separated into computational and experimental substructures. Challenges in meeting the boundary conditions be- tween the substructures have limited the number of implementations of substructure shake table testing to date; thus in this dissertation, appropriate methods of address- ing the boundary conditions between experimental and computational substructures are presented and evaluated. Also, a novel strategy for acceleration control of shake tables is presented to enhance the acceleration tracking performance of shake tables ii ABSTRACT to be used in substructure shake table testing. Results are presented that show the promise in using the developed techniques over traditional shake table testing meth- ods. Primary Reader: Narutoshi Nakata Secondary Readers: Benjamin Schafer and Judith Mitrani-Reiser iii Acknowledgments I would like to sincerely thank my advisor, Professor Narutoshi Nakata, for all of his helpful advice and mentoring during my time at Johns Hopkins. I would also like to thank my colleagues John Hinchcliffe and Richard Erb, for helping me design and build the test setups necessary for the experimental part of my research. I would like to extend a special thanks to Nick Logvinovsky for always helping me find the right tool for the job. Finally, I would like to acknowledge the National Science Foundation for their financial support. The research presented in this dissertation was fully supported by the grant entitled \CAREER: Advanced Acceleration Control Methods and Sub- structure Techniques for Shaking Table Tests (grant no. CMMI- 0954958)". iv Dedication To my family, for all the support and encouragement they have given me. v Contents Abstract ii Acknowledgments iv List of Tables xi List of Figures xii 1 Introduction 1 1.1 Literature Review . 2 1.1.1 Shake Table Testing . 3 1.1.2 Real-Time Hybrid Simulation . 7 1.1.3 Substructure Shake Table Testing . 10 1.2 Overview of Dissertation . 13 2 Shake Table Dynamics 15 2.1 Dynamics of Shake Tables with Hydraulic Actuators . 16 vi CONTENTS 2.2 Acceleration Relationships . 21 2.3 Summary and Discussion . 23 3 Substructure Shake Table Testing of Upper Stories in Tall Buildings 24 3.1 Formulation . 25 3.1.1 Equations of Motion . 25 3.1.2 Compatibility Requirements . 27 3.1.3 Concept of Substructure Shake Table Testing . 29 3.2 Experimental Setup and Modeling . 30 3.2.1 Uni-Axial Shake Table . 30 3.2.2 Control and Data Acquisition System . 31 3.2.3 Experimental Substructure . 32 3.2.4 Computational Substructure . 33 3.2.5 Measurement of Base Shear . 34 3.3 Acceleration Control Performance . 35 3.3.1 Issues of Acceleration Control and Control-Structure-Interaction 35 3.3.2 Propagation of Input Acceleration Errors . 38 3.4 Substructure Shake Table Test System with Error Compensation . 39 3.4.1 Numerical Integration for the Computational Substructure . 40 3.4.2 State Observer and Kalman Filter . 42 3.4.3 Model-Based Actuator Delay Compensation . 44 vii CONTENTS 3.4.4 Corrector for Errors in Base Shear Induced by Input Accelera- tion Errors . 46 3.5 Experimental Results . 47 3.5.1 Harmonic Ground Excitation Inputs . 48 3.5.2 Earthquake Ground Excitation Input . 54 3.6 Advanced Model-Based Shake Table Compensation Techniques . 58 3.6.1 Feedforward Compensation using Derivatives of Reference Signal 58 3.6.2 IIR Compensation Technique for Significant Control-Structure- Interaction . 60 3.6.3 Experimental Investigation of Model-Based Delay Compensa- tion Techniques . 62 3.7 Summary and Discussion . 69 4 Substructure Shake Table Testing of Lower Stories in Tall Buildings 71 4.1 Interface Compatibility using a Controlled Mass . 72 4.1.1 Simulation Models . 78 4.1.2 Numerical Investigation . 81 4.2 Interface Compatibility using a Force Controlled Actuator . 91 4.2.1 Actuator Control Scheme . 91 4.2.2 Numerical Case Study . 95 4.3 Summary and Discussion . 101 viii CONTENTS 5 Acceleration Feedback Control of Shake Tables 102 5.1 Acceleration Feedback Control with Force Stabilization . 103 5.1.1 Control Architecture . 103 5.1.2 Hardware Requirements . 105 5.2 Experimental Setup . 107 5.3 Experimental Investigation of the Proposed Acceleration Control Strat- egy . 108 5.3.1 Experimental Modeling of the Shake Table System . 110 5.3.2 Design of the Feedback Controllers and Pre-Gains . 112 5.3.3 Experimental Validation of the Proposed Acceleration Control Strategy . 116 5.4 Impact of Input Acceleration Errors in Shake Table Tests on Structural Response . 120 5.5 Summary and Discussion . 123 6 Conclusions and Future Work 125 6.1 Conclusions . 125 6.2 Future Work . 127 6.2.1 Near Term . 127 6.2.2 Long Term . 129 Appendix A 131 ix CONTENTS References 133 Vita 142 x List of Tables 3.1 Dynamic properties of the entire 10-story RTHS structure . 34 3.2 Summary of shake table performance from substructure shake table testing using 3 different compensation techniques. 66 4.1 Properties and dynamic characteristics of the 5-story structure. 79 4.2 RMS differences for simulation responses under different earthquake simulations. 86 5.1 Dynamic characteristics of three story test structure. 108 5.2 Analytical representations of the open loop shake table dynamics. 112 5.3 Errors between measured and reference shake table accelerations. 120 5.4 Errors between measured and reference top floor structural accelerations.123 xi List of Figures 1.1 Schematic of a early stage hand powered shake table, CREDIT: Severn (2011). 4 1.2 Schematic of the E-Defense shake table system, CREDIT: Ogawa et al. (2001). 4 1.3 Early implementation of pseudo-dynamic testing, CREDIT: Nakashima et al. (1992). 9 1.4 Implementation of RTHS where the experimental substructure is a single damper, CREDIT: Carrion et al. (2009). 9 1.5 Concept of substructure shake table testing including a tuned mass damper, CREDIT: Igarashi et al. (2000). 11 2.1 Schematic of a uni-axial shake table with linear structure. 16 2.2 Block diagram of shake table system including hydraulic actuator, test structure and feedback controller. 19 3.1 Schematics of substructure shake table testing in comparison with the entire simulation. 26 3.2 A block diagram for the concept of substructure shake table testing. 30 3.3 A three-story steel frame structure on the uni-axial shake table at Johns Hopkins University. 31 3.4 Frequency response curves of the three-story steel experimental sub- structure. 33 3.5 Frequency response curves of closed-loop (reference to measured) dis- placement and acceleration: (a) displacement magnitude; (b) acceler- ation magnitude; (c) displacement phase; and (d) acceleration phase. 37 3.6 Frequency response curve and coherence from the table acceleration to measured base shear. 39 3.7 A block diagram of the substructure shake table test system with com- pensation techniques for experimental errors. 40 xii LIST OF FIGURES 3.8 Acceleration and base shear time histories under 2.0 Hz harmonic ground excitation: (a) the entire acceleration time histories; (b) a zoomed section of the acceleration time histories; (c) the entire base shear time histories; and (d) a zoomed section of the base shear time histories. 48 3.9 Structural responses under 2.0 Hz harmonic ground excitation: (a), (d), and (g), relative floor displacement at the 10th, 6th and 2nd floor, respectively; (b), (e), and (h), absolute floor displacement at the 10th, 6th and 2nd floor, respectively; and (c), (f), and (i), absolute floor acceleration at the 10th, 6th and 2nd floor, respectively. 51 3.10 Acceleration and base shear time histories under 6.0 Hz harmonic ground excitation: (a) the entire acceleration time histories; (b) a zoomed section of the acceleration time histories; (c) the entire base shear time histories; and (d) a zoomed section of the base shear time histories. 52 3.11 Structural responses under 6.0 Hz harmonic ground excitation: (a), (d), and (g), relative floor displacement at the 10th, 6th and 2nd floor, respectively; (b), (e), and (h), absolute floor displacement at the 10th, 6th and 2nd floor, respectively; and (c), (f), and (i), absolute floor acceleration at the 10th, 6th and 2nd floor, respectively. 54 3.12 Acceleration and base shear time histories under the 1995 Kobe earth- quake excitation: (a) the entire acceleration time histories; (b) a zoomed section of the acceleration time histories; (c) the entire base shear time histories; and (d) a zoomed section of the base shear time histories. 55 3.13 Structural responses under the 1995 Kobe earthquake excitation: (a), (d), (g), (j), and (m), relative displacement at the even floors from top to bottom (10th to 2nd); (b), (e), (h), (k), and (n), absolute displace- ment at the even floors from top to bottom (10th to 2nd); and (c), (f), (i), (l), and (o), absolute displacement at the even floors from top to bottom (10th to 2nd)...........................
Load more

Recommended publications
  • Structural Analysis
    Structural Analysis Structural Analysis Photo courtesy of Institute of Dynamics and Vibration Research, Leibniz Universität Hannover, Germany Leibniz Universität Hannover, Research, Photo courtesy of Institute Dynamics and Vibration m+p Analyzer’s structural analysis package provides • Multiple Degree of Freedom (MDOF) analysis a complete set of tools for observing, analyzing and • Circle fit wizard to review and validate FRF data and documenting the vibrational behaviour of machines and mode shapes mechanical structures. Different software modules cover a • Operational modal analysis (OMA) wide range of techniques including impact testing, shaker • Modal model validation (MAC, MPD, MPC, MOV, MIF) measurements (SIMO and MIMO), experimental and • Polyreference Time Domain algorithm (PTD/PolyTime) operational modal analysis, ground vibration testing, • Polyreference Time Domain Plus algorithm (PTD+/ operating deflection shape analysis, and modal model Polytime+) validation. • Polyreference Least-Squares Complex Frequency domain algorithm (p-LSCF/Polyfreq) The standard structural dynamics package includes: • Multiple Input/Multiple Output (MIMO) analysis including • Impact testing using a modal hammer multi-source outputs • Creation of component-based geometries • Swept and stepped sine analysis • Operating Deflection Shape (ODS) analysis • Ground vibration testing (GVT) with Normal Mode Optional software modules are available to cover the most Tuning (NMT) demanding and advanced modal analysis applications: • Interface to FEMtools for Structural
    [Show full text]
  • Nonlinear Dynamics in Mechanics and Engineering: 40 Years of Developments and Ali H
    This is a post-peer-review, pre-copyedit version of the paper Nonlinear dynamics in mechanics and engineering: 40 years of developments and Ali H. Nayfeh’s legacy by Giuseppe Rega Department of Structural and Geotechnical Engineering, Sapienza University of Rome, Italy Please cite this work as follows: Rega, G., Nonlinear dynamics in mechanics and engineering: 40 years of developments and Ali H. Nayfeh’s legacy, Nonlinear Dynamics, 99(1), 11-34, 2020, DOI: 10.1007/s11071-019-04833-w. Publisher link and Copyright information: You can download the final authenticated version of the paper from: http://dx.doi.org/10.1007/s11071-019-04833-w. © 2020 Springer Nature Switzerland AG This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License. To view a copy of this license, visit http://creativecommons.org/licenses/by- nc-nd/4.0/ or send a letter to Creative Commons, PO Box 1866, Mountain View, CA 94042, USA. Licensees may copy, distribute, display and perform the work and make derivative works and remixes based on it only if they give the author or licensor the credits (attribution) in the manner specified by these. Licensees may copy, distribute, display, and perform the work and make derivative works and remixes based on it only for non-commercial purposes. Licensees may copy, distribute, display and perform only verbatim copies of the work, not derivative works and remixes based on it. Nonlinear Dynamics in Mechanics and Engineering: Forty Years of Developments and Ali H. Nayfeh’s Legacy Giuseppe Rega Department of Structural and Geotechnical Engineering, Sapienza University of Rome, Italy e-mail: [email protected] Abstract: Nonlinear dynamics of engineering systems has reached the stage of full maturity in which it makes sense to critically revisit its past and present in order to establish an historical perspective of reference and to identify novel objectives to be pursued.
    [Show full text]
  • Structural Vibration and Ways to Avoid It
    Structural Vibration and Ways to Avoid It Dynamic loadings take many forms. Two parameters can characterize such loadings: Their magnitude and their frequency content. Dynamic loadings can be replaced by static loadings when their frequency content is low compared to the natural frequency of the structure on which they are applied. Some people will refer as quasi-static analysis or loadings to remind themselves that they are actually predicting the effect of dynamic loadings treated as static equivalent. Most environmental loads (winds, earthquake, wave, transportation) can be replaced by quasi-static equivalents. When the frequency content of a dynamic loading and the natural frequencies of a structure are in the same range, then this approximation is no longer valid. This is the case for most machinery (compressors, pumps, engines, etc.) which produce loadings whose frequency content overlaps the natural frequencies of the structure on which they are mounted (platform, FPSO, etc.). In such a case, only a dynamic analysis will accurately predict the amplification of the response of the structure. Such loadings cannot be replaced by quasi-static equivalents. What makes these analyses even more challenging is the fact that the machinery, its equipment and the mounting skid cannot be seen as black boxes. They will interact with the foundation, the platform or the FPSO and the only way to know the magnitude of this interaction is to conduct a structural dynamic analysis that includes the foundation. This is a critical consideration which when overlooked considerably reduces the reliability of the machine and might even cause safety concerns. Structural Vibration and Resonance Structural vibration occurs when dynamic forces generated by compressors, pumps, and engines cause the deck beams to vibrate.
    [Show full text]
  • STRUCTURAL DYNAMICS Theory and Computation Fifth Edition STRUCTURAL DYNAMICS Theory and Computation Fifth Edition
    STRUCTURAL DYNAMICS Theory and Computation Fifth Edition STRUCTURAL DYNAMICS Theory and Computation Fifth Edition Mario Paz Speed Scientific School University ofLouisville Louisville, KY William Leigh University ofCentral Florida Orlando, FL . SPRINGER SCIENCE+BUSINESS MEDIA, LLC Library of Congress Cataloging-in-Publication Data Paz, Mario. Structural Dynamics: Theory and Computation I by Mario Paz, William Leigh.-5th ed. p.cm. Includes bibliographical references and index. Additional material to this book can be downloaded from http://extras.springer.com ISBN 978-1-4613-5098-9 ISBN 978-1-4615-0481-8 (eBook) DOI 10.1007/978-1-4615-0481-8 I. Structural dynamics. I. Title. Copyright© 2004 by Springer Science+Business Media New York Originally published by Kluwer Academic Publishers in 2004 Softcover reprint of the bardeover 5th edition 2004 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, mechanical, photo­ copying, recording, or otherwise, without the prior written permission of the publisher, Springer Science+Business Media, LLC. Pennission for books published in Europe: [email protected] Pennissions for books published in the United States of America: [email protected] Printedon acid-free paper. I tun/ ~ heloYed/~ anti,-~ heloYedw ~ J'he., SO"if' of SO"ft' CONTENTS PREFACE TO THE FIFTH EDITION xvii PREFACE TO THE FIRST EDITION xxi PART I STRUCTURES MODELED AS A SINGLE-DEGREE-OF-FREEDOM SYSTEM 1 1 UNDAMPED SINGLE-DEGREE-OF-FREEDOM SYSTEM 3
    [Show full text]
  • An Interdisciplinary Vibrations/Structural Dynamics Course for Civil and Mechanical Students with Integrated Hands on Laboratory
    2006-984: AN INTERDISCIPLINARY VIBRATIONS/STRUCTURAL DYNAMICS COURSE FOR CIVIL AND MECHANICAL STUDENTS WITH INTEGRATED HANDS-ON LABORATORY EXERCISES Richard Helgeson, University of Tennessee-Martin Richard Helgeson is an Associate Professor and Chair of the Engineering Department at the University of Tennessee at Martin. Dr. Helgeson received B.S. degrees in both electrical and civil engineering, an M.S. in electral engineering, and a Ph.D. in structural engineering from the University of Buffalo. He actively involves his undergraduate students in mutli-disciplinary earthquake structural control research projects. He is very interested in engineering educational pedagogy, and has taught a wide range of engineering courses. Page 11.202.1 Page © American Society for Engineering Education, 2006 An Interdisciplinary Vibrations/Structural Dynamics Course for Civil and Mechanical Students with Integrated Hands-on Laboratory Exercises Abstract The University of Tennessee at Martin offers a multi-disciplinary general engineering program with concentrations in civil, electrical, industrial, and mechanical engineering. In this paper the author discusses the development of an engineering course that is taken by both civil and mechanical engineering students. The course has been developed over a number of years, and during that time an integrated laboratory experience has been developed to support the unique interests of both groups of students. The course is required for all mechanical engineering students, while the civil engineering students may take the course as an upper division elective. To insure the success of the course, the author has structured the course to attract both groups of students. This paper discusses the course content and laboratory structure.
    [Show full text]
  • STRUCTURAL DYNAMICS and EARTHQUAKE ENGINEERING UNIT – I THEORY of VIBRATION Two Marks Questions and Answers 1
    V.S.B ENGINEERING COLLEGE, KARUR DEPARTMENT OF CIVIL ENGINEERING CE6701 – STRUCTURAL DYNAMICS AND EARTHQUAKE ENGINEERING UNIT – I THEORY OF VIBRATION Two Marks Questions and Answers 1. What is mean by Frequency? Frequency is number of times the motion repeated in the same sense or alternatively. It is the number of cycles made in one second (cps). It is also expressed as Hertz (Hz) named after the inventor of the term. The circular frequency ω in units of sec-1 is given by 2π f. 2. What is the formula for free vibration response? The vibration which persists in a structure after the force causing the motion has been removed. The corresponding equation under free vibration is mx + kx = 0 3. What are the effects of vibration? i. Effect on Human Sensitivity. ii. Effect on Structural Damage 4. Define damping. Damping is the resistance to the motion of a vibrating body. Damping is a measure of energy dissipation in a vibrating system. The dissipating mechanism may be of the frictional form or viscous form. Unit of damping is N/m/s. 5. What do you mean by Dynamic Response? The Dynamic may be defined simply as time varying. Dynamic load is therefore any load which varies in its magnitude, direction or both, with time. The structural response (i.e., resulting displacements and stresses) to a dynamic load is also time varying or dynamic in nature. Hence it is called dynamic response. 6. What is mean by free vibration? The vibration which persists in a structure after the force causing the motion has been removed is known free vibration.
    [Show full text]
  • Introduction to Structural Dynamics and Aeroelasticity: Second Edition Dewey H
    Cambridge University Press 978-0-521-19590-4 - Introduction to Structural Dynamics and Aeroelasticity: Second Edition Dewey H. Hodges and G. Alvin Pierce Frontmatter More information INTRODUCTION TO STRUCTURAL DYNAMICS AND AEROELASTICITY, SECOND EDITION This text provides an introduction to structural dynamics and aeroelasticity, with an em- phasis on conventional aircraft. The primary areas considered are structural dynamics, static aeroelasticity, and dynamic aeroelasticity. The structural dynamics material em- phasizes vibration, the modal representation, and dynamic response. Aeroelastic phe- nomena discussed include divergence, aileron reversal, airload redistribution, unsteady aerodynamics, flutter, and elastic tailoring. More than one hundred illustrations and ta- bles help clarify the text, and more than fifty problems enhance student learning. This text meets the need for an up-to-date treatment of structural dynamics and aeroelasticity for advanced undergraduate or beginning graduate aerospace engineering students. Praise from the First Edition “Wonderfully written and full of vital information by two unequalled experts on the subject, this text meets the need for an up-to-date treatment of structural dynamics and aeroelasticity for advanced undergraduate or beginning graduate aerospace engineering students.” – Current Engineering Practice “Hodges and Pierce have written this significant publication to fill an important gap in aeronautical engineering education. Highly recommended.” – Choice “...awelcomeadditiontothetextbooks available to those with interest in aeroelas- ticity....Asatextbook, it serves as an excellent resource for advanced undergraduate and entry-level graduate courses in aeroelasticity. ...Furthermore,practicingengineers interested in a background in aeroelasticity will find the text to be a friendly primer.” – AIAA Bulletin Dewey H. Hodges is a Professor in the School of Aerospace Engineering at the Georgia Institute of Technology.
    [Show full text]
  • Nodycon 2019 Program
    FIRST INTERNATIONAL NONLINEAR DYNAMICS CONFERENCE NODYCON 2019 PROGRAM Edited by The NODYCON 2019 Program Committee Department of Structural and Geotechnical Engineering Sapienza University of Rome First International Nonlinear Dynamics Conference Program, Rome, Italy, February 17-20, 2019 INSTITUTIONAL SPONSORS SPONSORS INFORMATION FOR CONFERENCE PARTICIPANTS PRESENTATION GUIDELINES Authors who present their work at technical sessions are expected to use the Conference laptops for their presentation. Each session room will be equipped with a projector with VGA or HDMI cables and a wireless presenter with laser pointer. Authors will be invited to upload their presentations through the dedicated web portal at www.nodycon2019.org. Prior to the session begins, authors are expected to check that their presentation is properly projected. Contributed presentations are 13- minute presentations plus 2 minutes for Q&A (15 mins). Please make sure that all presentations do not exceed these time limits. Plenary talks are 40-minute presentations plus 5 minutes for Q&A (45 mins). POSTER GUIDELINES For the Poster session, standard A0 posters in a free template are expected to be on display on the day of the Poster session. The presenting author is supposed to be available during the Poster session for Q&A. NODYCON 2019 APP An APP developed for iOS/Android ready for free download through Apple/Google stores will display the stream of conference news, the conference program with real-time updates, a tool to customize your conference agenda, maps for the conference rooms, likes on the talks/sessions, and the participants list. A few sample screenshots are shown below. 1 ALI H.
    [Show full text]
  • Aeroelasticity and Structural Dynamics
    Aeroelasticity and Structural Dynamics Aeroelasticity and Structural Dynamics he fourteenth issue of AerospaceLab Journal is dedicated to aeroelasticity and T structural dynamics. Aeroelasticity can be briefly defined as the study of the low frequency dynamic behavior of a structure (aircraft, turbomachine, helicopter rotor, etc.) in an aerodynamic flow. It focuses on the interactions between, on the one hand, the static or vibrational deformations of the structure and, on the Cédric LIAUZUN other hand, the modifications or fluctuations of the aerodynamic flow field. (ONERA) Senior Scientist Aeroelastic phenomena have a strong influence on stability and therefore on the integrity of aeronautical structures, as well as on their performance and durability. In the current context, in which a reduction of the footprint of aeronautics on the environment is sought, in particular by reducing the mass and fuel consumption of aircraft, aeroelasticity problems must be taken into account as early as possible in the design of such structures, whether they are conventional or innovative concepts. It is therefore necessary to develop increasingly efficient and accurate numerical and experimental methods and tools, allowing additional complex physical phenomena to be taken into account. On the other hand, the development of larger and lighter aeronautical structures entails the need to determine the dynamic characteristics of such Nicolas PIET-LAHANIER highly flexible structures, taking into account their possibly non-linear behavior (large (ONERA) displacements, for example), and optimizing them by, for example, taking advantage Senior Scientist of the particular properties of new materials (in particular, composite materials). DOI: 10.12762/2018.AL14-00 This issue of AerospaceLab Journal presents the current situation regarding numerical calculation and simulation methods specific to aeroelasticity and structural dynamics for several applications: fan damping computation and flutter prediction, static and dynamic aeroelasticity of aircraft and gust response.
    [Show full text]
  • Research and Applications in Aeroelasticity and Structural Dynamics at the NASA Langley Research Center
    https://ntrs.nasa.gov/search.jsp?R=19970021267 2020-06-16T02:28:46+00:00Z View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by NASA Technical Reports Server NASA Technical Memorandum 112852 Research and Applications in Aeroelasticity and Structural Dynamics at the NASA Langley Research Center Irving Abel Langley Research Center, Hampton, Virginia May 1997 National Aeronautics and Space Administration Langley Research Center Hampton, Virginia 23681-0001 RESEARCH AND APPLICATIONS IN AEROELASTICITY AND STRUCTURAL DYNAMICS AT THE NASA LANGLEY RESEARCH CENTER Irving Abel Structures Division NASA Langley Research Center MS 121 Hampton, Virginia 23681 USA e-mail address: [email protected] ABSTRACT The Structures Division supports the development of more efficient structures for airplanes, An overview of recently completed programs in helicopters, spacecraft, and space transportation aeroelasticity and structural dynamics research at vehicles. Research is conducted to integrate the NASA Langley Research Center is presented. advanced structural concepts with active-control Methods used to perform flutter clearance studies concepts and smart materials to enhance structural in the wind-tunnel on a high performance fighter performance. Research in aeroelasticity ranges are discussed. Recent advances in the use of from flutter clearance studies of new vehicles smart structures and controls to solve aeroelastic using aeroelastic models tested in the wind tunnel, problems, including flutter and gust response are to the development of new concepts to control presented. An aeroelastic models program aeroelastic response, and to the acquisition of designed to support an advanced high speed civil unsteady pressures on wind-tunnel models for transport is described.
    [Show full text]
  • ASEN 5111 Aeroelasticity
    ASEN 5111: Introduction to Aeroelasticity F. Demet Ulker Spring- 2020 E-mail: [email protected] Web: Office Hours: T/TH 5:30pm-6:30pm Class Hours: T/TH 4:00pm-5:15pm Course Description This course provides an introductory level knowledge in theoretical and experimental founda- tions of aeroelasticity. A short review on the 2D aerodynamics and discrete and continuous system vibration analysis methods will be followed by static and dynamic aeroelastic phenom- ena. Along with the classical flutter analysis, several other critical flutter conditions such as Body Freedom Flutter will be discussed in the class. Analytical and numerical based approximate so- lution techniques will be introduced. ASWING will be used for coupled flight dynamics and aeroelastic analysis and experimental simulations. Homeworks are designed to complement the subjects covered in the class, hence different aeroelastic phenomena including fixed wing and rotary wing aeroelastic systems, and control couplings will be analyzed. Prerequisite Requires corequisite courses of APPM 2360, ASEN 2001. • Sufficient familiarity with vibrations: response of multimass and continuous systems, free vibration modes, normal coordinates, and variational principles in dynamics. Desirable: MATH 2400, ASEN 3112, ASEN 4123. • Sufficient familiarity with low-speed aerodynamics and flight dynamics of aerospace vehi- cles. Desirable: ASEN 3111, ASEN 3128. • Sufficient familiarity with stability analysis. Desirable: ASEN 5012. • Prior programming skills in MATLAB. 1 ASEN 5111 Reference Materials [1] J. Wright and J. Cooper, Introduction to Aircraft Aeroelasticity and Loads, 2nd ed., ser. aerospace series. Wiley, 2015. [2] R. L. Bisplinghoff and H. Ashley, Principles of Aeroelasticity. Dover, 1962. [3] D. Hodges and G. Pierce, Introduction to Structural Dynamics and Aeroelasticity, ser.
    [Show full text]
  • Using Shaking Table to Study Different Methods of Reduceing Effects of Buildings Pounding During Earthquake
    13th World Conference on Earthquake Engineering Vancouver, B.C., Canada August 1-6, 2004 Paper No. 698 USING SHAKING TABLE TO STUDY DIFFERENT METHODS OF REDUCEING EFFECTS OF BUILDINGS POUNDING DURING EARTHQUAKE Arash REZAVANI1 and A.S. MOGHADAM2 SUMMARY Pounding of adjacent buildings has been one of major reasons of damages of building in earthquakes. Therefore there is a need to investigate this phenomenon, both experimentally and analytically. This paper begins with a general study on the effect of pounding. Then two series of shaking table experiments on small scale moment resisting frames subjected to harmonic excitation and seismic loading are described. For new buildings, there are provisions in the seismic design building codes regarding the distance between adjacent buildings to accommodate the potential of pounding. However, for existing building the solution is not as easy. Therefore, final part of the paper explains a series of experiments regarding some measures to reduce the damaging effects of pounding. The measures include increasing distance of the buildings, application of impact absorbing material, and connecting the two building together. The results of experiments indicate the effectiveness, also problems associated with each method. INTRODUCTION The 1985 Mexico City earthquake caused much attention to the damaging effects of pounding between adjacent buildings. Of course the effects of pounding as a cause of damage have been reported in numerous other earthquakes [1,2,3]. However, the wide spread damages resulted from pounding in the 1985 Mexico City earthquake illustrate it as a major mode of failure for building [2]. 40% of the buildings are reported to have pounding problem and 15% of the total collapses were related to pounding [1,2,4].
    [Show full text]