NASA Contractor Report 4500 The Middeck O-Gravity Dynamics Experiment Summary Report Edward F. Crawley, Marthinus C. Van Schoor, and Edward B. Bokhour CONTRACT NAS1-1S690 MARCH 1993 ( SA CR 4500) THE MIDDECK 0- RAV I TY DYNAj IC S EXPE~ IME T N93- 30376 Summ ry R port (MIT) 107 P Unc~as Hl/18 0176815 . . NI\5/\ NASA Contractor Report 4500 The Middeck 0-Gravity Dynamics Experiment Summary Report Edward F. Crawley, Marthinus C. Van Schoor, and Edward B. Bokhour Massachusetts Institute of Technology Cambridge, Massachusetts Prepared for Langley Research Center under Contract NAS1-18690 National Aeronautics and Space Administration Office of Management Scientific and Technical Information Program 1993 Page intentionally left blank Abstract The overall experimental and analytical effort centered around the Middeck 0-gravity Dynamics Experiment is presented in this report. The results of the Structural Test Article (STA) experiments are given first. An analytic and experimental study of the changes in the modal parameters of space structural test articles from one- to zero-gravity is presented. Deployable, erectable, and rotary modules were assembled to form three one- and two-dimensional structures, in which variations in bracing wire and rotary joint preload could be introduced. The structures were modeled as if hanging from a suspension system in one-gravity, and unconstrained, as if free floating in zero-gravity. The analysis is compared with ground experimental measurements, made on a spring/wire suspension system with a nominal plunge frequency of one Hertz, and with measurements made on the Shuttle middeck. The degree of change in linear modal paramenters as well as the change in nonlinear nature of the response is examined. Trends in modal parameters are presented as a function of force amplitude, joint preload, and ambient gravity. Next the results of the Fluid Test Article (FTA) experiments are given. An experimental study of the change in the lateral slosh behavoir of contained fluids betwen earth and space is presented. The experimental apparatus used to determine the slosh characteristics is described and a nonlinear analytical model of a coupled fluid/spacecraft is outlined. The forced response characteristics of silicone oil and distilled water in cylindrical tanks with either a flat or spherical bottom are reported and discussed. A comparison of the measured earth and space results identifies and highlights the effects of gravity on the linear and nonlinear slosh behavior of these fluids. A technical description of the hardware and software systems used in the Middeck 0-gravity Dynamics Experiment (MODE) is presented last. MODE consists of three major elements: the Experiment Support Module, a dynamics test bed providing computer experiment control, analog signal conditioning, power conditioning, an operator interface consisting of a keypad and display, experiment electrical and thermal control, and archival data storage; the Fluid Test Article assembly, used to investigate the dynamics of fluid-structure iii interaction in zero-gravity; and the Structural Test Article for investigating the open-loop dynamics of structures in zero-gravity. iv Acknowledgments This work was supported by the NASA Instep Flight Experiments Program, and the NASA Langley Research Center Reference No. NAS1-18690, with Dr. Sherwin Beck as monitor. The ground and analytical studies were supported in part by the NASA Headquarters Grant No. ASGW-1335 to the MIT Space Engineering Research Center, with Dr. Robert Hayduk as technical monitor, and by NASA Headquarters Grant No. NAGW-2014 with Mr. Samuel Venneri as technical monitor. The McDonnell Douglas Space Systems Company was intrumental in the supply of the structural test article, and the funding at McDonnell Douglas Space Systems Company of the experiments performed there. The authors also acknowledge the contribution to the report writing and editing by Mark S. Barlow, Brett P. Masters of MIT, Andrew S. Bicos of McDonnell Douglas Space Systems Company, and R. Grimes, M. Hachkowski, C. Krebs, and J. Zapetis of Payload Systems, Inc. V Contents 1 Introduction ........................................................................................ 1 2 Structural Test Article Results ......................................................... 3 2.1 Introduction ...................................................................................................... 3 2.2 Hardware and Test Procedure ...................................................................... 5 2.2.1 Configurations 5 2.2.2 Modules 6 2.2.3 Sensors and Actuator 8 2.2.4 Test Procedures and Data Reduction 9 2.3 Modeling ......................................................................................................... 11 2.3.1 Evaluation and Models 11 2.3.2 Development Models 11 2.3.3 1-g Models 12 2.4 Test Results ..................................................................................................... 13 2.4.1 Test Matrix Selection 13 2.4.2 Ground Test Results 14 2.4.3 Orbital Test Results 16 2.4.4 Comparison of Finite Element and Experimental Results 21 2.5 Conclusions .................................................................................................... 23 Figures 26 Tables 34 2.6 References for Chapter 2 .............................................................................. 38 3 Fluid Test Article Results ................................................................ 39 3.1 Introduction ................................................................................................... 39 3.2 Hardware and Test Procedure .................................................................... 40 3.2.1 Hardware Description 40 3.2.2 Fluids and Tank Geometries 44 3.2.3 Test Procedures and Data Reduction 46 3.3 Modeling ........................................................................................................ 47 3.3.1 Nonlinear Fluid Phenomena 47 3.3.2 Nonlinear Fluid/Spacecraft Model 50 vii 3.3.3 Linearized Models 53 3.4 Test Results .................................................................................................... 54 3.4.1 Test Matrix Selection 54 3.4.2 Ground Test Results 56 3.4.3 Orbital Test Results 60 3.4.4 Comparison of Ground and Orbital Results 62 3.5 Conclusions .................................................................................................... 63 Figures 65 3.6 References for Chapter 3 ............................................................................... 75 4 Flight Systems and Mission Activities ......................................... 77 4.1 Introduction ..................................................................................................... 77 4.2 Flight Systems ................................................................................................ 78 4.2.1 Development 78 4.2.2 Functional Elements 80 4.2.3 Fluid Test Assembly 82 4.2.4 Structural Test Article 84 4.2.5 Experiment Support Module 85 4.2.6 Certification 93 4.3 MiSsion Activities .......................................................................................... 93 4.3.1 Fluid Dynamics Testing 93 4.3.2 Structural Dynamics Testing 96 4.4 Summary ......................................................................................................... 99 viii Chapter 1: Introduction In 1986 the Massachusetts Institute of Technology proposed to NASA the Middeck 0-gravity Dynamics Experiment (MODE), a cost effective experiment for the investigation of fluid-spacecraft interaction and structural dynamics in zero-gravity. The objective of MODE was to gather data on the dynamic interaction between fluid volumes stored in tanks and spacecraft dynamics, and on the dynamics of multi-element statically indeterminate space structures. The data derived were to be correlated with zero-gravity simulations in order to validate analytical models, which could then be applied to a broader class of problems. MODE was funded by the NASA OAST In-Step program in 1988. The MIT Space Engineering Research Center was the prime contractor with cooperation from McDonnell Douglas Space Systems Company, who supplied the structural test articles. All other support hardware was manufactured by Payload Systems Inc. The NASA Langley Research Center was the technical and programmatic monitor of the program. The experiment was flown, and on orbit data were taken during the STS-48 mission in September of 1991. Mission specialists Mark Brown and James Buchli were assigned to the MODE team. With the assistance of Brown, Buchli performed the majority of the test protocols. From the day after launch, until July 1992, the approximately three billion measurements taken during the MODE flight and ground test program were reduced and examined. This report constitutes the summary data report on this experiment. This report is divided into three subsequent chapters: one describing the research program which centers around the the Structural Test Article (STA), the next describing the investigation focused on the Fluid Test Article (FTA), and the final chapter describing the hardware and flight operations. Chapter 2 is a summary of the analytic and experimental investigation of the changes from one- to zero-gravity in the modal parameters of the structural test article. Both on earth and on orbit, a set of deployable,, erectable, and rotary modules were assembled to form three one- and two-dimensional configurations of the STA. In order to control the degree of nonlinearity, variations in bracing wire and rotary joint preload were introduced. As a complement to the experimental program, the structures were modeled by linear finite element methods. The resulting analysis is compared with ground experimental measurements, and with measurements made on the Shuttle middeck. The degreeof changein linear modal parameters aswell asthe changein nonlinear natureof the STAresponseis reported. The experimental and analytical investigation of the influence of gravity on the lateral slosh behavior of contained fluids is presented in Chapter 3. The experimental apparatus usedto determine the sloshcharacteristics,the FFA and associatedequipment, is described. A nonlinear analytical model of acoupled fluid/spacecraft systemis then outlined. The forced responsecharacteristics of silicone oil and distilled water in cylindrical tanks with flat or spherical bottoms are reported and discussed. A comparison of the measured earth and on orbit results identifies and highlights the effectsofgravity on the linear andnonlinear sloshbehavior ofthesefluids. Chapter 4 describes in more detail the hardware built for the MODE experiment, aswell astheon orbit operations. The principal hardware elements were the Structural Test Article, the Fluid Test Article, and the Experimental Support Module, or ESM. The ESM contained, in the spaceof one middeck locker, all of the functionality of a small dynamics laboratory. Operated by the crew over the courseof three dayson orbit, the ESMcontrolled the experiment, andrecorded the datafor subsequentanalysis. ! 2