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All sourcesNASA NTRSDOE OSTI
NASA NTRS2004

NASA Handbook for Spacecraft Structural Dynamics Testing

Recent advances in the area of structural dynamics and vibrations, in both methodology and capability, have the potential to make spacecraft system testing more effective from technical, cost, schedule, and hardware safety points of view. However, application of these advanced test methods varies widely among the NASA Centers and their contractors. Identification and refinement of the best of these test methodologies and implementation approaches has been an objective of efforts by the Jet Propulsion Laboratory on behalf of the NASA Office of the Chief Engineer. But to develop the most appropriate overall test program for a flight project from the selection of advanced methodologies, as well as conventional test methods, spacecraft project managers and their technical staffs will need overall guidance and technical rationale. Thus, the Chief Engineer's Office has recently tasked JPL to prepare a NASA Handbook for Spacecraft Structural Dynamics Testing. An outline of the proposed handbook, with a synopsis of each section, has been developed and is presented herein. Comments on the proposed handbook is solicited from the spacecraft structural dynamics testing community.

vibrations↗
NASA NTRS2010

Advanced Stirling Convertor Dynamic Test Approach and Results

The U.S. Department of Energy (DOE), Lockheed Martin Corporation (LM), and NASA Glenn Research Center (GRC) have been developing the Advanced Stirling Radioisotope Generator (ASRG) for use as a power system for space science missions. As part of the extended operation testing of this power system, the Advanced Stirling Convertors (ASC) at NASA GRC undergo a vibration test sequence intended to simulate the vibration history that an ASC would experience when used in an ASRG for a space mission. This sequence includes testing at workmanship and flight acceptance levels interspersed with periods of extended operation to simulate prefueling and post fueling. The final step in the test sequence utilizes additional testing at flight acceptance levels to simulate launch. To better replicate the acceleration profile seen by an ASC incorporated into an ASRG, the input spectra used in testing the convertors was modified based on dynamic testing of the ASRG Engineering Unit (ASRG EU) at LM. This paper outlines the overall test approach, summarizes the test results from the ASRG EU, describes the incorporation of those results into the test approach, and presents the results of applying the test approach to the ASC-1 #3 and #4 convertors. The test results include data from several accelerometers mounted on the convertors as well as the piston position and output power variables.

Meer, David W.↗
NASA NTRS2009

Advanced Stirling Convertor Dynamic Test Approach and Results

The U.S. Department of Energy (DOE), Lockheed Martin (LM), and NASA Glenn Research Center (GRC) have been developing the Advanced Stirling Radioisotope Generator (ASRG) for use as a power system for space science missions. As part of the extended operation testing of this power system, the Advanced Stirling Converters (ASC) at NASA John H. Glenn Research Center undergo a vibration test sequence intended to simulate the vibration history of an ASC used in an ASRG for a space mission. This sequence includes testing at Workmanship and Flight Acceptance levels interspersed with periods of extended operation to simulate pre and post fueling. The final step in the test sequence utilizes additional testing at Flight Acceptance levels to simulate launch. To better replicate the acceleration profile seen by an ASC incorporated into an ASRG, the input spectra used in testing the convertors was modified based on dynamic testing of the ASRG Engineering Unit ( ASRG-EU) at Lockheed Martin. This paper presents the vibration test plan for current and future ASC units, including the modified input spectra, and the results of recent tests using these spectra. The test results include data from several accelerometers mounted on the convertors as well as the piston position and output power variables.

Meer, David W.↗
NASA NTRS1978

Development of structural dynamic test environments for subsystems and components

Structural dynamic environmental test levels were developed for the thematic mapper instrument, components of the Tandberg-Hanssen instrument, and components of the International Ultraviolet Explorer spacecraft using NASTRAN structural models and test data. Both static and dynamic NASTRAN analyses were used. The model size required could be as small as 300 degrees of freedom for the static analysis and as large as 4000 degrees of freedom or more for the high frequency dynamic analysis. An important step in the development of the levels is model verification by test. The launch environments that generally dictate many important features of the design of an instrument or component are steady state acceleration, sinusoidal vibration, and random vibration.

Coladonato, R. J.↗
NASA NTRS2000

A Historical Perspective on Dynamics Testing at the Langley Research Center

The experience and advancement of Structural dynamics testing for space system applications at the Langley Research Center of the National Aeronautics and Space Administration (NASA) over the past four decades is reviewed. This experience began in the 1960's with the development of a technology base using a variety of physical models to explore dynamic phenomena and to develop reliable analytical modeling capability for space systems. It continued through the 1970's and 80's with the development of rapid, computer-aided test techniques, the testing of low-natural frequency, gravity-sensitive systems, the testing of integrated structures with active flexible motion control, and orbital flight measurements, It extended into the 1990's where advanced computerized system identification methods were developed for estimating the dynamic states of complex, lightweight, flexible aerospace systems, The scope of discussion in this paper includes ground and flight tests and summarizes lessons learned in both successes and failures.

Horta, Lucas G.↗
NASA NTRS1972

Derivation of mass and stiffness matrices from dynamic test data.

A technique is described by which orthonormal modal vectors, computed from dynamic test response data, are used to derive mass, stiffness, and damping matrices for a discrete model of the distributed elastic system. Matrices thus computed from subsystems tests may be readily incorporated into larger system models. The method has been applied to a test of the Saturn V S-II stage LOX tank-engine support system. The dynamic responses of the discrete model are shown to correlate well with test data throughout the frequency range tested.

Thoren, A. R.↗
NASA NTRS2005

NASA Handbook for Spacecraft Structural Dynamics Testing

Recent advances in the area of structural dynamics and vibrations, in both methodology and capability, have the potential to make spacecraft system testing more effective from technical, cost, schedule, and hardware safety points of view. However, application of these advanced test methods varies widely among the NASA Centers and their contractors. Identification and refinement of the best of these test methodologies and implementation approaches has been an objective of efforts by the Jet Propulsion Laboratory on behalf of the NASA Office of the Chief Engineer. But to develop the most appropriate overall test program for a flight project from the selection of advanced methodologies, as well as conventional test methods, spacecraft project managers and their technical staffs will need overall guidance and technical rationale. Thus, the Chief Engineer's Office has recently tasked JPL to prepare a NASA Handbook for Spacecraft Structural Dynamics Testing. An outline of the proposed handbook, with a synopsis of each section, has been developed and is presented herein. Comments on the proposed handbook are solicited from the spacecraft structural dynamics testing community.

Kern, Dennis L.↗
NASA NTRS2016

Reconstructed Parachute System Performance During the Second LDSD Supersonic Flight Dynamics Test

NASA’s Low-Density Supersonic Decelerators project (LDSD) has developed and tested four new aerodynamic decelerator technologies for future Mars missions: two attached toroidal inflatable decelerators, a ballute, and a large supersonic parachute. On June 8, 2015, the project conducted a high-altitude, supersonic flight test of a 30.5-meter supersonic Ringsail (SSRS) canopy at the US Navy’s Pacific Missile Range Facility (PMRF) on Kauai, HI. This test, the second in a series of Supersonic Flight Dynamics Tests (SFDT-2), allowed the LDSD project to test the deployment and performance of its parachute decelerator system in the wake of a representative test vehicle (a 4.7-meter aeroshell and 6-meter toroidal inflatable aerodynamic decelerator) at conditions relevant to Mars entry for the second time. The parachute decelerator system consisted of the SSRS main parachute and a 4.4-meter ballute (called the parachute deployment device, or PDD) for its extraction. The ballute was mortar-deployed at a Mach number of 2.78 and a dynamic pressure of 493 Pa, and inflated with the aid of a water-methanol based gas generator. After flying in the wake of the test vehicle for ten seconds, the PDD was released and allowed to extract the main parachute pack. The SSRS reached line-stretch at a Mach number of 2.37 and dynamic pressure of 602 Pa. Following full inflation, the propagation of a tear in the canopy led to the failure of the parachute skirt band and to the subsequent failure of the vent band. The test vehicle was instrumented with load sensors, inertial sensors, and high-speed and high resolution cameras that provided data on the performance of the PDD and SSRS through deployment, inflation, and flight. This paper describes the resulting reconstructed behavior of the PDD and SSRS during deployment and inflation, their aerodynamic performance on SFDT-2, the failure of the SSRS shortly after full inflation, and the LDSD project’s investigation into its underlying causes.

O'Farrell, Clara↗
NASA NTRS1980

Design of a dynamic test platform for autonomous robot vision systems

The concept and design of a dynamic test platform for development and evluation of a robot vision system is discussed. The platform is to serve as a diagnostic and developmental tool for future work with the RPI Mars Rover's multi laser/multi detector vision system. The platform allows testing of the vision system while its attitude is varied, statically or periodically. The vision system is mounted on the test platform. It can then be subjected to a wide variety of simulated can thus be examined in a controlled, quantitative fashion. Defining and modeling Rover motions and designing the platform to emulate these motions are also discussed. Individual aspects of the design process are treated separately, as structural, driving linkages, and motors and transmissions.

Rich, G. C.↗
NASA NTRS1991

Contact dynamics testing of automated three point docking mechanism

TRW has conducted an extensive Contact Dynamics Test Program (CDTP) of the Three Point Docking Mechanism (TPDM). The CDTP tested the ability of the TPDM latches to capture and automatically dock to target spacecraft. The target selected was the Hubble Space Telescope (HST). Mock ups of the TPDM with its three latches and the docking interface of the HST were constructed at the Marshall Space Flight Center (MSFC) in Huntsville, Alabama for use in the tests. The tests were performed at the Flat Floor and Six Degree of Freedom (6-DOF) facilities at MSFC.

Spitzer, Christopher J.↗
NASA NTRS1964

Dynamic Tests of V/STOL Transport Models

This paper presents a summary of results obtained in dynamic tests of free-flight models of various configurations suitable for V/STOL transport aircraft at the NASA Langley Research Center. The configurations covered will be the tilt-wing propeller-driven type as represented by the XC-142A tri-service transport, the fan-in-wing type as represented by the XV-5A research airplane, and the jet-lift type as represented by the Dornier 00-31 transport. The test techniques themselves are not described in this paper since they have been described in detail previously in references 1 and 2.

Dynamic stability↗
NASA NTRS2016

Post-Flight Assessment of Low Density Supersonic Decelerator Flight Dynamics Test 2 Simulation

NASA's Low Density Supersonic Decelerator (LDSD) project conducted its second Supersonic Flight Dynamics Test (SFDT-2) on June 8, 2015. The Program to Optimize Simulated Trajectories II (POST2) was one of the flight dynamics tools used to simulate and predict the flight performance and was a major tool used in the post-flight assessment of the flight trajectory. This paper compares the simulation predictions with the reconstructed trajectory. Additionally, off-nominal conditions seen during flight are modeled in the simulation to reconcile the predictions with flight data. These analyses are beneficial to characterize the results of the flight test and to improve the simulation and targeting of the subsequent LDSD flights.

Dutta, Soumyo↗
NASA NTRS1988

Design, fabrication, and dynamic testing of a V-groove radiator mechanical development unit

This paper describes the design, fabrication, and dynamic testing of a V-groove radiator development unit. The intended goal was to survive the dynamic environment of the Mars Observer mission. The development unit was designed to achieve a temperature of 80 K with a heat load of about 80 milliwatts. An analysis was performed to predict the thermal performance of the development unit. The radiator with a mass mockup of a Gamma Ray Spectrometer detector, the most massive of the candidate Mars Observer instrument detectors (1.7 Kg), passed vibration and acoustic testing to the Mars Observer requirements in effect at that time.

Petrick, S. Walter↗
NASA NTRS2008

Low-Speed Flight Dynamic Tests and Analysis of the Orion Crew Module Drogue Parachute System

A test of a dynamically scaled model of the NASA Orion Crew Module (CM) with drogue parachutes was conducted in the NASA-Langley 20-Foot Vertical Spin Tunnel. The primary test objective was to assess the ability of the Orion Crew Module drogue parachute system to adequately stabilize the CM and reduce angular rates at low subsonic Mach numbers. Two attachment locations were tested: the current design nominal and an alternate. Experimental results indicated that the alternate attachment location showed a somewhat greater tendency to attenuate initial roll rate and reduce roll rate oscillations than the nominal location. Comparison of the experimental data to a Program To Optimize Simulated Trajectories (POST II) simulation of the experiment yielded results for the nominal attachment point that indicate differences between the low-speed pitch and yaw damping derivatives in the aerodynamic database and the physical model. Comparisons for the alternate attachment location indicate that riser twist plays a significant role in determining roll rate attenuation characteristics. Reevaluating the impact of the alternate attachment points using a simulation modified to account for these results showed significantly reduced roll rate attenuation tendencies when compared to the original simulation. Based on this modified simulation the alternate attachment point does not appear to offer a significant increase in allowable roll rate over the nominal configuration.

Hahne, David E.↗
NASA NTRS2016

Construction of Supersonic Flight Dynamics Test (SFDT-2) Vehicle Monte Carlo Splashdown Footprints for Use in Range Safety and Recovery Planning

Overview of Low Density Supersonic Decelerator (LDSD) SFDT-2 ( Supersonic Flight Dynamics Test-2) flight profile; Description of Monte Carlo flight dynamics simulations performed; Modeling and uncertainties; Results with statistical prediction of test vehicle splashdown location; Use of Monte Carlo results for range safety and recovery planning.

Strauss, Bill↗
NASA NTRS1974

Estimation of structural parameters from dynamic test data

Parameters for a lumped linear model approximating a distributed elastic structure are determined from dynamic test data comprised of several mode shapes and frequencies. Measurement errors, nonlinear response, and nonmeasurable quantities such as mode slope components are accommodated. Some mass and stiffness parameters may be known accurately, whereas the remainder are to be estimated. The method entails minimizing a quadratic function of the difference between corresponding modes and frequencies of the theoretical model and the test specimen. This technique was applied to some actual vibration test data, and the special techniques that are required to overcome convergence problems are described.

Hall, B. M.↗