Modal Test and Model Correlation of NASA Plum Brook Station Mechanical Vibration Facility Head Expander
Explore the source record for details and available documents.
Emma L Pierson↗
SEARCH · Search NASA
Results for “test correlation”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Test-Analysis Modal Correlation of Rocket Engine Structures in Liquid Hydrogen -Phase II
Explore the source record for details and available documents.
Andy Brown↗
Correlations of Different Surface Tests: Tire Behavior Math Model for the High Speed Civil Transport (HSCT) and Michelin Tire Properties Tests for Boeing 777
In the surfaces correlation study, several different volumetric and drainage measurement techniques for classifying surface texture were evaluated as part of a major study to develop and improve methods for predicting tire friction performance on all types of pavement. The objective of the evaluation was to seek relationships between the different techniques, and to relate those results to surface frictional characteristics. We needed to know how each of the tests could be related to each other. Another of my assigned projects was to make a tire behavior math model for the High Speed Civil Transport (HSCT) using the same methods used for the space shuttle a few years ago. A provided third order equation with two variables was used. This model will also be used for studies with the Boeing 777. Only a few changes will be necessary to adapt it for this other aircraft, which is the newest offered by Boeing. In my final project I was involved with testing the tires for this new aircraft using the Aircraft Landing Dynamics Facility (ALDF) test carriage within the carriage house at LaRC. A 50 inch diameter radial tire manufactured by Michelin Aircraft Tire Corporation had to be tested to double overload of 114,000 pounds. The rated load of each tire is 57,000 pounds, but Boeing required tests assuming failure of a companion tire that could have cost Michelin approximately $12 million to build a facility to provide the required test capability. Here at LaRC, only minimum modifications to the facility were required to perform this specific test.
Roman, Ivan↗
Loads Correlation of a Full-Scale Proprotor on the Tiltrotor Test Rig
In 2018, a full-scale isolated proprotor test was conducted in the USAF National Full-Scale Aerodynamics Complex (NFAC) at NASA Ames. The test article was the 3-bladed Bell 699 research rotor derived from the AW609 rotor. For this test, the NASA Tiltrotor Test Rig (TTR) and rotor were installed in the 40- by 80-foot test section. Correlations between the 2018 test data and predictions from the comprehensive analysis CAMRAD II for blade and yoke (flexbeam) loads and rotor torque are presented. The full range of conversion to helicopter modes is covered: conversion 30-, 45-, and 60-deg TTR yaw, and helicopter 75- and 90-deg TTR yaw. The flap moment correlation is reasonable to good; the pitch link load and torsion moment are uniformly underpredicted. The measured 2P lag moment and 2P torque are not captured by the analysis. The inability to predict the 2P component is currently attributed to the analytical assumption of a perfect gimbal, whereas the actual test gimbal may be operating imperfectly and thus introducing the 2P harmonic. A new analytical model that accounts for non-ideal gimbal operation is needed.
Kottapalli, Sesi↗
Correlation of low speed wind tunnel and flight test data for V/STOL aircraft
The availability of wind tunnel test data for correlation purposes of the same V/STOL aircraft tested in flight is very limited. This is due in a large part to size limitations of wind tunnels and the number of wind tunnels available for testing of full-scale aircraft. Wind tunnel tests are described for two research aircraft - the XV-5B fan-in-wing aircraft and the YOV-10 RCF (rotating cylinder flap) aircraft - in the NASA Ames 40- by 80-foot wind tunnel. The tests were conducted specifically to provide for correlation between wind tunnel and in-flight aerodynamics and noise test data. Correlation between aerodynamic and noise data are presented and testing techniques that are related to the accuracy of the data, or that might affect the correlations, are discussed. The correlation of noise measurements made with a J-85 engine mounted on a F-106 aircraft during low altitude flyovers with the same J-85 engine mounted on a model and tested in the Ames 40- by 80-foot wind tunnel are also reported.
Cook, W. L.↗
Tests of blending and correlation of distillate fuel properties
The development of a fuel test matrix, results from tests of several blends of distillate aircraft fuels, and the use of correlations in formulation determination during a NASA-sponsored program to identify new aircraft fuels are described. The program was initiated in order to characterize fuel blends which are appropriate for different types of combustors in use and under development. The fuels were required to feature a specified range of properties. Attention is given to fuel volatility, hydrogen content, aromatic content, freezing point, kinematic viscosity, and naphthalene content. Paraffinic and naphtenic base stocks were employed, using alkyl benzene, naphthene benzenes, and naphthalenes to adjust the blend properties. Categories for the test fuels comprised source-controlled and composition controlled fuels. Test results and compositions of various fuels are provided.
Erwin, J.↗
Application of High Speed Digital Image Correlation in Rocket Engine Hot Fire Testing
Hot fire testing of rocket engine components and rocket engine systems is a critical aspect of the development process to understand performance, reliability and system interactions. Ground testing provides the opportunity for highly instrumented development testing to validate analytical model predictions and determine necessary design changes and process improvements. To properly obtain discrete measurements for model validation, instrumentation must survive in the highly dynamic and extreme temperature application of hot fire testing. Digital Image Correlation has been investigated and being evaluated as a technique to augment traditional instrumentation during component and engine testing providing further data for additional performance improvements and cost savings. The feasibility of digital image correlation techniques were demonstrated in subscale and full scale hotfire testing. This incorporated a pair of high speed cameras to measure three-dimensional, real-time displacements and strains installed and operated under the extreme environments present on the test stand. The development process, setup and calibrations, data collection, hotfire test data collection and post-test analysis and results are presented in this paper.
Gradl, Paul R.↗
Psyche Magnetometer Engineering Model Test and Thermal Model Correlation to Validate Operational Thermal Requirement
Psyche Fluxgate Magnetometer candidate fabricated by UCLA has a critical temperature gradient requirement inside the magnetometer sensor head. Since the temperature gradient requirement is a driving factor for the magnetometer operation and science data collection at 16 Psyche, it is critical to validate and verify this requirement via modeling and test. In this work, a thermal vacuum test was completed for Psyche flight-like magnetometer engineering model. Flight-like environments were simulated for a hot operational case (after launch), a cold survival case (cruise), and two cold operational cases to characterize thermal performance of the instrument. An additional, non-flight, steady-state test case was completed to better correlate the magnetometer thermal model. During the test, sensitive Cernox temperature sensors with accuracy of ±0.1°C were used to precisely characterize the temperature gradient and correlate the model to the best accuracy. Collected test data indicated power consumption of 28% lower than predicted. The temperature gradient measured met the expected value and the requirement. Test data indicated the magnetometer also met the AFTs in relevant hot and cold environments. Test Results were used to correlate the thermal model. The correlated thermal model will be integrated to the spacecraft thermal model to predict magnetometer thermal performance while collecting science data in Psyche orbits.
Caron, Ryan↗
Evaluation of bead-stiffened metal panels
Potential weight efficiency for bead-stiffened panels has been demonstrated through fabrication and testing. Theoretically optimum design concepts were identified, and small specimens were tested under combined compression, shear, and bending to determine local buckling failure loads and to verify theory. Large optimized panels were then designed and tested under combined loads. Correlation of test data for large circular tubular panels with theory was conservative and consistent, and indicated reliable and acceptable design theory. Tests of fluted tubular panels indicated general instability failures at loads far below the design values due to nonlinear distortions. Further study of the fluted tubular configuration will be required if its potential weight efficiency is to be attained.
Shideler, J. L.↗
Structural analysis of cylindrical thrust chambers, volume 2
Analytical results are presented which predict cumulative plastic deformation characteristic of damage observed in coolant channel walls of regeneratively cooled rocket thrust chambers. The damage consists of bulging and plastic flow which leads to thinout and rupture of the channel wall under the combined effects of high pressures, high temperatures and temperature gradients experienced during cyclic firings of actual test chambers. Analytical predictions correlate with test results.
Armstrong, W. H.↗
The NASA/industry Design Analysis Methods for Vibrations (DAMVIBS) program: McDonnell-Douglas Helicopter Company achievements
This paper presents a summary of some of the work performed by McDonnell Douglas Helicopter Company under NASA Langley-sponsored rotorcraft structural dynamics program known as DAMVIBS (Design Analysis Methods for VIBrationS). A set of guidelines which is applicable to dynamic modeling, analysis, testing, and correlation of both helicopter airframes and a large variety of structural finite element models is presented. Utilization of these guidelines and the key features of their applications to vibration modeling of helicopter airframes are discussed. Correlation studies with the test data, together with the development and applications of a set of efficient finite element model checkout procedures, are demonstrated on a large helicopter airframe finite element model. Finally, the lessons learned and the benefits resulting from this program are summarized.
Toossi, Mostafa↗
Comparison of Hard Surface and Soft Soil Impact Performance of a Crashworthy Composite Fuselage Concept
A comparison of the soft soil and hard surface impact performance of a crashworthy composite fuselage concept has been performed. Specifically, comparisons of the peak acceleration values, pulse duration, and onset rate at specific locations on the fuselage were evaluated. In a prior research program, the composite fuselage section was impacted at 25 feet per second onto concrete at the Impact Dynamics Research Facility (IDRF) at NASA Langley Research Center. A soft soil test was conducted at the same impact velocity as a part of the NRTC/RITA Crashworthy and Energy Absorbing Structures project. In addition to comparisons of soft soil and hard surface test results, an MSC. Dytran dynamic finite element model was developed to evaluate the test analysis correlation. In addition, modeling parameters and techniques affecting test analysis correlation are discussed. Once correlated, the analytical methodology will be used in follow-on work to evaluate the specific energy absorption of various subfloor concepts for improved crash protection during hard surface and soft soil impacts.
Sareen, Ashish K.↗
Vertical Drop Testing and Analysis of the WASP Helicopter Skid Gear
Human occupant modeling and injury risk assessment have been identified as areas of research for improved prediction of rotorcraft crashworthiness within the NASA Aeronautics Program's Subsonic Rotary Wing Project. As part of this effort, an experimental program was conducted to assess the impact performance of a skid gear for use on the WASP kit-built helicopter, which is marketed by HeloWerks, Inc. of Hampton, Virginia. Test data from a drop test at an impact velocity of 8.4 feet-per-second were used to assess a finite element model of the skid gear test article. This assessment included human occupant analytic models developed for execution in LS-DYNA. The test article consisted of an aluminum skid gear mounted beneath a steel plate. A seating platform was attached to the upper surface of the steel plate, and two 95th percentile Hybrid III male Aerospace Anthropomorphic Test Devices (ATDs) were seated on the platform and secured using a four-point restraint system. The goal of the test-analysis correlation is to further the understanding of LS-DYNA ATD occupant models and responses in the vertical (or spinal) direction. By correlating human occupant experimental test data for a purely vertical impact with the LS-DYNA occupant responses, improved confidence in the use of these tools and better understanding of the limitations of the automotive-based occupant models for aerospace application can begin to be developed.
Fuchs, Yvonne T.↗
Vertical Drop Testing and Analysis of the WASP Helicopter Skid Gear
Human occupant modeling and injury risk assessment have been identified as areas of research for improved prediction of rotorcraft crashworthiness within the NASA Aeronautics Program s Subsonic Rotary Wing Project. As part of this effort, an experimental program was conducted to assess the impact performance of a skid gear for use on the WASP kit-built helicopter, which is marketed by HeloWerks, Inc. of Hampton, Virginia. Test data from a drop test at an impact velocity of 8.4 feet-per-second were used to assess a finite element model of the skid gear test article. This assessment included human occupant analytic models developed for execution in LS-DYNA. The test article consisted of an aluminum skid gear mounted beneath a steel plate. A seating platform was attached to the upper surface of the steel plate, and two 95th percentile Hybrid III male Aerospace Anthropomorphic Test Devices (ATDs) were seated on the platform and secured using a four-point restraint system. The goal of the test-analysis correlation is to further the understanding of LS-DYNA ATD occupant models and responses in the vertical (or spinal) direction. By correlating human occupant experimental test data for a purely vertical impact with the LS-DYNA occupant responses, improved confidence in the use of these tools and better understanding of the limitations of the automotive-based occupant models for aerospace application can begin to be developed.
Fuchs, Yvonne T.↗
Stability Analysis of Intertank Formed Skin/Stringer Compression Panel with Simulated Damage
The External Tank (ET) is a component of the Space Shuttle launch vehicle that contains fuel and oxidizer. During launch, the ET supplies the space shuttle main engines with liquid hydrogen and liquid oxygen. In addition to supplying fuel and oxidizer, it is the backbone structural component of the Space Shuttle. It is comprised of a liquid hydrogen (LH2) tank and a liquid oxygen (LOX) tank, which are separated by an Intertank. The Intertank is a stringer-stiffened cylindrical structure with hat-section stringers that are roll formed from aluminum-lithium alloy Al-2090. Cracks in the Intertank stringers of the STS-133 ET were noticed after a November 5, 2010 launch attempt. The cracks were approximately nine inches long and occurred on the forward end of the Intertank (near the LOX tank), along the fastener line, and were believed to have occurred while loading the ET with the cryogenic propellants. These cracks generated questions about the structural integrity of the Intertank. In order to determine the structural capability of the Intertank with varying degrees of damage, a finite element model (FEM) simulating a 1995 compression panel test was analyzed and correlated to test data. Varying degrees of damage were simulated in the FEM, and non-linear stability analyses were performed. The high degree of similarity between the compression panel and the Intertank provided confidence that the ET Intertank would have similar capabilities.
Harper, David W.↗
Sasquatch Footprint Tool
The Crew Exploration Vehicle Parachute Assembly System (CPAS) is the parachute system for NASA s Orion spacecraft. The test program consists of numerous drop tests, wherein a test article rigged with parachutes is extracted or released from an aircraft. During such tests, range safety is paramount, as is the recoverability of the parachutes and test article. It is crucial to establish an aircraft release point that will ensure that the article and all items released from it will land in safe locations. A new footprint predictor tool, called Sasquatch, was created in MATLAB. This tool takes in a simulated trajectory for the test article, information about all released objects, and atmospheric wind data (simulated or actual) to calculate the trajectories of the released objects. Dispersions are applied to the landing locations of those objects, taking into account the variability of winds, aircraft release point, and object descent rate. Sasquatch establishes a payload release point (e.g., where the payload will be extracted from the carrier aircraft) that will ensure that the payload and all objects released from it will land in a specified cleared area. The landing locations (the final points in the trajectories) are plotted on a map of the test range. Sasquatch was originally designed for CPAS drop tests and includes extensive information about both the CPAS hardware and the primary test range used for CPAS testing. However, it can easily be adapted for more complex CPAS drop tests, other NASA projects, and commercial partners. CPAS has developed the Sasquatch footprint tool to ensure range safety during parachute drop tests. Sasquatch is well correlated to test data and continues to ensure the safety of test personnel as well as the safe recovery of all equipment. The tool will continue to be modified based on new test data, improving predictions and providing added capability to meet the requirements of more complex testing.
Bledsoe, Kristin↗
Implementation and Testing of VLBI Software Correlation at the USNO
The Washington Correlator (WACO) at the U.S. Naval Observatory (USNO) is a dedicated VLBI processor based on dedicated hardware of ASIC design. The WACO is currently over 10 years old and is nearing the end of its expected lifetime. Plans for implementation and testing of software correlation at the USNO are currently being considered. The VLBI correlation process is, by its very nature, well suited to a parallelized computing environment. Commercial off-the-shelf computer hardware has advanced in processing power to the point where software correlation is now both economically and technologically feasible. The advantages of software correlation are manifold but include flexibility, scalability, and easy adaptability to changing environments and requirements. We discuss our experience with and plans for use of software correlation at USNO with emphasis on the use of the DiFX software correlator.
Fey, Alan↗