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At least 19 records

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NASA NTRS1989

Creating a VAPEPS database: A VAPEPS tutorial

A procedural method is outlined for creating a Vibroacoustic Payload Environment Prediction System (VAPEPS) Database. The method of presentation employs flowcharts of sequential VAPEPS Commands used to create a VAPEPS Database. The commands are accompanied by explanatory text to the right of the command in order to minimize the need for repetitive reference to the VAPEPS user's manual. The method is demonstrated by examples of varying complexity. It is assumed that the reader has acquired a basic knowledge of the VAPEPS software program.

Graves, George↗

NASA NTRS1991

Vibroacoustic Payload Environment Prediction System (VAPEPS): VAPEPS management center remote access guide

A Vibroacoustic Payload Environment Prediction System (VAPEPS) Management Center was established at the JPL. The center utilizes the VAPEPS software package to manage a data base of Space Shuttle and expendable launch vehicle payload flight and ground test data. Remote terminal access over telephone lines to the computer system, where the program resides, was established to provide the payload community a convenient means of querying the global VAPEPS data base. This guide describes the functions of the VAPEPS Management Center and contains instructions for utilizing the resources of the center.

Fernandez, J. P.↗

NASA NTRS1989

A modified VAPEPS method for predicting vibroacoustic response of unreinforced mass loaded honeycomb panels

VAPEPS (VibroAcoustic Payload Environment Prediction System) is a computer program used to predict the vibroacoustic response of a structure. An alternate VAPEPS modeling technique, the Modified NASA Lewis Method, is an improvement for modeling unreinforced mass loaded honeycomb panels. The Modified NASA Lewis Method prediction is compared to the standard ASMS VAPEPS prediction, and the acoustic test data for three spacecraft panels. An analytical method of computing variance is presented and used to compute 95 percent confidence levels. These levels are compared to the standard VAPEPS confidence levels and to the envelope of the test data. As a result of using the new methodology suggested in the paper, both the mean prediction and the 95 percent confidence level prediction agree well with the test data in both spectral shape and magnitude. Therefore, the Modified NASA Lewis Method prediction methodology may be used to define more realistic random vibration test levels.

Mcnelis, Mark E.↗

NASA NTRS1989

A modified VAPEPS method for predicting vibroacoustic response of unreinforced mass loaded honeycomb panels

VAPEPS (vibroAcoustic Payload Environment Prediction System) is a computer program used to predict the vibroacoustic response of a structure. An alternate VAPEPS modeling technique, the Modified NASA Lewis Method, is an improvement for modeling unreinforced mass loaded honeycomb panels. The Modified NASA Lewis Method prediction is compared to the standard ASMS VAPEPS prediction, and the acoustic test data for three spacecraft panels. An analytical method of computing variance is presented and used to compute 95 percent confidence levels. These levels are compared to the standard VAPEPS confidence levels and to the envelope of the test data. As a result of using the new methodology suggested in the paper, both the mean prediction and the 95 percent confidence level prediction agree well with the test data in both spectral shape and magnitude. Therefore, the Modified NASA Lewis Method prediction methodology may be used to define more realistic random vibration test levels.

Mcnelis, Mark E.↗

NASA NTRS1986

Vibroacoustic payload environment prediction system (VAPEPS): Data base management center remote access guide

A Vibroacoustic Data Base Management Center has been established at the Jet Propulsion Laboratory (JPL). The center utilizes the Vibroacoustic Payload Environment Prediction System (VAPEPS) software package to manage a data base of shuttle and expendable launch vehicle flight and ground test data. Remote terminal access over telephone lines to a dedicated VAPEPS computer system has been established to provide the payload community a convenient means of querying the global VAPEPS data base. This guide describes the functions of the JPL Data Base Management Center and contains instructions for utilizing the resources of the center.

Thomas, V. C.↗

NASA NTRS1994

VAPEPS Management Center

A VibroAcoustic Payload Environment Prediction System (VAPEPS) Management Center is established and being maintained at JPL. VAPEPS is a computer program that utilizes statistical energy analysis (SEA) theory and SEA extrapolation methods to predict the vibroacoustic environments of complex systems. The program is commonly utilized to establish random vibration and acoustic test requirements for aerospace components exposed to launch environments. It can also be used in the payload or launch vehicle design process for control or mitigation of the launch or on-orbit vibration and acoustic environments, as well as to calculate acoustically induced stresses in structures such as solar panels and reflectors.

VAPEPS↗

NASA NTRS1992

Predicting microgravity levels for space station using VAPEPS

The topics are presented in viewgraph form and include: a vibroacoustic payload environment prediction system (VAPEPS); objectives of the JPL space station analysis effort; statistical energy analysis (SEA); VAPEPS Space Station Freedom (SSF) model description; noise control treatments; and SSF microgravity preliminary analysis results.

Badilla, G.↗

NASA NTRS1988

VAPEPS user's reference manual, version 5.0

This is the reference manual for the VibroAcoustic Payload Environment Prediction System (VAPEPS). The system consists of a computer program and a vibroacoustic database. The purpose of the system is to collect measurements of vibroacoustic data taken from flight events and ground tests, and to retrieve this data and provide a means of using the data to predict future payload environments. This manual describes the operating language of the program. Topics covered include database commands, Statistical Energy Analysis (SEA) prediction commands, stress prediction command, and general computational commands.

Park, D. M.↗

NASA NTRS1991

Using VAPEPS for noise control on Space Station Freedom

Noise environmental control is an important design consideration for Space Station Freedom (SSF), both for crew safety and productivity. Acoustic noise requirements are established to eliminate fatigue and potential hearing loss by crew members from long-term exposure and to facilitate speech communication. VAPEPS (VibroAcoustic Payload Environment Prediction System) is currently being applied to SSF for prediction of the on-orbit noise and vibration environments induced in the 50 to 10,000 Hz frequency range. Various sources such as fans, pumps, centrifuges, exercise equipment, and other mechanical devices are used in the analysis. The predictions will be used in design tradeoff studies and to provide confidence that requirements will be met. Preliminary predictions show that the required levels will be exceeded unless substantial noise control measures are incorporated in the SSF design. Predicted levels for an SSF design without acoustic control treatments exceed requirements by 25 dB in some one-third octave frequency bands.

Badilla, Gloria↗

NASA NTRS1992

An assessment of the microgravity and acoustic environments in Space Station Freedom using VAPEPS

The Vibroacoustic Payload Environment Prediction System (VAPEPS) was used to predict the stationary on-orbit environments in one of the Space Station Freedom modules. The model of the module included the outer structure, equipment and payload racks, avionics, and cabin air and duct systems. Acoustic and vibratory outputs of various source classes were derived and input to the model. Initial results of analyses, performed in one-third octave frequency bands from 10 to 10,000 Hz, show that both the microgravity and acoustic environments will be exceeded in some one-third octave bands with the current SSF design. Further analyses indicate that interior acoustic level requirements will be exceeded even if the microgravity requirements are met.

Bergen, Thomas F.↗

NASA NTRS1994

VAPEPS Management Center

VAPEPS is a computer program that utilizes statistical energy analysis (SEA) theory and SEA extrapolation methods to predict the vibroacoustic environments in complex systems.

vibroacoustic↗

NASA NTRS1987

A Vibroacoustic Database Management Center for Shuttle and expendable launch vehicle payloads

A Vibroacoustic Database Management Center has recently been established at the Jet Propulsion Laboratory (JPL). The center uses the Vibroacoustic Payload Environment Prediction System (VAPEPS) computer program to maintain a database of flight and ground-test data and structural parameters for both Shuttle and expendable launch-vehicle payloads. Given the launch-vehicle environment, the VAPEPS prediction software, which employs Statistical Energy Analysis (SEA) methods, can be used with or without the database to establish the vibroacoustic environment for new payload components. This paper summarizes the VAPEPS program and describes the functions of the Database Management Center at JPL.

Thomas, Valerie C.↗

NASA NTRS1982

Development of a vibroacoustic data base management and prediction system for payloads

A data base management and prediction system called vibroacoustic payload environment prediction system (VAPEPS) was developed to serve as a repository for shuttle or extendable booster payload component flight and ground test data. This system is to be made available to the aerospace community for multiple uses including that of establishing the vibroacoustic environment for new payload components. The VAPEPS data includes that spectral information normally processed from vibration and acoustic measurements (e.g., power spectra, sound pressure level spectra, etc.). Results of development to provide this capability by NASA Goddard Space Flight Center and Lockheed Missiles and Space Company are described.

On, F. J.↗

NASA NTRS1985

Vibroacoustic study of the NASA Goddard Space Flight Center OSS-1 payload

A comparative evaluation of shuttle liftoff and ground test random response data obtained from the Office of Space Science-1 (OSS-1) pallet payload flown in the cargo bay of STS-3 is presented. The study was initiated to evaluate the possibility that the payload flight vibration response can exceed that occurred during ground test when the ground test acoustic excitation is normalized to the flight acoustic environment. In addition, the analytically derived response from the Vibroacoustic Payload Environment Prediction System (VAPEPS) is compared with OSS-1 ground test results.

Lee, Y. A.↗

NASA NTRS1989

Noise environment reduction foam spheres in space

The advent of lightweight fairings for new spacecraft and the increased thrust of new launch vehicles have intensified the need for better techniques for predicting and for reducing the low frequency noise environment of spacecraft at liftoff. This paper presents a VAPEPS (VibroAcoustic Payload Environment Prediction System) parametrical analysis of the noise reduction of spacecraft fairings and explores a novel technique for increasing the low frequency noise reduction of lightweight fairing by approximately 10 dB.

Scharton, Terry↗

NASA NTRS1990

Prediction of interior noise due to random acoustic or turbulent boundary layer excitation using statistical energy analysis

The feasibility of predicting interior noise due to random acoustic or turbulent boundary layer excitation was investigated in experiments in which a statistical energy analysis model (VAPEPS) was used to analyze measurements of the acceleration response and sound transmission of flat aluminum, lucite, and graphite/epoxy plates exposed to random acoustic or turbulent boundary layer excitation. The noise reduction of the plate, when backed by a shallow cavity and excited by a turbulent boundary layer, was predicted using a simplified theory based on the assumption of adiabatic compression of the fluid in the cavity. The predicted plate acceleration response was used as input in the noise reduction prediction. Reasonable agreement was found between the predictions and the measured noise reduction in the frequency range 315-1000 Hz.

Grosveld, Ferdinand W.↗

NASA NTRS1992

Acoustic fill factors for a 120 inch diameter fairing

Data from the acoustic test of a 120-inch diameter payload fairing were collected and an analysis of acoustic fill factors were performed. Correction factors for obtaining a weighted spatial average of the interior sound pressure level (SPL) were derived based on this database and a normalized 200-inch diameter fairing database. The weighted fill factors were determined and compared with statistical energy analysis (VAPEPS code) derived fill factors. The comparison is found to be reasonable.

Lee, Y. Albert↗

NASA NTRS2000

Vibroacoustic Response of Solar Panels: Case Study

Large surface area, lightweight structures, such as solar panels, are easily excited by sound and often experience high acceleration responses during acoustic tests.

SEA vibroacoustics VAPEPS case study D-11341↗