REG NASA-LLIS-0784--2000 Lessons Learned Powered-On Vibration.pdf

1、Best Practices Entry: Best Practice Info:a71 Committee Approval Date: 2000-04-14a71 Center Point of Contact: JPLa71 Submitted by: Wilson HarkinsSubject: Powered-On Vibration Practice: Supply power to electronic assemblies during vibration, acoustics, and pyroshock and monitor the electrical function

2、s continuously while the excitation is applied.Abstract: Preferred Practice for Design & Test. A failure to conduct powered-on vibration test may increase the risk of flight equipment containing flaws or intermittencies, such as electrical arcing, open circuits, and relay chatter, that may cause mis

3、sion compromises or hardware failures. Supply power to electronic assemblies during vibration, acoustics, and pyroshock, and monitor the electrical functions continuously while the excitation is applied.Programs that Certify Usage: This practice has been used on the Mariner series, Viking, Voyager,

4、Magellan and Galileo programs.Center to Contact for Information: JPLImplementation Method: This Lesson Learned is based on Reliability Practice number PT-TE-1405, from NASA Technical Memorandum 4322A, Reliability Preferred Practices for Design and Test.Aids in the detection of intermittent or incipi

5、ent failures in electronic circuitry not otherwise found. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-This reliability practice benefits even those electronics not powered during launch.Apply service power to electronics assemblies. Monitor as ma

6、ny circuits as possible for intermittent behavior or change in voltage/current level. Record for later analysis the most critical electrical functions. Employ instrumentation such as a storage logic analyzer to monitor relay contacts, especially during pyroshock testing.The NASA and industry practic

7、e of powering electronic assemblies during dynamics testing has proven to be effective in uncovering otherwise undetected “soft“ failures. Studies by the Institute of Environmental Sciences, the U.S. military, Tustin Technological Institute, Hobbes Engineering, and others have all arrived at the sam

8、e general conclusion: power-on vibration is a valuable tool for exposing latent defects in electronic hardware with the eventual resultant improvement in product quality.Intermittencies in electronic circuitry can often be detected during vibration but may not be observed under ambient functional te

9、sting. These intermittencies may not reappear until after launch, where they sometimes degenerate into hard failures.Examples of these intermittencies include:a71 Component shorts due to internal conductive particles,a71 Loose or contaminated connectors,a71 Fractured component-to-board solder joints

10、,a71 Electrical arcing,a71 Data number changes in digital equipment, anda71 Relay transfer or chatter.Powering of electronic equipment during vibration allows for detection of failures or intermittent conditions when they occur. This can be extremely useful in diagnosing the problem and formulating

11、corrective action. In vibration, it is advantageous to know in what environment, level, axis, and time the anomaly occurred. Also, this procedure allows a test to be discontinued at the time the anomaly occurs to avoid the potential for further damage.Impact of Non-Practice: A failure to conduct pow

12、ered-on vibration test may increase the risk of flight equipment containing flaws or intermittencies, such as electrical arcing, open circuits, and relay chatter, that may cause mission compromises or hardware failures.Related Practices: N/AProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Additional Info: Approval Info: a71 Approval Date: 2000-04-14a71 Approval Name: Eric Raynora71 Approval Organization: QSa71 Approval Phone Number: 202-358-4738Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-