1、Best Practices Entry: Best Practice Info:a71 Committee Approval Date: 2000-03-17a71 Center Point of Contact: GSFCa71 Submitted by: Wil HarkinsSubject: Spacecraft Deployed Appendage Test Guidelines Practice: Perform thorough testing of all flight deployable appendages, including the design, analysis,
2、 fabrication and checkout of the test facility and related hardware; the planning and conducting of the actual tests; the post-test data reduction and analysis; and the re-testing after correction of anomalies.Programs that Certify Usage: N/ACenter to Contact for Information: GSFCImplementation Meth
3、od: This Lesson Learned is based on Reliability Guideline Number GT-TE-2403 from NASA Technical Memorandum 4322A, NASA Reliability Preferred Practices for Design and Test.Benefit:Adherence to this Guideline gives confidence that mechanisms will operate successfully during flight. The design phase an
4、alytical methods and results are verified. Testing determines margins to show by how much the design requirements are exceeded and pinpoints potential problem areas. Experience gained from failures and anomalies during testing help prevent recurrence in future programs.Provided by IHSNot for ResaleN
5、o reproduction or networking permitted without license from IHS-,-,-Implementation Method:In order to realize the benefits of a deployable appendages test program, the following steps should be taken:1. Use the design requirements for the hardware to be tested to generate a list of tests that will v
6、erify that each requirement will be met. This list should include how many times each test must be conducted, and the pass/fail criteria for each test.2. From this list, determine which tests can be combined to save time and costs.3. Select the critical design parameters for which test values and ma
7、rgins are to be measured.4. Decide what facilities and equipment will be needed for the tests. Design, analyze, fabricate, and check out any new items needed.5. Determine what personnel will be required for each test.6. Put together an overall schedule of tests, paying particular attention to the lo
8、gistics of personnel, facilities, and material needed for each test.7. Use the results of the previous steps to write a comprehensive test plan.8. Follow the plan to set up and conduct the tests, then perform data reduction and analysis.9. Write up the results of the tests in one or more test report
9、s.10. Correct deficiencies revealed in testing and re-test to verify the modified configuration.Technical Considerations:To realize all the benefits, the test program should include:1. Thorough testing to qualify the design and correlate the design analysis. Acceptance criteria must be established p
10、rior to the start of testing. 2. Testing at greater extremes (temperatures, vacuum, loads) than expected during flight to determine margins. 3. Testing of flight-like hardware to prove designs. 4. Testing of actual flight hardware to prove workmanship and determine values of specific design paramete
11、rs. 5. Comprehensive part and component testing, to lessen the risk of failure at subsystem and system program phases, when such failures are very costly. Parts and components include: a72 Bearingsa72 Springsa72 Dampersa72 Motors, gear trainsProvided by IHSNot for ResaleNo reproduction or networking
12、 permitted without license from IHS-,-,-a72 Switches, position indicators6. Testing of subsystems (such as drive assemblies, hinge assemblies, gimbals, etc.) should include the following general tests: a72 Mass propertiesa72 Component interfacesa72 System interfacea72 Subsystem performance verificat
13、ion (including margins)a72 Subsystem strength verificationa72 Subsystem life, including lubricant/lubricant systemsa72 Thermal vacuuma72 EMI/EMCa72 Magnetica72 Vibration/acoustics7. Specific subsystem tests should include (where applicable): a72 Restraint/release assembly testsa72 Hinge assembly tes
14、tsa72 Drive assembly tests (solar array-antenna)a72 Gimbal assembly tests8. System tests of complete deployable appendages should include: a72 System tests should match flight configuration as closely as possible.a72 Where practical, full deployment testing in simulated zero-G environment, including
15、 release, deployment, and lock-in.a72 Deployment in thermal-vacuum is preferable, but generally impractical.a72 Vibro/acoustic testing of the system in launch configuration should precede full deployment testing.a72 Parameters to measure (where applicable) should include: a73 Deployment time, releas
16、e to lock-ina73 Motor currenta73 Stiffness stowed and deployeda73 Alignmenta73 Envelope of motion during deploymenta73 Electrical integrity of cables across hinges and gimbalsa73 Release shocka73 Velocity at end of travela73 Torque marginsa73 System life, if applicableProvided by IHSNot for ResaleNo
17、 reproduction or networking permitted without license from IHS-,-,-9. In-depth investigation of all anomalies. 10. Test facilities include: a72 Design and Analysis - deployment testing of large appendages usually requires special, tailor-made facilities to simulate actual flight conditions as closel
18、y as possible, and to perform special engineering tests. Such hardware includes: a73 G-negation devicesa73 Inertial load simulatorsa73 Thermal control devices capable of producing temperature levels and gradientsa73 Fixtures for environmental testsa73 Fixtures for conducting stiffness measurements,
19、modal tests, etc.a72 Facility Design Parameters a73 Simulation of mechanical and electrical launch configuration interfacesa73 Space available for full deploymenta73 Type , number, size, and location of g-negation supportsa73 Weight, size, cost, manufacturability of fixturesa73 Transportability of f
20、ixtures, if requireda72 Analysis Parameters a73 Load carrying capacity of fixturesa73 Effect of fixtures on measured dataa73 Pre-test predictions and establishment of pass/fail criteriaa72 Pre-testa72 Environmental test fixtures must be calibrated and safety tested in actual facility prior to useTec
21、hnical Rationale:Testing of deployable appendages for spacecraft differs somewhat from the testing of other space hardware. It involves special considerations for dealing with large, cumbersome devices that usually require some degree of manual handing after each operation. Since ground testing is d
22、one in a 1-g environment, a complex facility is usually required for simulating the zero-g space condition (g-negation device).This guideline covers the complete test program for spacecraft deployable appendages, including the general tests that also pertain to other space hardware, and the tests sp
23、ecifically pertinent to deployable appendages.References:Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-1. GSFC Engineering Directorate paper, “Spacecraft Deployable Appendages,“ May 1992.2. Reliability Preferred Practice No. PD-EC-1101, Environment
24、al FactorsImpact of Non-Practice: Without a comprehensive test program, the following types of failure would not be caught and corrected prior to flight:a71 No lock-in, or poor lock-ina71 No releasea71 Deployment stops prematurelya71 Electrical cable degradationa71 Incorrect final positioninga71 Dep
25、loyment rate too high, resulting in high impact loads, thus possibly causing failures in other systemsa71 Fluid leak (causes contamination)a71 Improper wiringRelated Practices: N/AAdditional Info: Approval Info: a71 Approval Date: 2000-03-17a71 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-,-,-
