欢迎来到麦多课文档分享! | 帮助中心 海量文档,免费浏览,给你所需,享你所想!
麦多课文档分享
全部分类
  • 标准规范>
  • 教学课件>
  • 考试资料>
  • 办公文档>
  • 学术论文>
  • 行业资料>
  • 易语言源码>
  • ImageVerifierCode 换一换
    首页 麦多课文档分享 > 资源分类 > PDF文档下载
    分享到微信 分享到微博 分享到QQ空间

    REG NASA-LLIS-0779-2000 Lessons Learned - Environmental Test Sequencing.pdf

    • 资源ID:1018425       资源大小:15.36KB        全文页数:3页
    • 资源格式: PDF        下载积分:10000积分
    快捷下载 游客一键下载
    账号登录下载
    微信登录下载
    二维码
    微信扫一扫登录
    下载资源需要10000积分(如需开发票,请勿充值!)
    邮箱/手机:
    温馨提示:
    如需开发票,请勿充值!快捷下载时,用户名和密码都是您填写的邮箱或者手机号,方便查询和重复下载(系统自动生成)。
    如需开发票,请勿充值!如填写123,账号就是123,密码也是123。
    支付方式: 支付宝扫码支付    微信扫码支付   
    验证码:   换一换

    加入VIP,交流精品资源
     
    账号:
    密码:
    验证码:   换一换
      忘记密码?
        
    友情提示
    2、PDF文件下载后,可能会被浏览器默认打开,此种情况可以点击浏览器菜单,保存网页到桌面,就可以正常下载了。
    3、本站不支持迅雷下载,请使用电脑自带的IE浏览器,或者360浏览器、谷歌浏览器下载即可。
    4、本站资源下载后的文档和图纸-无水印,预览文档经过压缩,下载后原文更清晰。
    5、试题试卷类文档,如果标题没有明确说明有答案则都视为没有答案,请知晓。

    REG NASA-LLIS-0779-2000 Lessons Learned - Environmental Test Sequencing.pdf

    1、Best Practices Entry: Best Practice Info:a71 Committee Approval Date: 2000-04-13a71 Center Point of Contact: JPLa71 Submitted by: Wil HarkinsSubject: Environmental Test Sequencing Practice: Perform dynamic tests prior to performing thermal-vacuum tests on flight hardware.Abstract: Preferred Practice

    2、 for Design & Test. If the thermal-vacuum tests do not follow the dynamics tests, more intermittent or incipient discontinuity type failures may go undetected. If the defects are not detected during assembly level tests and are subsequently detected during the system level tests, redesign or rework

    3、at this late stage of the process could cause delays, increase costs, or make it necessary to accept additional risk that might have been avoided. If the defects are not detected at the system level, the defects may then cause hardware anomalies during the mission, and in the extreme could cause a m

    4、ission failure. Perform dynamic tests prior to performing thermal-vacuum tests on flight hardware.Programs that Certify Usage: This practice has been used on Mariner Series, Voyager, Viking, GalileoCenter to Contact for Information: JPLImplementation Method: This Lesson Learned is based on Reliabili

    5、ty Practice number PT-TE-1412 from NASA Technical Memorandum 4322A, NASA Reliability Preferred Practices for Design and Test.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Benefit:Experience has shown that until the thermal-vacuum tests are performe

    6、d, many failures induced during dynamics tests are not detected because of the short duration of the dynamics tests. In addition, the thermal-vacuum test on flight hardware at both the assembly level and the system level provides a good screen for intermittent as well as incipient hardware failures.

    7、Implementation Method:Perform flight hardware testing in the following sequence:1. Sinusoidal or transient vibration, random vibration, pyroshock, and acoustics, as required. The order among these dynamics tests may be interchanged.2. Thermal-vacuum testing.To assure that this sequence is followed,

    8、specify in the test specifications or test plans, as appropriate, that all dynamic tests will be performed prior to thermal-vacuum tests on both the assembly and system levels.During the normal flight sequence, the launch environment is followed by vacuum and potential temperature extremes. In this

    9、flight sequence, the flight hardware is therefore exposed to acoustics and vibration followed by vacuum and temperature variations. Consequently, by performing dynamics tests prior to thermal-vacuum tests, the actual flight sequence is simulated. Also, if the flight sequence produces synergistic eff

    10、ects, the synergism will be simulated.In addition, preserving the sequence of the service environments in the environmental test program is a widely accepted practice. As a result, the effect of reversing the test sequence on spacecraft failure rates has not been quantified. However, evidence exists

    11、 that many acoustic induced failures have not been detected until the spacecraft is exposed to the thermal-vacuum environment. These failures may not be detected during acoustics tests because of the short one-minute duration or a non-operating power condition. Typically, the identified failures tha

    12、t could be related to or caused by the dynamic acoustic environment were bad solder joints, intermittents, bad bearings, broken wires, poor welds, leaks, foreign materials, etc.An example of a failure that might be induced by dynamic tests but not revealed until thermal vacuum would be a broken wire

    13、 or solder joint. This defect might be induced by acoustics but not be detected during the acoustic test due to the short duration or to an unpowered or unmonitored state of the affected equipment. During post-acoustic functional testing, the wire or solder joint broken ends may be making adequate c

    14、ontact to show electrical continuity. In the subsequent thermal-vacuum test, the thermal distortions could cause loss of contact, allowing the failure to be detected. Reversing the test sequence could result in the defect not being induced until after thermal vacuum test and not detected until expos

    15、ure to the flight thermal environment.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Even if all defects precipitated by the dynamics tests are revealed during the test, or during post-test functional testing, performing the dynamic tests first will

    16、 still have the advantage of increasing the probability that defects will be detected earlier, when they will have less impact on the system test program cost and schedule.Impact of Non-Practice: If the thermal-vacuum tests do not follow the dynamics tests, more intermittent or incipient discontinui

    17、ty type failures may go undetected. If the defects are not detected during assembly level tests and are subsequently detected during the system level tests, redesign or rework at this late stage of the process could cause delays, increase costs, or make it necessary to accept additional risk that mi

    18、ght have been avoided. If the defects are not detected at the system level, the defects may then cause hardware anomalies during the mission, and in the extreme could cause a mission failure.Related Practices: N/AAdditional Info: Approval Info: a71 Approval Date: 2000-04-13a71 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-,-,-


    注意事项

    本文(REG NASA-LLIS-0779-2000 Lessons Learned - Environmental Test Sequencing.pdf)为本站会员(jobexamine331)主动上传,麦多课文档分享仅提供信息存储空间,仅对用户上传内容的表现方式做保护处理,对上载内容本身不做任何修改或编辑。 若此文所含内容侵犯了您的版权或隐私,请立即通知麦多课文档分享(点击联系客服),我们立即给予删除!




    关于我们 - 网站声明 - 网站地图 - 资源地图 - 友情链接 - 网站客服 - 联系我们

    copyright@ 2008-2019 麦多课文库(www.mydoc123.com)网站版权所有
    备案/许可证编号:苏ICP备17064731号-1 

    收起
    展开