Forum: Reliability & Maintainability Questions and Answers

Topic: Reliability & Maintainability Questions and Answers

Topic Posted by: Reliability & Maintainability Forum ( )
Organization: System Reliability Center
Date Posted: Mon Aug 31 12:47:36 US/Eastern 1998

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Posted by: C K ( )
Organization:DSO National Laboratories
Date posted: Wed Sep 8 22:57:05 US/Eastern 2004
Subject: ESS vs EWT
Recently, I came across some statements in MIL-STD-810F, Method 514.5 (pg 514.5-1, para 1.2e and Annex B, para 2.1.8) on ESS. In para 1.2e, it was written that "Where units do not necessarily receive the same exposures, such as multiple passes throuth ESS, apply the maximum allowable exposures to the units used for environmental test as pre-conditioning for the environment tests." In Annex B, para 2.1.8, it says EWT can be used to substitute ESS when the material is to be subjected to worthiness test and then used in the field. My questions are: 1) Can EWT really be used to substitute ESS for the scenerio mentioned in Annex B? 2) What if my unit is only subject to 1 grms vibration (human transportation) in field, is EWT of 1 grms, 10mins/axis for 3 axes sufficient to replace ESS? 3) If I conduct ESS on the said unit using 6 grms, 10 mins/axis (critical axis only), will it kill the unit? Kindly advise. Thanks.


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