technical Rteport

1 -, lJAD. technical Rteport * .. - United States Army Belvoir Research, Development & Engineering Center Fort Belvoir, Virginia 22060-5606. Report'2477. Environmental Stress", Screening (ES Gud Authored By: William , Project tj Report Date: January 1989. Distribution unlimited; approved for public release.'al fELECTE. ~ ,~"APR 07198. 89 4 n P/. Destroy this report when it is no longer needed. Do not return it to the originator. The citation in this report of trade names of commercially available products does not constitute official endorsement or approval of the use of such products.)

2 UNCLASSIFIED. SECURITY CLASSIFICATION OF THIS PAGE D x o 6. REPORT DOCUMENTATION PAGE Form Approved OMB No. 0704-0188. la. REPORT SECURITY CLASSIFICATION lb. RESTRICTIVE MARKINGS. Unclassified None 2a. SECURITY CLASSIFICATION AUTHORITY 3. DISTRIBUTION/AVAILABILITY OF REPORT. Distribution unlimited; approved for public release. 2b. DECLASSIFICATION/DOWNGRADING SCHEDULE. 4. PERFORMING ORGANIZATION REPORT NUMBER(S) 5. MONITORING ORGANIZATION REPORT NUMBER(S). 2477. 6a. NAME OF PERFORMING ORGANIZATION 6b. OFFICE SYMBOL 7a. NAME OF MONITORING ORGANIZATION.

3 Bcivoir RD&E Center (Iapplicable). Product Assurance Division STRBE-TQE. 6c. ADDRESS (City, State, and ZIP Code) 7b. ADDRESS (City, State, and ZIP Code). Fort Belvoir, VA 22060-5606. Ba. NAME OF FUNDING/SPONSORING 8b. OFFICE SYMBOL 9. PROCUREMENT INSTRUMENT IDENTIFICATION NUMBER. ORGANIZATION applicable). (If 8c. ADDRESS (City, State, and ZIP Code) 10. SOURCE OF FUNDING NUMBERS. PROGRAM PROJECT TASK IWORK UNIT. ELEMENT NO. NO. NO. ACCESSION NO. 11. TITLE (Include Security Classification). Environmental Stress Screening (ESS) Guide (U).

4 12. PERSONAL AUTHOR(S). William H. Homer, Project Manager, and Evaluation Research Corporation, McLean, VA. 13a. TYPE OF REPORT 13b. TIME COVERED 14. DATE OF REPORT (Year,Month, Day) 15. PAGE COUNT. Final IFROM TO January 1989[ 117. 16. SUPPLEMENTARY NOTATION. 17, eOSATI ES 1 .'UBJECT TERMS (Continue on reverse if necessary and identify by block number). FIELD GROUP SUB-GROUP -Therma]cycling. $:' ". ' .'. Random vibration. ("" - ) -i'. 19, ABSTRCT (Continue on reverse if necessary and identify by block number).._-This guide provides a step-by-step approach to the planning, implementing, and monitoring of an Environmental Stress Screening (ESS).

5 Plfrogram for Army Materiel Commao.(AMCylIroop Support Command (TROSCOM) hardware contracts and repair activities. This guide'10- not replace logical thinking on the part of the user, but ,4P~presenrthe various elements of an ESS Program and advise the user in their selection and use. 4_7--I- 20. DISTRIBUTION/AVAILABILITY OF ABSTRACT 21. ABSTRACT SECURITY CLASSIFICATION. [-IUNCLASSIFIEDIUNLIMITED ]SAME AS REPORT,- DTIC USERS Unclassified 22a. NAME OF RESPONSIBLE INDIVIDUAL 22b. TELEPHONE (Include Area Code) 22c. Office Symbol William H.)

6 Homer 703-664-5771 STRBE-TQE. DD Form 1473, JUN 86 Previous editions are obsolete. SECURITY CLASSIFICATION OF THIS PAGE. i UNCLASSIFIED. PREFACE. PURPOSE. This guide provides a step-by-step approach to the planning, implementing, and monitoring of an Environmental Stress Screening (ESS) Program for Army Materiel Command (AMC) Troop Support Command (TROSCOM) hardware contracts and repair activities. This guide will not replace logical thinking on the part of the user, but will present the various elements of an ESS. Program and advise the user in their selecton and use.

7 AUDIENCE. This guide is intended for use by product assurance engineers, project engineers, project managers, item managers, and administrative personnel who are responsible for planning, implementing, or monitoring an ESS Program. WHAT IS ESS? In any manufacturing or assembly process involving people and machinery, a small percentage of defects usually occurs. There are many techniques used by industry to reduce the number of defects remaining in hardware when it leaves the factory. These techniques include process control, training, inspection, and testing.

8 A number of these defects will escape detection in the factory in spite of these standard defect prevention techniques. These undetected defects will be manifest as early life failures during the hardware's field use. These early life, or infant, failures will reduce field reliability, even though the number of undetected defects is small. For this reason, it is important to detect and eliminate as many defects as possible before the hardware leaves the factory. " The increasing complexity of mechanical equipment and miniaturization of electronic equipment has made traditional methods of defect detection less efficient.

9 One of the most effective techniques used to identify and eliminate these defects is ivironmental stress screening (ESSI. ESS is the process of applying environmental stresses, in conjunction with functional testing, in order to stimulate the failure mechanisms of defects to the point of detection. Most of these defects are caused by flawed parts and poor assembly workmanship. The stress levels of applied stimuli must be as harsh as possible to precipitate the defects without causing damage to or reducing the useful life of properly manufactured hardware.)

10 ThiLpplication of environmental stresses will accelerate the latent (or undetected) defects to become patent (detected), with functional testing required to detect failures. Functional testing can be performed either during or after the application of stress. P. The advantage of functional testing during stress application is that it allows the detection of intermittent failures. ! ,"' 4. - - i . , ,", ., )-1tCodes -,zd/or "Dist ouial loi,9I. ESS had its beginning in the space programs of the 1960s,where high reliability requirements and the absence of supportability dictated that equipment be 100% defect-free.