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Validation of bonded composite doubler technology through application oriented structural testingOne of the major thrusts established under the FAA's National Aging Aircraft Research Program is to foster new technologies associated with civil aircraft maintenance. Recent DOD and other government developments in the use of bonded composite patches on metal structures has supported the need for research and validation of such doubler applications on U.S. certificated airplanes. Composite patching is a rapidly maturing technology which shows promise of cost savings on aging aircraft. Sandia Labs is conducting a proof-of-concept project with Delta Air Lines, Lockheed Martin, Textron, and the FAA which seeks to remove any remaining obstacles to the approved use of composite doublers. By focusing on a specific commercial aircraft application - reinforcement of the L-1011 door frame - and encompassing all 'cradle-to-grave' tasks such as design, analysis, installation, and inspection, this program is designed to prove the capabilities of composite doublers. This paper reports on a series of structural tests which have been conducted on coupons and subsize test articles. Tension-tension fatigue and residual strength tests attempted to grow engineered flaws in coupons with composite doublers bonded to aluminum skin. Also, structures which modeled key aspects of the door corner installation were subjected to extreme tension, shear, and bending loads. In this manner it was possible to study strain fields in and around the Lockheed-designed composite doubler using realistic aircraft load scenarios and to assess the potential for interply delaminations and disbonds between the aluminum and the laminate. The data acquired was also used to validate finite element models (FEM) and associated Damage Tolerance Analyses.
Document ID
19960052223
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Roach, Dennis
(Sandia National Labs. Albuquerque, NM United States)
Graf, Darin
(Sandia National Labs. Albuquerque, NM United States)
Date Acquired
August 17, 2013
Publication Date
January 1, 1996
Subject Category
Composite Materials
Report/Patent Number
CONF-960847-1
SAND-96-1860C
DE96-013246
Meeting Information
Meeting: Fibrous Composites in Structural Design
Location: Fort Worth, TX
Country: United States
Start Date: August 26, 1996
End Date: August 29, 1996
Sponsors: Federal Aviation Administration, Department of Defense, NASA Headquarters
Accession Number
96N35430
Funding Number(s)
CONTRACT_GRANT: DE-AC04-94AL-85000
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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