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Effects of T-tabs and large deflections in double cantilever beam specimen testsA simple strength of materials analysis was developed for a double-cantilever beam (DCB) specimen to account for geometric nonlinearity effects due to large deflections and T-tabs. A new DCB data analysis procedure was developed to include the effects of these nonlinearities. The results of the analysis were evaluated by DCB tests performed for materials having a wide range of toughnesses. The materials used in the present study were T300/5208, IM7/8551-7, and AS4/PEEK. Based on the present analysis, for a typical deflection/crack length ratio of 0.3 (for AS4/PEEK), T-tabs and large deflections cause a 15 and 3 percent error, respectively, in the computer Mode I strain energy release rate. Design guidelines for DCB specimen thickness and T-tab height were also developed in order to keep errors due to these nonlinearities within 2 percent. Based on the test results, for both hinged and tabbed specimens, the effects of large deflection on the Mode I fracture toughness (G sub Ic) were almost negligible (less than 1 percent) in the case of T300/5208 and IM7/8551-7; however, AS4/PEEK showed a 2 to 3 percent effect. The effects of T-tabs G sub Ic were more significant for all the materials with T300/5208 showing a 5 percent error, IM7/8551-7 a 15 percent error, and, AS4/PEEK a 20 percent error.
Document ID
19920056385
Acquisition Source
Legacy CDMS
Document Type
Conference Proceedings
Authors
Naik, Rajiv A.
(Analytical Services and Materials, Inc. Hampton, VA, United States)
Crews, John H., Jr.
(NASA Langley Research Center Hampton, VA, United States)
Shivakumar, Kunigal N.
(Analytical Services and Materials, Inc. Hampton, VA, United States)
Date Acquired
August 15, 2013
Publication Date
January 1, 1991
Subject Category
Structural Mechanics
Accession Number
92A39009
Distribution Limits
Public
Copyright
Other

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