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Redesign of the mixed-mode bending test for delamination toughnessThe mixed-mode bending (MMB) test uses a lever to simultaneously apply mode I and mode II loading to a split-beam specimen. A nonlinear, iterative analysis that accurately predicts the measured load-displacement response and the strain energy release rate, G, of an MMB test, has shown that the errors in G calculated using linear theory can be quite large. The nonlinear analysis was used as a guide in redesigning the MMB apparatus. With the redesigned apparatus, loads are applied through a roller attached to the lever and loaded just above the midplane of the test specimen. The redesigned MMB apparatus has geometric nonlinearity errors of less than 3 percent, even for materials substantially tougher than APC2 (AS4/PEEK). This apparatus was demonstrated by measuring the mixed-mode delamination fracture toughness of APC2. The data from the redesigned MMB apparatus were analyzed with a linear analysis which yielded results similar to those found with the original apparatus and the nonlinear analysis.
Document ID
19920050236
Document Type
Conference Paper
Authors
Reeder, J. R.
(NASA Langley Research Center Hampton, VA, United States)
Crews, J. H., Jr.
(NASA Langley Research Center Hampton, VA, United States)
Date Acquired
August 15, 2013
Publication Date
January 1, 1991
Subject Category
Structural Mechanics
Meeting Information
International Conference on Composite Materials (ICCM/8)(Honolulu, HI)
Distribution Limits
Public
Copyright
Other
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