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Fatigue Life Analysis of Tapered Hybrid Composite FlexbeamsNonlinear-tapered flexbeam laminates from a full-size composite helicopter rotor hub flexbeam were tested under combined constant axial tension and cyclic bending loads. The two different graphite/glass hybrid configurations tested under cyclic loading failed by delamination in the tapered region. A 2-D finite element model was developed which closely approximated the flexbeam geometry, boundary conditions, and loading. The analysis results from two geometrically nonlinear finite element codes, ANSYS and ABAQUS, are presented and compared. Strain energy release rates (G) obtained from the above codes using the virtual crack closure technique (VCCT) at a resin crack location in the flexbeams are presented for both hybrid material types. These results compare well with each other and suggest that the initial delamination growth from the resin crack toward the thick region of the flexbeam is strongly mode II. The peak calculated G values were used with material characterization data to calculate fatigue life curves and compared with test data. A curve relating maximum surface strain to number of loading cycles at delamination onset compared reasonably well with the test results.
Document ID
20040085706
Acquisition Source
Langley Research Center
Document Type
Other
Authors
Murri, Gretchen B.
(Army Research Lab. Hampton, VA, United States)
Schaff, Jeffery R.
(United Technologies Research Center East Hartford, CT, United States)
Dobyns, Alan L.
(Sikorsky Aircraft Stratford, CT, United States)
Date Acquired
August 21, 2013
Publication Date
January 1, 2002
Subject Category
Composite Materials
Distribution Limits
Public
Copyright
Public Use Permitted.
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