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Fracture behavior of hybrid composite laminatesThe tensile fracture behavior of 15 center-notched hybrid laminates was studied. Three basic laminate groups were tested: (1) a baseline group with graphite/epoxy plies, (2) a group with the same stacking sequence but where the zero-deg plies were one or two plies of S-glass or Kevlar, and (3) a group with graphite plies but where the zero-deg plies were sandwiched between layers of perforated Mylar. Specimens were loaded linearly with time; load, far field strain, and crack opening displacement (COD) were monitored. The loading was stopped periodically and the notched region was radiographed to reveal the extent and type of damage (failure progression). Results of the tests showed that the hybrid laminates had higher fracture toughnesses than comparable all-graphite laminates. The higher fracture toughness was due primarily to the larger damage region at the ends of the slit; delamination and splitting lowered the stress concentration in the primary load-carrying plies. A linear elastic fracture analysis, which ignored delamination and splitting, underestimated the fracture toughness. For almost all of the laminates, the tests showed that the fracture toughness increased with crack length. The size of the damage region at the ends of the slit and COD measurements also increased with crack length.
Document ID
19830048518
Document Type
Conference Paper
Authors
Kennedy, J. M.
(NASA Langley Research Center Hampton, VA, United States)
Date Acquired
August 11, 2013
Publication Date
January 1, 1983
Subject Category
Composite Materials
Report/Patent Number
AIAA PAPER 83-0804
Meeting Information
Meeting: Structures, Structural Dynamics and Materials Conference
Location: Lake Tahoe, NV
Start Date: May 2, 1983
End Date: May 4, 1983
Accession Number
83A29736
Distribution Limits
Public
Copyright
Other

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