Strain intensity factor approach for predicting the strength of continuously reinforced metal matrix compositesA method was previously developed to predict the fracture toughness (stress intensity factor at failure) of composites in terms of the elastic constants and the tensile failing strain of the fibers. The method was applied to boron/aluminum composites made with various proportions of 0 deg and +/- 45 deg plies. Predicted values of fracture toughness were in gross error because widespread yielding of the aluminum matrix made the compliance very nonlinear. An alternate method was develolped to predict the strain intensity factor at failure rather than the stress intensity factor because the singular strain field was not affected by yielding as much as the stress field. Far-field strains at failure were calculated from the strain intensity factor, and then strengths were calculated from the far-field strains using uniaxial stress-strain curves. The predicted strengths were in good agreement with experimental values, even for the very nonlinear laminates that contained only +/- 45 deg plies. This approach should be valid for other metal matrix composites that have continuous fibers.
Document ID
19900044406
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Poe, Clarence C., Jr. (NASA Langley Research Center Hampton, VA, United States)
Date Acquired
August 14, 2013
Publication Date
January 1, 1989
Subject Category
Composite Materials
Meeting Information
Meeting: Symposium on Metal Matrix Composites: Testing, Analysis, and Failure Modes