Failure Criteria for Particulate Reinforced Glassy Polymers
MONSANTO RESEARCH CORP ST LOUIS MO
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A theory for predicting the stress-strain behavior of glassy polymeric composites has been developed. Irreversible deformation is assumed to be a combination of nucleation of submicroscopic defects at stress inhomogeneities and their subsequent growth to macroscopic dimensions. The failure of the material is determined by a competition between the dilational strain associated with microcavitation, causing the stress-strain curve to deflect from linearity, and the linear growth of stress concentrators that are potential sources for brittle failure. Yielding occurs when there is sufficient microcavitation prior to the formation of critical flaws. It has been shown that the addition of particulate filler to a polyphenylene oxide polymer increases the rate of nucleation of crazes relative to their rate of growth, thereby promoting a greater tendency for macroscopic yielding. It was also shown that the composite stress-strain behavior can be described in terms of constituent properties and volume fraction of filler.
- Laminates and Composite Materials