Influence of fiber coating and interphase on the design of polymeric composite strength-analytical predictions

摘要

The paper discusses the effects of tough compliant thermoplastic fiber coatings on the composite strength under tension, compression, shear, transverse, and thermal loading. Various strength prediction models are reviewed and used to estimate the influence of the compliant fiber coating on the strength values. Parameter studies for various relative coating stiffness and thickness are performed. It is found that some models predict that a compliant fiber coating may reduce the overall static strength of the composite. However, a more detailed analysis points out that such reduction may be compensated by the more subtle improvements induced by the coating in the statistical strength of the processed fibers and in the reduction of stress concentration around the broken fiber through spreading of the effect over a larger number of adjacenet fibers. Reduction in residual stresses due to thermal differences between processing and operating temperatures are also predicted.