Effect of impact damage and open holes on the compression strength of tough resin/high strain fiber laminates

Structural damage and design-based inclusions such as cutouts can reduce significantly the strength of graphite-epoxy laminates. One composite mechanics research activity at the Langley Research Center is to assess and improve the performance of composite structures in strength are common to both tension and compression loaded laminates; however, the problem associated with compression performance is the most illusive to solve. Compression failure involves both shear crippling and delamination modes. Several graphite-epoxy material systems proposed for improved damage-tolerance were studied. Material parameters included both tough resin formulations and high strain fibers.