Accurate Characterization of Composite Strength through Empirical and Progressive Damage Methods

Bau, H., Hoyt, D.M.

NSE Composites Phase I Final Report to USAF for STTR AF96T009, April, 1997.

Structural laminated composites are used extensively in new aircraft applications. Expensive large test programs are conducted to generate composite strength allowables because existing analytical methods are not accurate. These existing large test programs have never been comprehensively reviewed together.

NSE Composites (NSE) and Stanford University are teamed to accurately characterize laminated composites strength behavior. NSE will conduct a comprehensive evaluation of the existing test databases and will reduce the data into empirical characteristic equations. Stanford will analytically predict strength with their existing progressive damage models. The empirical characteristic equations will be used to validate and/or improve the progressive damage models.

In Phase I, an empirical characteristic equation will be generated and used to evaluate progressive damage predictions for a selected test configuration over 4 material systems. Phase II will focus on additional test configurations, material systems, and an overall validation of the progressive damage method.

This STTR will result in empirical characteristic equations and validated progressive damage models. These will provide new insight into composite strength behavior and will substantially reduce the cost of generating composites structural allowables. Initial commercialization will be aimed towards new composite allowables programs for government and commercial aircraft.