Composite material, proposed for use in the Advanced Communications Technology Satellite (ACTS) program, utilizes a new high modulus graphite fiber as the reinforcement. A program was conducted to measure certain mechanical properties of the new fiber reinforced material and the aluminum honeycomb sandwich structure that utilizes this material in the face sheets. Properties were measured at -157, 22, and 121°C. Complete characterization of this material was not intended.
Longitudinal tensile, picture frame shear, short beam shear, and flexure tests were performed on specimens of the composite face sheet materials. Unidirectional, crossplied, and quasi-isotropic fiber composite ply layups designs that were studied using NASA's Integrated Composite Analyzer (ICAN) computer program were fabricated and tested. Flexure tests were conducted on [±60/0]s composite faced sandwich structure material. Resistance strain gages were used to measure strains in the tension, picture frame, and the sandwich flexure tests.
The results show that the sandwich flexural strength is limited by the core strength at -157°C and room temperature. The adhesive bond strength is the limiting factor at 121°C. It appears that adhesive mechanical properties are reflected in sandwich structure flexural properties when the span-to-depth ratio is of the required magnitude to allow a significant amount of shear effect on the load-deflection behavior of the sandwich beam. Most properties that were measured agree satisfactorily with the properties predicted by ICAN.