Mechanical Property Characterization of Intraply Hybrid Composites

: An investigation was conducted to characterize the mechanical properties of intraply hybrids made from graphite fiber/epoxy matrix (primary composites) hybridized with varying amounts of secondary composites made from S-glass or Kevlar 49 fibers. The tests were conducted using thin laminates having the same thickness. The specimens for these tests were instrumented with strain gages to determine stress-strain behavior. The results show that the mechanical properties of intraply hybrid composites can be measured using available test methods such as the ten-degree off-axis method for intralaminar shear, and conventional test methods for tensile, flexure, and Izod impact properties. Intraply hybrids have linear stress-strain curves to fracture for longitudinal tension and nonlinear stress-strain curves for intralaminar shear. The results also showed that combinations of high modulus graphite/S-glass/epoxy matrix composites exist which yield intraply hybrid laminates with the "best" balanced properties, for example: 100-percent increase in impact resistance, 35-percent increase in tensile and flexural strengths, with no reduction in modulus compared to graphite fiber/epoxy matrix composites. in addition, the results showed that the translation efficiency of mechanical properties from the consistituent composites to intraply hybrids may be assessed using a simple equation. (MM)