CHARACTERIZATION OF STRETCHED BROKEN CARBON FIBER (SBCF) MATERIAL FORMS

摘要

Lightweight, polymer matrix composites (PMC's) are an enabling material for aircraft providing a combination of high stiffness to weight ratio and improved corrosion and fatigue resistance. PMC's, though, are expensive to manufacture. Considerable savings could be achieved through application of lower cost composites forming, compression molding, or other automated fabrication processes. The limited formability of continuous fiber PMC's, though, has restricted their use in these automated manufacturing techniques. Recently Hexcel Corp. has developed an improved aligned, discontinuous carbon fiber system, designated Stretch Broken Carbon Fiber (SBCF), that has the combined properties of improved formability without the large mechanical performance knock-downs typical of random, discontinuous systems. This paper presents initial stretch test results for both uni-directional & fabric (prepreg) forms of IM7/M73 and AS4/M73 SBCF materials. The study evaluates the influence of forming rate and temperature, fiber break length distribution versus sample gage length, resin type, and fiber sizing effects on uncured SBCF forms. Initial mechanical properties of SBCF based composites are also presented. Results indicate the minimum stretch load for different forms of SBCF material varies depending on the material forming process parameters. Implications of these results for manufacturing parts with SBCF via composites diaphragm forming are also discussed.