CHARACTERIZATION OF STRETCH BROKEN CARBON FIBER COMPOSITES – IM7 FIBER IN 8552 RESIN – STRETCHED AT PREPREG LEVEL

摘要

Previous work has successfully demonstrated the equivalency of stretch broken carbon fiber(SBCF) composites for a wide range of mechanical properties compared to the correspondingmaterial with continuous reinforcement.Work continued with the investigation of composites made from stretch broken (SB) IM7/8552prepregs stretched at the prepreg level in an attempt to simulate deformations that occur duringforming of complex features like beads or raised regions shaped like Brodie helmets. Theunidirectional stretching of SB IM7/8552 prepreg lay-ups was performed at elevatedtemperatures used in forming processes to allow material extension at reduced resin viscosity.This paper presents mechanical properties of composites made from SB IM7/8552 prepreg layupsstretched at the prepreg level in comparison to material made from the SB prepreg in “asmade”condition. The intent is to determine if and how the forming process changes basicmaterial properties. Select properties tested at ambient conditions include 0° tension, open holetension and compression, in-plane and short beam shear, compression after impact, and bearingresponse. Results will be discussed with particular consideration of the prepreg contractionperpendicular to the stretch direction.