Testing and analysis of Stretch Broken Carbon Fiber (SBCF) stiffened panels subjected to in-plane shear loading

Aircraft structure weight is an important design driver in aerospace applications. The utility of advanced composites in this regard has spurred implementation on a broad spectrum of aircraft designs. Further structural efficiencies might be gained if innovative integral stiffening concepts could be produced economically. Strong coupling between processing cost and part geometry, imposed by fiber inextensibility, has inhibited such advances. Stretch Broken Carbon Fiber (SBCF) materials substantially relieve these constraints, and complex part geometries are now feasible, with cost effective automated forming technologies, to an expanded degree. Critical load conditions driving integrally stiffened component design include inward and outward pressure, contact/impact loads, in plane tension and compression and pure shear. Many integrally stiffened panel concepts are appropriate for shear or compressive buckling critical components of airframes. In this paper detailed results of SBCF material panel shear tests are presented for two concepts. A panel representative of established bead stiffened designs is compared to a new innovative concept developed by Aurora Flight Sciences. Analyses were performed to determine displacements and strain distributions and these were compared to strain gage data from shear tests. The paper shows that, with appropriate modeling assumptions, the measured trends can be properly represented and a viable design optimization approach is therefore established.