Response of Composite Fuselage Sandwich Side Panels Subjected to Internal Pressure and Axial Tension
The results from an experimental and analytical study of two composite sandwich fuselage side panels for a transport aircraft are presented. Each panel has two window cutouts and three frames and utilizes a distinctly different structural concept. These panels have been evaluated with internal pressure loads that generate biaxial tension loading conditions. Design limit load and design ultimate load tests have been performed on both panels. One of the sandwich panels was tested with the middle frame removed to demonstrate the suitability of this two-frame design for supporting the prescribed biaxial loading conditions with twice the initial frame spacing of 20 inches. A damage tolerance study was conducted on the two-frame panel by cutting a notch in the panel that originates at the edge of a cutout and extends in the panel hoop direction through the window-belt area. This panel with a notch was tested in a combined-load condition to demonstrate the structural damage tolerance at the design limit load condition. Both the sandwich panel designs successfully satisfied all desired load requirements in the experimental part of the study, and experimental results from the two-frame panel with and without damage are fully explained by the analytical results. The results of this study suggest that there is potential for using sandwich structural concepts with greater than the usual 20-in.-wide frame spacing to further reduce aircraft fuselage structural weight. in the airframe industry. Structural trade studies for
Numerical Modelling of a Composite Fuselage Manufactured by Liquid Resin Infusion
FUSCOMP (FUSelage COMPosite) is a Research & Development program which has received the label from the Aerospace Valley competitiveness cluster. It will lead to a test of a composite fuselage demonstrator manufactured by the Liquid Resin Infusion (LRI) process. LRI is based on the moulding of high performance composite parts by infusing liquid resin on dry fibers instead of prepreg fabrics. The study of this proof of concept is based on the TBM 850 airframe, a pressurized business turboprop aircraft currently produced by DAHER-SOCATA. Technical achievements will concern numerical methods and finite elements analysis to be used for the modelling of this aircraft composite fuselage structure. Actual industrial projects face composite integrated structure issues as a number of structures (stiffeners,...) are more and more integrated onto the skins of aircraft fuselage. Indeed the main benefit of LRI is to reduce assembly steps which lead to cycle time gain and thus cost reduction. In particular, infusing components and sub-components at the same time avoids riveting parts altogether. However it is necessary to validate the dimensioning of the studied composite structure.
Advanced composite fuselage technology
Boeing's ATCAS program has completed its third year and continues to progress towards a goal to demonstrate composite fuselage technology with cost and weight advantages over aluminum. Work on this program is performed by an integrated team that includes several groups within The Boeing Company, industrial and university subcontractors, and technical support from NASA. During the course of the program, the ATCAS team has continued to perform a critical review of composite developments by recognizing advances in metal fuselage technology. Despite recent material, structural design, and manufacturing advancements for metals, polymeric matrix composite designs studied in ATCAS still project significant cost and weight advantages for future applications. A critical path to demonstrating technology readiness for composite transport fuselage structures was created to summarize ATCAS tasks for Phases A, B, and C. This includes a global schedule and list of technical issues which will be addressed throughout the course of studies. Work performed in ATCAS since the last ACT conference is also summarized. Most activities relate to crown quadrant manufacturing scaleup and performance verification. The former was highlighted by fabricating a curved, 7 ft. by 10 ft. panel, with cocured hat-stiffeners and cobonded J-frames. In building to this scale, process developments were achieved for tow-placed skins, drape formed stiffeners, braided/RTM frames, and panel cure tooling. Over 700 tests and supporting analyses have been performed for crown material and design evaluation, including structural tests that demonstrated limit load requirements for severed stiffener/skin failsafe damage conditions. Analysis of tests for tow-placed hybrid laminates with large damage indicates a tensile fracture toughness that is higher than that observed for advanced aluminum alloys. Additional recent ATCAS achievements include crown supporting technology, keel quadrant design evaluation, and sandwich process development.