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
Study of sandwich effect on nanoclay modified polyester resin GFR face sheet laminates
Abstract This paper investigates the influence of nanoclay content on flexural, impact and water absorption properties of Fibre Reinforced Polymer (FRP) and FRP face sheet sandwich laminates with polystyrene foam core. Four different combinations of FRP composites (0, 2, 4 and 6 wt% of nano clay) have been prepared by hand lay-up manufacturing techniques (HL) and they have been investigated for the same to obtain the best combination. Further, based on the best combination obtained, two different (0 and 4 wt%) sandwich laminates are prepared to make relative comparison among various laminates. X-ray diffraction (XRD) results have been obtained from the FRP samples, where the nanoclay has indicated that, the mode of dispersion and intergallery spacing of the layered clay. Scanning electron microscopy (SEM) has given morphological picture of the FRP fracture samples. The results of the study show that, the flexural, impact and water absorption properties of the nano polyester sandwich laminate have been greatly increased at 4% of nanoclay loading.
Ground Fault Protection for Electric Utility Generating Station Medium Voltage Auxiliary Power Systems
Most generating station designs have medium voltage auxiliary power systems with low resistance grounded neutrals.1 In order to provide even higher reliability, the auxiliary power distribution system configurations supply increasingly redundant process equipment.