Nonlinear Finite Element Analysis of a Composite Non-Cylindrical Pressurized Aircraft Fuselage Structure

Abstract

The Environmentally Responsible Aviation Project aims to develop aircraft technologies enabling significant fuel burn and community noise reductions. Small incremental changes to the conventional metallic alloy-based 'tube and wing' configuration are not sufficient to achieve the desired metrics. One of the airframe concepts that might dramatically improve aircraft performance is a composite-based hybrid wing body configuration. Such a concept, however, presents inherent challenges stemming from, among other factors, the necessity to transfer wing loads through the entire center fuselage section which accommodates a pressurized cabin confined by flat or nearly flat panels. This paper discusses a nonlinear finite element analysis of a large-scale test article being developed to demonstrate that the Pultruded Rod Stitched Efficient Unitized Structure concept can meet these challenging demands of the next generation airframes. There are specific reasons why geometrically nonlinear analysis may be warranted for the hybrid wing body flat panel structure. In general, for sufficiently high internal pressure and/or mechanical loading, energy related to the in-plane strain may become significant relative to the bending strain energy, particularly in thin-walled areas such as the minimum gage skin extensively used in the structure under analysis. To account for this effect, a geometrically nonlinear strain-displacement relationship is needed to properly couple large out-of-plane and in-plane deformations. Depending on the loading, this nonlinear coupling mechanism manifests itself in a distinct manner in compression-and tension-dominated sections of the structure. Under significant compression, nonlinear analysis is needed to accurately predict loss of stability and postbuckled deformation. Under significant tension, the nonlinear effects account for suppression of the out-of-plane deformation due to in-plane stretching. By comparing the present results with the previously published preliminary linear analysis, it is demonstrated in the present paper that neglecting nonlinear effects for the structure and loads of interest can lead to appreciable loss in analysis fidelity.

Composite Structure Modeling and Analysis of Advanced Aircraft Fuselage Concepts

“…These complex joints would require local corner braces or gusset plates in order to preclude local failure. In the actual test article FEM modeling and analysis 16 , the skin is reinforced gradually with layups from 2 to 10 stacks of woven stitched composite, and are seamlessly integrated into the flanges for attachment with side walls or ribs. Table 1 shows initial breakdown of the structural weight components for the HWB multi-bay fuselage section.…”

“…This conceptual model is similar in geometry, compared to the engineering analysis of the test article described in Ref. 16, but many construction features are simplified in order to perform multiple design alternatives studies. This 70% scale HWB multi-bay box model is 360 inch wide in the spanwise direction with a height of 162 in.…”

“…Structural analysis of the HWB conceptual vehicles for 100, 200, 300, and 400-passengers were presented by Gern [14][15] , in order to optimize the full vehicle structural weight at critical design load conditions. The most recent structural analysis of the HWB multi-bay fuselage section test article was presented by Przekop 16 . An integrated multi-bay fuselage and bulkhead finite element models (FEM) with flat PRSEUS panels were developed and analyzed for an independent case study and weight estimation 13,17 .…”

“…Many novel structural concepts such as the ribbeddouble-shell, multi-bubble stiffened shell, thick composite sandwich shell, and recently the Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) construction have been studied under the NASA Environmentally Responsible Aviation (ERA) research project [6][7][8][9][10][11][12][13][14][15][16][17] in collaboration with the Boeing Company. Figure 1 shows a schematic diagram of the PRSEUS technology development, starting with test coupons, flat and curved PRSEUS panels and progressing towards a HWB fuselage section construction at the Boeing Company and follow-up testing under way at NASA Langley Research Center.…”

Vibroacoustic Tailoring of a Rod-Stiffened Composite Fuselage Panel with Multidisciplinary Considerations

“…The PRSEUS concept has been shown to meet the static performance requirements of the HWB flat-sided pressure cabin design while also bearing significant wing loads [5]. However, due to the HWB vehicle configuration and PRSEUS properties, excessive interior noise is a concern.…”