Structural Configuration Systems Analysis for Advanced Aircraft Fuselage Concepts

Abstract

Structural configuration analysis of an advanced aircraft fuselage concept is investigated. This concept is characterized by a double-bubble section fuselage with rear mounted engines. Based on lessons learned from structural systems analysis of unconventional aircraft, high-fidelity finite-element models (FEM) are developed for evaluating structural performance of three double-bubble section configurations. Structural sizing and stress analysis are applied for design improvement and weight reduction. Among the three double-bubble configurations, the double-D cross-section fuselage design was found to have a relatively lower structural weight. The structural FEM weights of these three double-bubble fuselage section concepts are also compared with several cylindrical fuselage models. Since these fuselage concepts are different in size, shape and material, the fuselage structural FEM weights are normalized by the corresponding passenger floor area for a relative comparison. This structural systems analysis indicates that an advanced composite double-D section fuselage may have a relative structural weight ratio advantage over a conventional aluminum fuselage. Ten commercial and conceptual aircraft fuselage structural weight estimates, which are empirically derived from the corresponding maximum takeoff gross weight, are also presented and compared with the FEMbased estimates for possible correlation. A conceptual full vehicle FEM model with a double-D fuselage is also developed for preliminary structural analysis and weight estimation.Nomenclature g = acceleration due to gravity. psi = pounds per square inch. P = cabin internal pressure of 9.2 psi (2P = 18.4 psi). R = radius of cylindrical fuselage. t = plate or shell skin thickness.

Structural Configuration Analysis of Advanced Flight Vehicle Concepts with Distributed Hybrid-Electric Propulsion

“…Figure 5 shows deflection and stress distribution from initial finite element analysis of the first inboard fan duct with an internal design pressure of 2 psi and advanced composite material properties. 12 The displacement analysis shows 1.13 inch deformation near the rectangular outlets, which required additional reinforcement supports in addition to lengthwise ribs. The circular mid-section of the ducts is reinforced with two blade containment hoops to reduce overall stresses, which are generally below 50,000 psi.…”

“…Predicting the weight requires higher order analysis such as the structural finite element analysis. Based on lessons learned from previous structural analysis of unconventional concepts, such as the hybrid-wing-body fuselage section 11 and large doublebubble fuselage section, 12 high-fidelity finite element models (FEM) of the aircraft wing with embedded electric fans 2 American Institute of Aeronautics and Astronautics have been developed. Wing structure and propulsor integration is investigated to seek an efficient design.…”

“…Much of the past work has focused on unconventional fuselages structures. Figures 1a-1d show finite element models of a hybrid-wing-body vehicle fuselage section, 11 a conventional cylindrical section fuselage, a comparable ND8 double-bubble and double-D section fuselage section, 12 and a double-bubble type vehicle. Note that in evaluating new structural concepts it is important to establish a relevant baseline, such as the cylindrical fuselage shown in Figure 1b.…”

Extension of HCDstruct for Transonic Aeroservoelastic Analysis of Unconventional Aircraft Concepts

“…Enabled by the double-bubble internal structure, the widened fuselage offers additional lift and additional interior cabin space over conventional tubular fuselages. Detailed analysis and systems-level trades on the fuselage structural design focused on concepts ranging from cusped, double-bubble structural architectures to smoothly contouring, oval structural architectures including centerline tension members and aerodynamic fairings, 19 which are inline with the modeling approach taken by HCDstruct.…”