Circumferential Stringers for Fuselage Splicing and Load Distribution
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Solution Overview
Problem
The conventional method of using longitudinally oriented stringers in aircraft fuselages is labor-intensive and prone to structural failures due to delamination and fatigue, requiring splice plates and fasteners that increase weight and cost.
Innovation Solution
The use of vertically-oriented circumferential stringers that encircle the fuselage, reducing the need for longitudinal splicing and allowing wing spars to attach directly to the fuselage, thereby distributing loads and reducing manufacturing time and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional longitudinal stringers are used in fuselage construction, then the fuselage can provide strength and stiffening characteristics, but the splicing operation becomes tedious and labor-intensive when joining fuselage sections
Solution Approach 1:
The patent inverts the conventional longitudinal stringer orientation by using circumferential stringers that wrap around the fuselage instead of running lengthwise. This inversion eliminates the need for splicing operations when joining fuselage sections, as the circumferential stringers continue uninterrupted around the joined sections, thereby resolving the labor-intensive splicing problem while maintaining structural strength.
Solution Approach 2:
The patent transitions from the conventional one-dimensional longitudinal stringer arrangement to a two-dimensional circumferential configuration. By wrapping stringers around the fuselage in circumferential loops rather than extending them linearly along the fuselage length, the design eliminates discontinuities at section joints and removes the need for splicing operations.
2Reliability
If splice plates and fasteners are used to prevent structural failures at stringer splices, then structural reliability improves, but aircraft weight and cost significantly increase
Solution Approach 1:
By inverting the stringer orientation from longitudinal to circumferential, the patent eliminates the vulnerable splice locations that would require reinforcement. The circumferential stringers create continuous load paths around the fuselage that naturally distribute stresses without concentration points, thereby maintaining structural reliability without needing additional splice plates and fasteners that would increase weight.
Solution Approach 2:
The patent extracts and eliminates the splicing operation entirely from the fuselage construction process by using circumferential stringers. This removal of the splicing step eliminates the need for associated reinforcement elements like splice plates and fasteners, thereby reducing aircraft weight while maintaining structural integrity through the continuous circumferential stringer configuration.
3Strength
If conventional longitudinal stringers are used, then strength characteristics are provided, but delamination or structural failure may occur due to common loads and moments during flight
Solution Approach 1:
The patent inverts the stringer orientation to circumferential configuration, which fundamentally changes the stress distribution pattern. Instead of longitudinal stringers that experience concentrated loads at splice points, the circumferential stringers distribute loads uniformly around the fuselage circumference, eliminating the delamination and fatigue issues that arise from repeated stress cycles at discrete splice locations.
Solution Approach 2:
The patent changes the geometric parameter of stringer orientation from longitudinal to circumferential. This parameter change transforms the stress distribution characteristics, converting concentrated stresses at splice points into distributed stresses around the fuselage circumference, thereby enhancing resistance to delamination and fatigue failure under common flight loads and moments.
Data Source
Figure 1
Figure 2~2B
Figure 3~3B
AI summary
Apparatus and methods provide for the reinforcement of various components of an aircraft utilizing vertically-oriented circumferential stringers (112). According to embodiments described herein, barrel skin of an aircraft fuselage may be reinforced using stringers (112) that are vertically-oriented and circumferential. According to additional embodiments, the wing stringers (116) of a wing can be aligned with circumferential stringers. According to further embodiments, the wing may also have one or more wing spars (610) having an elliptical aperture (614). The shape of the elliptical may be configured for attachment to a fuselage so that an outer surface of the aperture is disposed proximate to an inner surface of the fuselage.