Bonded Splice Joint for Aircraft Side-of-Body Assembly
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Solution Overview
Problem
Traditional aircraft side-of-body joints are heavy and costly due to the use of many mechanical fasteners, which can experience fatigue and require frequent maintenance, and they do not allow for a continuous skin section, increasing operational costs and weight.
Innovation Solution
A bonded side-of-body joint assembly using t-shaped stringers and cruciform fittings with a central rib attachment member, where the stringer attachment portions of the t-shaped fitting extensions are inserted into the lengthwise gap of the t-shaped stringers, allowing a continuous skin section to be coupled, reducing the need for multiple skin sections and fasteners.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional mechanical joints with bolts and ribs are used to join wing panels to fuselage, then the joint can meet load requirements and provide structural strength, but the joint becomes very heavy and increases operational cost
Solution Approach 1:
The patent replaces traditional mechanical fastening systems (bolts, ribs) with a bonded joint system using adhesive. The bonding members are attached to the skin sections and stringers, creating a chemical bond instead of mechanical connection. This substitution eliminates the need for heavy mechanical fasteners while maintaining joint strength through adhesive bonding across the joint interface.
Solution Approach 2:
The patent employs composite construction by combining different materials - skin sections, stringers, and bonding members - joined through adhesive bonding. This creates a composite joint structure that leverages the properties of each material to achieve high strength-to-weight ratio, reducing overall joint weight while maintaining structural integrity.
2Strength
If traditional mechanical joints with multiple bolts and fastening devices are used, then the joint can meet bearing allowable requirements, but the production cost increases due to separate fabrication and assembly of multiple parts
Solution Approach 1:
The patent merges multiple separate components (skin sections, stringers, bonding members) into an integrated bonded joint assembly. The bonding members span across the joint line and bond multiple skin sections and stringers together in a single manufacturing step, eliminating the need for separate fabrication and assembly of multiple mechanical fasteners and their associated operations.
Solution Approach 2:
By replacing the mechanical fastening system with adhesive bonding, the patent simplifies the manufacturing process. Instead of requiring precise hole alignment, bolt insertion, and tightening operations for multiple fasteners, the bonded joint can be manufactured more efficiently with reduced labor and equipment requirements.
3Strength
If traditional bolted joints are used to connect aerodynamic structures, then the joint can provide initial structural connection, but the joint experiences fatigue over time requiring periodic inspection, maintenance and replacement
Solution Approach 1:
The patent replaces mechanical fasteners that are susceptible to fatigue from cyclic loading with adhesive bonding. The bonded joint distributes stresses more uniformly across the joint interface, reducing stress concentrations at fastener holes and minimizing fatigue initiation sites. This improves long-term reliability and reduces maintenance requirements.
Solution Approach 2:
The patent changes the fundamental connection parameter from mechanical (bolted) to chemical (bonded). This parameter change transforms the joint's response to cyclic loading, as adhesive bonds do not have the same fatigue failure modes as mechanical fasteners, thereby improving durability and reducing inspection frequency.
4Ease of manufacture
If discontinuous skin sections joined at side-of-body rib are used, then the joint can be constructed with manageable panel sizes, but the joint requires additional fasteners and increases weight and operational cost
Solution Approach 1:
The patent replaces the mechanical fastening system required for joining discontinuous skin sections with adhesive bonding. The bonding members attached to the skin sections and stringers create a continuous bonded joint that eliminates the need for additional bolts and fasteners at the side-of-body rib location, reducing joint weight while maintaining constructability with manageable panel sizes.
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
An aircraft structure, comprising an aircraft side-of-body joint assembly which may have first and second stringers (208), each having a vertical stringer portion (209) defining a lengthwise gap (408). The embodiment may include a cruciform fitting (206) having a central rib attachment member (304) and first and second extensions (302) extending in opposite directions from said central rib attachment member (304). Stringer attachment portions (308) extending up from said first and second extensions (302) are inserted into the lengthwise gaps of the first and second stringer portions (208), respectively. The rib attachment member may be attached to a side-of-body rib.