Composite Spar Sacrificial Surface Co-Curing
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Solution Overview
Problem
The manual installation of shims between spar flanges and skin panels in aircraft structures is a time-consuming process that compromises structural integrity and increases assembly time, as direct machining on spars is undesirable.
Innovation Solution
Composite spars are co-cured with sacrificial members on their flanges, which are then machined to conform to skin panel surfaces, eliminating the need for manual shimming and reducing assembly time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If shims are manually installed onto spars to ensure proper fit of skin panels, then gaps between skin panels and spars are mitigated, but assembly time and disassembly time increase significantly
Solution Approach 1:
The sacrificial member is co-cured with the spar flange in advance, creating a pre-integrated assembly that eliminates the need for manual shim installation during final assembly. The sacrificial member is then machined to the precise geometry needed to fit between the skin panel and spar, ensuring proper fit while reducing assembly time.
Solution Approach 2:
The sacrificial member is designed as a temporary, disposable component that is co-cured with the spar, used during assembly to achieve proper fit, and then removed. This disposable approach eliminates the need for time-consuming manual shimming while maintaining manufacturing precision.
2Manufacturing precision
If direct machining is performed on spars to ensure proper fit, then gaps between skin panels and spars are eliminated, but structural integrity of the spar is compromised
Solution Approach 1:
The sacrificial member acts as an intermediary between the spar and the skin panel. It is co-cured with the spar flange and then machined to the precise geometry needed to eliminate gaps. This allows machining to be performed on the sacrificial member rather than the structural spar, preserving spar integrity while achieving proper fit.
Solution Approach 2:
The original spar structure is segmented into two parts: the structural spar flange and the sacrificial member. The sacrificial member is co-cured to the spar flange and can be independently machined without affecting the structural integrity of the spar itself, thus separating the fitting function from the structural function.
3Manufacturing precision
If manual shimming process is used to fit skin panels to spars, then proper fit is achieved, but additional man-hours of assembly time are required
Solution Approach 1:
The sacrificial member is co-cured with the spar flange in advance, creating a pre-integrated assembly that eliminates the need for manual shim installation during final assembly. This preliminary integration significantly reduces assembly man-hours while maintaining proper fit.
Solution Approach 2:
The sacrificial member is co-cured (merged) with the spar flange to form an integrated assembly. This merging eliminates the need for separate shim installation steps, reducing assembly time and improving productivity while ensuring proper fit between skin panels and spars.
Data Source
AI summary
Composite assemblies are described that include composite spars that are co-cured with one or more sacrificial members on their flanges, forming an integrated sacrificial surface for the composite spars. In one embodiment, the composite assembly includes a composite spar having a web and flanges that project from sides of the web. The composite assembly further includes a sacrificial member of composite materials co-cured with the composite spar on an outer surface of at least one of the flanges. In addition, the sacrificial member has an outer surface that has been machined into conformance with an inner surface of at least one skin panel for an aircraft structure to form a contact surface with the at least one skin panel.