Virtual Assembly Splice Elements Eliminate Aircraft Fuselage Shims
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Solution Overview
Problem
The assembly of aircraft fuselage sections often requires shims and spacers to fill gaps caused by manufacturing variations, leading to increased weight, time, and cost due to the need for custom machining and serial processing.
Innovation Solution
A method using computer-generated models to virtually assemble fuselage sections, identify gaps, and produce splice elements with tailored profiles using solid free-form fabrication techniques, eliminating the need for shims and spacers by creating a tool insert that compensates for surface mismatches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If shims and spacers are used to fill gaps between fuselage sections, then the gaps caused by manufacturing variations are compensated, but the aircraft weight increases and manufacturing time is extended
Solution Approach 1:
The splice element's thickness parameter is varied continuously along its length to match the gap profile. Instead of using uniform thickness shims, the invention creates a splice element with non-uniform thickness that precisely compensates for the varying gap dimensions, eliminating the need for multiple discrete shim pieces and reducing overall weight.
Solution Approach 2:
The splice element is constructed using composite materials (fiber-reinforced plastic) that provide high strength-to-weight ratio. This allows the splice element to compensate for gaps while adding minimal weight compared to traditional metal shims and spacers.
2Manufacturing precision
If custom shims are machined to fill gaps, then the gaps are precisely filled, but manufacturing cost and time increase due to skilled craftsmanship requirements
Solution Approach 1:
The invention replaces the mechanical machining process with automated fiber placement and curing. Instead of skilled craftsmen manually measuring and machining each shim, the system uses automated equipment to lay up fiber-reinforced resin and cure it in a mold, eliminating the need for skilled manual labor while maintaining precision.
Solution Approach 2:
The gap profile is determined through virtual assembly before physical manufacturing. The splice element is designed and manufactured in advance based on digital models, allowing parallel processing of multiple sections and eliminating sequential measurement and machining steps.
3Measurement precision
If fuselage sections are physically fitted together to determine gap dimensions, then accurate gap measurements are obtained, but factory flow time increases due to serial processing
Solution Approach 1:
The invention uses digital copies (3D models) of fuselage sections for virtual assembly instead of physical sections. The virtual assembly process accurately determines gap dimensions without requiring physical fitting, allowing parallel manufacturing of sections and eliminating time-consuming serial assembly and disassembly operations.
Solution Approach 2:
The physical fitting and measurement process is replaced with virtual reality and computer-aided design (CAD) systems. The virtual assembly digitally positions sections and calculates gap dimensions, providing measurement accuracy without the time loss associated with physical handling and assembly.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces aircraft weight and manufacturing time by eliminating the need for custom shims and spacers, streamlining the assembly process through virtual assembly and computer-aided manufacturing of splice elements with customized profiles.
Implementation Method 1
The uncured material is produced by forming a lay-up including multiple plies of fiber reinforced resin, and drawing the lay-up against the tool insert by applying a vacuum or other force.
Implementation Method 2
introducing uncured material into the tool in contact with the insert, curing the material and removing the splice element from the tool
Data Source
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AI summary
Fuselage sections of an aircraft are joined using splice elements that compensate for gaps caused by mismatches between mating surfaces on the fuselage sections. The fuselage sections are virtually assembled using computer models that are based on non-contact measurements of as-built fuselage sections. The virtually assembled fuselage sections are used to map the gaps between the mating surfaces. The mapped gaps are used to produce tool inserts having profiles that reflect the dimensions of the gaps. The tool inserts are used to manufacture splice elements having profiles that fill the gaps when the fuselage sections are assembled and joined, thereby eliminating the need for shims and spaces to fill the gaps.