Segmented Composite Spar Assembly to Prevent Curing Wrinkles
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Solution Overview
Problem
Existing manufacturing processes for composite spars face challenges in forming tubular shapes without wrinkles or defects due to non-symmetric shapes and woven composite materials, particularly during the curing process where differences in ply orientations cause wrinkling and bunching.
Innovation Solution
The process involves dividing the tubular composite assembly into multiple cured composite assemblies, each with a sloped axial edge, which are bonded together using adhesive or fasteners, and covered with composite plies that are co-cured to form a tubular structure, allowing for optimized mold selection and reduced defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a single tubular composite assembly is formed during layup, then the structure provides continuous spinal support, but the non-symmetric shape and woven composite materials cause wrinkling and bunching during curing
Solution Approach 1:
The tubular composite assembly is divided into multiple separate composite assemblies (first, second, third assemblies) that are cured independently and then joined together. This segmentation eliminates the finger-trapping effect and wrinkling that occur when attempting to cure a complete tubular structure in one piece, while still providing the required structural support when assembled.
2Manufacturing precision
If multiple composite assemblies are cured separately and then joined, then manufacturing defects are reduced, but the assembly process becomes more complex
Solution Approach 1:
The composite assemblies are pre-cured in simpler, non-tubular configurations before final assembly. This preliminary curing action allows each component to be manufactured with high precision without the complexity of forming and curing a complete tubular structure, and the pre-cured components are then joined using standard fastening methods.
3Shape
If a precision mold is used to form the tubular shape during curing, then the desired shape is achieved, but the process time and cost increase
Solution Approach 1:
Instead of using a complex precision mold to form the complete tubular shape in one curing cycle, the structure is segmented into multiple components that can be cured in simpler molds or fixtures. This reduces the time and cost associated with precision molding while achieving the same final tubular geometry through assembly of the segmented components.
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 manufacturing defects and time, enhances quality, and provides cost savings by simplifying the layup process and eliminating the finger-trapping effect, while enabling faster production rates.
Implementation Method 1
An adhesive agent may be applied on the axial edge for bonding two cured composite assemblies
Implementation Method 2
The cure can be accelerated by applying heat and pressure to the composite layup
Implementation Method 3
an inflatable bladder may be disposed within the uncured spar and expanded to help compact the layers of preformed composite material and remove any excess air bubbles or other voids
Data Source
AI summary
Embodiments are directed to systems and methods for two or more cured composite assemblies that are bonded together to form a tubular composite structure, wherein each of the cured composite assemblies do not have a tubular shape. The tubular composite structure may form a spar for an aerodynamic component, for example. The two or more cured composite assemblies may comprise carbon or fiberglass composite materials or a combination of materials. Each of the cured composite assemblies may further comprise axial edges that are configured to be bonded to another of the cured composite assemblies, wherein the axial edges have a sloped shape. An adhesive agent may be applied on the axial edges for bonding two cured composite assemblies. Alternatively, or additionally, one or more fasteners may be used to attach the axial edges of at least two cured composite assemblies.