Slit-Cut Overlay Plies for Composite Core Contouring
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Solution Overview
Problem
The existing methods for forming inner mold line (IML) plies over cores in composite parts, such as aircraft wings, are laborious, time-consuming, and prone to core damage due to the manual application process, which can result in wrinkles and additional rework costs.
Innovation Solution
The method involves cutting slits in the overlay plies to allow for tension release and contouring without substantial force, enabling manual or automated forming while reducing manual touch time and core damage, using a composite structure with a base structure, a core with a non-uniform contour, and layered cover material with overlay plies and cover plies that span the slits to transfer loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If manual application of IML plies over cores is used, then the plies can be formed to cover the cores, but the process is time-consuming and laborious with high risk of core damage
Solution Approach 1:
The patent applies preliminary action by pre-cutting slits in the overlay plies before placement. This preprocessing step enables the plies to be more easily contoured to the core shape without requiring extensive manual sculpting during the laying-up process, thereby reducing labor time while maintaining placement precision
Solution Approach 2:
The patent segments the overlay plies by cutting slits through them, creating divided sections that can be independently manipulated and contoured. This segmentation allows the plies to conform to complex core geometries more easily, reducing the time and effort required for manual shaping while maintaining precise placement
2Manufacturing precision
If technicians carefully sculpt IML plies to core shape, then wrinkles can be avoided, but the process is extremely time-consuming and laborious
Solution Approach 1:
The slits are cut in advance before the plies are placed on the core. This preliminary action prepares the plies for easy contouring, allowing technicians to achieve wrinkle-free placement much faster than traditional sculpting methods would require
Solution Approach 2:
The patent changes the physical state and flexibility parameters of the overlay plies by introducing slits. This modification allows the plies to be more easily deformed and contoured to match the core shape without creating wrinkles, significantly reducing the time required for this operation
3Manufacturing precision
If technicians work out wrinkles during placement, then surface quality can be improved, but core damage and deformation risk increases
Solution Approach 1:
By pre-cutting slits in the overlay plies, the patent eliminates the need for subsequent wrinkle correction operations. The plies can be directly contoured to the core shape without requiring technicians to apply compressive forces that could damage the core, thus maintaining both surface quality and core integrity
Solution Approach 2:
The patent converts what would normally be a harmful operation (manual sculpting that risks core damage) into a beneficial process. The slits enable the plies to self-contour more easily, transforming the potentially harmful wrinkle-correction step into a simple placement operation that protects core integrity while achieving surface quality
4Productivity
If slits are cut in overlay plies, then manual touch time and core damage are reduced, but additional processing steps are required
Solution Approach 1:
The patent adds a slit-cutting step that segments the overlay plies into manageable sections. While this adds a processing step, it dramatically reduces the overall manual touch time required for contouring and placement, netting a gain in productivity despite the additional operation
Data Source
Figure 1
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Figure 3A~3C
AI summary
A composite structure (100) includes a base structure (101), a core (102) disposed on the base structure, the core having a non-uniform contour relative to the base structure, and a layered cover material (104) disposed on the base structure covering the core. The layered cover material conforms to the non-uniform contour of the core and has at least one overlay ply (105) and at least one cover ply (107). Each of the at least one overlay ply has at least one slit (106) cut through fibers of the respective overlay ply, and at least one cover ply has a shape that spans the at least one slit and is configured to transfer a load across the at least one slit.