Composite Rotor Blade Repair Structure and Method
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Solution Overview
Problem
Composite rotor blades, particularly those used in helicopters, face challenges in cost and time-consuming repair processes, especially in the trailing edge areas where damage such as scratches or delaminations require extensive procedures like stripping and rebuilding.
Innovation Solution
A method involving the application of a filler material to the damaged area, followed by a patch assembly comprising precured laminate packs and overwrap plies, which are cured to match the original rotor blade's stiffness and structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If extensive repair procedures like stripping and rebuilding are performed on damaged composite rotor blades, then structural integrity is restored, but repair time and costs increase significantly
Solution Approach 1:
The repair method performs preliminary preparation by cleaning and roughening the damaged area before applying filler material and patches. This preliminary action creates optimal surface conditions that enable faster subsequent repair steps while ensuring proper adhesion and structural integrity of the repair components.
Solution Approach 2:
The repair structure is segmented into distinct functional components: filler material for voids, multiple laminate packs for structural restoration, and overwrap plies for surface completion. This segmentation allows each component to be optimized independently and applied in a systematic sequence, reducing overall repair time while maintaining integrity.
2Reliability
If extensive repair procedures like stripping and rebuilding are performed on damaged composite rotor blades, then structural integrity is restored, but repair costs increase significantly
Solution Approach 1:
Instead of complete stripping and rebuilding, the method applies partial repair action only to the damaged areas and surrounding zones. This selective approach uses filler material localized to voids and cracks, laminate packs targeted to structural requirements, and overwrap plies confined to the repair area, significantly reducing material and labor costs while restoring integrity.
Solution Approach 2:
The repair methodology changes the approach from traditional extensive reconstruction to a targeted parameter-based repair where the extent of each repair component (filler volume, laminate thickness, overwrap coverage) is determined by the specific damage parameters. This allows cost-effective repairs scaled to actual damage severity.
3Loss of time
If precured laminate packs and overwrap plies are applied to repair damaged rotor blades, then repair time is reduced, but manufacturing complexity increases
Solution Approach 1:
The laminate packs and overwrap plies are precured before application to the rotor blade. This preliminary curing action eliminates the need for complex curing equipment and processes during field repair, reducing repair time and equipment complexity while maintaining structural quality through controlled factory curing conditions.
Solution Approach 2:
The precured laminate packs and overwrap plies function as disposable repair components that are applied and integrated with the blade structure. These pre-fabricated elements simplify the repair process by eliminating the need for complex on-site manufacturing equipment, skilled layup procedures, and extended curing operations, making the repair system more accessible and time-efficient.
Data Source
AI summary
A method of repairing a damaged portion of a rotor blade includes filling the damaged portion with a filler material. A pre-cured patch assembly is applied over the damaged portion, the patch assembly including one or more laminate packs positionable at at least one of an upper rotor blade surface and a lower rotor blade surface and one or more overwrap plies positionable over the upper rotor blade surface and the lower blade surface. A repair structure for a damaged portion of a rotor blade includes a volume of fill material disposed at the damaged portion.