Wind Turbine Blade Root Repair With Hybrid Adapter Reinforcement
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Solution Overview
Problem
Existing methods for repairing the connection between the root of a wind turbine blade and its bushing fail to effectively address the issue of delamination and crack propagation due to stress and fatigue, leading to potential catastrophic failure.
Innovation Solution
A repair method that alternates glued insert technology with T-bolt technology, involving cutting, cleaning, laminating, and installing an adapter in situ, using prefabricated composite material sectors and an adapter to reinforce the non-aerodynamic area of the blade root.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing repair methods (reinforcing fiber, resin curing, bushing extraction, cup replacement) are used, then local damage is addressed, but delamination and crack propagation due to stress and fatigue are not effectively prevented
Solution Approach 1:
The repair method divides the connection interface into three distinct zones: a first zone with original blind axial holes and threaded cups, a second zone with new blind axial holes and threaded cups, and a third zone with T-bolts. This segmentation allows each zone to address specific repair needs while collectively preventing delamination and crack propagation through distributed reinforcement.
Solution Approach 2:
The adapter is inserted into the hollow interior of the bushing, creating a nested structure where the adapter (with its bearing) is housed within the bushing cavity. This nested arrangement provides additional structural support and reinforcement without increasing the external dimensions, effectively preventing crack propagation while maintaining connection reliability.
2Reliability
If the bushing or its connection to the root fails, then delamination occurs and cracks propagate, but catastrophic failure can be prevented by implementing a multi-zone reinforcement structure
Solution Approach 1:
The adapter is prepared in advance with the bearing installed and positioned within the bushing cavity before final assembly. The T-bolts are pre-positioned in the third zone, and the blind axial holes are pre-drilled and threaded in both the first and second zones. This preliminary preparation ensures that when the bushing or connection fails, the multi-zone reinforcement structure is already in place to prevent catastrophic failure.
3Strength
If glued insert technology is used alone, then inserts are secured, but the alternation with T-bolt technology provides enhanced structural reinforcement
Solution Approach 1:
The repair method merges two different joining technologies: glued inserts (threaded cups in the first zone) and T-bolt technology (third zone). The threaded cups are secured with adhesive material, while the T-bolts provide mechanical reinforcement. This combination of bonding and mechanical fastening creates a hybrid connection system that leverages the advantages of both methods to achieve superior connection strength.
Solution Approach 2:
The solution uses composite material construction by combining different joining mechanisms (adhesive-bonded threaded cups and mechanically-fastened T-bolts) within the same repair structure. This composite approach to joining technology creates a multi-modal reinforcement system that addresses both chemical bonding and mechanical interlocking, significantly enhancing overall connection strength.
Data Source
Figure 1~2
Figure 3~4A
Figure 4b~4c
AI summary
Method for repairing a root of a blade having the following sequence: loosening the bolts (6) of the root of the blade (5) by removing the nuts (20) in the bearing (7) of the bushing (3). Lowering the blade to the ground using the Bladerunner®. Cutting a diametral ring of the blade that includes the surface (10) where the threaded cup (9) housing the nut (6) is included. Cleaning up and laminating the bevelled area (11). Machining a long bore passing through the bevelled area (13) and a short and through bore (14) in the thickness direction. Adding and adapter (15) that combines both technologies (one per each end) and allows the length of the blade (4) to be increased and consequently its AEP (Annual Energy Production) is increased. Said adapter (15) is a ring with through holes (17 and 22) over its entire surface, which is attached on the portion of the root of the blade (5) with T-bols and on the portion of the bushing (3) with the bolts (6) that have been previously removed, housed in the inserts (9).