Wind Turbine Blade-Hub Joint Repair Using Replacement Bushings
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Solution Overview
Problem
The joints connecting wind turbine rotor blades to the rotor hub experience stress-related issues due to the insufficient shear strength of composite materials, leading to potential failure and costly replacements when adhesive bonds or metal bushings become compromised.
Innovation Solution
A method for repairing the joint by extracting and reconditioning compromised bushings, replacing them with a new insert that includes a bushing and a composite cover, and securing it with an adhesive bond, ensuring a strong interface between the composite material and the new bushing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If threaded stud bolts are directly inserted into composite material at the root end of the rotor blade, then the connection structure is simple, but the composite material has insufficient shear strength to transfer loads between blades and hub
Solution Approach 1:
Metal bushings are introduced as intermediary components between the stud bolts and composite material. The bushings are embedded within axial bores in the composite material and provide a stronger interface for load transfer, while the composite material still serves as the primary structural component. This intermediary solution resolves the contradiction by maintaining structural simplicity while significantly improving shear strength.
2Strength
If metal bushings are embedded in composite material with adhesive bond, then load distribution is improved, but the adhesive bond or blade material at bushing/composite interface may become compromised over time
Solution Approach 1:
The patent implements a repair method that proactively addresses potential interface degradation by providing procedures to inspect, detect, and repair compromised bushings before complete failure occurs. The repair process includes removing compromised bushings, preparing the interface, and installing new bushings with improved adhesive bonding, thereby maintaining long-term reliability and load distribution capability.
3Reliability
If periodic inspections are conducted to detect compromised bushings, then the risk of joint failure is reduced, but the cost of blade replacement remains high when bushings are compromised
Solution Approach 1:
The patent enables extraction and replacement of individual compromised bushings without requiring complete blade replacement. The repair method involves removing only the affected bushing(s), preparing the specific interface area, and installing new bushings, thereby dramatically reducing material loss and replacement costs while maintaining joint integrity through targeted repair of compromised components.
4Power
If the number of wind turbine blades increases with larger blade length, then the energy production capacity is improved, but the joint between blade and rotor hub experiences increased stresses
Solution Approach 1:
The patent utilizes composite materials in the bushing design, combining metal components for strength with composite material integration for load distribution. The bushings are embedded within the composite blade structure, creating a hybrid composite-metal interface that can better withstand the increased stresses associated with larger, more powerful turbine blades while maintaining the energy production benefits of increased blade size.
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 method effectively reestablishes the strength and integrity of the blade-hub joint, reducing the risk of failure and the need for costly blade replacements by providing a secure and durable connection.
Implementation Method 1
securing it with an adhesive bond, ensuring a strong interface between the composite material and the new bushing
Data Source
AI summary
A method of repairing a joint connecting a wind turbine blade to a rotor hub of a wind turbine, wherein the joint includes a plurality of bushings in a root end of the wind turbine blade is disclosed. The method includes extracting a selected bushing from the wind turbine blade, the extraction resulting in a bushing cavity in the wind turbine blade; reconditioning the bushing cavity in the wind turbine blade; providing a replacement insert, wherein the insert includes a replacement bushing and a cover disposed around at least a portion of the replacement bushing; positioning the replacement insert into the reconditioned bushing cavity; and securing the replacement insert to the wind turbine blade.