Rotor Blade Stiffening Root Insert Design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Larger rotor blades in wind turbines experience increased stress and fatigue at the blade root joint due to high stress concentrations, manufacturing defects, and unexpected loading events, leading to potential structural failure and reduced fatigue life.
Innovation Solution
A rotor blade assembly with a rigid root insert configured in a T-bolt connection, where the insert is compressed by bolts and cross-bolt components to increase stiffness and reduce loads on the joint, using a radial and longitudinal bore hole configuration and internal threading for enhanced preload.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If rotor blade size is increased to enhance energy production capacity, then energy production increases, but stress and fatigue at the blade root joint increase leading to reduced reliability
Solution Approach 1:
The blade root assembly uses a composite structure combining a blade root laminate (composite material) with a rigid root insert (metal or dense composite material). This composite construction allows the blade root to achieve both the flexibility needed for energy capture and the rigidity needed to resist stress concentrations, thereby maintaining reliability while supporting larger blade sizes for increased energy production.
Solution Approach 2:
The rigid root insert is strategically positioned within the blade root laminate at the critical junction where stress concentrations occur. This localized reinforcement provides enhanced strength and stiffness precisely where needed to withstand the increased loads from larger blades, without requiring the entire blade root structure to be oversized.
2Productivity
If larger rotor blades are used to increase span and energy capture, then energy production increases, but stress concentration at the blade root connection increases
Solution Approach 1:
The combination of blade root laminate and rigid root insert creates a composite structure that distributes stress more evenly across the blade root connection. The rigid insert acts as a stress-dispersing element that prevents stress concentration at the interface between the blade root and hub, enabling larger blades to operate without excessive stress at the connection point.
Solution Approach 2:
The rigid root insert serves as an intermediary element between the blade root laminate and the hub connection. It mediates the stress transmission by providing a rigid transition zone that reduces stress concentrations at the interface, allowing larger blades to be connected to the hub without excessive stress at the connection point.
3Ease of manufacture
If conventional blade root connections are used, then manufacturing is simpler, but fatigue life is reduced due to high stress and potential structural failure
Solution Approach 1:
The blade root laminate combined with the rigid root insert creates a composite structure that significantly improves fatigue life. The rigid insert provides a stress-distributing framework that prevents crack propagation and reduces the impact of stress concentrations, thereby extending the fatigue life of the blade root connection while remaining manufacturable through standardized composite construction processes.
Solution Approach 2:
The rigid root insert is integrated into the blade root laminate at specific locations where fatigue resistance is most critical. This localized reinforcement targets the areas most susceptible to fatigue failure, extending the overall fatigue life of the blade root connection without requiring complete redesign of the entire blade root structure, thus maintaining ease of manufacture.
Data Source
AI summary
A rotor blade assembly for a wind turbine having a rigid root insert is disclosed. The rotor blade assembly includes a blade root section having an end face with a substantially annular cross-section defined by an outer sidewall surface and an inner sidewall surface. The end face is configured to attach the rotor blade assembly to a hub. The rotor blade assembly includes a radial bore hole provided a predetermined span-wise distance from the end face and extending between the sidewall surfaces and a longitudinal bore hole provided between the sidewall surfaces and extending from the end face to the radial bore hole. The rigid root insert is disposed within the longitudinal bore hole and extends from the end face to the radial bore hole. As such, the rigid root insert is configured to increase the stiffness of the blade root section when the rotor blade assembly is attached to the hub with bolts that extend into and through the radial bore hole and the longitudinal bore hole.