Wind Turbine Blade Root Fastening with Notched Locking Elements
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Solution Overview
Problem
The existing wind turbine blade root region designs face challenges in effectively transferring loads from the fibre composite structure to the hub, leading to potential failure due to insufficient retention of fastening members, especially with longer and heavier blades.
Innovation Solution
The implementation of elongated fastening members with notches and a rod-shaped locking element that securely engages the notch wall, distributing the pulling force over a larger surface area and enhancing retention within the fibre-reinforced composite material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the number of bolts and bushings is increased to handle given loads, then the load transfer capability is improved, but the remaining area of the fibre composite material between the bushings is reduced, resulting in insufficient support for the root connection
Solution Approach 1:
The invention transitions from a two-dimensional retention mechanism (bushings embedded in the surface plane of the composite material) to a three-dimensional mechanism by introducing elongated fastening members that extend through the thickness of the composite material. The locking elements engage the fastening members from both the inner and outer surfaces, creating a through-thickness retention system that distributes loads across the entire depth of the composite structure, thereby maintaining sufficient remaining area in the plane while dramatically improving load transfer capability.
2Weight of moving object
If long and heavy blades are used, then the energy capture capability is improved, but the root connection becomes insufficient to withstand the increased loads
Solution Approach 1:
The invention employs a composite retention system combining metal fastening members (fastening members and locking elements) with the fibre-reinforced composite material of the blade root. The fastening members are embedded in the composite material and extend through its thickness, while the locking elements provide additional mechanical interlocking. This composite approach allows the root connection to withstand the increased loads from long and heavy blades by distributing stresses across both the metal components and the composite material structure.
3Strength
If the root region diameter is increased to accommodate more fastening members, then the load transfer capability is improved, but the overall blade structure becomes more complex and heavier
Solution Approach 1:
The invention applies local quality enhancement by concentrating the retention mechanism at specific locations where fastening members are embedded in the composite material. Rather than uniformly increasing the root region diameter, the elongated fastening members with locking elements provide localized reinforcement at the bolt insertion points. This allows effective load transfer through targeted strengthening at critical locations while maintaining the overall compact dimensions of the root region.
Data Source
AI summary
A wind turbine blade for a wind turbine is a shell structure of a fiber-reinforced composite and comprises a root region and an airfoil region. The root region has a ring-shaped cross section and comprises a plurality of elongated bushings 7 with an inner thread 22 and embedded interspaced in the fiber-reinforced polymer so as to substantially follow the circumference of the root region and allow access from the outside to the inner threads. Each fastening member 7 is provided with a notch 60′ in the periphery 11 thereof. A rod-shaped locking element 61 passes through the notch 60′ in engagement therewith. The locking element 61 is fixedly and tightly fitting arranged in a through-going circular bore 65 extending through the wall of the root region.