Modular Wind Turbine Blade Spar Bridge for Tolerance Gaps
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Solution Overview
Problem
Challenges in assembling modular wind turbine blades arise from manufacturing tolerances leading to inconsistent bond gap thickness and alignment issues between spar caps and spar bridges, causing stress concentrations and assembly complications at the wind farm site.
Innovation Solution
A method involving pre-cured layers interleaved with pre-preg interlayers is used to form a spar bridge, where the stack of layers is arranged in a tapered recess with aligned spar caps, and heat is applied to cure the resin, ensuring thorough bonding and alignment, while pre-preg interlayers and fibrous material provide flexibility and electrical conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a separate spar bridge component is used to connect spar caps of adjacent blade modules, then the modular blade can be assembled at the wind farm site, but manufacturing tolerances cause inconsistent bond gap thickness and alignment issues between spar caps and spar bridge
Solution Approach 1:
The spar bridge is segmented into multiple pre-cured layers that can be stacked together. Each layer is manufactured separately with precise dimensions, and when stacked, they collectively fill the bond gap consistently. This segmentation allows each layer to be manufactured with tight tolerances while the stack as a whole accommodates the varying bond gap thickness through the cumulative effect of multiple thin layers.
Solution Approach 2:
The pre-preg interlayers are strategically placed between the pre-cured layers at specific locations where alignment adjustments are needed. These interlayers have different material properties (uncured resin) compared to the pre-cured layers, allowing them to flow and fill gaps locally, providing local quality adjustment to compensate for manufacturing tolerances in the spar cap alignment.
2Ease of operation
If a separate spar bridge component is used to connect spar caps, then modular assembly is enabled, but alignment issues and stress concentrations occur at the connection interface
Solution Approach 1:
The spar bridge is constructed as a composite structure combining pre-cured layers (providing structural strength and stiffness) with pre-preg interlayers (providing gap-filling and stress-distributing properties). This composite material approach creates a more reliable connection by combining materials with complementary properties, where the uncured resin in pre-preg layers flows to fill voids and create uniform stress distribution, reducing stress concentrations at the interface.
Solution Approach 2:
The pre-preg interlayers act as a beforehand cushioning mechanism against potential misalignment and gaps. By incorporating these flexible, gap-filling layers before final curing, the design anticipates and compensates for manufacturing tolerances and alignment variations, preventing stress concentrations before they occur during blade operation.
3Manufacturing precision
If pre-preg interlayers with uncured resin are used in the spar bridge, then flexibility and gap filling are improved, but additional curing time and heat application are required
Solution Approach 1:
The curing process parameters are optimized to balance quality and time. Heat is applied at controlled temperatures and rates to accelerate the curing of pre-preg interlayers without excessive delay. The thickness of pre-preg layers and the heating profile are carefully selected to achieve complete curing in the minimum necessary time while ensuring proper bonding and gap filling.
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
The method ensures consistent load transfer, minimizes stress concentrations, and provides electrical conductivity, reducing assembly time and enhancing the structural integrity of the modular wind turbine blade.
Implementation Method 1
applying heat to the stack of layers in the bridge recess such that the resin in the pre-preg interlayers mobilises in the bridge recess
Implementation Method 2
curing the resin to integrate the pre-cured layers with each other to form a spar bridge spanning the interface
Data Source
AI summary
According to the present invention there is provided a method of assembling a modular wind turbine blade comprising first and second blade modules connectable together at an interface to form at least part of the modular wind turbine blade. The method comprises providing a first blade module and a second blade module. Each blade module comprises an outer shell defining an outer surface of the blade module, a connecting region of the outer shell defining an interface end of the blade module, and a longitudinally-extending spar cap embedded in the outer shell. The spar cap has a tapered end portion in the connecting region in which the thickness of the spar cap decreases towards the interface end of the blade module such that a tapered recess is defined in the outer surface of the blade module. The method further comprises arranging the first and second blade modules end-to-end with the tapered recesses aligned to define a bridge recess. The tapered recess of the first blade module defines a first end of the bridge recess, and the tapered recess of the second blade module defines a second end of the bridge recess. The method further comprises arranging a stack of layers in the bridge recess and spanning the interface between the first and second blade modules. The stack of layers comprises a plurality of pre-cured layers interleaved with pre-preg interlayers. The pre-preg interlayers comprise fibrous material that is pre-impregnated with uncured resin. The method further comprises applying heat to the stack of layers in the bridge recess such that the resin in the pre-preg interlayers mobilises in the bridge recess. The method further comprises curing the resin to integrate the pre-cured layers with each other to form a spar bridge spanning the interface, the spar bridge serving to connect the spar caps of the first and second blade modules.