Spar Cap Joining via Resistive Heating of Weldable Resin
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The production of spar caps for wind turbine blades faces challenges such as misalignment, material shifting, and infusion defects during the manufacturing process, leading to defects and high costs in repair and material inefficiencies.
Innovation Solution
A method involving the use of structural elements with weldable resin, where layers are arranged side by side and joined using a resistive element that softens or melts the resin upon energization, minimizing material between layers and enhancing structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If planks are packed directly in the mold to form the spar cap during infusion, then the spar cap can be formed as part of the blade structure, but misalignment and shifting of adjacent materials occur leading to infusion defects
Solution Approach 1:
The spar cap planks are pre-aligned and secured to the blade mold before the infusion process begins. This preliminary positioning ensures that the planks remain in correct alignment throughout the subsequent resin injection, eliminating misalignment and shifting defects while maintaining integration of spar cap formation with blade manufacturing.
2Manufacturing precision
If a separate infusion process is used to form the spar cap as a prefabricated part, then alignment issues are avoided, but additional non-structural material is added reducing mechanical performance
Solution Approach 1:
The invention merges the spar cap formation process with the blade manufacturing process by integrating the plank placement and resin infusion into a single operation. This eliminates the need for separate prefabrication steps and the associated non-structural interplank materials, while maintaining precise alignment through pre-positioning fixtures and secured mounting on the mold surfaces.
3Reliability
If additional fabric layers are added between planks to guarantee resin flow, then complete wetting is achieved, but non-functional weight is added to the final blade
Solution Approach 1:
The invention employs the natural porosity and surface characteristics of the pultruded plank materials themselves to facilitate resin flow and complete wetting. By properly preparing the plank surfaces and positioning them with appropriate gaps, the resin can flow through and wet the plank interfaces without requiring additional fabric layers, thereby eliminating non-functional weight while maintaining reliable resin impregnation.
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 allows for efficient production of spar caps with minimal non-structural material, reducing costs and improving mechanical performance while facilitating easier inspection and repair.
Implementation Method 1
energizing the resistive element such that the weldable resin softens or melts
Implementation Method 2
energizing the resistive element such that the weldable resin softens or melts (thereby joining the first and the second layer of structural elements)
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A method of producing a spar cap or a part thereof comprises providing a plurality of structural elements (30) each comprising fibres and a weldable resin; arranging at least two of the structural elements (30) side by side, thereby forming a first layer (40); arranging at least two further structural elements (30) side by side, thereby forming a second layer (42); placing a resistive element (50) between the first and second layers (40, 42); and while pressing the first and second layers (40, 42) together, energising the resistive element (50) such that the weldable resin softens or melts, thereby joining the first and second layers (40, 42) of structural elements (30). The structural elements (30) may be pultrusion planks. Also disclosed is a spar cap obtainable by this method as well as a wind turbine blade comprising such spar cap.