Fibre Preform with Stiffening Strip for Curved Moulds
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Solution Overview
Problem
The existing methods for manufacturing wind turbine blades are complex and time-consuming, particularly in reinforcing the root section, which requires high flexural strength, and involve risks such as stress concentration from bends or creases in fibre-reinforced plastic (FRP) sheets, necessitating a faster and safer method for laying FRP sheets into a mould.
Innovation Solution
A fibre preform method involving a stack of dry reinforcing material plies with a stiffening strip, oriented in the chordwise direction, that is self-supporting on a curved mould surface, allowing for quicker assembly and reducing the risk of slumping, and can be infused with resin and cured without specialized handling or anchoring to the mould.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the number of layers of FRP is increased to reinforce the blade structure, then the flexural strength is improved, but the manufacturing time increases
Solution Approach 1:
Multiple separate FRP sheets are merged into a single preformed stack, allowing them to be placed into the mould as one unit. This combining of multiple placement operations into a single operation reduces manufacturing time while maintaining the required number of layers for flexural strength.
Solution Approach 2:
The FRP sheets are pre-assembled into a stacked configuration before being placed into the mould. This preliminary action of stacking the sheets in the correct sequence and orientation beforehand eliminates the time-consuming process of individually placing each sheet during mould assembly.
2Manufacturing precision
If individual FRP sheets are carefully laid into the mould, then the quality is improved, but the productivity decreases
Solution Approach 1:
Multiple FRP sheets are combined into a preformed stack that maintains the quality requirements through pre-assembly. The stack is constructed with proper alignment and bonding of sheets before mould placement, ensuring quality is not compromised while enabling faster production.
Solution Approach 2:
The quality-critical assembly operations are performed in advance during preform manufacturing, allowing for careful construction of the FRP stack under controlled conditions. This preliminary quality assurance enables faster mould placement without sacrificing manufacturing precision.
3Productivity
If FRP sheets are laid quickly into the mould, then the productivity is improved, but the risk of formation defects increases
Solution Approach 1:
The FRP sheets are pre-assembled into a stable stacked configuration with proper bonding and alignment before mould placement. This preliminary structuring ensures that when the stack is quickly placed into the mould, the sheets remain in their correct positions and orientations, preventing formation defects while maintaining high productivity.
4Loss of time
If multiple FRP sheets are stacked and bound together, then the assembly time is reduced, but the device complexity increases
Solution Approach 1:
The FRP reinforcement is segmented into discrete preformed stacks that can be independently manufactured and then quickly placed into the mould. This segmentation into modular units reduces assembly complexity during mould fabrication, as each stack is a self-contained component that simplifies the overall assembly process.
Data Source
AI summary
A method for making a root section (7) of a wind turbine blade (5), the method comprising: providing a fiber preform (14) comprising the steps of: providing at least one first ply of dry reinforcing material (15); placing a stiffening strip (25) on the at least one first ply of dry reinforcing material; placing at least one second ply of dry reinforcing material on the stiffening strip to form a stack; and binding the stack together along binding rows (16); the method further comprising placing the fiber preform on a curved mold surface such that the binding rows and the stiffening strip are orientated in a chordwise direction; wherein the stiffening strip has a stiffness such that the stack is self-supporting so that the stack does not buckle when laid on the curved mold surface.