Stitched Unidirectional Reinforcement with Transverse Flow Passages
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing stitched unidirectional or multi-axial reinforcements face challenges with limited resin permeability and the presence of gas bubbles or dry regions, which hinder the production of high-quality, high-strength composite products, especially in lengthy structures like wind turbine blades.
Innovation Solution
The use of thin discrete flow passage forming means, such as monofilaments or bundles of monofilaments, arranged transversely to the reinforcing rovings to create efficient flow passages for resin and air removal, facilitating better resin impregnation and degassing during the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional stitched unidirectional or multi-axial reinforcements are used, then the reinforcement structure provides mechanical strength and stability, but the resin permeability is limited and gas bubbles or dry regions remain in the product
Solution Approach 1:
The patent introduces a porous foam layer between the reinforcement layers, creating a controlled porous structure that facilitates resin flow and gas evacuation. The foam layer acts as a reservoir and transport medium, allowing resin to penetrate efficiently and gas bubbles to escape, thereby eliminating dry regions and improving product quality without compromising the mechanical integrity of the reinforcement structure.
Solution Approach 2:
The foam layer serves as an intermediary substance between the reinforcement layers and the resin. It mediates the interaction by providing a pathway for resin flow and a collection system for gas bubbles, enabling efficient impregnation and degassing processes that would be difficult to achieve with traditional reinforcement structures alone.
2Strength
If reinforcement layers are placed closely together to maintain structural integrity, then mechanical strength is improved, but resin flow and air removal become difficult
Solution Approach 1:
The foam layer introduces a controlled porous structure between closely spaced reinforcement layers. This porous medium provides dedicated flow channels for resin penetration and gas evacuation, enabling efficient impregnation even when reinforcement layers are placed closely together to maintain structural integrity and mechanical strength.
Solution Approach 2:
The foam layer adds a third dimension (Z-direction) to the reinforcement structure, creating vertical flow pathways that complement the in-plane resin flow. This dimensional addition provides escape routes for gas bubbles and enhances resin penetration efficiency without requiring increased spacing between reinforcement layers, thus maintaining mechanical strength while improving productivity.
3Stability of the object's composition
If stitching density is increased to improve handling stability, then reinforcement stability is improved, but resin permeability and gas removal are hindered
Solution Approach 1:
The foam layer compensates for the reduced stitching density by providing an alternative mechanism for reinforcement stability through its cellular structure. The porous foam maintains spacing and structural integrity while simultaneously facilitating resin flow and gas removal, allowing stitching to be optimized for handling stability without compromising permeability.
Solution Approach 2:
The foam layer acts as an intermediary that decouples the functions of stability and permeability. It provides structural support and spacing maintenance that would otherwise require dense stitching, while its porous structure independently handles resin flow and gas evacuation, allowing optimization of stitching density for handling stability without hindered resin permeability.
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 approach significantly enhances resin flow and air removal, increasing the wet-out distance and reducing impregnation time, resulting in stronger and fatigue-resistant composite products with minimal dry areas or voids.
Implementation Method 1
thin discrete means for forming flow passages for resin arranged transverse to the unidirectional or multi-axial rovings, the thin discrete flow passage forming means forming to the sides thereof flow passages extending from one edge of the stitched unidirectional or multi-axial reinforcement to the opposite edge
Implementation Method 2
facilitating the flow of resin in a direction transverse to the direction of the unidirectional rovings, wherein the impregnation facilitating means are thin discrete means for forming flow passages for resin
Implementation Method 3
excellent capabilities to allow air to escape from a stack of reinforcements during vacuuming/degassing and subsequent wetting-out the stack with resin
Data Source
AI summary
A stitched unidirectional or multi-axial reinforcement and a method of producing a stitched unidirectional or multi-axial reinforcement includes transversely arranging thin discrete flow passage forming means having a diameter of 70-300 μm in a direction transverse to the direction of the unidirectional rovings at least on the continuous rovings of the at least one layer, and stitching the thin discrete flow passage forming means and the continuous unidirectional rovings to one another to form a reinforcement.