Unidirectional Reinforcement with Transverse Flow Passages
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Solution Overview
Problem
Current unidirectional reinforcement methods face challenges with transverse stability, resin permeability, and fatigue properties, particularly in lengthy composite structures like wind turbine blades, due to issues such as kinking, stress concentrations, and inefficient resin impregnation, which affect the strength and production efficiency of laminates.
Innovation Solution
The use of thin discrete flow passages formed by monofilaments or multifilaments arranged transversely to the unidirectional rovings, which facilitate resin flow and air escape during vacuum infusion, replacing stitching and transverse yarns to enhance permeability and maintain fiber straightness, while a thermoplastic or thermoset binder provides transverse stability without compromising strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If stitching is used to hold rovings together, then transverse stability is improved, but resin permeability deteriorates and kinking occurs
Solution Approach 1:
The patent removes the stitching element from the reinforcement structure and replaces it with a thermoplastic binder that bonds rovings together. This extraction eliminates the harmful effects of stitching (kinking, poor resin permeability) while maintaining transverse stability through the binder system.
Solution Approach 2:
The patent replaces the mechanical stitching system with a chemical bonding system using thermoplastic or thermoset binders. This substitution eliminates the physical penetration and kinking caused by needles while providing adequate transverse stability through adhesive bonding.
2Ease of operation
If transverse yarns are used to provide stability, then handling properties are improved, but fatigue properties deteriorate due to stress concentrations
Solution Approach 1:
The patent removes transverse yarns from the reinforcement structure and replaces them with a binder system. This extraction eliminates the stress concentration points created by transverse yarn intersections while maintaining handling stability through the bonded roving structure.
3Stability of the object's composition
If conventional unidirectional reinforcement is used, then fiber orientation is maintained, but resin impregnation speed deteriorates
Solution Approach 1:
The patent creates a porous structure by spacing rovings apart using spacers, which opens channels for resin flow. This porous arrangement maintains fiber orientation while dramatically improving resin impregnation speed through the created flow pathways.
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 improves resin flow and impregnation speed, reduces void formation, and enhances the fatigue and strength properties of laminates, allowing for more efficient production of complex composite structures with improved handling and reduced risk of micro-cracking.
Implementation Method 1
bonded to each other by a thermoplastic and/or thermoset binder
Implementation Method 2
bonded to each other by a thermoplastic and/or thermoset binder
Implementation Method 3
when wetting-out a stack of reinforcements, the impregnation of the reinforcement with resin in a direction transverse to the direction of the unidirectional rovings
Implementation Method 4
allow air to escape from a stack of reinforcements during vacuuming/degassing
Data Source
AI summary
A method to produce a unidirectional reinforcement for fiber reinforced composites by a resin transfer or vacuum infusion molding process include: laying continuous rovings unidirectionally side by side in one layer for forming a unidirectional web, applying thermoplastic or thermoset binder on the web, activating the binder for bonding the rovings together to form a unidirectional reinforcement, and forming flow passages for resin in a direction transverse to the direction of the unidirectional rovings by laying thin discrete flow passage having, under compression, an aspect ratio of equal or less than 2 on the continuous unidirectional rovings.