Composite Blade Root Manufacturing via Chopped Fibre Insert
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Solution Overview
Problem
Conventional methods for manufacturing composite blades, such as fan and propeller blades, face challenges in achieving the required structural strength and smooth shape, particularly at areas with significant cross-sectional changes, leading to potential weaknesses and stress concentrations due to stepped layers and ply drop-off issues.
Innovation Solution
A method involving a chopped fibre composite blade insert is used, which is surrounded by textile composite material and thermoformed in a mould to consolidate the part, eliminating the need for multiple textile layers and allowing for a smooth, accurate shape formation, especially at the root where the cross-sectional area increases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If multiple textile layers are used to form the blade root with significant cross-sectional changes, then the structural strength can be improved, but manufacturing complexity and time increase due to stepped layers and ply drop-off issues
Solution Approach 1:
The blade is divided into two distinct composite material zones: a chopped fibre composite core for the root section and a textile composite outer casing for the airfoil section. This segmentation allows each zone to be optimized independently - the chopped fibre core provides structural strength at the complex root geometry without requiring multiple layered textile plies, while the textile outer casing provides aerodynamic surface quality.
Solution Approach 2:
The invention uses a hybrid composite structure combining chopped fibre composite material and textile composite material. The chopped fibre reinforcement provides bulk structural strength and damage tolerance in the root region, while the textile reinforcement provides surface quality and directional strength in the airfoil region. This composite material approach eliminates the need for complex multi-layer textile construction at the blade root.
2Quantity of substance
If conventional textile layering methods are used at the blade root, then structural coverage can be achieved, but manufacturing time and effort increase significantly
Solution Approach 1:
The chopped fibre blade insert is pre-formed to the exact root geometry including the dorsal fin shape and cross-sectional transitions before being integrated with the textile outer casing. This preliminary formation of the complex root structure eliminates the time-consuming process of building up the root section layer by layer with textile plies during the main blade manufacturing process.
Solution Approach 2:
The blade manufacturing is segmented into independent stages: first forming the chopped fibre insert, then separately forming the textile outer casing, and finally consolidating them together. This segmentation allows parallel processing and eliminates the sequential time penalty of applying multiple textile layers to create the root structure.
3Adaptability or versatility
If stepped layers and ply drop-off are used to accommodate cross-sectional changes, then shape adaptation can be achieved, but weaknesses and stress concentrations are created
Solution Approach 1:
The chopped fibre insert is locally tailored to match the exact cross-sectional geometry of the blade root at each position, including the dorsal fin shape and transitions to the airfoil section. This local geometric matching eliminates the need for stepped layers and ply drop-off, providing continuous stress distribution and avoiding concentration points while adapting to the complex root shape.
Solution Approach 2:
The blade insert incorporates smooth curved transitions and continuous dorsal fin shaping rather than angular stepped changes. This curvature approach to geometry adaptation ensures continuous stress flow paths through the composite structure, eliminating the stress concentrations that would arise from abrupt ply drop-offs and angular transitions.
4Shape
If a smooth accurate shape is formed at the blade root, then aerodynamic quality can be improved, but conventional textile layering creates stepped layers that compromise the shape
Solution Approach 1:
The chopped fibre composite material is used specifically for the blade root section where complex three-dimensional shaping is required. This material type naturally forms smooth continuous surfaces without the stepped layer structure inherent in textile laminates, providing inherent surface quality for the root geometry while the textile outer casing provides the aerodynamic surface for the airfoil section.
Solution Approach 2:
The blade is segmented such that the chopped fibre insert handles the complex root shaping requirements while the textile outer casing handles the aerodynamic airfoil surface requirements. This segmentation assigns the smooth complex root shape formation to the chopped fibre section, eliminating the need for complex textile layering to achieve root surface quality.
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 reduces manufacturing time and effort while providing structural properties comparable to conventional techniques, minimizing weaknesses and stress concentrations, and enabling the formation of complex shapes with improved load-bearing capabilities.
Implementation Method 1
thermoforming the blade insert and the surrounding textile composite material in a thermoforming mould in order to consolidate the part
Data Source
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AI summary
A method is disclosed for manufacture of a composite blade 12 with an airfoil 14 and a root 16, wherein the blade 12 comprises a core 18 of chopped fibre composite material and a textile composite material 20 encasing the chopped fibre core 18. The method comprises: forming a blade insert 18 using chopped fibre composite; surrounding the blade insert 18 with a plurality of layers of a textile in a textile composite material 20; and thermoforming the blade insert 18 and the surrounding textile composite material 20 in a thermoforming mould in order to consolidate the part.