Composite Fan Blade Design via Segmented Mold and Core
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Solution Overview
Problem
The existing design process for composite airfoils in gas turbine engine fan blades is inefficient, requiring time-consuming redesigns whenever changes are made, as the mold, core, and plies must be re-designed in sequence, leading to increased complexity and time in adapting to design modifications.
Innovation Solution
The method involves designing the mold first, followed by the woven core, and then the plies, allowing for staggered and spread-out ply drops to prevent crack and delamination propagation, with an automated tool to populate the voids between the mold and core with plies, reducing the need for sequential redesigns and enabling faster iterative changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the mold, core, and plies are designed in sequential order with strict dependencies, then the structural integrity and aerodynamic profile are ensured, but any design change requires complete redesign of all subsequent components, significantly increasing redesign time and complexity
Solution Approach 1:
The design process is segmented into independent modules: mold design, core design, and ply design. Each module can be designed and modified independently without requiring complete redesign of subsequent modules. The core is designed as a separate entity that fits within the mold cavity, and plies are designed to conform to both the mold and core surfaces, creating independent design spaces that reduce interdependence.
Solution Approach 2:
The mold is designed first to establish the airfoil profile, and the core is pre-designed to fit within the mold cavity. These preliminary designs create a framework that allows subsequent ply designs to be made independently. The preliminary actions of mold and core design establish boundaries and constraints that guide but do not rigidly determine the ply design, enabling faster iterations.
2Loss of substance
If ply drops are concentrated in specific areas to optimize structural efficiency, then material usage is reduced, but stress concentration increases, leading to higher risk of crack and delamination propagation
Solution Approach 1:
The ply configuration is optimized locally at each position along the blade span. Ply drops are distributed and staggered rather than concentrated, creating varying local qualities in the laminate structure. This local optimization ensures that each region has the appropriate ply orientation and thickness for its specific stress conditions while avoiding stress concentration that would occur with concentrated ply drops.
Solution Approach 2:
Instead of avoiding ply drops entirely (which would require more material), the design accepts their inevitability and converts the potential harm of stress concentration into a benefit by strategically distributing and staggering them. The ply drops are positioned and oriented to transform stress concentration points into stress distribution patterns that enhance overall structural reliability while maintaining material efficiency.
Data Source
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AI summary
A method for designing a composite airfoil (10), comprises designing a mold (32) having an inner surface (32i) that defines a surface profile of the airfoil, defining a preliminary core surface of a woven core (30), wherein the preliminary core surface is offset from the inner surface of the mold (32i) by a specified percentage, filling the space between the mold (32) and the preliminary core surface with a plurality of plies (26) and assembling the woven core (30) and the plurality of plies (26) in the mold (32) and curing to form the composite airfoil (10).