Composite Part Hollow Cavity Design for Stiffness and Mass
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Solution Overview
Problem
Existing methods for producing composite material parts for aeronautical turbomachines face challenges such as delamination, poor adhesion between layers, and damage to low-density foams during insertion, which affect the part's stiffness and mass savings.
Innovation Solution
A method involving the production of a fibrous preform and a rigid core, where the rigid core is inserted into the preform and a matrix is injected to impregnate the preform, followed by a heat-treatment step to polymerize the matrix, resulting in a composite part with enhanced stiffness and reduced mass.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a low-density foam core is inserted into a fibrous preform, then mass savings are achieved, but the foam risks being damaged during insertion and may break or crumble
Solution Approach 1:
The patent extracts the foam core from the composite structure entirely, replacing it with a hollow cavity formed directly in the mould. This eliminates the foam insertion step that causes damage while maintaining the mass savings benefit through the hollow design.
Solution Approach 2:
The patent uses a disposable mould insert or sacrificial material that is removed after a single use, eliminating the need for durable foam cores that require careful handling and insertion. The mould insert is discarded after forming the hollow cavity, simplifying the process.
2Strength
If a honeycomb structure is used as core, then bending stiffness is increased, but resin fills the cells and reduces mass saving
Solution Approach 1:
The patent extracts the honeycomb structure entirely, replacing it with a simple hollow cavity. The hollow cavity provides sufficient bending stiffness for many applications without the complexity of honeycomb cells, and crucially, resin cannot fill the cavity to add unwanted weight.
Solution Approach 2:
The patent applies local quality by creating a hollow cavity only where mass savings are needed, while maintaining solid composite structure in areas requiring high strength. This selective approach optimizes the balance between stiffness and weight.
3Manufacturing precision
If precise dimensions are imposed on foam core, then geometrical requirements are met, but foam becomes weak and more prone to breaking
Solution Approach 1:
The patent removes the foam core entirely and forms the hollow cavity directly in the mould, eliminating the insertion step where dimensional precision and foam strength conflict. The cavity dimensions are controlled by the mould itself, ensuring precision without compromising any core material strength.
4Reliability
If three-dimensional weave is used, then delamination resistance is improved, but production complexity increases
Solution Approach 1:
The patent extracts the complex three-dimensional weave requirement by using a simpler two-dimensional weave combined with a hollow cavity. The hollow cavity itself provides delamination resistance by acting as a barrier, eliminating the need for complex 3D woven preforms.
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
The method achieves a composite part that is both lighter and more rigid, capable of resisting various stresses during production and use, while maintaining the desired aerodynamic profile and mechanical properties.
Implementation Method 1
a heat-treatment step, during which polymerisation of the matrix is carried out
Data Source
AI summary
A method for producing a part, in particular a part made of composite material, in particular for a turbomachine, including at least: a step of producing a preform, during which a fibrous preform intended to form an outer skin of the part is produced; a step of producing a core, during which a rigid core, in particular a hollow rigid core, intended to form a framework of the part is produced; an insertion step, during which the rigid core is inserted into the fibrous preform, an injection step, during which a matrix is injected into the fibrous preform; and a heat-treatment step, during which polymerisation of the matrix is carried out.