Pre-polymerized Composite Parts with Peel Ply Gradient
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Solution Overview
Problem
Existing methods for producing and bonding composite material parts in the aeronautical field face issues such as unreliable bonded joints, complex equipment handling, high costs, and the need for surface preparation and nondestructive testing, particularly in co-curing and secondary-bonding methods.
Innovation Solution
A pre-polymerized fiber-reinforced composite material part with a polymerization gradient at the interface between the structure and a peel ply, allowing for co-curing bonding while reducing costs and simplifying manufacturing and testing processes, achieved by modifying the fibrous fabric to be lightly laden with curing agent, creating an under-polymerized zone at the bonding interface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If co-curing bonding method is used to assemble parts, then mechanical strength of bonded joint is improved, but device complexity and handling difficulty increase
Solution Approach 1:
The patent applies preliminary action by pre-polymerizing the resin in the composite parts before assembly, creating a partially cured state with optimized bonding characteristics. The resin is polymerized to a specific degree (e.g., 30-70% conversion) in advance, which prepares the bonding interface for subsequent assembly while avoiding the need for complex real-time curing equipment during assembly operations.
Solution Approach 2:
The patent changes the polymerization degree parameter of the resin from fully cured (0% or 100%) to a partial polymerization state (30-70% conversion). This parameter change allows the resin to exhibit optimal properties for both handling during assembly and bonding strength, resolving the contradiction between ease of handling and joint strength.
2Ease of manufacture
If secondary-bonding method is used to assemble parts, then ease of manufacture and handling is improved, but reliability of bonded joint deteriorates
Solution Approach 1:
The patent changes the polymerization degree parameter to a partial cured state (30-70% conversion), which provides optimal balance between handling ease and bonding reliability. The partially polymerized resin maintains sufficient viscosity for easy handling and storage while retaining reactive groups for reliable bonding during assembly.
Solution Approach 2:
The patent uses an adhesive film as a disposable intermediate element that facilitates reliable bonding. The adhesive film is positioned between parts during assembly and is subsequently removed or integrated, providing a simple and reliable bonding solution without requiring complex equipment or procedures.
3Ease of manufacture
If co-bonding method is used to assemble parts, then ease of manufacture is improved, but reliability of bonded joint deteriorates due to kissing bonds
Solution Approach 1:
The patent changes the polymerization degree to a partial cured state (30-70% conversion) before assembly, which prevents kissing bonds by ensuring the resin remains sufficiently reactive and mobile during bonding. This parameter change allows complete infiltration and bonding without the resin becoming too rigid or viscous, thereby maintaining joint reliability.
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 solution enables the production of parts with reliable bonded joints and reduced manufacturing complexity, eliminating the need for surface preparation and simplifying storage and handling, while maintaining mechanical strength similar to co-curing bonding methods.
Implementation Method 1
curing the resin, by polymerization, under a vacuum cover, in an autoclave or an oven
Implementation Method 2
diffusing thermosetting resin uniformly, by injection or infusion, into the fibrous preform
Data Source
AI summary
A part made of a fiber-reinforced composite material includes a structure made from a set of fibers supported in a thermosetting resin and a peel ply across all or part of the outer surface of the structure. The part has a gradient of polymerization at the interface between the structure and the peel ply. Also, methods for making such a part and methods for bonding such parts.