CFRP Metalwork Debonding with Controlled Cleaving and Local Heating
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Solution Overview
Problem
Current methods for debonding metalwork from carbon fibre reinforced polymer (CFRP) in aircraft fan blades often require corrosive chemicals or risk overheating the polymeric components, making them inefficient and damaging.
Innovation Solution
A method and tool that use a cleaving tool with a controlled force system, accompanied by a heating component to soften the adhesive, allowing for precise debonding by matching the calculated de-bonding force and temperature to avoid damage to the CFRP.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If heating is used to soften the adhesive and cause the metal to expand, then the metalwork can be removed from the polymeric component, but there is a risk of overheating and damaging the polymeric component
Solution Approach 1:
The heating element is positioned to apply heat locally only to the metalwork and adhesive interface, not to the entire assembly. This localized heating softens the adhesive and expands the metal at the bonding interface while keeping the polymeric component temperature within safe limits, resolving the contradiction between ease of removal and prevention of overheating damage
Solution Approach 2:
The metalwork acts as an intermediary that absorbs and concentrates the heat from the heating element, preventing direct heat transfer to the polymeric component. The metal expands and softens the adhesive through controlled heating, enabling removal while protecting the polymer from excessive temperature exposure
2Ease of manufacture
If a corrosive chemical etchant is used to remove the metal, then the metalwork can be removed from the polymeric component, but the polymeric component may be damaged by the corrosive chemical
Solution Approach 1:
The chemical etching process is replaced with a thermal-mechanical process. Instead of using corrosive chemicals to dissolve or etch away the metal, a heating element softens the adhesive and the metalwork is mechanically removed through controlled expansion and separation, eliminating chemical exposure risks to the polymeric component while maintaining ease of removal
Solution Approach 2:
The removal process transitions from chemical parameter changes (corrosive etching) to thermal parameter changes (controlled heating). By changing the adhesive's physical state through heating rather than chemical degradation, the metalwork can be removed without exposing the polymeric component to harmful chemicals
3Ease of operation
If manual peeling is used for trailing edge metalwork, then the removal process is simple, but the leading edge metalwork with greater thickness and bonded width requires significantly higher peel force making manual removal harder or impossible
Solution Approach 1:
The heating element serves as an intermediary that reduces the bond strength between metalwork and polymeric component by softening the adhesive. This mediation allows thick leading edge metalwork with large bonded width to be removed with manageable force, combining the simplicity of a straightforward process with reduced force requirements
Solution Approach 2:
The physical state of the adhesive is changed through heating, transitioning from a rigid bonded state to a softened, more compliant state. This parameter change reduces the peel force required for removal, enabling even thick leading edge metalwork to be removed easily while maintaining process simplicity
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 effectively debonds metalwork from CFRP without using corrosive chemicals, reducing the risk of overheating and minimizing damage to the polymeric components, enabling efficient and safe removal of metalwork from fan blades.
Implementation Method 1
a heating component arranged to heat a portion of the adhesive forward of the blade to a set temperature to soften the adhesive
Implementation Method 2
exerting a controlled force on the cleaving tool to move the cleaving tool so as to de-bond the first and second layers in a region
Data Source
AI summary
A method of debonding a first layer from a second layer, wherein the first layer is bonded to the second layer by an adhesive located between the first and second layers. The method includes inserting a blade of a cleaving tool between the first and second layers, and exerting a controlled force on the cleaving tool to move the cleaving tool so as to de-bond the first and second layers in a region. The force exerted is controlled to match a de-bonding force calculated for the region, and such that the movement of the cleaving tool stops when the calculated force is less than a force required to move the cleaving tool, and continues when the calculated force is higher than or equal to the force required to move the cleaving tool.