Composite Laminate Interlayer Thickness Reduction via Soluble Thermoplastic Dissolution
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Solution Overview
Problem
The existing methods for composite laminates often result in substantial thickness increases due to interlayers used to impede crack propagation, which is undesirable.
Innovation Solution
A method of fabricating a composite laminate by forming a stack with first and second fiber beds and an interlayer, where the interlayer includes an insoluble component and a soluble thermoplastic component, and dissolving the soluble thermoplastic component into the matrix resin to reduce the interlayer thickness to between 2 and 8 microns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If interlayers are used to impede crack propagation, then crack propagation resistance is improved, but laminate thickness increases substantially
Solution Approach 1:
The patent applies parameter changes by transforming the interlayer from a thick, non-dissolving structure to a thin, dissolving structure. The interlayer thickness is reduced to 2-20 microns and made soluble in the matrix resin, allowing it to dissolve completely during curing. This parameter transformation maintains crack propagation resistance through the insoluble component while eliminating thickness increase through complete dissolution of the soluble thermoplastic component.
Solution Approach 2:
The patent utilizes phase transitions by employing a thermoplastic component that transitions from a solid interlayer structure to a dissolved state in the matrix resin. The soluble thermoplastic component dissolves during the curing process, transitioning from a distinct phase (interlayer) to being integrated into the matrix resin phase, thereby eliminating the interlayer thickness while maintaining its crack impeding function through the insoluble component.
2Length of stationary object
If interlayer thickness is reduced, then laminate thickness is decreased, but crack propagation resistance may be compromised
Solution Approach 1:
The patent applies composite materials by creating a dual-component interlayer structure combining soluble thermoplastic and insoluble components. The insoluble component (such as inorganic particles, fibers, or crosslinked polymer) provides the essential crack propagation resistance, while the soluble thermoplastic component provides processing benefits and complete dissolution. This composite structure enables thin interlayer thickness (2-20 microns) while maintaining adequate toughness through the insoluble component.
Solution Approach 2:
The patent applies the extraction principle by separating the crack propagation resistance function from the thickness-providing function. The insoluble component retains the crack impeding capability, while the soluble thermoplastic component is extracted/dissolved during curing to eliminate excess thickness. This functional separation allows the interlayer to provide crack resistance without contributing to final laminate thickness.
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 effectively reduces the interlayer thickness while maintaining crack propagation resistance, allowing for a thinner composite laminate without compromising toughness.
Implementation Method 1
dissolving entirely or partially the soluble thermoplastic component into the matrix resin to reduce thickness of the interlayer
Data Source
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AI summary
A method of fabricating a composite laminate comprises forming a stack including first and second fiber beds and an interlayer between the fiber beds. The fiber beds are impregnated with matrix resin. The interlayer includes a soluble thermoplastic component on an insoluble component. The method further comprises dissolving the soluble thermoplastic component into the matrix resin to reduce thickness of the interlayer.