Reprocessing Fiber-Composite Parts via Thermal Realignment
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Solution Overview
Problem
Current methods for reprocessing fiber-composite parts, such as carbon fiber reinforced polymers (CFRPs), either shorten fibers significantly or fail to recover 100% of the original fibers, leading to inferior performance in reprocessed parts due to randomized fiber orientation or energy-intensive polymer removal processes.
Innovation Solution
A method that realigns fibers in previously molded parts into unidirectional preforms by heating the parts above the glass transition temperature and applying force vectors parallel to the desired axis, preserving fiber length and enabling the formation of new parts with different aligned geometries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If CFRP parts are pulverized into small chips or powder for reprocessing, then the parts can be refilled into any mold, but the fiber lengths are substantially shortened and fiber alignment is lost
Solution Approach 1:
The patent changes the physical state parameter of the thermoplastic matrix by heating it above its glass transition temperature, transforming it from a rigid state to a compliant state. This allows the matrix to deform and realign fibers without breaking them, while maintaining fiber length and enabling adaptation to different mold geometries.
2Loss of substance
If polymer chains are removed through chemical or pyrolysis methods to salvage carbon fibers, then fiber recovery is achieved, but the process is energy-intensive and fiber quality is degraded
Solution Approach 1:
The patent changes the thermal parameter of the thermoplastic matrix by heating it to a temperature above its glass transition temperature but below decomposition temperature. This selective heating softens the matrix for fiber realignment while preserving both the matrix and fiber integrity, avoiding energy-intensive pyrolysis and chemical treatments.
3Strength
If fibers are realigned into unidirectional preforms through heating and force application, then fiber alignment and mechanical properties are improved, but the process complexity increases
Solution Approach 1:
The patent applies dynamic force vectors to the heated composite part, allowing the material to flow and realign fibers in the direction of applied force. The forces are applied during the heating process when the matrix is compliant, enabling fiber realignment without requiring complex post-processing equipment.
Solution Approach 2:
The patent utilizes the phase transition of the thermoplastic matrix at its glass transition temperature, where the material transitions from a rigid glassy state to a compliant rubbery state. This phase change enables fiber realignment under applied forces, and subsequent cooling reverses the transition to lock in the new fiber orientation.
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 method extends the life cycle of high-performance structural components by maintaining fiber length and allowing for the creation of new parts with superior mechanical properties, overcoming the limitations of existing reprocessing techniques.
Implementation Method 1
heating the composite part to a temperature above a glass transition temperature and below a melting temperature of the thermoplastic resin
Implementation Method 2
applying at least one force vector to the composite part, the sum of the force vectors being parallel to the determined axis, wherein fibers of the composite part realign in a direction generally parallel to the sum of the force vectors
Data Source
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AI summary
A method of reprocessing a fiber composite part to form a preform is provided including determining a location having a longest stretch of continuous, unidirectional fibers in the part, determining an axis generally closest to and parallel to the fibers at the location, suspending the part from an anchor point within a heated cavity, heating the part to a temperature above a glass transition temperature and below a melting temperature of the resin of the part, and applying at least one force vector to the composite part, the sum of such vectors being parallel to the axis, wherein fibers of the part realign in a direction generally parallel to the sum of the force vectors, and wherein the composite part yields in the direction of the at least one applied force vector to provide a preform.