Braided Preform Pulsed-Pressure Consolidation Against Shear Lock
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Solution Overview
Problem
Braided composite parts face challenges during consolidation due to shear lock and friction locking issues at fiber intersections, leading to uneven or out-of-tolerance results, necessitating reworking or discarding of the composite parts.
Innovation Solution
The method involves pulsed-pressure consolidation of braided preforms using an inflatable bladder within a mandrel, iteratively increasing and decreasing pressure to relax locked areas, allowing for continued consolidation without shear locking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If consolidation pressure is applied to braided preforms, then consolidation of the composite part is achieved, but shear lock and friction locking occur at fiber intersections causing uneven consolidation
Solution Approach 1:
The patent applies periodic pulsed pressure cycles during consolidation, where pressure is applied and then released in repeated cycles. This periodic action allows fiber intersections to relax during pressure release phases, preventing permanent shear lock and friction locking, while still achieving progressive consolidation over multiple cycles.
Solution Approach 2:
The patent changes the pressure parameter dynamically by applying pulsed pressure cycles with varying magnitude and duration. By modulating the pressure parameter rather than applying constant pressure, the process prevents fiber lockup while maintaining consolidation progress through cumulative deformation.
2Manufacturing precision
If high consolidation force is applied to prevent shear locking, then consolidation quality improves, but fiber damage and out-of-tolerance deformation increase
Solution Approach 1:
By using periodic pressure pulses rather than sustained high force, the system achieves consolidation quality through cumulative effect while allowing fiber relaxation during off-pressure phases, preventing permanent damage and out-of-tolerance deformation.
Solution Approach 2:
The consolidation process transitions from static constant pressure to dynamic pulsed pressure, allowing the system to adapt to fiber intersection behavior in real-time and prevent damage through controlled pressure variation.
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 prevents shear locking, ensuring even consolidation and reducing the likelihood of out-of-tolerance composite parts, enhancing fabrication efficiency and reducing costs by allowing for the production of high-strength composite parts like fuel-feed tubes for aircraft.
Implementation Method 1
iteratively applying pressure to the braided preform via the bladder to consolidate the braided preform against the mandrel
Implementation Method 2
areas within a weave that have encountered a friction lock or a shear lock relax, releasing the lock and enabling consolidation to continue during a next application of pressure
Data Source
AI summary
Systems and methods are provided for consolidating a preform of braided fiber. One embodiment is a method that includes acquiring a braided preform comprising fibers of unidirectional material that have been woven into a shape having a closed cross-section, disposing the braided preform within a mandrel, disposing an inflatable bladder within the closed cross-section of the braided preform, and iteratively applying pressure to the braided preform via the bladder to consolidate the braided preform against the mandrel.