Composite Re-entrant Angle Manufacturing via Layer Slippage
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Solution Overview
Problem
The existing methods for producing composite aircraft fuselage frames with re-entrant angles face challenges in layer stacking, leading to bridging defects and fiber undulations due to inter-layer shear stresses and decreased adhesion at concave surfaces, which compromise the mechanical properties of the final component.
Innovation Solution
A method involving pre-impregnated fiber layers that allows slipping between layers during a polymerization cycle, with a temperature soak at a threshold temperature (Tf) before the pressure-increase phase, enabling uniform temperature distribution and preventing wrinkling by allowing layers to slide and eliminate excess fiber lengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If layers are stacked with high pressure to ensure contact across entire width, then manufacturing precision improves, but inter-layer shear stresses increase causing fiber undulations and bridging defects
Solution Approach 1:
The patent applies parameter changes by controlling temperature to exceed the gel point of the resin, transforming the resin from a rigid state to a fluid state. This allows layers to slip relative to each other during compression, eliminating inter-layer shear stresses and preventing fiber undulations while maintaining good contact across the entire width of the profile.
Solution Approach 2:
The patent introduces dynamic behavior by allowing layers to move (slip) relative to each other during the compression process when temperature is elevated. This dynamic slippage prevents the formation of bridging defects and fiber undulations, while the layers eventually settle into proper contact positions as the resin cures.
2Manufacturing precision
If temperature is increased to allow layer slippage and eliminate undulations, then manufacturing precision improves, but energy consumption increases
Solution Approach 1:
The patent uses parameter changes by carefully controlling temperature to reach but not excessively exceed the gel point. This optimized temperature parameter allows sufficient slippage to eliminate undulations while minimizing energy consumption. The temperature is maintained at this critical threshold throughout the compression process, then gradually reduced as curing progresses.
Solution Approach 2:
The patent applies periodic action through a multi-stage temperature profile: initial heating to the gel point, maintenance at this threshold during compression, and gradual cooling as curing completes. This periodic temperature control optimizes both fiber alignment and energy efficiency by avoiding continuous high-temperature exposure.
3Manufacturing precision
If compression pressure is applied during polymerization to ensure layer contact, then manufacturing precision improves, but fiber undulations occur due to inter-layer shear stresses
Solution Approach 1:
The patent resolves this contradiction by changing the temperature parameter to exceed the gel point during compression. This transforms the resin from rigid to fluid, allowing layers to slip and eliminating inter-layer shear stresses that would otherwise cause fiber undulations. Good contact is maintained through the fluid state, then固化 locks the layers in place.
Solution Approach 2:
The patent introduces dynamic slippage between layers during compression when temperature is elevated, allowing the system to adapt to the compression forces without generating harmful shear stresses. This dynamic behavior prevents fiber undulations while maintaining proper layer contact, then the system freezes as the resin cures.
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 reduces fiber undulations and bridging defects, ensuring firm contact and improved mechanical properties of the composite component by allowing layers to slip and align properly during polymerization, enhancing the structural integrity of the fuselage frames.
Implementation Method 1
a polymerization cycle comprising a temperature cycle with a temperature-increase phase and at least on soak at which the temperature is maintained
Implementation Method 2
a temperature-increase phase and at least on soak at which the temperature is maintained, the layers of pre-impregnated fibres being able to slip against one another when the temperature of the temperature cycle is equal to or higher than a threshold temperature Tf dependent on the resin
Data Source
AI summary
A method for producing, in a composite material, a component that has a re-entrant angle, includes stacking layers of fibers which have been pre-impregnated with a resin so as to obtain a preform and placing the preform in a tooling fixture in order to subject it to a polymerization cycle including a temperature cycle, with a temperature-increase phase and at least one soak at which the temperature is maintained, and a pressure cycle on the outside of the tooling fixture with a pressure-increase phase and a pressure-hold phase, with the layers of pre-impregnated fibers being able to slip against one another when the temperature of the temperature cycle is equal to or higher than a threshold temperature Tf dependent on the resin. The temperature-increase phase includes a soak at a temperature higher than or equal to Tf, the soak beginning before the end of the pressure-increase phase.