Non-Metallic Outflow Valve Attachment for Thermal Cycling Loads
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Solution Overview
Problem
The challenge lies in designing cabin outflow valve assemblies with non-metallic frames that can maintain reliable attachment interfaces with metallic components while accommodating fuselage deflection and thermal extremes, as traditional thermoplastic frames tend to deform and lose preload over time, leading to reduced longevity and increased material stress.
Innovation Solution
The implementation of enhanced attachment features such as elevated platform regions, resilient members, and compression limiters in the non-metallic OFV frame, which are integrated into the frame design to maintain fastener preload and accommodate deflection, and the use of metallic inserts to distribute stress, ensuring secure attachment to the aircraft fuselage and other components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a non-metallic thermoplastic frame is used to reduce weight and cost, then weight and manufacturing cost are reduced, but the frame loses the ability to maintain fastener preload due to creep and thermal deformation
Solution Approach 1:
The patent employs composite materials, specifically carbon fiber-reinforced PEEK (polyether ether ketone), to construct the non-metallic frame. This composite material provides both the weight reduction benefits of non-metallic materials and the structural stability needed to maintain fastener preload under thermal cycling and mechanical loads, directly resolving the contradiction between weight reduction and joint reliability
Solution Approach 2:
The patent modifies the physical and mechanical parameters of the thermoplastic material by incorporating carbon fiber reinforcement, which significantly enhances the material's creep resistance, thermal stability, and stiffness. This parameter change allows the frame to maintain fastener preload despite thermal cycling and mechanical stresses
2Ease of manufacture
If traditional thermoplastic materials are used for the frame, then ease of manufacture and cost are improved, but material over-stress and fatigue occur when securing to the fuselage and attaching components
Solution Approach 1:
The use of carbon fiber-reinforced PEEK composite material provides both the ease of molding associated with thermoplastics and the enhanced strength required to withstand securing forces to the fuselage and component attachment loads, eliminating material over-stress and fatigue issues
Solution Approach 2:
The patent incorporates metallic inserts at specific locations where high strength is required for securing to the fuselage and attaching heavy components. These localized metallic reinforcement elements provide the necessary strength at critical stress points while maintaining the overall non-metallic frame construction
3Stability of the object's composition
If the frame is made rigid to maintain attachment integrity, then joint stability is improved, but the frame cannot accommodate significant fuselage deflection
Solution Approach 1:
The patent designs the non-metallic frame with inherent flexibility to dynamically accommodate fuselage deflection during flight. The composite material and frame geometry are engineered to allow controlled elastic deformation, enabling the frame to adapt to fuselage shape changes while maintaining secure attachment through the flexibility of the non-metallic construction
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 solution enables the production of lightweight, cost-effective non-metallic OFV frames that maintain joint integrity over extended periods, reducing material fatigue and stress, while allowing for significant fuselage deflection and exposure to thermal cycling, thus enhancing the reliability and longevity of the valve assembly.
Implementation Method 1
as the thermoplastic (or other non-metallic) frame material creeps, reflows, or otherwise deforms with thermal cycling over time
Implementation Method 2
as the thermoplastic (or other non-metallic) frame material creeps, reflows, or otherwise deforms with thermal cycling over time
Implementation Method 3
The frame attachment interfaces include fastener openings and elevated platform regions, which project from an inboard side of the outer peripheral flange and through which the fastener openings extend
Implementation Method 4
the OFV frame is generally required to possess sufficient flexibility to accommodate significant fuselage deflection
Data Source
AI summary
Outflow valve (OFV) assemblies including non-metallic frames and enhanced attachment features are provided. In embodiments, the OFV assembly includes a non-metallic frame to which at least one valve door is pivotally mounted. The non-metallic frame may, in turn, include a generally rectangular frame body, a central opening through the frame body, an outer peripheral flange extending around at least a portion of the frame body. Frame attachment interfaces are distributed or spaced around the outer peripheral flange of the non-metallic frame. The frame attachment interfaces include fastener openings and elevated platform regions, which project from an inboard side of the outer peripheral flange and through which the fastener openings extend. Base plates seat against the elevated platform regions. Fasteners engage the base plates and extend through the fastener openings to an outboard side of the outer peripheral flange to attach the OFV assembly to an aircraft fuselage.