Non-Metallic Outflow Valve Frame Attachment Under Thermal Deflection

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Solution Overview

Problem

The challenge lies in designing an outflow valve assembly with a non-metallic frame that can maintain reliable and durable attachment interfaces with metallic components while accommodating fuselage deflection and thermal extremes, as traditional metallic frames face issues with material creep and deformation over time.

Innovation Solution

The outflow valve assembly incorporates a non-metallic frame made from materials like carbon fiber-loaded PEEK, featuring enhanced attachment features such as elevated platform regions, recesses, and raised rims, along with resilient members and leverage mechanisms to maintain fastener preloads and accommodate deflections, and uses compression limiters to prevent stress concentrations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If a non-metallic frame is used to reduce weight and cost, then weight and manufacturing cost are reduced, but the reliability and durability of attachment interfaces deteriorate due to material creep and deformation under thermal cycling

Engineering Contradiction:

Improveframe weightVSAvoidattachment interface reliability

Core Design Contradiction:

Weight of moving objectVSReliability

Solution Approach 1:

The frame is constructed from composite materials (such as carbon fiber-reinforced polymers or other fiber-reinforced plastics) that combine the low weight of non-metallic materials with the high strength and dimensional stability required to maintain reliable attachment interfaces under thermal cycling and mechanical loads

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The attachment interface geometry is modified to include enlarged bearing surfaces, recesses, and protrusions that change the mechanical parameters of the joint, allowing non-metallic frames to maintain fastener preloads and resist deformation under thermal and mechanical stresses

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If a non-metallic frame is used for ease of manufacture and cost savings, then manufacturing complexity and cost are reduced, but the ability to maintain fastener preloads deteriorates due to thermal creep and material deformation

Engineering Contradiction:

Improveframe manufacturing easeVSAvoidfastener preload maintenance

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The frame includes pre-formed attachment features such as recesses, protrusions, and enlarged bearing surfaces that are integrated into the molded frame structure, establishing proper fastener alignment and preload distribution before assembly, thereby compensating for thermal creep and material deformation

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The attachment interface geometry is modified to include features that change the mechanical parameters of the joint, allowing non-metallic frames to maintain fastener preloads and resist deformation under thermal and mechanical stresses

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If the frame is designed with sufficient flexibility to accommodate fuselage deflection, then adaptability to fuselage movement is improved, but the strength and resistance to material overstress deteriorate

Engineering Contradiction:

Improvefuselage deflection accommodationVSAvoidresistance to material overstress

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The frame is divided into multiple sections or segments that can flex independently to accommodate fuselage deflection, while each segment maintains sufficient strength through optimized cross-sectional geometry and material distribution

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Composite materials with tailored fiber orientations and material properties are used to create regions of the frame that provide both flexibility for fuselage deflection accommodation and localized strength to resist material overstress

Inventive Principle:

Principle #40Composite materials

4Reliability

If traditional metallic frames are used for strength and reliability, then attachment interface durability is improved, but weight and manufacturing cost increase

Engineering Contradiction:

Improveattachment interface durabilityVSAvoidframe weight

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

Inventive Principle:

Principle #40Composite materials

Data Source

PatentEP3693275B1Outflow valve assemblies including non-metallic frames and enhanced attachment features

Publication Date: 2022.03.30 HONEYWELL INTERNATIONAL INC

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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.