Composite Beam Joint Assembly for Lower Seat Frame Stress
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Solution Overview
Problem
Existing aircraft seat designs using composite materials face challenges in efficiently joining composite beams to seat frames, leading to stress concentrations and potential cracks, while also being heavy and costly.
Innovation Solution
A joint connector assembly is introduced, featuring a metallic ring connector coupled with tubular composite beams and an elastomeric layer to reduce local stress concentrations, using materials like natural or synthetic rubber to absorb energy and minimize weight and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If composite beams are joined directly to seat frames using metallic connectors, then structural strength is improved, but stress concentrations and potential cracks occur
Solution Approach 1:
An elastomeric layer is introduced as an intermediary component between the metallic ring connector and the tubular composite beam. This elastomeric layer acts as a stress-distributing mediator that prevents direct stress concentration at the interface, thereby maintaining structural strength while improving reliability by eliminating crack initiation points.
Solution Approach 2:
The joint connector assembly utilizes a composite structure combining metallic materials (ring connector) with elastomeric materials (intermediate layer). This composite approach leverages the high strength of metals while incorporating the stress-distributing properties of elastomers, resolving the contradiction between strength and stress concentration resistance.
2Reliability
If traditional joining methods are used for composite beams, then structural integrity is maintained, but weight and cost increase
Solution Approach 1:
The elastomeric layer is a relatively simple, lightweight component that can be easily replaced if needed. It provides essential stress-distribution functionality without the weight penalty of complex metallic joining structures, thereby reducing overall seat weight while maintaining structural integrity.
Solution Approach 2:
The elastomeric layer functions as a flexible intermediate film that distributes stresses across the interface between the rigid metallic connector and composite beam. This thin flexible layer maintains structural integrity without adding significant weight, unlike traditional heavy metallic joining methods.
3Strength
If metallic connectors are used to join composite beams, then connection strength is improved, but local stress concentrations occur on the composite beams
Solution Approach 1:
The elastomeric layer serves as a stress-distributing intermediary between the metallic ring connector and the composite beam. It maintains the strong mechanical connection provided by the metal while transforming concentrated contact stresses into distributed stresses across the elastomeric material, thereby eliminating local stress concentrations on the composite beam.
Solution Approach 2:
The elastomeric material changes the stress distribution parameters at the interface by its compliant properties. It transforms the stress field from a concentrated pattern (without elastomer) to a distributed pattern (with elastomer), thereby maintaining connection strength while reducing local stress concentrations that lead to cracking.
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
The assembly effectively reduces stress concentrations, meets aviation standards, and minimizes the risk of damage, while reducing the overall weight and cost of the aircraft seat.
Implementation Method 1
a layer arranged between an internal surface of the metallic ring connector and an external surface of the one or more tubular composite beams, where the layer is formed of a material configured to reduce local stress concentrations
Data Source
Figure 1A~1B
Figure 2A
Figure 2B
AI summary
A joint connect assembly may include a metallic ring connector (304) configured to couple with one or more tubular composite beams (222). The joint connect assembly may include a layer (302) arranged between the metallic ring connector and an external surface of the one or more tubular composite beams. The layer may be formed of a material configured to reduce local stress concentrations on the one or more tubular composite beams. The material of the layer may be an elastomeric material, e.g., the layer may include at least one of a natural rubber, synthetic rubber, or a combination thereof.