Aircraft APU Wire Suspension with Elastomeric Damping
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Solution Overview
Problem
Conventional APU suspension systems lead to issues such as wearing, resonances, and damage due to load transmission, and are heavy and inefficient, with rigid struts absorbing tension, compression, and shear loads.
Innovation Solution
An attachment system using structural wires linked to the aircraft fuselage with metallic plates and damping elastomeric material, reducing load paths and weight by only requiring tension loads, and incorporating attachment fasteners and bolts with bearings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rigid struts are used to attach the APU to the fuselage, then the APU is securely supported and isolated from vibrations, but the system becomes heavy and complex
Solution Approach 1:
The patent changes the fundamental parameter of the suspension element from rigid struts to flexible wires. This parameter change allows the system to achieve vibration isolation through the flexibility and elasticity of the wires, eliminating the need for heavy rigid structural components while maintaining APU support and isolation from vibrations.
Solution Approach 2:
The patent replaces the traditional mechanical rigid strut system with a wire-based suspension system. This substitution fundamentally changes the mechanical approach from rigid load-bearing structures to flexible tension-based elements, achieving the same vibration isolation function with significantly reduced weight.
2Strength
If rigid struts absorb tension, compression and shear loads, then the APU is securely mounted, but the system becomes heavier and more complex
Solution Approach 1:
The patent changes the load-bearing parameter from multi-axial (tension, compression, shear) to uniaxial (tension only) by using wires instead of rigid struts. This simplifies the system by eliminating the need for complex structural components designed to handle multiple load types, reducing both weight and complexity while maintaining secure mounting through tension-only wire elements.
Solution Approach 2:
The patent segments the load path into simpler components where wires handle only tension loads, and separate damping elements handle vibration absorption. This segmentation allows each component to be optimized for its specific function, reducing overall system complexity compared to rigid struts that must handle all load types simultaneously.
3Reliability
If conventional suspension systems are used, then the APU is attached to the fuselage, but wearing, resonances and damage occur due to load transmission
Solution Approach 1:
The patent introduces damping elastomeric material as an intermediary element between the wire attachment device and the APU mounting bracket. This intermediary absorbs vibrations and reduces the transmission of harmful loads, preventing wearing, resonances, and damage while maintaining reliable APU attachment through the wire-damping material-bracket system.
Solution Approach 2:
The patent converts the potentially harmful vibration and load transmission into a beneficial damping effect by using elastomeric material. The harmful vibrations are absorbed and dissipated as heat in the damping material, transforming the harmful load transmission into a protective vibration isolation mechanism that prevents damage.
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 configuration results in a lighter system with controlled load paths, reducing weight and minimizing damage, achieving significant weight reduction and improved vibration absorption.
Implementation Method 1
a layer of damping elastomeric material adjacent to the metallic plate, such that the metallic plate is placed between the layer of damping elastomeric material and the aircraft fuselage structure
Implementation Method 2
a layer of damping elastomeric material adjacent to the metallic plate
Data Source
AI summary
An aircraft with an auxiliary power unit attached to the aircraft fuselage via an attachment system. The auxiliary power unit is placed inside the aircraft fuselage structure. The attachment system comprises a plurality of structural wires that link the auxiliary power unit to the aircraft fuselage structure. An attachment device is located at the end of each structural wire to connect the structural wire to the aircraft fuselage structure. Each attachment device comprises a metallic plate adjacent to the aircraft fuselage structure and a layer of damping elastomeric material adjacent to the metallic plate. The metallic plate is placed between the layer of damping elastomeric material and the aircraft fuselage structure. The attachment device is joined to the aircraft fuselage structure by attachment fasteners.