Aircraft Door Transmission Rod Resonance Control for Noise Reduction
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Solution Overview
Problem
Aircraft doors with transmission rods often generate perceivable vibration noise due to the vibration of these rods during flight or on the ground, leading to a feeling of poor quality.
Innovation Solution
An aircraft door equipped with an anti-vibration device mounted to the transmission rod, which absorbs vibrations and modifies the resonance frequency of the rod to reduce noise perception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If transmission rods are used in the door opening system, then the locking function is achieved, but vibration noise is generated during operation
Solution Approach 1:
A vibration absorber is introduced as an intermediary component between the transmission rod and the door structure. This absorber contains a viscoelastic material that mediates the vibration transmission, converting mechanical vibration energy into heat through internal friction, thereby reducing the harmful vibration noise while maintaining the locking function
Solution Approach 2:
The vibration absorber changes the dynamic parameters of the transmission rod system by adding mass and damping characteristics. The viscoelastic material's loss factor and stiffness are specifically selected to modify the natural frequency and damping ratio of the transmission rod, shifting the resonance characteristics away from operational frequencies and reducing vibration amplitude
2Object-generated harmful factors
If vibration absorber is added to the transmission rod, then vibration noise is reduced, but device complexity increases
Solution Approach 1:
The vibration absorber is designed as a nested structure where the viscoelastic material is contained within a housing that attaches to the transmission rod. This nested design allows the vibration absorption functionality to be integrated into the existing transmission rod assembly without requiring separate mounting structures or complex external components
Solution Approach 2:
The vibration absorber utilizes a flexible viscoelastic material that can be molded into thin-walled structures. This flexible material provides effective vibration damping while maintaining a compact, lightweight design that does not significantly increase the overall size or complexity of the door opening system
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 anti-vibration device significantly reduces perceivable vibration noise during door closure and flight, enhancing the quality of the aircraft door without requiring structural modifications or complex kinematic analyses.
Implementation Method 1
The vibration absorber has a housing and a vibration damping element arranged in the housing. The vibration damping element has a loss factor which is at least 0.05 and at most 0.50 and a stiffness which is at least 10 kN/m and at most 1000 kN/m
Implementation Method 2
The anti-vibration device is mounted in the inner door space to the at least one transmission rod for absorbing vibrations of the at least one transmission rod
Data Source
AI summary
An aircraft door with an inner door space; a door opening system arranged at least partly in the inner door space. The door opening system comprises: at least one locking device for locking the aircraft door in a locked state, actuation kinematics for actuating the at least one locking device, and at least one transmission rod coupling the actuation kinematics with the at least one locking device; wherein the at least one transmission rod is displaceable in the inner door space by means of the actuation kinematics for actuating the at least one locking device; and an anti-vibration device mounted in the inner door space to the at least one transmission rod for absorbing vibrations of the at least one transmission rod, wherein the anti-vibration device is displaceable in the inner door space together with the at least one transmission rod.