Laminated Ball Joint for Aircraft Vibration Decoupling
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Solution Overview
Problem
Rotary wing aircraft experience significant solidborne noise and vibration, particularly from main transmission gearboxes, which affect occupant comfort, structural integrity, and maximum speed, with existing solutions failing to adequately attenuate high-frequency noise effectively.
Innovation Solution
A laminated ball joint is designed with specific shape, dimension, and physical-property parameters to selectively decouple solidborne noise and vibration by allocating frequency bands for decoupling, using finite element modeling and contextual data to optimize static and dynamic stiffness, damping, and material properties, ensuring high-frequency noise filtration and structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional rigid suspension bars are used to connect the gearbox to the force transmission structure, then structural strength and reliability are improved, but solidborne noise and vibration transmission increase
Solution Approach 1:
The suspension bar employs a composite structure combining a rigid outer shell with viscoelastic damping material. The rigid shell maintains structural strength and load-bearing capacity, while the viscoelastic material absorbs and dissipates vibration energy, reducing solidborne noise transmission to the force transmission structure.
Solution Approach 2:
The patent modifies the physical parameters of the suspension bar by incorporating materials with specific viscoelastic properties that change with frequency and temperature. This allows the bar to exhibit different mechanical characteristics under different operating conditions, optimizing both structural integrity and vibration attenuation.
2Object-generated harmful factors
If damping materials are added to reduce vibration, then solidborne noise is attenuated, but device complexity increases
Solution Approach 1:
The damping function is merged directly into the suspension bar structure itself rather than being a separate component. The viscoelastic material is integrated within the bar's construction, combining the suspension and damping functions into a single unified element, thereby reducing overall system complexity.
Solution Approach 2:
The suspension bar utilizes a flexible shell structure incorporating viscoelastic material that can deform to absorb vibrations. This flexible approach provides effective damping without requiring complex rigid mechanisms or multiple separate damping components.
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 solution effectively attenuates solidborne noise and vibration across targeted frequency bands, enhancing occupant comfort, reducing structural stress, and maintaining aircraft performance while meeting safety and certification standards.
Implementation Method 1
at least two damper layers (19) and one interleaved rigid layer (20)
Implementation Method 2
two damper layers (19) and one interleaved rigid layer (20) which are arranged to be dedicated to frequency bands for decoupling
Data Source
AI summary
Solidborne noise and vibration is decoupled in a rotary wing aircraft by a laminated ball joint (15) for a suspension bar (13) of a transmission gearbox, the ball joint including at least two damper layers (19) dedicated to a frequency band for decoupling in the range 0 to 7000 Hz. For this purpose, the damper layers (19) and possibly also likewise dedicated interleaved layers (20) are given shape and/or dimension and/or physical-property parameters as a function of the frequency for decoupling in the determined frequency band.