Viscoelastic Internally Damped Gear for Resonance Mitigation
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Solution Overview
Problem
Gear vibrations in systems like gas turbine engines can lead to damaging resonant conditions, and existing solutions such as redesigning geometry or adding friction dampers are limited by design space and require careful tuning to avoid introducing new vibration modes.
Innovation Solution
A damping apparatus and internally damped gear design featuring a cavity filled with a viscoelastic damping material, such as polymers or thermoplastics, which dissipates vibration energy through shear forces, and a manufacturing method that includes apertures for filling and visual verification of the damping material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a friction (ring) damper is added to dissipate vibration energy, then gear vibration is reduced, but the system requires careful tuning to avoid introducing new vibration modes and is limited by design space
Solution Approach 1:
The damping material is nested within the hollow cavity of the gear structure itself, creating an internally damped gear. This eliminates the need for external friction dampers and their associated tuning complexity, while effectively dissipating vibration energy through the viscoelastic material's shear deformation.
Solution Approach 2:
A damping material (viscoelastic polymer) is introduced as an intermediary substance within the gear's hollow cavity. This material acts as a mediator that dissipates vibration energy through shear forces, replacing the need for mechanical friction dampers and their complex tuning requirements.
2Object-affected harmful factors
If the geometry is redesigned to move responding modes out the operating range, then gear vibration is reduced, but the design space is limited
Solution Approach 1:
Instead of changing the gear's geometric parameters (which would consume design space), the invention changes the material parameters by filling the hollow cavity with viscoelastic damping material. This allows vibration reduction without altering the gear's external geometry or consuming additional design space.
Solution Approach 2:
The gear becomes a composite structure combining the metal gear body with viscoelastic damping material in its hollow cavity. This composite construction provides vibration damping capabilities without requiring geometric redesign, preserving design space flexibility for other parameters.
3Object-affected harmful factors
If damping material is added to the gear cavity, then vibration energy is dissipated effectively, but manufacturing complexity increases due to filling and verification requirements
Solution Approach 1:
The manufacturing process incorporates preliminary actions by designing injection apertures and vent apertures that guide the damping material filling process. The staggered aperture arrangement ensures complete cavity filling while providing visual verification, simplifying the overall manufacturing process despite the added damping material.
Solution Approach 2:
The vent aperture provides visual verification of the damping material filling status. As the cavity fills, the visual appearance changes, allowing operators to confirm complete filling without complex inspection equipment, thus maintaining manufacturing simplicity.
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
Effectively reduces vibration amplitudes by dissipating energy via shear forces between the damping material and the gear surfaces, providing a robust and efficient solution that can be tailored to specific operating temperatures, thus mitigating the limitations of existing methods.
Implementation Method 1
a damping material disposed in the main cavity... the damping material comprises a viscoelastic material... dissipates vibration energy through shear forces
Implementation Method 2
dissipates vibration energy through shear forces between the damping material and the gear surfaces
Data Source
Figure 1A~1B
Figure 2
Figure 3A
AI summary
A damping apparatus (100) includes a first sidewall (131; 231) defining a centerline axis (290), a second sidewall (132; 232) disposed coaxial with the first sidewall, a main cavity (140; 240) defined between the first sidewall and the second sidewall, and a damping material (150; 250) disposed in the main cavity.