Aircraft Engine Mount Damping for Vibration Isolation and Motion Control
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Solution Overview
Problem
Conventional compliant engine mount systems for aircraft face challenges in reducing vibration and force transmission while minimizing the drawbacks of elastomeric materials, such as compression set and creep, which require additional accommodation for motion control and incorporation of snubbing elements to manage undesired motions over time.
Innovation Solution
The proposed engine mount system incorporates a top mount, lower mount, and center trunnion mount with mechanical, elastomeric, and fluidic damping components, featuring a flexing element, fluid-filled cavities, and interlocking linkages with compression and tension stops to isolate vibrations and allow transmission of abnormal forces, utilizing a gas-filled bladder to tune inertial effects and accommodate thermal changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If elastomeric materials are used in compliant mounts to compensate for larger ranges of motion with softer spring rates, then motion control capability is improved, but the materials tend to take compression set and exhibit creep over time, requiring additional accommodation for motion
Solution Approach 1:
The elastomeric element is segmented into multiple layers with different material properties. The first layer has a first modulus of elasticity and the second layer has a second modulus of elasticity, creating a composite structure that balances motion compliance with dimensional stability. This segmentation allows each layer to contribute differently to the overall performance, reducing compression set and creep while maintaining motion control.
Solution Approach 2:
The invention uses a composite elastomeric structure with two distinct layers having different moduli of elasticity. This composite material approach combines the advantages of softer materials (better motion control) with stiffer materials (better dimensional stability), resolving the contradiction between ease of operation and reliability over time.
2Ease of operation
If stops are incorporated in conjunction with elastomers to minimize excess undesired motions, then motion control is improved, but the stops must be set to accommodate the set and creep of elastomeric materials during the life of the mounting system, requiring additional motion control capability
Solution Approach 1:
The elastomeric element is pre-compressed between the first and second stops during assembly, creating a pre-load condition. This beforehand cushioning accounts for future compression set and creep by starting with the elastomer already compressed, so that the stops remain effective throughout the service life without requiring adjustment for material degradation.
Solution Approach 2:
The elastomeric element is pre-compressed during assembly to establish initial contact forces between the stops and the mounting structure. This preliminary action ensures that the stops are properly positioned and that the elastomer is already accounting for its own compression set before service begins, reducing the need for additional motion control capability.
3Ease of manufacture
If a single-layer elastomeric element is used, then manufacturing is simpler, but the element cannot effectively balance motion control with resistance to compression set and creep
Solution Approach 1:
The elastomeric element is divided into multiple manufacturable layers that can be produced using standard molding techniques. Each layer has specific dimensional requirements that are achieved through controlled compression during assembly, making the segmentation practical for manufacturing while delivering the reliability benefits of composite material properties.
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 system effectively isolates the aircraft from vibrations and normal forces while enabling the transmission of abnormal forces, providing improved durability and reduced noise and vibration transmission, with minimal compliance characteristics during abnormal operating conditions.
Implementation Method 1
mechanical, elastomeric, and fluidic damping components
Implementation Method 2
flexing element
Implementation Method 3
utilizing a gas-filled bladder to tune inertial effects
Implementation Method 4
fluidic damping components
Implementation Method 5
accommodate thermal changes
Implementation Method 6
tune inertial effects
Implementation Method 7
at least one compression stop configured to carry loads in compression
Implementation Method 8
at least one tension stop configured to carry loads in tension
Data Source
AI summary
Compliant mounting systems, devices, and methods for mounting a vehicle engine to a vehicle structure or base include a top mount, a lower mount, a center trunnion mount, and an aft mount which are configured to react forces transmitted by the engine to the vehicle structure. Metallic and elastomeric elements can provide vibrational and force isolation characteristics. Stops (e.g., snubbing elements) allow for a specific range of motion before internal mount structures contact each other to act as a conventional hard mount. Fluid elements and compressible gas-filled spaces/bladders may be incorporated to provide fluid damping behaviors to complement the metallic and elastomeric elements.