Tapered Sockets Decouple Torsional and Lateral Stiffness in Engine Mounts
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Solution Overview
Problem
Current engine mount assemblies for aircraft fail to independently control engine motion along various degrees of freedom, such as lateral, vertical, and torsional directions, due to coupled stiffness in torsional and lateral directions, leading to structural instability and difficulty in meeting operational vibration targets.
Innovation Solution
The engine mount assembly incorporates a torsion bar with a tapered boss and arm assembly, including an end bell crank with a tapered socket, allowing independent control of engine movement by decoupling torsional and lateral stiffness, and utilizing a scissor mount and linkage system to manage vertical movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If current engine mounts are used with coupled stiffness design, then structural simplicity is maintained, but independent control of engine movement in different directions is lost
Solution Approach 1:
The engine mount assembly is segmented into multiple independent functional components: a torsion bar for torsional movement control, lateral movement control assemblies with bell cranks for lateral direction, and vertical movement control assemblies for vertical direction. Each segment handles a specific degree of freedom independently, allowing independent tuning of stiffness in each direction while maintaining overall structural coherence.
2Reliability
If stiffness in torsional direction is increased, then torsional vibration is reduced, but lateral stiffness is also affected due to coupling
Solution Approach 1:
The coupling between torsional and lateral stiffness is eliminated by segmenting the load paths. The torsion bar independently handles torsional loads, while the lateral movement control assemblies with bell cranks independently handle lateral loads. This segmentation allows the stiffness in each direction to be tuned independently without affecting the other directions, resolving the contradiction between vibration control and independent stiffness tuning.
3Stability of the object's composition
If engine movement is constrained in multiple directions, then structural stability is improved, but ability to absorb vibrations is reduced
Solution Approach 1:
The engine mount assembly incorporates dynamic elements that allow controlled movement and vibration absorption while maintaining stability. The bell cranks are designed to rotate within specific arcs, the torsion bar provides torsional flexibility, and the linkages allow vertical movement. These dynamic characteristics enable the system to absorb engine vibrations and oscillatory loads while maintaining structural stability through the coordinated action of multiple control assemblies.
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 design enables independent tuning of stiffness in each direction, reducing oscillatory loading and vibration, and effectively manages engine movement in multiple degrees of freedom without affecting other directions, thereby enhancing structural stability and meeting operational vibration targets.
Implementation Method 1
The tapered socket is adapted to receive the tapered boss on the end of the torsion bar to secure the end bell crank to the torsion bar
Implementation Method 2
The tapered socket is adapted to receive the tapered boss on the end of the torsion bar to secure the end bell crank to the torsion bar
Implementation Method 3
A torsion bar coupled between the engine and the airframe. The torsion bar has an end including a tapered boss
Implementation Method 4
secure the end bell crank to the torsion bar such that the end bell crank rotates with the torsion bar responsive to movements of the engine
Data Source
AI summary
An engine mount assembly for coupling an engine to an airframe. The engine mount assembly includes a torsion bar coupled between the engine and the airframe. The torsion bar has upper and lower tapered bosses. Upper and lower arm assemblies couple the engine to the torsion bar. Each arm assembly has an end bell crank with a tapered socket that is adapted to receive a respective tapered boss therein to secure the end bell cranks to the torsion bar such that the end bell cranks rotate with the torsion bar responsive to movements of the engine.