Fusible Engine Mount Assembly for Peak Load and Vibration Isolation
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Solution Overview
Problem
Existing mounting assemblies for gas turbine engines fail to effectively mitigate the adverse effects of severe unbalances and vibrations caused by failure events, such as fan or turbine blade breakage, leading to potential detachment and transmission of peak transient dynamic loads to the aircraft.
Innovation Solution
A mounting assembly with a fusible component and a catcher component having different shear strengths, allowing for a relative movement between the engine and pylon during failure events, thereby limiting peak transient dynamic loads and isolating vibrations through a nonlinear stiffness characteristic.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the mounting assembly uses a rigid connection between the engine and pylon, then the structural strength and stability are improved, but the transmission of peak transient dynamic loads and vibrations to the aircraft increases during failure events
Solution Approach 1:
The mounting assembly incorporates a fusible component that can transition from a rigid load-bearing state to a failed state with different mechanical properties. This dynamic transition allows the system to adapt its stiffness characteristics based on operational conditions, providing rigid support during normal operation and isolating vibrations during failure events through controlled mechanical failure of the fusible component.
Solution Approach 2:
The system changes its mechanical parameters (stiffness, load path) through the controlled failure of the fusible component. Before failure, the fusible component provides a rigid connection with high structural strength. After failure, the change in mechanical properties of the fusible component creates a nonlinear stiffness characteristic that limits peak transient dynamic loads while maintaining connection integrity through the catcher component.
2Reliability
If the mounting assembly is designed to withstand severe unbalance loads, then the reliability under failure conditions is improved, but the weight and cost of the gas turbine engine increases
Solution Approach 1:
The mounting assembly is segmented into distinct functional components: a load-bearing component for normal operation, a fusible component for controlled failure, and a catcher component for post-failure support. This segmentation allows each component to be optimized for its specific function, enabling the system to achieve high reliability under failure conditions without requiring the entire assembly to be over-engineered, thus reducing overall weight and cost.
Solution Approach 2:
The fusible component acts as an intermediary element between the rigid mounting structure and the flexible response required during failure events. This intermediary component enables controlled mechanical failure that transitions the system from a rigid to a more compliant state, allowing vibration isolation and peak load limitation without requiring the main structural components to be designed for extreme failure loads, thereby reducing weight and cost.
3Device complexity
If the mounting assembly provides a linear stiffness characteristic, then the structural simplicity is maintained, but the ability to limit peak transient dynamic loads and isolate vibrations during failure events is reduced
Solution Approach 1:
The system transitions from a static, linear stiffness characteristic to a dynamic, nonlinear stiffness characteristic through the controlled failure of the fusible component. This dynamic change enables the mounting assembly to provide different mechanical responses for different operational states: rigid support during normal operation and vibration isolation during failure events, achieving complex behavior through a relatively simple structural modification.
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 assembly reduces adverse effects of engine unbalances on the aircraft by limiting peak transient dynamic loads and isolating vibrations, enabling reduced weight and cost of the gas turbine engine while maintaining robustness and independent design flexibility for different engines.
Implementation Method 1
The fusible component has a first shear strength. When an applied shear stress on the fusible component exceeds the first shear strength of the fusible component, the fusible component mechanically fails
Implementation Method 2
the mounting assembly may provide a nonlinear stiffness characteristic between the gas turbine engine and the pylon along the first axis. Specifically, in the second state of the mounting assembly, the mounting assembly may limit the peak transient dynamic loads and isolate engine vibrations
Data Source
AI summary
A mounting assembly includes an engine mount link, an engine mount block, a fusible component, and a catcher component. The engine mount block is connected to a pylon and the engine mount link. The fusible component and the catcher component have respective first and second shear strengths. The catcher component is disposed within a catcher aperture. When an applied shear stress on the fusible component is less than the first shear strength, the engine mount link is stationary with respect to the engine mount block. When the applied shear stress on the fusible component exceeds the first shear strength, the fusible component mechanically fails and causes the catcher component to move relative to the catcher aperture further causing a corresponding movement of the engine mount link.