Frangible Gearbox Guide Support for Fan Blade Out Loads
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Solution Overview
Problem
Conventional mounting systems for auxiliary components in gas turbine engines are unable to withstand high shock loads from fan blade out events, leading to potential separation or damage of auxiliary components like gearboxes due to rotor imbalance.
Innovation Solution
A gearbox mounting system incorporating a frangible ring member made of porous metal material, which is designed to deform and absorb energy during an overload event, limiting motion and reducing the risk of damage to auxiliary components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional mounting systems are used to mount auxiliary components to the engine case, then the components can be securely attached during normal operation, but the mounting system cannot withstand high shock loads from fan blade out events, causing separation or damage of auxiliary components
Solution Approach 1:
The frangible ring member is pre-installed in the mounting system between the support bracket and bearing member, creating a built-in energy absorption mechanism that activates during overload events. This beforehand cushioning allows the system to withstand shock loads by permitting controlled deformation of the porous metal structure, preventing catastrophic failure of the entire mounting system while protecting auxiliary components during FBO events
Solution Approach 2:
The patent utilizes parameter changes in the porous metal material's density and compressive strength characteristics. The frangible ring member is designed with specific porosity parameters that allow it to deform at predetermined load thresholds. During normal operation, the ring maintains sufficient rigidity, but under shock loads, the porous structure collapses in a controlled manner, changing its mechanical parameters to absorb energy and protect the mounting system
2Weight of moving object
If light-weight materials are used in gearbox hardware to reduce aircraft weight, then the aircraft weight is reduced, but the gearbox materials may not be sufficiently strong to withstand FBO loads
Solution Approach 1:
The frangible ring member is constructed from porous metal material with controlled porosity, providing an optimal balance between weight reduction and mechanical performance. The porous structure reduces the ring's weight while maintaining sufficient strength for normal operation. During FBO events, the porous structure's controlled collapse absorbs energy, compensating for the reduced material strength and enabling the use of lighter materials in the overall gearbox assembly
Solution Approach 2:
The mounting system employs a composite approach by combining the frangible ring member made of porous metal material with other mounting components. This composite system allows different parts to have optimized material properties - the frangible ring uses lightweight porous material for energy absorption, while other components maintain higher strength requirements, achieving overall weight reduction without compromising the gearbox's ability to withstand FBO loads
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 system effectively absorbs energy from fan blade out events, preventing damage to auxiliary components and maintaining their attachment to the engine case, while providing a lightweight and cost-effective solution.
Implementation Method 1
the frangible ring member comprises a porous metal material configured to deform to permit movement between the support bracket and the auxiliary component following an overload event
Implementation Method 2
the porous metal material is configured to collapse in response to the overload event
Data Source
AI summary
An assembly for mounting an auxiliary component to an engine case of a gas turbine engine includes a support bracket, the support bracket having a first end configured for attachment to a first flange of the engine case, a second end configured for attachment to a second flange of the engine case, and an intermediate portion located intermediate the first end and the second end; a bearing member disposed within the intermediate portion; a locator disposed within the bearing member; and a frangible ring member disposed between the support bracket and the bearing member, wherein the frangible ring member comprises a porous metal material (e.g., frothed aluminum or thin-walled honey combed aluminum or steel). The frangible material thickness can be set to absorb FBO energy while limiting system displacement during and post FBO event, thus reducing the energy transmitted to an auxiliary component (e.g., a gearbox housing).