Gearbox Mounting Bracket With Frangible Ring for FBO Loads
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Solution Overview
Problem
Conventional mounting systems for auxiliary components in gas turbine engines, such as gearboxes, are unable to withstand the high shock loads caused by fan blade out events, leading to potential separation or damage due to inadequate strength and durability, particularly under rotor imbalance loads.
Innovation Solution
A gearbox mounting system incorporating a frangible ring member made of porous metal material, such as metal foam or honeycomb structure, 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
1Strength
If conventional mounting systems are used to mount auxiliary components to the engine case, then the system is simple and lightweight, but the mounting system cannot withstand high shock loads from fan blade out events, causing separation or damage to auxiliary components
Solution Approach 1:
The mounting system is segmented into multiple functional components: a support bracket for mounting the auxiliary component, a frangible ring member with porous metal material, and a bearing member. The frangible ring member is positioned between the support bracket and bearing member, allowing the system to absorb shock loads through controlled deformation of the porous material while maintaining overall structural integrity.
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 fan blade out loads
Solution Approach 1:
The frangible ring member is made of porous metal material that provides an optimal balance between weight and strength. The porous structure reduces the weight of the mounting system while maintaining sufficient strength to support auxiliary components during normal operation. During fan blade out events, the porous structure absorbs impact energy through controlled collapse, protecting the auxiliary components.
3Reliability
If the mounting system is designed to withstand high shock loads, then auxiliary components are protected from damage, but the mounting system becomes overly strong and heavy
Solution Approach 1:
The frangible ring member is deliberately designed with controlled weakness through its porous structure, allowing it to fail in a predictable manner during fan blade out events. This controlled failure absorbs the harmful shock loads, protecting the more valuable auxiliary components. The porous material's ability to collapse and absorb energy converts the harmful impact into beneficial energy dissipation.
4Force
If conventional rigid mounting systems are used, then the auxiliary components are securely mounted, but the shock loads are transferred to the auxiliary components causing damage
Solution Approach 1:
The frangible ring member with porous metal material is pre-positioned between the support bracket and bearing member to provide cushioning before impact occurs. The porous structure is designed to absorb and dissipate shock loads through controlled deformation, preventing the transfer of harmful forces to the auxiliary components during fan blade out events.
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 during a fan blade out event, preventing excessive motion and potential damage to the gearbox, while maintaining the component's attachment to the engine case, thus enhancing the system's ability to withstand rotor imbalance loads without over-building the hardware.
Implementation Method 1
a frangible ring member disposed between the support bracket and the bearing member, wherein the frangible ring member comprises a porous metal material configured to collapse in response to the overload event
Data Source
Figure 1A
Figure 1B
Figure 2A~2B
AI summary
An assembly (200) for mounting an auxiliary component to an engine case (110) of a gas turbine engine (100) includes a support bracket (122), the support bracket having a first end (230) configured for attachment to a first flange (232) of the engine case, a second end (236) configured for attachment to a second flange (238) of the engine case, and an intermediate portion (246) located intermediate the first end and the second end; a bearing member (248) disposed within the intermediate portion; a locator (224) disposed within the bearing member; and a frangible ring member (260) 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 (262) 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 (120)).