Dual Arm V Brackets for CMC Annular Members
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Solution Overview
Problem
Gas turbine engine annular members made of materials with different thermal expansion coefficients, such as ceramic matrix composite (CMC) and metallic materials, face challenges in connection and support due to their disparate expansion rates and the brittleness of CMC materials in high-temperature environments.
Innovation Solution
The use of dual arm brackets with angled bracket bases and extending arms to connect and support CMC annular members to metallic annular members, employing screws or bolts through specific holes and washers to manage thermal expansion and prevent material damage, with options including clamped bent rod and strap clamp configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If CMC annular members are connected to metallic annular members using conventional bolt connections, then the structural integrity is maintained, but the differential thermal expansion causes severe connection problems and potential material damage
Solution Approach 1:
A bracket system serves as an intermediary component between the CMC annular member and the metallic annular member. The bracket is positioned to accommodate differential thermal expansion while maintaining the connection, effectively mediating the interface between the two dissimilar materials and preventing direct transmission of expansion stresses.
Solution Approach 2:
The bracket design incorporates geometric parameters and material properties that allow it to flexibly accommodate the changing dimensions of the CMC member during thermal cycling. The bracket's structural parameters are optimized to absorb expansion differences without compromising connection integrity.
2Temperature
If CMC materials are used in hot sections to withstand high temperatures, then the temperature resistance is improved, but the brittleness of CMC materials makes connections particularly problematic
Solution Approach 1:
The bracket acts as a mediator that protects the brittle CMC material from direct mechanical loading and stress concentrations at the connection interface. By positioning the bracket between the CMC member and the fastening hardware, the design isolates the CMC from tensile and shear stresses that would exploit its brittleness.
Solution Approach 2:
The connection design applies different structural qualities to different regions: the bracket provides flexible, stress-distributing support at the CMC interface, while rigid fastening hardware provides secure attachment at the metallic member interface. This localized differentiation of structural properties addresses the brittleness of CMC where it matters most.
3Reliability
If dual arm brackets are used to connect annular members with different thermal expansion coefficients, then the thermal expansion management is improved, but the device complexity increases
Solution Approach 1:
The connection system is segmented into distinct functional components: the bracket body, the arms, the fastening hardware, and the positioning features. This segmentation allows each component to be optimized for its specific function while simplifying the overall design and manufacturing process.
Solution Approach 2:
The bracket design serves multiple functions simultaneously: it accommodates thermal expansion, positions the CMC member, provides structural support, and interfaces with both CMC and metallic components. This multi-functionality reduces the need for additional specialized components, thereby managing complexity.
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 solution effectively connects and supports CMC and metallic annular members in gas turbine engines, managing thermal expansion and preventing damage to CMC materials, thereby enhancing the reliability and durability of hot section components.
Implementation Method 1
Gas turbine engine annular members having different first and second thermal expansion coefficients and connected together with dual arm brackets
Data Source
AI summary
A gas turbine engine assembly includes first and second annular members having different first and second thermal expansion coefficients connected together with dual arm V brackets. Brackets include first and second arms angularly spaced apart from a bracket centerline and extending axially away from bracket bases attached to a first one of the first and second annular members. Arms are attached to a second one of the first and second annular members. A turbine frame includes struts extending between outer and inner rings. An annular mixer and centerbody substantially made from a ceramic matrix composite materials is connected to and supported by the outer and inner rings with first and second sets respectively of the dual arm V brackets. Bracket bases of the first and second sets are attached to the outer and inner rings respectively. Arms of the first and second sets are attached to mixer and centerbody respectively.