CMC Shroud Support System Load Spreading Design
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Solution Overview
Problem
Ceramic matrix composite (CMC) shroud segments in gas turbine engines face challenges due to low tensile ductility and mismatched thermal expansion coefficients with metal alloys, leading to stress concentrations and potential failure under high temperature and pressure conditions.
Innovation Solution
A shroud support system with load spreading and redundant couplings, featuring a CMC shroud hanger with a retainer and baffle design that reduces stress concentrations and improves bolt durability, utilizing a tapered gusset and abradable materials to distribute loads and enhance structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If CMC materials are used for shroud segments to operate at higher temperatures, then temperature capability is improved, but stress concentration and failure risk increase due to low tensile ductility and mismatched thermal expansion coefficients
Solution Approach 1:
The patent applies parameter changes by modifying the geometric parameters of the shroud segment design, specifically incorporating radius of curvature requirements (R1 ≥ 0.050 inches, R2 ≥ 0.025 inches) at transition zones. This geometric parameter optimization reduces stress concentration factors while maintaining the high-temperature capability of CMC materials, thereby improving reliability without sacrificing temperature performance.
2Device complexity
If a single bolted connection is used to couple shrouds to the hanger, then device complexity is reduced, but reliability decreases due to potential crack or bolt failure leading to disconnection
Solution Approach 1:
The patent applies segmentation by dividing the single bolted connection into multiple discrete bolted connections distributed around the shroud-hanger interface. This segmentation provides redundancy, ensuring that if one bolt or connection point fails, the remaining connections maintain the structural integrity and prevent disconnection, thereby improving reliability while maintaining relatively simple device complexity.
3Ease of operation
If CMC shroud segments are restrained and cooled on one surface during operation, then operational control is improved, but stress concentrations develop leading to segment failure
Solution Approach 1:
The patent applies parameter changes by optimizing the geometric parameters of the shroud segment, specifically the radius of curvature at transition zones (R1 ≥ 0.050 inches, R2 ≥ 0.025 inches). These geometric modifications reduce stress concentration factors that would otherwise develop during restrained cooling operations, allowing operational control to be maintained while preserving segment strength and preventing failure.
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 solution effectively enhances the reliability and durability of CMC shroud support systems by reducing stress concentrations and improving bolt durability, thereby extending the design life and operational efficiency of gas turbine components.
Implementation Method 1
an abradable material 43 may be positioned on the lowermost surface of the CMC shroud segment 41
Implementation Method 2
A shroud support system with load spreading and redundant couplings, featuring a CMC shroud hanger with a retainer and baffle design that reduces stress concentrations and improves bolt durability, utilizing a tapered gusset and abradable materials to distribute loads
Data Source
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AI summary
A shroud support system 30 with load spreading comprises a shroud hanger 70 having a first wall 72 and a second wall 74 spaced apart in an axial direction by a retainer support wall 76, a ceramic matrix composite shroud segment 41 disposed in the shroud hanger between the first and second walls and the retainer support wall, a retainer 80 having circumferentially spaced first and second bolt holes 71, the retainer passing through the shroud, first and second bolts 79 passing through the shroud hanger and engaging the first and second bolt holes of the retainer.