CMC Hook Attachment Region for Thermal Strain Relief
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Solution Overview
Problem
Existing ceramic matrix composite (CMC) components in gas turbine engines face challenges with thermal strain and non-uniform surfaces at attachment regions due to significant temperature gradients, leading to inaccurate positioning and potential failure of hook-mounted components.
Innovation Solution
The design incorporates a radially thinner to thicker attachment region with slots in the hooks of CMC lamina components, such as blade outer air seals, to manage thermal strain and improve positioning precision by creating uniform surfaces for mounting hooks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If CMC components are used in high temperature turbine sections, then heat resistance is improved, but thermal strain at attachment regions increases due to temperature gradients
Solution Approach 1:
The attachment region is designed with non-uniform thickness, being radially thinner at the hook end and radially thicker at the remote end. This local variation in geometry allows the attachment region to better accommodate thermal gradients, reducing thermal strain concentration at the hook attachment points while maintaining the heat resistance benefits of CMC materials in the high temperature turbine section.
2Temperature
If CMC components are used in high temperature turbine sections, then heat resistance is improved, but positioning precision of hook-mounted components deteriorates due to non-uniform surfaces
Solution Approach 1:
The attachment region features a controlled non-uniform thickness profile with a radially thinner portion at the hook end and a radially thicker portion at the remote end. This deliberate local geometric variation creates a more uniform and predictable surface geometry at the attachment interface, improving positioning precision for hook-mounted components while the overall CMC structure maintains heat resistance in the high temperature environment.
3Ease of manufacture
If uniform thickness is used in hook attachment region, then manufacturing simplicity is improved, but thermal strain concentration increases leading to potential failure
Solution Approach 1:
Rather than using uniform thickness throughout, the attachment region employs a non-uniform thickness profile with a radially thinner portion at the hook end and a radially thicker portion at the remote end. This local geometric variation is designed to distribute thermal strains more evenly throughout the attachment region, preventing strain concentration and potential failure while remaining compatible with standard CMC manufacturing processes.
4Reliability
If radially thinner attachment region is used at hook end, then thermal strain is mitigated, but structural strength may be reduced
Solution Approach 1:
The attachment region uses a non-uniform thickness profile where the radially thinner portion is located at the hook end to mitigate thermal strain, while the radially thicker portion at the remote end provides additional material to maintain structural strength. This local differentiation optimizes both thermal strain mitigation and structural integrity throughout the attachment region.
Solution Approach 2:
The solution addresses the strength-thermal strain trade-off by introducing radial thickness variation as an additional design dimension. Rather than uniformly reducing thickness to reduce strain, the thickness is strategically varied in the radial dimension, creating a gradient that mitigates thermal strain at critical locations while maintaining sufficient strength through the thicker remote portion.
Data Source
AI summary
A component for a gas turbine engine includes a component body formed of ceramic matrix composite lamina and has at least one hook. The at least one hook has an attachment region radially inward of the at least one hook. The attachment region is radially thinner from a hook end of the at least one hook to a remote end, and then becomes radially thicker. A slot is formed through a radial thickness of the at least one hook from the hook end in a remote direction, such that there are two sections of the attachment region. A gas turbine engine is also disclosed.