Turbine Shroud Pin Load Distribution for CMC Wear
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Solution Overview
Problem
Gas turbine engine shrouds, particularly those in the turbine section, face challenges with high-temperature exposure and wear due to the integration of ceramic matrix composite (CMC) materials with metallic components, leading to issues with load distribution and wear resistance.
Innovation Solution
A turbine shroud assembly comprising a metallic carrier, a ceramic matrix composite blade track segment, and an attachment pin with a load-distributing protrusion that engages a variable-diameter aperture surface, distributing loads across a larger contact area to reduce wear and enhance the lifespan of the CMC components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional attachment pin is used to connect the metallic carrier and CMC blade track segment, then the assembly is simple to manufacture, but the load is concentrated on a small area causing high contact stress and wear
Solution Approach 1:
The attachment pin incorporates a load-distributing protrusion that creates a localized enlarged contact area specifically at the interface with the CMC blade track segment. This protrusion features a curved surface that matches the aperture geometry, concentrating the load distribution function at the critical wear interface while keeping the rest of the pin structure simple and straightforward to manufacture.
Solution Approach 2:
The attachment pin transitions from a simple cylindrical geometry to a three-dimensional form with a radially extending load-distributing protrusion. This adds a radial dimension to the contact interface, transforming a line contact into a surface contact and significantly increasing the contact area without substantially increasing the overall pin diameter or complexity.
2Duration of action of stationary object
If the attachment pin contacts the CMC blade track segment over a small area, then the pin structure remains simple, but wear and fretting increase reducing component lifespan
Solution Approach 1:
The load-distributing protrusion creates a localized enlarged contact area specifically where the pin interfaces with the CMC blade track segment aperture. The curved surface of the protrusion is designed to match the aperture geometry, ensuring optimal load distribution across the contact interface and minimizing wear and fretting at this critical location.
Solution Approach 2:
The attachment pin geometry is pre-configured with the load-distributing protrusion that automatically engages with the aperture surface upon assembly. This preliminary geometric design ensures that loads are distributed across a larger area from the moment of installation, preventing wear and fretting before they can cause damage, rather than requiring additional protective measures.
3Area of stationary object
If a standard cylindrical pin is used for attachment, then manufacturing is straightforward, but the contact area with the aperture surface is insufficient leading to high contact pressure
Solution Approach 1:
Rather than making the entire pin complex, the load-distributing protrusion adds the necessary contact area locally at the interface with the CMC blade track segment. The protrusion extends radially outward from the pin body and features a curved surface that matches the aperture geometry, creating an optimized contact interface without substantially increasing overall pin dimensions or manufacturing complexity.
Solution Approach 2:
The attachment pin geometry evolves from a simple cylindrical form to include a radially extending load-distributing protrusion with a curved surface. This adds a radial dimension to the contact interface, transforming a line contact into a surface contact and significantly increasing the contact area while maintaining a relatively simple manufacturing process.
Data Source
AI summary
A turbine shroud assembly includes a carrier, a blade track segment, and an attachment pin. The carrier is arranged to extend circumferentially at least partway around an axis. The blade track segment includes a runner that faces the axis to define a portion of a primary gas path of the gas turbine engine and an attachment flange that extends radially away from the runner. The attachment pin is configured to mount the blade track segment to the carrier.