CMC Gas Turbine Blade Platform Capture Feature
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Solution Overview
Problem
Gas turbine engine blades made from ceramic matrix composites (CMCs) face challenges with the interlaminar bond between the platform and transition portions being relatively weak, which can lead to potential failure under centrifugal forces during operation.
Innovation Solution
Incorporating a capture feature, such as a capture ring or pins, to provide additional mechanical restraint to the platform portion, and orienting fibers in the CMC to enhance strength in the radial direction, along with using a CMC or metal platform that is co-processed with the airfoil and dovetail portions to form a unitary blade.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the platform portion is attached to the transition portion using only an interlaminar bond from CMC matrix material, then the blade structure remains simple and manufacturing is easier, but the bond strength is relatively weak and may fail under centrifugal forces
Solution Approach 1:
The platform portion is divided into multiple segments or sections that can be independently positioned and restrained. Capture features are distributed at multiple locations around the periphery of the platform portion, allowing the structure to be segmented into functional zones (restrained areas and unrestrained areas) that work together to prevent platform movement while maintaining manufacturing feasibility
Solution Approach 2:
Capture features are pre-formed as integral parts of the airfoil portion during the CMC fabrication process, before the platform portion is attached. These capture features include pre-positioned recesses, grooves, or protrusions that are prepared in advance to mechanically restrain the platform portion, eliminating the need for additional strengthening measures after assembly
2Reliability
If capture features are added to mechanically restrain the platform portion, then the likelihood of platform movement is reduced, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The capture features are merged with the airfoil portion structure, forming an integrated design where the capture features are created as part of the same CMC fabrication process. This combining of functions (structural airfoil with integrated restraint features) eliminates separate manufacturing steps and reduces overall complexity despite adding restraint functionality
Solution Approach 2:
The CMC fabrication process itself is used to create the capture features within the airfoil portion, allowing the material and process to serve multiple purposes. The same infiltrated matrix material that provides structural integrity to the airfoil also forms the capture features, and the same manufacturing steps that shape the airfoil also create the restraint geometry
Data Source
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AI summary
The disclosure describes a gas turbine engine blade that includes a dovetail portion comprising a first ceramic matrix composite, an airfoil portion comprising the first ceramic matrix composite, a transition portion between the airfoil portion and the dovetail portion, and a platform portion that substantially surrounds the transition portion. The airfoil portion may define a capture feature that is configured to engage with and mechanically restrain the platform portion from moving beyond the capture feature toward a tip of the airfoil portion.