CMC Nozzle Airfoil Joint Geometry for Shear-Resistant Bonding
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Solution Overview
Problem
Existing gas turbine engines face challenges in joining CMC nozzle segments with airfoil segments to withstand shear forces without using bulky mechanical structures or separate fasteners, which can affect aerodynamics and increase costs.
Innovation Solution
The airfoil segments are bonded to end bands using a monolithic CMC component design with extensions and dovetail-shaped slots to increase the total interface surface area, allowing the joint to accommodate shear forces effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If mechanical structures or separate fasteners are used to join CMC nozzle segments with airfoil segments, then the joint can withstand shear forces, but the aerodynamic performance deteriorates and device complexity increases
Solution Approach 1:
The patent merges the joining function directly into the monolithic CMC component structure itself, eliminating separate fasteners or mechanical attachment structures. The extensions and dovetail-shaped slots are integrated features of the CMC component that provide both structural integrity and shear force resistance without requiring additional mechanical elements.
Solution Approach 2:
The patent replaces traditional mechanical fastening systems with a chemical bonding approach using a bonding agent applied to the interface surfaces. The bonding agent creates a chemical bond between the CMC component and the airfoil segment, substituting mechanical fasteners with a chemical joining mechanism that maintains aerodynamic smoothness.
2Strength
If extensions and dovetail-shaped slots are used to increase interface surface area, then the joint can accommodate shear forces effectively, but manufacturing complexity increases
Solution Approach 1:
The patent utilizes the composite nature of CMC materials to create extensions and dovetail-shaped slots that are inherently part of the material structure. The ceramic matrix composite allows for complex geometries to be formed during the manufacturing process itself, integrating the joining features into the material fabrication rather than requiring separate machining or assembly steps.
3Device complexity
If a monolithic CMC component design is used without bulky mechanical structures, then aerodynamic performance is maintained, but the joint may insufficiently withstand shear forces
Solution Approach 1:
The patent adds dimensional complexity through extensions that protrude from the CMC component surface and dovetail-shaped slots that create multi-faceted interface geometries. These extensions into additional spatial dimensions increase the total interface surface area available for bonding, thereby increasing shear force resistance without adding bulky external mechanical structures that would disrupt aerodynamics.
Data Source
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AI summary
A gas turbine engine is provided. The gas turbine engine includes a stage of airfoil segments having a first ceramic matrix composite (CMC) airfoil segment, the first CMC airfoil segment includes: an end band having a radial surface defining a cold side surface area, ACS; and an airfoil coupled to or formed with the end band, the airfoil and the end band defining a joint therebetween, the joint including one or more radial interfaces defining a total radial interface surface area, ARI, and one or more axial interfaces defining a total axial interface surface area, AAI. The first CMC airfoil segment defines a first ratio of the cold side surface area, ACS, to the total axial interface surface area, AAI, and a second ratio of the total axial interface surface area, AAI to the total radial interface surface area, ARI.