CMC Airfoil Radial Core and Braided Shell
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Solution Overview
Problem
Existing CMC airfoils for turbine engines are vulnerable to mechanical distress under high stress conditions and creep rupture due to their design, failing to withstand long-term exposure to mechanical and thermal loads effectively.
Innovation Solution
A unitary CMC body comprising a core with ceramic fibers arranged radially and a shell with woven or braided ceramic fibers, where the shell's fiber density varies radially and circumferentially to enhance structural support and thermal tolerance, forming a porous ceramic preform core and shell that are infiltrated with a matrix material to create a high-strength airfoil.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If CMC airfoils are used to allow higher operating temperatures, then thermal tolerance is improved, but mechanical strength under high stress conditions deteriorates
Solution Approach 1:
The patent employs a composite structure consisting of a CMC body with a distinct core and shell. The core comprises ceramic fibers arranged in a radial direction to provide mechanical strength, while the shell comprises woven or braided ceramic fibers to provide thermal tolerance and environmental protection. This composite architecture allows the airfoil to simultaneously achieve high operating temperature capability and mechanical strength under stress.
Solution Approach 2:
The patent applies different fiber configurations to different regions of the CMC body. The core region contains radially arranged ceramic fibers optimized for mechanical loading, while the shell region contains woven or braided fibers optimized for thermal resistance and environmental protection. This local differentiation of material properties enables the structure to withstand both high temperatures and mechanical stresses effectively.
2Duration of action of moving object
If CMC bodies are subjected to extended time periods under mechanical loading, then operational duration is improved, but vulnerability to creep rupture increases
Solution Approach 1:
The composite structure with radially arranged core fibers and woven/braided shell fibers provides enhanced creep resistance. The radial fiber arrangement in the core resists centrifugal forces and mechanical loading, while the shell structure provides additional support and protection, together enabling sustained operational duration without creep rupture.
Solution Approach 2:
The CMC body is segmented into functional zones with the core and shell having distinct fiber architectures. This segmentation allows each region to specialize in resisting different types of stress, with the core handling radial mechanical loads and the shell providing circumferential support, thereby improving overall reliability under extended mechanical loading.
3Force
If shell ceramic fibers are arranged with higher surface density in radial direction, then resistance to centrifugal forces is improved, but manufacturing complexity increases
Solution Approach 1:
The patent implements a non-uniform fiber distribution in the shell, with higher surface density of radial fibers in regions experiencing greater centrifugal loading. This local quality variation optimizes mechanical performance while the use of standardized woven or braided fiber preforms keeps manufacturing complexity manageable through established textile and composite fabrication techniques.
Data Source
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AI summary
A CMC airfoil (10) and a method of manufacturing (60-64) a CMC airfoil (10) is provided, where the airfoil (10) comprises a core (12) and a shell (14). The core (12) comprises core ceramic fibers (16) extending along a span (80) of the airfoil (10). The shell (14) surrounds the core (12) and includes shell ceramic fibers (38,40). Substantially all of the core ceramic fibers (16) are arranged in a radial direction (80). The shell ceramic fibers (38,40) may be woven or braided. The braided fibers may be arranged in a braid angle (78), preferably being between 25° and 75° with respect to the radial axis (80). The core ceramic fibers (16) are preferably made of a ceramic material having a higher creep resistance than the material forming the shell ceramic fibers (38,40). Thus, the CMC airfoil (10) is able to tolerate high stress mechanical conditions.