Functionally Graded Turbine Disk for Thermal Stress Reduction
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Solution Overview
Problem
Disk-shaped components, particularly turbine disks, face significant mechanical integrity challenges due to combined centrifugal and thermal stresses, which are exacerbated by the presence of a bore, leading to peak tensile stresses that can compromise their structural integrity, especially in materials of relatively low strength.
Innovation Solution
The use of a composite material with different thermal expansion coefficients and stress values for the center and rim portions of the disk, where the center material has a higher coefficient of thermal expansion and lower oxidation resistance, and the rim material has a lower coefficient of thermal expansion and higher oxidation resistance, is employed to mitigate thermal stresses and enhance mechanical integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a bore is introduced in the disk to pass cooling air or integrate a shaft, then the disk can be cooled or driven, but the peak tensile stress at the bore increases significantly, compromising mechanical integrity
Solution Approach 1:
The patent applies local quality by using functionally graded materials with different compositions in different regions of the disk. The material composition varies radially from the bore to the rim, with each region optimized for its specific functional requirements while maintaining overall structural integrity under combined thermal and centrifugal loads.
2Temperature
If the rim is heated by hot combustion gas, then the disk can operate in the combustion environment, but the temperature gradient generates thermal stress that combines with centrifugal stress to create peak stress at the bore
Solution Approach 1:
The patent employs parameter changes by varying the material composition and properties as a function of radial position. The functionally graded material allows continuous or stepwise changes in thermal expansion coefficient, thermal conductivity, and mechanical strength across the disk radius, enabling the structure to adapt to the temperature gradient and reduce thermal stress concentration.
3Stress or pressure
If a composite material with different thermal expansion coefficients is used at the center and rim, then thermal stress is reduced, but the manufacturing complexity increases
Solution Approach 1:
The patent utilizes composite materials with functionally graded composition to resolve the technical contradiction. By combining materials with different thermal and mechanical properties in a graded structure, the invention achieves reduced thermal stress while maintaining manufacturability through established composite fabrication techniques.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively reduces thermal stresses and improves mechanical integrity by tailoring the material properties to optimize thermal and mechanical performance across a range of operating conditions, while also offering potential for weight reduction, erosion resistance, and efficient heat transfer.
Implementation Method 1
the first material comprises a first coefficient of thermal expansion, a first stress value and a first oxidation resistance, and the second material comprises a second coefficient of thermal expansion, a second stress value and a second oxidation resistance, wherein the first coefficient of thermal expansion is greater than the second coefficient of thermal expansion
Data Source
AI summary
A process for manufacturing a disk shaped component comprising fabricating a disk shaped component using a composite material having at least a first material and a second material, wherein the first material is disposed at and proximate to a center portion of the disk shaped component and the second material is disposed at and proximate to a rim of the disk shaped component, wherein the first material comprises a first coefficient of thermal expansion, a first stress value and a first oxidation resistance, and the second material comprises a second coefficient of thermal expansion, a second stress value and a second oxidation resistance, wherein the first coefficient of thermal expansion is greater than the second coefficient of thermal expansion, the first stress value is greater than the second stress value and the first oxidation resistance is less than the second oxidation resistance.