Rotor Disk Balancing Cut Geometry to Reduce Web Stress
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Solution Overview
Problem
Existing methods for balancing integrally bladed rotor disks in gas turbine engines often result in stress concentrations due to straight cuts, which can reduce the life of the rotor disks during acceleration and deceleration.
Innovation Solution
A method involving a cutting tool that articulates along an arcuate path to create a fillet with a radius significantly larger than the axial height of the cut, reducing stress concentrations and improving balance by machining a circumferential array of blades and spacers in a unitary, one-piece structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a straight cut is machined into the annular ridge to balance the rotor disk, then the balancing operation is simple and efficient, but stress concentrations occur at the cut edges reducing rotor disk life
Solution Approach 1:
The cutting tool is articulated along an arcuate path to create a fillet with a curved surface at the cut edge, replacing the sharp corner of a straight cut. This curvature eliminates stress concentration points while maintaining material removal efficiency for balancing the rotor disk.
2Ease of manufacture
If a straight cut is made in the radial direction, then the cutting process is straightforward and quick, but the flat opposing lateral fillet creates stress concentrations during acceleration and deceleration
Solution Approach 1:
The cutting tool follows an arcuate path to generate a fillet with a curved surface having a radius of curvature significantly larger than the axial height of the cut. This curved geometry eliminates the sharp corners and flat opposing lateral fillets that cause stress concentrations, thereby improving web stress resistance during dynamic operation.
Solution Approach 2:
The geometry of the cut is changed from a straight radial cut with flat surfaces to an arcuate cut with a curved fillet surface. The radius of curvature is specifically controlled to be much larger than the axial height, fundamentally changing the stress distribution characteristics at the cut edge.
Data Source
Figure 1
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AI summary
A gas turbine engine rotor disk (60) includes a web (66) that extends inward in a radial direction from a rim (62) to a bore (68) that circumscribes an axis (X). An annular ridge (90) extends axially from the side of the web (66). A balancing cut (96) is in the annular ridge (90) that includes a fillet (98) that extends in the radial direction. Corresponding method of balancing a gas turbine engine.rotor disc (60).