Integrally Bladed Rotor Repair Using Mistuning Vibration Modeling
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Solution Overview
Problem
Integrally bladed rotors (IBRs) in gas turbine engines face unique vibrational challenges due to mistuning, where manufacturing tolerances and damage lead to varying blade frequencies, increasing the risk of high cycle fatigue and mechanical failure, and existing repair methods like blending can exacerbate these issues by altering vibrational characteristics.
Innovation Solution
The use of reduced order modeling, specifically the Fundamental Mistuning Model (FMM), to simulate and predict the vibrational response of IBRs, allowing for automated maintenance and repair by measuring blade shapes and predicting changes in inherent vibratory properties, enabling more precise and safe repair techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If blending repair is performed on damaged blades, then the blade surface is restored and structural integrity is improved, but the vibrational characteristics change and may cause unanticipated vibrations
Solution Approach 1:
The system performs preliminary vibration analysis and modeling before actual repair to predict how blending will affect vibrational characteristics. This allows planners to anticipate potential issues and adjust repair parameters beforehand, preventing unanticipated vibrations while maintaining structural integrity
Solution Approach 2:
The system uses measured vibration data from the IBR to update the reduced order model, creating a feedback loop that refines predictions of how blending will affect vibrational behavior. This iterative process allows for more accurate prediction and control of post-repair vibrational characteristics
2Reliability
If conservative blend limits are established for all IBRs, then unanticipated vibrations are prevented, but repair flexibility is reduced and sustainment costs increase
Solution Approach 1:
The system transitions from applying universal conservative blend limits to determining blade-specific repair allowances based on individual IBR vibrational characteristics. Each IBR receives customized repair guidelines tailored to its specific mistuning pattern and vibrational behavior, optimizing both safety and repair flexibility
Solution Approach 2:
The system uses reduced order modeling to calculate specific blend allowance parameters for each IBR based on its vibrational properties. These parameterized allowances replace conservative fixed limits, enabling optimized repair decisions that balance vibration prevention with cost-effective sustainment
3Measurement precision
If reduced order modeling is used to predict vibrational changes, then repair accuracy is improved and unanticipated vibrations are reduced, but computational complexity increases
Solution Approach 1:
The system creates a simplified mathematical copy (reduced order model) that replicates the essential vibrational behavior of the complex IBR system. This model captures the dominant vibrational characteristics without requiring full-fidelity computational resources, enabling accurate predictions with reduced complexity
Solution Approach 2:
The reduced order model uses a limited set of key parameters (mode shapes, natural frequencies, mistuning values) to represent the complex vibrational behavior. By focusing on these critical parameters rather than full system complexity, the model achieves accurate predictions with computational efficiency
Data Source
AI summary
A method and apparatus for maintaining integrally bladed rotors (IBR) includes using first vibration data from a IBR vibration apparatus of a first IBR to determine a set of values for a corresponding set of inherent vibratory properties based on a reduced order model for an IBR type to which the first IBR belongs. Shape data indicating an initial shape of a surface of a first blade is used, with repair data that indicates a candidate repair to form a restored shape, to determine a change in a value of an inherent blade section vibratory property of the set of inherent vibratory properties. A condition of the first IBR is determined based at least in part on the change in the value of the inherent blade section vibratory property. The first IBR is maintained based on the condition.