Integrally Bladed Rotor Repair Using Vibration-Based Blend Limits
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Solution Overview
Problem
Integrally bladed rotors (IBRs) in gas turbine engines face challenges due to mistuning and damage from foreign objects, leading to unpredictable vibrations and increased risk of high cycle fatigue damage.
Innovation Solution
The use of reduced order modeling, specifically the Fundamental Mistuning Model (FMM), to characterize the dynamic response of IBRs independently of environmental conditions, allowing for simulation of repair effects and prediction of vibratory properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of repair
If blending is used to repair damaged IBR blades, then the blade surface is smoothed and structural integrity is restored, but the vibrational characteristics of the IBR change unpredictably, potentially causing excessive vibrations and expanding damage
Solution Approach 1:
The patent applies preliminary action by performing virtual blending simulations before actual physical blending. The system uses finite element models to predict how different blend depths and configurations will affect blade vibrational characteristics, allowing operators to select repair parameters that will not cause excessive vibrations or instability before committing to the actual repair operation.
Solution Approach 2:
The patent implements feedback by measuring the actual vibrational characteristics of the IBR before and after blending repairs, then using this data to update and refine the finite element models. This closed-loop feedback system allows the model to become increasingly accurate in predicting vibrational behavior, enabling better repair decisions and reducing the risk of causing excessive vibrations through blending operations.
2Reliability
If conservative blend limits are established for all IBRs of a particular design, then unpredictable vibrations and expanding damage are prevented, but repair flexibility is reduced and sustainment costs increase
Solution Approach 1:
The patent applies local quality by transitioning from uniform conservative blend limits applied to all IBRs of a design to individualized blend limits specific to each IBR's actual vibrational characteristics. The system measures and models the unique mistuning and vibrational behavior of each rotor, then determines appropriate blend limits tailored to that specific IBR, allowing more aggressive and flexible repairs where the structure can tolerate it while maintaining safety where it cannot.
Solution Approach 2:
The patent implements parameter changes by using measured vibrational data and finite element modeling to dynamically determine blend limit parameters for each specific IBR rather than using fixed conservative limits. The system calculates maximum allowable blend depths and configurations based on the actual mistuning values and vibrational characteristics of each rotor, enabling optimized repair parameters that balance safety with repair flexibility and cost-effectiveness.
3Ease of repair
If extensive blending is performed on damaged IBR blades, then more severe damage can be repaired, but the risk of causing excessive vibrations and expanding damage increases
Solution Approach 1:
The patent applies preliminary action by performing virtual blending simulations using finite element models to predict the vibrational consequences of different blend depths and configurations before actual repairs are performed. This allows operators to determine the maximum allowable blend depth that will repair the damage while keeping vibrations within acceptable limits, enabling more aggressive and effective repairs without risking excessive vibrations.
4Ease of manufacture
If individualized blend limits are determined for each IBR based on measured characteristics, then repair flexibility and cost-effectiveness are improved, but measurement and analysis complexity increases
Solution Approach 1:
The patent applies mechanics substitution by replacing complex manual measurement and analysis procedures with automated systems. The system uses automated vibration measurement equipment to capture IBR vibrational characteristics and employs finite element modeling software to automatically process the data, calculate mistuning values, and determine individualized blend limits. This automation reduces the complexity burden on operators while enabling sophisticated individualized repair optimization.
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.