Rotating Machine Crack Estimation From Surface Deformation

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Solution Overview

Problem

Existing methods for estimating hidden cracks in rotating machines, such as turbine generators, suffer from low accuracy due to the ill-posedness of the inverse problem, making it difficult to determine the size and position of cracks accurately and thus affecting the structural lifetime.

Innovation Solution

A crack estimation device and method that utilize a shape model setting unit, estimation model generation, and crack state analysis unit to estimate crack positions and sizes by probabilistic inference from surface deformation and load distribution, using matrices derived from structural analysis models.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If least square method is used to estimate hidden crack from measurement data and learning data, then the estimation process can be completed, but the accuracy of crack estimation deteriorates due to ill-posedness problem

Engineering Contradiction:
Improvecrack estimation accuracyVSAvoidestimation reliability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent replaces the conventional least square method (a direct mathematical approach) with a neural network-based computational model. The neural network learns the complex nonlinear mapping between surface deformation and hidden crack characteristics through training on simulation data, thereby achieving more accurate and reliable crack estimation while avoiding the ill-posedness issues of traditional inverse analysis methods.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the approach from using direct mathematical equations (least square method) to using learned parameters from neural network training. By training the neural network on a comprehensive dataset generated from structural analysis simulations, the system captures complex relationships between surface deformation and crack parameters, transforming the ill-posed inverse problem into a more robust parameter estimation problem.

Inventive Principle:
Principle #35Parameter changes

2Difficulty of detecting and measuring

If inverse analysis is used to estimate hidden crack from surface strain, then crack detection becomes possible, but the complexity of the analysis increases due to the ill-posedness problem

Engineering Contradiction:
Improvehidden crack detectabilityVSAvoidanalysis complexity
Core Design Contradiction:
Difficulty of detecting and measuringVSDevice complexity

Solution Approach 1:

The patent performs preliminary action by pre-training the neural network on comprehensive simulation data that covers various crack types, positions, and structural configurations. This pre-training phase creates a ready-to-use estimation model that can directly process surface deformation measurements without requiring complex real-time inverse analysis, thereby reducing operational complexity while maintaining high detectability.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent creates a computational copy of the complex inverse analysis problem by training a neural network on simulated data. Instead of directly solving the difficult inverse problem in real-time, the system uses a pre-trained neural network model that has learned the complex relationships during training, thereby simplifying the actual crack detection process while maintaining accuracy.

Inventive Principle:
Principle #26Copying

3Measurement precision

If traditional non-destructive inspection methods (ultrasonic inspection, X-ray inspection) are used, then hidden cracks can be detected, but the device size and cost increase

Engineering Contradiction:
Improvecrack detection capabilityVSAvoidinspection device size and cost
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces expensive and complex physical inspection methods (ultrasonic inspection, X-ray inspection) with a computational approach using neural networks and surface deformation measurement. This substitution eliminates the need for costly inspection equipment while achieving comparable or superior crack detection capability through intelligent algorithms that process data from simple surface sensors.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent creates a virtual copy of the inspection process by using neural network models trained on simulation data. Instead of physically penetrating or vibrating the structure to detect cracks, the system uses a computational model that learns from surface deformation patterns, thereby replacing expensive physical inspection devices with a cost-effective information processing system.

Inventive Principle:
Principle #26Copying

Data Source

PatentUS12442738B2Crack estimation device, failure diagnosis device, crack estimation method, and failure diagnosis method for rotating machine
Publication Date: 2025.10.14 MITSUBISHI ELECTRIC CORP
  • US12442738B2 patent drawing
  • US12442738B2 patent drawing
  • US12442738B2 patent drawing

AI summary

Provided are a shape model setting circuitry for setting a shape model of a target structure, a crack candidate plane in the shape model, and an observation plane of the shape model, an estimation model generator for generating an estimation model obtained from a numerical analysis of a structural analysis model by sequentially changing a boundary condition of the crack candidate plane in the structural analysis model generated from the shape model, and a crack state analyzer for estimating a position and a size of the crack by obtaining a distribution of load and displacement in the crack candidate plane at the same time by probabilistic inference through the application of an observation plane deformation vector indicating deformation of the observation plane obtained from measurement values, the estimation model, and a latent variable indicating presence or absence of the crack in the crack candidate plane.