Strain Estimation via Pressure Signal Conversion

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Solution Overview

Problem

It is challenging to directly attach strain gauges to components like inducer blades in turbo pumps during flight or use, necessitating a method to estimate strain without using a strain gauge for real-time evaluation of component lifetime under stress.

Innovation Solution

A strain estimation device that acquires a pressure signal near the component and converts it into a strain signal using an estimation filter based on the power spectral density of pressure and strain, allowing for strain estimation without a strain gauge.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a strain gauge is attached to a component during flight or use, then real-time strain measurement is achieved, but the difficulty of attachment and processing requirements increase significantly

Engineering Contradiction:
Improvestrain measurementVSAvoidstrain gauge attachment difficulty
Core Design Contradiction:
Measurement precisionVSDifficulty of detecting and measuring

Solution Approach 1:

The patent uses pressure as an intermediary parameter to indirectly measure strain. Instead of directly attaching a strain gauge to the component, a pressure sensor measures pressure changes in the fluid, which are then converted to strain values through a transfer function. This intermediary approach avoids the attachment difficulties while maintaining measurement capability.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the mechanical strain gauge system with a pressure-based measurement system. By substituting the direct mechanical contact method (strain gauge) with a fluid pressure measurement method, the system eliminates the need for physical attachment to the component surface while still achieving strain estimation.

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

2Measurement precision

If a strain gauge is attached to a component, then strain data can be acquired, but additional processing steps are required

Engineering Contradiction:
Improvestrain measurementVSAvoidprocessing requirements
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The pressure field serves as an intermediary that naturally transmits strain information without requiring complex signal processing. The pressure changes in the fluid directly reflect the component's strain state, and the transfer function provides a straightforward conversion mechanism, reducing processing complexity compared to strain gauge signal conditioning.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If real-time strain evaluation is performed using conventional methods, then component lifetime can be assessed, but the system becomes complex and requires direct component access

Engineering Contradiction:
Improvecomponent lifetime evaluationVSAvoidsystem complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The pressure sensor serves multiple functions: it measures pressure changes in the fluid and simultaneously provides the data needed for strain estimation and lifetime evaluation. This multi-functionality reduces system complexity by eliminating the need for separate strain measurement equipment while maintaining reliability in component lifetime assessment.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP3467461B1Strain estimation device, diagnosis device, and strain estimation method
Publication Date: 2021.10.20 IHI CORP
  • EP3467461B1 patent drawingFigure 1
  • EP3467461B1 patent drawingFigure 2
  • EP3467461B1 patent drawingFigure 3

AI summary

A strain estimation device according to an aspect of the present disclosure is a strain estimation device that estimates strain of a component provided in a fluid and includes a pressure acquisition unit that acquires a pressure signal including time-series pressure values at a predetermined position in a vicinity of the component, an estimation unit that estimates, based on the pressure signal, a strain signal including time-series strain values occurring at the component, and an output unit that outputs the strain signal. The estimation unit converts the pressure signal into the strain signal using an estimation filter determined based on a power spectral density of pressure and a power spectral density of strain occurring at the component when the pressure is applied to the position.