Residual Stress Estimation via Spline Interpolation

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Solution Overview

Problem

The estimation precision of residual stress in structures is heavily influenced by the set analysis range, and conventionally, users rely on trial and error based on experience to determine this range, often leading to inappropriate settings.

Innovation Solution

A method and device that acquire the position and size of the analysis range, divide it into regions, and use piecewise distribution functions with spline interpolation to estimate inherent strain distribution, allowing for accurate residual stress calculation without relying on user experience.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If users set the analysis range through trial and error based on experience, then the analysis range may be appropriately determined in some cases, but the estimation precision of residual stress cannot be ensured when the analysis range is incorrectly set

Engineering Contradiction:
Improveestimation precision of residual stressVSAvoiddifficulty in setting analysis range
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

The system automatically determines the analysis range by itself without requiring user experience or trial-and-error adjustments. The control device acquires conditions concerning the analysis range autonomously and uses this information to estimate inherent strain distribution, making the system self-sufficient in determining optimal parameters.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The control device performs preliminary acquisition of conditions concerning the analysis range (such as position and size) before conducting the residual stress estimation. This preliminary action ensures that the analysis range is properly configured in advance, preventing estimation errors that would otherwise require iterative adjustments.

Inventive Principle:
Principle #10Preliminary action

2Measurement precision

If a single distribution function is used to approximate inherent strain distribution, then the calculation process is simple, but the estimation precision decreases when the inherent strain distribution is complex

Engineering Contradiction:
Improveprecision of inherent strain distribution estimationVSAvoidcomplexity of distribution function
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The analysis range is divided into multiple divided regions, and a separate distribution function is defined for each region. This segmentation allows the system to accurately capture complex inherent strain distributions in different areas while maintaining manageable complexity within each individual region.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different distribution functions with appropriate characteristics are assigned to different divided regions based on the local inherent strain distribution characteristics. This local quality approach ensures that each region is modeled with the most suitable function, improving overall estimation precision without unnecessarily complicating the entire system.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP3267167B1Residual stress estimation method and residual stress estimation device
Publication Date: 2020.02.19 KOBE STEEL LTD
  • EP3267167B1 patent drawingFigure 1
  • EP3267167B1 patent drawingFigure 2~3
  • EP3267167B1 patent drawingFigure 4

AI summary

Provided is a residual stress estimation method and a residual stress estimation device which are capable of setting an appropriate analysis range without depending on a user's experience. The residual stress estimation device displays analysis results in which strain generated in a structure is analyzed. A user determines a position and a size of an analysis range based on the analysis results, and inputs the determined position and size of the analysis range and a measured value of residual stress of a cut piece of the structure at a measurement point to the residual stress estimation device. The residual stress estimation device estimates distribution of inherent strain in the analysis range to approximate the inherent strain distribution obtained from the input measured value of the residual stress of the cut piece, thereby estimating the residual stress of the structure based on the inherent strain.