Stress Distribution Analysis for Surface Shape Defect Estimation

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Solution Overview

Problem

Current methods fail to quantitatively estimate generating regions or source regions of surface shape defects like wrinkles and surface deflection during deformation processing, particularly in press forming, roll forming, and hydroforming, limiting the ability to predict and prevent these defects effectively.

Innovation Solution

A method using finite element analysis to obtain and compare stress distributions at different processing points, dividing the stress distribution into regions to identify areas with significant stress differences, and evaluating these regions for surface shape defect generation using indices such as minimum or maximum stress values or gradients.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If the strength of the steel sheet is increased to reduce weight, then weight reduction is achieved, but manufacturing precision deteriorates due to spring back and wrinkles

Engineering Contradiction:
Improveweight of vehicle membersVSAvoidshape accuracy of press-formed members
Core Design Contradiction:
Weight of moving objectVSManufacturing precision

Solution Approach 1:

The invention performs preliminary estimation of spring back and wrinkle generating regions through finite element analysis before actual press forming. By calculating stress distributions at multiple time points and identifying critical regions in advance, the method enables proactive design modifications to prevent defects, thereby maintaining manufacturing precision while using high-strength steel for weight reduction

Inventive Principle:
Principle #10Preliminary action

2Adaptability or versatility

If design changes are made at the design stage, then adaptability is improved, but productivity deteriorates due to repeated investigation of forming methods

Engineering Contradiction:
Improvedesign flexibilityVSAvoiddevelopment process efficiency
Core Design Contradiction:
Adaptability or versatilityVSProductivity

Solution Approach 1:

The invention performs preliminary estimation of surface shape defects at the design stage using finite element analysis. By predicting spring back and wrinkle generating regions before actual forming, the method enables design validation and optimization early in the development process, reducing the need for repeated forming investigations when design changes are made, thus improving productivity while maintaining design flexibility

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The invention creates a virtual model of the press forming process using finite element analysis to simulate stress distributions and predict defect regions. This digital copy allows for repeated design iterations and evaluations without physical prototyping, enabling adaptability to design changes while maintaining productivity by eliminating the need for repeated physical forming investigations

Inventive Principle:
Principle #26Copying

Data Source

PatentEP3736059A1Method for estimating surface shape defect generating regions, method for estimating surface shape defect source regions, surface shape defect generating region estimating device, shape defect source region estimating device, program and recording media
Publication Date: 2020.11.11 NIPPON STEEL CORPORATION
  • EP3736059A1 patent drawingFigure 1
  • EP3736059A1 patent drawingFigure 2
  • EP3736059A1 patent drawingFigure 3~4

AI summary

There is provided a surface shape defect generating region estimating method for estimating a generating region of a surface shape defect of a deformation-processed product obtained by performing deformation processing with respect to a workpiece, the method including: a first stress distribution obtaining process of obtaining first stress distribution σ(T1); a second stress distribution obtaining process of obtaining a second stress distribution σ(T2); a comparative stress distribution obtaining process of obtaining comparative stress distribution σ(T1,T2); a division comparative stress distribution obtaining process of obtaining division comparative stress distribution σDIV(T1,T2); and a surface shape defect generating region estimating process of estimating whether or not each of the divided regions DK is a generating region of the surface shape defect.