Photoelastic Stress Analysis Using Wrapped Phase Mapping

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Solution Overview

Problem

Conventional methods for analyzing stress in objects using photoelasticity are inefficient due to complex computing algorithms and the need for extensive computing resources, as well as the requirement for specific wavelength conditions in light rays, which slows down the stress analysis process.

Innovation Solution

A method that involves analyzing spectrum data from interference fringe patterns to calculate wrapped phases, preliminary stress values, and then using a system of stress equations to determine an estimated stress value, without the need for specific wavelength conditions and with reduced computational complexity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If spatial phase unwrapping algorithm or temporal phase unwrapping algorithm is used to convert wrapped phases into unwrapped phases, then stress analysis can be performed, but computing resources and time are excessively consumed

Engineering Contradiction:

Improvestress analysis accuracyVSAvoidcomputing time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent extracts the essential relationship between wrapped phases and stress values, eliminating the need for complex phase unwrapping operations. By directly establishing a mapping between wrapped phases and stress values through calibration, the method removes the computationally intensive modulo operations while preserving the core measurement capability.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent performs preliminary calibration to establish the relationship between wrapped phases and stress values before actual stress analysis. This pre-computed mapping table allows direct lookup of stress values from wrapped phases without requiring real-time phase unwrapping, significantly reducing computing time during measurement.

Inventive Principle:

Principle #10Preliminary action

2Measurement precision

If iterative method is used to compare spectrum data with pre-stored database, then stress analysis can be performed, but considerable amount of time is required reducing overall efficiency

Engineering Contradiction:

Improvestress analysis accuracyVSAvoidoverall efficiency

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent creates a simplified computational model that copies only the essential relationship between wrapped phases and stress values, eliminating the need for complex iterative comparisons with large databases. The calibrated mapping table serves as a lightweight copy that preserves measurement accuracy while dramatically improving processing speed.

Inventive Principle:

Principle #26Copying

3Measurement precision

If light rays with different wavelengths satisfying specific condition are used in photoelasticity, then spectrum data can be obtained, but the wavelength constraint increases system complexity

Engineering Contradiction:

Improvespectrum data qualityVSAvoidwavelength selection complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent makes the stress analysis method universal by showing that it works with any set of three wavelengths, eliminating the need for specific wavelength conditions. The calibration process adapts to whatever wavelengths are available, making the system versatile and eliminating complex wavelength selection requirements.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent changes the approach from requiring fixed wavelength parameters to accepting variable wavelengths. By performing calibration with the actual wavelengths used, the system adapts to different wavelength combinations without requiring them to satisfy specific mathematical conditions, thereby reducing device complexity.

Inventive Principle:

Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This method significantly reduces the computational time and resources required for stress analysis, improving efficiency by eliminating the need for complex algorithms and specific wavelength conditions, while enhancing the accuracy of stress value calculations.

Implementation Method 1

The spectrum data is obtained from an interference fringe pattern of the object that results from performing photoelasticity

Methodology Applied

Scientific EffectPhotoelasticity: Photoelasticity

Implementation Method 2

The spectrum data is obtained from an interference fringe pattern of the object that results from performing photoelasticity

Methodology Applied

Scientific EffectInterference: Interference

Data Source

PatentUS10036677B2Method for analyzing stress in an object

Publication Date: 2018.07.31 NATIONAL TSING HUA UNIVERSITY

AI summary

A method for analyzing stress in an object according to spectrum data is provided. The spectrum data is obtained from an interference fringe pattern of the object that results from performing photoelasticity. The method includes: analyzing the spectrum data to obtain three sets of intensity data related respectively to different wavelengths of light used in photoelasticity; calculating wrapped phases according to the three sets of intensity data, respectively; calculating preliminary stress values according to the wrapped phases, respectively; determining a system of stress equations according to a relation among the preliminary stress values; and calculating an estimated stress value using the system of stress equations.