Random Dot Pattern for Deformation Measurement
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Solution Overview
Problem
Existing methods for measuring full-field deformation of irregularly shaped bodies are prone to errors due to the difficulty in applying uniform grids and the sensitivity of digital image correlation methods to speckle pattern characteristics, requiring specialized setups and conditions.
Innovation Solution
A computer-implemented method for measuring full-field deformation characteristics by applying a dot pattern on a deformable body, acquiring images before and after deformation, identifying characteristic points, eliminating irregular objects, and calculating displacement and strain vectors using mesh-free approximation techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pure grid methods are used for measuring deformation, then full-field measurements can be obtained, but the difficulty of applying uniform grids to irregularly shaped bodies introduces measurement errors
Solution Approach 1:
The patent applies a random dot pattern rather than a uniform grid, allowing the measurement method to accommodate irregularly shaped bodies without requiring precise grid application. The random distribution of dots provides sufficient measurement points while being easily applicable to any specimen geometry.
Solution Approach 2:
The patent uses a random dot pattern where dots are distributed non-uniformly across the specimen surface. This allows different regions to have different dot densities according to local requirements, making the method adaptable to irregular shapes while maintaining measurement accuracy through local characteristic point identification.
2Measurement precision
If digital image correlation methods with speckle patterns are used, then full-field measurements are possible, but the method is highly sensitive to speckle pattern characteristics requiring specialized setups
Solution Approach 1:
The patent extracts the essential measurement function from complex digital image correlation methods by using simple characteristic point identification and matching. This eliminates the need for specialized speckle pattern application and complex correlation algorithms, reducing setup requirements while maintaining measurement capability.
Solution Approach 2:
The patent replaces expensive and complex specialized setups with a simple random dot pattern that can be easily applied using basic materials. The dots serve as temporary markers that are easily applied and removed, eliminating the need for permanent speckle pattern application equipment.
3Measurement precision
If uniform grids are applied to irregularly shaped bodies, then deformation measurement is possible, but inaccuracies in grid application become a major source of errors
Solution Approach 1:
The patent replaces the symmetric uniform grid with an asymmetric random dot pattern. This allows the measurement method to adapt to irregular specimen shapes without requiring precise geometric alignment, thereby eliminating grid application errors while maintaining reliable deformation measurement through characteristic point tracking.
Data Source
AI summary
A computer-implemented method for measuring full field deformation characteristics of a deformable body. The method includes determining optical setup design parameters for measuring displacement and strain fields, and generating and applying a dot pattern on a planar side of a deformable body. A sequence of images of the dot pattern is acquired before and after deformation of the body. Irregular objects are eliminated from the images based on dot light intensity threshold and the object area or another geometrical cutoff criterion. The characteristic points of the dots are determined, and the characteristic points are matched between two or more of the sequential images. The displacement vector of the characteristic points is found, and mesh free or other techniques are used to estimate the full field displacement based on the displacement vector of the characteristic points. Strain tensor or other displacement-derived quantities can also be estimated using mesh-free or other analysis techniques.