Three-dimensional coordinate subset correlation method based on tangent-plane constrained gradients for...

Area of Science:

• Solid Mechanics
• Experimental Mechanics
• Optical Measurement Techniques

Background:

• Conventional three-dimensional digital image correlation (3D-DIC) relies on image-domain correlation, which struggles with complex geometries and large deformations due to perspective effects.
• This limitation leads to shape-function mismatch and measurement artifacts in traditional 3D-DIC methods.

Purpose of the Study:

• To extend three-dimensional coordinate subset correlation (3D-CSC) for stereo-DIC-based deformation measurement.
• To establish direct correspondence in 3D physical space between reference and deformed object surfaces.
• To enhance measurement accuracy and suppress projection-induced artifacts in deformation analysis.

Main Methods:

• Developed a novel three-dimensional coordinate subset correlation (3D-CSC) approach operating directly in 3D physical space.
• Implemented a tangent-plane-constrained surface-gradient reconstruction strategy for accurate surface analysis.
• Utilized a 3D physical-space inverse compositional Gauss-Newton formulation for efficient nonlinear optimization, preserving the constant-Hessian property.

Main Results:

• The proposed 3D-CSC method demonstrated improved accuracy in displacement and strain measurements compared to conventional 3D-DIC.
• Effectively suppressed deformation artifacts arising from projection effects, particularly under complex surface geometries.
• Validated through numerical simulations and experimental testing, confirming its robustness and reliability.

Conclusions:

• The developed 3D-CSC method offers a more robust and accurate solution for stereo-DIC-based deformation measurement.
• This technique overcomes the limitations of image-domain correlation, providing superior performance for complex scenarios.
• It represents a significant advancement in optical measurement techniques for solid mechanics applications.