Stress Estimation Using Digital Image Correlation with Compensation of Camera Motion-Induced Error.

Area of Science:

• Structural Engineering
• Materials Science
• Non-Destructive Testing

Background:

• Residual stress measurement is crucial for assessing the health of in-service structures.
• The stress relaxation method (SRM) combined with digital image correlation (DIC) is a promising technique for stress estimation.
• Existing SRM/DIC methods face challenges with camera vibration and low pixel density due to camera distance during hole drilling.

Purpose of the Study:

• To propose a novel SRM/DIC-based stress estimation method.
• To overcome practical limitations of current SRM/DIC techniques, specifically camera motion and low resolution.
• To enable accurate stress measurement even with minor structural damage.

Main Methods:

• Developed an SRM/DIC method allowing camera removal and relocation during hole drilling.
• Utilized close-proximity imaging for high pixel density and detection of subtle displacements.
• Formulated a mathematical approach to correct for false displacement fields caused by camera relocation.

Main Results:

• The proposed method successfully acquires high-resolution displacement data.
• Mathematical formulation effectively removes relocation-induced errors in DIC results.
• Numerical and experimental validations confirm the method's efficacy.

Conclusions:

• The novel SRM/DIC method enhances accuracy and practicality for in-service structural stress measurement.
• This technique allows for precise analysis of residual stresses with improved imaging capabilities.
• The study provides a robust solution for overcoming limitations in conventional stress measurement methods.