Assessment of the Film-Free Water Decal Method for Speckle Pattern Application in Digital Image Correlation

Abstract

Digital Image Correlation (DIC) often encounters challenges with variability and consistency in traditional speckle pattern application techniques, such as spray-painting, affecting measurement accuracy and reliability. This study evaluates a film-free water decal method as an alternative for applying speckle patterns in DIC. SS275 structural steel specimens were prepared with speckle patterns using both the film-free water decal method and traditional spray-painting. The quality of the speckle patterns was assessed, and their effectiveness for DIC was evaluated through tensile testing and a comparison with strain gauge measurements. The film-free water decal method provided enhanced control over speckle pattern application, resulting in high-quality, consistent patterns. Strain measurements obtained using this method closely matched those from traditional methods, confirming its reliability. The film-free water decal method offers a practical and reliable alternative to spray-painting, improving the consistency and accuracy of DIC experiments, with potential applications in various engineering and scientific fields.

Keywords

• film-free water decal
• digital image correlation (DIC)
• speckle pattern
• SS275 steel
• strain measurement
• tensile testing