Method for luminescent digital image correlation deformation measurement in non-illuminated environments

This study presents a luminescent digital image correlation (DIC) method that utilizes long afterglow materials to prepare speckle patterns, overcoming the limitations of classical DIC in achieving high-precision deformation measurements, such as the issues of specular reflections from specimens and insufficient contrast of speckle patterns. While fluorescent DIC has some advantages in overcoming these limitations, it relies on active ultraviolet light sources, making it challenging for luminescent measurements. Long afterglow materials, capable of maintaining brightness for extended periods, serve as a viable alternative. Through sphere reconstruction experiments, the accuracy of this method was validated, demonstrating a relative error of 0.04% under well-illuminated conditions and 0.025% under non-illuminated conditions. Finite element simulations and a comparison with DIC experimental results showcased excellent consistency, suggesting the potential for this method to further replace fluorescent DIC measurements. Furthermore, the study revealed that speckle patterns prepared using this approach ensure measurement validity in both well-illuminated and non-illuminated scenarios. This luminescent DIC method holds promising potential for broader applications in non-illuminated measurement environments.