## 2 Materials and Methods
### Bending Tests and DIC Measurements
The spot size is defined by the relationship between the resolution of the DIC camera system and the size of the sample area under inspection. These two data are used to calculate the size of the pixels in millimeters, with an optimum value of between 3 and 5 pixels. Smaller pixels are more difficult to detect during digitalization. In addition, the overlap of speckles is a critical factor since if the speckle pattern overlap is not sufficient, images may become noisy during digitalization. For this reason, it is imperative to avoid overlapping when using speckle patterns, as this can negatively affect the measurement results. The ability to identify displacements and deformations down to tenths of a millimeter with sufficient accuracy can enable the results to be used in a broader range of applications, whether in forensic, automotive, textile, or medical orthopedic applications [72]. Since light and surface reflectivity affect the camera's performance, the metallic, reflective areas were covered with masking tape to prevent interference with the measurement results. Figure 5 illustrates the experimental set-up and an appropriately painted surface that the measurement system recognizes so that it can be evaluated later. The results were then evaluated using the GOM DIC ARAMIS 2018 (GOM, Braunschweig, Germany) evaluation software. The displacement data from the GOM system were then synchronized with the mechanical load values of the load cell, which are presented in Section 3. Before starting the measurement, the camera was turned 180 degrees from its original position so that the coordinate system was also placed upside down, and the results were evaluated. The data were collected in parallel using the GOM ARAMIS (GOM, Braunschweig, Germany) camera system to measure displacement in the \(x\) direction and the HBM quantum MX840A (HBM, Darmstadt, Germany) data collector to record both force and displacement values. The ARAMIS sampling frequency was 8 Hz, and the HBM sampling frequency was 10 Hz. During the evaluation, the ARAMIS displacement values and HBM force data were evaluated during the measurements. However, due to the different sampling frequencies, the data lengths were different, so a linear interpolation of the displacement values in the \(x\) direction of the GOM measurements was necessary based on the HBM force measurement data series size (see Section 3.1). Besides the displacement measurements, the specimens were observed by GOM ATOS Triple Scan (GOM, Braunschweig, Germany) during the 28-day drying cycle to compare the stages of changes of the specimens. This differs from other technologies in that a painting process is not required in this case. Here, reference points with factory markings can be applied to the surface painted matte white. Then, by adjusting the point size and temperature (object heat) of the camera, the machine scanned the surface by rotating the rotary table. This paper used a similar method as [PERSON] et al. [73], where a non-destructive diagnostic system (GOM) was used to more accurately identify potentially deformable areas during the adaptation of automotive batteries. In both cases, the measurement process was, of course, preceded by accurate and appropriate calibration requested and recommended by the manufacturer of the instruments.