# A Novel Low-Cost DIC-Based Residual Stress Measurement Device
## 2 Device Design
This involves completely covering the sample with a thin layer of white paint. Once the white paint completely dies, black paint is used to mark the speckle patterns, aimed to cover 50% of the measurement area. This process takes 45 min, which is significantly quicker than the installation of a strain gauge for residual stress measurement. It should be noted that, as is the case for all DIC measurements, the precision of the displacement field estimates is highly dependent upon the quality of the pattern contrast and density. This has been the focus of numerous previous studies [58; 59] and the good practice guidance outlined in these studies was followed to refine the patterns used in this study. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**No.** & **Subsystem** & **Quantity** & **Part Name** & **Cost Per Piece (\(\ell\))** & **Total Cost (\(\ell\))** \\ \hline \multirow{2}{*}{1} & \multirow{2}{*}{DIC System} & \multirow{2}{*}{1} & HAYEAR 48 MP Microscope Camera + 100\(\times\) C-mount & & \\  & & & Lens + 56 LED Ring Light For Soldering Repair + & 108.55 & 108.55 \\ \hline \multirow{2}{*}{2} & \multirow{2}{*}{Drilling System} & \multirow{2}{*}{1} & TACKLIFE Rotary Tool Kit & 35.99 & 35.99 \\ \cline{3-5}  & & & 1 & 1.6 mm Tungsten Carbide PCB Drill Bit & 8.59 & 8.59 \\ \hline \multirow{2}{*}{4} & \multirow{2}{*}{Speckle Pattern Application} & \multirow{2}{*}{1} & Plasti-kote 3101 400 mL Super Spray Paint-Matt Black & 5.02 & 5.02 \\ \cline{3-5}  & & & Plasti-kote 3100 SE 400 mL Super Matt Spray & & 5.02 \\ \cline{3-5}  & & & Paint-White & & 5.02 \\ \hline \multirow{2}{*}{6} & \multirow{2}{*}{2} & T8 Trapezoidal Lead Screw Lead Screw Lead Screw + T8 Nut & 8.99 & 17.98 \\ \cline{3-5}  & & & 2 & 5 mm to 8 mm Shaft Coupling & 6.49 & 12.98 \\ \hline \multirow{2}{*}{8} & \multirow{2}{*}{The Attenuation} & \multirow{2}{*}{2} & Nema 17 Stepper Motor & 10.00 & 20 \\ \cline{3-5}  & & & 4 & LML12B Miniature Linear Rail Guide 150 & 7.99 & 31.96 \\ \hline \multirow{2}{*}{10} & \multirow{2}{*}{Actual} & \multirow{2}{*}{2} & EasyDriver Shield Stepper Motor Driver & 5.99 & 11.98 \\ \cline{3-5}  & & & 1 & Mechanical Endstop Limit Switch & 6.99 & 6.99 \\ \hline \multirow{2}{*}{12} & \multirow{2}{*}{1} & Arduino Uno & 9.99 & 9.99 \\ \cline{3-5}  & & & 1 & Lithium Grease & 5.06 & 5.06 \\ \hline \multirow{2}{*}{14} & \multirow{2}{*}{Zero Depth Detection} & \multirow{2}{*}{1} & Alligator Clips Clamps & 1.99 & 1.99 \\ \cline{3-5}  & & & & 52 mm suction cup with M4 screw & 6.49 & 6.49 \\ \hline \multirow{2}{*}{15} & \multirow{2}{*}{26} & \multirow{2}{*}{RS PRO 15 \(\times\) 15 mm 2 Hole Steel Angle Bracket} & \multirow{2}{*}{0.183} & 4.76 \\ \cline{3-5}  & & & 1 & RS PRO M3 \(\times\) 12 mm Hex Socket Cap Screw Black, & \\ \cline{3-5}  & & & Self-Colour Steel (Pack of 100) & 13.98 & 13.98 \\ \hline \multirow{2}{*}{18} & \multirow{2}{*}{Packaging} & \multirow{2}{*}{1} & RS PRO Steel, Hex Nut, M3 & 4.02 & 4.02 \\ \cline{3-5}  & & & 1 & Zinc Plated Steel Plain Washer, 0.5 mm Thickness, M3 & 1.11 & 1.11 \\ \hline \multirow{2}{*}{20} & \multirow{2}{*}{1} & Manufacturing Expenses & \multirow{2}{*}{50} & 50 \\ \cline{3-5}  & & & & Total Cost & 362.46 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Key components used in the measurement device and their costing. The next step is to align the hole-drilling rig using the live camera view. This is followed by using the on-board probing functionality, where the red clamp and the copper plate are used to determine the zero point of the measurement, as shown in Figure 4. Once the z-position is acquired, it is written into the g-code script. The script is written for easy adjustability based on this measurement. With all the arrangements completed, the device is then rehomed. Once ready, the drill is turned on and a reference image is captured. This is followed by running the script in the GUI and starting the measurement. At each increment, the device stops and waits for user input to capture an image.