Metal Laser Marking for Wind Tunnel Model Displacement Measurements Using Digital Image Correlation

Digital image correlation (DIC) has been used in structural testing to provide full-field displacement and strain data, and wind tunnel testing has been used to measure aerodynamic response for validation of aerodynamic computational codes. Aerodynamic computational codes use the outer mold line as the boundary of the aerodynamic shape. However, deformations of the wind tunnel model can cause changes in the measured aerodynamic performance, thereby degrading the correlation between the wind tunnel and computational results. Incorporating accurate OML data as measured from wind tunnel structural response can improve measured and computational aerodynamic data correlation. Therefore, a metal laser marking process is proposed for use with DIC as a means to provide the necessary fidelity for wind tunnel displacement measurements without affecting the measured aerodynamic data. The laser marking processes is presented, followed by laser marking and testing procedures to determine the laser marking parameters. Lastly, two laser marking systems configurations are described.