Nondestructive inspection of curved clad composites with subsurface defects by combination active thermography and three-dimensional (3D) structural optical imaging.

Highlights • The different camera system calibration and matching are simultaneously achieved. • The fusion of 3D digital model to 2D IR image reaches up to sub-pixel accuracy. • Integration active thermography and 3D optical imaging is used for the 3D visualization of defects. Abstract In this paper, a combination active thermography and three-dimensional (3D) structural optical imaging is reported on the nondestructive inspection of curved clad composites with subsurface defects. Artificial points are marked on the background of test objective and helpful to obtain the mapping matrix from two-dimensional (2D) thermal wave characteristic imaging data to 3D spatial coordinate's digital model. The 3D digital model is transformed into a new coordinate system and then reprojected onto the thermal-wave feature image exactly. The fusion of 2D thermal-wave characteristic data and the 3D digital model is achieved by bilinear interpolation. Specimens of carbon fiber reinforced polymer (CFRP) skin-honeycomb sandwich (CFRP-SHS) and High silicon oxygen phenolic resin (HSOPR) sheet with artificial defects are prepared for the experimental investigation. Experimental results indicate that the proposed method can reliably inspect the defects and accurately locate defect positions on the curved surface of CFRP-SHS and HSOPR laminate test sample, and it has a significantly potential for the use of aerospace and aircraft manufacturing and application. [ABSTRACT FROM AUTHOR]