Nondestructive Evaluation of Composite Materials by ESPI

Abstract Electronic speckle pattern interferometry (ESPI) was used to perform nondestructive evaluation of carbon-fiber reinforced plastic (CFRP) laminate plates containing various sizes and shapes of defects located at different depths. A specially designed vacuum box was used to provide the deformation of the test specimen. Not the same as the traditional ESPI, the decorrelation between two speckle patterns was used to determine the size, and shape of a defect. By using the speckle decorrelation, the location, size and shape of a defect can be easily determined. A series of computer programs was developed on the ESPI system to acquire and analyze the interferometric patterns. Although the detected shape and size do not match well with the originally embedded one, the ESPI procedures developed in this paper should still be a potentially quantitative nondestructive method for detecting the location and size of the defect in composite materials.