Probability of Detection Analysis of Frequency Modulated Thermal Wave Imaging to Glass Fiber–Reinforced Composite Materials for Nondestructive Testing

Abstract

Abstract The probability of detection (POD) is the minimum detectable size of defects that helps in selecting an appropriate method for nondestructive testing (NDT) for a particular application and it is usually expressed as a function of defect size or aspect ratio (dimension/depth). It is a measure of the efficiency of an inspection process which is used to quantify the capability of the NDT method. For characterizing and quantifying the inspection capability and reliability of the method, POD curves are analyzed. The objective of this study is to measure the efficiency of an image processing algorithm that can locate defected areas that may be present in the analyzed sample in a completely automated way. In this article, for Frequency Modulated Thermal Wave Imaging (FMTWI), different data processing algorithms are compared by POD curves. POD curves of different segmentation algorithms for different processing algorithms are also carried out and compared with the proposed segmentation algorithm. The POD curves of the hit/miss data processing are used for estimating the detection capability and FMTWI image of glass fiber–reinforced composites, and the effects of the defect aspect ratio with 90 % POD (r90) and the defect aspect ratio for which a 90 % POD is reached at the 95 % confidence level (r90/95) on POD curves are compared.