A. Ardebili, M.r. Farahani,
Volume 20, Issue 9 (9-2020)
Abstract
Thermal image analysis can be used to identify and detect patch defects in the interface between multilayer sheets. Specimens made for testing were carbon fiber and glass fiber patches on aluminum sheets that were embedded in composite patch layers, for interlayer separation, in different metal-patch joints. The defect pattern was designed so that the bugs at the edge and center of the patch were tested simultaneously. In this study, the effects of depth and dimension of separation faults with pulsed heat treatment were identified and investigated. Then, the factors affecting the accuracy of the identified defect size were investigated. In the thermal images obtained, almost all the defects can be identified by pulsed thermography and with increasing the size of the defect the thermal difference with the sound areas increases. It was found that the defects in the carbon fiber field were up to an average of 1°C, there was a greater thermal difference than that of glass fiber field. However, the results showed that the accuracy of the measurement of defects in glass fiber was 2 times higher than that of carbon fiber.
Mohammad Amin Zarezadeh Mehrizi, Mohammadreza Farahani, Majid Safarabadi, Mojtaba Rezaee Hajideh, Majid Farhang,
Volume 24, Issue 12 (11-2024)
Abstract
In thermal barrier coatings (TBC), surface cracks, debonding, and thickness degradation may occur during the manufacturing process or life cycle, leading to poor performance and ultimately a dangerous system failure. The main goal of non-destructive testing of thermal barrier coatings is to detect these defects and determine the health of the coating. Various non-destructive inspection methods have been proposed to evaluate thermal barrier coatings, and due to the numerous advantages of thermography, including high speed, low cost, safety, no need for direct contact, automation capability, and inspection of a large area of the part, this method has received special attention from researchers. This study will present a method for manufacturing samples with different diameters of artificial separation defects. The following is the equipment's arrangement and the sample's thermography process. It was concluded that blackening the surface of the sample by increasing the amount of thermal energy absorption increased the ability to identify separation defects and increased the signal-to-noise ratio by 257%. Finally, by implementing different filters on the recorded raw thermal images, it has been shown that in both cases the best filter in terms of SNR is the median filter and then the Gaussian filter. The background removal filter also had no noticeable effect on increasing the signal-to-noise ratio and acted as a complement to the median and Gaussian filters by reducing the fixed error
