| In response to the crisis of crack detection, a group of researchers from Wayne State University have developed a novel hybrid ultrasonic/infrared nondestructive technique, in short Sonic IR (SIR)* imaging, with applications including but not limited to detecting cracks in metallic structures such as aircraft fuselage skin and disbonds and delaminations in composite structures such as that made of honeycomb core.; The technique uses a short ultrasound pulse usually either 20KHz or 40KHz frequency to infuse the sample with. This causes the crack surfaces to interact with each other thus generating heat in the process due to friction and other irreversible internal surface interactions in the proximity of cracks or disbonds. The heating is then observed through an infrared (IR) video camera. A custom-made software is used for image processing.; The current study attempts to evaluate the technique for detecting surface breaking cracks and investigate the differences between chaotic and non-chaotic pulses and to show quantitatively which one is better and why. (Abstract shortened by UMI.)... |
