In ultrasonic nondestructive testing (NDT) of materials, pulse-echo measurements are masked by the characteristics of the measuring instruments, the propagation paths taken by the ultrasonic pulses, and noise. This measured pulse-echo signal is modeled by the convolution of the defect impulse response and the measurement system response, added to noise. The deconvolution operation, therefore, s...

We describe a new nondestructive evaluation technique which makes cracks and adhesion defects visible to infrared cameras. This is accomplished by infusing the sample with a short pulse of low frequency ultrasound. The sound causes the faying surfaces of defects to heat up by friction or clapping, and thus makes them visible in the infrared. Surface or near-surface defects appear to the camera ...

This paper describes a threefold method of testing the performance of an array-based ultrasonic tool for nondestructive testing of spot welds. The tool is described in its capabilities, use, and advantages over existing counterparts. Performance testing for and the results from carrying out the testing are described. The three performance testing methods include 1) the use of calibrated samples...

1.1 This test method covers guidelines for utilizing EMAT techniques for detecting material discontinuities that are primarily open to the surface (for example, cracks, seams, laps, cold shuts, laminations, through leaks, lack of fusion). This technique can also be sensitive to flaws and discontinuities that are not surface-breaking, provided their proximity to the surface is less than or equal...

The UT simulation tools developed at the French Atomic Energy Commission (CEA) in the CIVA software platform were up to now limited to methods based on bulk ultrasonic waves. This study aims at extending the capabilities of the models to deal with testing configurations using surface acoustic waves (SAW). In such configurations, specific transducer arrangement is made to generate and receive su...

In ultrasonic nondestructive evaluation (NDE), flaw characterization is inhibited by the effects of the measurement system and by acoustic noise due to non-flaw related scattering of the sound. The Wiener filter can be formulated to optimally remove the effects of the measurement system and suppress the noise; however, prior information must be available abeut the neise and flaw distributions, ...

We demonstrate high-speed terahertz (THz) reflection three-dimensional (3D) imaging based on electronically controlled optical sampling (ECOPS). ECOPS enables scanning of an axial range of 9 mm in free space at 1 kHz. It takes 80 s to scan a transverse range of 100 mm × 100 mm along a zigzag trajectory that consists of 200 lines using translation stages. To show applicability of the imaging sys...

We present a theoretical study on the tunability of phononic band gaps in two-dimensional phononic crystals consisting of various anisotropic cylinders in an isotropic host. A two-dimensional plane-wave expansion method was used to analyze the band diagrams of the phononic crystals; the anisotropic materials used in this work include cubic, hexagonal, trigonal, and tetragonal crystal systems. B...

Comprehensive and accurate inspections of welded components have become of increasing importance as NASA develops new hardware such as Ares rocket segments for future exploration missions. Simulation and modeling will play an increasing role in the future for nondestructive evaluation in order to better understand the physics of the inspection process, to prove or disprove the feasibility for a...