Ultrasonic waves are mechanical vibrations and can be used to determine the structural integrity of materials. High frequency (usually 1 MHz or higher) ultrasonic waves propagating through a material can be used to measure material properties and property changes.
Some of the ultrasonic wave principal applications are:
- Detection of discontinuities
- Thickness measurements
- Determination of elastic constants
- Study of metallurgy
Also, if broad band signals are used to interrogate a material, frequency analysis using the Fourier Transform can be performed and additional information not available in the time domain can be extracted.
Using a computer-controlled high-resolution scanner in conjunction with typical ultrasonic equipment, C-scan images of material can be generated. Among the activities that MISTRAS has performed in the area of traditional ultrasonics is the inspection of Al/SiC Metal Matrix Composites (MMC
) for detection and evaluation of porosity and cracking, as well as bond analysis in Titanium-composite honeycomb joints.
Advanced Ultrasonic Technology
In addition to the traditional Ultrasonic Techniques (UT
) such as immersion pulse-echo, direct and direct contact, MISTRAS has expertise in Advanced Ultrasonic Techniques (AUT
Some of these techniques are:
- Cracking detection and bond evaluation using Ultrasonic Rayleigh and Lamb waves
- Ultrasonic Imaging using Lamb Waves
Ultrasonic Rayleigh and Lamb waves methods are excellent NDE
tool for detecting and characterizing various discontinuities in composite plates, including delaminations, porosity, ply gaps, and variation in resin content. Additionally, they are very sensitive to the characteristics of the plies in composite plates, the bonding degree between layers, and changes in the overall thickness of the plate due to their frequency dependent propagation velocity.