Defect indications in sono-thermography in relation to defect location and structure

Abstract

A high power ultrasonic burst excitation technique was used to study the potential of the ultrasound excited thermography (vibro-or sono-thermography) to detect and to estimate the depth position of cracks in ceramics as well as voids in glass fibre reinforced polymer. By verification using high-frequency (50 MHz) ultrasound techniques it was proven that sono-thermography can detect relatively deep defects in ceramics. The depth of the defect can be estimated using a theoretical model based on analytical calculations dealing with friction heat sources equally distributed over the crack flanks stimulated by the ultrasonic vibrations of the specimen. In carbon fibre reinforced polymers, the thermographic indications of defects were correlated with 3D X-ray cross sections of the specimen.

Structural health monitoring for a wind turbine system: a review of damage detection methods

“…High power ultrasound [47] or oscillating stress can be applied to a sample, for thermography, by vibrating it with a mechanical shaker [43]. The capability of this method, called vibro-thermographic or sono-thermographic, to locate and evaluate the size of cracks and impact damage is proven.…”

Investigations on active thermographic testing techniques for manufacturing processes

“…For glass fibre reinforced plastic components, there was a good correlation between thermal signals and the internal structure as obtained from 3D X-ray tomography [1].…”

Structural health monitoring of offshore wind turbines: A review through the Statistical Pattern Recognition Paradigm

“…This technique has been proven to be useful in WT blades fatigue tests [61,66], as stress concentrations during the test can be observed before damage in the surface can be appreciated. A promising variation of this methodology involves applying high power ultrasounds [67], or oscillating stresses with a mechanical shaker, to the surface that is being tested [65]. This technique is called vibro-thermographic and is able to locate and assess crack dimensions, as [67] states.…”

“…A promising variation of this methodology involves applying high power ultrasounds [67], or oscillating stresses with a mechanical shaker, to the surface that is being tested [65]. This technique is called vibro-thermographic and is able to locate and assess crack dimensions, as [67] states. Furthermore, it can be used for assessing voids and stress concentration in composites.…”