Thomas James Batzinger

Porosity Measurement in Composites Using Ultrasonic Attenuation Methods

The measurement of porosity content in composites has been an area of interest to the NDE community. Theoretical and experimental work have related ultrasonic scattering to the amount of porosity in composites and metals [1]. By monitoring the frequency dependence of the ultrasonic scattering, information concerning the amount of porosity in the material can be determined. The scattering of ultrasonic waves can be measured by monitoring the attenuation of the waves as they travel through a material. To accurately measure the attenuation associated with material properties such as porosity scattering, corrections must be made to the ultrasonic amplitude data. These corrections concern other ultrasonic loss mechanisms that are attributed to the measurement process such as surface or boundary effects and transducer focus effects.

Numerical Simulation of Ultrasound Wave Propagation in Non‐Stationary Fluids

Ultrasonic forms an important tool in industrial health and process monitoring. In general, ultrasonic wave propagation studies are carried out in a stationary medium. But in certain scenarios, medical application included, it is essential to understand ultrasound path in a non‐stationary medium. In this paper, we quantify the influence of a moving medium on the propagation of ultrasound through a finite element implementation of a modified wave equation. Analytical profile for the velocity of the moving medium is mapped over the spatial domain. Results for the beam drift due to the moving medium for both normal and angular incidence of the wave are presented.

Sensitivity of Time‐Frequency Representations in the Presence of Noise in Guided Waves NDE

Time frequency representation (TFR) of ultrasonic signals plays an important role in describing the propagation and dispersive effects in thin walled structures. In this paper, Generalized time‐frequency representations viz. the Wigner‐Ville distribution, Choi‐William distribution and Short‐Time Fourier Transform are discussed in the context of mode analysis. A comparison on the estimation of various modes and the obscuring interference terms, due to bilinear structure of TFRs, is presented for lamb waves in aluminum plates. Studies on the performance of TFRs in the presence of strong colored noise are presented.