This paper presents a two-stage numerical model of a meander coil electromagnetic acoustic transducer transmitter operating on the Lorentz force principle. This model was used to predict the ultrasonic A-scan signals for bulk (longitudinal and shear) and guided (Rayleigh) waves in isotropic homogeneous materials. The simulation results agree with the experimental results. The grating effects of the meandering coil, for different coil spacings, are also discussed in this paper. © 2011 Taylor & Francis.

Krishnan Balasubramaniam

Department of Mechanical Engineering

ELECTROMAGNETIC ACOUSTIC TRANSDUCERS

Finite element modelling

Finite element models

Homogeneous materials

Lorentz

MEANDER COIL

MEANDER COIL EMAT

Numerical models

Rayleigh

Simulation result

Two stage

ACOUSTIC TRANSDUCERS

Lorentz force

Shear flow

transducers

Transmitters

Wave propagation

finite element method

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

A two-stage finite element model of a meander coil electromagnetic acoustic transducer transmitter

Nondestructive Testing and Evaluation

This paper reports on a new means of generating higher-order mode clusters of guided waves (HOMC-GW) using a meander-coil (MC) electromagnetic acoustic transducer (EMAT) in plates at frequencies significantly higher than the lower-order plate modes. These wave modes are considerably less dispersive and they occur at much higher frequency¿thickness (f x d) products. Our studies cover the f x d range of 13 to 20 MHzmm. Experimental measurements were carried out on Al plate samples of different thicknesses using three different EMAT coil periods. To understand the generation and propagation characteristics of HOMC-GW with EMATs, several simulations were carried out using 2-D finite element models at different f x d products. These simulations captured all features observed in the experiments. The time¿frequency smoothed pseudo Wigner-Ville distribution (SPWVD) was used to analyze the HOMC-GW modes. Defect detection measurements using HOMC-GW generated using EMATs were made on Al plates with machined defects. © 2012 IEEE.

IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control

Generation and detection of higher-order mode clusters of guided waves (HOMC-GW) using meander-coil EMATs

This paper presents a new method of improving the ultrasonic signal amplitude from a meander line EMAT by using soft magnetic alloy ribbon (Fe 60Ni10V10B20) as a magnetic flux concentrator (MFC). The flux concentrator is a thin soft amorphous magnetic material (Fe60Ni10V10B20) which is very sensitive to a small flux change. The MFC is used with the EMAT to improve the signal amplitude and it was observed that the peak signal amplitude increases by a factor of two compared to the signal without MFC. Two dimensional numerical models have been developed for the EMAT with MFC to quantify the improvement of the received signal amplitudes. Model calculations and experiments have been carried out for a wide range of ultrasonic frequencies (500 kHz-1 MHz) in different materials. © 2011 Elsevier B.V. All rights reserved.

Ultrasonics

Improving the signal amplitude of meandering coil EMATs by using ribbon soft magnetic flux concentrators (MFC)

Sealing Technology

COMSOL Multiphysics Version 4.0 released

Sensors and Actuators A: Physical

A model for pulsed Rayleigh wave and optimal EMAT design

A new magnetic configuration for a small in-plane electromagnetic acoustic transducer applied to laser-ultrasound measurements: Modelling and validation

Applied Physics Letters

Signal enhancement of the in-plane and out-of-plane Rayleigh wave components

Optimising ultrasonic wideband Rayleigh wave generation by pulsed electromagnetic coils

Journal	Nondestructive Testing and Evaluation
ISSN	10589759
Open Access	No