Open Access. Powered by Scholars. Published by Universities.®
Engineering Science and Materials Commons™
Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 3 of 3
Full-Text Articles in Engineering Science and Materials
A Time-Resolved Method For Nonlinear Ultrasonic Measurements, Stephen D. Holland, Wolfgang Sachse
A Time-Resolved Method For Nonlinear Ultrasonic Measurements, Stephen D. Holland, Wolfgang Sachse
Stephen D. Holland
We describe a time-resolved method for measuring nonlinear ultrasonic phenomena. Current approaches rely on a narrowband measurement of harmonic generation to identify and characterize nonlinearity. Concomitant with these techniques is poor time resolution. We address this limitation with a hybrid narrowband/broadband approach that provides simultaneous time resolution and harmonic isolation for the measurement of weak nonlinearites. We discuss applications and present demonstrative results showing harmonic generation both in water and at a dry contact aluminum-aluminum interface.
Determination Of Plate Source, Detector Separation From One Signal, Stephen D. Holland, Tadej Kosel, Richard Weaver, Wolfgang Sachse
Determination Of Plate Source, Detector Separation From One Signal, Stephen D. Holland, Tadej Kosel, Richard Weaver, Wolfgang Sachse
Stephen D. Holland
We address the problem of locating a transient source, such as an acoustic emission source, in a plate. We apply time-frequency analysis to the signals detected at a receiver. These highly dispersive and complex waveforms are measured for source-receiver separations ranging from 40 to 180 plate thicknesses and at frequencies such that ten to twenty Rayleigh-Lamb branches are included. Re-assigned, smoothed, pseudo-Wigner-Ville distributions are generated that exhibit the expected sharp ridges in the time-frequency plane, lying along the predicted frequency-time-of-arrival relations. The source-receiver separation can be determined from such plots.
Ultrasonic Nondestructive Evaluation Of Fibre-Reinforced Composite Materials - A Review, Vikram K. Kinra, Vinay Dayal
Ultrasonic Nondestructive Evaluation Of Fibre-Reinforced Composite Materials - A Review, Vikram K. Kinra, Vinay Dayal
Vinay Dayal
This paper reviews various ultrasonic nondestructive evaluation techniques applicable to fibre-reinforced composites. The techniques are briefly described and key references are cited. Methods to evaluate the reduced stiffness of composites due to micro-damage are described. Results show that for composites through-the-thickness attenuation increases and stiffness does not change due to transverse cracks, but in-plane stiffness and attenuation changes are substantial and can be measured by the Lamb wave techniques.