Lamb waves and nearly-longitudinal waves in thick plates

David W. Greve; Irving J. Oppenheim; Peng Zheng

doi:10.1117/12.775919

8 April 2008 Lamb waves and nearly-longitudinal waves in thick plates

David W. Greve, Irving J. Oppenheim, Peng Zheng

Proceedings Volume 6932, Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2008; 69321I (2008) https://doi.org/10.1117/12.775919
Event: SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring, 2008, San Diego, California, United States

Abstract

We discuss waves created in relatively thick plates by edge excitation at frequency-thickness (fd) products that correspond, in principle, to multiple Lamb wave modes. For relatively low values of the fd product it is clear that Lamb wave modes will be generated, while at large values of the fd product we observe a bulk (longitudinal wave) in the solid, but influenced by reflections from the plate surfaces. We show that for a range of intermediate fd products a train of regularly spaced nearly-longitudinal waves is generated. The development of a lead pulse and trailing pulses, all traveling at the longitudinal (bulk) wave speed, is well known and has been explained in the literature. In this paper we describe the transition from Lamb wave generation to the formation of nearly-longitudinal waves with their trailing pulses. We report experimental results and theoretical results, with good correspondence between them. We also examine the transfer of energy from leading to trailing pulses, which means that such nearly-longitudinal waves will not propagate indefinitely; however, we show that they retain ample energy for flaw detection at distances of several meters. Most importantly, we study the interaction of these trailing pulses with cracks, again showing experimental results and theoretical predictions that are consistent with one another. The results suggest that these nearly-longitudinal waves are an attractive option for flaw detection because of their shorter wavelength (as compared to Lamb waves at low fd products) and because they preserve their pulse train characteristics after scattering.

Citation Download Citation

David W. Greve, Irving J. Oppenheim, and Peng Zheng "Lamb waves and nearly-longitudinal waves in thick plates", Proc. SPIE 6932, Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2008, 69321I (8 April 2008); https://doi.org/10.1117/12.775919

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available