Location

Snowmass Village, CO

Start Date

1-1-1995 12:00 AM

Description

In this paper, we present a general method for solving wave propagation problems in periodically layered composite plates. Such plates can be divided into periodic cells composed of two or more sublayers with different material parameters. Composite plates behave quite differently from homogeneous plates. Shull et al. [1] observed that guided wave dispersion curves for these plates, unlike their homogeneous counterparts, do not scale with frequency-thickness product. In a recent contribution, Auld et al. [2] presented an analysis for SH wave propagation in periodically layered plates and attributed this phenomenon to the pass-band and stop-band structure caused by the layering. The SH wave analysis is analogous to the electromagnetic case (e.g. periodic microwave filters). However, in ultrasonic practice, the more relevant case is the propagation of Lamb-type waves (polarized in the vertical plane) in periodic plates. This problem is characteristically different from the SH problem due to the coupling between quasi longitudinal and quasi shear wave components. In this paper, we will show how Floquet modes can be utilized to simplify significantly the solution to the plate wave problem with periodic structures. The Floquet modes, which are the characteristic modes for the infinite periodically layered medium, can be thought of as analogous to the longitudinal and shear modes for the infinite homogeneous isotropic medium.

Book Title

Review of Progress in Quantitative Nondestructive Evaluation

Volume

14A

Chapter

Chapter 1: Standard Techniques

Section

Guided Wave Propagation

Pages

179-186

DOI

10.1007/978-1-4615-1987-4_19

Language

en

File Format

application/pdf

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Jan 1st, 12:00 AM

Floquet Analysis of Lamb Waves Propagating in Periodically-Layered Composites

Snowmass Village, CO

In this paper, we present a general method for solving wave propagation problems in periodically layered composite plates. Such plates can be divided into periodic cells composed of two or more sublayers with different material parameters. Composite plates behave quite differently from homogeneous plates. Shull et al. [1] observed that guided wave dispersion curves for these plates, unlike their homogeneous counterparts, do not scale with frequency-thickness product. In a recent contribution, Auld et al. [2] presented an analysis for SH wave propagation in periodically layered plates and attributed this phenomenon to the pass-band and stop-band structure caused by the layering. The SH wave analysis is analogous to the electromagnetic case (e.g. periodic microwave filters). However, in ultrasonic practice, the more relevant case is the propagation of Lamb-type waves (polarized in the vertical plane) in periodic plates. This problem is characteristically different from the SH problem due to the coupling between quasi longitudinal and quasi shear wave components. In this paper, we will show how Floquet modes can be utilized to simplify significantly the solution to the plate wave problem with periodic structures. The Floquet modes, which are the characteristic modes for the infinite periodically layered medium, can be thought of as analogous to the longitudinal and shear modes for the infinite homogeneous isotropic medium.