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Fundamentals of Guided Elastic Waves in Solids

Physical Monitoring Principles

Physics-based and Data-driven Modeling of Structural Component Behavior

  1. Carlos E. S. Cesnik,
  2. Ajay Raghavan

Published Online: 15 SEP 2009

DOI: 10.1002/9780470061626.shm002

Encyclopedia of Structural Health Monitoring

Encyclopedia of Structural Health Monitoring

How to Cite

Cesnik, C. E. S. and Raghavan, A. 2009. Fundamentals of Guided Elastic Waves in Solids. Encyclopedia of Structural Health Monitoring. .

Author Information

  1. University of Michigan, Department of Aerospace Engineering, Ann Arbor, MI, USA

Publication History

  1. Published Online: 15 SEP 2009

Abstract

Guided-wave (GW) approaches have shown good promise as structural health monitoring (SHM) algorithms. However, to achieve their full potential, a sound understanding of the fundamentals of GWs in solids is very desirable and that is the objective of this article. After a brief introduction to the field of GW SHM, it starts with the simplest equation of elastic waves, that of one-dimensional (1D) waves in a taut string. It covers basic concepts of 1D elastic waves to enable an understanding of fundamental concepts and nomenclature relating to wave theory. It then builds on these ideas to derive the 3D elasticity equations of free GWs (Lamb and horizontal shear waves) in isotropic plates. The notion of dispersiveness of GWs is then explained. This is followed by a brief derivation of the GW field excited by finite-dimensional piezoelectric wafer transducers in isotropic plates based on the authors' earlier work. Subsequently, the equations of bulk waves in transversely isotropic solids are covered and these are used to build the solution for free GWs in multilayered fibrous composite laminates using the global matrix approach. The concept of GW steering in composites is discussed. Finally, more complex research issues in GW SHM are briefly introduced.

Keywords:

  • guided waves;
  • lamb waves;
  • dispersion;
  • piezoelectric transducers;
  • finite-dimensional actuators;
  • steering;
  • fibrous composites;
  • multilayered laminates