Wave scattering analysis implemented by boundary element methods (BEM) and the normal mode expansion technique is used to study the sizing potential of two-dimensional shaped defects in a wave guide. Surface breaking halfelliptical shaped defects of three opening lengths (0.3, 6.35 and 12.7 mm) and through-wall depths of 10–90% on a 10 mm thick steel plate were considered. The reflection and tr...

Lamb waves are dispersive in a plate and elastic properties of anisotropic materials are dependent on the crystal orientation. It is expected that the wave propagation on a thin anisotropic plate is complex due to dispersion of Lamb waves which will be dependent on the propagation direction. Therefore it is essential to understand elastic waves in an anisotropic plate. In the present work, a si...

Lamb waves have shown a great potential in structural health monitoring (SHM) of thin plates that are frequently used in engineering structures. Dense transducer networks or active ultrasonic arrays can be employed to generate and receive Lamb waves. Active arrays, however, enable beam steering and can work as spatial filters enabling assessment of large plate areas from a single fixed position...

| Damage detection using guided Lamb waves is an important tool in Structural health Monitoring. In this paper, we outline a method of obtaining Lamb wave modes in composite structures using two dimensional Spectral Finite Elements. Using this approach, Lamb wave dispersion curves are obtained for laminated composite structures with different fibre orientation. These propagating Lamb wave modes...

Lamb waves are currently used in many nondestructive testing applications to determine or monitor elastic properties of plate-like Structures using various excitation methods. The methods vary from point-like dry contact transducers and laser ultrasound techniques in hostile environments to wedge transducers for inspection of excitation of Lamb waves in 2-D geometry by surface immersed structur...

Lamb waves are frequently used in nondestructive evaluation and are proposed for structural health monitoring applications. While many numerical methods to obtain dispersion curves for Lamb waves have been developed and implemented, in general they are time consuming and do not lend themselves to analyses involving the perturbation of parameters such as the small thickness and wave speed change...

The model developed in this paper allows to predict the propagation of Lamb waves in an anisotropic wafer. More generally it can account for the linear dispersive propagation of scalar waves in an anisotropic and finite plate and for any local alteration in the displacement component of the Lamb Wave. The validation has been done using a solid-solid contact as an emitter-receiver.

Piezoelectric transducers have been widely used for the generation and detection of ultrasonic waves for structural health monitoring. Recently, we proposed the use of inductive coupling in order to implement wireless coupling to a Lamb wave transducer. In that transducer the ultrasonic waves were generated by a piezoelectric wafer attached to the surface of a plate. These transducers are effec...

Guided waves based methods are widely used for damage detection and localization in metallic and composite structures. Success of the method application depends on many factors like sensors/actuators location, sensor electronic system design, sensor shape, frequency range of excitation waves and applied signal processing procedures. Authors developed new modified LISA and EFIT algorithms to sol...

Structural health monitoring (SHM) is a major component of the vehicle health monitoring (VHM) concept currently considered for the civilian and military aerospace applications. Piezoelectric wafer active sensors (PWAS) are one of the candidate embedded sensors considered for SHM applications. PWAS are inexpensive, non-intrusive, un-obtrusive, devices that can be used in both active and passive...