This paper investigates the scattering characteristics of the fundamental anti-symmetric (A(0)) Lamb wave at through holes in composite laminates. Three-dimensional (3D) finite element (FE) simulations and experimental measurements are used to study the physical phenomenon. Unidirectional, bidirectional, and quasi-isotropic composite laminates are considered in the study. The influence of diffe...

We obtain a general result for the Lamb shift of excited states of multilevel atoms in inhomogeneous electromagnetic structures and apply it to study atomic hydrogen in inverse-opal photonic crystals. We find that the photonic-crystal environment can lead to very large values of the Lamb shift, as compared to the case of vacuum. We also suggest that the position-dependent Lamb shift should exte...

We have studied the formation of relativistic solitary waves due to nonlinearinteraction of strong electromagnetic wave with the plasma wave. Here, our plasma isrelativistic both in temperature and in streaming speed. A set of equations consisting ofscalar and vector potentials together with a third order equation for the enthalpy inphoton gas plasma is obtained analytic...

This paper describes combined experiments and simulations to automate the extraction of ultrasonic guided wave mode arrivals in order to gain quantitative information about large-diameter pipeline coatings. The dynamic wavelet fingerprint technique (DWFT) is used to show differences between unknown coatings as well as to identify the presence of delamination and grinding flaws within the Lamb w...

Ultrasonic welding is a very promising technique for joining thermoplastic composite (TpC) components in aircraft primary structures [1, 2]. The potential introduction of new lightweight structures in civil aviation has been driving the change towards condition-based maintenance (CBM) as an alternative to the regular inspection interval approach [3]. In turn, CBM has been pushing forward the de...

Since today’s aging fleet is now intended to far exceed their proposed design life, monitoring the structural integrity of those aircraft has become a priority issue for today’s Air Force. One of the most critical structural problems is corrosion. In fact the KC-135 now costs $1.2 billion a year to repair corrosion. In this paper, we plan to show the use of Lamb waves to detect material loss in...

The original Lamb system was introduced by Horace Lamb in 1900, [13], as a simple model for the phenomenon of radiation damping experienced by a vibrating body in an energy conducting medium. Examples include vibrations of an elastic sphere in a gaseous medium, electrical oscillations of a spherical conductor, a dielectric sphere with large inductance, relativistic radiation of energy from a co...

Abstract A large eruption occurred on Jan. 15, 2022, at the submarine volcano Hunga Tonga-Hunga Ha’apai, southern Pacific, and atmospheric Lamb wave was observed to have traveled round Earth multiple times with a speed of ~ 0.3 km/s. Here, I compare their ionospheric signatures using data from dense arrays barometers GNSS stations in Japan. confirmed that disturbances passed over Japan least fo...

refractor ambiguities are big problem in seismic refraction method especially in seismic engineering. there can be hidden subsurface geological phenomena such as hidden faults and shear zones which are not simply predicted by the travel-time graph or some geophysical methods. head wave amplitudes are used to show the resolution of refractor ambiguities and the existence of anisotropy in complex...

The use of piezoelectric wafer active sensors (PWAS) for embedded ultrasonic nondestructive evaluation (NDE) is described. PWAS structure and principle of operation are presented. The interaction between PWAS and ultrasonic Lamb waves is modeled and analyzed, and excitation “sweet spots” for preferentially exciting certain Lamb wave modes are identified. Recent trends in guided-wave ultrasonic ...