High-frequency electromagnetic non-destructive evaluation for high spatial resolution, using metamaterials

Abstract

This study presents a new high-frequency electromagnetic method for a non-destructive evaluation of metallic strip gratings from printed circuit boards and of some carbon-fibrereinforced plastic composites, allowing the detection of small defects. The electromagnetic transducer is based on a metamaterial lens realized with two conical Swiss rolls, that allows the transmission and intensification of purely evanescent modes generated in the slits of metallic strip gratings and in the dielectric that insulate the carbon fibres between them. The method and the transducer used allow the localization of metallic strip interruptions whose widths are greater than 0.2 mm, the non-alignment of carbon fibres, the breaking of carbon fibres, the lack of resin or delaminations due to impact at low energies, with spatial resolution being greater than 0.1 mm.

Enhancement of spatial resolution using metamaterial sensor in NonDestructive Evaluation

“…One cell of woven carbon fiber has been designed in the The result of the simulation presented in Figure 7b is a snapshot from a field sequence, showing the Hy field progress at a particular slice of the geometry. In this case, the role of conductive strips is taken by carbon fibers, which act as MSG [71]; the apparition of evanescent waves can also be emphasized.…”

“…The theoretical and experimental study of eigenmodes [71] that appear in the studied MSGs open new domains of applications in the eNDE of stratified structures.…”

“…Moreover, working at a frequency that ensures µeff = −1 for the same lens, the magnetic evanescent modes can be manipulated [20,71].…”

Complementary Methods for Evaluation of Yttria Stabilized Zirconia Coatings used as Thermal Barrier Coating

“…S parameters have been measured using Agilent type 4395A coupled with Agilent S Parameter Test Kit 87511A. Assuming the continuous material is characterized by n refractive index and Z impedance relatively simple analytic expression can be found relating n and Z of a slab to the S parameters [23]   …”

“…In the case of CSR, dimension of d is 20 mm (as the diameter of the large basis of the CSR) and k represents the wavenumber of the incident electromagnetic wave in free space, n and Z are related to dielectric permittivity and magnetic permeability by the relations [23] n Z The EM sensor is an absolute sendreceiver type [18,22], and has the principle scheme given in Fig. 1a and its construction in Fig.…”