A Smart Eddy Current Sensor Dedicated to the Nondestructive Evaluation of Carbon Fibers Reinforced Polymers

Abstract

This paper propose a new concept of an eddy current (EC) multi-element sensor for the characterization of carbon fiber-reinforced polymers (CFRP) to evaluate the orientations of plies in CFRP and the order of their stacking. The main advantage of the new sensors is the flexible parametrization by electronical switching that reduces the effort for mechanical manipulation. The sensor response was calculated and proved by 3D finite element (FE) modeling. This sensor is dedicated to nondestructive testing (NDT) and can be an alternative for conventional mechanical rotating and rectangular sensors.

High Radio Frequencies interaction of Composite Materials Using Rectangular Waveguide

“…At 0° the current density is lower than 45° and 90° due to the fibres orientation perpendicular to the electrical field. In addition, the current density direction is following the vertical direction even though that electrical conductivity in the horizontal is bigger than in the vertical direction (σx>> σL), that means that the current density direction is forced to take the lower conductivity direction due to the displacement current which follow the electrical field direction as shown in Figure 6a, indeed the induced currents by the magnetic field this important remarque support this argument in [22] for the field of radio frequency (high frequencies) as well as in low frequencies. Nevertheless, in Figure 5b and Figure 6b the fibers are oriented in 45°, the electrical field is almost perpendicular to the current density but in opposed oblique direction, in this case the electrical field and the current density are the resultant of two principal which they take y and x direction, in addition the opposed oblique direction due to the high conductivity direction in the oblique way which is very effect if compared with the conductivity in x and y directions.…”

“…The new conductivity tensors and permittivity tensor taken into account the fibers orientation angle θ at longitudinal and transverse axis are given by the following equations [21][22][23]: These electrical properties tensors are symmetrical type compared with the previous axial electrical properties (at 0°). In addition these tensors show the effect and interference on the effective conductivity and permittivity when the CFRP is rotating from longitudinal to transverse direction.…”

An Eddy Current Nondestructive Method for Crack Detection in Multilayer Riveted Structures

“…One of the most reliable NDT technique is EC method, this method applied in conductive non-magnetic structures, EC method is based on an alternating electromagnetic reaction phenomena between the source who is generate the electromagnetic field and the tested piece who is in approximation with the source field, the electrical reaction of the plate represent in the creation of the eddy currents, the penetration the induced currents depends on skin thickness effect [3][4][5].…”

“…The electromagnetic reaction between the coil and the tested piece give us a state about the geometric properties and the physical properties, in our case the physical properties such as the electrical conductivity is known, otherwise, the induced currents path are closed contours which depends on the geometric state of the tested piece, which is mean that any deformation in the tested piece will effect on the paths of the induced currents although effect on the impedance variation of the eddy current sensor [5][6][7].…”

Crack Monitoring Method for an FRP-Strengthened Steel Structure Based on an Antenna Sensor

“…Jiang et al [ 5 ] studied an impact detection system based on a fiber Bragg grating (FBG) sensor array and multiple signal classification (MUSIC) algorithm to determine the location and the number of low velocity impacts on a carbon-fiber-reinforced polymer plate. In long-term service, cracks will inevitably appear on steel structures that have been strengthened using FRPs under the influence of external loading and the usage environment [ 6 , 7 ]. Colombi et al [ 8 ] investigated fatigue crack growth in steel beams that were strengthened using carbon-fiber-reinforced polymers.…”