Development of circular arrayed eddy current sensor for detecting fibers orientation and in-plane fiber waviness in unidirectional CFRP

This paper proposes a circular arrayed eddy current non-destructive testing sensor for detecting fibers orientation and in-plane fiber waviness defects in unidirectional carbon fibers reinforced polymer (CFRP). The design procedure involves two steps, the application of the rotating rectangular sensor principle on a pair of coils. In this case, to test the used simulation method, the results are experimentally verified. In the second step, the resulted form is exploited to simulate a circular arrayed sensor. This sensor allows the cancellation of the mechanical rotation of the conventional sensors and it permits to reduce the inspection procedure duration. The electromagnetic phenomena are calculated by using 3D finite element method (FEM) based on the electromagnetic AV-A formulation. Then, the sensor responses are analyzed through polar diagrams of the impedance variation. The circular arrayed sensor is used to characterize a unidirectional CFRP and to detect the in-plane fiber waviness in a layer of CFRP.