Non-destructive characterisation of carbon-fibre-reinforced plastics by means of eddy-currents

Electric Time Domain Reflectometry Sensors for Non-Invasive Structural Health Monitoring of Glass Fiber Composites

“…This change in TDR waveform can be used to access the strain and damage state of the specimen. As the specimen undergoes tensile strain, the TDR voltage increases as predicted by Equation (9). While there is only a small increase in the TDR waveform with strain, there is considerable difference between TDR waveforms of the specimen with and without damage.…”

“…The average impedance is dependent on the effective dielectric constant given by Equation (8). For the parallel plate setup, effective dielectric constant is given by Equation (9). In addition to the geometrical properties of the specimen, there is also a strain dependence of the dielectric constant [22,23].…”

“…While the failure criteria are very well defined for traditional materials such as metals, the failure criteria are much more complicated for composite materials [1]. Hence real time structural health monitoring (SHM) is crucial for composite material structures In this aspect, there has been a recent interest in SHM of composites using fiber optics [2,3], acoustic emission [4,5], ultrasonic [6,7], x-ray radiography [6] and eddy current [8,9] methods. Fiber optic sensors suffer from the weakness of being highly invasive difficult to integrate during composites manufacturing process, and require expensive and complicated instrumentation.…”

Development of Infrared Techniques for Practical Defect Identification in Bonded Joints

“…Eddy current NDE, traditionally developed for highly conductive metals, may also be applied to less conductive carbon fibre composites [67]. The anisotropy of the electrical conductivity of the fibres allows information such as fibre orientation and distribution to be obtained and indications of flaws may be found.…”

Electromagnetic Characterization of Anisotropic and Weakly Conductive Materials by Using Resonant Circuits

“…However, this method is less efficient for weakly conductive materials, such as carbon fiber reinforced polymers (CFRPs) [3][4][5].…”