Gerard Berthiau

Impact Damage Detection and Identification Using Eddy Current Pulsed Thermography Through Integration of PCA and ICA

Eddy current pulsed thermography (ECPT) is implemented for detection and separation of impact damage and resulting damages in carbon fiber reinforced plastic (CFRP) samples. Complexity and nonhomogeneity of fiber texture as well as multiple defects limit detection identification and characterization from transient images of the ECPT. In this paper, an integration of principal component analysis (PCA) and independent component analysis (ICA) on transient thermal videos has been proposed. This method enables spatial and temporal patterns to be extracted according to the transient response behavior without any training knowledge. In the first step, using the PCA, the data is transformed to orthogonal principal component subspace and the dimension is reduced. Multichannel morphological component analysis, as an ICA method, is then implemented to deal with the sparse and independence property for detecting and separating the influences of different layers, defects, and their combination information in the CFRP. Because different transient behaviors exist, multiple types of defects can be identified and separated by calculating the cross-correlation of the estimated mixing vectors between impact the ECPT sequences and nondefect ECPT sequences.

3-D Modeling of Thermo Inductive Non Destructive Testing Method Applied to Multilayer Composite

In this paper, a 3-D modeling of a thermo inductive nondestructing testing (NDT) technique applied to carbon fiber reinforced polymer (CFRP) composite is presented. A multiscale approach is used to calculate the electromagnetic and thermal field distribution. The relevance of the technique is then discussed for different positions of flaws and the optimal frequency is estimated.

Characterization of anisotropic electrical conductivity of carbon fiber composite materials by a microwave probe pumping technique

Characterization of anisotropic conductivity of thin carbon fiber/poly ether ether ketone (PEEK) composite was investigated by noncontact and nondestructive microwave probe pumping (MPP) technique. The microwave was pumped by a coaxial probe, and the pumped field intensity distribution was measured by a near-field scanning microwave microprobe (NSMM) and a thermography camera. From the measurement and simulation results, it was observed that intensity of the electromagnetic field was higher along the high conductive directions due to the larger eddy current along these directions. Additionally, electrical defect detection by pumping probe technique was investigated. It was observed that the field intensity drastically decreased around the electrical defect. We showed that through an anisotropic field distribution around the pumping probe, an electrical defect of a carbon fiber/PEEK composite can be detected by combination of MPP and NSMM techniques.

Performance Assessment of Induction Thermography Technique Applied to Carbon-Fiber-Reinforced Polymer Material

In this paper, a model is built to evaluate the flaw detection capacity of the induction thermography applied to nondestructive testing (NDT) of carbon-fiber-reinforced polymer composite. A homogenization approach is used to overcome the large-scale factor. The homogenized electric conductivity obtained is used in a 3-D multilayer finite element model. The problem is discretized by hexahedral element to deal with the numeric instability of tetrahedron element in the modeling of thin and strongly anisotropic domain. The distribution of current in the induction coil is also considered to improve the accuracy of the solution. Numerical model is then validated by comparison with measurement. Simulation of an NDT case with induction thermography will be discussed.

Thermo inductive nondestructive testing method applied to CFRP

Purpose – In this paper, a thermo inductive nondestructing testing (NDT) modeling applied to carbon fiber reinforced polymer (CFRP) composite is presented. The paper aims to discuss these issues. Design/methodology/approach – A multi-scale approach is used to calculate the electromagnetic and thermal field distribution. Findings – The temperature perturbation due to the presence of flaws can be detected at the surface of the composite by an infrared camera. Originality/value – The developed 3D thermomagnetic model can be used to study the efficiency of the thermal inductive method for different kind of flaws, inductors and frequencies.

Electrical conductivity tensor modelling of stratified woven-fabric carbon fiber reinforced polymer composite materials

In this paper, a new multi-scale approach to predict the effective electrical conductivity tensor of a woven-fabric composite layer is presented. The result is then used to model the behaviour of a stratified composite material composed by a pileup of woven-fabric layers with different relative orientations. To take into account the orientation and the anisotropy of the material a 3D multilayer hexahedral degenerated elements method is used to model the anisotropic plate. This approach enables to take account random distribution of carbon fibers in the yarns, 3D effects and electric percolation threshold with an acceptable numerical cost. The developed model is then validated by experimental results.

Degenerated Hexahedral Whitney Elements for Electromagnetic Fields Computation in Multi-Layer Anisotropic Thin Regions

In this paper, the use of a degenerated hexahedral Whitney elements method in the modeling of multi-layer anisotropic regions is presented. The elements degenerated from hexahedral elements are used to model laminated composites at the elementary-ply scale considering the circulation of eddy-currents along the thickness of the material. Eddy-current problem is solved using the A - Φ formulation.

Application of Degenerated Hexahedral Whitney Elements in the Modeling of NDT Induction Thermography of Laminated CFRP Composite

In this paper, degenerated hexahedral Whitney elements are used to model carbon-fiber-reinforced polymer composites in nondestructive testing induction thermography technique. These elements avoid meshing the thin regions of composite and consider the anisotropic multilayer characteristic of the materials and also the flaws inside their volume. The eddy-current problem is solved using A - Φ formulation. The accuracy of this method is shown by comparison with the classical hexahedral elements.

Magnetic Response of Anisotropic Metal Fiber Material Using Homogeneous Technique in ECNDT

The 3-D shell elements model is used to determine the sensor impedance variation due to anisotropic metal fiber composite materials (AMFCM). The homogenization of these materials is realized by the inverse problem method. The impedance variation gives the information about the lift off and/or the integrity of the AMFCM

Electrical Conductivity Tensor Modeling of Stratified Woven-Fabric Carbon Fiber Reinforced Polymer Composite Materials

In this paper, a new multi-scale approach to predict the effective electrical conductivity tensor of a woven-fabric composite layer for frequencies lower than 10 MHz is presented. The result is then used to model the behavior of a stratified composite material composed by a pileup of woven-fabric layers with different relative orientations. To take into account the orientation and the anisotropy of the material, a 3-D multilayer hexahedral degenerated elements method is used to model the anisotropic thin plate. This approach enables to take into account random distribution of carbon fibers in the yarns, 3-D effects, and electric percolation threshold with an acceptable numerical cost. The developed model is then validated by results for one anisotropic thin layer.