FEM modeling and sensitivity study for low frequency multilayer donut probe inspections

In this work, a finite element model was developed to simulate donut probe inspections in multilayer stackups fastened with bolts. The model was developed to include the effect of adjacent fasteners, bolt angle/properties, and the geometry of the substructure. Experiments were run using samples developed as part of a previous reliability assessment of low frequency electromagnetic techniques. The model was found to be in good agreement with the experiments, and was transitioned to the HPC for large parametric studies. The model development, verification and validation, and the results from the parametric studies accomplished to date are given here.