A Generic Hybrid Model for the Simulation of Three-Dimensional Bulk Elastodynamics for Use in Nondestructive Evaluation

Abstract

Abstract-A three-dimensional generic hybrid model is developed for the simulation of elastic waves in applications in NonDestructive Evaluation that efficiently links different solution strategies but, crucially, is independent of the particular schemes employed. This is an important step forward in facilitating rapid and accurate large-scale simulations and this advances the twodimensional generic hybrid methodology recently developed by the authors. The hybrid model provides an efficient and effective tool for creating highly accurate simulations that model the wave propagation and scattering, enabling the interpretation of inspection data; the new methodology is verified against other numerical simulations. Furthermore, its deployment to simulate wave reflection from side-drilled holes, comparing the results with experimental measurements, provides a realistic demonstration as well as further validation.

Simulating the ultrasonic scattering from complex surface-breaking defects with a three-dimensional hybrid model

“…The method simulates an ultrasonic inspection by breaking it down into two separate domains, the source domain and defect domain, and couples them together using a semi-analytical hybrid interface, illustrated by figure 1; the interface is independent of the techniques used to simulate each domain. The work by Rajagopal et al [9] and Choi et al [10] provide validation of this hybrid technique in 2D and 3D respectively, where good agreement is found in comparison to full numerical simulation and experimental data.…”

“…In this section, we consider the angled beam P-E inspection and determine an accurate approach to apply the hybrid methodology. For the theoretical background of the full hybrid approach in two and three dimensions, the reader is referred to [9] and [10], respectively. To simulate the source domain, we choose to employ a semi-analytical beam model based on the Huygens-Fresnel principle of superposition; previous validation studies have shown it to produce accurate results when modelling a wedge-mounted transduction system [14], which is required here to simulate a shear wave at oblique incidence.…”

“…Equation 3 requires the wave potentials to be measured over the boundary of the defect domain, defined by the surface, , which is referred to as the monitoring surface. The potentials can be calculated from various field quantities; here, they are computed from stress and displacement, which are common outputs of FE solvers, as in [10]. In general, an FE solver will compute the total field, which contains components of both the incident and scattered fields.…”

“…A second FE model without the defect present is required to provide the incident field on the monitoring surface. In previous work, this surface has been defined as a rectangle or cuboid enclosing the defect [9,10]. However, for the case of a surface-breaking defect, the backwall can be considered a semi-infinite stressfree boundary and therefore cannot be enclosed.…”

“…The technique developed by researchers at Imperial College [9,10] offers flexibility in the hybrid methodology, such that it can be adapted to suit specific requirements and applications. The method simulates an ultrasonic inspection by breaking it down into two separate domains, the source domain and defect domain, and couples them together using a semi-analytical hybrid interface, illustrated by figure 1; the interface is independent of the techniques used to simulate each domain.…”