Review of progress, QNDE

This paper demonstrates new parallel computation technology and an implementation for Lamb wave propagation modelling in complex structures. A graphical processing unit (GPU) and computer unified device architecture (CUDA), available in low-cost graphical cards in standard PCs, are used for Lamb wave propagation numerical simulations. The local interaction simulation approach (LISA) wave propagation algorithm has been implemented as an example. Other algorithms suitable for parallel discretization can also be used in practice. The method is illustrated using examples related to damage detection. The results demonstrate good accuracy and effective computational performance of very large models. The wave propagation modelling presented in the paper can be used in many practical applications of science and engineering.

https://iopscience.iop.org/article/10.1088/0964-1726/21/7/075001/pdf

Lamb wave propagation modelling and simulation using parallel processing architecture and graphical cards

Temperature has a significant effect on Lamb wave propagation. It is important to compensate for this effect when the method is considered for structural damage detection. The paper explores a newly proposed, very efficient numerical simulation tool for Lamb wave propagation modelling in aluminum plates exposed to temperature changes. A local interaction approach implemented with a parallel computing architecture and graphics cards is used for these numerical simulations. The numerical results are compared with the experimental data. The results demonstrate that the proposed approach could be used efficiently to produce a large database required for the development of various temperature compensation procedures in structural health monitoring applications. (Some figures may appear in colour only in the online journal)

https://iopscience.iop.org/article/10.1088/0964-1726/22/3/035014/pdf

GPU-based local interaction simulation approach for simplified temperature effect modelling in Lamb wave propagation used for damage detection

The CIVA software platform is developed at CEA-LIST and partners in the aim of simulating non-destructive evaluation. Most of the developed models are based on semi-analytical methods since they aren’t heavy on computation time. The ultrasonic simulation tools in CIVA allow to fully predict a real ultrasonic inspection in a various range of applications which requires the computation of the beam propagated, as well as its interaction with flaws. The purpose of this communication is to describe the methods used to model the beam to flaw interaction. Three kinds of models for the scattering of ultrasound by flaws have been integrated in CIVA: approached analytical solutions, exact analytical solutions and numerical modelling methods. Numerous experimental validations of all the developed models are provided including comparisons between different simulation methods. Perspectives of new developments are finally emphasized.

Modelling of scattering of ultrasounds by flaws for NDT

A refinement of the Kirchhoff approximation to the scattered elastic fields.

The CEA LIST develops the simulation platform CIVA which includes UT, ECT and RT modules. UT simulation is based on semi-analytical models of the ultrasound propagation and scattering and allows to address a wide range of realistic and complex configurations. Over successive versions, CIVA is enriched by the results of the latest modelling research performed by CEA LIST and its partners. This communication focuses on the recent advances and the current trends in CIVA ultrasonic modelling. One important issue concerns flaw scattering and work is being done in order to integrate in the models complex echo mechanisms not yet taken into account. Thus, contribution of head or creeping waves near critical angles to breaking cracks corner echoes, have been recently integrated in to the echo-formation modelling. In parallel, a hybrid model combining finite element code around the defect and semi-analytical modelling of the beam propagation has been developed. Another work in progress concerns the modelling of noise due to ultrasound scattering by microstructure in polycrystalline materials. At last the development of tools dedicated to array techniques remains a major axis of development. On these different topics the new developments are presented and illustrated by examples of applications and validations.

Recent advances and current trends of ultrasonic modelling in CIVA

This paper aims at presenting an overview of the current capabilities of the ultrasonic models of the CIVA software platform (for ultrasonics, eddy current and radiography techniques), developed by CEA‐LIST and partners. Those models are based on semi‐analytical approaches and numerical integration (integral methods upon the surface of probe or the flaw) in order to address fairly complex configurations while keeping reduced computation times. Such skills are obviously reached within the range of validity of the semi‐analytical models, which have to be carefully studied. In this context, benchmarks organized by the World Federation of NDE Centers (WFNDEC) from 2004 have largely contributed, thanks to experimental data and comparison with other codes of the community, to the validation of simulation codes. Those benchmarks were mostly dealing with canonical problems (in terms of probes, component geometry and flaw shapes). This paper aims at summing up the various problems addressed in the benchmarks and their contribution to the extension of UT models in CIVA.

An overview of ultrasonic beam propagation and flaw scattering models in the civa software

For several years, CEA-LIST and partners have been developing ultrasonic simulation tools with the aim of modelling non-destructive evaluation. The existing ultrasonic modules allow us to simulate fully real ultrasonic inspection scenarios in a range of applications which requires the computation of the propagated beam, as well as its interaction with flaws. To fulfil requirements of an intensive use (for parametric studies), the choice has been made to adopt mainly analytical approximate or exact methods to model the scattering of ultrasound by flaws. The applied analytical theories (Kirchhoff and Born approximations, GTD, SOV...) were already described in previous GDR communication. Over the years, this "semi-analytical" approach has been enriched by adaptations and improvements of the existing models or by new models, in order to extend the applicability of the simulation tools. This paper is devoted to the following recent advances performed in the framework of this approach: The SOV method based on the exact analytical model for the scattering from a cylindrical cavity has been extended in 3D to account for field variations along the cylinder. This new 3D model leads to an improvement in simulation of small side-drilled holes. Concerning the geometrical theories of diffraction (GTD), subroutines for calculation of the 2D wedge diffraction coefficients (for bulk or Rayleigh incident waves) have been developed by the Waves and Fields Group and uniform corrections (UAT and UTD) are under investigation. Modelling of the contribution of the head wave and creeping wave to the echoes arising from a wedge. Numerous experimental validations of the developed models are provided. New possibilities offered by these new developments are emphasized.

https://iopscience.iop.org/article/10.1088/1742-6596/269/1/012013/pdf

Recent advances in semi-analytical scattering models for NDT simulation

The TOFD (Time of Flight Diffraction) Technique is commonly used to detect and to characterize embedded disoriented flaws using their edge diffraction echoes. We present a TOFD simulation module which includes GTD coefficients allowing to predict diffraction echoes from embedded planar flaws. Other dedicated development have been added in the CIVA software platform to simulate lateral surface waves, backwall echoes and shadowing effects from flaws. Experimental validations have been performed on various specimen containing rectangular and CAD contour planar flaws with different possible disorientations (tilt, vertical misorientation, skew) and show an overall good agreement between simulation and measure.

S. Mahaut

Papers

Modelling of scattering of ultrasounds by flaws for NDT

Recent advances and current trends of ultrasonic modelling in CIVA

An overview of ultrasonic beam propagation and flaw scattering models in the civa software

Recent advances in semi-analytical scattering models for NDT simulation

Simulation of disoriented flaws in a tofd technique configuration using gtd approach