CIVA Software Research Articles

Comparisons of ray and finite element simulations of ultrasonic wave fields in smoothly inhomogeneous austenitic welds of thick-walled components

This work addresses the crucial challenges of simulating ultrasonic inspections in welded parts. We focus on the simulation of radiated ultrasonic fields in welded materials, incorporating spatially varying anisotropy and damping properties. Using macroscale descriptions to capture variations in weld properties as a function of grain orientation, two simulation methods are evaluated: a ray method and a hybrid finite element solution within the CIVA software. Simple simulations validate both models, but complexities emerge in real-world scenarios, notably caustic phenomena and beam splitting due to specific grain orientations. The proposed hybrid FE model can therefore provide reliable reference solutions, even for 3D configurations, allowing the biases arising from radius approximations to be quantified.

TFM imaging simulations of defects near or in the weld bevel: modelling approach and customized finite element tools

In safety-critical industries, including the nuclear sector, ultrasonic testing (UT) of welded components is an area of continuous improvement. We have collaborated on developing advanced UT simulation tools to address challenges in monitoring and imaging defects near or within a weld bevel. These tools, integrated into the CIVA software platform, use hybrid approaches combining ray models and finite elements (FE) to accurately simulate wave propagation and diffraction phenomena in both 2D and 3D inspection configurations. While computation time is longer compared to ray-based approaches, the results serve as a reference for improving reliability and validating simulation tools. A comprehensive parameterization of the weld is proposed, utilizing knowledge on anisotropy, attenuation properties, and variations within the bevel, to achieve reliable UT results. This paper reviews the new features developed, including the integration of the MINA model for the weld description and improvements in bevel geometry. The automated coupling methodology and meshing procedures, which do not require any specific numerical expertise to be used, are discussed. As an application, we present TFM imaging simulations, comparing results from the standard paraxial ray-based approach with the new module utilizing the FE computational core.

Using Modeling and Metamodels for Reliability Study in Non-Destructive Evaluation

As in any other measurement process, NDE is subject to variability whose impact can be assessed to guarantee a given level of performance. Once NDE prevents catastrophic failures, deaths and environmental damage, identifying uncertainties and variability in NDE help to design more reliable inspections, therefore is a process that saves lives. This is the goal of a reliability study. Statistical indicators such as Probability of Detection (POD) curves give insights to allow building of mechanical designs with enough « secure margin » for structural integrity and to also define appropriate maintenance & inspection cycles. Simulation is very useful to support performance or reliability demonstrations that require a lot of data (such as POD studies and qualification campaigns), and where simulation can help by reducing the number of necessary mock-ups and experimental trials. In addition to physical models, the NDE simulation software CIVA now offers meta-modelling techniques. Built from an initial set of physical simulations, such surrogate models give the user the possibility to generate a massive amount of data while combining and exploring multi parametric variations. This is particularly efficient in the context of reliability studies, when you have to find the best settings, track the worst-case scenario or build POD curves. This paper illustrates the use of this meta-modelling approach for the reliability study of a longitudinal weld AUT inspection. Real pipe mill inspection data are provided and compared to modelling and meta-modelling results.

Comparative Analysis of Ultrasonic Phased Array Detection and CIVA Simulation

The selection of an ultrasonic phased array inspection process has a great impact on the inspection results. For specific workpieces and processes, CIVA simulation can be used to quickly analyze the imaging effect, which is of great significance for process optimization. In this paper, CIVA software is used to carry out phased array detection simulation of defect holes in specific areas of phased array B-type test block, the same process is used to carry out actual phased array detection, and the positioning and quantitative accuracy of each defect hole is compared and analyzed. The results show that the difference between CIVA simulation and actual detection results is small, and the actual detection accuracy is slightly better than CIVA simulation.

Validation of Novel Ultrasonic Phased Array Borehole Probe by Using Simulation and Measurement

Low-frequency ultrasonic testing is a well-established non-destructive testing (NDT) method in civil engineering for material characterization and the localization of cracks, reinforcing bars and delamination. A novel ultrasonic borehole probe is developed for in situ quality assurance of sealing structures in radioactive waste repositories using existing research boreholes. The aim is to examine the sealing structures made of salt concrete for any possible cracks and delamination and to localize built-in components. A prototype has been developed using 12 individual horizontal dry point contact (DPC) shear wave transducers separated by equidistant transmitter/receiver arrays. The probe is equipped with a commercially available portable ultrasonic flaw detector used in the NDT civil engineering industry. To increase the sound pressure generated, the number of transducers in the novel probe is increased to 32 transducers. In addition, the timed excitation of each transducer directs a focused beam of sound to a specific angle and distance based on the previously calculated delay time. This narrows the sensitivity of test volume and improves the signal-to-noise ratio of the received signals. In this paper, the newly designed phased array borehole probe is validated by beam computation in the CIVA software and experimental investigations on a half-cylindrical test specimen to investigate the directional characteristics. In combination with geophysical reconstruction methods, it is expected that an optimised radiation pattern of the probe will improve the signal quality and thus increase the reliability of the imaging results. This is an important consideration for the construction of safe sealing structures for the safe disposal of radioactive or toxic waste.

Influence of the defect characteristic in aluminum alloy 7075 in non-destructive electromagnetic testing

The paper presents the results obtained from aluminum alloy 7075 T6 using eddy current testing method (ECT). This method is based on eddy current 3x3 sensor array, commanded through PC by a data acquisition system, allowing several different delay and amplitude technique at transmission and reception. The response of each sensor is stored, ensuring details for reconstructions and imaging procedures. Based on software CIVA simulation and experiment, defect characterization is obtained using the information received by each sensor of the array and establishing the position of the flaw upon the reacting sensor from array. The signal is post processed using super resolution algorithm to enhance signal to noise ratio, thus both surface and under surface flaws shall be identified, (thin or volumetric) or having different tilting reported to the surface and correlation between theoretical and experimental results.

Construction and validation of a novel phased array borehole probe for ultrasonic investigations at sealing structures in radioactive repositories

A new type of ultrasonic borehole probe is developed for the quality assurance of sealing structures in radioactive waste repositories using existing research boreholes. The goal is to examine the sealing structures made of salt concrete for possible cracks, delamination, and embedded objects. A prototype probe uses 12 individual dry point contact (DPC) horizontal shear wave transducers separated by equidistant transmitter/receiver arrays, each made up of six individual transducers. It is operated with a commercially available portable ultrasonic flaw detector used in the civil engineering industry. To increase the generated sound pressure of the borehole probe, the number of transducers in the novel probe is increased to 32. In addition, timed excitation of each probe is used to direct a focused sound beam to a specific angle and distance based on calculated time delays. Hence, the sensitive test volume is limited, and the signal-to-noise ratio of the received signals is improved. This paper presents the validation of the newly developed phased array borehole probe by beam computation in CIVA software and experimental investigations on a semi-cylindrical test specimen to investigate the directional characteristics. In combination with geophysical reconstruction techniques, an optimised radiation pattern of the probe is expected to improve the signal quality and thus increase the reliability of the imaging results. This is of great importance for the construction of safe sealing structures needed for the disposal of radioactive or toxic waste.

FEM-based simulation tools for ultrasonic concrete inspection

The simulation of nondestructive evaluation is a useful tool in the design of inspection procedure or the interpretation of results. In the case of the ultrasonic inspection of concrete, modeling the complex interaction of ultrasonic waves with the heterogeneous material is challenging. A finite element code for the simulation of ultrasonic inspections is developed in the CIVA software platform. It is the kernel of a new simulation module dedicated to concrete in a custom version of CIVA. This module relies on automated meshing managed through a user-friendly interface and offers comparatively fast numerical computations. Its aims at modeling practical concrete inspection configurations, involving for example distributions of aggregates, voids and metallic objects. In this communication, we present these modelling efforts and focus on configurations of interests and evaluation of the modelling performances performed in a recent collaboration between CEA and EDF.

Simulation-based deep learning model for the detection of imperfections in concrete structures

The objective of the current study is the development of a deep learning model in order to detect and characterize relevant imperfections in steel reinforced concrete. Especially structural noise can affect the signal quality and needs to be considered. The application of deep learning algorithms requires a large and complete data set. However, experimental data acquisition is limited due to the designs and fabrication of test samples. Consequently, training a model only using experimental data is hardy possible in the current case. Hence, in this study various virtual ultrasonic inspections are conducted with the commercial simulation software CIVA. The simulation takes into account structural noise in order to model the imperfections as realistic as possible. Different types of imperfections are considered such as honeycombs. Using simulation offers the chance to generate a large data set which is required for the training of deep learning models. Furthermore, the parameters can be systematically varied within the simulation which guarantees a complete data set. The simulated inspection data which contains noise is used to train a deep learning model with the internally developed software Echolyst A.I.. Finally, the model is validated with experimental data of honeycomb inspections. The study shows the potential of artificial intelligence in order to significantly increase the effectivity of ultrasonic inspections of imperfections in steel reinforced concrete structures.

Computer Aided Design of Ultrasonic Test by Numerical Simulation

Ultrasonic tests of dissimilar metal welds require extremely sophisticated technology. The complexity of the test is caused by the grain orientation and difficult accessibility of the weld and it is therefore necessary to redound the examinations by simulation. This study details some application possibilities of CIVA software and presents an example of the evaluation of the procedure used for the given test method with probability of detection curves.

Experimental Validation of Transient Spectral Finite Element Simulation Tools Dedicated to Guided Wave-Based Structural Health Monitoring

Abstract In guided wave structural health monitoring (GW-SHM), a strong need for reliable and fast simulation tools has been expressed throughout the literature to optimize SHM systems or demonstrate performance. Even though guided wave simulations can be conducted with most finite elements software packages, computational and hardware costs are always prohibitive for large simulation campaigns. A novel SHM module has been recently added to the civa software and relies on unassembled high-order finite elements to overcome these limitations. This article focuses on the thorough validation of civa for SHM to identify the limits of the models. After introducing the key elements of the civa SHM solution, a first validation is presented on a stainless steel pipe representative of the oil and gas industry. Second, validation is conducted on a composite panel with and without stiffener representative of some structures in the aerospace industry. Results show a good match between the experimental and simulated datasets, but only if the input parameters are fully determined before the simulations.

TOTAL FOCUSING METHOD BASED ULTRASONIC PHASED ARRAY IMAGING IN THICK STRUCTURES

Abstract Ultrasonic non-destructive testing traditionally uses a conventional monolithic transducer. An approach similar to this comprising of independent single transmissions but with reception performed by all the elements in phased array ultrasonics is known as Full Matrix Capture (FMC). The acquired data is processed by Total Focusing Method (TFM). Conventional FMC-TFM has limitations in the inspection at large depth in attenuating materials due to single element transmission. To improve the beam forming process, coherent recombination of the plane wave with specific angles is utilized in transmission and the same aperture is used for the reception in Plane Wave Imaging (PWI). A new methodology called Angle Beam Virtual Source FMC-TFM (ABVSFMC-TFM) is proposed to inspect thick attenuating materials such as nickel base alloys. The ABVSFMC method leads to improved Signal to Noise Ratio (SNR) as compared to the conventional FMC due to increased energy with directivity during transmission using a group of elements and improved divergence as compared to the PWI due to a small virtual source near the sample surface. In the present paper, FMC-TFM, PWI-TFM and ABVSFMC-TFM methods are compared for inspection of thick nickel base superalloy (Alloy 617) with slots at various depths in the range of 25-200 mm. Optimization of the incidence angle has been performed by beam computation in CIVA software. Results obtained by CIVA simulations are discussed and also compared for the three methods.

Jules Horowitz Reactor Irradiation Devices: Inspection Methods proposal

Jules Horowitz Reactor (JHR) irradiation test devices (so called ADELINE and MADISON) must undergo a periodic inspection every 40 months (French ESP(N) Regulation). The first step of inspection proposal was performed from October 2019 to March 2020 and concerns application of non-destructive methods for electron beam welds, while examining the possible methods and locations that could be utilized. This study has been performed in collaboration between VTT Technical Research Centre of Finland Ltd and French CEA with VTT employee secondment at CEA Cadarache. The initial conclusions of this work are the following: • Two inspection methods are likely needed. • Eddy current is likely suitable for surface examination while volumetric ultrasonic inspection can be used for tube bodies. • Inspection under-water in a storage pool (EPI) is likely the best option for location in the JHR. • Some automation and remote controls will be needed during the inspection process. The inspection area is quite large as the whole tube bodies will be inspected. • Internal surfaces located between the nested tubes likely cannot be inspected for corrosion and therefore, sealing the space from oxygen and water will be likely be the best option. • Experimental reference is a critical next step of the work to assess and qualify the inspection methods. As the next step, CEA will continue discussions on requirements of the mock-ups: for eddy current inspection, a Zircaloy-4 planar specimen with artificial reflectors is needed. For ultrasonic reference, a representative mock-up of the cylinder with a weld and artificial defect(s) is needed. The mock-up testing will provide an experimental reference to CIVA calculations as simulations of this work have been performed with CIVA software, which is extensively used in the industry and research organizations in simulation of non-destructive control. This study will allow further steps in the future, up to the qualification of inspection methods for JHR test devices.

Numerical simulations in support of the design of an ultrasonic device for sub-assembly identification

In this paper, it is shown how numerical simulations can help designing an ultrasonic instrument operating in harsh conditions. To prevent fuel handling errors in sodium cooled fast reactors, the identification of fuel sub-assemblies using ultrasound is being investigated. It is based on the interpretation of a code (aligned notches) engraved on the sub-assembly head using an emitting/receiving ultrasonic sensor. This reading is performed in liquid sodium with high temperature (up to 600°C) transducers. A first experiment in liquid sodium demonstrated the feasibility of this method. The reading quality and robustness depend on various parameters related to the ultrasonic beam (spectral response, focal distance, focal spot size), the code geometry (especially the notches’ dimensions) and geometrical alignments. In order to avoid numerous experiments, two numerical models are developed. The first one is a finite element simulation of the sensor providing its radiated field. This model is validated with the well-known analytic solution of the Rayleigh integral; then it is applied to the sensor used in the sodium experiment. The focal distance and focal spot diameter are close to the expected values. The second simulation, using CIVA software, provides the ultrasonic scan of the code. The result is in good agreement with the sodium experiment and a first comparison with a water experiment shows that this numerical tool is relevant for easily taking into account misalignment and misorientation of the scan.

Ultrasound Array Probe: Signal Processing in Case of Structural Noise

Abstract This work focuses on non-destructive examinations using array probe ultrasonic waves on complex materials generating a high structural noise on the examined area. During an ultrasonic examination, multiple scattering of the ultrasonic waves at the grain boundaries makes the distinction between this structurally induced noise and a potential defect challenging. The difficulty of the interpretation can moreover be increased in the near surface area because of the subsurface wave. In order to ease the analysis of these acquisitions, some numerical processing methods are proposed. Statistical properties of the imaging results (for instance, total focusing method or plane wave imaging) are first calculated on several sensor positions. These statistical properties are then used to post-process the imaging results and enhance any signal values that do not belong to the structural noise expected statistics. The method, called “CORUS,” has been successfully tested on cast austenoferritic stainless steel coarse-grained mock-ups, with several dB gain compared to the classical total focusing method. It is now integrated in a civa software plugin and in a prototype version of the real-time PANTHER-phased-array acquisition system from Eddyfi Technologies.

Development of phased array ultrasonic system for detecting rail cracks

In this study, a phased array ultrasonic system for detecting rail cracks (PAUSR) was developed which consists of two phased array (PA) ultrasonic transducers, a water tank, a display monitor, a battery, a commercial 64 channel PA board, and its control software. To accomplish this, the acoustic fields and crack detection images of newly developed PA ultrasonic transducers were simulated and analyzed by the CIVA (CIVA 2016, NDE CIVA, USA) software. The major design factors for the PAUSR is the capability of evaluating crack size (over 2 mm), generating proper acoustic fields in the rail and easy and safe handling for operators. For the performance test of the designed PA ultrasonic transducer, Non-destructive Characterization and Verification of Ultrasonic Phased Array Equipment, Part 2: Probes (EN ISO 18563-2:2017) was conducted. In addition, artificial crack detection images were simulated by the CIVA software, and an experiment under the same CIVA simulation conditions was also performed for comparison purposes. For the last verification, natural defective specimens with bolt-hole star-cracking, longitudinal vertical cracking and welding defects were scanned by the developed PAUSR, and its results were analyzed and compared with the radiographic testing (RT) and CIVA simulation outcomes.

The Influence of the Welding Process on the Ultrasonic Inspection of 9%Ni Steel Pipe Circumferential Welded Joints.

This work aims to compare the ultrasonic inspection of 9%Ni steel joints welded with the Gas Metal Arc Welding (GMAW) process and Shielded Metal Arc Welding (SMAW) process. These are the two most widely used processes used to weld pipes for CO2 injection units for floating production storage and offloading (FPSO) in the Brazilian oil and gas industry. The SMAW equipment is simple and portable, which is convenient for the FPSO; however, the GMAW process has the advantage of welding with high productivity. In this study we performed a numerical simulation using the software CIVA, 11th version, to analyze the behavior of ultrasonic longitudinal wave beams through GMAW and SMAW dissimilar weld joints. Ultrasonic tests were performed on calibration blocks drawn from both welded joints to evaluate the simulation results. The results are discussed with regard to the microstructure of the weld metal via electron backscatter diffraction (EBSD) analyses. The SMAW process presented better inspection performance than the GMAW process in terms of attenuation and dispersion effects. Although the SMAW had a better outcome, for both processes the configuration of 16 active elements and a scanning angle of 48° resulted in an optimized inspection of the entire joint.

2D Ultrasonic Antenna System for Imaging in Liquid Sodium.

Ultrasonic techniques are developed at CEA (French Alternative Energies and Nuclear Energy Commission) for in-service inspection of sodium-cooled reactors (SFRs). Among them, an ultrasound imaging system made up of two orthogonal antennas and originally based on an underwater imaging system is studied for long-distance vision in the liquid sodium of the reactor’s primary circuit. After a description of the imaging principle of this system, some results of a simulation study performed with the software CIVA in order to optimize the antenna parameters are presented. Then, experimental measurements carried out in a water tank illustrate the system capabilities. Finally, the limitations of the imaging performances and the ongoing search of solutions to address them are discussed.

Phased Array Ultrasonic Inspection of Metal Additive Manufacturing Parts

The adoption of wire and arc additive manufacturing (WAAM) in the market has been retained by the need to find a suitable method to ensure the quality of the parts produced. WAAM processes build up parts through the deposition of weld beads, consequently components with rough finish surfaces are characteristics of the method. Non-destructive testing (NDT) by ultrasonic (UT) method, namely the phased array technique (PAUT), is usually used to detect these defects in welding. However, the roughness of the parts represents a challenge for the UT application, since these variations influence the interaction between the emitted UT beam and the component. This study is thus focused on assessing the capability of detecting WAAM defects. The effectiveness of phased array ultrasonic testing to detect defects in aluminium WAAM components with several degrees of surface finish was evaluated. Simulations were first performed with CIVA software to characterize the beam emitted and select the probes and inspection parameters. Afterwards, physical inspections were performed on three reference specimens. Experimental outcomes prove that PAUT techniques are suitable for WAAM defects detection, including sizing, morphology and location. In addition, the experimental results were consistent with the simulated ones. The probes were able to overcome the limitations caused by the surface roughness of the samples, for a maximum of 89.6 μm average waviness profile. Also, defects ranging from 2 to 5 mm were characterized, in size and depth. These preliminary results represent an essential step for the development of an NDT system for inspecting WAAM parts.

Design and optimisation of a phased array transducer for ultrasonic inspection of large forged steel ingots

Large steel forgings are used in numerous industries. This paper investigates the possibility of adapting ultrasonic phased array testing to the inspection of forged steel blocks with dimensions of up to 1000 mm in every direction. The paper looks at two objectives in order to provide the best inspection performance: (1) the ultrasonic phased array probe optimisation and (2) the ultrasonic wave transmission sequence in a total focusing method imaging scenario. The CIVA software suite was used to optimise the phased array probe element count and width in a full matrix capture configuration. Based on the simulation results, a 32-element transducer was then built and tested in a 777 mm forged steel block using full matrix capture, plane wave and Hadamard transmission sequences. It was observed that plane wave and Hadamard sequences transmit significantly more energy inside the test sample because the elements are emitting simultaneously, therefore leading to an improved signal-to-noise ratio. However, the horizontal resolution was a strong limitation for every transmission sequence, especially for plane waves, because of the limited range of angles available in a block of large dimensions. The Hadamard transmission sequence was shown to represent the best compromise in terms of defect reflected amplitude, signal-to-noise ratio and resolution. The experimental results were compared with simulations and were found to be in very good agreement.