Channel consistency calibration of planar eddy-current sensor arrays

Planar eddy-current sensor arrays have several advantages such as good coherence, fast response speed and high sensitivity, which can be used for defect inspection of crucial parts in mechanical equipments, and a key point to improve the detection performance is to ensure the channelconsistency of the planar eddy-current sensor arrays. The principle and characteristics of planar eddy-current sensor arrays are introduced in this paper, andthe channel consistency calibration algorithm is investigated based on least squares principle. An experimental system was established based on a field programmable gate array (FPGA) and ARM processor, which was utilized to inspect the defects in aluminum alloy. Based on this system, the channel data before and after calibration are analyzed, and the detection effect of three artificial defects is compared when the sensor channel calibration is implemented or not. The experimental results show that the sensor has excellent channel consistency and repeatability after calibration. The detection results of the three defects with size of 5 mm (length) x 0.1 mm(width) x 1 mm (depth), 7 mm (length) x 0.1 mm (width) x 1 mm (depth), 9 mm (length) x 0.1 mm (width) x 1 mm (depth) respectively show that the calibration algorithm has greatly improved the performance of the system.

Implementation of a robust methodology to obtain the Probability Of Detection (POD) curves in NDT: integration of human and environmental factors for Eddy Currents (EC)

In aeronautics, the evaluation of the Non-Destructive Testing (NDT) methods is a key step in the aircraft’s maintenance program. Nowadays, this calculation is performed by a statistical study taking into consideration the sources of uncertainty inherent in the applied NDT method. These uncertainties are due to human and environmental factors during In-Service maintenance tasks. The POD curve is carried out by an experimental process, where a wide range of inspector skills, defect types and locations, material types and procedures are included. At this moment, this experimental process evidences high costs and time consuming for the aircraft manufacturer.
The objective of this paper is to define a methodology of building POD from numerical modelling. The POD robustness is ensured by the integration of the uncertainties through statistical distributions issued from experimental data or engineering judgments. Applications are provided on titanium beta using High Frequency Eddy Currents (HFEC) NDT technique.
First, an experimental database will be created from three environments: laboratory, A321 and A400M aircrafts. A representative sample of operators, with different certification levels in NDT technique, will be employed. Multiple inspection scenarios will be carried out to analyse these human and environmental factors.
This database is used, subsequently, to build statistical distributions. These distributions are the input data of the simulation model. A POD module, based on the Monte Carlo method, is integrated to draw a sampling. This module will be applied to address human influences on POD. Additionally, this module will help us to state the device impact in POD curves.
Finally, the simulation POD model will be compared and validated with the experimental results. Numerical results encourage to replace or complete experimental campaigns in future works.

Numerical and experimental investigation of eddy current thermography technique on metallic samples

Current and future industry requirements demand advances in NDT. Fast and efficient methods and techniques for defect detection and characterization would be one of the main focus thus improving inspection results. Eddy current thermography is an emerging advanced NDT technique which combines the well-established eddy current testing with thermography inspection. It uses induced eddy current to heat the sample being inspected and defect detection is based on the changes of the induced eddy current flows revealed by thermal visualization over a relatively large area captured by an infrared camera. This work presents the results from 3D FEM simulation and experimental investigation of eddy current thermography on defects in metallic samples. The underlying phenomena of eddy current thermography testing are explored through the simulation which provides the explanation and reasoning of results. Experimental validation and investigation offers an insight to its potential for industrial application. The work demonstrates the effectiveness of eddy current thermography in providing comprehensive and reliable defect assessment.

Increased process safety and efficiently through Automated Defect Recognition (ADR) in X-ray inspection

Especially automotive manufacturers with a very high production volume demand interaction free in-line systems with Automated Defect Recognition (ADR). This reduces personnel costs and lowers the chance of human errors during the inspection process. Automated inspection systems have to comply to international quality standards like ASTM, VDI, EN etc. and the demanding company standards of VW, BMW, Porsche etc. As the production process of such parts is already completely automated systems have to be designed for 24/7 operation without human interaction, while offline stations are used to train the inspection sequences or review the results. This leads to a completely decoupled procedure for 100% system uptime.
Typical ADR applications are the detection of porosities, inclusions or cracks in casting parts. It is possible to define certain ROIs and check defect metrics like defect density, defect distance, defect size, defects per area and many more. Thresholds can be defined dynamically. Training of the system does not require any programming skills and can be done through local supervisors. This drives down production costs and reduces the inspection bottleneck, while increasing the reliability and process safety. An integration to Industry 4.0 factory solution allows full traceability of the inspection process on a part level.
More demanding tasks like automated measurement, completeness or density checks can be performed through the unique VAIP (VisiConsult Automated Image Processing) module. Complex test sequences can be performed on static images or in real time. Example applications: The behavior of heat pumps under different temperatures and completeness checks of valves.

Wireless 3D localization applied to the manual ultrasonic inspection of complex-geometry composite components.

An innovative method is described for obtaining high-quality and reliable ultrasonic C-Scan images during manual inspection. This method is based on visual tracking techniques and allows for inspection of components with complex geometry, avoiding the need for electro-mechanical devices, such as articulated arms or wire-encoders. Additionally, the most critical requirements for this method are described and compared with traditional inspection methods, in terms of productivity, ease of operation, performance and cost. This analysis is based on the operating experience and results obtained in aeronautical production environments.

Non-destructive inspection (NDI) of additive manufactured (AM) metal alloys

Additive manufactured (AM) metal alloys has enabled the fabrication of lightweight and high complexity components for the aerospace and automotive industry. Similar to traditional processing methods (e.g. casting, welding), porosity is a common concern in AM metal alloys.

X-Ray Computed Tomography (CT) scanning is the “ultimate” tool for porosity measurement in metal alloys. However, the equipment is costly, bulky and the data requires large storage size and long processing time. Therefore, there is a need to develop alternative non-destructive testing (NDT) techniques that are reliable yet less costly and impose lesser demand on post-measurement processing.

In this work, we reported the use of infrared thermography (IRT) and ultrasonic testing (UT) for porosity measurement of AM metal alloys. The samples-under-test are AM metal specimens with different degree of porosity. Consequently, we obtained the correlation between the IRT and UT results with respect to the degree of porosity. We believe that our method will be beneficial to researchers or engineers working on the NDI of AM metal alloys.

Detection of local stress concentration zones in engineering components – the lacking link in the NDT system

It is known that the main sources of damage during operation of engineering components are local stress concentration zones (SCZs) that are formed under the action of workloads primarily on defects of metallurgical and process nature. Sizes of these stress concentration zones vary from several tens of microns to several millimeters. Furthermore, it is unknown where these local areas are situated and how they can be detected. At the same time the reject norms of the applied NDT methods (ultrasonic testing, X-ray, MPI and other methods) at manufacturing plants significantly exceed the sizes of metallurgical defects.
At present a fundamentally new NDT method based on the use of the magnetic memory of metal (MMM) is more and more commonly applied in practice. It uses the natural magnetization formed during the components’ fabrication. The results are based on resent experiences.
The article considers the capabilities of the MMM method during the diagnostics of metallurgical and process manufacturing defects in new components.

Magnetic Estimation of Stresses in Welded Joint Zones with Different Initial Plastic Strains

During assembly or transportation to the site of assembly, as well as in operation, structural components may suffer additional uncontrollable plastic strain. This may change the initial level of informative test parameters.
In order to determine the capabilities of magnetic methods for the estimation of the stress-strain parameters of the material of individual zones of welded metal structures, in view of their his-tory, the effect of preliminary plastic strain on the magnetic behaviour of metal in different zones of a welded pipe under subsequent elastic tension/compression is studied.
Three groups of flat tensile test specimens cut out from the base metal, the weld and the heat-affected zone (HAZ) of a pipe made of the X70 steel are studied. In the first stage, the speci-mens were subjected to uniaxial tension to different values of plastic strain. In the second stage, the specimens plastically tensioned to different values were subjected to elastic tension/compression.
A correlation has been found between the magnetic characteristics of the metal in the differ-ent zones of the welded X70 steel pipe and the amount of plastic strain in these zones.
The magnetic behaviour of the base metal, the materials of the weld and the HAZ of a pipe has been determined as dependent on applied uniaxial tensile/compressive stresses, in view of the material history in the form of plastic strain to different degrees.
The magnetic characteristics of the materials are shown to vary uniquely in the range of ap-plied elastic uniaxial stresses between ‒200 and 120 MPa, and this makes them usable for the evalu-ation of the stress-strain state of the individual zones of welded X70 steel pipes.
The obtained results testify to the necessity of taking into account the initial SSS of metal structures when developing magnetic methods for the determination of their SSS parameters.

Modeling of 3D Electro-Mechanical Wave Propagation in 1-3 Piezocomposite based Ultrasonic Sensors: Simulation and Experimental Comparison

Quantitative modeling tools are important in design and fabrication of ultrasonic sensors with optimum characteristics and reduce the number of experimental efforts. This paper describes a computationally efficient 3D time-domain finite element modeling of electro-mechanical wave propagation in 1-3 piezocompoiste based ultrasonic sensors using the PZFlex software. First, we demonstrate the full 1-3 piezocomposite transducer design, which includes the standard dice-and-fill technique, electrical impedance matching layers, backing materials, electrical circuit of a coaxial cable and the coupling medium. The accuracy of electrical, mechanical and dielectric properties of a piezoceramic material are verified and optimized by comparing the simulated electrical impedance results with experiments, quantitatively. The acoustical properties of two-phase backing materials are analyzed to obtain the optimum volume fraction of heavy metal inclusions in the epoxy matrix. These acoustical properties are further incorporated in the transducer model to improve the accuracy of simulation results. The simulated ultrasonic pulse-echo results are compared with laboratory experiments and a good quantitative agreement is achieved. Finally, we discuss the applications of developed ultrasonic sensors in the Oil & Gas industry.

Replica Molding Technique – Quick and Accurate

In most industries where outage time is important short and accurate analysis time of surface anomalies and indications is essential. For these customers there is no time to deal with fake news.

The Replica Molding Technique (RMT) used by WesDyne has been developed to deliver fast and accurate surface measurements both submerged and in open air. The technique enables surface geometry measurements, profile measurements and defect detection with very high accuracy. RMT has been validated and qualified for detection of submerged 3µm wide and 1.5mm long surface breaking defects in the Swedish nuclear industry. Furthermore, RMT is suitable for and commonly used in combination with planned inspections for defect detection, in support of repair work (e.g. verification of boat sample cavities) and for wear measurements of submerged parts using 3D laser scanning and modelling of the retrieved replica. Unlike other surface techniques like dye penetrant, 3D laser scanning and eddy current techniques RMT is not affected by complex geometries, under water challenges or radiation levels.

One of the major benefits of RMT is the rapid preparation and deployment of equipment and NDE expertise saving significant critical outage time.