| 1. |
- Hammersberg, Peter, 1961, et al.
(författare)
-
EMULATION OF POD CURVES FROM SYNTHETIC DATA OF PHASED ARRAY ULTRASOUND TESTING
- 2012
-
Ingår i: AIP Conference Proceedings. - : AIP. - 1551-7616 .- 0094-243X. ; 1430:31, s. 937-944
-
Konferensbidrag (refereegranskat)abstract
- Reliability of non-destructive techniques (NDT) is traditionally quantified byexperimental determined probability of detection (POD). Such multi-parameter variability studies require a significant amount of experiments for each application verified, making them extremely costly. Reducing the need of experimental data by simulations requires both a verified simulation model and a procedure for effective computer experiments. Here synthetic POD curves for ultrasonic phased array testing have been generated using simSUNDT for signal amplitude simulations and a procedure to emulate response variability by predictive (meta) modeling and Monte Carlo simulations.
|
|
| 2. |
- Hammersberg, Peter, 1961, et al.
(författare)
-
The Potential in Simulation and Metamodeling for the Understanding and Development of NDE
- 2014
-
Ingår i: Materialpruefung/Materials Testing. - : Walter de Gruyter GmbH. - 0025-5300 .- 2195-8572. ; 56:11-12, s. 980-987
-
Tidskriftsartikel (refereegranskat)abstract
- By combining detailed mathematical modeling of the physics involved in NDE with a broader and robust engineering approach based on the sequential steps of screening, modeling and optimization, it is possible to generate metamodels that can support NDE engineering efforts to evaluate the applicability of NDE in a wider context, as a complement to the repeatability, reproducibility and capability studies normally performed. The aim of the initial screening phase is to effectively evaluate and prioritize NDE control parameters from a wider perspective regarding the demands of a specific application and to prioritize parameters of lesser importance for the outcome on the basis of economic and practical considerations. The aim of the second and third steps is to study the influence of the important parameters and to perform sensitivity analyses of reproducibility and repeatability, for example, followed by procedure development, respectively. The methodology is straightforward when it comes to smooth response surfaces of lower order (up to second or third order). Generally, the recommendation for the screening phase is 'to be bold' for the definition of the experimental range for each parameter - meaning to make them as wide as possibly relevant for the specific application. For NDE applications not following the Berens assumption for POD studies, e. g., large cracks yield large response signals, such as the varying signal amplitudes from surface breaking notches in ultrasonic testing, the mentioned recommendation of. be-bold. screening phase may lead to incorrect prioritization of parameters. In this publication, this is illustrated by how the width of the experimental range for the control parameters tested during screening actually influences the screening results. Two basic ultrasonic testing set-ups have been compared using the SimSUNDT simulation software package: surface breaking notch (SBN) and side drilled hole (SDH). Even though the results were anticipated, they pointed out the need to further develop the screening methodology supporting NDE engineering, especially when it comes to addressing the issue of applicability. Does the data collected tell us what we actually want to know about the tested application? Or does it only tell us something about the NDE method?
|
|
| 3. |
- Hammersberg, Peter, 1961, et al.
(författare)
-
The Potential in Simulations and Meta- Modelling for Understanding and Development of NDE
- 2013
-
Ingår i: 5th European-American Workshop on Reliability of NDE.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- By combining detailed mathematical modelling of the physics in NDE with a broader robust engineering approach based on the sequential steps: screening, modelling and optimization, it would be possible to generate meta-models that can support the NDE Engineering efforts to evaluate NDE applicability in a wider context, as a complement before the repeatability, reproducibility and capabilitystudies normally performed. The aim with the initial screening phase is to effectively evaluate and priorities NDE control parameters from a wider perspective relative the demand in the specific application and to fix parameters of less impact on the output response to their most economical and practical level. The aim with the second and third steps is to study how the important parameters influence and to perform sensitivity analysis of reproducibility and repeatability, for example,followed by procedure development, respectively. The methodology is straightforward when it comes to smooth response surfaces of lower order (up to second or third). The recommendation for the screening phase generally is ‘to be bold’ when it comes to the definition of the experimental range for each parameter – meaning make them as wide as possible relevant for the specific application. For NDE applications not following the Berens assumption for POD studies: large cracks yield large response signal. Such as, the varying signal amplitude from surface breaking notches in ultrasonic testing, for example. The be-bold-screening recommendation may lead to incorrect prioritization of parameters. In this paper this is illustrated by how the width of the experimental range for the control parameters tested during screening actually influence the screening result. Two basic ultrasonictesting set-ups have been compared using the SimSUNDT simulation software package: Surface Breaking Notch (SBN) and Side Drilled Hole (SDH). Even though the result was expected. It points out the need of development of the screening methodology supporting the NDE engineering, when it comes to addressing the applicability issue: does the data collected tell us what we actually want to knowabout the tested application (or does it only tell us something of the NDE method).
|
|
| 4. |
- Liu, Qingwei, 1970, et al.
(författare)
-
A Receiver Model for Ultrasonic Ray Tracing in an Inhomogeneous Anisotropic Weld
- 2014
-
Ingår i: Journal of Modern Physics. - : Scientific Research Publishing, Inc.. - 2153-120X .- 2153-1196. ; 5:13, s. 1186-1201
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, a receiver model for ultrasonic ray tracing simulation is described. This is a complementarypart of an existing simulation model and is the next step towards a numerical solutionto the inverse problem and thus a NDT methodology for characterization of the dendrite orientationin a weld. The establishment of the receiver model is based on the electromechanical reciprocityprinciple. A concise retrospect of the weld model and the 2D model is made. The reciprocityprinciple is applied in an original way to handle the model problem including the back wall.Experimental qualitative validations for both P and SV waves on a specific weld are also made forC-scans included in this paper. Two different cases are studied. The first is a direct incidence of anultrasonic ray towards the weld, and the second is a reflection from the back surface in the basematerial followed by an incidence to the weld. Even though mode-converted rays are excluded inthe simulations, both the P and SV probe-models show the same behavior as the experimental results.The qualitative validation though reveals that it even if a thorough time-gating of receivedinformation would enable exclusion of mode-conversion in the model, inaccuracy of experimentalresults is affecting the evaluation of the weld model.
|
|
| 5. |
- Persson, Gert, 1963, et al.
(författare)
-
POD GENERATED BY MONTE CARLO SIMULATION USING A META-MODEL BASED ON THE simSUNDT SOFTWARE
- 2012
-
Ingår i: AIP Conference Proceedings. - : AIP. - 1551-7616 .- 0094-243X. ; 2011:31, s. 1773-1780
-
Konferensbidrag (refereegranskat)abstract
- A recent developed numerical procedure for simulation of POD is used to identify the most influential parameters and test the effect of their interaction and variability with different statistical distributions. With a multi-parameter prediction model, based on the NDT simulation software simSUNDT, a qualified ultrasonic procedure of personnel within Swedish nuclear power plants is investigated. The stochastical computations are compared to experimentally based POD and conclusions are drawn for both fatigue and stress corrosion cracks.
|
|
| 6. |
- Persson, Gert, 1963, et al.
(författare)
-
Recent survey and application of the simSUNDT software
- 2010
-
Ingår i: AIP Conference Proceedings. - : AIP. - 1551-7616 .- 0094-243X. - 9780735407480 ; 1211, s. 2125-2132
-
Konferensbidrag (refereegranskat)abstract
- The simSUNDT software is based on a previous developed program (SUNDT). The latest version has been customized in order to generate realistic synthetic data (including a grain noise model), compatible with a number of off-line analysis software. The software consists of a Windows®-based preprocessor and postprocessor together with a mathematical kernel (UTDefect), dealing with the actual mathematical modeling. The model employs various integral transforms and integral equation and enables simulations of the entire ultrasonic testing situation. The model is completely three-dimensional though the simulated component is two-dimensional, bounded by the scanning surface and a planar back surface as an option. It is of great importance that inspection methods that are applied are proper validated and that their capability of detection of cracks and defects are quantified. In order to achieve this, statistical methods such as Probability of Detection (POD) often are applied, with the ambition to estimate the detectability as a function of defect size. Despite the fact that the proposed procedure with the utilization of test pieces is very expensive, it also tends to introduce a number of possible misalignments between the actual NDT situation that is to be performed and the proposed experimental simulation. The presentation will describe the developed model that will enable simulation of a phased array NDT inspection and the ambition to use this simulation software to generate POD information. The paper also includes the most recent developments of the model including some initial experimental validation of the phased array probe model. © 2010 American Institute of Physics.
|
|
| 7. |
|
|
| 8. |
|
|
| 9. |
- Rosell, Anders, 1981, et al.
(författare)
-
Estimating Probability of Detection Curves Related to Eddy Current Sender – Receiver Probes
- 2013
-
Ingår i: Proceedings of the 5th European-American Workshop on Reliability of NDE.
-
Konferensbidrag (refereegranskat)abstract
- Sender – receiver probes are commonly used in eddy current procedures for crack detection. Such probes can give a non-linear signal response as a function of the crack size. Classical methods used for analysis in probability of detection (POD) assessments require that the signal response versus crack size can be predicted with a linear relation, which also must show a constant variance of the collected data points. One approach which can be used to overcome these limitations is to use a mathematical model of the eddy current probe – flaw interaction and use this to estimate the detection probability at specific crack sizes. This method is applied within this work, using the finite element method for the eddy current signal response predictions. In order to manage a large number of calculations at several crack sizes we propose the use of a meta-model approach. A linear meta-model is created at different crack sizes and then used for POD estimation. The number of signal responses above the detection level at specific crack sizes is then used to estimate the POD, a method which does not require any particular relation between signal response and crack size. The meta-model enables a large number of stochastic computations to be carried out in order to estimate the signal response distribution for a specific crack size. We conclude that modelling is a vital part of procedure capability estimations of eddy current procedures based on sender – receiver probe characteristics and can be used for procedure understanding, improvements and aid in experimental verifications.
|
|
| 10. |
- Semenova, Maria, 1992, et al.
(författare)
-
Comparison between three mathematical models of three well defined ultrasonic NDT cases
- 2020
-
Ingår i: IOP Conference Series: Materials Science and Engineering. - 1757-8981 .- 1757-899X. ; 747:1
-
Konferensbidrag (refereegranskat)abstract
- Ultrasonic nondestructive testing (NDT) is commonly used for in-service inspection in different areas. But reliability of NDT method is highly dependent on the equipment and crack features. Although, it is possible to use thoroughly validated mathematical models to avoid complicated and costly experimental work, when it is necessary to qualify new procedures. Finite Element Model (FEM) is a powerful tool, which is commonly used for such cases. In this paper three mathematical models of three well defined cases will be compared with each other.
|
|
| 11. |
- Wirdelius, Håkan, 1963, et al.
(författare)
-
Simulation Based Validation of the Detection Capacity of an Ultrasonic Inspection Procedure
- 2012
-
Ingår i: International Journal of Fatigue. - : Elsevier BV. - 0142-1123. ; 41, s. 23-29
-
Tidskriftsartikel (refereegranskat)abstract
- With aging engines and structures, reliable maintenance will be a very important challenge in the future. This and other safety aspects have encouraged the development of non-destructive testing (NDT) technologies to detect in-service defects at an early stage. In order to quantify the inspection reliability the methodology of probability of detection (POD) was developed by the aeronautical industry in the early 1980s. This statistical tool reduces the number of artificially produced artefacts that needs to be introduced into the test blocks in order to get statistically valid information of the detection capacity, even though its legitimacy is limited to very restricted conditions. Even though this procedure reduces the number of defect it includes a large number of inspections and personnel and these campaigns thus tend to be time consuming and very expensive. This paper address the development of a procedure for generating POD based on synthetic data using NDT simulation software. The intention is to have an optimized experimental phase combined with much more efficiently retrieved simulated data. This has been achieved by fitting a multi-parameter prediction model to ultrasonic simulation software (simSUNDT) in an orthogonal design of experiments. The probabilities of detection as function of defect size (POD curves) at different defect depths were generated by Monte Carlo simulation introducing variations in the control factors with a physical interpretation in the emulator. The validation of this developed methodology has been based on a qualified ultrasonic procedure, UT-01. It specifies manual ultrasonic inspection of piping components within Swedish nuclear power plants and qualification of personnel according to this procedure has been in place since 1996. Experiences made by these qualifications were comprised as POD curves for both fatigue cracks and stress corrosion cracks in 2005. These POD curves are in this paper compared with corresponding generated with the above described simulation based methodology and the agreement found was remarkable well. © 2011 Elsevier Ltd. All rights reserved.
|
|
| 12. |
|
|
| 13. |
- Berg, Frenk van den, et al.
(författare)
-
Results of the European collaborative project "Product Uniformity Control" to improve the inline sensing of mechanical properties and microstructure of automotive steels
- 2018
-
Ingår i: e-Journal of Nondestructive Testing (eJNDT). - 1435-4934. ; 23:8
-
Tidskriftsartikel (refereegranskat)abstract
- A European consortium consisting of four major steel manufacturers and ten academic technology institutes has conducted a research and development project, called “Product Uniformity Control“ (PUC) in the period 2013 to 2017. This project aimed to develop and improve non-destructive (inline) measurement techniques to characterise the (uniformity of the) microstructure of steel strip products. In this project, a multitude of strip steel samples from various stages of production have been collected from the four participating steel manufacturers. The samples have been characterised in various ways, namely on their (1) non-destructive measurement parameters using different techniques suited for inline evaluation, (2) fundamental ultrasonic and electromagnetic properties (wave speed, ultrasonic attenuation, magnetisation loops, coercive field), (3) tensile properties (stress-strain curves) and (4) microstructure (by optical micrographs and EBSD images). The correlations between these different characterisations will be addressed. Besides the experimental characterisation, a strong accent has been on modelling activities: during the project, fundamental models have been developed to describe, starting from 2D and 3D microstructures, the ultrasonic and magnetic properties, which are next used as input to sensor models that predict the output of the inline measurement systems. This contribution presents the recent results of experimental work, which underlines the importance of associated modelling studies for the interpretation of the measurement data for the benefit of inline characterisation of the mechanical properties complementary to traditional destructive tensile testing.
|
|
| 14. |
|
|
| 15. |
- Boström, Anders E, 1951, et al.
(författare)
-
UTDefect: A simulation tool for ultrasonic NDT
- 1996
-
Ingår i: Proc. 14th Int. Conf. on NDE in the nuclear and pressure vessel industries.. - 0871705893 ; 1, s. 621-626
-
Konferensbidrag (refereegranskat)
|
|
| 16. |
- Chernikova, Dina, 1982, et al.
(författare)
-
Novel passive and active tungsten-based identifiers for maintaining the continuity of knowledge of spent nuclear fuel copper canisters
- 2015
-
Ingår i: Annals of Nuclear Energy. - : Elsevier BV. - 0306-4549 .- 1873-2100. ; 75, s. 219-227
-
Tidskriftsartikel (refereegranskat)abstract
- A new approach to provide a long-term safeguards identification of spent nuclear fuel containers, in particular copper canisters, is presented in this paper. The approach proposes the use of a tungsten insert marked with a binary code and placed inside the container. The insert is read with a combination of two independent techniques, radiation and ultrasonic measurements, in order to get a unique identification of the cask. Passive and active versions of the tag are considered. The passive version makes use of the radiation coming from the spent nuclear fuel itself. The active version of the tag is based on the use of an artificially introduced mixture of α-emitting isotopes, such as 241Am with materials, 11B and 23Na, which easily undergo α-induced reactions with emission of specific γ-lines, 2313 keV and 1809 keV, respectively. The paper discusses results of the radiation and ultrasonic measurements and Monte-Carlo evaluations as the first proof of the concept. The results of the investigations show the strong potential for this concept to maintain the continuity of knowledge of spent nuclear fuel copper canisters for a time scale up to a few thousands years without compromising the environmental safety of the casks.
|
|
| 17. |
- de Andrade Schwerz, Claudia, 1992, et al.
(författare)
-
In-situ detection of redeposited spatter and its influence on the formation of internal flaws in laser powder bed fusion
- 2021
-
Ingår i: Additive Manufacturing. - : Elsevier BV. - 2214-8604. ; 47
-
Tidskriftsartikel (refereegranskat)abstract
- The pervasive adoption of laser powder bed fusion (LPBF) as an industrial manufacturing technique relies on the improvement of its repeatability, currently limited by the stochastic formation of flaws. Considering that large flaws can form randomly and despite the optimization of process parameters, an in-situ monitoring technique suitable for detecting deviations that originate these critical flaws is paramount. The redeposition of spatters on the build area has previously been identified as one of the factors responsible for the rise of internal flaws, but so far limited are the efforts towards their detection. This study aims to detect spatter redeposits via in-situ monitoring and to couple the detections to lack of fusion. For that, long-exposure near-infrared in-situ monitoring associated with image analysis is employed to determine the exact locations and quantify the incidence of spatter redeposits across three full builds performed at varying layer thicknesses. The existence and distribution of internal flaws is verified ex-situ by means of ultrasonic inspection and metallography. The formation of internal flaws is attributed to spatter redeposits after detailed characterization of size, particle and surface morphology of spatter and identification of particles with identical characteristics on the fracture surface in the adjacencies of lack of fusion. It is found that spatters preferentially redeposit on the adjacencies of the gas outlet, but that the affected portion of the build area and the prevalence of detections is heavily dependent on the powder layer thickness employed in the manufacturing process. The monitoring system setup preferentially acquires signal from spatters redeposited on print regions, making it particularly suitable for flaw detection.
|
|
| 18. |
|
|
| 19. |
- Hammar, Lars, 1961, et al.
(författare)
-
Radiographic sensitivity improved by optimized high resolution X-ray detector design
- 2007
-
Ingår i: Proc. International Symposium on Digital industrial Radiology and Computed Tomography, June 25-27, 2007, Lyon, France.
-
Konferensbidrag (refereegranskat)abstract
- A compact imaging detector, based on scintillation fiber optics, has been used for highresolution industrial radiography since 1996. This type of imaging detectors have provento give superior performance compared to fine grained industrial x-ray film in terms ofdetection efficiency and spatial resolution.The objective of this paper is to show that the radiographic sensitivity can be improvedeven further.First, the detection process has been studied by Monte-Carlo simulations and the resultshows that the radiation is detected in a very narrow range from the axis of the primarybeam.Secondary, Monte-Carlo simulations shows that a bent fiber optic image conduit caneliminate radiation induced noise in the CCD almost completely and reduce the depth ofthe detector to less then 100 mm.
|
|
| 20. |
- Hammar, Lars, 1961, et al.
(författare)
-
Validation of a high resolution x-ray technique within the PARENT program
- 2014
-
Ingår i: Proceedings of the 10th International Conference on NDE in Relation to Structural Integrity for Nuclear and Pressurized Components. - 1831-9424. - 9789279367595 ; , s. 926-932
-
Konferensbidrag (refereegranskat)abstract
- The PARENT Round Robin Test (RRT) comprises a study of the efficiency of different nondestructiveexamination (NDE) techniques to detect and size stress corrosion (SCC) crack in Ni-basematerial. This report describes an x-ray technique that has been used for detection and characterizationof these defects.The x-ray source is a 450 kV x-ray machine and the detector is CCD-based with fiber optic lensand glass fiber optic scintillation screen. The imaging area of the detector is only 27 x 27 mm but thespatial resolution is very high. The un-sharpness in the image plane is measured to be less than 0.08mm.X-ray radiography is a volumetric method and to be able to detect cracks or parts of cracks theorientation has to be reasonably parallel with the x-ray beams. Therefor each defect is radiographed inseries of projections. The projection angle is from -10° to +10°, with increments of 2°. To determinethe size or the depth of the cracks a method are developed which describes the depth as function of themovement of the observed crack tip between the end positions in the series of exposures.
|
|
| 21. |
- Larsson, Lars, 1984, et al.
(författare)
-
Integral equation method for evaluation of eddy-current impedance of a tilted, surface-breaking crack
- 2013
-
Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 114:19
-
Tidskriftsartikel (refereegranskat)abstract
- An integral equation method for solving the eddy-current nondestructive evaluation problem for aflat, tilted, and surface-breaking crack in a conducting half-space is presented. The method involvesuse of a half-space Green’s tensor and the Bowler potential. This potential describes the jump in theelectric field over the crack and is expanded in basis functions related to the Chebyshev polynomials,being a more analytical approach than the commonly used boundary element method. In the method,the scatterer defines a transformation operator to be applied on the incoming field. This is practical insimulations of the eddy-current inspection where this operator is independent of the position of theprobe. The numerical calculations of the change in impedance due to the crack are compared to aFinite Element model of the problem and good agreement is found.
|
|
| 22. |
- Lei, Xiangyu, 1992, et al.
(författare)
-
Experimental Validation and Application of a Phased Array Ultrasonic Testing Model on Sound Field Optimization
- 2021
-
Ingår i: Journal of Modern Physics. - : Scientific Research Publishing, Inc.. - 2153-1196 .- 2153-120X. ; 12:4, s. 391-407
-
Tidskriftsartikel (refereegranskat)abstract
- In safety dominant industries, nondestructive evaluation (NDE) is crucial in quality assurance and assessment. Phased array ultrasonic testing (PAUT) as one of the NDE methods is more promising compared with conventional ultrasonic testing (UT) method in terms of inspection speed and flexibility. To incorporate PAUT, the techniques should be qualified, which traditionally is performed by extensive physical experiments. However, with the development of numerical models simulating UT method, it is expected to complement or partly replace the experiments with the intention to reduce costs and operational uncertainties. The models should be validated to ensure its consistency to reality. This validation work can be done by comparing the model with other validated models or corresponding experiments. The purpose of current work focuses on the experimental validation of a numerical model, simSUNDT, developed by the Chalmers University of Technology. Validation is conducted by comparing different data presentations (A-, B- and C-scan) from experimental and simulated results with some well-defined artificial defects. Satisfactory correlations can be observed from the comparisons. After the validation, sound field optimization work aiming at retrieving maximized echo amplitude on a certain defect can be started using the model. This also reveals the flexibility of parametric studies using simulation models.
|
|
| 23. |
- Lei, Xiangyu, 1992, et al.
(författare)
-
Experimental Validation of a Phased Array Probe Model in Ultrasonic Inspection
- 2020
-
Ingår i: Ultrasonics. - : Elsevier BV. - 0041-624X. ; 108
-
Tidskriftsartikel (refereegranskat)abstract
- New manufacturing technologies such as additive manufacturing facilitate flexible and complex designs and production of components. However, these new techniques should not compromise the safety aspect, which imposes higher demands on the integrity insurance and inspection methods. Phased array ultrasonic testing (PAUT) provides advanced inspection and evaluation processes, whereas qualification is still needed when applied together with new manufacturing techniques. Numerical modeling, as one of the potential qualification methods, has been developed for decades and should be validated before practical applications. This paper presents an experimental validation work of the phased array probe model implemented in a software, simSUNDT, by comparing the maximum echo amplitudes between the physical experiments and simulations. Two test specimens with side-drilled holes (SDHs) and different materials are considered for validation and practical purposes. An experimental platform with a mechanized gantry system, which enables stabilized inspection procedure, is built and applied during the validation work. Good correlations can be seen from the comparisons and this model is concluded as an acceptable alternative to the corresponding experimental work. The relation between depth and beam angle is also noticed and investigated, which is essential to guarantee an accurate inspection.
|
|
| 24. |
- Lei, Xiangyu, 1992, et al.
(författare)
-
Simulation-Based Investigation of a Probability of Detection (POD) Model Using Phased Array Ultrasonic Testing (PAUT) Technique
- 2022
-
Ingår i: Journal of Nondestructive Evaluation. - : Springer Science and Business Media LLC. - 1573-4862 .- 0195-9298. ; 41:2
-
Tidskriftsartikel (refereegranskat)abstract
- Probability of detection (POD) as a metric for quantifying the capability of inspection procedures in nondestructive evaluation (NDE), has been applied and evolved in industries since 1970s. Progress had been noted when certain statistical functions were brought up to model POD behavior, including log-normal model (also referred as Probit model). This model had been concluded to be the best fit and therefore has been widely used in many studies, while the involved assumptions and conditions were not carefully addressed and explored. To make flexible POD datasets available for specific inspection procedures and reduce the number of expensive experiments needed, model-assisted POD (MAPOD) is an alternative. This paper addresses a pure simulation-based POD procedure of an inspection scenario involving phased array ultrasonic testing (PAUT) on lack-of-fusion defects in additive manufactured (AM) components. The mathematical simulations are performed by an ultrasonic testing (UT) simulation software, simSUNDT, developed at Chalmers University of Technology in Sweden. Resulted inspection datasets with the proposed data processing steps are evaluated in terms of the assumptions and conditions of log-normal POD model, with the purpose of discussing the POD model validity under different circumstances. Simulation-based POD curves are finally compared with several discrete POD values at some defect sizes, calculated through massive computations from physics-model based metamodel. Comparisons and observations confirm satisfactory application of log-normal POD model despite some violations in model hypotheses.
|
|
| 25. |
- Lindgren, Erik, 1980, et al.
(författare)
-
Separation of geometrical- and defect information in digital radiographs using wavelet filter techniques
- 2011
-
Ingår i: ISABE 2011.
-
Konferensbidrag (refereegranskat)abstract
- This paper describes the development of a mathematical model of new digital x-ray technologies and is part of a project that intends to develop an automated system for structural integrity assessment. The first part of this paper explains the exploited attenuation model based on a ray tracing assumption with piecewise linear attenuation coefficients. This is followed by a description of how the modeled volume is defined by specification of simple mathematical surfaces and the third part specifies typical welds addressed in this project. The model of a digital x-ray detector and its implementation into a simulation tool is thereafter briefly described. A thorough validation of the x-ray attenuation and the simulation software using another software PENELOPE has been conducted. The paper is concluded with an example of intended approach to remove geometrical large scale information by applying wavelet transform of the radiograph.
|
|
| 26. |
- Lindgren, Erik, 1980, et al.
(författare)
-
X-ray modeling of realistic synthetic radiographs of thin titanium welds
- 2012
-
Ingår i: NDT and E International. - : Elsevier BV. - 0963-8695. ; 51, s. 111-119
-
Tidskriftsartikel (refereegranskat)abstract
- This paper describes the addition and benefits of an improved detector model and a radiographic noise model to a previously developed mathematical model of a specific radiographic system. The model intentions are to simulate realistic synthetic radiographs of thin laser welded titanium welds and to act as an X-ray projection kernel in an image analysis algorithm. Both these objectives put high demands on low calculation time and to accomplish this a number of simplifications have been done. An evaluation of the tradeoff when using the simplifications is essential and simulations of specific geometries and the radiographic inspection procedure are used for this purpose. As verification the simulated radiographs are compared to real digital radiographs relevant for the proposed applications.
|
|
| 27. |
- Liu, Qingwei, 1970, et al.
(författare)
-
A 2D model of ultrasonic wave propagation in an anisotropic weld
- 2006
-
Ingår i: NDT and E International. - : Elsevier BV. - 0963-8695. ; 40:3, s. 229-238
-
Tidskriftsartikel (refereegranskat)abstract
- In order to enable ultrasonic measurement of anisotropy and the directivity of dendrites in a weld, a forward formulation is presented in this paper. It describes a model of an anisotropic weld, a probe model defined by consistent boundary conditions, together with a 2D ray tracing algorithm. The capability of this developed model is illustrated in numerical examples. This hybrid model of the forward formulation will later be applied to solve the inverse problem. © 2006 Elsevier Ltd. All rights reserved.
|
|
| 28. |
- Liu, Qingwei, 1970, et al.
(författare)
-
Estimation of Grain Orientation in an Anisotropic Weld by Using a Model of Ultrasonic Propagation in an Inverse Scheme
- 2014
-
Ingår i: Modelling and Simulation in Engineering. - : Hindawi Limited. - 1687-5591 .- 1687-5605. ; 2014, s. 11-
-
Tidskriftsartikel (refereegranskat)abstract
- The initial step towards a nondestructive technique that estimates grain orientation in an anisotropic weld is presented in this paper. The purpose is to aid future forward simulations of ultrasonic NDT of this kind of weld to achieve a better result. A forward model that consists of a weld model, a transmitter model, a receiver model, and a 2D ray tracing algorithm is introduced. An inversion based on a multiobjective genetic algorithm is also presented. Experiments are conducted for both P and SV waves in order to collect enough data used in the inversion. Calculation is conducted to fulfill the estimation with both the synthetic data and the experimental data. Concluding remarks are presented at the end of the paper.
|
|
| 29. |
|
|
| 30. |
|
|
| 31. |
- Van Den Berg, F. D., et al.
(författare)
-
In-line Characterisation of Microstructure and Mechanical Properties in the Manufacturing of Steel Strip for the Purpose of Product Uniformity Control
- 2016
-
Ingår i: DGZfP-Proceedings BB 158. - 9783940283788
-
Konferensbidrag (refereegranskat)abstract
- The uniformity of the microstructure of steel strip over the entire coil length and between different coils of the same grade is key to stable and consistent material behaviour in steel manufacturers’ proprietary processes, like rolling and levelling, and customers’ processes, like pressing and deep-drawing. In particular for high-strength steels, like dual phase and complex phase steels, the microstructure is very sensitive to processing variations resulting in a potentially larger spread in the mechanical properties of the product. In July 2013, a large European consortium consisting of 15 institutes started an RFCS [1] – funded project called “Product Uniformity Control” (PUC) with the primary objective to achieve enhanced and sustained product uniformity of steel strip by improved interpretation of data from inline measurement methods that aim 2 for real-time and non-destructive characterisation of microstructure and technomechanical parameters. Commonly, these techniques are based on electromagnetic (EM) or ultrasonic (US) measurement principles, which are favoured because of their non-destructive and potentially contact-free nature. To improve the techniques for inline materials characterisation, the PUC consortium takes a systematic approach to investigate the interrelations between mechanical properties -- microstructural parameters -- EM & US properties -- inline measurement thereof. The studies involve dedicated laboratory experiments, modelling of the EM and US properties of steel, modelling of inline measurement setups and statistical analysis of data from inline measurement systems. The synthesis of these activities should result in improved, model-based, calibrations and finally in a broader deployment and integration of the inline material characterisation techniques in steel manufacturing, adding value to the product and enhancing the process efficiency throughout the production chain from hot-rolling to finishing. This paper outlines the project approach, highlights interconnecting modelling and experimental research work, and demonstrates first results. Various contributions being presented at this WCNDT conference originate from the collaborative activities of this PUC project.
|
|
| 32. |
- Van Den Berg, F. D., et al.
(författare)
-
Product uniformity control - A research collaboration of european steel industries to non-destructive evaluation of microstructure and mechanical properties
- 2018
-
Ingår i: Stud. Appl. Electromagn. Mech.. - : IOS Press. - 9781614998358 ; 43, s. 120-129
-
Konferensbidrag (refereegranskat)abstract
- In steel manufacturing, the conventional method to determine the mechanical properties and microstructure is by offline, destructive (lab-)characterisation of sample material that is typically taken from the head or the tail of the coil. Since coils can be up to 7 km long, the samples are not always representative for the main coil body. Also, the time delay (typically a few days) between the actual production and the availability of the characterisation results implies that these results cannot be exploited for real-time adaptation of the process settings. Information about the microstructure and material properties can also be obtained from electromagnetic (EM) and ultrasonic (US) parameters, which can be measured in real-time, non-destructively, and over the full length of the steel strip product. With the aim to improve the consistency in product quality by use of inline EM and US measurements, a European project called "Product Uniformity Control" (PUC) has been set up as a broad collaboration between 4 major European Steel Manufacturers and 10 Universities / Research institutes. Using both numerical simulations and experimental characterisations, we study the inline measured EM and US parameters in regard of the microstructural and mechanical properties. In this way, we aim to establish an improved understanding of their mutual relationships, and to apply this knowledge in existing and new nondestructive evaluation techniques. In this paper, the concerted approach of modelling and experimental validation will be addressed, and results of this work will be shown in combination with inline measured data.
|
|
| 33. |
- Volker, A., et al.
(författare)
-
Ultrasonic Assessment of Metal Microstructures, Modelling and Validation
- 2016
-
Ingår i: DGZfP-Proceedings BB 158, ISBN 978-3-940283-78-8. - 9783940283788
-
Konferensbidrag (refereegranskat)abstract
- The uniformity of strip rolled steel and its mechanical properties are intrinsically linked to the complex microstructure along the strip length. Ultrasonic methods are sensitive to differences in grain size, grain distribution and texture. This with the intention to provide suitable tools to inline monitors the properties of hot rolled steel. In this paper, we present a comparison of results from numerical and analytical simulations of the elastic wave propagation in deterministic and stochastic models of the microstructures. Modelled microstructures are used to provide the flexibility of assessing single microstructural parameters of different steel grades and rolling conditions. The individual simulations are validated against laser ultrasonic measurements on metal sheets in thickness range of 2mm-5mm, which were independently characterized metallurgically. The correlation to parameters as texture, grain size and dual phase composition was addressed. The simulation facilitates the development of methodologies to identify quantitative values that will enable to non-destructively assess the quality of a component. Different methods are developed based on changes in attenuation and velocity. These were tested against the simulated as well as the experimental data.
|
|
| 34. |
- Wirdelius, Håkan, 1963, et al.
(författare)
-
A model for ultrasonic NDE on defect detection
- 1995
-
Ingår i: Proc. 13th Int. Conf. on NDE in the nuclear and pressure vessel industries. - 0871705486 ; , s. 237-243
-
Konferensbidrag (refereegranskat)
|
|
| 35. |
- Wirdelius, Håkan, 1963
(författare)
-
An Optimization Technique for Inverse Crack Detection
- 2014
-
Ingår i: Journal of Modern Physics. - : Scientific Research Publishing, Inc.. - 2153-120X .- 2153-1196. ; 5:13, s. 1202-1222
-
Tidskriftsartikel (refereegranskat)abstract
- Any attempts to apply techniques that are based on indirect measurements of parameters that are believed to correlate to any material properties (or state) in an in-line situation must by necessity identify a mathematical model of this relationship. The most conventional approach is to use some empirically based model. If the analysis instead is based on an analytical model of a physical explanation, this trainee period can be minimized and the system is more dynamic and less sensitive to changes within the chain of production. A numerical solution to the inverse problem of ultrasonic crack detection is in this case investigated. This solution is achieved by applying optimization techniques to a realistic model of the ultrasonic defect detection situation. This model includes a general model of an ultrasonic contact probe working as transmitter and/or receiver and its interaction with the defect. The inverse problem is reduced to minimization of a nonlinear least squares problem and is performed with a quasi-Newton algorithm consisting of a locally convergent SVD-Newton method combined with a backtracking line search algorithm. The set of synthetic data the model is fitted with are generated both by numerical integration and with the two-dimensional stationary-phase method while the forward solver in the optimization procedure is based on the latter. In both these cases, the convergence, in terms of numbers of iterations, is sufficient when the initial guess is reasonably Close.
|
|
| 36. |
- Wirdelius, Håkan, 1963, et al.
(författare)
-
An ultrasonic methodology to non-destructively estimate the grain orientation in an anisotropic weld
- 2014
-
Ingår i: MATEC Web of Conferences. - : EDP Sciences. - 2261-236X. ; 12
-
Konferensbidrag (refereegranskat)abstract
- The initial step towards a non-destructive technique that estimates grain orientation in an anisotropic weld is presented in this paper. The purpose is to aid future forward simulations of ultrasonic NDT of this kind of weld to achieve a better result. A forward model that consists of a weld model, a transmitter model, a receiver model and a 2D ray tracing algorithm is introduced. An inversion based on a multi-objective genetic algorithm is also presented. Experiments are conducted for both P and SV waves in order to collect enough data used in the inversion. Calculation is conducted to fulfil the estimation with both the synthetic data and the experimental data. Concluding remarks are presented at the end of the paper. © Owned by the authors, published by EDP Sciences, 2014.
|
|
| 37. |
|
|
| 38. |
|
|
| 39. |
|
|
| 40. |
- Wirdelius, Håkan, 1963, et al.
(författare)
-
Integrity and quality assessment applied on laser welded titanium components
- 2014
-
Ingår i: MATEC Web of Conferences. - : EDP Sciences. - 2261-236X. ; 12
-
Konferensbidrag (refereegranskat)abstract
- Laser welding of thin titanium components, a critical component of many gas turbine engines, has demonstrated a tendency of generating pores in clusters with a prescribed orientation. These pores, also known as chain porosities, are often of harmless sizes (of 50-100 micrometer) as individuals. Though the cluster as such, depending on the distances and orientations in between the pores, may have an impact on the structural integrity. A recently developed algorithm for 3-D positioning of small pore defects in planar geometries using digital X-ray inspection aims at providing 3-D positions of the defects. This could then be used in-line to assess the welding quality in the manufacturing process. This presentation describes the development of a methodology that aims to incorporate non-destructive evaluation with, in this case, structural integrity. © Owned by the authors, published by EDP Sciences, 2014.
|
|
| 41. |
|
|
| 42. |
|
|
| 43. |
|
|
| 44. |
|
|
| 45. |
- Wirdelius, Håkan, 1963
(författare)
-
The implementation and validation of a phased array probe model into the simSUNDT software
- 2014
-
Ingår i: Proc. 11th Euro. Conf. on NDT, Prague 2014.
-
Konferensbidrag (refereegranskat)abstract
- Ultrasonic phased array technique has gone from being a unique technique with few and very specific purposes into being an established tool and replacing conventional contact technique in a broad field of applications. Even though the far-field behaviour is more or less identical to single crystal techniques the knowledge in e.g. how it differentiates in interaction with defects and geometry closer to the probe is rather limited. A thorough validated mathematical model based on the physics has the ability to overcome this lack of understanding and is the only realistic alternative in the development of new procedures based on this technique. The simSUNDT software consists of a Windows®-based preprocessor and postprocessor together with a mathematical kernel (UTDefect), dealing with the actual mathematical modelling. The model employs various integral transforms and integral equation and enables simulations of the entire ultrasonic testing situation. In the latest released version (2.0) a model of phased array probe has been incorporated. Each of its elements is in the model represented by the boundary conditions that generate a plane wave, at a certain angle, in the far field. These boundary conditions (i.e. the pressure on the surface under the element) are then translated into the main coordinate system and after superposition they built up a phased array wave front (constructive phase interference) with prescribed nominal angle. Modelling has been identified as an effective tool and in a previous work the developed methodology based on simulations of a well defined procedure was validated. In this paper a new model of phased array technique is implemented in the simSUNDT software and thoroughly validated.
|
|
| 46. |
|
|
| 47. |
|
|
| 48. |
- Wirdelius, Håkan, 1963
(författare)
-
Ultrasonic NDT in Defect Detection - Mathematical modelling
- 1995
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis is concerned with the mathematical modelling of the ultrasonic nondestructive testing situation. The first part of the thesis treats a simplified model of an ultrasonic transducer and its implementation into a T-matrix method-based solution to a crack scattering problem. The source is an acoustic piston-like model of an unangled compressional transducer acting in pulse echo situation with its behaviour as a receiver treated with reciprocity. The considered crack is a freely oriented penny-shaped crack-like flaw, partly closed due to an external background pressure. In order to evaluate and verify the numerical results, comparisons with numerical calculations, provided by a GTD method-based program package, are performed. The elastodynamic equivalence to the above is then considered. A more general probe model is proposed and modelled as boundary conditions on an elastic half-space. The action of the probe as a receiver is treated with a reciprocity argument. The electric signal is then obtained essentially as a product of the spherical expansion coefficients of the transmitting probe, the transition matrix of the defect and the spherical expansion coefficients of the receiving probe. The ultrasonic contact probe and its options as a transmitter are thoroughly investigated and several numerical examples are provided in the middle of the thesis. Numerically computed contour plots of the displacement field beneath the probe are given as snapshots, with varying contact conditions, frequency, bandwidth, angles and types. In order to enable experimental verification, a model for the ultrasonic probe evaluation situation, including the transmitting probe, an elastic plate and the receiving probe, has been developed. The reflection matrix representing reflection from the backwall is included and a model of the backwall measurement situation is deduced. Numerical examples are provided with varied couplants, shapes of effective area, traction distributions and different input signals. The final part of the thesis treats the ultrasonic inverse problem of determining the crack given the input and output electric signals. The numerical solution is achieved by applying optimisation techniques to the mathematical model of the ultrasonic NDT situation. The inverse problem is reduced to minimisation of a non-linear least squares problem and is performed with a quasi-Newton algorithm consisting of a locally convergent SVD-Newton method combined with a backtracking line search algorithm. Numerical examples for three specified realistic NDT situations are presented.
|
|
| 49. |
|
|
| 50. |
- Wirdelius, Håkan, 1963, et al.
(författare)
-
Validation of models for Laser Ultrasonic spectra as a function of the grain size in steel
- 2018
-
Ingår i: 12th European Conference on Non-Destructive Testing (ECNDT 2018). - 9789163962172
-
Konferensbidrag (refereegranskat)abstract
- To reduce costs of production and increase economic sustainability it is necessary to introduce quality assessment in an early stage in the manufacturing process. In an ongoing European project (Product Uniformity Control – PUC), the intention is to use ultrasonic information to assess microstructure parameters that are related to macroscale qualities such as mechanical properties. Laser induced ultrasonic technique (LUS) requires no media and can generate and detect ultrasonic information at some distance from the component. This technique is therefore addressed within this project as a solution to measure ultrasonic properties in an industrial environment. Mathematical modelling of the ultrasonic wave propagation problem has been used in order to get a deeper understanding of the physics and to identify ultrasonic properties that can be used as an indirect measurement of grain size. The use of both analytical and numerical models enabled extensive parametric studies together with investigation of ultrasonic interactions with well-defined individual microstructures. The LUS technique has previously been applied to e.g. monitor grain growth during thermomechanical processing of metals. These applications identified and used a correlation with the frequency content of the attenuation. This have been investigated as a possible indirect measurement of grain size, also in this project. The models have been used to verify the correlations and to evaluate different procedures that could be applied as an industrial solution. The suggested procedure is based on deconvolving two successive echoes and has been experimentally validated by two different LUS systems. The reference samples used in the validation were produced by changing the annealing temperature and time to obtain a variation in grain sizes. These grain sizes were then identified by EBSD and the samples were examined in terms of grain size influence on spectral attenuation
|
|
