TY - CONF A1 - Stelzner, Ludwig A1 - Powierza, Bartosz A1 - Weise, Frank A1 - Oesch, Tyler A1 - Dlugosch, R. A1 - Meng, Birgit T1 - Analysis of moisture transport in unilateral-heated dense high-strength concrete T2 - Proceedings from the 5th International Workshop on Concrete Spalling N2 - Unilateral thermal exposure of concrete building components induces moisture transport processes that have a significant influence on the spalling behaviour of dense high-strength concrete (HSC). These transport processes are based on evaporation and condensation mechanisms of liquid and gaseous water in the pores as well as the chemically bound water within the concrete. The low permeability of HSC and the formation of a saturated zone within building components (also known as a moisture clog) leads to high water-vapour pressures, which contributes to explosive spalling. The formation of these pressures has already been verified by means of pore-pressure measurement techniques. In addition, the redistribution of the moisture within concrete specimens subject to unilateral thermal exposure has been demonstrated on fractured surfaces. Investigations by means of the nuclear magnetic resonance (NMR) relaxometry technique and neutron radiography have shown one-dimensional changes in moisture distribution during thermal exposure. However, none of these methods has been able to depict the moisture distribution in three dimensions (3D), so the link between pore size, concrete micro-structure and moisture content is missing. The research project presented in this paper aims to fill this gap by developing a new multi-level test methodology to characterise non-destructively the temporal course of spatial moisture distribution during unilateral thermal exposure. The procedure used during this programme included the collection of X-ray 3D-computed tomography (CT) measurements using a miniaturised specimen subjected to in-situ thermal exposure and the comparison of those CT results with the results of one-dimensional NMR-relaxometry before and after the heating process. In the first step, a mobile heating device was developed, built and tested. To simulate a unilaterally-heated construction component, a cylindrical specimen made of HSC (Ø = 40 mm, L = 100 mm) was cast into an impermeable glass ceramic shell. The ceramic shell ensured a one-dimensional moisture flux and limited the thermal expansion of the concrete. An additional high-temperature wool (HTW) insulating shell ensured a one-dimensional heat flux. The heating device, which operated using infrared radiation (IR), allowed the unilateral heating of the specimens up to 300 °C using variable heating regimes. In the second step, the mobile heating device was integrated into the CT-scanner, which enabled the collection of measurements before, during and after heating. By subtraction of successive 3D-CT images, X-ray attenuation differences could be resolved three-dimensionally in the specimen and interpreted as changes in the moisture content. Initial results show that this test methodology can monitor the 3D changes of moisture content inside the specimen during thermal exposure. It enables the researcher to visualise areas with moisture accumulation as well as dehydrated areas inside the specimen. Comparative one-dimensional NMR-relaxometry measurements confirm the results of the CT image analysis. T2 - 5th International Workshop on Concrete Spalling due to Fire Exposure CY - Boras, Sweden DA - 12.10.2017 KW - Spalling KW - Fire KW - Moisture clog KW - Moisture transport KW - HPC KW - HSC KW - X-ray CT KW - NMR KW - NDT PY - 2017 SN - 0284-5172 SP - 227 EP - 239 AN - OPUS4-42983 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Weise, Frank A1 - Stelzner, Ludwig A1 - Weinberger, J. A1 - Oesch, Tyler T1 - Influence of the pre-treatment of PP-fibres by means of electron irradiation on the spalling behaviour of High Strength Concrete T2 - Proceedings from the 5th International Workshop on Concrete Spalling N2 - It is known that the spalling risk of dense, high-strength concretes (HSC) can be reduced by the addition of polypropylene (PP) fibres and, in particular, PP-fibres that have been pre-treated using electron irradiation. It is presumed that the enhanced reduction in spalling resulting from electron irradiation pre-treatment of the fibres can be attributed to enhanced penetration of the molten fibre material into the micro-cracks around the fibres, due to their significantly decreased viscosity. So far there has been no experimental evidence for this. Against this background, this paper gives a com-parative analysis of the mode of action of PP-fibres with and without pre-treatment using multi-scale test methodology. Initially, fire tests on small-scale building components with accompanying damage monitoring veri-fied that the amount of PP-fibres can be halved by using pre-treated PP-fibres without reducing the fire performance of HSC. Detailed investigations of PP-fibres carried out in a completed research project funded by DFG (the German Research Foundation) using digital scanning calorimetry and thermogravimetry measurements (DSC/TG) as well as viscometer measurements showed that the pre-treatment has no significant influence on the melting temperature of the PP-fibres. However, a drastic reduction of the melt viscosity due to the electron irradiation was detectable. Additional dila-tation tests showed that the expansion behaviour of both fibre types and their melts do not differ significantly [1]. Rather, both fibre types generate high pressures when their thermal expansion is hindered. Further detailed investigations by means of continuous heating tests with a low heating rate were carried out on separately produced concrete cylinders. These tests showed that the pre-treatment of the PP-fibres causes earlier dehydration in conjunction with stagnation of thermal expansion of the concrete cylinders (temperature reduction from 180 °C to 170 °C). This is accompanied by in-creased acoustic emission activity during the thermal expansion tests. This leads to the assumption that the pre-treatment of PP-fibres results in earlier micro-crack development. However, it was not possible to confirm this assumption by microscopic examination of drilling cores with a diameter of 30 mm exposed to defined temperatures in the range between 150°C and 300°C. Microscopic obser-vations and additional X-ray 3D computed tomography (3D-CT) scans on miniaturised drilling cores exposed to temperature cycles showed a similar networking of fibre beds by means of micro-cracks in HSC for both fibre types. However, energy dispersive X-ray spectroscopy and wavelength disper-sive X-ray spectroscopy revealed fundamental differences in the penetration capacity of the fibre melts of the two fibre types. The increased penetration of the pre-treated PP-fibre melt revealed in these tests, confirms the initial working hypothesis. T2 - 5th International Workshop on Concrete Spalling due to Fire Exposure CY - Boras, Sweden DA - 12.10.2017 KW - Polypropylen fibres KW - Explosive spalling KW - HSC KW - HPC KW - Fibre melt KW - Penetration KW - Micro cracking KW - NDT PY - 2017 SN - 0284-5172 SP - 345 EP - 358 AN - OPUS4-42985 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pavlovic, Mato A1 - Gianneo, A. A1 - Kanzler, D. T1 - Achieving a more comprehensive POD using both simulation and measurements N2 - Today, it is an established fact that the capability of the non-destructive testing (NDT) to find flaws can be properly addressed only in terms of probability of detection (POD). The probabilistic, signal-response model, introduced in 1980s, was developed with experimental observation of eddy-current inspections of flat plate samples, containing surface breaking cracks. A linearity between the peak voltage measured by the testing system, and the crack depth was observed. The influence of the crack depth was therefore seen as the major influencing factor for the POD, whereas other factors merely caused the variability in the measurement. This model has proven itself valid for those inspection cases where there is only one main influencing factor on the POD (usually the flaw size) and other factors have a lesser influence. But with increasing requirements to quantify the capability of NDT systems in complex inspection situations, where several factors have a major influence on the POD, it has become clear that the applicability of this simple model has reached its limits. In disregard to its limitations, this model is regularly applied to those situations in which its fundamental assumptions are invalid, forcing evaluators and NDT researchers into attempts to fit the data to an unsuitable model, instead of fitting an appropriate model to the data. The multiparameter POD model, developed in the early 2010s, enables more factors that influence detection to be simultaneously analysed, making the POD a function of multiple factors. The model is based on the inspection’s physical model, to describe the influence of different factors on the response signal. Measurement variability is obtained from the experiment. Using this model assisted determination of the POD, the necessary number of flaws for evaluation is reduced and a more comprehensive understanding of the inspection is obtained. Several examples of the successful application of the multi-parameter POD model in different fields will be presented. T2 - 7th European-American Workshop on Reliability of NDE CY - Potsdam, Germany DA - 04.09.2017 KW - POD KW - Multi-parameter KW - Reliability KW - NDT PY - 2017 AN - OPUS4-42078 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pavlovic, Mato A1 - Müller, Christina A1 - Ronneteg, U. T1 - Reliability Analysis of the Phased-Array Ultrasonic System used for the Inspection of Friction Stir Welds T2 - Proceedings of the 19th Wolrd Conference on Nondestructive Testing N2 - The canister for the permanent storage of spent nuclear fuel used by SKB in Sweden consists of a cast iron insert surrounded by a five centimetre thick shell of copper. It is a safety critical component and in order to secure long-term structural integrity non-destructive methods are used to inspect 100% of the volume of each canister, before it is disposed of in the repository. One of the critical components that requires inspection is a sealing weld, joining the copper tube and the lid. The friction stir weld is inspected using an ultrasonic phased array system. The area of the weld is inspected with several inspection channels with different angles and varying coverage. To make sure that no defects that might occur in the weld are overseen, the reliability of the inspection must be quantified. The reliability of NDT is usually quantified with the probability of detection curves. The influence of the parameters that might influence the POD of the flaws in the weld is investigated analysing the experimental results, as well as with a help of a numerical simulation of the inspection. T2 - 19th Wolrd Conference on Nondestructive Testing CY - Munich, Germany DA - 13.06.2016 KW - NDT KW - Ultrasonic KW - Reliability KW - POD KW - Copper KW - FSW KW - JLH PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-366982 VL - 2016/158 SP - We.4.E.5 PB - Deutsche Gesellschaft für zerstörungsfreie Prüfung (DGZfP) CY - Berlin AN - OPUS4-36698 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pavlovic, Mato A1 - Müller, Christina A1 - Ronneteg, U. T1 - Reliability Analysis of the Phased-Array Ultrasonic System used for the Inspection of Friction Stir Welds of Copper Canisters N2 - The canister for the permanent storage of spent nuclear fuel used by SKB in Sweden consists of a cast iron insert surrounded by a five centimetre thick shell of copper. It is a safety critical component and in order to secure long-term structural integrity non-destructive methods are used to inspect 100% of the volume of each canister, before it is disposed of in the repository. One of the critical components that requires inspection is a sealing weld, joining the copper tube and the lid. The friction stir weld is inspected using an ultrasonic phased array system. The area of the weld is inspected with several inspection channels with different angles and varying coverage. To make sure that no defects that might occur in the weld are overseen, the reliability of the inspection must be quantified. The reliability of NDT is usually quantified with the probability of detection curves. The influence of the parameters that might influence the POD of the flaws in the weld is investigated analysing the experimental results, as well as with a help of a numerical simulation of the inspection. T2 - Proceedings of the 19th World Conference on Nondestructive Testing CY - Munich, Germany DA - 13.06.2016 KW - Ultrasonic KW - Copper KW - NDT KW - FSW KW - JLH KW - Weld KW - POD KW - Reliability PY - 2016 AN - OPUS4-36703 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Zoёga, Andreas A1 - Kurz, J. H. A1 - Oelschlägel, T. A1 - Rohrschneider, A. A1 - Müller, Christina A1 - Pavlovic, Mato A1 - Hintze, H. A1 - Kanzler, D. T1 - Investigations to introduce the probability of detection method for ultrasonic inspection of hollow axles at Deutsche Bahn T2 - Proceedings of the 19th World Conference on Non-Destructive Testing N2 - Currently at Deutsche Bahn (DB) ultrasonic inspections in maintenance procedures for wheelset axles with a bore hole are, to the greatest possible extent, carried out using automated ultrasonic inspection system. Although the acceptance levels are in accordance with DIN 27201 part 7, the testing results have shown in recent years that in the case of true indications, the effective defect sizes were far below the level of acceptance. Due to this experience it can be assumed that the automated ultrasonic inspection systems are testing substantially more sensitively than required. This increased sensitivity leads to an increase in false indications, generally resulting in the unnecessary demounting of wheelsets. In Research cooperation between Federal Institute for Materials Research and Testing (BAM) and DB the effective flaw detection sensitivity of existing automated ultrasonic inspection system will be determined and the true/false indication ratio optimised. Through systematic investigations with the Probability of Detection method on the existing automated ultrasonic inspection system the results could be directly applied to the optimisation of existing ultrasonic inspections of wheelset axles with a bore hole in maintenance procedures and the level of reliability can be considerably increased. T2 - 19th World Conference on Non-Destructive Testing CY - München, Germany DA - 13.06.2016 KW - NDT KW - Reliability KW - POD KW - Railway KW - Axles KW - UT PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-375813 UR - http://www.ndt.net/article/wcndt2016/papers/we2g4.pdf SP - id 19515, 1 EP - 8 AN - OPUS4-37581 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kanzler, D. A1 - Müller, Christina T1 - Probability of detection in nondestructive testing N2 - Motivation: What can we learn from the history of aerospace? State of the art: Detectability as the basis of probability of failure Evaluationmethods: Consequences of decisions based on ndt Advanced approaches: Probability of Detection: Evaluation of ndt systems are important! Use of the POD: Out of the box: Finnish and Swedish project for final disposal of spent nuclear fuel T2 - InnoTesting CY - Wildau, Germany DA - 25.02.2016 KW - NDT KW - Reliability KW - POD PY - 2016 AN - OPUS4-37586 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bertovic, Marija T1 - Automation in NDT: new risks and risk sources N2 - Reliability of NDT depends not only on the intrinsic capability of the measuring systems and on the application factors (the conditions under which NDT is applied), but also—and to a great extent—on human factors and the organisational context under which each inspection is carried out. Adoption of a systematic approach to the identification and prevention of risks. Critical defects could be missed, even if the inspection process is semi-automated. The causes of that risk lie in the technology, people and in the organisation. Currently installed preventive measures are insufficient to prevent from risks New preventive measures could be installed, e.g. further automation, installing alarms, implementing human redundancy, developing software and hardware solutions, optimising procedures, etc. Human factors studies are not only essential for the operation but also during the development process. T2 - 55th annual Conference of the British Institute for Non-Destructive Testing CY - Nottingham, UK DA - 12.09.2016 KW - NDT KW - Risk management KW - Reliability KW - Human factors PY - 2016 AN - OPUS4-37589 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bertovic, Marija T1 - Automation in non-destructive testing: new risks and risk sources T2 - BINDT: NDT 2016 Conference N2 - Over the past couple of decades Non-Destructive Testing (NDT) has seen a significant increase in the use of automation. In addition to increased reliability, objectivity, consistency, repeatability, productivity, and so on, automating parts of the process is expected to decrease the potential for human error. However, the literature on human-automation interaction suggests that automation is not only associated with benefits, but also with new risks and risk sources. First, this paper will present the methodology used to identify—for the first time—possible risks associated with mechanised data acquisition and corresponding data evaluation. Moreover, it will highlight possible risks, their causes, consequences, and ways of preventing them. Second, those preventive measures will be further analysed by examining new risks that can arise from their implementation, i.e. potential for failure that can arise from (a) working with automated defect-detection and sizing aids, (b) implementing human redundancy, and (c) improvement of the inspection procedures without due consideration of the procedure users. And third, some optimisations strategies will be provided. The purpose of this work is to show that mechanised testing is associated with potential for failure and that the sources of those risks go beyond single inspectors and need to be looked at in the interaction of people with other systems, i.e. the technology, the team and, most importantly, the organisation. T2 - 55th annual Conference of the British Institute for Non-Destructive Testing CY - Nottingham, UK DA - 12.09.2016 KW - NDT KW - Automation KW - Reliability PY - 2016 SP - 1 EP - 11 AN - OPUS4-37591 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kanzler, D. A1 - Müller, Christina T1 - How much information do we need? A reflection of the correct use of real defects in POD-evaluations JF - AIP Conference Proceedings N2 - To evaluate the capability of a non destructive testing system the “truth” of the used defects is essential. But what exactly is the truth of a real defect? And how much information is usable for the study? This presentation gives an overview about an advanced use of multiple metallographic cuts for the POD evaluation. In the presentation an approach is shown where information of metallographic studies are reconstructed and weighted to gain the essential information about real defects and which information are important for the detection with radiographic testing equipment. Furthermore, different connection points are discussed were additional knowledge from simulation and artificial defects can be used to gain additional certainty for the result of the evaluation. The methodology is used for the evaluation for the digital radiographic testing system for the testing of electron-beam welds, which is one possible choice to seal the Finnish copper canisters for the final deposit of spent nuclear fuel. T2 - 42nd annual review of progress in quantitative nondestructive evaluation: Incorporating the 6th European-American Workshop on Reliability of NDE CY - Minneapolis, MN, USA DA - 25.07.2015 KW - NDT KW - POD KW - Radiography PY - 2016 DO - https://doi.org/10.1063/1.4940652 SN - 0094-243X VL - 1706 SP - 200008-1 EP - 200008-7 PB - AIP Publishing AN - OPUS4-37596 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -