TY - CONF A1 - Pavlovic, Mato A1 - Madia, Mauro T1 - The importance of determining the POD of the NDT system when designing a safe component N2 - Non-Destructive Testing (NDT) is routinely used in aerospace, nuclear, railway and automotive industries. The most common use of NDT is to find flaws in components. In dynamically loaded components, flaws grow, and if they are not detected in time and no corrective measures are taken they can reach critical sizes. When a flaw reaches a critical size, it endangers the structural integrity of the component and will likely cause the component to fail. To detect flaws before they reach a critical size, components are inspected in fixed time intervals with non-destructive testing systems. In order to determine the amount of time between inspections, three variables are necessary: the critical size of the flaw, the flaw propagation speed and the size of the flaw that can be reliably detected by NDT. All three variables are, to a certain extent, stochastic. The critical size of the flaw and flaw propagation speed are questions of fracture mechanics. The size of the flaw that can be reliably detected by NDT is predicted by POD curves. The POD is determined for a given inspection scenario. The inspection scenario includes the NDT system, the component geometry and the type of the flaw. If one of these changes, the POD will also change and needs to be recalculated. As a result, the design of a dynamically loaded safety-relevant components is an iterative process in which a geometry is sought that provides an optimum between structural integrity and inspectability. A model that describes the iterative process for the design of the safe components with examples from praxis will be presented. T2 - 15th ASIA PACIFIC CONFERENCE FOR NON-DESTRUCTIVE TESTING (APCNDT) CY - Singapore DA - 13.11.2017 KW - Safety KW - Mechanical design KW - Fracture mechanics KW - Nondestructive testing KW - POD PY - 2017 AN - OPUS4-43134 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 - Heckel, Thomas A1 - Zanotelli, Christina T1 - Determining probability of detection curves using experimental data and simulation N2 - Nondestructive testing (NDT) is routinely used in the nuclear, rail, aerospace and automotive industries to search for flaws in components. A signal from the flaw, recorded by the NDT device, will vary from measurement to measurement. The sources of this innate signal variation can be categorized into intrinsic, human and application factors. This variation, especially when searching for flaws that are at the limits of the NDT detection capabilities, can result in a failure to detect a flaw. If the inspected components are safety critical, the capability of NDT system to find flaws must be determined in order to avoid the catastrophic consequences of a missed flaw. The NDT system capability to detect flaws is expressed in terms of reliability. The probability of detection (POD) curve is a widespread tool to quantify the reliability of NDT. The POD is determined by series of experiments on specimens containing a range of flaws with known characteristics. The production of a sufficient number of these flaws is time consuming and expensive. In this paper, a multi-parameter POD model that uses both simulation and experimental measurements to calculate the POD curves will be presented. Simulation is used to assess the intrinsic capability of the NDT system and the variability in the system is estimated from experimental measurements. The POD calculated with the multi-parameter model is more comprehensive than the one calculated with the traditional model and the number of costly experiments needed is reduced. T2 - InnoTesting Conference 2017 CY - Wildau, Germany DA - 23.02.2017 KW - POD KW - Probability of detection KW - Reliability KW - Ultrasonics KW - Nuclear KW - Railway PY - 2017 AN - OPUS4-39280 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pavlovic, Mato A1 - Zoëga, Andreas A1 - Müller, Christina A1 - Kurz, J. H. A1 - Oelschlägel, T. A1 - Rohrschneider, A. A1 - Hintze, H. T1 - Investigations to Introduce the Probability of Detection Method for Ultrasonic Inspection of Hollow Axles at Deutsche Bahn N2 - Reliability investigation of the mechanised ultrasonic inspection system used to inspect hollow railway axles. T2 - ESIS TC24 Workshop "Integrity of Railway Structures" CY - Leoben, Austria DA - 24.10.2016 KW - POD KW - Ultrasonic KW - Reliability KW - NDT PY - 2016 AN - OPUS4-38460 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pavlovic, Mato A1 - Müller, Christina A1 - Heckel, Thomas A1 - Zoëga, Andreas A1 - Kurz, J.H. T1 - Using comprehensive probability of detection curves to support determination of inspection intervals of railway axles N2 - Deutsche Bahn periodically inspects hollow railway axles for fatigue cracks on the outer surface with mechanized ultrasonic inspection systems. According to the current standard for the inspection of railway axles, the capability of the inspection system to detect these cracks has to be demonstrated on the saw-cut type artificial defects. However, the geometry and the ultrasonic response of the real cracks that can occur on the outer surface of the axle are different from the saw-cut. Furthermore, it is demonstrated that the position and the orientation of the cracks are also important factors that influence the crack detectability. It is proposed to evaluate the influence of all factors on the detection of the cracks using the multi-parameter reliability model. The model uses numerical simulation and experiments to comprehensively address the influence of several factors on the probability of detection. T2 - 18th International Wheelset Congress CY - Chengdu, China DA - 07.11.2016 KW - Probability of detection KW - Ultrasonic inspection KW - Cracks KW - Hollow railway axles PY - 2016 AN - OPUS4-38280 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 - Pavlovic, Mato A1 - Müller, Christina A1 - Heckel, Thomas A1 - Zoëga, Andreas T1 - Reliability analysis of the ultrasonic inspection system for the inspection of hollow railway axles N2 - Axles are safety critical train components that are subjected to significant cyclic loading during operation. If the crack is initiated in the axle, cyclic loading will lead to crack propagation. To maintain structural integrity, axles must be periodically inspected for fatigue cracks in the material. Deutsche Bahn uses mechanized ultrasonic inspection system to inspect hollow railway axles. The inspections are performed from the bore surface, using several conventional transducers with different incident angles, inspecting the axle along the entire length. As with the every safety critical system, the reliability of these inspections must be determined with regard to their flaw detection capabilities. Traditionally this is done according to the relevant standards for railway vehicles. To investigate the capability of the NDT system more thoroughly, we want to evaluate the capability of the inspection system to detect flaws by means of probability of detection (POD) curves. It will be shown that other parameters, beside the size of the crack, for example crack position in the axle, influence the detection of the crack. The influence of these parameters was evaluated using ultrasonic simulation. The evaluation served as an input for the manufacturing of the flaws in the real scale axle. Once these axles are inspected and the data evaluated, using data from both measurement and simulation, we will express the POD of the crack as function of influencing parameters using the multiparameter POD model. T2 - Proceedings of the 19th World Conference on Nondestructive Testing CY - Munich, Germany DA - 13.06.2016 KW - Detection KW - Simulation KW - Ultrasonic KW - Railway KW - Reliability KW - POD KW - Crack PY - 2016 AN - OPUS4-36702 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pavlovic, Mato A1 - Müller, Christina A1 - Pitkänen, J. A1 - Ronneteg, U. T1 - Multi-Parameter Approach to Structural Integrity T2 - 9th International Conference on NDE in Relation to Structural Integrity for Nuclear and Pressurized Components T2 - 9th International Conference on NDE in Relation to Structural Integrity for Nuclear and Pressurized Components CY - Seattle, WA, USA DA - 2012-05-22 PY - 2012 AN - OPUS4-27006 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pavlovic, Mato A1 - Boehm, R. A1 - Müller, Christina A1 - Ronneteg, U. T1 - Evaluation of the Transmit Receive Longitudinal (TRL) Ultrasonic Inspection of the Nodular Cast Iron Insert for Permanent Storage of High-Level Radioactive Waste by Means of Probalbility of Detection T2 - ASNT Spring Research Symposium and Conference T2 - ASNT Spring Research Symposium and Conference CY - San Francisco, CA, USA DA - 2011-03-21 PY - 2011 AN - OPUS4-24590 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pavlovic, Mato A1 - Müller, Christina T1 - Ganzheitliche Zuverlässigkeit - POD der Prüfung von Bauteilen mit komplexer Geometrie T2 - DGZfP-Jahrestagung 2011 T2 - DGZfP-Jahrestagung 2011 CY - Bremen, Germany DA - 2011-05-30 PY - 2011 AN - OPUS4-24584 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -