TY - JOUR A1 - Straub, D. A1 - Schneider, Ronald A1 - Bismut, E. A1 - Kim, H.-J. T1 - Reliability analysis of deteriorating structural systems N2 - Reliability analysis of deteriorating structural systems requires the solution of time-variant reliability problems. In the general case, both the capacity of and the loads on the structure vary with time. This analysis can be approached by approximation through a series of time-invariant reliability problems, which is a potentially effective strategy for cases where direct solutions of the time-variant reliability problem are challenging, e.g. for structural systems with many elements or arbitrary load processes. In this contribution, we thoroughly Review the formulation of the equivalent time-invariant reliability problems and extend this approximation to structures for which inspection and monitoring data is available. Thereafter, we present methods for efficiently evaluating the reliability over time. In particular, we propose the combination of sampling-based methods with a FORM (first-order reliability method) approximation of the series system reliability problem that arises in the computation of the lifetime reliability. The framework and algorithms are demonstrated on a set of numerical examples, which include the computation of the reliability conditional on inspection data. KW - Monitoring KW - Reliability KW - Deterioration KW - Structural systems KW - Bayesian analysis KW - Inspection PY - 2020 DO - https://doi.org/10.1016/j.strusafe.2019.101877 VL - 82 SP - Paper 101877, 1 PB - Elsevier Ltd. AN - OPUS4-48952 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dymkin, G. Y. A1 - Konshina, V. N. A1 - Jaenisch, Gerd-Rüdiger T1 - Оперативная характеристика обнаружения как метод оценки достоверности неразрушающего контроля T1 - Requirements for Accreditation Appraisal of NDT Laboratories in Nuclear Power Industry N2 - The operational characteristics of detection have been successfully applied for many years in assessing the reliability of non-destructive testing. The main problems for their use, as in the application of any of the methods for assessing the reliability, are the lack of information about the actual defect situation and the limited number of defects in the samples of the objects of control. An additional problem of constructing an operational characteristic of detection is the lack of information about the size of defects and the lack of a universal size for various types of defects. The article summarizes the experience of constructing operational characteristics based on the results of ultrasonic testing. N2 - Оперативные характеристики обнаружения в течение многих лет успешно применяют-ся при оценке достоверности неразрушающего контроля. Основными проблемами для их использования, как и при применении любого из методов оценки достоверности, яв-ляются отсутствие информации о действительной дефектной ситуации и ограниченное количество дефектов в образцах объектов контроля. Дополнительной проблемой постро-ения оперативной характеристики обнаружения является отсутствие информации о раз-мерах дефектов и отсутствие универсального размера для различных типов дефектов. В статье обобщён опыт построения оперативных характеристик по результатам ультра-звукового контроля. KW - Non-destructive testing KW - Reliability KW - Probability of detection KW - Operational characteristics KW - Comparative operational characteristics PY - 2021 DO - https://doi.org/https://doi.org/10.12737/1609-3178-2021-23-26 VL - 24 IS - 2 SP - 23 EP - 26 AN - OPUS4-53121 LA - rus AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Blankschän, M. A1 - Kanzler, D. A1 - Bertovic, Marija A1 - Rosenthal, Martina A1 - Liebich, R. T1 - Influence of illuminance on indication detectability during visual testing N2 - Visually detecting irregularities on components is a complex process, influenced by physical, technical, and human factors. Current standards mainly focus on illuminance, demanding highest accuracy for it, without providing scientific justification. In this research, 63 inspectors visually inspected forgings, with and without crack-like indications. The influence of illuminance on probability of detection was investigated. Therefore, illuminance was varied in three steps (200 lx, 350 lx, 500 lx). Human factors (e.g., experience, motivation) were recorded by using questionnaires. The results show no significant difference in probability of detection between the three illuminance levels. Equal probability of detection rates could be achieved at illuminances below and at the required threshold (500 lx). A difference in illuminance was found between the measurement point and the test area of the respective participant. This leads to higher assumed illuminance than present on the component. Compared with the measurement accuracy of the used illuminance meter, none of these deviations could be used to explain the similar results at different illuminance. The fact that illuminance has a significant influence in detecting indications has been disproven for this case. Whether human factors can provide explanation for the results remains unclear. This will be investigated in further research. KW - Illuminance KW - Non-destructive testing KW - Probability of detection KW - Reliability KW - Visual inspection PY - 2022 DO - https://doi.org/10.1515/mt-2022-0112 VL - 64 IS - 10 SP - 1532 EP - 1543 PB - De Gruyter AN - OPUS4-56019 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Küttenbaum, Stefan A1 - Kainz, C. A1 - Braml, T. ED - Matos, J.C. T1 - Non-destructively Measurable Quantities Relevant to Reliability Assessment of Existing Concrete Bridges – Case Studies N2 - In reliability assessment of existing bridges, collected information about the structure can be utilized to modify partial safety factors and to refine characteristic values individually. In this way, uncertainties covered in initial calculation models and arising from assumptions can be reduced as well as biases identified and corrected. This allows for more realistic assessments and more appropriate decisions on actions to be taken. However, the on-site observation of information is generally associated with certain costs. For this reason, an efficient data-supported reassessment requires that only the individually relevant testing tasks are solved. Additional sensitivity analyses can further be used to specify the requirements on certain inspections, such as the testing result quality to be achieved, in order to avoid too imprecise or too expensive measurements on-site. In this contribution, the methodology for the demand-actuated definition of measurement objectives is demonstrated using the example of non-destructive concrete testing methods and findings from reassessments of two prestressed concrete bridges. Each case study includes the semi-probabilistic identification of structural weak points in ultimate and serviceability limit states, a comparison with respective probabilistic sensitivity analyses, and the subsequent derivation of parameters that are a) measurable and b) highly relevant in the individual reliability analyses. KW - Reliability KW - Assessment KW - Existing structures KW - Non-destructive testing PY - 2024 SN - 978-3-031-60270-2 DO - https://doi.org/10.1007/978-3-031-60271-9_18 VL - 494 SP - 209 EP - 219 PB - Springer CY - Cham AN - OPUS4-60613 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Kainz, C. A1 - Braml, T. A1 - Keuser, M. A1 - Soukup, A. A1 - Küttenbaum, Stefan ED - Matos, J.C. T1 - Reassessment of Existing Concrete Bridges with Full Probabilistic Methods – Case Studies and Discussion of Relevant Input Parameters N2 - This article presents two case studies for a full-probabilistic assessment of existing concrete bridges combined with the use of the finite element method for the evaluation of the internal forces. Since the structures already exist, additional information about material parameters and loading conditions can be collected. With a sensitivity analysis, the contribution of each parameter to the total uncertainty is examined and the relevance of their actual value and variation is shown. The first case study is a single-span reinforced concrete frame bridge on the German highway A92 constructed in the year 1985. With a span of around 5 m, but a width of 27 m and a skewness of 70 gon, the bridge is modelled as a three-dimensional finite element model. The second case study is a two-span reinforced concrete frame bridge from 1986 with span lengths of about 7,50 m each. The superstructure is a 45 cm thick slab and the base plate has a thickness of 80 cm. The assessment is performed based on the semi-probabilistic safety concept according to the codes first and secondly with a full-probabilistic calculation. In this article the selection of parameters for the relevant input data are presented and discussed. The results of the sensitivity analysis are used for the setup of measurements to acquire important data for the modelling in the critical limit states. KW - Reliability KW - Assessment KW - Existing structures PY - 2024 SN - 978-3-031-60271-9 DO - https://doi.org/10.1007/978-3-031-60271-9_41 VL - 494 SP - 440 EP - 451 PB - Springer CY - Cham AN - OPUS4-60614 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schneider, M. A1 - Bettge, Dirk A1 - Hilgenberg, Kai A1 - Binder, M. A1 - Dollmeier, K. A1 - Dreyer, M. A1 - Klöden, B. A1 - Schlingmann, T. A1 - Schmidt, J. T1 - Reproducibility and Scattering in Additive Manufacturing: Results from a Round Robin on PBF-LB/M AlSi10Mg Alloy T1 - Reproduzierbarkeit und Streuung bei der additiven Fertigung: Ergebnisse eines Ringversuchs mit einer PBF-LB/M AlSi10Mg-Legierung N2 - The round robin test investigated the reliability users can expect for AlSi10Mg additive manufactured specimens by laser powder bed fusion through examining powder quality, process parameter, microstructure defects, strength and fatigue. Besides for one outlier, expected static material properties could be found. Optical microstructure inspection was beneficial to determine true porosity and porosity types to explain the occurring scatter in properties. Fractographic analyses reveal that the fatigue crack propagation starts at the rough as-built surface for all specimens. Statistical analysis of the scatter in fatigue using statistical derived safety factors concludes that at a stress of 36.87 MPa the fatigue limit of 107 cycles could be reached for all specimen with a survival probability of 99.999 %. N2 - Im Rahmen eines Ringversuchs wurde durch die Untersuchung der Pulverqualität, der Prozessparameter, der Gefügefehler, der Festigkeit und der Ermüdung die Zuverlässigkeit bestimmt, die Nutzer von AlSi10Mg-Proben erwarten können, die mit pulverbettbasiertes Schmelzen mittels Laser (engl. Laser Powder Bed Fusion) gefertigt worden sind. Abgesehen von einem Ausreißer wurden die erwarteten statischen Materialeigenschaften erreicht. Eine optische Gefügeprüfung diente dazu, die tatsächliche Porosität und Arten von Porosität zu ermitteln, um die bei den Eigenschaften auftretende Streuung zu erklären. Fraktographische Unterschungen zeigen eine bei allen Proben von der rauen Oberfläche im As-built-Zustand ausgehende Ermüdungsrissausbreitung. Aus der statistischen Analyse der Streuung bezüglich der Ermüdung unter Anwendung von statistischen abgeleiteten Sicherheitsfaktoren geht hervor, dass alle Proben die Dauerfestigkeit von 107 Zyklen bei einer Spannung von 36,87 MPa mit einer Überlebenswahrscheinlichkeit von 99,999 % erreichten. KW - Additive manufacturing KW - Reproducibility KW - Reliability PY - 2022 DO - https://doi.org/10.1515/pm-2022-1018 SN - 2195-8599 VL - 59 IS - 10 SP - 580 EP - 614 PB - De Gruyter AN - OPUS4-55935 LA - mul AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Würfl, J. A1 - Hilsenbeck, J. A1 - Nebauer, E. A1 - Tränkle, G. A1 - Obloh, H. A1 - Österle, Werner T1 - Reliability of AIGaN/GaN HFETs comprising refractory ohmic and Schottky contacts N2 - Recent progress in the development of A1GaN/GaN heterostructure field effect transistors (HFETs) Shows the great potential towards high temperature / high power electronics. Nevertheless investigations on reliability properties of GaN-based devices are still at the beginning. The frequently used Ti/A1 based ohmic and Pt based Schottky contacts suffer from strong Degradation after aging at elevated temperatures. Therefore new contact systems have to be employed. Concerning the source and drain metallization we used an amorphous WSiN barrier layer as applied for GaAs on top of the Ti/Al-based ohmic contact. This technique significantly reduces the in-diffusion of the Au-containing overlayer, furthermore the barrier layer guaranties smooth contact morphology after RTA and aging, respectively. For the Schottky metallization the Ir/Au system was used. Reliability studies performed on HFET devices containing refractory Ti/A1/Ti/Au/WSiN ohmic and Ir/Au Schottky contacts demonstrate stable conditions during 120h aging at 500°C. KW - Semiconductor KW - Reliability KW - Contact resistance KW - Heterostructure field effect transistor PY - 2000 SN - 0026-2714 VL - 40 SP - 1689 EP - 1693 PB - Elsevier AN - OPUS4-38541 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Müller, Christina A1 - Bertovic, Marija A1 - Kanzler, Daniel A1 - Ronneteg, U. T1 - Conclusions of the 6th European American workshop on reliability of NDE N2 - The principles of Open Space Technology (OST) were again applied to discuss burning issues in the field of NDE reliability. The results of the discussions among NDE professionals concerning new reliability methods, human factors and integrated solutions will be presented. T2 - 42nd Annual Review of Progress in Quantitative Nondestructive Evaluation CY - Minneapolis, Minnesota, USA DA - 26.07.20155 KW - NDT KW - Reliability KW - Probability of detection KW - Human factors KW - POD PY - 2016 SN - 978-0-7354-1353-5 DO - https://doi.org/10.1063/1.4940452 SN - 0094-243X VL - 1706 SP - 020006-1 EP - 020006-9 PB - AIP Publishing AN - OPUS4-36637 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Robens-Radermacher, Annika A1 - Unger, Jörg F. T1 - Efficient structural reliability analysis by using a PGD model in an adaptive importance sampling schema N2 - One of the most important goals in civil engineering is to guarantee the safety of the construction. Standards prescribe a required failure probability in the order of 10−4 to 10−6. Generally, it is not possible to compute the failure probability analytically. Therefore, many approximation methods have been developed to estimate the failure probability. Nevertheless, these methods still require a large number of evaluations of the investigated structure, usually finite element (FE) simulations, making full probabilistic design studies not feasible for relevant applications. The aim of this paper is to increase the efficiency of structural reliability analysis by means of reduced order models. The developed method paves the way for using full probabilistic approaches in industrial applications. In the proposed PGD reliability analysis, the solution of the structural computation is directly obtained from evaluating the PGD solution for a specific parameter set without computing a full FE simulation. Additionally, an adaptive importance sampling scheme is used to minimize the total number of required samples. The accuracy of the failure probability depends on the accuracy of the PGD model (mainly influenced on mesh discretization and mode truncation) as well as the number of samples in the sampling algorithm. Therefore, a general iterative PGD reliability procedure is developed to automatically verify the accuracy of the computed failure probability. It is based on a goal-oriented refinement of the PGD model around the adaptively approximated design point. The methodology is applied and evaluated for 1D and 2D examples. The computational savings compared to the method based on a FE model is shown and the influence of the accuracy of the PGD model on the failure probability is studied. KW - Reliability KW - Probability of failure KW - Adaptive importance sampling KW - Reduced order models KW - Proper Generalized Decomposition PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-510345 DO - https://doi.org/10.1186/s40323-020-00168-z VL - 7 SP - Article number: 29 PB - SpringerOpen AN - OPUS4-51034 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Küttenbaum, Stefan A1 - Maack, Stefan A1 - Taffe, A. A1 - Braml, T. ED - Sykora, M. ED - Lenner, R. ED - de Koker, N. T1 - On the Treatment of Measurement Uncertainty in Stochastic Modeling of Basic Variables N2 - The acquisition and appropriate processing of relevant information about the considered system remains a major challenge in assessment of existing structures. Both the values and the validity of computed results such as failure probabilities essentially depend on the quantity and quality of the incorporated knowledge. One source of information are onsite measurements of structural or material characteristics to be modeled as basic variables in reliability assessment. The explicit use of (quantitative) measurement results in assessment requires the quantification of the quality of the measured information, i.e., the uncertainty associated with the information acquisition and processing. This uncertainty can be referred to as measurement uncertainty. Another crucial aspect is to ensure the comparability of the measurement results.This contribution attempts to outline the necessity and the advantages of measurement uncertainty calculations in modeling of measurement data-based random variables to be included in reliability assessment. It is shown, how measured data representing time-invariant characteristics, in this case non-destructively measured inner geometrical dimensions, can be transferred into measurement results that are both comparable and quality-evaluated. The calculations are based on the rules provided in the guide to the expression of uncertainty in measurement (GUM). The GUM-framework is internationally accepted in metrology and can serve as starting point for the appropriate processing of measured data to be used in assessment. In conclusion, the effects of incorporating the non-destructively measured data into reliability analysis are presented using a prestressed concrete bridge as case-study. T2 - International Probabilistic Workshop 2022 (IPW2022) CY - Stellenbosch, South Africa DA - 09.09.2022 KW - Reliability KW - Assessment KW - Existing structures KW - Measurement uncertainty PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-556580 DO - https://doi.org/10.14311/APP.2022.36.0109 SN - 2336-5382 VL - 36 SP - 109 EP - 118 PB - Czech Technical University CY - Prague AN - OPUS4-55658 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -