TY - CHAP A1 - Nonn, Aida A1 - Paredes, Marcelo A1 - Keim, Vincent A1 - Wierzbicki, Tomasz T1 - Comparison of Fracture Models to Quantify the Effects of Material Plasticity on the Ductile Fracture Propagation in Pipelines T2 - Proceedings of the 2018 12th International Pipeline Conference, Volume 3: Operations, Monitoring, and Maintenance, Materials and Joining, September 24-28, 2018, Calgary, Alberta, Canada N2 - Various numerical approaches have been developed in the last years aimed to simulate the ductile fracture propagation in pipelines transporting CO2 or natural gas. However, a reliable quantification of the influence of material plasticity on the fracture resistance is still missing. Therefore, more accurate description of the material plasticity on the ductile fracture propagation is required based on a suitable numerical methodology. In this study, different plasticity and fracture models are compared regarding the ductile fracture propagation in X100 pipeline steel with the objective to quantify the influence of plasticity parameters on the fracture resistance. The plastic behavior of the investigated material is considered by the quadratic yield surface in conjunction with a non-associated quadratic plastic flow potential. The strain hardening can be appropriately described by the mixed Swift-Voce law. The simulations of ductile fracture are conducted by an uncoupled, modified Mohr-Coulomb (MMC) and the micromechanically based Gurson-Tvergaard-Needleman (GTN) models. In contract to the original GTN model, the MMC model is capable of describing ductile failure over wide range of stress states. Thus, ductile fracture resistance can be estimated for various load and fracture scenarios. Both models are used for the simulation of fracture propagation in DWTT and 3D pressurized pipe sections. The results from the present work can serve as a basis for establishing the correlation between plasticity parameters and ductile fracture propagation. Y1 - 2018 U6 - https://doi.org/10.1115/IPC2018-78366 ER - TY - CHAP A1 - Nonn, Aida A1 - Erdelen-Peppler, Marion A1 - Wessel, Waldemar A1 - Harksen, Silke A1 - Mahn, Denise T1 - How to assure fracture-propagation control for seamless gas pipelines? T2 - Proceedings of the 2014 10th International Pipeline Conference (IPC2014), Volume 3: Operations, Monitoring, and Maintenance, Materials and Joining, September 29-October 3, 2014, Calgary, Canada N2 - Fracture propagation control in gas transmission gas pipelines belongs to the major design requirements for safe operation at high internal pressures. However, the current tests such as Drop-Weight-Tear Test (DWTT) and full-scale West-Jefferson (WJ) test reach the limits of their applicability with respect to transition temperature evaluation for seamless quenched and tempered small diameter pipes reflecting nowadays alloying concepts related to mechanical properties. Hereby, different geometry and material effects are evident which might lead to misinterpretation and unreliability of testing results. This paper aims to discuss open issues addressed in the literature and in own experimental findings with respect to reliability and transferability of testing methods, fracture parameters and their representativeness of seamless quenched and tempered pipeline behavior. By applying damage mechanics approach, it is possible to quantify the prevailing stress state and thus to understand the mechanisms controlling specific fracture appearance (ductile or brittle). Furthermore, studies were performed with objective to quantify the effect of different parameters (geometry, material and loading) on the fracture performance of the pipeline. The results from these investigations will serve as a basis for a safe pipeline design against propagating fracture. Y1 - 2014 U6 - https://doi.org/10.1115/IPC2014-33169 ER - TY - CHAP A1 - Nonn, Aida A1 - Paredes, Marcelo A1 - Nordhagen, H. O. A1 - Munkejord, S. T. A1 - Wierzbicki, Tomasz T1 - Challenges in fluid-structure modeling of crack propagation and arrest in modern steel pipelines T2 - 14th International Congress on Fracture (ICF14), 18-23 June 2017, Rhodes, Greece Y1 - 2017 SP - 1351 EP - 1352 ER - TY - CHAP A1 - Karbasian, H. A1 - Groß-Weege, J. A1 - Nonn, Aida A1 - Zimmermann, S. A1 - Kalwa, Christoph T1 - Assessment of collapse resistance of UOE pipes – comparison of full-scale and ring collapse tests T2 - Proceedings of the 10th International Pipeline Conference 2014 (IPC 2014), September 29 - October 3, 2014, Calgary, Alberta, Canada Y1 - 2014 ER - TY - CHAP A1 - Lang, Christian A1 - Steinborn, Florian A1 - Steffens, Oliver A1 - Lang, Elmar Wolfgang ED - Valenzuela, O. ED - Rojas, F. ED - Herrera, L.J. ED - Pomares, H. ED - Rojas, I. T1 - Applying a 1D-CNN Network to Electricity Load Forecasting T2 - Theory and Applications of Time Series Analysis N2 - This paper presents a convolutional neural network (CNN) which can be used for forecasting electricity load profiles 36 hours into the future. In contrast to well established CNN architectures, the input data is one-dimensional. A parameter scanning of network parameters is conducted in order to gain information about the influence of the kernel size, number of filters and number of nodes. Furthermore, different dropout methods are applied to the CNN and are evaluated. The results show that a good forecast quality can already be achieved with basic CNN architectures, the dropout improves the forecast. The method works not only for smooth sum loads of many hundred consumers, but also for the load of single apartment buildings. KW - Energy load forecasting KW - STLF KW - Neural networks KW - CNN KW - Convolutional networks Y1 - 2020 U6 - https://doi.org/10.1007/978-3-030-56219-9_14 SP - 205 EP - 218 PB - Springer ER - TY - CHAP A1 - Schneider, Ingo A1 - Nonn, Aida A1 - Völling, Alexander A1 - Mondry, A. A1 - Kalwa, Christoph T1 - A damage mechanics based evaluation of dynamic fracture resistance in gas pipelines T2 - Procedia Materials Science, Volume 3 N2 - Investigation of running ductile fracture in gas transmission pipelines and the derivation of reliable crack arrest prediction methods belong to major topics in pipeline research. The yet available crack arrest criterion, known as the Battelle Two-Curve Method (BTCM), leads to reliable predictions up to grade X70 line pipe steels for which it has been validated. This includes specific limits in terms of mechanical properties, pressure and geometry. The application of this criterion to modern pipeline steels, i.e. especially grades X80 and beyond in combination with larger diameters and high pressure, has led to mispredictions of the BTCM. Hence, in order to ensure safe design of pipelines, new methods are required based on in depth knowledge and appropriate characterization of material resistance. This paper presents a procedure for the assessment of dynamic ductile fracture resistance based on combined experimental and numerical investigations. The procedure involves quasi-static and dynamic drop- weight tear testing (DWTT) on modified specimens with pre-fatigued crack for grades X65, X80 and X100 materials, and the application of cohesive zone (CZ) and Gurson-Tveergard-Needleman (GTN) models to describe ductile material damage. The damage model parameters are calibrated on basis of DWTT results and subsequently used to simulate dynamic crack propagation in a pipeline. The influence of material properties (strain hardening, toughness), pipe geometry, usage factor and decompression behaviour on ductile fracture propagation behaviour is studied and evaluated. The results will contribute to an enhanced understanding of major parameters controlling ductile fracture propagation and will help to establish a reliable procedure for safe design of new high-capacity pipelines with regard to crack arrest. KW - Pipeline KW - Dynamic ductile fracture KW - Crack arrest KW - Cohesive zone model KW - DWT testing Y1 - 2014 U6 - https://doi.org/10.1016/j.mspro.2014.06.315 VL - 3 SP - 1956 EP - 1964 ER - TY - CHAP A1 - Kofiani, Kirki A1 - Nonn, Aida A1 - Wierzbicki, Tomasz A1 - Kalwa, Christoph A1 - Walters, Carey T1 - Experiments and fracture modeling of high-strength pipelines for high and low stress triaxiality T2 - 22nd International Society of Offshore and Polar Engineering 2012 (ISOPE 2012), Rhodes, Greece, June 2012 N2 - This paper provides results from a comprehensive study on mechanical characterization of high-strength pipeline steel, grade X100 using experimental and numerical methods. The material was characterized for anisotropic plasticity, fracture initiation for various states of stress, (pre-cracked) fracture toughness and uncracked ductility. The experimental program included tests on flat butterfly-shaped, central hole, notched and circular disk specimens for low stress triaxiality levels; as well as tests on round notched bar specimens and SENT fracture mechanics tests, for high values of stress triaxiality. This program covered a wide range of stress conditions and demonstrated its effect on the material resistance. Parallel to the experimental study, detailed numerical investigations were carried out to simulate all different experimental tests. Using an inverse method, a 3-parameter calibration was performed on the Modified Mohr-Coulomb (MMC) fracture model. Subsequently, the predictive capabilities of the MMC were evaluated by the comparison to the fracture toughness tests results, used extensively in the pipeline industry. The capabilities of the MIT fracture model have been demonstrated on an example of high strength offshore steel, X100. The outcome of this study was not only to provide, the overall characterization of the fracture behavior of this material as an example, but also to present the methodology on how to use the MMC model as a practical tool in pipeline design. Y1 - 2012 ER - TY - RPRT ED - Neuleitner, Nikolaus ED - Steffens, Oliver T1 - Energienutzungsplan für die Gemeinde Sinzing BT - Phase I. Bestandsaufnahme. Ergebnisbericht 1 (12/2011) Y1 - 2011 ER - TY - CHAP A1 - Zenger, Gerhard A1 - Kenner, Susanne A1 - Volbert, Klaus A1 - Waas, Thomas A1 - Kucera, Markus T1 - Acquiring energy data from a medium-voltage grid for future smart grid solutions: A practical smart grid application example realized by use of cellular communication networks of the 2nd and 3rd generation T2 - Proceedings of the 11th Workshop on Intelligent Solutions in Embedded Systems (WISES), 10-11 Sept. 2013, Pilsen, Czech Republic N2 - In this paper we present a practical example of the use of Cellular Communication standards like GPRS and UMTS in a Smart Grid Application. For a more detailed view we demonstrate a possible implementation of Cellular Communication Technologies in a data acquisition application for the collection of energy indicators in a medium-voltage grid. Furthermore, we show a technical overview of relevant and common mobile communication standards available in Germany. The included theoretical examples, Smart Grid scenarios, presented data and results are based on a research project for intelligent power regulation in medium-voltage grids performed in Regensburg (Germany). It is a joint project' of the University of Applied Sciences Regensburg together with a local energy provider and a manufacturer for distribution network systems. KW - Mobile communication KW - Medium voltage KW - Standards KW - Smart grids KW - Feeds KW - Ground penetrating radar Y1 - 2013 UR - https://ieeexplore.ieee.org/document/6664954 SN - 978-3-00-042899-9 SP - 1 EP - 8 PB - IEEE ER - TY - CHAP A1 - Kenner, Susanne A1 - Thaler, Raphael A1 - Kucera, Markus A1 - Volbert, Klaus A1 - Waas, Thomas T1 - Smart Grid architecture for monitoring and analyzing, including modbus and REST performance comparison T2 - International Workshop on Intelligent Solutions in Embedded Systems (WISES), 12th, 29.-30. Oct. 2015, Ancona, Italy N2 - Smart Grid, Smart Metering, Electromobility and the regulation of the power network are keywords of the transition in energy policies. In the future, the power grid will be smart. Due to this the OTH Regensburg does research in this area based on different projects. This paper presents a data collection, analyzing and monitoring software for a reference Smart Grid. We discuss two possible architectures for collecting data from energy analyzers. The performance is analyzed with respect to real-time monitoring, analyzing load peaks and automated regulation of the power grid. KW - Software KW - Computer architecture KW - Smart grids KW - Protocols KW - Databases KW - Servers KW - TCPIP Y1 - 2015 UR - https://ieeexplore.ieee.org/document/7356988 SN - 978-8-8875-4808-2 SP - 96 ER -