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 - CHAP A1 - Nonn, Aida A1 - Kalwa, Christoph T1 - Failure modeling of pipeline X100 Material in temperature transition region T2 - 22nd International Society of Offshore and Polar Engineering 2012 (ISOPE 2012), Rhodes, Greece N2 - This paper focuses on the characterization of the fracture performance of X100 material in transition temperature region using both experimental and numerical methods. The ductile fracture has been analyzed using tests on round notched bar specimens and standard fracture mechanics tests performed at room temperature. In previous publications the damage model Gurson-Tvergaard-Needleman (GTN) has been applied and verified by existing experimental data to describe ductile fracture behavior. The brittle fracture and the fracture in temperature transition region have been studied by means of deep and shallow notched SENB specimens at two different temperatures T=- 80°C and -40°C. Besides elastic-plastic analyses to quantify constraint levels for different initial crack configurations at the onset of cleavage fracture, the brittle failure has been described using modified Beremin model. The influence of the stable crack growth on the cleavage failure probability in temperature transition region has been captured by coupling the ductile fracture model (GTN) with the modified Beremin model. Finally, examples have been presented for the practical application of the numerical results on the fracture assessment of the flawed high-strength pipelines. Y1 - 2012 ER - TY - JOUR A1 - Ostermeier, Daniel A1 - Mottok, Jürgen A1 - Knorr, Christine A1 - Huber, Michael ED - Mottok, Jürgen ED - Ziemann, Olaf T1 - Competence Atlas for Save and Green Road Vehicles in the Electro Mobility Cluster Regensburg JF - Applied Research Conference 2012 (ARC 2012) 25./26. June 2012, Nuremberg Y1 - 2012 SP - 86 EP - 92 ER - TY - CHAP A1 - Mottok, Jürgen T1 - Migration path for secure and economic smart power grid devices with transitional smart metering support T2 - 2nd Applied Research Conference 2012 (ARC 2012), 25./26. June 2012, Nuremberg Y1 - 2012 SP - 64 EP - 70 ER - TY - CHAP A1 - Nick, Matthias A1 - Schorer, Michael A1 - Mottok, Jürgen ED - Mottok, Jürgen ED - Ziemann, Olaf T1 - Feasibility Study of a Build System Performing Automated Builds Based on Model-Based Build Descriptions T2 - 2nd Applied Research Conference 2012 (ARC 2012), 25./26. June 2012, Nuremberg Y1 - 2012 SP - 71 EP - 75 PB - Shaker CY - Aachen 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 - Bäuml, T. A1 - Haumer, Anton A1 - Kapeller, H. A1 - Starzinger, J. A1 - Farzi, P. T1 - Impact of inverter pulse inhibition on the high-voltage supply system of an electric vehicle — A simulative approach T2 - 2011 IEEE Vehicle Power and Propulsion Conference (VPPC 2011) : Powering sustainable transportation ; Chicago, Illinois, USA, 06. - 09.09.2011 N2 - This paper deals with a simulative approach for investigating the impact of inverter pulse inhibition during field weakening operation of permanent magnet synchronous machines and asynchronous induction machines. The modelling and simulation language Modelica is used to design models for the vehicle, the electric machine and the inverter in different abstraction levels. It is shown that when using a permanent magnet synchronous machine, a sudden breakdown of the field weakening current causes induction of high voltages in the stator windings. Hence, the electric system of the vehicle has to be protected against the resulting high currents. Furthermore precautions have to be taken to avoid dangerous driving conditions because of high braking torques in an inverter fault operation mode. In the case of the asynchronous induction machine an inverter pulse inhibition poses no big problem, neither for the electric system of the vehicle, nor the driver. KW - asynchronous machines KW - Connectors KW - electric vehicles KW - Inverters KW - invertors KW - Mathematical model KW - Object oriented modeling KW - permanent magnet machines KW - power engineering computing KW - Rotors KW - synchronous machines KW - Torque KW - Vehicles Y1 - 2011 SN - 978-1-61284-248-6 SN - 978-1-61284-247-9 SN - 978-1-61284-246-2 U6 - https://doi.org/10.1109/VPPC.2011.6043159 SP - 1 EP - 5 PB - IEEE CY - Piscataway, NJ ER - TY - CHAP A1 - Hong, Jongman A1 - Hyun, Doosoo A1 - Kang, Tae-june A1 - Lee, Sang Bin A1 - Kral, Christian A1 - Haumer, Anton T1 - Detection and classification of rotor demagnetization and eccentricity faults for PM synchronous motors T2 - 2011 IEEE Energy Conversion Congress and Exposition (ECCE 2011) : Energy conversion innovation for a clean energy future ; Phoenix, Arizona, USA, 17.-22.09.2011 N2 - Condition monitoring of rotor problems such as demagnetization and eccentricity in permanent magnet synchronous motors (PMSM) is essential for guaranteeing high motor performance, efficiency, and reliability. However, there are many limitations to the off-line and on-line methods currently used for PMSM rotor quality assessment. In this paper, an inverter-embedded technique for automated detection and classification of PMSM rotor faults is proposed as an alternative. The main concept is to use the inverter to perform a test whenever the motor is stopped, to detect rotor faults independent of operating conditions or load torque oscillations, which is not possible with motor current signature analysis (MCSA). The d-axis is excited with a dc+ac signal, and the variation in the inductance pattern due to the change in the degree of magnetic saturation caused by demagnetization or eccentricity is observed for fault detection. An experimental study on a 7.5kW PMSM verifies that demagnetization and eccentricity can be detected and classified independent of the load with high sensitivity. KW - AC Machine KW - Condition Monitoring KW - d-axis Inductance KW - Demagnetization KW - Eccentricity KW - fault diagnosis KW - invertors KW - Magnetic Saturation KW - Permanent Magnet (PM) KW - permanent magnet motors KW - Synchronous Motor (SM) KW - synchronous motors Y1 - 2011 SN - 978-1-4577-0542-7 SN - 978-1-4577-0541-0 SN - 978-1-4577-0540-3 U6 - https://doi.org/10.1109/ECCE.2011.6064103 SN - 2329-3721 SN - 2329-3748 SP - 2512 EP - 2519 PB - IEEE CY - Piscataway, NJ ER - TY - CHAP A1 - Hong, Jongman A1 - Lee, Sang Bin A1 - Kral, Christian A1 - Haumer, Anton T1 - Detection of airgap eccentricity for permanent magnet synchronous motors based on the d-axis inductance T2 - 8th IEEE International Symposium on Diagnostics for Electric Machines, Power Electronics & Drives (SDEMPED), 2011 // 05. - 08.09.2011, Bologna, Italy N2 - The majority of the work performed for detecting eccentricity faults for permanent magnet synchronous motors (PMSM) focus on motor current signature analysis (MCSA), as it provides continuous on-line monitoring with existing current sensors. However, MCSA cannot be applied under nonstationary conditions and cannot distinguish faults with load torque oscillations, which are limitations for many PMSM drive applications. In this paper, it is shown that the d-axis inductance, L d , decreases with increase in the severity of eccentricity due to the change in the degree of magnetic saturation, and it is proposed as a new fault indicator. The inverter can be used to perform a standstill test automatically whenever the motor is stopped, to measure L d for eccentricity testing independent of load variations or oscillations, which is not possible with MCSA. An FE and experimental study on a 10hp PMSM verifies that eccentricity can be detected independent of the load with high sensitivity and reliability. KW - Airgap Eccentricity KW - Condition Monitoring KW - Diagnostics KW - fault location KW - inductance KW - load (electric) KW - machine testing KW - Magnetic Saturation KW - Motor Current Signature Analysis (MCSA) KW - permanent magnet motors KW - Permanent Magnet Synchronous Motor KW - synchronous motor protection Y1 - 2011 SN - 978-1-4244-9301-2 SN - 978-1-4244-9303-6 U6 - https://doi.org/10.1109/DEMPED.2011.6063651 SP - 378 EP - 384 PB - IEEE CY - Piscataway, NJ ER - TY - CHAP A1 - Haumer, Anton A1 - Kral, Christian T1 - Modeling a Mains connected PWM Converter with Voltage-Oriented Control T2 - Proceedings of the 8th International Modelica Conference, Technical Univeristy, Dresden, Germany, 20.-22.03.2011 N2 - The majority of industrial controlled induction machine drives are connected to the mains via a diode bridge. However; if reduction of harmonic currents and / or regenerative operation is desired; replacing the diode bridge by an active front-end (AFE) is required. This paper describes two models of an AFE: a power balance model disregarding switching effects; and an ideal switching model of a pulse width modulation (PWM) converter. Both models are controlled utilizing space phasors in a voltage oriented reference frame. Voltage oriented control (VOC) of the mains converter can be compared with field oriented control (FOC) of a machine converter. Design and parametrization of the main parts—synchronization with mains voltage; current controller and DC voltage controller—are described in detail. Additionally; simulation results proving the implementation and demonstrating possible investigations as well as an outlook on further enhancements are presented. KW - Active Front-End KW - PWM Converter KW - Voltage-Oriented Control Y1 - 2011 U6 - https://doi.org/10.3384/ecp11063388 SP - 388 EP - 397 PB - Linköping University Electronic Press ER -