bluuebunny/crossref_metadata_2025 huggingface dataset:
Calculation of S-N Curves for Different Mean Stresses on the Basis of “PHYBALmean” for the Quenched and Tempered Steel SAE 4140
Authors: Starke Peter , Eifler Dietmar
Published: December 2013

Recently, a couple of methods for the physically based fatigue life calculation of metallic materials were developed at the Institute of Materials Science and Engineering at the University of Kaiserslautern. The focus of these “PHYBAL”-methods is the reduction of the necessary experiments in comparison to the conventional determination of fatigue data. The application of the “PHYBAL”-method requires a limited number of high-precision fatigue experiments. In addition to conventional mechanical stress-strain hysteresis measurements temperature and electrical resistance measurements have to be carried out to characterize the cyclic deformation behaviour. So far the “PHYBAL”-versions “PHYBALW” (σW = endurance limit), “PHYBALLIT ” (LIT = load increase test), “PHYBALSB ” (SB = scatter bands) and “PHYBALmean ” (mean = mean stress) are available and were successfully applied on different unalloyed carbon steels as well as austenitic steels, cast irons and light alloy metals.
Prüfung linearer Bauteile auf Wälzfestigkeit
Authors: Karin Ivan , Hößbacher Johannes , Lipp Klaus , Hanselka Holger , Nommel Andreas
Published: December 2013

Kurzfassung

Die Untersuchung der Wälzfestigkeit linearer Bauteile, die durch ein neuartiges Kaltumformverfahren höhere Oberflächenhärten und geringere Rauigkeiten aufweisen, stellt prozessbedingt eine sehr große Herausforderung dar und erscheint in diesem Zusammenhang sinnvoll. Denn die momentan auf dem Markt befindlichen Prüfmethoden zur Wälzfestigkeitsermittlung basieren auf der rotationssymmetrischen Geometrie der Prüfkörper und stellen somit ein Ausschlusskriterium für lineare Bauteile dar. Um jedoch die spezifischen Eigenschaften, die aus dem Spaltprofilierprozess resultieren und die an die lineare Form der Spaltprofile gebunden sind, so real wie möglich simulieren zu können, wurde ein neuartiger Wälzfestigkeitsprüfstand für lineare Bauteile konstruiert, entwickelt und in Betrieb genommen. Mit diesem Prüfstand ist eine Bewertung der Wälzfestigkeit linearer Bauteile möglich.
Microstructure and Abrasion Wear Resistance of Thermally Sprayed Cermet Coatings
Authors: Utu Ion-Dragos , Hulka Iosif , Serban Viorel-Aurel
Published: December 2013

WC/10Co4Cr and WC/20CrC7Ni powders were sprayed onto the surface of low-carbon steel substrates using the high velocity oxygen fuel (HVOF) spraying method. Microstructure of the obtained coatings was evaluated by scanning electron microscopy (SEM). X-ray diffraction (XRD) analysis as well as hardness and porosity testing were performed on the samples. The abrasion wear resistance of the coatings was determined using the rubber wheel abrasion test. The mass loss rate (mg/h) of the samples was measured and the test results showed that the WC-CrC-Ni coating has better abrasion wear properties than the WC-CoCr coating.
Methods for Polymer Diagnostics for the Automotive Industry*
Authors: Grellmann Wolfgang , Langer Beate
Published: December 2013

The further development from polymer testing to polymer diagnostics leads to test methods with higher amount of information per test procedure as conventional tests. These changes contribute to fulfill the increased requirements in polymer testing and diagnostics. Selected examples of practice of industrial polymer testing show that these new methods can be applied appropriately to solve the issues of the automotive industry.
Empirical Correlation for Viscoelastic and Viscoplastic Behaviour of Rock Surfaces under Different Normal Stress Conditions
Authors: He Wubin , Wu Zhian , Guo Zhaoseng
Published: December 2013

This paper reports an improved constitutive model for the shear creep behaviour of offwhite marbles which are selected from slope or underground cavern and contain greenschist's weak structural planes. The shear creep behaviour of the samples is characterized by rheological tests. Based on the experimental measurements on mechanical properties under different normal stress conditions, an improved model is proposed to analyze the experimental results. It is demonstrated from a further discussion that such model can reflect the non-linear creep characteristics of structural planes, and especially, it is suitable for description of the viscoelastic and viscoplastic deformation behaviour of structural planes.
Study of p-6P Molecule Growth by In-Situ and Real-Time Spectroscopic Ellipsometry
Authors: Yan Zhi Dan , Sun Li Dong , Zeppenfeld P. , Hu Chunguang , Hu Xiao Tang
Published: December 2013

As an important analytical method for thin film growth, spectroscopic ellipsometry plays an active role in investigating thin film growth mechanism of molecular beam epitaxial especially under in-situ and real-time environment. In this paper, the dynamic data presenting p-6P molecule film growth on mica substrates at different evaporation temperatures have been obtained under ultra-high vacuum by a self-designed in-situ and real-time spectroscopic ellipsometry system. It is shown that the strength of p-6P molecular ellipsometry signal increases as the amount of molecule deposited increases, and there is a negative characteristic peak at 3.9 eV, caused by electron transition of the p-6P molecule from the highest occupied molecular orbital to the lowest unoccupied molecular orbital, which can be considered to be an optical characteristics of p-6P molecule.
X-Ray Radiography of Ti6Al4V Welded by Plasma Tungsten Arc (PTA) Welding
Authors: Dikbas Halil , Caligulu Ugur , Taskin Mustafa , Turkmen Mustafa
Published: December 2013

In this study, X-ray radiographic tests of Ti6Al4V alloys welded by plasma tungsten arc welding (PTA) were investigated. PTA welding experiments were carried out under argon shielding gas atmosphere, at 1400–1600 W and 1800 W welding powers as well as 1 m/min, 0.75 m/min, and 0.50 m/min welding speeds. After this process, radiography of the welded joints was performed by X-ray diffraction. The result of the radiographic tests indicated that by increasing welding power the widths of deep penetration increased in all specimens. On the contrary, increasing welding speeds decreases the widths deep penetration. The best properties of Ti6Al4V joints were observed for specimens welded at 1800 W welding power and at 0.50 m/min welding speed.
Fatigue Failure Assessment of Metallic Specimens Using the Acoustic Emission Technique
Authors: Mohammad Mazian , Abdullah Shahrum , Jamaludin Nordin , Innayatullah Othman , Nopiah Zulkifli Mohd
Published: December 2013

This paper presents a process to determine the relationship between acoustic emission (AE) signals and the strain signal pattern for estimating material fatigue life. In addition, it establishes the usefulness of AE in predicting the fatigue life of metallic components. This study was carried out to investigate the relationship between the strain and AE signals to ensure that AE can also be used as a tool to predict the fatigue life of metallic specimens. Two types of sensors, i. e., the AE piezoelectric transducer and the strain gauge, were attached to SAE 1045 steel specimens during the fatigue cyclic test when the specimens were under constant loading. Two types of signals were obtained at three different applied loads (6.0 kN, 6.4 kN and 6.8 kN). Both signal types were then analyzed using a statistical model, and the results were used to correlate the fatigue life and AE signals. The fatigue life values were calculated using strain-life models. The correlation between the experimental and predicted values of fatigue life was then established. The results showed that the correlation between the r.m.s. AE values and the calculated fatigue life ranged from 74.0 % to 98.5 %, while the correlation between the kurtosis AE values and the predicted values was found to be between 95.0 % and 99.9 %. These correlation values showed that the AE technique can be used to predict the fatigue life of metallic specimens.
3D-Schallfeldsteuerung mit Matrixarrays für die Pipelineprüfung
Authors: Schenk Gottfried , Brackrock Daniel , Boehm Rainer , Willems Herbert
Published: December 2013

Die Gefährdung durch Pipelines ist in der Öffentlichkeit wegen zahl­reicher Berichte über Unfälle weitgehend präsent. Warum? Weil jeder Unfall die Gefahr von massiven Umweltschäden mit sich bringt und bei Leitungen, die durch besiedeltes Gebiet führen, sogar mit menschlichen Opfern verbunden sein kann. Thema dieses Beitrags ist ein neuartiges Ultraschall-Verfahren, das eine schnellere, sichere und kostengünstigere Prüfung derartiger Rohrleitungssysteme erlaubt.
Optimization of Tensile Strength of Friction Welded AISI 1040 and AISI 304L Steels According to Statistics Analysis (ANOVA)
Authors: Ihsan Kirik , Ozdemir Niyazi , Firat Emrah Hanifi , Caligulu Ugur
Published: December 2013

Materials difficult to weld by fusion welding processes can be successfully welded by friction welding. The strength of the friction welded joints is extremely affected by process parameters (rotation speed, friction time, friction pressure, forging time, and forging pressure). In this study, statistical values of tensile strength were investigated in terms of rotation speed, friction time, and friction pressure on the strength behaviours of friction welded AISI 1040 and AISI 304L alloys. Then, the tensile test results were analyzed by analysis of variance (ANOVA) with a confidence level of 95 % to find out whether a statistically significant difference occurs. As a result of this study, the maximum tensile strength is very close, which that of AISI 1040 parent metal of 637 MPa to could be obtained for the joints fabricated under the welding conditions of rotation speed of 1700 rpm, friction pressure of 50 MPa, forging pressure of 100 MPa, friction time of 4 s, and forging time of 2 s. Rotation speed, friction time, and friction pressure on the friction welding of AISI 1040 and AISI 304L alloys were statistically significant regarding tensile strength test values.
Weldability of AISI 304 to Copper by Friction Welding
Authors: Kirik Ihsan , Balalan Zulkuf
Published: December 2013

Friction welding is a solid-state welding method, which can join different materials smoothly and is excessively used in manufacturing industry. Friction welding method is commonly used in welding applications of especially cylindrical components, pipes and materials with different properties, for which other welding methods remain incapable. AISI 304 stainless steel and a copper alloy of 99.6 % purity were used in this study. This couple was welded in the friction welding machine. After the welding process, samples were analyzed macroscopically and microscopically, and their microhardness was measured. Tensile test was used to determine the bond strength of materials that were joined using the friction welding method. At the end of the study, it was observed that AISI 304 stainless steel and copper could be welded smoothly using the friction welding method and the bond strength is close to the tensile strength of copper.
Bruchmechanisches Modell zur Ermittlung der Schwingfestigkeit von geschweißten und nichtgeschweißten Proben∗
Authors: Zerbst Uwe , Madia M. , Eufinger J. , Bruder Thomas
Published: December 2013

Ermüdungsrisse gehen in technischen Materialien in der Regel von Werkstoffdefekten auf oder nahe der Oberfläche aus. Bei Schweißverbindungen können Schweißnahtdefekte, z. B. oberflächennahe Schlackeneinschlüsse die Risseinleitungsphase erheblich verkürzen, so dass der Hauptteil der Lebensdauer auf die Phase der Kurzriss- und zu geringerem Anteil auf die Langrissausbreitung entfällt. Bei nichtgeschweißten Bauteilen aus technischen Werkstoffen starten Ermüdungsrisse häufig an Einschlüssen, oberflächennahen Poren oder anderen Ungänzen. Einerseits ermöglicht dies prinzipiell die Anwendung bruchmechanischer Methoden zur Ermittlung der Schwingfestigkeit, andererseits müssen die Methoden in der Lage sein, spezielle Aspekte des Kurzrisswachstums wie den graduellen Aufbau des Rissschließeffekts und die lokale Rissspitzenplastizität zu erfassen. Im Beitrag werden ein geeignetes analytisches Modell sowie erste Validierungen an Proben aus verschiedenen Aluminiumlegierungen vorgestellt. Der abschließende Teil des Beitrags geht auf Besonderheiten von Schweißverbindungen (Schweißnahtdefekte, Eigenspannungen etc.) im Kontext des vorgestellten Modells ein. Eine Erweiterung des Modells für Schweißverbindungen aus Stahl wird im Rahmen eines kürzlich gestarteten DFG-AiF-Clusterprojekts erfolgen.
Betriebsfeste Bemessung von Steckverbindern in Steuergeräten∗
Authors: Kimpel Thomas , Jauernig Udo , Becker Rolf , Wagener Rainer , Kaufmann Heinz , Sonsino Cetin Morris
Published: December 2013

Kurzfassung

Die Einpresstechnik ist eine kalte Kontaktiertechnologie und stellt eine Verbindung zwischen der Leiterplatte, die die Logikbauelemente trägt, und den äußeren Anschlüssen des Steuergeräts her. Die Hauptfunktion der Einpress verbindungen ist der Transport elektrischer Signale und Leistungen. Abhängig von der Konstruktion kann als weitere Funktion die mechanische Fixierung der Leiterplatte auftreten. Die Zuverlässigkeitsanforderung erfordert, dass die Funktionen über der Lebensdauer erhalten bleiben. Um die Funktionen unter zyklischer Belastung ermitteln und Veränderungen beobachten zu können, wurde ein Modellkörper für die Einpressverbindungen entwickelt. Weiterhin wurde ein geeigneter Prüfstand gebaut, mit dem die in der Fertigung und im Betrieb auftretenden Belastungen abgebildet wurden. Die Fehlerbilder der Einpressverbindungen und deren Schädigungsmechanismen, die durch zyklische Belastungen auftreten können, wurden am Modellkörper erarbeitet. Dabei war der Fokus auf die Kontaktzone gerichtet, die als Fügestelle zwischen Einpresspin und Leiterplattenhülse eine mögliche Schwachstelle darstellt. Es wurde gezeigt, dass der elektrische Übergangswiderstand der Kontaktzone durch vollflächige Reibkorrosion zu einem funktionalen Ausfall der Einpressverbindung führt. Eine Korrelation zwischen der mechanischen Festigkeit der Kontaktzone und dem Verhalten des Übergangswiderstands bei zyklischer Belastung wurde hergestellt. Dabei wurden die multiphysikalischen Eigenschaften der Fügestelle mit dem Ziel ausgenutzt, den Schädigungsmechanismus der vollflächigen Reibkorrosion über der Lebensdauer zu vermeiden. Eine geeignete Prüfmethode zur experimentellen Ermittlung der dreidimensionalen Belastbarkeit wurde entwickelt.
Betriebsfestigkeitsbewertung von Leichtbauklebeverbindungen–Herausforderungen bei Faserverbund- und Hybridbauteilen∗
Authors: Oppermann Helge , Metschkoll Matthias , Becker Ingo , Fröschl Jürgen
Published: December 2013

Kurzfassung

Der zunehmende Anteil an Faserverbundbauteilen in Karosseriestrukturen macht den Einsatz neuartiger Fügeverfahren zwischen Stahl und Faserverbundwerkstoffen erforderlich. Auf Grund der lokalen hohen Auslastung sind für diese Leichtbaufügeverfahren qualifizierte Betriebsfestigkeitsnachweismethoden notwendig. Der vorliegende Beitrag stellt die aktuellen Ergebnisse eines laufenden Methodenprojektes für die Betriebsfestigkeitsbewertung von Leichtbauklebeverbindungen vor. Nach einer Schilderung des Standes der Technik werden anhand von Versuchsergebnissen die unterschiedlichen Einflüsse wie Belastungsart, Umgebungs-temperatur etc. auf die zyklischen und statischen Festigkeitseigenschaften aufgezeigt sowie die Haupteinflussgrößen identifiziert. In einem zweiten Schritt werden die Vor- und Nachteile unterschiedlicher Betriebsfestigkeitsbewertungsmethoden solcher Klebeverbindungen anhand der Versuchsergebnisse identifiziert. Im Ausblick werden geplante Versuche an bauteilnahen Prüfkörpern zur Modellvalidierung vorgestellt sowie die bislang gewonnenen Erkenntnisse zusammengefasst.
Utilization of Power Plant Bottom-Ash Particles as Stabilizer in Aluminum Foams
Authors: Asavavisithchai Seksak , Prapajaraswong Attanadol
Published: December 2013

Aluminum foams, produced via powder metallurgical (PM) process, normally require the addition of ceramic particles in compaction stage, in order to increase both foamability of precursors and mechanical properties of the final foam products. Bottom ash particles are a by-product waste obtained from thermoelectric power plants which are commonly found to be used in landfill facilities. The major chemical constituent, approximately between 30 wt.-% and 60 wt.-%, of bottom ash particles is SiO2, depending on chemical composition in coal, sintering condition and environment, and other process parameters. In this study, we explore the feasibility of utilizing bottom ash particles of thermoelectric power plant wastes as stabilizer in aluminum foams. A small amount of two-size bottom ash particles (mean size of 78 µm and 186 µm), between 1 wt.-% and 5 wt.-%, have been added to aluminum foams. Foam expansion, macro- and microstructures as well as mechanical properties, such as compressive strength and microhardness, were investigated. The results from the present study suggest that bottom ash particles can be used as a stabilizing material which can improve both cellular structure and mechanical properties of aluminum foams.
Charakterisierung der Verformungsmechanismen bei hoch Mn-legierten Stählen unter einachsiger Zugbeanspruchung∗
Authors: Labudde Thorsten , Ingendahl Tobias , Wildau Maria , Saeed-Akbari Alireza , Hoffmann Sascha , Bleck Wolfgang
Published: December 2013

Kurzfassung

In hoch Mn-legierten Stählen treten in Abhängigkeit von der Stapelfehlerenergie (SFE) Verformungsmechanismen wie verformungsinduzierte Martensitbildung (TRIP), mechanische Zwillingsbildung (TWIP) und homogenes Versetzungsgleiten (SLIP) während der plastischen Umformung auf. Die SFE kann thermodynamisch berechnet und in sogenannten Mechanismenkarten grafisch dargestellt werden. Zur Beschreibung des Zusammenhangs zwischen Verfestigungsverhalten und Verformungsmechanismus im System Fe-Mn-C wurde zunächst die standardisierte Messtechnik im einachsigen Zugversuch mit zusätzlichen orts- und zeitauflösenden Verfahren kombiniert. Mittels Infrarot-Thermografie lässt sich das Auftreten von Dehnungsbändern infolge dynamischer Reckalterung detektieren. Der Einsatz lokaler Dehnungsanalyse auf der Probenoberfläche ermöglicht die quantitative Analyse der lokal erreichbaren Dehnung. In den sog. TORNADO-Diagrammen wird das Auftreten charakteristischer Muster in der Entwicklung der momentanen Dehnrate über der wahren Spannung zur Bestimmung der dominierenden Verformungsmechanismen genutzt. Die Oberflächentopografieänderung infolge Martensit- und Zwillingsbildung sowie prozessbedingter Einflüsse wie der Textur wurde mittels Konfokalmikroskopie untersucht.
Charakterisierung und Modellierung von Stahl-Klebverbindungen unter crashartiger Belastung∗
Authors: Böhme Wolfgang , Lienhard Jörg , Memhard Dieter
Published: December 2013

Kurzfassung

Zur Charakterisierung und Modellierung des Verformungs- und Versagensverhaltens von Stahl-Klebverbindungen des Klebstoffs Betamate 1496V wurden Hochgeschwindigkeitsversuche mit Rohrzug-, Scherzug- und 45°-Schrägzug-Proben bei crashrelevanten Dehn-/Scherraten bis zu 104 s−1 durchgeführt. Die Verformung der Klebschichten bis Bruch wurde optisch mit Hochgeschwindigkeitsvideokameras erfasst und mit Grauwertkorrelationsanalyse ausgewertet. Die ermittelten Spannungs-Dehnungskurven zeigen mit zunehmender Dehnrate einen deutlichen Festigkeitsanstieg und eine Abnahme der Bruchdehnungen. Die Scherspannungskurven liegen mit steigender Scherrate ebenfalls deutlich höher, verlaufen aber zunehmend flacher, während die Scherbruchdehnungen nahezu unverändert bleiben. Dies ist auf adiabatische Temperaturerhöhung zurückzuführen. Mit einem hierfür am Fraunhofer IWM erstellten Materialmodell zur Beschreibung des dehnratenabhängigen Klebstoffverhaltens wurden für die Hochgeschwindigkeitsscherversuche Temperaturerhöhungen der Klebschicht in einer Größenordnung von 50 K berechnet. Die Simulation wurde mit den Ergebnissen der 45°-Schrägzugversuche validiert.
Estimating the Lifetime of Fuel Cells by the Methods of Fatigue-Strength Analysis under Variable Stress Amplitude
Authors: Bonitz Saskia , Masendorf Rainer , Esderts Alfons
Published: December 2013

Estimating the fatigue life of metallic components has become an essential requirement in the industry because of the need to use light-weight constructions in conformance with stringent safety-relevant standards. However, the application of such methods for predicting the lifetime of electrochemical devices such as fuel cells is a novel approach. In this case, pertinent events and parameters, such as normal operation, open-circuit voltage, as well as starting and stopping processes, were extracted from the data determined from the measured current and voltage-time curve. For this purpose the classic counting methods, level-distribution counting and frequency counting are applied. The result thus obtained is assessed with the use of a damage parameter which describes the voltage drop as a function of time or of the number of cycles counted. Finally, the calculative estimation of the lifetime is determined by linear damage accumulation.
Analysis of Deposited Salts in the Through-Flow Area of a 210 MW Steam Turbine
Authors: Staniša Branko , Ćurković Lidija , Schauperl Zdravko
Published: December 2013

During the exploitation of a steam turbine, mainly because of non-adequate purity of fresh steam, salts can be deposited on the components in the through-flow area. Deposited salts decrease the reliability and efficiency of the steam turbine, while thicker layers, i. e. higher quantities of deposited salts, could cause serious damage to the turbine. This paper gives a description of deposited salt layers in the through-flow area of a 210 MW steam turbine and presents the results of research and analysis. In order to determine the cause of salt deposition on turbine surfaces, a chemical analysis of deposited layers was carried out. This paper proposes measures to reduce the salt deposition as well as methods for the removal of deposited layers in the through-flow area of a steam turbine.
Reinforcement of Steel Tubes with Rings under Compression
Authors: Açıkel Hicran , Kaltakcı Mevlüt Yaşar , Sönmez Ali
Published: December 2013

The goal of this study is to reinforce the compression strut ties of space truss systems by increasing the load carrying capacities of them. Therefore, 28 steel bar ties each having 900 mm length and 60.3 mm diameter were reinforced in six different ways and subjected to an axial compression test in the Structure Laboratory of the Civil Engineering department, Faculty of Engineering and Architecture, Selçuk University, Konya, Turkey. The results obtained from tests were examined by making comparisons between the plotted graphics. The applied reinforcement has not increased the buckling load, but it has increased the energy absorption capacity of reinforced bars under yielding and maximum stresses. When the negative effect due to welding is eliminated, a further increase in the energy absorption capacity at the yielding and proportionality limits and an increase in the maximum load carrying capacity can be expected.
Preparation of Hydroxyapatite Coating by Using Citric Acid Sodium Citrate Buffer System in the Biomimetic Procedure
Authors: Aydin Ibrahim , Cetinel Hakan , Pasinli Ahmet , Yuksel Mithat
Published: December 2013

The present study has been aimed to investigate the preparation and analysis of calcium phosphate (CaP) based hydroxyapatite (HA, Ca10(PO4)6(OH)2) coatings formed on Ti6Al4V alloys in a new buffer environment. The coating process has been performed by means of biomimetic method. In the study, a synthetic body fluid (SBF), which is fully compatible with human blood plasma, has been prepared for the first time in the literature by using the citric acid – sodium citrate buffer system. Using this buffer system will not cause any toxic reactions in the human body. CaP coating of the Ti6Al4V surface has been performed in this new SBF. The surface roughness and thickness specifications of the coatings have been determined, their microstructures have been analyzed by using a scanning electron microscope (SEM), the elemental analysis (EDX) of the coating surfaces and the XRD analysis have been done. The results are presented and discussed.
Comparison of ABC, CPSO, DE and GA Algorithms in FRF Based Structural Damage Identification
Authors: Gökdağ Hakan
Published: December 2013

In this contribution, performances of well-known population based algorithms, the artificial bee colony (ABC), contemporary particle swarm optimization (CPSO), genetic algorithm (GA), and differential evolution (DE) are compared in a basic model for damage identification (DI). DI is modeled as an inverse problem with the objective function based on the difference of the frequency response functions (FRF) computed by the finite element model of the structure and the reference data measured from damaged structure. Damage parameters are determined solving the problem with the aforementioned algorithms. It was observed that DE is the best one of a given number of function evaluations and gives the most accurate results in spite of noise interference to the reference data. According to the relevant literature, this is the first study including a comparison of these algorithms in an FRF based DI study.
Influence of Depth Alignment of E-Glass Fiber Reinforcements on Dental Base Polymer Flexural Strength
Authors: Vojvodić Denis , Kozak Dražan , Sertić Josip , Mehulić Ketij , Celebic Asja , Komar Dragutin
Published: December 2013

Fractures of denture base polymer material are one of the most frequent reasons for repair of removable dentures. The aim of this study was to determine the influence of depth alignment of glass fiber reinforcements onto denture base polymer flexural obtained with the “short beam” testing method. The study showed higher values of flexural strength when reinforcements were placed 1mm from specimen surface (130,63 to 158,55MPa) compared to 0,5mm distance from specimen surface (117,83 to 153,68MPa). Specimens tested after polymerization had higher flexural strength values than specimens tested after storage in water, while thermocycled specimens unexpectedly revealed the highest values. It could be concluded that fiber reinforcements should be positioned more than 0,5mm (up to 1mm) from the base surface of dental prostheses since lesser distance would diminish the reinforcing effect.
Sensitivity analysis of the Peach Bottom Turbine Trip 2 experiment
Authors: Bousbia-Salah A. , D'Auria F. , Bambara M.
Published: December 2013

The recent availability of powerful computer and computational techniques has enlarged the possibilities to perform best estimate simulations of complex scenarios in nuclear power plants. Nowadays, the coupled codes method, which consists in incorporating three-dimensional (3D) neutron modeling of the reactor core into system codes, is extensively used. It is particularly suited for simulating transients that involve core spatial asymmetric phenomena and strong feedback effects between core neutronics and reactor loop thermal-hydraulics. Within this framework the Peach Bottom BWR 2 Turbine Trip test was selected since it involves a rapid pressure induced positive reactivity addition into the core. It is also characterized by a self-limiting power course due to compensated inherent reactivity mechanisms. To perform a numerical simulation of the turbine trip a reference case was run for the coupled thermal-hydraulic system code RELAP5/mod3.3 and 3D neutron kinetic PARCS/2.3 code. The overall data comparison shows good agreements between the calculations and most of the significant global aspects observed experimentally. However, the test is very sensitive to the feedback modeling and requires a tightly accurate simulation of the thermal-hydraulic and the cross sections parameters. For this purpose, sensitivity studies have been carried out in order to identify the most influential parameters that govern the transient behavior. The considered cases showed that the self-limiting power amplitude as predicted by the coupled code calculation is mainly due to delayed feedback mechanisms whereas the experimental data shows that the power quenching before the Scram is governed by prompt feedback effects.
A new data-condensation method based on multidimensional minimisation
Authors: Lassmann K. , van de Laar J.
Published: December 2013

During irradiation in the Halden Reactor data such as linear rating, coolant temperature, or reactor state are routinely stored every 15 minutes, in the case of special events even at shorter time intervals. Because of the long irradiation times of up to several years, a huge amount of data is produced which is considered to be too much for direct input into fuel performance codes. In order to reduce the amount of data, various data-condensation procedures have been developed, which are briefly discussed. An innovative data-condensation method based on multidimensional minimisation is presented. The condensation factor obtained so far for Halden irradiations is 25–40, which is sufficient for a modern fuel rod performance code like TRANSURANUS. This new condensation method avoids all loss of experimental data and doubtful averaging of temperatures associated with other more drastic condensation methods. Up to now, the so-called reactor state variable, which defines the reactor operation (e. g. constant, decreasing or increasing power), has not been used. The introduction of this variable should further improve this new condensation method.
Improved Dancoff factors for cluster fuel bundles by the WIMSD code
Authors: Leite S. Q. Bogado , Zabadal J. R. S. , de Vilhena M. T.
Published: December 2013

The recently developed tracking routine PIJM, for computing improved two-dimensional first-flight collision matrices for the WIMSD code, has been modified to evaluate black Dancoff factors for cluster fuel bundles in unit cells with cylindrical outer boundaries. The routine, similar to the original PIJ but employing an efficient in-plane integration scheme of the Bickley functions appearing in those expressions, is first compared with the accurate Carlvik method in the calculation of Dancoff factors for regular lattices, both with and without a gap surrounding the fuel rods. Dancoff factors for the more general cases of CANDU37 and CANFLEX fuel bundles are next obtained and compared with Monte Carlo based calculations, illustrating the accuracy of the proposed scheme.
Steady state thermal-hydraulic analysis for the ETRR-2 Research Reactor
Authors: Abdelrazek I. D. , Khalil M. Y. , Shaat M. K. , Shokr A. M.
Published: December 2013

A steady state thermal-hydraulic analysis for the ETRR-2 Research Reactor has been performed using the computer code TERMIC. The analysis has included both, the verification of the core design as well as the performance of the equilibrium core. The uncertainties due to fuel fabrication tolerances, possible deviations in the operational measurements, the errors in the experimental correlations used in the analysis, and the errors due to simplifications made in the calculations have been considered in the analysis. A methodology based on uncertainties propagation has been adopted for the evaluation of hot channel factors. The results of the thermal-hydraulic analysis show that the reactor can be operated at full power level with sufficient safety margins against the thermal-hydraulic critical phenomena.
Analysis on special two-phase flow instabilities at full power natural circulation reactor condition
Authors: Zhang Y. J. , Yang X. T. , Jiang S. Y.
Published: December 2013

The experiments were performed on the test loop HRTL-5, which simulates the geometry and system design of the 5 MW nuclear heating reactor. In a wide range of inlet sub-cooling various flow instabilities were observed at p = 0.1 MPa and p = 1.5 MPa. Because of the different geometry design and operating conditions between the heating reactors and the boiling water reactors, the flow behavior presents great difference. Analysis shows: (1) under heating reactor conditions, sub-cooled boiling, condensation and void flashing are the fundamental thermodynamic processes; (2) sub-cooled boiling, condensation, void flashing and the compressibility of the steam space play an important role in the flow instabilities of the natural circulation system; (3) sub-cooled boiling instability, flashing instability, and flow excursion are the special instabilities at nuclear heating reactor conditions.
Dynamics of radionuclides in forest ecosystems
Authors: Steiner M.
Published: December 2013

The unique physiology and the layered structure of forest ecosystems result in dynamic transport and transfer processes which greatly differ from those in agricultural ecosystems. Radionuclides are retained in the upper organic horizons of forest soil for several decades and remain highly available for uptake by fungi and green plants. Contamination levels of mushrooms and game may therefore by far exceed those of agricultural produce. The efficient cycling of nutrients and radionuclides, which is characteristic for ecosystems poor in nutrients, can largely be attributed to forest soil with its complex and multi-layered structure and fungal activity. Fungi directly affect dynamic processes, playing a key role in the mobilization, uptake and translocation of nutrients and radionuclides. Fungal fruit bodies may be highly contaminated foodstuff and fodder. They are most likely the cause of the surprising trend of increasing contamination of wild boar which has been observed in the last few years in Germany. This paper is intended to give a qualitative survey of dynamic transport processes in forests and their relevance for radiation exposure to man.
Fast determination of strontium radionuclides in milk with the aid of the cryptand 2.2.2
Authors: Tait D. , Haase G. , Hartmann R.
Published: December 2013

A rapid method for separating strontium (Sr) radionuclides from liquid milk has been improved and tested for the determination of Sr-90 in milk. The method is based on the specific extraction of Sr from the milk with cryptand 2.2.2 on a cation exchange resin (Dowex Marathon C). Decontamination from other radionuclides such as those of caesium and from chemically similar elements such as calcium and barium is efficient. At least 6 samples can be treated in one day by one person. Tests were carried out on series of six 1.0 and 0.10 litre milk samples representing respectively routine milk samples and samples for fast analysis i.e milk contaminated with fresh fallout, including Ba-140, and requiring barium separation. For the 1.0 litre samples Sr recoveries ranged from 75–85 % while for 0.10 liter samples the range was 65–80 %. Conditions for the use of Sr-85 as yield tracer to correct for the losses were established. The method minimizes the handling of hazardous reagents.
Results of the investigation on natural radiation exposure due to ingestion
Authors: Wichterey K. , Beyermann M. , Kümmel M.
Published: December 2013

Results of a nationwide measuring programme in Germany are presented where long-lived natural radionuclides of the uranium and thorium series in samples of daily total diet were analysed. Typical ranges and average values of the specific activities are given. There are neither differences between the specific activities in total diet for adults and the age group ≤1 year nor meaningful regional differences. The resulting dose due to ingestion of natural radionuclides has been deduced for all age groups and evaluated. The radionuclides 210Pb, 210Po, 228Ra and 226Ra are responsible for about 90 % of the total ingestion dose which is 0.09 mSv per year on average without 40K contribution.
Regulation of nuclear decommissioning
Authors: Wendling R. D. , Paul M.
Published: December 2013

Being an integral part of the life of all nuclear facilities, the decommissioning of these facilities is an important task to the owners as well as to the regulators and authorities. This applies not only to large nuclear facilities such as power plants and fuel cycle facilities but is also referring to the multitude of small nuclear applications in medicine, industry and research. The article provides an overview of the statutory and legal framework, the regulatory body and the licensing procedure for the decommissioning and dismantling of nuclear facilities in Germany. Furthermore, the respective international regulatory framework as it is laid down in the Joint Convention and the IAEA Safety Standards is outlined and a brief description of the current activities of WENRA is given.
The role of clearance in Germany – release of materials, buildings and sites
Authors: Thierfeldt S.
Published: December 2013

Clearance in Germany is far advanced. A complex regulatory framework exists in the Radiation Protection Ordinance (RPO/Strahlenschutzverordnung, StrlSchV) since 2001 which has replaced previous recommendations on clearance issued by the German Radiation Protection Commission (Strahlenschutzkommission, SSK). A number of options exist both for unconditional clearance (e. g. of all kinds of materials with no restrictions on the destination or future use) and for clearance for a specific purpose (e. g. recycling of metal scrap). For each clearance option there is a set of nuclide specific clearance levels which have been derived on the basis of the 10 Sv/a individual dose criterion using complex radiological models which are tailored to the respective material cycles (metal scrap, buildings, building rubble, waste for disposal, sites). The clearance levels have been thoroughly reviewed by the SSK. An extensive comparison to sets of clearance levels used in other countries or issued as guidance by international bodies revealed that the correspondence between values is between good and acceptable taking into account country-specific approaches and special assumptions which would not necessarily pertain to German situations. Clearance is a major factor in the material management, especially of nuclear installations undergoing decommissioning. The variety of clearance options leaves the operator of a nuclear installation sufficient flexibility for optimisation of the material management. Clearance is of particular importance in a country like Germany where the estimated costs for a future repository are very high and the interim storage facilities for radioactive material are limited and costly. While the licensee is responsible for his material management, the issuance of a clearance permit is done by the regulatory body upon application. The regulators may choose to use the clearance levels and regulations as stipulated by the RPO, or to impose site-specific regulations on the licensee. The actual clearance measurement, i. e. checking the compliance of the residual radionuclide content in or on a particular material, building or site with the clearance levels, is performed under the responsibility of the licensee's appointed radiation protection officer, with additional checks usually made by the regulator or an independent expert acting on his behalf. After compliance verification, the material will be reused, recycled or disposed of according to the clearance option, being then subject to the conventional waste legislation.
Decommissioning of back-end nuclear facilities
Authors: Dagbjartsson S.
Published: December 2013

Concerning the decommissioning of facilities related to reprocessing of spent nuclear fuel and processing and disposal of radioactive waste, i. e., facilities for waste conditioning or storage, specific features prevail. Such facilities are generally optimised for the handling of radioactive substances and, therefore, are frequently highly contaminated, but do not contain any activated material. One main concern of their decommissioning will usually be the decontamination of extended surfaces of process equipment and building structures. Depending on the extent and success of the decontamination, dismantling tasks might have to be remotely performed. Based on a survey of the number of such facilities, typical issues associated with their decommissioning were found to be well presented by focussing on the examples of the decommissioning of the two prototype spent fuel reprocessing plants at Dessel/Belgium and Karlsruhe/Germany. Such issues are mainly associated with the presence of alpha-contamination of the process equipment and large building structures. Experience gained from solving associated problems is discussed.
Decommissioning and rehabilitation of uranium and thorium production facilities
Authors: Hagen M. , Kunze C. , Schmidt P.
Published: December 2013

The use of nuclear energy for military as well as for peaceful purposes was and remains closely connected with the mining and processing of uranium ore and, to a lesser extent, of thorium ore. Mining and processing of radioactive ores are characterised by the generation of huge amounts of radioactive residues, massive impacts upon ecosystems, landscape reshaping (or devastation in some places), and the monostructural socio-economic orientation of human settlement areas. However, a great number of the mines and mills commissioned during the cold war have been already closed, either for deposits being depleted of economically recoverable resources or on political grounds. The specifics of uranium/thorium mining and milling make high demands on the decommissioning and rehabilitation of the facilities which in addition to radiological aspects would have to address issues such as water pollution control and soil conservation, future site re-use, landscaping, and infrastructure development. The present paper gives an overview of the state of decommissioning and rehabilitation. Radiological specifics and their integration into the decommissioning and rehabilitation management are demonstrated for the rehabilitation of uranium mining legacies in Saxony and Thuringia.
Measurement of the neutron fluence on the spallation source at Dubna
Authors: Adam J. , Barashenkov V. S. , Ganesan S. , Golovatiouk S. , Gupta S. K. , Kailas S. , Krivopustov M. I. , Kumar V. , Kumawat H. , Palsania H. S. , Pronskikh V. , Sharma Manish , Tsoupko-Sitnikov V. M. , Vladimirova N. , Westmeier H. , Westmeier W.
Published: December 2013

A232Th activation sample was exposed directly to the spallation neutrons produced by 1GeV proton colliding with a lead target and other samples of197Au,209Bi,59Co,115In and181Ta were irradiated by moderated neutrons after passing through 6 cm of paraffin. Different (n, γ) and (n, xn) reaction products in232Th,197Au and209Bi samples are analyzed by gamma-ray spectrometry to measure the neutron fluence at the positions of the samples. For this purpose a histogram of ‘flat’ spectrum averaged neutron cross-sections in over thirty given energy groups was determined from the PREPRO-2000 software. Results of measurements are compared with Monte-Carlo simulations by the Dubna CASCADE code. Experimental values for both spallation and moderated neutron fluences are in reasonable agreement with the CASCADE code. Thus, the experimentally measured fluence of moderated neutrons was used to infer the ‘one group’ reaction cross-sections of209Bi (n, xn) reactions for x = 6 to 9.
Neutron reflection and leakage models for one-dimensional reactor computations
Authors: de Abreu M. P.
Published: December 2013

Exact discrete ordinates interface conditions were derived for neutron reflection and leakage for one-dimensional nuclear reactor computations with anisotropic scattering. The key to our derivation is a suitable reformulation of exact discretized equations – spectral nodal equations defined in the nonactive surrounding regions of nuclear reactor cores. As a result, interface conditions are obtained that can advantageously replace the nonactive surrounding regions of a nuclear reactor core in reactor computations. Numerical experiments with a representative one-dimensional code and an axial core model with anisotropic scattering were performed in order to illustrate the improvements that can be experienced by most one-dimensional discrete ordinates nuclear reactor codes with our interface conditions.
The singular eigenfunction method: the critical slab problem for linearly anisotropic scattering
Authors: Türeci R. G. , Güleçyüz M. Ç. , Kaşkaş A. , Tezcan C.
Published: December 2013

The critical slab problem for linearly anisotropic scattering is investigated using the singular eigenfunction method. The third form of the transport equation is considered. The singular eigenfunctions for linearly anisotropic scattering are inserted into the Green's function. This Green's function with the full range orthogonality relations of the singular eigenfunctions together with the appropriate boundary conditions provide the criticality equation. This equation is exact and leads as shown in tables to fast converging numerical results.
Integrated management systems in the nuclear field
Authors: Beckmerhagen I. A. , Berg H. P. , Karapetrovic S. V. , Willborn W. O.
Published: December 2013

In the last years several internationally accepted standards such as the ISO 9000 and ISO 14000 series and other function-specific management systems standards have been developed. At the same time, it has become imperative for organisations to continuously improve their overall quality, environmental and safety performance. Therefore, the need to create integrated management systems is of growing importance to enable an easier handling of the different management systems. This paper has two main objectives. The first one is to address the key issues in the underlying theory of integrated management systems including benefits and limits, the second one is to illustrate the importance of an integrated (in particular safety) management system and the experience feedback providing examples from different areas and different organisations in the nuclear field.
Phenomenological model for non-equilibrium deuteron emission in nucleon induced reactions
Authors: Broeders C. H. M. , Konobeyev A. Yu.
Published: December 2013

A new approach is proposed for the calculation of non-equilibrium deuteron energy distributions in nuclear reactions induced by nucleons of intermediate energies. It combines the model of the nucleon pick-up, the coalescence and the deuteron knock-out. Emission and absorption rates for excited particles are described by the preequilibrium hybrid model. The model of Sato, Iwamoto, Harada is used to describe the nucleon pick-up and the coalescence of nucleons from the exciton configurations starting from (2p, 1h). The model of deuteron knock-out is formulated taking into account the Pauli principle for the nucleon-deuteron interaction inside a nucleus. The contribution of the direct nucleon pick-up is described phenomenologically. The multiple pre-equilibrium emission of particles is taken into account. The calculated deuteron energy distributions are compared with experimental data from 12C to 209Bi
Thermal-hydraulic assessment of topaz irradiation processes at the ETRR-2 research reactor
Authors: El-Morshdy S. El-Din
Published: December 2013

The present work is carried out in order to evaluate the cooling process of irradiated topaz at the Egyptian Second Research Reactor (ETRR-2). A mathematical model is developed to simulate the cooling process of a part of the irradiation grid containing one topaz irradiation box. The coolant flow rate distribution through the model channels is estimated taken into consideration the buoyancy effect in each channel. The coolant temperature distributions along the model channels are predicted as well. The COSMOS/M finite element code is used to estimate the temperature distribution through one irradiated topaz stone. The predicted coolant and surface temperature values show the efficient cooling of topaz stones irradiated at the ETRR-2 research reactor.