bluuebunny/crossref_metadata_2025 huggingface dataset:
Shape- and Topology-Based Structural Die Design Using Differential Evolution and Response Surface Methodology for Sheet Metal Forming
Authors: Karen İdris , Kaya Necmettin , Öztürk Ferruh
Published: December 2013

The goal of this research is to describe how simulation and topology design can be used as a die design frame tool to introduce optimal die design structures with the desired maximum rigidity and minimum deformations using response surface methodology and differential evolution algorithms. In the simulation process, not only die deflection, but also press table deflection is taken into account in order to achieve more realistic results. The validation of the present approach is evaluated by a comparison of test and simulation results. In the experimental test, acceleration and strain data were measured from critical points of the die structure in order to obtain the maximum displacement and stress values. The optimal shape parameters for the die structure were obtained using response surface methodology and differential evolution as a fundamental optimisation technique. Significant results were obtained: The mass was reduced approximately about 24 %, and the current maximum stress decreased approximately about 72 %. By using this methodology in the design stage of die and sheet metal stamping, major improvements can be made to the vehicle development process, such as reducing the weight and the cost of die, reducing the labour costs during the tryout process and reducing the environmental damage and CO2emissions by reducing the amount of cast iron.
Process Capability Analysis in Machining for Quality Improvement in Turning Operations
Authors: Kahraman Funda , Esme Ugur , Kulekci Mustafa Kemal , Kazancoglu Yigit
Published: December 2013

Process capability indices are effective tools for both, process capability analysis and quality assurance. In quality assurance programs, process capability indices reflect the performance of key quality characteristics for a control process. Quality assurance in mass production is enabled by using statistical process control techniques. In this study, various statistical process control techniques were carried out using the measured values taken from the workpieces that represent the whole process in the medium sized company. The chances for using statistical techniques for quality estimation processes have been discussed. For this purpose, normal probability plots and histograms were prepared and the process capability indices were calculated. As a result of this study, it turned out that the process capability for the whole process was inadequate and the mass production was unstable. Some actions must be taken by engineers to improve the quality level by shifting the process mean to target value and reducing the process variation.
Structural and Spectroscopic Analysis of 1, 2-bis (Ethoxycarbonyl) Hydrazine and Computational Study on its Vibrational Properties
Authors: Ruan Min , Li Wen
Published: December 2013

The crystal of 1, 2-bis (ethoxycarbonyl) hydrazine was studied by XRD, FTIR and Raman spectroscopy. The ground-state geometries were optimized at B3LYP/6–31+G (d, p) level. These vibrational wavenumbers were calculated at the same level. The antibacterial activities have been screened for the compound against two bacteria: Staphylococcus aureus and Escherichia coli.
A Study on the Recycling of Aluminium Alloy 7075 Scrap
Authors: Özer Gökhan , Burgucu Sarp , Marsoğlu Müzeyyen
Published: December 2013

Aluminium and its alloys have recently become an important metal whose area and amount of usage increase more and more, due to their mechanical properties, recycling ability, and penetrability. If it is considered that the bauxite, which is the raw material of aluminium is rare on earth, and also the area and amount of aluminium usage increases over time, the importance of aluminium recycling goes up. aluminium recycling has become crucial by means of both, the potential of the scrap's dependant increase on usage and the primary aluminium production, as it is providing energy and cost savings. 7xxx grades of scrap are collected with other scrap of aluminium alloys in one turn and recycled all together. As the regain of these alloys is not done by isolation oft he various grades, the finally recycled ingots result in lower grades. High value aluminium scrap is regrettably not recovered, as it was anticipated. This study is dealing with 7075 aluminium alloys originated from discharged blow molding tools and the rest piece cuttings of blocks and plates. The material has been subjected to an induction furnace, and has been remelted into small ingots and hardened according to 7075 aluminium alloy parameters (hardening aluminium tooling).
Fracture Toughness of Alumina Ceramics Determined by Vickers Indentation Technique
Authors: Majić Marijana , Ćurković Lidija
Published: December 2013

Fracture toughness (KIC) of high purity cold isostatically pressed alumina ceramic (CIP-Al2O3) was determined from the size of cracks induced by Vickers hardness testing at wide range of loads. The observed cracks appeared at following loads: 4.905 N, 9.81 N, 29.43 N and 49.05 N. The studied material exhibits half-penny crack system at lower load of 4.905 N, but it proceeds as the Palmqvist crack system at higher loads, which was determined computationally. For the fracture toughness calculation different models were compared. It was found that fracture toughness increases by rising applied load for all kind of models, which is explained by the indentation size effect. As the fracture toughness overestimation can lead to product malfunction, it is suggested to use the Niihara model, which gives the smallest fracture toughness values.
New Softeners for Polyvinylchloride
Authors: Zeynalov Eldar B. , Maherramova Shahnaz N. , Sadieva Nazilya F. , Iskenderova Sevil A. , Agayev Bahadur K. , Friedrich Joerg F.
Published: December 2013

Production of new types of effective and green softeners for polyvinylchloride (PVC) is one of the important concerns in chemical industry. The paper reports results of investigations on obtaining symmetric esters of a series of fatty acids and triethylene glycol (TEG) and their use as effective PVC plasticizing agents. The esterification process was conducted in the presence of nano-grade titanium dioxide Degussa P-25 and specified by environmentally sound technology. Good compatibility and low volatility of the bio-based type esters in PVC formulations were shown and higher physico-mechanical features of the PVC composites were established. The esters may be recommended as effective and environmentally friendly PVC softeners to replace commonly used phthalates.
Investigation of the Influence of the Pre-Aging Process on the Hardness of 6082 and 7075 Aluminum Alloys
Authors: Şahin Salim , Durmuş Hülya , Yüksel Nilay
Published: December 2013

In this study, the effect of pre-aging time and temperature on mecha­nical properties of aluminium alloys 6082 and 7075 has been investigated. Pre-aging has been applied at 50, 60, 70 and 80 °C for 24, 72, 144 hours after solution treatment process at 560 °C for 1 hour. Then these samples have been subjected to an aging process at 180 °C and 125 °C. The hardness of samples has been measured during aging process regularly. Eventually, it was determined that if pre-aging process is performed at low temperature, an increase of hardness occurs and hardness decreases with increasing temperature during aging.
X-ray Residual Stress Analysis of Nitrided Low Alloyed Steels
Authors: Hoffmann Joachim Ernst , Zgani Marouan , Scholz Dirk , Altendorfer Margit , Clemens Helmut , Kübler Ralf
Published: December 2013

Residual stress analyses were performed on nitrided, low alloy steels by varying the measuring conditions. The measurements were carried out in the compound layer on ∊-Fe2–3N and γ′-Fe4N as well as in the diffusion layer on α-Fe. By considering different criteria, tensile residual stresses of up to 300 MPa produced, {111}-interference, for ∊-Fe2–3N using CuKα radiation on the specimen's surface. After removing 5 μm from the surface, compressive residual stresses occur in this phase. On employing the CrKα and CuKα radiation, relatively high compressive stresses are obtained of up to above −1000 MPa for γ′-Fe4N. For measurements using CrKα radiation, compressive residual stresses result in the diffusion layer for α-Fe, which have a maximum value below the surface. Here, the measurements of the {211}-interference give lower residual stress magnitudes than measurements of the {110}- and {200}-interferences. By verifying the phase superpositions, the linear distributions of line positions or the comparable loading stress analysis using XRD or strain gauges, the results determined at the {211}-interference appear to be realistic. Attention should be paid to the high penetration depth of CrKα radiation. Here, no gradients of the investigated stress states may exist which are too large. The steel possessing a higher content of nitride forming elements such as Al, for example, mainly exhibit the highest compressive residual stresses. In the diffusion layer of 34CrAlNi7-10, maximum compressive residual stresses of −800 MPa result at {211}-interference in α-Fe.
Evaluation and Optimization of Operating Parameters Affecting the Davis Tube Magnetic Tester by Using 2ndFactorial Design
Authors: Abdel Haffez Gamal S. , Abu-Ali Mohamed Hussein
Published: December 2013

The current practice of assessing the efficiency of recovery of magnetite is represented by Davis tube tests based on magnetic induction. 2ndfactorial design is used for the parametric study of the magnetic separation, because the classical approach is a tedious method. Factorial design is the most efficient way to explore the combinations of variables, because it considers every observation and uses only the most necessary observations. The results of the factorial experiments were used to identify the variables having a significant effect on magnetic recovery. The main objective of this work is to upgrade the iron ore using the Davis tube magnetic tester. It is also intended to study the most important operating parameters affecting the separation process. Among these are the feed size (μm), current intensity (A), tube oscillation (rpm), tube inclination (degree) and wash water rate (l/min). Consequently, the best fit relation can be expressed mathematically as: Y = 58.99 + 7.25X + 4.56I — 1.49O — 2.19W — 1.84S.
Terahertz Time Domain Spectroscopy for Non-Destructive Testing of Hazardous Liquids
Authors: Chrzanowski Lars S. von , Beckmann Jörg , Marchetti Barbara , Ewert Uwe , Schade Ulrich
Published: December 2013

Hazardous liquids, liquid explosives and flammable liquids are characterized by means of terahertz time domain spectroscopy (THz-TDS) in analogy to existing non-destructive testing (NDT) strategies. Various polar liquids (alcohols, acetone, hydrogen peroxide, nitro methane) and non-polar aircraft and automobile fuels as well as organic solvents are characterized in the practically relevant, non-contact and non-destructive reflection geometry in the time domain. Absorption coefficients and indices of refraction of a representative set of these liquids are investigated in the spectral range between 0.1 THz and 1.1 THz in transmission configuration by two different set-ups either suitable for strongly or weakly absorbing liquids.
Schwingfestigkeitsanalyse struktureller Klebverbindungen unter Belastung mit variablen Amplituden*
Authors: Schmidt Halvar , Bruder Thomas , Hanselka Holger
Published: December 2013

Kurzfassung

Das Fügeverfahren Kleben gewinnt unter dem Gesichtspunkt Leichtbau aufgrund seiner Eigenschaften wie erhöhte Steifigkeit, verbessertes Crash-Verhalten und Fügbarkeit nichtmetallischer Werkstoffe (beispielsweise GFK oder CFK) stetig an Bedeutung. Der vorliegende Beitrag beschreibt die Entwicklung einer neuartigen, bauteilähnlichen Probenform zur Schwingfestigkeitsanalyse struktureller Klebverbindungen. Deren Schwingfestigkeitsverhalten unter Belastung mit variablen Amplituden wird aufgezeigt. Reihenfolgeeffekte wurden festgestellt. Basierend auf diesen Erkenntnissen wird neben der für die rechnerische Lebensdaueranalyse benötigten Schadensakkumulation auf die Energie­freisetzungsrate zur Abschätzung einer Versagensgrenze eingegangen.
Mechanische Kurzzeitprüfung zur Bewertung des Verhaltens von PE-Rohrwerkstoffen beim langsamen Risswachstum*
Authors: Langer Beate , Berthold Anja , Grellmann Wolfgang , Enderle Hans-Friedrich
Published: December 2013

Kurzfassung

Die Kenntnis der Deformations- und Schädigungsmechanismen beim langsamen Risswachstum in Polyethylen (PE)-Rohrwerkstoffen ist im Hinblick auf ihre Lebensdauervorhersage von besonderer Bedeutung. Eine etablierte Möglichkeit der Simulation und Vorhersage des langsamen Risswachstums ist der Full-Notched Creep Test (FNCT), der besonders bei den heute verwendeten PE-Rohrwerkstoffen durch sehr lange Prüfzeiten gekennzeichnet ist. Aus diesem Grund wurde in der vorliegenden Arbeit nach Korrelationen gesucht, die zwischen Methoden der Kurzzeitprüfung und dem Full-Notched Creep Test bestehen. Als Methoden der Kurzzeitprüfung wurden die für Kunststoffe etablierten bruchmechanischen Konzepte “Essential Work of Fracture” und “Risswiderstandskurve” gewählt.
Neues aus der Normung auf dem Gebiet der mechanisch-technologischen Prüfverfahren*
Authors: Blum Jenny
Published: December 2013

Kurzfassung

In diesem Beitrag werden die neuesten Entwicklungen in der Normung auf dem Gebiet der Werkstoffprüfung folgender Gebiete vorgestellt: mechanisch-technologische Prüfverfahren (Härteprüfung, Zugversuch, Kerbschlagbiegeversuch) und Kalibrierung von Werkstoffprüfmaschinen.
Instrumentierte Eindringprüfung zur Bestimmung lokaler Festigkeitskennwerte an Punktschweißverbindungen
Authors: Brauser Stephan , Subaric-Leitis Andreas , Ullner Christian , Rethmeier Michael
Published: December 2013

Kurzfassung

Die lokalen Festigkeiten im Bereich einer Schweißverbindung sind maßgebend für deren Widerstandsfähigkeit gegenüber mechanischen Beanspruchungen. Im Gegensatz zu anderen präparationsaufwendigen Methoden, z.B. die Untersuchung von Mikro-Zugproben, liefert die instrumentierte Eindringprüfung mit deutlich geringerem Aufwand Verläufe von Festigkeiten mit sehr guter Ortsauflösung. Im Rahmen dieser Arbeit werden wahre Spannungs-Dehnungskurven aus zyklischen Eindringversuchen mittels Auswertungen auf der Basis repräsentativer Spannungen und Dehnungen und auf der Basis neuronaler Netze an Punktschweißverbindungen aus hochfesten Stählen, jeweils im Bereich des Grundwerkstoffs und der Schweißlinse, bestimmt. Die Ergebnisse werden exemplarisch für einen Stahltyp mit Ergebnissen von Zugversuchen am Grundwerkstoff und am thermisch behandelten Werkstoff mit Schweißgut ähnlicher Struktur verglichen und diskutiert.
Influence of Heat Treatment Parameters on the Microstructure and Mechanical Properties of Boron-Alloyed Steels
Authors: Güler Hande , Ertan Rukiye , Özcan Reşat
Published: December 2013

This paper focuses on the effect of heat treatment parameters on the microstructure and mechanical properties of quenchable 22MnB5 steel sheets with an Al–Si layer. Heat treatment parameters such as temperature and cooling rate from the solid solution temperature were investigated. For this purpose, the heat treatment was conducted within the temperature range from 700°C to 950°C, and two different cooling techniques were applied to the specimens: air cooling and water quenching. The microstructures of the specimens were then studied using optical microscopy. Additionally, tensile and hardness tests were performed at room temperature. The results show that the effects of heat treatment were obviously influenced by the original microstructure of the 22MnB5 sheet. With the increase of heat treatment temperature, the martensite proportions increased, and the hardness and tensile strength also increased, especially after the 850°C quenching. Moreover, quenching after 900°C has been reached was determined to be an ideal process for hot forming 22MnB5 steel sheets.
Tribological Properties of Sn-Pb Based SnPbAlZn Journal Bearings
Authors: Ünlü Bekir Sadik , Pinar Ahmet Murat , Özdin Kamil
Published: December 2013

Tin and lead based alloys are widely used as journal bearing materials in tribological applications. If Al or Zn with their sliding property will be added to such materials the tribological properties of journal bearings can be improved once more. In this study, wear properties of these journal bearings manufactured from SnPbAlZn, pure Sn, pure Pb, pure Al, and pure Zn bearings were investigated. Experiments were carried out in every 30 min for the total of 150 min by using radial journal bearing wear test rig. As a result wear properties can be improved by variation of SnPbAlZn material.
The Effect of Plasma Arc Process Parameters on the Properties of Dissimilar AISI 1040/AISI 304 Steel Plate Welds
Authors: Kiliç Musa , Kirik İhsan , Celik Ferkan , Orhan Nuri
Published: December 2013

In this study, 10 mm thick AISI 1040 and AISI 304 steel plates were welded in the butt position without pretreatment by plasma transferred arc (PTA) welding technique. Therefore, mechanical behaviour, microstructure, penetration depth and length were investigated. After welding, microstructural changes in the interface regions of the welded specimens were examined by scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). Micro-hardness as well as V-notch Charpy tests were performed to determine the mechanical properties of the welds. The influence of the welding parameters on the dimension and shape of the joints has been found out. From the results, it was derived that with the parameters used, a partly keyhole weld bead formed with a penetration depth of 10 mm and a width of 11 mm in butt position.
Glimmentladungsanalyse (GD-OES) buntgehärteter Stahloberflächen
Authors: Schnapp Jürgen Dieter , Weber Heike , Schilling Jörg , Wilke Marcus
Published: December 2013

Kurzfassung

Das Bunthärten wird traditionell zur hochwertigen, ästhetischen Oberflächenveredelung ferritisch-perlitischer Stähle vor allem für Komponenten von Jagd- und Sportwaffen verwendet. Diese weltweit von wenigen Werkstätten praktizierte Technologie war bisher empirisch orientiert und wurde weitgehend geheim gehalten. Die Struktur der buntgehärteten Randschichten wird hier mit der relativ neuen Methode der Glimmentladungsanalyse (GD-OES) untersucht und mit den Herstellungsparametern korreliert. Eine hochwertige Bunthärtung mit gewünschter marmorierter Farbstruktur und guten mechanischen und chemischen Eigenschaften ist an die Bildung von mehreren charakteristischen Randschichten mit typischen Kennwerten der chemischen Zusammensetzung, Struktur, Gefüge und deren Tiefenprofilen gebunden. Die untersuchten unlegierten und niedriglegierten Stähle haben vergleichbare Schichten, die durch technologie- und werkstoffspezifische Parameter erreicht werden.
A New Approach to Iznik Tiles
Authors: Sarigüzel Meryem , Günay Esin
Published: December 2013

Traditional Iznik ceramics (tile and pottery) are known as “unproducible” due to their high quartz content and unique processing steps. During the course of this study, a comparison of traditional and modern Iznik tiles in colour and brightness carried out. As latest insights of recent studies showed that the production techniques and the size of pigments are crucial parameters for the quality of colours of ceramics. Therefore, Iznik tiles were shaped by dry press without changing their quartz content. Secondly, paints to be applied in the decor stage were prepared with both traditional and nanometersized pigments and used in production process. Finally, characterization techniques were used in order to understand and compare the results and also the effects of nanometer sized pigments on Iznik tiles.
Innovative Ultrasonic Testing Facility for Fatigue Experiments in the VHCF Regime*
Authors: Heinz Stefan , Balle Frank , Wagner Guntram , Eifler Dietmar
Published: December 2013

At the Institute of Materials Science and Engineering of the University Kaiserslautern an ultrasonic testing facility was developed to perform fatigue tests in the VHCF regime. The individual design of the ultrasonic testing facility allows to control the process parameters and to measure relevant data with a frequency of up to 500 kHz in reasonable time. This permits a high-resolution measurement of the ultrasonic oscillation and the dissipated energy as well as a determination of microstructural reactions inside the specimens. With the described ultrasonic testing facility constant amplitude tests and load increase tests were carried out with the alloy Ti6Al4V. The results show that the innovative test and measuring techniques are best suited to describe the fatigue behaviour of Ti6Al4V. Additionally, for the first time high resolution 3D scanning laser vibrometry were carried out to determine the oscillation behaviour of specimens under ultrasonic cyclic load.
Assessment of the Residual Strength Thresholds of Composite Pressure Receptacles – Criteria for Hydraulic Load Cycle Testing
Authors: Mair Georg W. , Hoffmann Martin
Published: December 2013

The current practice of periodic retesting of composite pressure receptacles primarily based on the hydraulic pressure test has to be evaluated as critical. This is justified by micro damages caused to the specimen by the test itself and by a lack of informative values. Thus, BAM Federal Institute of Materials Research and Testing uses a new validation approach in the case of retest periods of more than 5 years. It enables the description of the condition of a specific design type series based on destructive tests parallel to operation. With respect to this approach it is explained how the statistical evaluation of sample tests and their extrapolation to end of life or at least to the time of next retesting can be achieved. In addition, it is explained how the reliability limits may be linked to the size and pressure level of the respective composite pressure receptacle. The frame of this safety approach includes the influence of the maximum working pressure on the safety assessment. One topic of this approach is the introduction of the working diagram essential for safety assessments that allows graphical evaluation of load cycle strength by mean value, scatter and survival rate of samples as well as instruction how to use it. For this, it is explained how the number of filling cycles and the reduction of the respective hydraulic residual cycle strength interacts with the newly introduced value of specific filling sensitivity.
Ferroelektret-Prüfköpfe für die zerstörungsfreie Prüfung mit Luftultraschall
Authors: Döring Joachim , Bartusch Jürgen , Gaal Mate , Kreutzbruck Marc , Erhard Anton , Bovtun Viktor
Published: December 2013

Kurzfassung

Für die luftgekoppelte Ultraschall-Prüfung wird der Prototyp eines neuartigen Prüfkopfes vorgestellt. Statt eines piezokeramischen Ultraschall-Wandlers mit einer λ/4-Anpassschicht wird eine Ferroelektret-Folie aus schaumförmigem Polypropylen eingesetzt. Durch die außerordentlich geringe akustische Impedanz der Folie reduzieren sich die Reflexionsverluste an den Grenzschichten zur Luft so stark, dass bei diesem Prüfkopf auf eine λ/4-Anpassschicht verzichtet werden kann. Außerdem ist die Folie hochspannungsfest. Sie konnte mit Spannungen von mehr als 3500 V angesteuert werden und erlaubte eine Vorspannung am Ultraschall-Wandler des Empfangsprüfkopfes von 2000 V. Mithilfe der hohen Anregungsspannung stieg die Amplitude des akustischen Prüfimpulses auf das 11,2-Fache. Die Empfindlichkeit des Empfängers erhöhte sich durch die Vorspannung weiter um den Faktor 4,3. Insgesamt steigt die Amplitude am Empfänger also auf das 48-Fache, bei gleichbleibendem Rauschpegel. Ein abschließender Vergleich mit kommerziellen Luftultraschall-Prüfköpfen belegt die Überlegenheit der Folien-Prüfköpfe. Damit rückt der Einsatz einer vollwertigen Impuls-Echo-Technik auch bei der luftgekoppelten Ultraschallprüfung deutlich näher.
The Effect of the Inclination Angle on Inverse Z Joints in Composite Materials Bonded with Adhesives
Authors: Adin Hamit , Turgut Aydın
Published: December 2013

The improvements in physical and mechanical properties of industrial adhesives show that adhesive bonding techniques can be successfully applied to the most engineering fields. Due to some of their advantages in comparison to fastening methods, adhesively bonded joints have been researched by many researchers. In this study, the effect of the inverse Z joints angle (IZJs) was both experimentally and numerically analyzed. Vinylester Atlac 580 and Flexo Tix were used as adhesives. Two different composite materials were the adherends. In order to identify the mechanical properties of the adhesives, the bulk specimen method was used. Finite Element Analysis (FEA) was performed with software Ansys (V.10.0.1). Experimental results were compared with numerical results and the comparisons were found to be reasonable. The results showed that angle of the specimen with the increase of the stresses increase as well. The stresses in the middle of the overlap length were also higher than those at the edge of the overlap length.
Materials Testing under Mechanical Stress, Pressure and Turbulent Flow of Impure Supercritical CO2
Authors: Ruhl Aki Sebastian , Göbel Artur , Kühn Hans-Joachim , Kranzmann Axel
Published: December 2013

The climate change necessitates measures to reduce carbon dioxide (CO2) emissions in the atmosphere, one of which is carbon dioxide capture and storage (CCS). Transmission of pressurized liquid or supercritical CO2 containing residual flue gas constituents in pipelines is an important component of CCS systems. Material testing under conditions as close as possible to real conditions is a prerequisite for reliable and safe implementation of CCS. A novel pipeline corrosion test facility was developed, accounting for major mechanical, physical and chemical influencing factors: elastic deformation, pressure, temperature, gas composition and flow velocity can be independently adjusted. Radial and tangential stress distributions on a round sample were experimentally investigated, indicating a good accordance with expected theoretical values. In this contribution the idea of the novel corrosion test facility and the assembled equipment as well as first results are presented and discussed.
Experimental Investigations on Yttrium Borate Phosphate Phosphors with Codoped Ce3+ and Tb3+ Ions
Authors: Limin Dong , Yanlong Sun , You Li , Chao Guo , Qin Li , Zhidong Han , Xianyou Zhang
Published: December 2013

Green phosphor of Y(BO3, PO4): Ce, Tb was synthesized by means of sol-gel and conventional solid state methods. The thermal formation process was characterized by thermogravimetric analysis (TG) and differential thermal analysis (DTA). The effects of synthesis conditions on the crystalline and morphological structures were investigated using the X-ray diffraction (XRD) and Scanning Electronic Microsocpy (SEM). The results revealed that Y(BO3, PO4): Ce, Tb phosphors with the monocline structure and high purity were successfully prepared by the sol-gel method. Furthermore, the products synthesized by the sol-gel method showed a well developed crystal structure, small particle size, narrow size distribution, and high luminescent performance. The product synthesized at 1050 °C in 2 h had better emission intensity than the others.
Human Factors Perspective on the Reliability of NDT in Nuclear Applications
Authors: Bertovic Marija , Fahlbruch Babette , Mueller Christina
Published: December 2013

A series of research studies have been conducted over the course of five years venturing into the fields of in-service inspections (ISI) in nuclear power plants (NPPs) and inspection of manufactured components to be used for permanent nuclear waste disposal. This paper will provide an overview of four research studies, present selected experimental results and suggest ways for optimization of the NDT process, procedures, and training. The experimental results have shown that time pressure and mental workload negatively influence the quality of the manual inspection performance. Noticeable were influences of the organization of the working schedule, communication, procedures, supervision, and demonstration task. Customized Failure Mode and Effects Analysis (FMEA) was used to identify potential human risks, arising during acquisition and evaluation of NDT data. Several preventive measures were suggested and furthermore discussed, with respect to problems that could arise from their application. Experimental results show that implementing human redundancy in critical tasks, such as defect identification, as well as using an automated aid (software) to help operators in decision making about the existence and size of defects, could lead to other kinds of problems, namely social loafing and automation bias that might affect the reliability of NDT in an undesired manner. Shifting focus from the operator, as the main source of errors, to the organization, as the underlying source, is a recommended approach to ensure safety.
Safe product design – the role of the NDT reliability analysis
Authors: Pavlovic Mato , Mueller Christina , Ewert Uwe , Ronneteg Ulf , Pitkänen Jorma , Boller Christian
Published: December 2013

In line with the damage tolerance design principles, an adequate non-destructive inspection system is needed to ensure structural integrity. Yet, when pushed to the limits of their detection capability, non-destructive evaluation systems do not produce consistent hit/miss indications. Their capability of detecting flaws is therefore expressed as a probability of detection. In the conventional signal response reliability analysis, the probability of detection is expressed as a function of the flaw size. The adequacy of the inspection system is verified by comparing the size of the flaw that is reliably detected with the maximum allowable flaw size, which will not undermine the structural integrity. Analyses of modern structures show that other parameters also determine the severity of the flaw for the structure. Within the multi-parameter reliability analysis, the probability of detection can be expressed as a function of diverse influencing parameters. When determining the adequacy of the non-destructive evaluation system, the capability of detecting a flaw has to be expressed and checked against the critical value of exactly that parameter that determines flaw severity for the structure. Failing to do so can lead to a rejection of the healthy, or acceptance of the bad part. The principle is demonstrated on the transmit-receive longitudinal ultrasonic inspection data of the iron cast component with surface, semi-elliptical, crack-like flaws.
Fabrication and Characterization of Bimetallic Mordenite-Zeolite Catalysts for Low Temperature Direct Decomposition of N2O Emitted from Nitric Acid Plants∗
Authors: Seo Minhye , Cho Sung-Su , Kwyon Byung-Chan , Lee Sungkyu
Published: December 2013

In this research, the mordenite based catalysts for direct decomposition of N2O have been prepared and characterized for their direct decomposition performance at the operating temperature of 300–550 °C commonly encountered in the nitric acid plants tail gases. The zeolite catalyst was prepared by 2 steps: 1. Precursor wet ion exchange, 2. Precursor impregnation. The bi-metallic catalyst thus prepared shows an excellent N2O decomposition performance. The total conversion efficiency of Pt-Fe-MOR catalyst has been achieved at 390 °C. XPS analysis confirmed platinum on mordenite supports in two forms: PtO and PtO2 species interact with oxygen ions at the metal/support interface. Deposition of Pt as a promoter on the surface of Fe-mordenite results in a considerable enhancement of catalytic activity.
Sea Water Effect on Failure Behaviour of Mechanically Fastened Composites
Authors: Sayman Onur , Ozen Mustafa , Sen Faruk , Benli Semih
Published: December 2013

In this study, sea water effect on failure behaviour was investigated for mechanically fastened composites that are oriented as [0/90/45/-60]s. The laminated composite specimens were fastened with two serial fasteners and were tested under non-immersed and immersed conditions, i. e. in sea water for 200 days. The experiments were carried out according to D 5229/D 5229M standard test method for evaluation of moisture absorption properties and equilibrium conditioning of polymer matrix composite materials. The results point out that the immersion into sea water of the composite specimens can cause a decrease in failure loads of both, pinned and bolted joints, particularly.
Herausforderungen bei der Auslegung und produktionstechnischen Umsetzung von Verbundlenkerhinterachsen für PKW∗
Authors: Frehn Andreas , Linnig Wolfram , Niggemeyer Norbert
Published: December 2013

Aufgrund der immer kürzer werdenden Entwicklungszeiten und des zunehmenden Kostendrucks bei der Entwicklung von Fahrzeugen und Komponenten wird die virtuelle Entwicklung weiter an Stellenwert gewinnen. Am Beispiel einer Verbundlenkerachse wird gezeigt, welche Kriterien bei der Auslegung dieses Bauteils berücksichtigt werden müssen, deren Verifizierung und Optimierung kontinuierlich über geeignete Test- und Untersuchungsverfahren erfolgen muss. Durch die virtuelle Validierung werden die Fertigungsprozesse variabel festgelegt, die notwendig sind, um die Anforderungen hinsichtlich Betriebsfestigkeit sicher zu erfüllen. In Kombination mit geeigneten Werkstoffen und Halbzeugen leisten diese einen wichtigen Beitrag zum Leichtbau und zur damit verbundenen Einsparung von CO2.
Schwingfestigkeit von Schweißnahtenden und Übertragbarkeit von Schweißverbindungswöhlerlinien∗
Authors: Kaffenberger Matthias , Vormwald Michael
Published: December 2013

Um die Geometrieeinflüsse von Schweißnahtenden genau erfassen zu können, wurden repräsentative Nähte mit einem hochauflösenden dreidimensionalen (3D) Scanner aufgenommen. Aus den gescannten Oberflächen konnten Volumenmodelle erstellt und anhand der Methode der finiten Elemente (FEM) elastizitätstheoretische Kerbspannungen berechnet werden. Aus diesen Ergebnissen wurde ein idealisiertes Nahtendmodell abstrahiert, welches in Bezug auf Größe und Verteilung nahezu die gleichen Kerbspannungen liefert wie die reale Geometrie. Zur Übertragbarkeit der Schwingfestigkeitsdaten wurde der spannungsmechanische und statistische Größeneinfluss in neuer Form kombiniert. Zur Lösung dieses Ansatzes wurde das numerische Verfahren NuMeSiS erarbeitet.
A general approach to automatic measurements of water velocity
Authors: Fu X. Q. , Liang X. , Liu X. , Liao W. T.
Published: December 2013

Real-time measurement of river flow velocity below the ice in winter is a tough problem. An experimental apparatus of a new thrust flow transducer based on the properties of particle phase is proposed in this paper. The traction cable's pull force which is given by the floating ball in the fluid can be measured by the experimental apparatus. Then the force values of the rigid floating ball are used to calculate fluid thrust on the floating ball. Finally, the velocity can be evaluated by an empirical formula between the fluid velocity and fluid thrust on the floating ball. Such a new thrust flow transducer is simple and requires only low costs. It can not only be used for measuring the surface velocity of rivers, water channels, lakes, and oceans, but can also be used for automatic measuring the velocity of water including frazil slush which is found below the ice sheets of rivers, water channels, lakes, and oceans in freezing conditions.
On the Biaxial Distribution of Anisotropic Elastic Modulus of Thin-Plate Polycrystalline Elements and the Identification by Ultrasonic Methods
Authors: Levi Avram Sabetaj
Published: December 2013

A new method for the interpolation of biaxial anisotropy of elastic modulus of thin-plate polycrystalline elements has been developed. The dependence of shear modulus and modulus of longitudinal elasticity as a function of an angular distribution of Poisson's ratio, achieved by the method of ultrasonic critical-angle refractometry (UCR), has been derived.
Einfaches Korrigieren des Hinterleuchtens von Röntgendetektoren
Authors: Kupsch Andreas , Hentschel Manfred P. , Lange Axel , Müller Bernd R.
Published: December 2013

Kurzfassung

Hinterleuchten stellt eine oft unerkannte Fehlweisung in der radiographischen Abbildung mit Flächendetektoren dar, die durch diffuse Umverteilung der Intensität verursacht wird. Dieser Effekt kann die korrekte Transmissions-Intensität eines Probekörpers gemäß dem Lambert-Beer'schen Gesetz erheblich verfälschen. Hinterleuchten wird sowohl mit Bremsstrahlung von Röntgenröhren als auch mit monochromatischer Synchrotronstrahlung beobachtet. Die fehlerhaft reduzierten Schwächungskoeffizienten von einigen 10 % korrelieren mit der Strahlschwächung und dem direkt bestrahlten Detektorbereich. Für eine einfache numerische Korrektur des Hinterleuchtens werden lediglich integrale Intensitätswerte benötigt.
Neue Methoden zur Analyse von diffusiblem Wasserstoff in hochfesten Stählen∗
Authors: Kühn Sebastian , Unterumsberger Fabian , Suter Thomas , Pohl Michael
Published: December 2013

Kurzfassung

Seit einigen Jahren werden für technische Konstruktionen vermehrt hochfeste Stähle mit Werkstofffestigkeiten von bis zu 2000 MPa eingesetzt, wie z. B. in der Automobilindustrie. Für den sicheren Einsatz von hochfesten Stählen ist es notwendig, kritische Wasserstoffgehalte und Belastungen zu kennen, bei denen nicht mit einer Beeinträchtigung der mechanisch technologischen Werkstoffeigenschaften und einem Materialversagen (Delayed Cracking) zu rechnen ist. Da hochfeste Stähle bereits bei sehr geringen Wasserstoffgehalten unter Zugbeanspruchung eine verzögerte Rissbildung aufweisen können, muss eine Wasserstoffanalysetechnik eingesetzt werden, welche eine exakte und reproduzierbare Analyse des schadensursächlichen diffusiblen Wasserstoffs im Bereich kleiner 0,1 ppm unabhängig vom Gesamtwasserstoffgehalt ermöglicht. In diesem Beitrag werden ein Verfahren zur hochgenauen integralen Analyse des diffusiblen Wasserstoffgehalts (HCA-Verfahren = Hydrogen Collecting Analysis) und ein elektrochemisches Verfahren zur Analyse von diffusiblem Wasserstoff in kleinen Werkstoffbereichen vorgestellt.
Mechanical Testing of Flow Drill Screw Joints Between Fibre-Reinforced Plastics and Metals
Authors: Szlosarek Robert , Karall Thomas , Enzinger Norbert , Hahne Clemens , Meyer Nils
Published: December 2013

The paper describes a novel testing method for mechanical joints between fibre-reinforced plastics and metals. As an example, the paper discusses a connection between a continuous carbon-fibre-reinforced plastic and aluminium via a flow drill screw. The failure load of the joints under different loading angles was tested with the help of a modified KS-II testing facility. A detailed analysis of the damage and failure behaviour of the connection was performed by means of optical recordings and micrographs. The results indicate that the tested material combination has nearly the same failure load at different loading angles with various failure mechanisms. The experimental results can be used to devise new failure criteria for these connections and to detect limit values for the design process.
Effects of Cobalt and Nickel/Cobalt Additions to P/M 304L Stainless Steel on Oxidation Behaviour at 900 °C and Mechanical Properties
Authors: Uoonahaseth Prangtip , Wangyao Panyawat , Lothongkum Gobboon , Chuankrekkul Nutthita , Tongsri Ruangdaj , Visuttipitukul Patama
Published: December 2013

This research investigated the effects of various cobalt and nickel/cobalt additions to P/M 304L stainless steel on oxidation behavior at 900 °C, hardness and bending strength. A single action press at 498 MPa was used for compacting powder mixture specimens. They were then sintered at 1300 °C for 30 minutes in hydrogen atmosphere and heat treated at 900 °C for 2, 5, 10, 20, 25, 40, 60, 80 and 100 hours in air for oxidation tests. It is clearly shown in the results that cobalt addition could improve density, hardness and bending strength. However, only 1 wt.-% Co addition was the best condition for oxidation resistance. The detrimental effect of Ni addition dominated the beneficial effect of Co addition, because its bigger powder size led to more pore formation. The resulting mechanical properties and oxidation behaviour depend on microstructures, porosity and powder size.
Mobile X-Ray Computed Tomography for Nuclear and Aviation Industry
Authors: Redmer Bernhard , Ewert Uwe
Published: December 2013

Digital detectors such as phosphor imaging plates (IP) and digital detector arrays (DDA) enable radiographic inspection with higher efficiency and improved image quality in comparison to the classic film technique. The mobile mechanised tomographic system TomoCAR (tomographic computer aided radiology) was developed first for inspection of circumferential welded seams of pipes. It consists of the manipulator based position control of an X-ray tube in front of the region to inspect and a digital detector array behind it. The high contrast sensitivity technique was combined with planar tomography. The tomographic reconstruction allows the three-dimensional (3D) representation of the material structure and included defects, equivalent to a metallographic cross sectioning. The hardware design is based on a specially developed flat X-ray tube and a direct converting CMOS detector array on CdTe basis. TomoCAR is applied for sizing of volumetric and planar defects. It allows the reliable detection of planar defects with openings larger than 25μm by subpixel resolution due to the achieved high signal-to-noise ratio. TomoCAR was successfully qualified as the result of a German pilot study on the basis of the European Network of Inspection and Qualification (ENIQ) guidelines for application in the nuclear power industry. Application examples are presented. The TomoCAR design was modified for in situ inspection of large aircraft components under production conditions. A gantry gate based planar tomograph was constructed and tested for inspection of the integrity of large flat CFRP panel components of up to 3 m × 9 m size. The integrity of imbedded stringers has been successfully observed. Different trials were performed to prove the finding rate of cracks in embedded stringers, which will be presented and discussed.
Theoretical and experimental investigations into natural circulation behaviour in a simulated facility of the Indian PHWR under reduced inventory conditions
Authors: Kumar N. V. Satish , Nayak A. K. , Vijayan P. K. , Pal A. K. , Saha D. , Sinha R. K.
Published: December 2013

A theoretical and experimental investigation has been carried out to study natural circulation characteristics of an Indian PHWR under reduced inventory conditions. The theoretical model incorporates a quasi-steady state analysis of natural circulation at different system inventories. It predicts the system flow rate under single-phase and two-phase conditions and the inventory at which reflux condensation occurs. The model predictions were compared with test data obtained from FISBE (Facility for Integral System Behaviour Experiments), which simulates the thermal hydraulic behaviour of the Indian 220 MWe PHWR. The experimental results were found to be in close agreement with the predictions. It was also found that the natural circulation could be oscillatory under reduced inventory conditions.
A method for in-situ quantification of oxygen in oil using fast neutron activation analysis
Authors: Owrang F. , Mattsson H. , Nordlund A.
Published: December 2013

The feasibility of an experimental methodology for in-situ quantification of oxygen in bulk oil using fast neutron activation analysis (FNAA) has been studied. The method was applied for determination of oxygen in 100 ml (∼ 90 g) rapeseed oil. The amount of oxygen in the rapeseed oil using the in-situ FNAA was estimated to 10.6 ± 2.6 weight %. Using cyclic fast neutron activation analysis (cFNAA), the amount of oxygen in the oil was determined in average 9.9 ± 0.4 weight %. Based on Monte Carlo calculations on water, the optimal radius and height of a cylindrical container where the activity is distributed through stirring of the water would be about 10 cm and 44 cm, respectively. These dimensions give a volume of about 14 liters, which is suitable for any type of oil. The accuracy in the in-situ FNAA can be increased by a more precise determination of oxygen in rapeseed oil in the beginning of a dynamic process using cFNAA or alternatively by a better background subtraction.
Investigation on bifurcation characteristics of a natural circulation system with low steam quality and low pressur
Authors: Jiang S. Y. , Yang X. T. , Zhang Y. J.
Published: December 2013

The two-phase flow is a kind of dissipative structure in multiphase hydrodynamics. A drift-flux model with four equations is adopted to investigate the natural circulation bifurcation, in which the sub-cooled boiling, condensation, and void fraction etc. have been taken into account. The bifurcation spectrum of a natural circulation system with low steam quality and low system pressure is presented and the physical mechanisms of bifurcation are described in detail. Bifurcation characteristics of the two-phase natural circulation indicate typical static instability observed in HRTL-5 simulating the geometry and system design of the 5 MW nuclear heating reactor operating at low steam quality and low system pressure. Analysis shows: (1) bifurcation phenomenon can occur in a two-phase natural circulation under certain thermal and geometrical condition; (2) with changing, namely increasing and decreasing, control parameters, the tracks of the work points of the natural circulation system are not identical, which shows the basic characteristic of the bifurcation phenomenon; (3) the bifurcation phenomenon of the natural circulation delay and disappear with increasing system pressure and decreasing heat flux.
Nitrogen transport in the primary circuit of a VVER during a LOCA occurring under plant cool-down conditions
Authors: Prasser H.-M. , Perneczky L. , Baranyai G. , Böttger A. , Ézsöl Gy. , Guba A. , Tóth I. , Zschau J.
Published: December 2013

The paper presents the results of a thermal hydraulic experiment conducted at the PMK-2 test facility within the IMPAM-VVER project. The test was dedicated to a loss-of-coolant event during the cool-down phase of the plant, when neither core flooding tanks nor safety injections systems are automatically available. Though fuel rod dryout occurs, the activation of one of four lines of low pressure emergency injection is sufficient to re-establish reliable core cooling. In the cooling-down situation, the primary circuit is pressurised with nitrogen, therefore, non-condensable gas can enter the primary circuit from the pressurizer during the blow-down phase. The transport of the nitrogen along the primary circuit was studied with a novel type of a local void probe equipped with an integrated micro-thermocouple. RELAP5 was found to be able to predict the behaviour of the non-condensable gas in the primary circuit. Despite of some delay in the prediction of the time of the appearance of the gaseous phase in the begin of the process, most details of the transient were well reproduced by the code.