bluuebunny/crossref_metadata_2025_split huggingface dataset:
Upgrading of an Ultrasonic Fatigue Testing Machine by Means of Early Stage Damage Detection
Authors: Kovacs Stephan , Stille Sebastian , Ernstes Daniel , Beck Tilmann 
Published: December 2013

Abstract
This contribution highlights the implementation of different methods for early stage damage detection in very high cycle fatigue (VHCF) experiments by means of an ultrasonic testing machine developed by BOKU in Vienna. Basically three different methods are used for in-situ evaluation of degradation: the analysis of (i) the harmonics, (ii) the development of the resonance frequency, (iii) the damping behaviour of the specimen at the end of each testing pulse. The fatigue experiments and measurements of the relevant parameters are controlled using the software LabView. We demonstrate the sensivity of the different methods on two specimen variants: (i) round samples of the chromium steel X10CrNiMoV12-2-2 and (ii) flat samples of the aluminium alloy Al-2024.
Assessment of Fracture Behaviour under Impact Loading with Simultaneous Recording of Acoustic Emission
Authors: Schoßig Marcus , Bierögel Christian , Grellmann Wolfgang 
Published: December 2013

Abstract
The objective of this paper is the assessment of the toughness of glass fiber-reinforced polypropylene and polybutene-1 by means of fracture mechanics concepts to describe the resistance against unstable crack initiation for these materials. In addition, the acoustic emissions during the instrumented Charpy impact test were recorded, which allows the characterization of the damage kinetics. For this purpose, the recorded transient signals of the acoustic sensor were analyzed with the wavelet transform. Thus, it was possible to describe the onset of the damage in the time domain, as well as the load Fs and the corresponding deflection fs. In dependence on the bonding conditions of the materials, the damage onset was detected for polypropylene before and for polybutene-1 at the transition from elastic to elastic-plastic behaviour.
A Crack Identification Approach for Beam-Like Structures under Moving Vehicle using Particle Swarm Optimization
Authors: Gökdağ Hakan 
Published: December 2013

Abstract
A crack identification method for beam type structures under moving vehicle is proposed. The basic of the method is to formulate damage detection as an inverse problem, and solve for damage locations and extents. With respect to this, an objective function is defined based on the difference of damaged beam dynamic response and the response calculated by the mathematical model of the beam. The optimization problem is solved by the particle swarm optimization (PSO) with linearly increasing inertia weight to obtain crack locations and their depths. By the numerical simulations, it was observed that cracks with depth ratio of 0.1 can be identified with reasonable error by the present method in spite of noise interference of 3 %.
Low Frequencies for Cardboard Quality Assurance
Authors: Ebersold Zoran , Mitrović Nebojša , Đukić Slobodan , Peulić Aleksandar , Obradović Dragiša 
Published: December 2013

Abstract
During the ultrasound defectoscopy the ultrasound absorption factor inside the material is raised to the fourth power of frequency. In conjunction with the previously stated, the attenuation of the sound signal which is caused by the reflections of the sound inside the sample, the application of high frequency ultrasound in porous and hollow materials is very limited or even impossible. The frequencies are the reason for this, because they are in the range of just several megahertz, which are currently the main trend in the ultrasound examination. This paper presents a principle of this new method, including the experimental results from its application on the typical represent of product packaging material. Also, it is shown that the expressed absorption of ultrasound waves from porous and hollow structures can be avoided by applying the method with such low frequencies.
Effects of Surface Treatment on Corrosion Resistance of 316 Stainless Steel Implants in Tyrode Solution
Authors: Ahmadian Zeinab , Danaee Iman , Golozar Mohammad Ali 
Published: December 2013

Abstract
The effect of different surface preparation methods such as mechanical, chemical, and electrochemical surface preparation as well as ultrasonic cleaning on the formation, stability, and deterioration of surface films formed on austenitic 316 stainless steel was investigated in Tyrode's solution. The methods of cyclic polarization, AC impedance measurements and surface techniques were used. A hysteresis loop in a cyclic polarization curve was obtained that indicates a delay in re-passivation of an existing pit when the potential is scanned cathodically. Nyquist diagrams consist of two strongly overlapped capacitive semicircles which are assigned to charge transfer and passive film resistance. Electrolytic polishing improves corrosion resistance by increasing the value of the corrosion potential and breakdown potential of the passive layer as well as the pit initiation potential. After chemical passivation and acid cleaning, no perfect passivation region was observed. Change in surface fractal is in good agreement with the result obtained from height roughness factor of AFM.
Direct Decomposition of N2O Emitted from Nitric Acid Plant Tail Gases Using Noble Metal Supported Mordenite-Zeolite Catalysts∗
Authors: Kwon Byung-Chan , Cho Sung-Su , Seo Minhye , Lee Sungkyu , Song Jinho 
Published: December 2013

Abstract
Mordenite based catalysts for direct decomposition of N2O have been successfully prepared and their direct decomposition performance characterized at the operating temperature of 300–400 °C commonly encountered in the nitric acid plants tail gases. The catalyst was prepared in 2 steps: 1. Precursor wet ion exchange, 2. Precursor impregnation. In addition to the previous contribution, it is shown here that the bimetallic Rh-, Pd-, Ir-Fe-MOR catalysts thus prepared exhibited an excellent N2O decomposition performance: total conversion efficiency of Rh-Fe-MOR catalyst has been achieved at 400 °C and between 7500 h−1 and 10 000 h−1 space velocity.
A Numerical Study on the Mechanical Properties and the Processing Behaviour of Composite High Strength Steels
Authors: Münstermann Sebastian , Vajragupta Napat , Weisgerber Bernadette , Kern Andreas 
Published: December 2013

Abstract
The demand for lightweight construction in mechanical and civil engineering has strongly promoted the development of high strength steels with excellent damage tolerance. Nowadays, the requirements from mechanical and civil engineering are even more challenging, as gradients in mechanical properties are demanded increasingly often for components that are utilized close to the limit state of load bearing capacity. A metallurgical solution to this demand is given by composite rolling processes. In this process components with different chemical compositions were jointed, which develop after heat treatment special properties. These are actually evaluated in order to verify that structural steels with the desired gradients in mechanical properties can be processed. A numerical study was performed aiming to numerically predict strength and toughness properties, as well as the processing behaviour using Finite Element (FE) simulations with damage mechanics approaches. For determination of mechanical properties, simulations of tensile specimen, SENB sample, and a mobile crane have been carried out for different configurations of composite rolled materials out of high strength structural steels. As a parameter study, both the geometrical and the metallurgical configurations of the composite rolled steels were modified. Thickness of each steel layer and materials configuration have been varied. Like this, a numerical procedure to define optimum tailored configurations of composite high strength steels could be established.
The Effects of Process Parameters on the Recycling Efficiency of Used Aluminium Beverage Cans (UBCs)
Authors: Ozer Gokhan , Yuksel Caglar , Comert Zekeriya Yasar , Guler Kerem Altug 
Published: December 2013

Abstract
In this paper, the effects of process parameters on the recycling efficiency of used aluminium beverage cans (UBCs) were investigated. In the experimental studies, separated internal workshop scraps and used aluminium beverage cans are used as charge materials for melting process. Aluminium beverage cans are thin walled parts and produced with high Mg content aluminium alloys. Thus its high oxidation affinity reduces recycling efficiency of the cans. Used can pieces were pressed to obtain briquettes for charging. To increase the recycling efficiency and to optimize the process conditions, preheating, pre-charging, and fluxing were applied. The optimum parameters that provide the maximum recycling efficiency were determined. Chemical analyses and tensile tests were carried out with the resulting as cast samples.
Processing of Finely disseminated Saudi Iron Ores
Authors: Ahmed Hussin A. M. , Mahran Gamal M. A. 
Published: December 2013

Abstract
Iron ores located in Alswaween area, Saudi Arabia are of finely disseminated nature. They require ultrafine grinding for a considerable degree of liberation. In this paper, different upgrading techniques are described for their processing. The applied upgrading techniques included selective flocculation and column flotation as recent efficient technologies in fines upgrading. Each technique was investigated and optimized separately. Results showed that neither selective flocculation nor column flotation can be successfully used alone to produce high quality iron concentrate, especially when using iron ore of size fraction 0.075 mm (100 %). The best quality concentrate was found to have 55 % Fe and 57 % Fe when applying selective flocculation and column flotation, respectively, at their optimum operating conditions. Meanwhile, the previously obtained results can be significantly improved when grinding the ore < 45 µm first and applying selective flocculation as cleaning step for the concentrate obtained from the column flotation. Thus, it is possible to obtain a concentrate having an iron content of 63.55 % Fe with 52.3 % yield which means an iron recovery in the concentrate of about 80 %.
The Effect of Helical Pin Profiles on the Friction Stir Welding Performance of Aluminium Alloy AA6082
Authors: Kasman Şefika 
Published: December 2013

Abstract
In this study, one of the solid state welding methods, friction stir welding, was studied with the AA6082 aluminum alloy. Two types of pins with a special geometry were used to investigate the effect of pins profile, tool rotational speed, and welding speed on the mechanical properties of welded joints. The pin profile was associated with weld joint properties such as tensile strength, elongation, bending strength, bending force, hardness distributions and temperature. Results have shown that the friction surface area of the pin has a significant role on the mechanical behaviour of the joint. The results of tensile tests associated with the pin profile indicate that the helical two-flute pin has a high tensile strength and elongation compared to the helical four-flute pin. Discrepancies in the tensile strength of the welded samples of the two pin profiles have been found between 37–55 % at the same welding conditions. Despite the relatively poor static properties, the helical four-flute pin has better bending properties. Higher bending strength and force (260.634 MPa and 347.513 daN) were obtained at test conditions of 2000 rpm and 100 mm/min. Bending without any defect on the joint was achieved at 2000 rpm and 200 mm/min. The effect of welding parameters on the hardness profile was not clear, and it has been observed that, in comparison, the helical two-flute pin did not create a remarkable difference with regard to hardness.
Characterization of Sigma Phase in Duplex Stainless Steels Using Non-destructive Ultrasonic Techniques
Authors: Rodriguez Cristina , Biezma Victoria , Fernandez Monica 
Published: December 2013

Abstract
Duplex stainless steels have wide applications in industry due to their high mechanical strength, excellent toughness, and high corrosion resistance regarding to other types of steels. However, these steels are susceptible to form brittle phases during heat treatment associated to manufacture or welding processes, in particular the negative effect of sigma-phase into ferrite-austenitic microstructure has to be pointed out. In this work, a study is carried out about the use of ultrasonic nondestructive technique to establish a relationship between sigma phase signal percentages in 2507 duplex stainless steel and more relevant features of the collected ultrasonic signal in an equation. Thus, a novel method is obtained to perform the inspection of these materials in-situ in order to avoid the loss of mechanical resistance and to increase the susceptibility to localized corrosion in service.
Investigating the Wear Behaviour of FeCrC/B4C Powder Alloys Coating Produced by Plasma Transferred Arc Weld Surfacing Using the Taguchi Method
Authors: Gür Ali Kaya 
Published: December 2013

Abstract
In this study, the optimization of the abrasive wear behaviour of a medium carbon steel surface with a FeCrC/B4C powder coating applied by using the plasma arc weld surfacing process is examined. Optimization of the process parameters represents the key step in the Taguchi method to achieve high quality without increasing cost. The Taguchi method uses orthogonal arrays to maximize the effect of controllable parameters and to minimize the effect of uncontrollable process para­meters. The abrasive wear behaviour of the surface of a medium carbon steel substrate material coated with FeCrC and with 15 % or 25 % B4C was tested at loads of 10 N, 20 N, and 30 N and at distances of 10 m, 20 m, and 30 m. The lowest wear loss, representing the most important criterion in determining the wear behaviour, was optimized with the so-called lowest-the best control characteristics of the Taguchi method and the results were analyzed by graphical methods.
Mathematical Modeling of Diameter and Circularity Deviation in Wire Electrical Discharge Machining of a Hot Work Tool Steel
Authors: Esme Ugur , Kulekci M. Kemal , Akkurt Adnan , Seker Ulvi , Ozkul Iskender 
Published: December 2013

Abstract
The suitable selection of manufacturing process and conditions are very important in manufacturing processes to obtain good surface quality and dimensional precision. Thus, it is required to know properties relating to material, surface quality and dimensional precision by means of mathematical models which allow some predictions taking into account operation conditions such as feed rate, current and pulse on time, etc. Wire electrical discharge machining (WEDM) represents a modification of electro discharge machining (EDM) and is widely used for a long time for cutting punches and dies, shaped pockets as well as other machine parts on conductive work materials. Present work is focused on the regression modeling predicting diameter and circularity deviation of a hot work tool steel. Mathematical relationships between circularity and diameter deviation as well as WEDM cutting parameters (feed rate, current and pulse on time) have been investigated. Results show that, regression analysis can be successfully applied for this mathematical model.
Bewertung der Schwingfestigkeit von Schweißnahtenden mit dem Kerbspannungskonzept und bruchmechanischen Methoden∗
Authors: Waterkotte Ralf , Baumgartner Jörg , Ai Qingfeng 
Published: December 2013

Abstract
In dieser Arbeit wurde eine Bewertungsmethodik untersucht, mit der das komplexe Versagensverhalten von geschweißten Verbindungen beschrieben werden kann. Die Bewertung erfolgt dabei auf Basis eines Zwei-Phasen-Modells, in dem die Berechnung der Anrisslebensdauer und der Rissfortschrittslebensdauer getrennt durchgeführt wird. Die Anrisslebensdauer wird basierend auf dem Kerbspannungskonzept mit Spannungsmittelung nach Neuber sowie der Theorie des kritischen Abstandes nach Taylor berechnet. Die Makro-Rissfortschrittslebensdauer wird ausgehend von FE-Analysen unter Verwendung von bruchmechanischen Kennwerten bestimmt. Die untersuchten Methoden lieferten bei der Abschätzung der Anrisslebensdauer gute Ergebnisse. Beim Vergleich der berechneten Spannungsintensitätsfaktoren zeigen sich Unterschiede in Abhängigkeit von den verwendeten Berechnungsansätzen. Es zeigte sich, dass die eingesetzten Methoden für den industriellen Einsatz weiter verbessert werden sollten.
Evaluation of the Cold Formability of Multiphase Steels by Damage Mechanics Approaches∗
Authors: Münstermann Sebastian , Lian Junhe , Vajragupta Napat 
Published: December 2013

AbstractDuring sheet metal forming of multiphase steel for automotive application, more and more often failure happens prior to necking, so that the forming limit diagram is not an appropriate measure for cold formability anymore. Alternatively, the modified Bai Wierzbicki (MBW) model can be applied since it belongs to the group of coupled continuum damage mechanics models. It considers all invariants of the stress tensor both in the yield potential and in the crack initiation criterion. In this publication the model is successfully applied to characterize the cold formability of a dual phase steel of the grade DP600. Additionally, a procedure is described which delivers the parameters of the macroscopic MBW model's damage initiation criterion by simulations of representative volume elements. In these simulations, the underlying physical mechanisms of crack initiation and propagation are quantitatively described.
Plättchen-Biegeversuch nach VDA 238-100∗
Authors: Neuhaus Ralf , Borsutzki Michael 
Published: December 2013

Kurzfassung
Zur Ermittlung der Versagensanfälligkeit von metallischen Werkstoffen bei Biege-Umformprozessen sowie von Kennwerten zur numerischen Simulation des Verformungsverhaltens dient der sogenannte Plättchen-Biegeversuch. Als Kennwert dient der beim Anriss der Probe herrschende Biegewinkel, der in der Regel aus dem aufgenommenen Stempelweg und der Geometrie der Prüfanordnung rechnerisch ermittelt wird. Bei ThyssenKrupp Steel Europe ist hierzu ein neuartiges optisches Winkelmesssystem im Einsatz, das zeitlich synchronisiert mit dem Kraft-Weg-Verlauf der Maschine den Biegewinkel kontinuierlich und direkt an der Probe bestimmt. Durch den Vergleich berechneter und gemessener Biegewinkelverläufe wird gezeigt, dass insbesondere bei Biegewinkeln über 90° deutliche Unterschiede in den Prüfergebnissen auftreten.
Prüftechnik in der Kupferhalbzeugindustrie∗
Authors: Theobald Stefan , Hofmann Uwe , Riedle Joachim 
Published: December 2013

Kurzfassung
Die technologischen Eigenschaften von Halbzeugen aus Kupfer und Kupferlegierungen hängen neben der chemischen Zusammensetzung auch von den Parametern der thermo-mechanischen Herstellprozesse ab. Mess-, Prüf- und Regeltechnik dient dabei neben der Überprüfung der Qualität vor allem der Prozessoptimierung. Nach einem Überblick der üblicherweise zum Einsatz kommenden Prüftechnik werden vor allem anwendungsspezifische Prüfverfahren erläutert. Exemplarisch werden die Kontaktwiderstandsmessung an Steckverbinderwerkstoffen sowie Geräte zur Bestimmung der Biegewechselfestigkeit von Drähten in Seewasseratmosphäre vorgestellt. Zur Bestimmung des Umformvermögens der Werkstoffe ist die Messung der Fließkurve (auch temperatur- und geschwindigkeitsabhängig) von Bedeutung. Ein dafür selbst entwickelter Torsionsplastometer-Messplatz wird mit Anwendungsbeispielen beschrieben.
Application of Genetic Algorithms (GA) for the Optimization of Riveted Joints
Authors: Baskal Tamer , Nursoy Mustafa , Esme Ugur , Kulekci Mustafa Kemal 
Published: December 2013

Abstract
Genetic algorithms have an effective search technique in a predefined research space based on natural selection theory. They use the same combination of selection, recombination, and mutation to evolve a solution to a problem. In this study, it has been demonstrated how to determine the optimal diameter, sheet thickness, and sheet width in riveted joints by means of genetic algorithms (GA). In this study the optimization of objective function for the variables in predetermined limit ranges was applied. Since the algorithms developed by this way are based on a principle to find out the best within a range like genetic process, it is becoming possible to predict the most suitable values for riveted junction dimensions in the defined limit range. The algorithms were restrained considering rivet diameter, thickness and width of the sheet, shear strength, tensile strength, and tear hazard of the sheet.
Röntgenrückstreuradiografie – Eindringen statt Durchdringen, aber Bilder mit Schatten
Authors: Wrobel Norma , Kolkoori Sanjeevareddy , Osterloh Kurt 
Published: December 2013

Kurzfassung
Der große praktische Vorteil der Rückstreuradiografie allgemein ist, dass kein Bilddetektor am Objekt auf der der Strahlenquelle gegenüberliegenden Seite aufgestellt werden muss. Dieses ist immer dann gegeben, wenn sich das Untersuchungsobjekt in oder an einer Wand befindet oder es so groß ist, dass eine Durchstrahlung aufgrund der zu durchdringenden Schichtdicken nicht infrage kommt. Von der üblichen Methode, das Objekt mit einem wandernden ausgeblendeten Einzelstrahl („Bleistiftstrahl“) abzutasten und die gesamte rückgestreute Strahlung großflächig zu registrieren, unterscheidet sich das hier verwendete Verfahren grundsätzlich. Das Objekt wird voll von einem (unkollimierten) Kegelstrahl angestrahlt. Das Bild wird mit einer Kamera aus absorbierendem Material (Wolfram, Blei) aufgenommen, die einen Matrixdetektor als Bildempfänger enthält. Die „Optik“ besteht aus einer besonders geformten Schlitzblende, die nach einem erweiterten Lochkameraprinzip arbeitet, das auch dickere Blendenmaterialschichten zulässt. Die voneinander unabhängige Positionierung von Kamera und Strahlenquellen erlaubt unterschiedliche Einstrahlgeometrien, die verschiedene Ergebnisbilder liefern. So erscheint ein komplexer Gegenstand vor einer rückstreuenden Wand völlig anders, als wenn er frei im Raum steht. Röntgenrückstreubilder müssen deshalb abhängig von ihrer „Ausleuchtung“ mit der Röntgenstrahlung und näheren Umgebung interpretiert werden.
Surface Roughness Changes on β-Titanium Orthodontic Wires after Corrosion in Various Artificial Saliva Solutions
Authors: Kucukyildirim Bedri Onur , Eker Aysegul Akdogan 
Published: December 2013

Abstract
β-Titanium orthodontic wires are exposed to three different artificial corrosive environments, modified Fusayama, modified Fusayama with 0.1 % NaF addition, and modified Fusayama with 1.7 % H3PO4 addition, which are similar to the oral cavity conditions. Corrosion behaviours of wires are observed by using weight loss method and scanning electron microscope observations. Afterwards, surface roughness of wires is investigated in details. Consequently, it is determined that corrosion rate of β-titanium wires exposed to the modified Fusayama solutions with H3PO4 addition is higher because of the acidity of this saliva. Furthermore, maximum increase in surface roughness and skewness are observed in the same environment. Hydrogen embrittlement of titanium is also an important factor for the corrosion of wires.
Experience with MTR fuel at the HOR reactor
Authors: Verkooijen A. H. M. , de Vries J. W. 
Published: December 2013

Abstract
In the last three years 3 events were observed in which the release rate of fission products from the fuel plates into the pool water increased significantly. Although intervention levels laid down in the permit and safety analysis were never reached, the ALARA principle was the incentive to analyse the situation and take appropriate actions.