bluuebunny/crossref_metadata_2025 huggingface dataset:
Kundenrelevante Betriebslasten*
Authors: Pötter Kurt , Till Reinhold , Horst Markus
Published: December 2013

Kurzfassung

Zur Ermittlung von Daten zur Fahrzeugbeanspruchung stehen verschiedene Verfahren zur Verfügung. Die Nutzung von Servicedaten ermöglicht statistische Beanspruchungsanalysen zur Anforderungsoptimierung, die mit kleinen Stichproben nicht möglich sind.
Einsatz virtueller Prüfstände zur Auslegung und Bewertung von Achserprobungen*
Authors: Weigel Nicolas , Weihe Stefan , Jung Gerald , Möller Riccardo , Bruder Thomas
Published: December 2013

Kurzfassung

Virtuelle Prüfstandsmodelle können insbesondere bei der Bewertung physikalischer Erprobungen, der Ableitung vereinfachter Erprobungskonzepte sowie der Signalgenerierung einen wesentlichen Beitrag zu Qualität und Effizienz in der Betriebsfestigkeitserprobung leisten. Der vorliegende Beitrag beschreibt den Aufbau eines Modells eines 13-DOF-Prüfstands für Nutzfahrzeugachsen zur Simulation des Gesamtsystems Prüfstand/Achse. Prüfstandsaktuatorik, Achshaltesystem und Achse sind als Mehrkörpermodell dargestellt. Hydraulik und Regelung werden als Co-Simulationsmodell integriert. Insbesondere wird auch auf die Validierung der Modelle von Prüfstand und Achse aufgrund von Messungen sowie auf die Anforderung an den Detaillierungsgrad der Achsmodelle eingegangen.
Effect of Casting Method of AZ91 D Magnesium Alloy on the Degradation Behaviour in Simulated Body Fluid
Authors: Akca Cem
Published: December 2013

Magnesium-based alloys as biodegradable orthopedic implants have been successful for their high degradation rates in the physiological environment and the consequent loss in the mechanical integrity. Casting method used in production of magnesium-based alloys influences the microstructure of implants due to cooling conditions. In this study, the effects of casting method (permanent mold casting and sand mold casting) on the degradation of AZ91D magnesium alloy in Hank's simulated body fluid at 36.5 ± 0.5°C have been investigated using immersion technique of cylindrical specimens. The specimens were subjected to simulated body fluid for 8 h and 24 h. The results have shown that the cooling rate from melt and grain size have great influence on the degradation rate of magnesium alloy.
Surface Quality and Dimensional Accuracy of Gypsum Bonded Investment Flask Casting Moulds
Authors: Guler Kerem Altug , Cigdem Mustafa
Published: December 2013

In this study surface finish and dimensional charactersitics of castings produced with gypsum bonded block investment moulds were investigated. Commercial and laboratory made gypsum bonded investment moulds were used for investment casting mould making. To compare the casting quality of the investment powders, wax patterns for surface roughness specimens and linear dimension measurement specimens were designed and produced with special geometry. Wax trees were assembled with these patterns, cylindrical stainless steel perforated flasks were settled around the trees and gypsum bonded investment slurries were filled into flasks. Conventional tin bronze and sterling silver were subsequently cast into these moulds by vacuum assisted and vacuum pressure casting processes, respectively. Afterwards, surface roughness of specimens were measured and linear dimensions of wax patterns and cast specimens were compared to determine percentage of dimensional change.
Numerical Optimization of Dental Implant Through the Concept of Functionally Graded Materials
Authors: Hedia Hassan S.
Published: December 2013

The merge of materials science with the biological sciences has produced some advanced materials which are called functionally graded materials (FGMs) in order to provide the desired material characteristics. The FGMs concept originates in Japan in 1984 during the space plan project. FGMs are materials or structures in which the material properties vary with location in such a way as to optimize some functions of the overall FGMs.

It is well known that the main inorganic component of natural bone is hydroxyapatite (HAP) and that the main organic component is collagen (Col). Hydroxyapatite HAP implants are not bioabsorbable, and because induction of bone into and around the artificially made HAP is not always satisfactory, loosening or breakage of HAP implants may occur after implantation in the clinical application. The development of a new material which is bioabsorbable and which has osteoconductive activity is needed. Therefore, the aim of the current investigation is to design an implant, in the presence of cancellous bone as a thin layer around it, from functionally graded material. In this study, a novel biomaterial, collagen/hydroxyapatite (Col/HAP) as a functionally graded material (FGM), was developed using the finite element and optimization techniques which are available in the ANSYS package. These materials have a self-organized character similar to that of natural bone. The investigations have shown that the maximum stress in the cortical bone and cancellous bone for the Col/HAP functionally graded implant has been reduced by about 40% and 19% respectively compared to currently used titanium dental implants.
A Novel Approach for Quantitative Measurement of the Slag Penetration Area in Refractories by Using Computer Aided Image Analysis
Authors: Kurban Cem Emre , Erzi Eray , Yilmaz Suat
Published: December 2013

The Crucible Method is a standard method to determine the corrosion between slag and refractory. According to this method refractory samples are heated to experimental temperature with the active slag powder inside the crucible. The aim of the experiment is to corrode the refractory by slag penetration and cutting the refractory to analyze the corroded surface to determine the slag-refractory interaction. In this study, this method was used and supported by a computer aided surface analyze system which recently has several application areas in material science. The image of the corroded surface of the refractory was transferred to a computer. Image settings and calibrations of complex shaped slag penetration areas were done by Photoshop. Quantitative analysis was done by MVH-ImagePCv7 image analysis software. It was found that the qualitative and quantitative analysis of the Crucible Method was enhanced by the help of computer aided surface display and image analysis techniques.
Einfluss der Mikrostruktur auf den Druck- und Zug-E-Modul teilkristalliner Kunststoffe
Authors: Michaeli Walter , Baranowski Thomas , Kalinka Gerhard
Published: December 2013

Kurzfassung

In Kooperation zwischen dem Institut für Kunststoffverarbeitung (IKV) und der Bundesanstalt für Materialforschung und -prüfung (BAM) wurde das mechanische Verhalten unter Druck- und Zugbelastung unterschiedlicher morphologischer Strukturen teilkristalliner Thermoplaste (PP und POM) untersucht. Im Ergebnis steigt der E-Modul sowohl der druck- wie auch zugbelasteten Prüfkörper aus spritzgegossenem PP und POM mit gröberem Gefüge an. Probekörper mit scherinduziertem Gefüge zeigen einen hohen Einfluss des Kristallisationsgrads auf den E-Modul.
The Investigation of Graphite Distribution on Diffusion Bonding of the AISI 1030 Low Carbon Steel with Nodular Cast Iron
Authors: Caligulu Ugur
Published: December 2013

The joining of Nodular Cast Iron with the conventional methods presents many problems due to the presence of high carbon content and low ductility. Therefore it is necessary to use heat treatment or to take some precautions before and after bonding. In this study, the graphite distribution on both sides of the interface of diffusion bonding of the AISI 1030 low carbon steel with Nodular Cast Iron was investigated. In order to observe the behavior of the graphite nodules in diffusion bonding, AISI 1030 was used as the comparison of alloy. Diffusion bonding experiments were carried out in an argon atmosphere at the temperatures of 900–950 and 1000 °C and 15 MPa under a dynamic load for 50–100 and 150 min. holding times. The properties of microstructure and graphite distribution that formed in the interface zone of the joints were examined by optic microscope, SEM, EDS, and X-Ray analysis. The hardness values from the interface were measured with the HV hardness scale. The strength of the joint was tested by lap-shear tests. The result of all observations indicated a homogenous graphite distribution. On the other hand, as a function of the process temperature elevation, an increase in the amount of graphite atoms that migrated towards the interface and a decrease in the nodule diameters were observed.
Structural Health Monitoring (SHM) – Konzepte zur Lebensdauerverlängerung und zur Gewichtsreduktion*
Authors: Büter Andreas , Hanselka Holger
Published: December 2013

Kurzfassung

Die ständig steigenden Forderungen zu immer leichteren Konstruktionen können mit den derzeitigen Auslegungsphilosophien nur bis zu einem bestimmten Maß realisiert werden. Damit diese Grenze überschritten werden kann, müssen zukünftig Überdimensionierungen vermieden werden. Die Betriebssicherheit zukünftiger Strukturen darf durch veränderte Auslegungsphilosophien, Wartungs- und Inspektionsintervalle natürlich nicht negativ beeinflusst werden. Durch den Einsatzvon strukturintegrierten Überwachungssystemen, wie z. B. SHM-Systemen, ergeben sich viele Vorteile für eine erweiterte technische und wirtschaftliche Ausnutzung von Leichtbaustrukturen. Diese Systeme haben das Potenzial, die Betriebssicherheit effizienter zu gewährleisten, erhöhen aber die Anforderungen an die Zuverlässigkeit des Gesamtsystems.
Prävention von Korrosion in regenerativen Kraftstoffen*
Authors: Troßmann Torsten , Eppel Klaus , Wagner Katharina , Berger Christina , Oechsner Matthias
Published: December 2013

Kurzfassung

Zur Reduktion der CO2-Emissionen kommen im Straßenverkehr vermehrt Kraftstoffe bzw. Kraftstoffkomponenten biogenen Ursprungs zum Einsatz. Diese Beimischungen verändern die bisherigen Eigenschaften der Kraftstoffe. Es treten bei metallischen Werkstoffen unterschiedliche Formen der Korrosion auf, wie elektrochemische Korrosionsarten infolge Wasseraufnahme und die chemische Alkoholatkorrosion. Aussagefähige Prüfmethoden und Einrichtungen zur Nachbildung der in Biokraftstoffen möglichen Korrosionsarten wurden durch gemeinsame Anstrengungen der deutschen Automobilindustrie, deren Zulieferindustrie und des Instituts für Werkstoffkunde entwickelt [1]. Neben der Bewertung des Korrosionsverhaltens von Werkstoffen bzw. Beschichtungen in biogenen Kraftstoffen tragen diese Verifikationsansätze in Ergänzung zu grundlegenden Untersuchungen zum Verständnis der für die Degradation wesentlichen Vorgänge bei und dienen zur Prävention von durch Korrosion verursachten Schäden.
Fatigue and Aircraft In-Service*
Authors: Schmälzle Ulrich
Published: December 2013

Two aspects are considered in the present contribution: Highlights are shown considering the preparation of inspection and maintenance programs and the influence of these programs is outlined. In the second part of this paper the structural evaluation of aircrafts is demonstrated which are in-service and are associated to respective incidents.
Schlagversuche an ultrahochfestem Beton – Charakterisierung der Dehnungen und der Ultraschallgeschwindigkeiten
Authors: Leonhardt Sandy , Lowke Dirk , Stengel Thorsten , Gehlen Christoph
Published: December 2013

Kurzfassung

In diesem Beitrag werden Schlagversuche vorgestellt, die an ultrahochfestem Beton (engl. Ultra High Performance Concrete – UHPC) als Werkstoff für Rammpfähle im Tiefbau durchgeführt wurden. Ein Rammversuch mit praxisnahen Probekörperabmessungen diente zur ersten Einschätzung der auftretenden Dehnungen am UHPC. Aufbauend auf dem praxisnahen Rammversuch wurden weitere Versuche mit laborüblichen Probekörperabmessungen und unterschiedlichen UHPC-Zusammensetzungen mit Stahlfasern durchgeführt. Die Untersuchungsergebnisse zeigten eine Abhängigkeit vom eingesetzten Stahlfasertyp und des Fasergehaltes.
X-Ray Tests of AISI 430 and 304 Stainless Steels and AISI 1010 Low Carbon Steel Welded by CO2 Laser beam welding
Authors: Taskin Mustafa , Elazig Ugur Caligulu , Turkmen Mustafa
Published: December 2013

For this study, X-Ray radiographic tests of AISI 430 and 304 stainless steels with AISI 1010 low-carbon steels welded by CO2 Laser beam welding (LBW) have been performed. Laser beam welding experiments were carried out under argon and helium shielding gas, at 2000–2250 and 2500 W heat input and 100-200-300 cm/min welding speeds. After this process, the radiographic tests of the welded joints were performed by X-Ray diffraction. The result of the radiographic tests indicated that with increasing heat input the widths of the deep penetration increased in all specimens. On the contrary, by increasing the welding speeds the widths of the deep penetration decreased. The best properties of the AISI 430 and 304 stainless and AISI 1010 low-carbon steel welds were observed at the specimens welded at 2500 W heat input and 100 cm/min welding speed.
Lebensdauerbewertung von thermo-mechanisch belasteten Gusseisen-Zylinderköpfen
Authors: Leidenfrost Marc , Werner Ewald , Meyer Dietrich
Published: December 2013

Kurzfassung

Deutlich gestiegene mechanische und thermische Belastungen in modernen Dieselmotoren erfordern eine detaillierte Betrachtung der dadurch verstärkt gefährdeten Bauteile, wie z. B. der Zylinderköpfe. Die Gefährdung ergibt sich hier neben den gestiegenen Spitzendrücken aus der höheren thermomechanischen Ermüdung (TME), die je nach Werkstoff die Lebensdauer des Bauteils stark beeinflusst. Zur Beurteilung dieser Beanspruchung kommt neben aufwendigen Thermoschock-Motorenversuchen die numerische Simulation (Finite-Element-Methode) zum Einsatz. Für quantitative Aussagen sind die Ergebnisse der numerischen Simulation mittels experimenteller Versuche (Bauteil- und Motorenversuche) zu verifizieren. Der vorliegende Beitrag beschreibt die Vorgehensweise zur realitätsnahen Nachrechnung eines durchgeführten Thermoschock-Bauteilversuchs mit Einzelzylinderköpfen sowie die in der Nachrechnung verwendeten mathematischen Werkstoff- und Lebensdauermodelle. Die berechneten und experimentell erhaltenen Ergebnisse zur Bestimmung der Lebensdauer werden einander gegenübergestellt und diskutiert.
Performance of Automotive Composite Bumper Beams and Hood Subjected to Frontal Impacts
Authors: Jalauddin Mai Nursherida , Ali Aidy , Sahari Barkawi , Aziz Nuraini Abdul
Published: December 2013

Performance of automotive composite bumper beam subjected to frontal impact is presented and discussed in this paper. The aim of this study is to analyze the effect of steel and composite materials on internal energy of the automotive front bumper beam and with respect to pedestrian head injury at the hood. The front bumper beams and hood made of aluminum AA5182, e-glass/epoxy composite and carbon epoxy composite were studied and characterized by impact modeling using LS-DYNA V971, according to United States New Car Assessment Program (US-NCAP) defining the frontal impact velocity and based on European Enhanced Vehicle-Safety Committee. The most important variables of this structure were mass, material, internal energy, and the so-called Head Injury Criterion (HIC). The results are compared with a bumper beam and a hood made of mild steel. The in-plane failure behaviors of the composites were evaluated by using the Tsai Wu failure criterion. LS-DYNA Finite Element Analysis software was used. The results showed that a carbon fiber/epoxy composite bumper can reduce the bumper mass and has the highest value of internal energy followed by the glass fiber/epoxy composite. The FE model of a production hood was introduced and validated. In order to evaluate the protective performance of the baseline hood, the FE models for a 50 percentile of an adult pedestrian dummy were used to impact the hood. It was found that the aluminum AA5182 hood can obviously reduce the Head Injury Criterion (HIC) values compared to the baseline hood. The HIC values of the dummy model were further reduced to much lower than 1000.
Effects of Squeeze Pressure on Microstructure, Porosity and Hardness of an In-Situ Mg2Si/Al–Si–Cu Composite
Authors: Ozer Gökhan , Güler Kerem Altug , Lus Hüseyin Murat
Published: December 2013

The effect of applied pressure on microstructures and properties of an in-situ formed Mg2Si/Al-Si-Cu reinforced metal matrix composite fabricated by squeeze casting are investigated. Due to the wide solidification range and the high viscosity, this type of composites is prone ro shrinkage and gas porosity. In order to improve cast ability and to obtain better properties, the squeeze casting technique has been used. The results showed that primary Mg2Si crystals are formed by adding pure Mg into the hypereutectic Al-Si-Cu alloy (A380). It was found that, with the application of 30 MPa and 40 MPa pressure during solidification, the average size of primary Mg2Si particulates decreases from about 87 µm to about 21 and 18 µm and that the average porosity values of the cast samples is significantly decreased from 8.75 % to 0.50 and 0.35 %, respectively.
Determination of Mechanical Properties and Failure Pressure in Composite Cylinders
Authors: Benli Semih , Özen Mustafa , Sayman Onur , Deniz Mehmet Emin
Published: December 2013

In this study, mechanical properties of cylindrical composite specimens were measured experimentally. Composite cylinders oriented at 0° C and 90° were manufactured by using the hand lay -up technique. The cylinders were loaded axially for measuring the axial tensile strength and compressive strengths. Some specimens were attached to a torsion machine for measuring shear strength and shear modulus. Thus, a close and true measuring was performed in the cylindrical specimens. A finite element solution was performed in closed ended composite cylinders under internal pressure and thermal loading. Thermal stresses occur at low and high temperatures with respect to the room temperature. For a true or close solution in composite cylinders, mechanical properties should be determined in cylindrical composite specimens.
Effect of Nanocomposite Coating with Different Concentrations on the Fatigue Life of Stainless Steel316 with Different Surface Roughness
Authors: Hedia Hassan S. , Aldousari Saad. M. , Abdellatif Ahmed K. , Gadhi Raed Hasan M.
Published: December 2013

Many experimental researches succeeded to improve fatigue properties of materials by treating their surfaces. In this study, the benefits of nanocomposite material are used to investigate the fatigue life of stainless steel specimens with different surface roughness. Nanocomposite coating was prepared with different concentrations (0.3 %, 0.5 %, and 0.7 %) of multi wall carbon nano tubes MWCNT. This coating was applied on stainless steel test specimens with four different values of the surface roughness (0.3, 0.8, 1.6, and 2.5). It turned out that fatigue life increased more than four times compared to the original material when using 0.5 % and 0.7 % MWCNT concentration in coating composition with the 0.3 surface roughness, while no significant difference was detected at another roughness.
Erosion Process of 66 MW Steam Turbine Rotor Blades
Authors: Staniša Branko , Schauperl Zdravko , Šnajdar Mateja
Published: December 2013

Apart from erosion of leading edges, erosion of the rotor blades trailing edges often occurs in condensing steam turbines, due to the impact of wet steam water droplets. Considerable erosion of the rotor blades trailing edges may be more dangerous for a reliable turbine operation than the leading edges erosion. During several years of research many results concerning erosion damage to the trailing edges of 66 MW condensing reduction steam turbine final stage rotor blades at the Thermo-electric power plant – heating plant (TE-TO) Zagreb have been gathered and are presented in this paper. Correlation between the erosion process behavior of the last stage turbine rotor blades trailing edges and the number of operating hours has been established.
Impact Resistance of Armor Composite Made of Kevlar29 and Al2O3 Powder
Authors: Ali Aidy , Abbud Luay Hassim , Talib A. R. Abu , Mustapha Faizal
Published: December 2013

In this study, the impact behavior of a composite material made from Kevlar29 – Al2O3/ epoxy for hard body armor is considered. The present experimental method focused on the behavior of the ballistic limit, energy absorption, and final velocity of flat cylindrical and conical projectiles. The results indicated that the maximum ballistic limit at impact velocity is 400 ±7 m/s for an 18 mm target thickness. Experimental results showed that the best ballistic performance was achieved with composite materials made of Kevlar29 – Al2O3/epoxy. The results concerning the initial and final velocities showed good agreement compared with the Ipson and Recht equation.
Neuartige automatisierte Stangenprüfung mit Ultraschall-Gruppenstrahlern
Authors: Schenk Gottfried , Brackrock Daniel , Dohse Elmar , Ploigt Roy , Deutsch Wolfram
Published: December 2013

Kurzfassung

Wie erkennt man Risse oder Einschlüsse in Stabstahl, bevor daraus beispielsweise eine Automobil-Antriebswelle entsteht? Halbzeug­produkte werden vor der Weiterverarbeitung zerstörungsfrei auf Fehlerfreiheit geprüft, denn nicht erkannte Schäden können teure Rückrufaktionen zur Folge haben. Dieser Beitrag stellt ein Verfahren vor, mit dem die bisherige konventionelle Ultraschallprüfung durch die Gruppenstrahlertechnik ersetzt wird und die Prüfqualität bei gleichzeitiger Beschleunigung des Prüfvorgangs signifikant erhöht werden kann.
Structural Design Optimization of Vehicle Components Using Cuckoo Search Algorithm
Authors: Durgun İsmail , Yildiz Ali R.
Published: December 2013

In order to meet today's vehicle design requirements and to improve the cost and fuel efficiency, there is an increasing interest to design light-weight and cost-effective vehicle components. In this research, a new optimization algorithm, called the Cuckoo Search Algorithm (CS) algorithm, is introduced for solving structural design optimization problems. This research is the first application of the CS to the shape design optimization problems in the literature. The CS algorithm is applied to the structural design optimization of a vehicle component to illustrate how the present approach can be applied for solving structural design problems. Results show the ability of the CS to find better optimal structural design.
Regression Based Neural Network Modeling for Forecasting of the Metal Volume Removal Rate in Turning Operations
Authors: Kahraman Funda , Esme Ugur , Kulekci Mustafa Kemal , Kazancoglu Yigit
Published: December 2013

The present paper focuses on two techniques, namely regression and neural network, for predicting tool wear. Predicted values of tool wear by both techniques were compared with experimental values. Also, the effects of the main machining variables on tool wear have been determined. The metal volume removed (MVR) was taken as response (output) variable and cutting speed, feed rate, depth of cut and hardness were taken as input parameters, respectively. The relationship between tool wear and machining parameters was found out by direct measurement of the tool wear by MVR. The results showed the ability of regression and neural network models to predict the tool wear, accurately.
The Bulky Paper Properties Influence on the Adhesive Bond Strength
Authors: Preprotić Suzana Pasanec , Budimir Ivan , Lajić Branka
Published: December 2013

Adhesive bond strength depends on adherend, adhesive and interphase zone. Adhesive joint includes bonded areas or binding edges across bonded layer. Research of adhesive bond strength focuses on understanding the properties of bulky paper associated with formation of the interphase and adhesive joint failure mode. The key contributors of good adhesive bond strength are paper rough surface necessary for mechanical interlocking, adequate adhesive flow and adaptationfor intimate interaction and acceptable adhesive setting time. Change of parameters has strong influence on final adhesive joint formation. Adhesive bond strength assessment involves adhesive joint strength determination. Pull test method is used for adhesive joint failure mode characterization. Furthermore, adhesive joint strength results directly explain bulky paper bind ability by perfect binding technique. FOGRA recommendation rating directly confirms paperback binding quality with bulky paper application. Understanding of bulky paper bind ability involves comprehensive physiochemical knowledge of material (paper, adhesive). In addition, this binding technique is more unique because of its interest for adhesive joint formation.
Effect of Nanoclay Amount and Compatibilizer Presence on Thermal, Morphological and Mechanical Behaviour of Nanoclay Reinforced Composite Polypropylene Cast Film
Authors: Gocek Ikilem , Adanur Sabit
Published: December 2013

Pure PP film without compatibilizer and nanoclay, nanoclay reinforced PP film without compatibilizer and nanoclay reinforced PP films with compatibilizer were produced to study the effect of nanoclay amount and compatibilizer presence on thermal, morphological and mechanical properties of films. Reinforced films were produced with 1% and 3% nanoclay contents with 3 different compatibilizer amounts to examine if nanoclay addition changes properties of the films in the same manner with different compatibilizer amounts. Melting points of the films slightly increase as the nanoclay content increases. Decomposition temperatures increase, as the nanoclay content increases. As the nanoclay content increases, tensile, burst and tear strengths for the reinforced films decrease. It can be observed that the increase in nanoclay content lowers strain and extension values for reinforced films due to nanoclay dispersion.
Characterization of Au-Ga Alloys with Low Gold Content
Authors: Gomidželović Lidija , Živković Dragana , Talijan Nadežda , Ćosović Vladan , Balanović Ljubiša
Published: December 2013

The results of an experimental investigation of structural, mechanical and electrical characteristics of the alloys in Au-Ga system are presented in this paper. Selected alloys AuxGay (x = 0.1 — 0.3) were examined using light microscopy and SEM-EDX analysis as well as hardness, microhardness and electroconductivity measurements.
Determination of the Minimal Operating Temperature
Authors: Levi Avram
Published: December 2013

According to a new theory poycrystal elements are a comlex self-organized system which gives the possibility to modulate the processes of strengthening by changing temperature within a wide range. An unconventional method for non-destructive determination of the minimal operating temperature (ductile to brittle transition temperature of structural steel TDBTT), based on the results of measuring the speeds of longitudinal and transversal ultrasonic waves and the achieved values of Poisson's ratio, has been developed.
Effect of Heat Treatment Conditions on Microstructure and Mechanical Properties of Long Term Serviced Fe25Cr-35Ni Alloy
Authors: Hemmatad Kannika , Visuttipitukul Patama , Wangyao Panyawat , Lothongkum Gobboon
Published: December 2013

HP alloy Fe-25Cr-35Ni is widely used in petrochemical industry, because of its good corrosion and oxidation resistance at high temperature. As-cast microstructure of HP alloy consists of eutectic carbide in discontinuous network. After service in carburizing atmosphere at high temperature, the microstructure of serviced HP alloy, which consisted of carbide network that was thicker and coarser than as-cast specimens as well as irregular shape carbide, lost its tensile strength and fracture elongation properties. However, the hardness increased. The serviced HP alloys were heat treated in 12 conditions, which could be classified in four main categories. The first one was solutionized at three different temperatures — 1,373, 1,423 and 1,473 K. The second was solutionized at 1,373 K and aged at 1,073, 1,173 and 1,273 K. The third was solutionized at 1,423 K and aged at 1,073, 1,173 and 1,273 K. The last one was solutionized at 1,473 K and aged at 1,073, 1,173 and 1,273 K. The process time for solution was 21.6 ks and aging is 86.4 ks for all conditions. The result showed that the amount of Cr rich carbide vastly decreased after heat treatment in all conditions. The Vicker hardness values (HV) of all heat treated specimen decreased comparing to that of serviced alloy. In conclusion, heat treatment provided new microstructures with lower amount of carbide networks of serviced alloy which resulted in improvement of tensile strength and fracture elongation properties.
Determination of Elastic Plastic Fracture Toughness Parameters for a Compact Tension Specimen Using the Finite Element Method
Authors: Özdemir Uğur , Yeni Çinar
Published: December 2013

In this study, elastic-plastic fracture toughness of an aluminum alloy is investigated. J-integral was calculated using the finite element software and formulation. Crack tip opening displacement (CTOD) is determined by using the plastic hinge model (δph) and direct measurement (δ5). J-Δ a and CTOD-Δ a resistance curves are constructed and compared with those obtained from formulation and those generated from test data, respectively. Good agreement has been obtained between the test results, the formulation and the results of the finite element analysis. The relationship between δph and δ5 is nonlinear and as CTOD increases δ5 becomes larger than δph. The relationship between J-integral and CTOD is found to be linear for both δph and δ5. It has been seen that the proportionality constant dn considerably depends on the method of calculation of CTOD.
Structural Damage Detection Using Modal Parameters and Particle Swarm Optimization
Authors: Gökdağ Hakan , Yildiz Ali R.
Published: December 2013

Vibration based on structural damage detection (DD) is an important subject in many fields of engineering. Detection of possible damage locations before destructive stiffness losses in the engineering structures occur, is a main goal of DD. This paper describes the damage detection in structural elements by means of Particle Swarm Optimization algorithm (PSO). In this regard, the finite element model of a Timoshenko beam is considered, and damage is assumed as a stiffness loss in some elements. Damage locations and extents are identified minimizing some well-known modal parameter based objective functions. It is concluded that modal flexibility is the best among the considered damage indexes. Also, the results show that PSO is an effective optimization approach in structural damage detection.
Examination of Microstructure and Wear Behaviour of a Roller Material Produced by Centrifugal Casting
Authors: Birbaşar Onur , Atapek Ş. Hakan , Türedi Enbiya , Zeren Muzaffer
Published: December 2013

In this study, the microstructure of a roller material produced by centrifugal casting was characterized and its worn surface was examined after wear test. In the first stage of the study, centrifugal casting was used to produce cast iron based roller material. The cross-section of cast matrix was examined using light and scanning electron microscopy after metallographic preparations. In the second stage, ‘ball-on-disc’ type tribometer was used to investigate the wear behaviour of the cast part under dry sliding condition. In order to observe the effect of loading force, the samples were subjected to 10 N, 30 N and 50 N load and the total sliding distance was selected as 500 m. After wear tests, all the worn surfaces were examined using both light and scanning electron microscopy. It is concluded that (i) the roller had pearlitic cast iron matrix having nodular graphite and eutectic carbide, (ii) worn surfaces exhibited typical abrasive and partial adhesive wear tracks, (iii) as the loading force increased the friction coefficient in addition to weight loss of cast iron matrix increased.
Application of Genetic Algorithm (GA) for Optimum Design of Module, Shaft Diameter and Bearing for Bevel Gearbox
Authors: Mendi Faruk , Baskal Tamer , Külekci Mustafa Kemal
Published: December 2013

In this study selection of optimum module, shaft diameter and rolling bearing for conical gear has been done using genetic algorithm (GA). GA, is a novel stochastic method of optimization. GAs are based on the principles of natural selection and evolutionary theory. Objective function was optimized for the design variables between determined boundary values. The GA was constrained by taking into account the power, moment, velocity, wall thickness and bearing distances. Tooth strength and surface crush were considered to be design constraints for module optimization. The other algorithm constraints are maximum bending and torsion moments for shaft optimization, and working life for bearing optimization.
Experimentelle und rechnerische Qualifikation der Vibrationsfestigkeit von elektrotechnischen Großbaugruppen im Lastfall Erdbeben*
Authors: Rödling Steffen , Brettner Bernd
Published: December 2013

Kurzfassung

Einrichtungen zur Übertragung und Erzeugung von elektrischer Energie werden in allen Regionen der Welt errichtet. Auch in solchen, in denen Erdbeben nicht ausgeschlossen werden können oder sogar erwartet werden müssen. Um die Sicherheit der Anlagen zu gewährleisten, ist hier der Nachweis der Standfestigkeit, Integrität und Funktion der Geräte und Komponenten unter erdbebenspezifischen Belastungen erforderlich. Der in der vorliegenden Veröffentlichung beschriebene experimentelle Nachweis an einem Laststufenschalter für Transformatoren wurde bei der IABG mbH, Ottobrunn, durch rechnerische Methoden begleitet und ergänzt. Auf diese Weise wurde ein mit statischen und dynamischen Versuchen abgeglichenes Rechenmodell erstellt, welches bei zukünftigen Qualifizierungen veränderter Baustände herangezogen werden kann. Durch Model-Update werden die so verifizierten Modelle und Methoden angepasst und zur Qualifikation veränderter Typen verwendet.
Optimierter Lebensdauer-Berechnungsprozess von Eisengussbauteilen unter Berücksich-tigung des lokalen Gefüges*
Authors: Hack Michael , Jung Dominik , Egner-Walter Achim
Published: December 2013

Kurzfassung

Der Herstellungsprozess hat in vielen Fällen einen großen Einfluss auf die Betriebsfestigkeit von Bauteilen. Wird dieser vernachlässigt, führt dies im Allgemeinen zu unnötig konservativer Bauteilauslegung und hohen Bauteilgewichten. So wird in der Betriebsfestigkeitsberechnung für Gusseisenkomponenten heute – mangels quantitativer Informationen – meist von homogenen Materialeigenschaften ausgegangen. In diesem Beitrag wird ein durchgehender Berechnungsprozess entlang der Programmpakete Magmasoft – Abaqus – Virtual. Lab Durability vorgestellt, der die erstarrungsbedingt örtlich variierenden Gefügeeigenschaften im Bauteil berücksichtigt. Der Prozess wird exemplarisch an einem Sphäroguss-Bauteil demonstriert.
Surface Properties and Fatigue Life of Stress Peened Leaves
Authors: Savaidis Alexander
Published: December 2013

Experimental results referring to the influence of stress peening treatment on the metallurgical, surface and mechanical properties, especially the fatigue life of parabolic leaf springs made of two high-strength steels, 52CrMoV4 and 51CrV4, are presented. The tested leaves were manufactured under serial conditions. The microstructure, surface roughness, hardness and residual stress profiles as well as Wöhler curves are determined and assessed both in a qualitative and quantitative manner. Compressive residual stresses, increased hardness values and pronounced roughness are determined on the specimens’ stress-peened surface. The experimentally determined Wöhler curves explore the mutual influence of material, surface properties and surface roughness on fatigue behaviour and lifetime. Equivalencies of both raw materials refered to the mechanical properties achieved after the heat treatment and stress peening process are observed.
Bewertung mikrostruktureller Barrieren während der Ermüdungsschädigung von Duplexstählen bei sehr hohen Zyklenzahlen*
Authors: Krupp Ulrich , Giertler Alexander , Marinelli Maria Cecilia , Dönges Benjamin , Knobbe Helge , Christ Hans-Jürgen
Published: December 2013

Kurzfassung

Wechselverformungsexperimente unter Anwendung verschiedener Prüftechniken, wie Servohydraulik, Resonanzprüfmaschinen, Umlaufbiegung und Ultraschall, sowie eine systematische mikrostrukturelle Auswertung der Oberfläche nach vorgegebenen Lastwechselintervallen mithilfe der analytischen Rasterelektronenmikroskopie weisen darauf hin, dass Korn- und Phasengrenzen maßgeblich das Ermüdungsverhalten von Duplexstählen beeinflussen. Je nach räumlicher Orientierung der Gleitsysteme benachbarter Körner und Phasenbestandteile kann die lokale Bildung von Scherbändern erklärt werden, die auch über Grenzflächen hinaus wachsen und schließlich zu Rissinitiierung, Ermüdungsrissausbreitung und Bruch führen.
Einflüsse der Mikrostruktur auf die Ermüdungsschädigung der Aluminiumlegierung EN AC-Al Si7Mg0,3*
Authors: Giertler Alexander , Siegfanz Stephanie , Libally Thomas , Michels Wilhelm , Krupp Ulrich
Published: December 2013

Kurzfassung

In dieser Arbeit sind erste Ergebnisse einer Untersuchung des Einflusses der Mikrostruktur auf die Ermüdungsschädigung der Aluminiumgusslegierung EN AC-Al Si7Mg0,3 zusammengestellt. Hierzu erfolgte zunächst die Herstellung korngefeinter und veredelter Probestäbe durch Abgießen in eine Stahlkokille. Mit gezielten Wärmebehandlungen konnte die Festigkeit des α-Mischkristalls, bei gleicher Größe und Form der eutektischen Phase variiert werden. In den anschließenden Ermüdungsversuchen konnte bei Proben, die bei einer höheren Lösungsglühtemperatur geglüht wurden, eine gesteigerte Lebensdauer festgestellt werden.
Konzept zum Nachweis der Eignung von Härteprüfmaschinen*
Authors: Schenuit Eduard , Altmann Jürgen , Baumann Jürgen , Beisel Peter , Berthold Jürgen , Frenz Holger , Frost Edmund , Horsch Arnold , Rupp Dirk-Michael , Schwenk Dieter
Published: December 2013

Kurzfassung

Der Fachausschuss 3.23 “Härteprüfung” in der VDI/VDE Gesellschaft Mess- und Automatisierungstechnik (GMA) hat Möglichkeiten zur Bestimmung einer Eignung von Härteprüfmaschinen auf Basis der üblichen Methoden bei der dimensionalen Messtechnik geprüft und auch die im Anhang G der ISO 6508-1 vorgeschlagenen Berechnungen zur Messunsicherheit betrachtet. Es wurden Ringversuche an Rockwell- Härteprüfmaschinen durchgeführt und ausgewertet. Auf der Basis der Ergebnisse werden Vorschläge für ein Konzept zum Nachweis der Eignung von Härteprüfmaschinen diskutiert. Unter Eignung einer Härteprüfmaschine wird die Eigenschaft der Härteprüfmaschine verstanden, bei Wiederholungsmessungen unter Laborbedingungen (idealen Bedingungen) Messergebnisse zu erzielen, die einer bestimmten, vorgegebenen Prüfaufgabe (vorgegebene Toleranz) unter Berücksichtigung der Messunsicherheiten genügen.
Formation of Adiabatic Shear Bands in a Tempered Steel under Dynamic Loading and their Damage Effects
Authors: Atapek Ş. Hakan
Published: December 2013

In this study a low alloyed steel was selected and heat treatments including austenization, quenching and tempering were applied to it to obtain a hardened matrix. After heat treatments two steel plates ha-ving hardnesses of 315 and 320 HV were subjected to ballistic shots as target materials. The shots were carried out at 0° from a distance of 30 m to the target materials using API 55-7.62 mm armor piercing projectiles with a velocity of 835–840 m/s. Metallographical and fractographical examinations were carried out after the shots to investigate the behaviour of matrix under dynamic loading and to observe the formation as well as type of adiabatic shear bands and their effects on the nucleation and propagation of cracks within the matrix, in addition to the inclusions. In the etched samples a degenerated matrix compared to the original tempered martensitic-bainitic matrix was observed in the regions close to the penetration. On the other hand deformed and transformed types of adiabatic shear bands were observed as white bands. It is concluded that both types of adiabatic shear bands directly play an important role in the nucleation and propagation of cracks in addition to the inclusions within the matrix.
Effect of Deep Cryogenic Treatment on Mechanical and Tribological Properties of PM S390 MC High-Speed Steel
Authors: Šolić Sanja , Cajner Franjo , Leskovšek Vojteh
Published: December 2013

Application of deep cryogenic treatment instead of conventional heat treatment showed an increase in wear resistance of tools made of high speed steel which are exposed to very complex and demanding conditions in exploitation. The purpose of this study was to investigate the effect of deep cryogenic treatment in combination with plasma nitriding on the tribological properties of powder metallurgy high speed steel, grade PM S390 MC. On treated specimens hardness and fracture toughness was determined, the resistance to intensive adhesive wear (galling) and dry sliding wear (dry sliding wear resistance) were also tested. Test results show that deep cryogenic treatment in combination with plasma nitdriding contributes to better abrasive wear resistance and better galling properties of tested powder metallurgy high speed steel.
Residual Stress Analysis of Steel Fibre Reinforced Composite Inverted-Tooth Chains
Authors: Yavuz Solmaz Murat
Published: December 2013

The aim of this study is to investigate effects on the residual stresses of the fibre orientations and stacking sequences of the inverted-tooth chains which are made of transversely reinforced steel fibre thermoplastic laminated composite materials. For this purpose, fifteen different tooth chain models were created and stress analysis was performed with ANSYS 11.0 finite element program. For each fibre orientation and stacking sequence values of the yield loads where yielding of the inverted-tooth chain just initiates were determined. Then, loads subjected to the inverted-tooth chains were incrementally increased beyond the yield limits to determine plastic and residual stresses that were obtained by removing applied loads from the inverted-tooth chain. As a result of the analysis, it was observed that all values of residual stress components increased depending on the rising applied loads for all fibre orientation as well as for all stacking sequences.
Experimenteller Betriebsfestigkeitsnachweis von Kurbelwellen: Vorstellung eines schädigungsäquivalenten Bauteilprüfkonzeptes
Authors: Rödling Steffen , Fröschl Jürgen , Decker Matthias
Published: December 2013

Kurzfassung

Die Kurbelwelle unterliegt im Betrieb einer komplexen Beanspruchung. Gerade die Übergangsradien der Lagerzapfen zu den Kurbelwangen sowie die Austritte der Ölbohrungen zur Schmierung der Haupt- und Hublagerzapfen stellen schwingbruchgefährdete Stellen dar, welche durch kostenintensive Fertigungs- und Oberflächenverfestigungsprozesse optimiert werden. Um die Untersuchung der Wirksamkeit dieser Maßnahmen in einer Betriebsfestigkeitsprüfung unter möglichst realitätsnaher Beanspruchung zu ermöglichen, wurde bei IABG mbH ein neues Kurbelwellenprüfkonzept entwickelt, welches im folgenden Beitrag vorgestellt und im Vergleich mit gängigen Kurbelwellenprüfverfahren diskutiert wird. Dieses Prüfverfahren ist gleichsam für Kurbelwellen von Reihen- als auch V-Motoren geeignet.
Piezoelectric Driven Testing Facilities to Research the Very High Cycle Fatigue Regime*
Authors: Fischer Christian , Wagener Rainer , Friedmann Andreas , Axt Christoph , Matthias Michael , Melz Tobias , Kaufmann Heinz
Published: December 2013

Cyclic low amplitude loading and a huge number of cycles characterizes the Very High Cycle Fatigue (VHCF) regime. The challenge in research of the Very High Cycle Fatigue regime is to apply this large number of cycles to fracture in an acceptable time frame. For this reason, it is essential to use a machine, which is able to operate at high frequencies of cycles. Two testing machine concepts with piezo actuators are presented in this study. In the first concept, a high performance piezo stack actuator is presented, in which the specimen and the load cell are mechanically assembled in series. This set-up applies forces up to 10 kN and testing frequencies up to 1000 Hz. The second testing facility is a hybrid testing system, which consists of an inertial mass actuator and a servo hydraulic actuator connected in parallel. Both systems are capable of testing normal specimen dimensions and provide the possibility to work with variable as well as constant amplitude loading.
Detection of Corrosion Processes and Fatigue Cracks by Means of Acoustic Emission Monitoring
Authors: Jagenbrein Andreas , Tscheliesnig Peter , Wachsmuth Janne , Bohse Jürgen
Published: December 2013

Kurzfassung

Fatigue crack growth and active corrosion processes are the main causes for structural failures of transport products like road tankers, railway tank cars, and ships. Within the 7th EC framework programme the aim of project CORFAT is to develop a new monitoring technology based on acoustic emission testing (AT) of the structural integrity in terms of proceeding degradation. Differentiation of acoustic emission (AE) signals of real degradation processes by fatigue crack growth or active corrosion from operational or environmental background noise requires the signal classification using also pattern recognition. Therefore, a data base of AE signals related to the different source mechanisms was built up experimentally. In this article selected results of corrosion and fatigue tests in the laboratory as well as results of monitoring background noise during moving of a road tanker are described.
Fatigue Testing of Carbon Fibre-reinforced Polymers under VHCF Loading*
Authors: Gude Maik , Hufenbach Werner , Koch Ilja , Koschichow Roman
Published: December 2013

The rapidly developing market for high strength and high stiffness carbon fibre-reinforced composites demands among others for reliable damage evaluation methods for very high cycle fatigue loading (VHCF). For the analysis of the widely unknown damage behaviour at VHCF loading specific test principles and a shaker based fatigue test stand are developed. Key requirements herein are: high frequency fatigue (f > 150 Hz) without significant warming of the specimen, homogeneous stress distribution and minor through thickness stress gradients as well as adjustable mean stresses for the fatigue testing regarding specific failure modes. Using numerical and experimental investigations a promising solution for the given problem has been found in form of a shear force free bending test stand and a specifically layered specimen.
Microstructure and Microhardness Characterization of Cr3 C2 -SiC Coatings Produced by the Plasma Transferred Arc Method
Authors: Islak Serkan , Eski Özkan , Buytoz Soner , Karagöz Muzaffer , Stokes Joseph
Published: December 2013

The purpose of this work was to investigate the coatings made of Cr3 C2 and SiC powder manufactured on AISI 304 stainless steel applied by the plasma transferred arc (PTA) welding process. SiC content in the produced coated layer was varied between 0–100 wt.% and the effect of SiC concentration on the microstructure and hardness of the coating was measured experimentally. SEM analyses revealed that the composite coatings had a homogeneous, nonporous, and crack-free microstructure. Dendrites and interdendrite eutectics formed on the coating layer, subject to the temperature gradient and the solidification ratio. There was a significant increase in the hardness of coating layers with the effect of the γ -(Fe,Ni), Cr7 C3, Cr23 C6, Fe5 C2, Cr3 Si, CrSi2, Fe>0.64 Ni0.36, CFe15.1, C-(Fe,Cr)-Si phases formed in the microstructure. In comparison to the substrate, the microhardness of the coatings produced by PTA were 2.5–3.5 times harder.