bluuebunny/crossref_metadata_2025 huggingface dataset:
The Study on Fatigue Behavior in Very High Cycle of 5083 Aluminum Alloy
Authors: Yan Gui Ling , Wang Hong , Kang Guo Zheng , Chen Zhou
Published: August 2014

Fatigue tests were carried out at frequent of 20 kHz for 5083 aluminum alloy. The loading way is uniaxial and bending loading. The S-N curve of uniaxial loading presents a duplex curve corresponding to surface fracture and interior fracture. However the S-N curve of the bending fatigue shows the continuous curve. This demonstrates that different loading ways lead to different S-N curve characteristics. For uniaxial loading, almost all crack initiated interior of specimen in the very high cycle regime. The crack source zone appears wear away because of the constant pressure and grinding of this area in the process of cyclic loading. For the symmetric bending loading, the crack of corner in the specimen expands at different rates and direction.
Macro/Meso/Micro Elastic-Viscoplastic Analysis of Plain-Woven Laminates Using Homogenization Theory
Authors: Oide Kohei , Matsuda Tetsuya
Published: August 2014

In this study, macro/meso/micro elastic-viscoplastic analysis of plain-woven laminates is conducted based on a homogenization theory for nonlinear time-dependent composites. For this, a plain-woven laminate is modeled with respect to three scales by considering the laminate as a macrostructure, fiber bundles (yarns) and a matrix in the laminate as a mesostructure, and fibers and a matrix in the yarns as a microstructure. Then, an elastic-viscoplastic constitutive equation of the laminate is derived by dually applying the homogenization theory for nonlinear time-dependent composites to not only the meso/micro but also the macro/meso scales. Using the present method, the elastic-viscoplastic analysis of a plain-woven glass fiber/epoxy laminate subjected to on-and off-axis loading is performed. It is shown that the present method successfully takes into account the effects of viscoplasticity of the epoxy in yarns on the elastic-viscoplastic behavior of the plain-woven GFRP laminate. It is also shown that the results of analysis are in good agreement with experimental data.
Selection of Densification Strain to Predict Dynamic Crushing Stress at High Impact Velocity of ALPORAS Aluminium Foam
Authors: Yahaya Mohd Azman , Ruan Dong , Lu Guo Xing , Dargusch Matthew S. , Yu Tong Xi
Published: August 2014

Cellular material such as aluminium foam has been considered as a potential material for energy absorption upon impact and blast loadings. One of the most important properties that contribute to this feature is the densification strain. At high impact velocity, prediction of the densification strain from quasi-static engineering stress-strain curve has been found inadequate. Furthermore, theoretical prediction using the equation proposed by Reid et al. always over-predicts the dynamic crushing stress. Formation of the shock wave at high impact velocity is believed to further increase the densification level of the foam. However, this effect is disregarded when determining the densification strain quasi-statically. The present study aims to address this issue by determining the densification strain experimentally from impact tests. Forty cylindrical aluminium foams with three different lengths were used as projectiles and were fired towards a rigid load cell by using a gas gun. The peak forces generated from the impact were recorded and analysed. The experimental densification strains were determined physically by measuring the deformation of the foam projectiles after the tests. It is concluded that, at high impact velocity, the densification strain varies with the initial impact velocity. Therefore an appropriate value of densification strain needs to be used in the equation of dynamic crushing stress for a better approximation.
An Analysis of Stainless Steel Micro Square Hole-Flange Using Stretching Processes
Authors: Chen Tsung Chia , Hsu Ching Min
Published: August 2014

This study is focused on the influences of micro stretching process, miniaturized of micro square hole-flange to stainless steel (SUS304) material, and different thicknesses (0.2, 0.1, 0.05mm) of plate. By undergoing finite element program analysis of material parameter corrected by scale factor, we can discover the differences of different thicknesses of plate during micro stretching forming process. The finite element method in this paper is combined with the plastic flow rule of Dynaform and LS-DYNA solver, finite element deformed theory, and updated Lagrangian formulation to simulate the process of micro square hole-flange. The point of this research is by simulating and analyzing all datum of micro stretching forming process, relation between punch load and stroke, distribution of thickness, distribution of stress and strain, the maximum diameter of flange’s hole and the maximum height of flange. Design three pairs of micro square hole-flange tool undergoing micro stretching experience through SUS304 plate. Compare the experience to the results of the simulation to test the reliability of this analyzing program. Through finite element analysis and the results of the experience, we can discover that the minimum of the thickness, the biggest stress and major strain centralize areas where blank and punch corner meet.
Plastic Behavior of Integral Bridge, Consisting of Supporting Steel Beams and Concrete Superstructure, under Spatially Varying Seismic Shock
Authors: Dulinska Joanna M. , Jasinska Dorota
Published: August 2014

The paper presents the dynamic response of an integral bridge to an earthquake registered in Central Europe. The acceleration history of the shock was scaled up to peak ground accelerations predicted for this seismic zone (0.4 g). The seismic action was implemented in the form of two models of three dimensional kinematic excitation: uniform and non-uniform (spatially varying). In the uniform model the assumption was made that the motion of all supports of the bridge was identical. In the case of the spatially varying excitation the wave passage effect was taken into consideration, assuming that the seismic wave propagated along the bridge forcing subsequent supports of the bridge to repeat the same motion with a time delay dependent on the wave velocity. The structural system of the integral bridge consisted of steel girders and crossbars whereas the superstructure was made of a concrete material. To represent the inelastic behavior of the integral bridge during the earthquake, plastic models of both the steel and the concrete material were implemented. For the steel material the classical metal plasticity model with the dynamic failure model of progressive damage, provided by the ABAQUS software, was applied. For the concrete material of the superstructure the concrete damaged plasticity constitutive model was taken into consideration. It turned out that when the non-uniform excitation model was imposed, the tensile damage (cracking) and the degradation of the support zones of the concrete deck were more significant than in case of uniform excitation. The non-uniform excitation model also caused considerably higher inelastic strains of the steel girders and crossbars than the uniform model. This resulted from quasi-static effects caused by ground deformations imposed on the bridge supports during the seismic shock.
Verification of Taylor Impact Test by Using Force Sensing Block
Authors: Iwasaki Fumiaki , Kii Nobuhiko , Iwamoto Takeshi
Published: August 2014

In the Taylor impact test, obtained strain rate becomes in a range of 103~105/s corresponding to penetration of space debris to a space structure. According to this test, a stress value can be calculated by theoretical formulae. However, the formulae include some assumptions and the external force acting on a specimen is not directly measured by using the formulae. In the past study, the split Hopkinson pressure bar (SHPB) is employed instead of a use of a rigid wall which the specimen collides. However, there are two difficulties on this method. The first one is to be a similar range of measurable strain rate to the SHPB technique and the second is to require a sufficiently-large space for a testing apparatus. In contrast, by introducing a force sensing block, the apparatus becomes compact and longer measurable time is realized compared with the SHPB technique. Therefore, the stress value can be measured with higher precision since an extensive range of strain rate can be measurable. In this study, to enhance the precision of the test, it is suggested that the force sensing block is placed just behind the rigid wall for a direct measurement of a time history of external force.
A Numerical Approach for Lower Bound Limit Analysis
Authors: Liu Ying Hua , Xu Bing Ye , Du Xian He
Published: August 2014

In this paper, a numerical procedure for plastic limit analysis of 3-D elastic-perfectly plastic bodies under complex loads is presented. The method is based on the lower-bound limit theorem and von Mises yield criterion so that the lower-bound limit analysis can be conducted by solving a nonlinear mathematical programming problem. A SQP algorithm and a dimension reduction-based technique are used to solve the discretized finite element optimization formulation. A conception of active constraint set is introduced, so that the number of constraints can be reduced greatly. The basis vectors of reduced residual stress spaces are constructed by performing an equilibrium iteration procedure of elasto-plastic finite element analysis. The numerical procedure is applied to carry out the plastic limit analysis of pipelines with part-through slots under internal pressure, bending moment and axial force. The effects of different sizes of part-through slots on the limit loads of pipelines are studied.
Evolution of Recrystallization Textures in Plane-Strain Compressed (001)[110] Aluminum Single Crystals
Authors: Choi Hyun Sik , Han Heung Nam , Lee Dong Nyung
Published: August 2014

The (001)[110] orientation of Al single crystal is known to be metastable with respect to plane strain compression to form the (112)[1 1-1] and (112)[-1-1 1] orientations, known as the copper orientations. The copper orientations did not transform into the cube texture {001}<100> after recrystallization (Rex), at variance with expectation. When Al single crystals were plane-strain compressed and recrystallized (Rexed), their Rex orientation varied with reduction in thickness. These results are discussed based on the strain-energy-release-maximization theory, in which the Rex texture is determined such that the absolute maximum stress direction (AMSD) due to dislocations in deformed materials is parallel to the minimum Young’s modulus direction in Rexed grains and other conditions, whereby strain energy release can be maximized. AMSD is obtained from slip systems activated during deformation and their activities, which were calculated from the VPSC code.
Formability Evaluation Using Modified Cockcroft Criterion with Strain Paths for Sheet Metal Forming
Authors: Lee Rong Shean , Chien Ta Wei
Published: August 2014

In most situations, original Cockcroft criterion underestimates material formability in the first quadrant of FLD. So far, some modified Cockcroft criteria have been reported for different applications. This presentation will focus on the modified Cockcroft criterion which takes strain-path effect into consideration. This paper demonstrates the accuracy of this criterion through limiting dome height test, free bulge test, and the biaxial tensile test using cruciform specimen respectively. The results showed that the modified Cockcroft criterion with strain path effect has good agreement with experimental results.
Tube Hydroforming of Fuel Filler Pipes with Movable Dies
Authors: Hwang Yeong-Maw , Hsieh Shin Yan , Chen Ming Chung
Published: August 2014

Tube hydroforming is a relatively new approach to manufacture light weight metal structures. As the manufacturing technology became advanced, demands of lighter and stronger metal structures are also increasing. This research is to use tube hydroforming to expand the tube of a fuel filler for cars. The pipe material is JIS G3141. The product has a large expansion ratio at the edge of the pipe. Traditional tube hydroforming is difficult to achieve this large expansion ratio of a metal product. Tube hydroforming with movable dies is proposed to enhance the capacity of tube hydroforming technology. With movable die design, product with more uniform thickness can be obtained, and the forming pressure becomes lower than that needed in tube hydroforming without movable dies. A finite element code DEFORM-3D is used to analyze the plastic flow pattern of the tube. The loading paths of internal pressure, axial punches and movable dies for obtaining a sound product are determined by an adaptive simulation algorithm. The thickness distributions of the product for different loading paths are discussed.
Study of Microhardness and Young's Modulus of Copper Thin Film by Tip-Grit AFM Scratch Technology in Various Environments
Authors: Chen Chao Chang Arthur , Chao Chun Chieh , Huang Kuo Wei , Fu Wei En
Published: August 2014

This paper is devoted to investigate an estimation methodology of micro hardness and Young’s modulus of reacted passivation layer of deposited copper thin film in dry and wet environment based a tip-grit atomic force microscope (TGAFM) scratch on copper thin film of silicon wafer. The TGAFM is a modification or attachment of a nanoor micron grit on the tip apex or cantilever beam of a closed-loop control AFM instrument. In this study, a diameter 800 nm SiO2 grit glued on the apex of the tip of AFM is used for experiment. Tip force model has been developed based on Hertzian model and Tresca criterion for stress-strain relationship from the geometries of scratch groove, depth and width to evaluate about microhardness and Young's modulus of copper thin film in regular air and DI-water. Experimental results show that the microhardness (H) is 1.62GPa and the Young's modulus (E) is 160.52GPa of copper thin film in DI-water environment. These mechanical properties of copper thin film is larger than the H= 1.52GPa and E= 126.04GPa for dry environment. Results of this study can be further explored to the grit force reaction on the passivation layer of copper film of chemical mechanical planarization (CMP) process development for semiconductor industry.
Experimental Study on Forging Process of Micro Stepped Gear
Authors: Chen Chang Cheng , Qiu Yi Xuan
Published: August 2014

This paper proposes an integrated computer-aided design and computer-aided manufacturing procedure to produce the forging die for experiment, and the forging formability of micro stepped gear was explored. In the forging process, this paper proposes a novel hybrid forging method with a single die set which would execute two forging stages including the first stage of Upsetting and the second stage of Clamping type Gear forging. In the case study, the materials were fully filled into tooth cavity of small gear of module 0.12mm. On the other hand, the estimated unfilled rate of bigger gear is less 8 to 12%, showing this method is exactly feasible.
Bauschinger Effect Exhibited in Advanced High Strength Steel Sheets under Cyclic Tension and Compression Tests
Authors: Tsai Heng Kuang , Chen Fuh Kuo , Wang Shi Wei
Published: August 2014

The Bauschinger effect exhibited in the advanced high strength steel sheets was examined by conducting cyclic tension-compression tests. The experimental device for performing the cyclic tension and compression tests with a single sheet specimen was developed in the present study. The experimental apparatus consists of a novel constraint jig that could prevent the sheet specimen from buckling during the compression test. The efficiency of the developed clamping device was validated by both the finite element analysis and the cyclic tension and compression tests conducted in the present study. The test results reveal that the advanced high strength steel exhibits significant Bauschinger effect. It is also confirmed that the finite element prediction of springback present in the stamping of advanced high strength steel sheets is more consistent with the experimental results if the Bauschinger effect is considered.
On the Relation between R-Value of a Grain and the Operating Slip Systems of the Grain
Authors: Abe Takeji
Published: August 2014

The r-value is defined as the ratio of the width strain to the thickness strain under uniaxial tensile loading. The r-value can be defined for each grain in polycrystalline metal during plastic deformation. It was pointed out that r-value of a grain affects the surface roughening of polycrystalline metal, and hence also affects the formability of thin sheet metal. On the other hand, it was shown that by using a rate-type constitutive relation for crystal slips the effect of the number of active slip systems on the yield curves is clarified. In the present paper, the relation between r-value of a grain and its operating slip systems in polycrystalline metals is studied.
Energy Absorption Capacity of Expanding Tube with Fiber-Reinforcement
Authors: Chai Gin Boay , Lu Guo Xing
Published: August 2014

Abstract. This contribution presents the investigation of energy absorption mechanism of metal tubes and composite-wrapped metal tubes subjected to a diametric deformation via an expansion process. In the experiments, the expansion of the tubes was performed under quasi-static loading using a conical-cylindrical expansion die. The experimental results are repeatable and thus reliable. An extensive finite element analyses and experimental investigation were carried out in parallel. Both two-dimensional and three-dimensional finite element models were created based on the actual experimental geometrical and material parameters. Results from the finite element analyses correlate rather well with the experimental data. Glass fibre-wrapped metal tubes showed an increased steady-state reaction force which in turn reflects better specific energy absorption capacity for every layer of composite wrapped as compared to bare metal tubes.
Elastic-Plastic Fracture Mechanics Analyses of Surface Cracks in Drill String Subjected to Combined Loading
Authors: Zhao Guang Hui , Wang Hao Han , Shi Jian , Zhao Li
Published: August 2014

The drill pipe near the surface stands the largest tension and torsion load for the full hole during drilling operation. And fatigue crack growth is always the major cause of failure of drill string. As an example, 5ʺ drill pipe that was near the well head of an ultra-deep straight well and made of 30CrMo, whose constitutional relation was fitted by experiment, was analyzed here. Simplifying the initial crack of the drill pipe as circumferential semi-elliptical surface crack, we simulated the elastic-plastic fracture feature of the drill string with surface crack, partly through-wall crack and fully through-wall crack under combined loading of axial force and torsion. Crack front geometry evolvement is simulated for the different stages of crack propagation. This work would provide a basis for the full-range analysis of fatigue crack growth.
Multi-Phase-Field Analysis of Stress–Strain Curve and Ferrite Grain Formation during Dynamic Strain-Induced Ferrite Transformation
Authors: Yamanaka Akinori , Takaki Tomohiro
Published: August 2014

A numerical model of dynamic strain-induced ferrite transformation (DSFT) was developed by combining the multi-phase field model with the Kocks–Mecking model. Using the developed model, a three-dimensional simulation of the DSFT in a Fe-C alloy was performed to study the correlation between the variation in flow stress and the microstructure evolution during the DSFT. The simulation results indicated that the developed model successfully simulated the characteristic DSFT behavior, i.e., both the stress–strain curve with a single peak and the formation of an ultrafine-grained ferrite microstructure. The variation in the flow stress during the DSFT was characterized by the volume fraction of the ferrite phase.
The Effect of Mo and Al on the Corrosion Behavior of Titanium and Some of its Alloys for Biomedical Applications
Authors: Mirza Rosca Julia , Baltes Liana Sanda , Tierean Mircea Horia
Published: August 2014

The influence of molybdenum and aluminum on the corrosion resistance of the Ti and other Ti-based biomedical implant alloys under simulated physiological conditions is presented. Ti and its alloys Ti-10Mo and Ti-10Mo-10Al were studied. The electrochemical impedance spectroscopy technique was used and the experimental results were compared with those obtained by potentiostatic and potentiodynamic techniques. All the measurements were made in Ringer ́s solution at different pH and at different potentials as Ecorr, -650, -500, 0, +200 and +400 mV vs SCE. It was evident that Mo improved passivity and limited the active corrosion of the β-phase of Ti while Al enrichment of the α-phase was found to be detrimental to the passivity and corrosion resistance of Ti. In most experimental conditions, the passive film is formed by TiO2, Ti2O3and TiO. When pH is very low, thermodynamically stable state of Ti is titanium anion Ti3+.
Damage Detection in Flux Cored Wire Welded Structures by Using Vibration Testing
Authors: Tocarciuc Alexandru , Bereteu Liviu , Drăgănescu Gheorghe
Published: August 2014

In welded structures subjected to dynamic cyclic loads may appear and propagate fatigue cracks due to local structural damage. These cracks may initiate due to technological damages induced by welding process, or by environmental operating conditions. In the present work, it is determined, by the means of Finite Element Method (FEM), the natural frequencies and mode shapes of more steel specimens that are welded together. The analysis is carried out in undamaged condition as well as in damaged one, after the damage has been artificially induced. The experimental measurement of the vibration response is carried out by using a condenser semi-professional microphone Samson C01U, which is suitable for high-fidelity acoustic measurements in the frequency range of 40 18.000 Hz. A first post-processing of the vibration responses of the welded specimens, in free-free conditions, is carried out using an algorithm based on Prony series. A second post-processing is carried out by means of signal processing using DWT together with Shannon entropy. The results are compared to modal parameters estimated using FE Analysis.
Experimental and Numerical Investigations of TBC Behaviour after Aging, Subjected to Tension and Bending
Authors: Sadowski Tomasz , Golewski Przemysław
Published: August 2014

Thermal Barrier Coatings (TBCs) have been extensively used in aircraft engines to improve durability and performance. They protect critical engine parts such as blades and combustion chambers, which are exposed to high temperatures and corrosive environment.Testing of coated metallic alloys, subjected to ageing process, allows determination of the TBCs properties. In this paper we performed 2 tests: uniaxial tension and bending. The aging of samples was carried out in 1000°C for times: 48h, 89h, 185h and 353h. Thermally Grown Oxide (TGO) layer thickness (SEM observations) and the strain level corresponding to damage of the TBCs were determined experimentally.The experimental results were used to build numerical model in Abaqus program. Brittle cracking damage model was applied to describe of the TBC layer degradation. Surface based cohesive behavior was used to model delamination of the interface between a bond coat (BC) and a top coat (TC).The proposed numerical model describes with high accuracy experimental results.
Determination of Mechanical Properties of Chondrocytes in Articular Cartilage Using Atomic Force Microscopy
Authors: Florea Cristina , Jakorinne Asmo , Lammi Mikko , Davidescu Arjana , Korhonen Rami Kristian
Published: August 2014

Atomic Force Microscopy (AFM) based nanoindentation is a widely used technique for measuring mechanical properties of living cells, providing information for understanding their mechanobiological behavior. However, very local properties of cell surfaces have not been characterized earlier. The goal of this study was to develop an AFM-based technique to determine local elastic properties of bovine articular chondrocytes. The Youngs modulus of chondrocytes was 19.3 ± 5.6 kPa for spread cells and 10 ± 4.1 kPa for the round cells. The results were compared to previous studies in which different techniques were used to obtain more global properties of chondrocytes. Our findings suggest that using nanosized AFM tips, the very local cell properties can be measured.
Heat Transfer in Composites Subjected to Temperature Variations
Authors: Sadowski Tomasz , Golewski Przemysław
Published: August 2014

The heat transfer problem in the 2-phase composite material containing metallic and elastic phases, subjected to quick temperature variations, is the aim of theoretical analysis. The full description of the composite behaviour starts from the formulation of governing equations at 2-scale levels: micro-and macro-, passes through specification of the internal structure of the composite and finishes by numerical solution of the heat transfer problem through the considered material sample. The most important in the analysis are thermo-mechanical properties of the composite components creating the material. The big difference of the both phases properties (mismatch) can create additional difficulty in the exact thermal description of the composite. It is necessary also to specify by scanning electron microscopy (SEM) observations a real material internal structure, which includes: grain shapes and matrix, to create of the proper size of the Representative Volume Element (RVE) for numerical calculations.In the numerical example we analyse cermet, i.e. the composite build up of metallic matrix (cobalt) and tungsten carbide elastic grains, which exhibits high brittleness. Heat transfer across this very complex material causes heat flux concentrations in the metallic phase and further stress concentrations. These concentrations act as sources of damage initiators at the binder/carbide grains interfaces. The obtained results lead to the conclusion that the spatial distribution and content of the metallic phase first of all influence the heat transfer across the 2-phase composites.
Structural Characteristics of Ductile Iron at Different Rare Earth Contribution from a Magnesium Ferrosilicon Alloy
Authors: Uta Valentin , Riposan Iulian
Published: August 2014

The structural characteristics of ductile irons were studied using different rare earth elements (REE) in Mg-FeSi treatment alloys (0.005 - 0.025%REEres), in un-inoculated and Ca-bearing FeSi in the mould inoculated irons. In relatively high purity base iron, in terms of anti-nodularising trace elements, (Thielman factor K = 0.7-0.8), increasing REE content after Mg-treatment aggravated the carbides tendency and decreased the nodular graphite compactness, in both un-inoculated and inoculated irons. Graphite parameters improve for lower REE content, and, in both cases, for inoculated irons. A low content of REEres (0.005 to 0.01%) for K < 0.8 is practical and sufficient in a Ca-bearing FeSi alloys inoculated iron to control carbides sensitivity and to sustain acceptable nodular graphite morphology formation.
Sample Preparation and HR-TEM Investigation Techniques of Ti Based, Ga Containing, Amorphous Alloys
Authors: Locovei Cosmin , Nicoară Mircea , Răduță Aurel
Published: August 2014

Titanium based bulk metallic glasses (BMGs) are characterized by properties such as high corrosion resistance, Youngs modulus, hardness, fracture strength and wear resistance that recommend them as performant biomaterials for orthopedics and dentistry. Present researches have been focused on some Ti-Zr-Cu-Ga-Si-Sn alloy which could be feasible alternative to almost classical nickel containing BMGs. has been casted by vacuum suction in a copper mold. Suction casting has been used to produce by mean of ultra-rapid cooling experimental samples as 2mm cylinders, and complex investigation program based on optical microscopy, SEM, and HR-TEM techniques has been performed to characterize resulting microstructure. Although presence of gallium produces considerable difficulties in sample preparation, investigations based on high resolution transmission electron microscopy (HR-TEM) have evidenced simultaneous presence of amorphous, crystalline and partially crystalline structures.
Stainless Steel Brackets: In Vitro Corrosion Behaviour and Mechanical Debonding Test
Authors: Cotrut Mihai Cosmin , Tarcolea Mihai , Vrânceanu Maria Diana , Gherghilescu Ana Iulia , Ghiban Nicolae , Baciu Florin , Ionescu Ionut Cornel
Published: August 2014

The purpose of the study was to investigate the microchemical, morphological, mechanical and anticorrosive characteristics of the metallic brackets by using energy-dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), electrochemical and shear tests. The changes resulted from the exposure of the metallic brackets to artificial saliva and debonding forces were investigated under orthodontic appliances. The results have shown that metallic brackets studied in this paper present a good design, great electrochemical behaviour in artificial saliva for different pH values (2, 5 and 7), and also great mechanical properties. In the case of shear stress the obtained values were higher than the clinical accepted value. The metallic brackets studied in this paper present a good behaviour in artificial saliva, and good mechanical characteristics. The ARI investigation revealed that most of the adhesive was left on the bracket.
Study of Superelastic Behavior of CuAlBe Shape Memory Alloy by Neutron Diffraction
Authors: Dubois Matthieu , Brown Don , Clausen Bjørn , Addad Ahmed , Lodini Alain
Published: August 2014

The aim of this work is to understand the evolutions of the β1metastable austenite phase of a CuAlBe Shape Memory Alloy at macroscopic and microscopic scales under mechanical solicitation by neutron diffraction. The tensile specimen, taken in the raw material is subjected to superelastic cycles at room temperature on SMARTS diffractometer. Before loading, the mater ial is fully austenitic. During loading, after elastic deformation of austenite, phase transformation starts, martensite variants appear. The material follows a law of pseudo elastic behavior. At the end of the first mechanical cycle after unloading, the macroscopic curve does not fully return into its original point. A macroscopic deformation is observed. The evolution of first order microdeformations during mechanical cycles shows a large deformation of {400} plane family. This deformation is linked to the presence of <001> partial fibber characterizing the crystallographic texture of the material after elaboration. The FWHM of the (400) diffraction peak is also largely increased during loading. This increase is the signature of the generation of stacking faults during the transformation of β1metastable austenite into β1martensite.
Nodular Inhomogeneous Graphitization – Determining Factor of Fatigue Failure
Authors: Lițǎ Marin , Opriș Carmen
Published: August 2014

The paper investigates the causes that led to the premature failure of a crankshaft (approximately 200 hours) from an engine used in equipment that worked on a construction site for concrete pumping. Microscopic analysis (optic and electronic), chemical and macroscopic investigations were conducted in order to find the causes of breakage of the crankshaft.
The Effect of Laser Shock Processing on Corrosion Resistance of Stainless Steel AISI 316L
Authors: Roman Ionut Bogdan , Tierean Mircea Horia , Baltes Liana Sanda , Mirza Rosca Julia
Published: August 2014

The paper presents the effect of laser shock processing on stainless steel 316L corrosion resistance. The samples were laser welded and mechanical treated using a Nd:YAG laser with a 1064 nm wavelength, and two different pulse density: 900 pulse/cm2 and 1600 pulse/cm2. After the laser shock processing, the samples were subjected to a seawater solution for corrosion testing. The curves obtained were statistically modeled using Stern-Geary equation. One may observe that the corrosion speed of the LSP samples treated with 900 pulse/cm2 is eight times higher than the corrosion speed of the LSP samples treated with 1600 pulse/cm2.
Wear Behaviour of New CoCrMoTi Dental Alloys
Authors: Ghiban Nicolae , Ghiban Alexandru , Ghiban Brânduşa , Borţun Cristina Maria
Published: August 2014

A new composition of a dental cobalt alloy was proposed from the system CoCrMoTi, which are proposed for dental applications. Three content of titanium were used in commercial matrix of CoCrMo alloy in order to reveal the wear behavior of these alloys. The results showed that titanium alloying may improve wear behaviour by increasing the friction coefficient.
Metallic Biomaterials Processing Technologies in Order to Obtain a New Design for a Hip Prosthesis Femoral Component
Authors: Niculescu Marius , Antoniac Iulian Vasile , Blajan Ana
Published: August 2014

The paper presents the processing technology that could be used in order to obtain a new design of a stem component for a hip prosthesis type lattice beam. This new design was made based on the analysis of the currently successful stems used in clinical practice and on different biomechanical and biomaterials criteria. Metallic biomaterials used for manufacturing different components for hip prosthesis are usually austenitic stainless steel type 316L, Co-Cr alloy and titanium based alloy. In our study, considering the specific design of the stem, stainless steel type 316L with the nominal compositions (%weight): C <0.03, Cr 17, Ni 14.5, Mo 2.7, Mn <2.0, Si <1.0, P <0.025, S <0.010, Fe balance is used. Different mechanical processing techniques were used in order to obtain the experimental prototype. According to the well-known limitation of the stainless steel type 316L as biomaterial for long term implants, we propose for the new stem component to use a TiN coating obtained using magnetron sputtering technique. The cytotoxicity studies were performed using a CCl 81 (VERO) stabilized cellular line, in order to analyse the biocompatibility properties. The samples were examined for the development of the cellular culture, in order to compare the results obtained using direct contact method. From the point of view of these tests, it was not observed an essential modification of cells and the cellular morphology is not affected by the presence of the TiN coated metallic samples. In the conclusion, the new geometry proposed for a stem component of cemented hip prosthesis could be made using different mechanical processing techniques and appears to be a potential solution in order to solve the problems related to the stability of the total hip prosthesis, with improved biocompatibility properties due to the TiN coatings.
Nanocrystalline/Nanosized Mixed Nickel-Manganese Ferrites Obtained by Mechanical Milling
Authors: Chicinaş Ionel , Marinca Traian Florin , Neamţu Bogdan Viorel , Popa Florin , Isnard Olivier
Published: August 2014

A sum of mixed nickel-manganese ferrites, NixMn1-xFe2O4(x=0, 0.3, 0.5, 0.7) were synthesized by classical ceramic route starting from stoichiometric mixtures of commercially MnO2, NiO and Fe2O3. The polycrystalline ferrites obtained by ceramic route were subjected to the mechanical milling procedure in order to reduce the particles size and to refine de crystallites size. A planetary high energy ball mill Fritch Pulverisette 4 was used and the milling time was up to 120 minutes. The ceramic and as-milled ferrites samples were investigated by X-ray diffraction (XRD), scanning electronic microscopy (SEM) and laser particles size analysis (LPSA). After 15 minutes of milling the mean crystallites size for each one of the nickel-manganese ferrites is in nanometric range. After 120 minutes of mechanical milling for all ferrites types the mean crystallites size is at 6-8 nm, depending on Ni/Mn ratio. According to the SEM and LPSA investigations the milled ferrites powders consists in nanometric particles alongside of the micrometric ones. The micrometric particles are formed by multiple nanocrystallites.
Optimizing the Parameters of Reactive Sintering for In Situ Fabrication of Al-Al2O3 Composites
Authors: Nicoara Mircea , Raduta Aurel , Locovei Cosmin , Opriș Carmen , Sosdean Danut , Vasiu Radu , Gnadt Francisc , Lungu Daian
Published: August 2014

Fabrication of aluminum-based composites reinforced by ceramic particles or intermetallic phases has focused considerable attention in recent decades because significant improvement in mechanical properties and thermal stability. This paper has considered in-situ fabrication by mean of reactive sintering of blended and compacted powders containing an aluminum-copper hardenable alloy and titanium dioxide. An experimental program has been dedicated to optimize the sintering parameters in terms of both treatments temperature, between 650 and 800°C, and duration, in the range of 3 to 6 hours. Microstructural analysis based on Scanning Electron Microscopy (SEM) has been used to determine of distribution of elements involved in sintering reactions, such as aluminum, titanium and oxygen.
Properties and Microstructure of HVOF Thermally Sprayed Carbide Based Coatings
Authors: Hulka Iosif , Uţu Ion Dragoş , Şerban Viorel Aurel , Vuoristo Petri , Niemi Kari , Koivuluoto Heli
Published: August 2014

The current study is focused on deposition of different carbide based powders as WC/10Co/4Cr, Cr3C2/25NiCr, CrC/37WC/18M using High Velocity Oxygen Fuel (HVOF) spraying technique onto the surface of low carbon steel substrates. The obtained coatings were characterized by means of X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) to study their phases and morphology. Hardness and porosity values of the coatings were also measured. The sliding wear behavior was evaluated using the pin-on-disk method and the corrosion resistance was determined by open cell potential measurements and salt spray tests. Comparative results of the investigated samples showed that the WC/10Co/4Cr coating had the best wear properties and the Cr3C2/25NiCr coating had the best corrosion resistance.
Composite Powder and Compacts of Iron/Iron Oxide Type Produced by Mechanosynthesis and Reactive Sintering
Authors: Marinca Traian Florin , Neamţu Bogdan V. , Popa Florin , Chicinaş Ionel , Isnard Olivier
Published: August 2014

Composite powder of Fe/Fe2O3type was synthesized by mechanical milling using commercially Fe and Fe2O3powders in mass ratio of 35/65. The milling process leads to the powder homogenization, powder activation and formation of some Fe/Fe2O3composite particles. The Fe/Fe2O3composite powder obtained by mechanical milling and the un-milled Fe/Fe2O3mixture were subjected to the reactive sintering procedure in argon atmosphere at 1100 °C for 6 hours. The sintering procedure promotes the reaction of the Fe with the Fe2O3and the result is a sintered composite compact of Fe/Fe3O4/FeO type. The microstructure of the Fe/Fe3O4/FeO sintered composite compacts presents iron clusters in an oxide matrix. A more homogeneous iron clusters size and distribution in oxide matrix is observed in the case of the sintered compact obtained from mechano-activated powder. The X-ray diffraction (XRD), laser particles size analysis (LPSA), optical (OM) and scanning electron (SEM) microscopies techniques were used for the investigations.
Experimental Research on Modern Methods of Welding Pipelines Using Base Materials X60 and X70
Authors: Hanea Camelia Maria , Iovanas Radu , Roată Ionut Claudiu , Pascu Alexandru
Published: August 2014

The aim of the research is to highlight the properties of the welded joints of the steels that are used for mains X60 and X70. X60 and X70 steels were welded by automatic welding procedure (STT) at the root and also by automatic MIG procedure for the filling layers. Thereby an increase between 6 15 [%] of the weld bead hardness was obtained in the case of the X 60 steel welding. An increase of bead fracture strength was also noticed from 570 [N/mm2] X 60 steel to 646 [N/mm2] X70 steel.
About Replacement of Nickel as Amorphization Element for Fabrication of Ultra-Rapidly Solidified Ti-Zr Alloys
Authors: Raduta Aurel , Nicoara Mircea , Locovei Cosmin , Stoica Mihai , Eckert Jurgen
Published: August 2014

Amorphous alloys based on titaniumzirconium seem to be perfect candidates as metallic biomaterials. However, the most successful results are based on alloying elements such as nickel, which is responsible for allergic effects to a considerable percent of human population. Therefore the elimination of nickel and addition of other alloying elements with amorphization effect, such as gallium and/or hafnium, have been considered for this paper. Starting from already classic Ti-Zr-Cu-Ni-Si-Sn composition, samples with additions of gallium and hafnium at the expense of nickel have been fabricated by mean of ultra-rapid cooling, using copper mold suction casting. The structures of the as-cast rods have been investigated using X-rays diffraction and electron microscopy.
An Axiomatic Design View on Part Orientation Schemes
Authors: Banciu Felicia Veronica , Drăghici George , Pămîntaş Eugen
Published: August 2014

the paper proposes an axiomatic design view of orientation schemes used in fixture design, in context of using the axiomatic design rules and guidance to fixture design. In this paper the axiomatic design, matrix and rules are applied to orientation schemes in order to see what kind of designs result (uncoupled, decoupled) and how can be applied the information axiom to choose among the orientation schemes that one (s) that are best suited for the declared purposes-minimum orientation errors.
Integration of CAD CAM Techniques in the Development of an Injection Mould for Automotive Parts
Authors: Adam Andrei , Cosma Cristian , Dume Adrian Ilie , Jadaneantu Sorin
Published: August 2014

Processing by injection is the technological process by that the thermoplastics material is injected, under pressure, in the cavity of a mould, where it cools down and solidifies. This process is the most common method for obtaining plastic materials. Injection moulding of thermoplastics has emerged as the premier vehicle for delivering high quality, value added commercial products. Continued global competitiveness has increased standards for product capability and quality while requiring reduced product development time and unit cost. Despite advanced design methods and new process technologies, it is becoming apparent that the injection moulding process is neither flexible nor robust. This paper presents a design process using CAD-CAM software applied to an injection mould for manufacturing a plastic component that is used in the automotive industry. The component was analyzed, measured and subjected to simulations that will certify the quality of the final product.
Mechanical Behavior of Fe60Co14Ga2P10B5Si3Al3C3 Bulk Metallic Glass
Authors: Buzdugan Dragoş , Codrean Cosmin , Şerban Viorel Aurel , Vodǎ Mircea
Published: August 2014

Development of Fe-based bulk metallic glasses (BMG) with good mechanical and soft magnetic properties has become a major objective in the materials science field. Bulk metallic glasses present an interesting combination of properties. They exhibit very high strength (both in tension and compression), large elastic elongation limit, high hardness, excellent corrosion resistance, and good soft magnetic properties. These properties makes them suitable for many applications like high resistant control cables, pressure vessels, micro-components, pressure sensors, microgears for motors, magnetic cores for power supplies and hard fibers in composite materials. Multi-component Fe60Co14Ga2P10B5Si3Al3C3bulk metallic glass was synthesized in rod form with a diameter of 1 mm by copper mould casting technique using raw industrial materials. The obtained alloy was analyzed by X-ray diffraction (XRD), differential thermal analysis (DTA) and scanning electron microscopy (SEM) techniques, in order to determine the phase constituent, the thermal stability and the fracture surfaces of as-cast samples. The mechanical behaviour was investigated by microhardness and compression tests. The values recorded for hardness and fracture strength includes this alloy in the category of high resistant materials.
The Influence of Sulphur and Oxigen Additions in Mg-Treated Iron on the Cooling Curves Parameters
Authors: Anca Denisa Elena , Panciu Elena , Chisamera Mihai
Published: August 2014

The main objectiv of this experimental reserch is a comparative analysis of sulphur and oxygen effects on the cooling curves parameters at different iron melt modifying potential (residual Mg content). For the experiment, three irons with different modifying potential (0.0014, 0.0213 and 0.033 wt % residual Mg content respectively) were developed. After Ca-Ba inoculation, the three irons were additional treated by stoichiometric equivalent additions of sulphur or oxygen as FeS2 and Fe2O3 respectively. Both FeS2 and Fe2O3 sources were placed on the bottom of standard Quik-Cup moulds,usualy used for iron melt thermal analysis. The effect of sulphur and oxygen on the standard and nonconventional cooling curves parameters were evaluated to a more deep understanding of the cast iron solidification mechanism. The cooling curves parameters are strongly influenced both by the initial residual Mg level of iron melt and afterwords sulphur/oxygen additions. A very complex and sometimes confused variation of the cooling curves parameters was recorded because of different actions of the three factors (iron melt modifying potential, sulphur and oxygen). As a previous paper highlighted, sulphur addition has a strong graphite decompactizing effect while oxygen addition has mostly an inoculant effect.
Joint Quality Assessment of Three Different Laser Welded Dental Alloys
Authors: Ardelean Lavinia , Reclaru Lucien , Bortun Cristina , Rusu Laura Cristina
Published: August 2014

The aim of this study is to assess the quality of laser welded joints, by different methods such as: scanning electronic microscopy, metallography, microhardness testing, spectrographic and radiographic analyses. The alloys assessed are a titanium-based alloy used in manufacturing prefabricated pieces for implantology, a standard AuPd alloy for the metallo-ceramic technique and a Cr-Co-Mo alloy used for manufacturing the metallic components of partial dentures. The conclusion of the testing is that laser welded joints are generally mechanically satisfactory. Laser is best suitable to weld titanium and its alloys because they have higher rates of laser beam absorption and lower thermal conductivity than other dental casting alloys.
Description of Degradation Process of Rubberized Lean Concrete
Authors: Sadowski Tomasz , Pietras Daniel
Published: August 2014

Waste tires create big problem in the world as for their utilization. One domain in which this material is able to found promising application is civil engineering. The waste tires additive in the concrete manufacturing leads to change of mechanical properties such as: Young modulus, compressive strength, fracture toughness, energy absorption, brittleness, water absorption etc. It was partly reported in the literature only for the plain concrete. There is no investigations for a lean concrete - the material which has potential applications as a subgrade of roads.
The aim of this paper is to investigate the importance of the rubber particles addition in the lean concrete production as for modification of the basic mechanical properties and further degradation of the material due to mechanical loading. The new technology of compaction of the concrete was elaborated to perform basic test: cyclic uniaxial compression and cyclic bending. In order to describe gradual degradation of the rubberized lean concrete a scalar damage parameter D related to loading history was proposed. The current value of the elastic modulus was expressed as E=Eo(1-D), where Eo denotes the initial value of the Young’s modulus.
The paper includes also a numerical model of the beam made of the rubberized lean concrete, which is subjected to 3-point bending deformation. The stress distribution in this beam is highly non-homogeneous with visible stress concentrations around the rubber particles.