bluuebunny/crossref_metadata_2025 huggingface dataset:
Onset of calving at supraglacial lakes on debris-covered glaciers of the Nepal Himalaya
Authors: Sakai A. , Nishimura K. , Kadota T. , Takeuchi N.
Published: December 2009

Field surveys of supraglacial ponds on debris-covered glaciers in the Nepal Himalaya clarify that ice-cliff calving occurs when the fetch exceeds ∼80 m. Thermal undercutting is important for calving processes in glacial lakes, and subaqueous ice melt rates during the melt and freeze seasons are therefore estimated under simple geomorphologic conditions. In particular, we focus on the differences between valley wind-driven water currents in various fetches during the melt season. Our results demonstrate that the subaqueous ice melt rate exceeds the ice-cliff melt rate when the fetch is >20 m and water temperature is 2–4°C. Calculations suggest the onset of calving due to thermal undercutting is controlled by water currents driven by winds at the surface of the lake, which develop with expanding water surface.
A subglacial water-flow model for West Antarctica
Authors: Le Brocq A.M. , Payne A.J. , Siegert M.J. , Alley R.B.
Published: December 2009

The current generation of continental-scale ice-sheet models cannot successfully reproduce the complex ice/water/sediment interactions of the West Antarctic ice sheet (WAIS) in a physically meaningful manner. The potential of a thin-film-based subglacial water-flow model for incorporation into a continental-scale coupled ice/water flow model of the WAIS is evaluated in this paper. The subglacial water-flow model is applied to the Ross Sea sector of the WAIS, in both a steady-state and time-dependent form, to derive the equilibrium water depth for the present-day configuration. The potential for coupling the model to an ice-flow model is then demonstrated, using a variable sliding parameter that is a function of the subglacial water depth. A coupled ice/water flow model, using the parameterization tested in this paper, could have the potential for reproducing the surface elevation, velocity and thermal regime of the WAIS successfully. These requirements are crucial in modelling the evolution of the WAIS, and must be addressed before reliable continental-scale predictive models can be utilized.
Stability algorithm for snow micro-penetrometer measurements
Authors: Bellaire Sascha , Pielmeier Christine , Schneebeli Martin , Schweizer Jürg
Published: December 2009

Information on snow-cover stability is important for predicting avalanche danger. Traditionally, stability evaluation is based on manual observations of snow stratigraphy and stability tests, which are time-consuming. The SnowMicroPen (SMP) is a high-resolution, constant-speed penetrometer to measure penetration resistance. We have analysed the resistance signal to derive snow stability. The proposed stability algorithm was developed by comparing 68 SMP force–distance profiles with the corresponding manual profiles, including stability tests. The algorithm identifies a set of four potentially weak layers by taking into account changes in structure and rupture strength of microstructural elements that make up snow layers as derived from the SMP signal. In 90% of the cases, one of the four potentially weak layers proposed by the algorithm coincided with the failure layer observed in the stability test. To select the critical layer from the four potential weaknesses was more difficult. With fully automatic picking of the critical layer, agreement with the failure layer observed in the stability test was reached in 60% of the cases. To derive a stability classification, we analysed weak-layer as well as slab properties. These predictor variables allow the SMP signal to be classified into two stability classes, poor and fair-to-good, with an accuracy of ∼75% when compared with observed stability. The SMP, in combination with the proposed algorithm, shows high potential for providing snow-cover stability information at high resolution in time and space.
Bertold Löffler's Bookplate for Sigmund Freud
Authors: Pichler Gerd
Published: December 2009

Around 1901, the Viennese graphic artist Bertold Löffler created a bookplate for Sigmund Freud. The history of this bookplate's creation was hitherto unclear. The present article explores the circumstances of the bookplate's creation and the context of this interesting connection between the well-established scientist and the young, unknown artist: the contact was negotiated by Löffler's colleague, Carl Maria Schwerdtner, whose brother Hugo was a student of Freud and commissioned the bookplate as a gift from Freud's students.
Freud's ‘The “Uncanny”’ and Deconstructive Criticism: Intellectual Uncertainty and Delicacy of Perception
Authors: Bartnæs Morten
Published: December 2009

Freud's ‘The “Uncanny”’ (1919) has been the object of a singular growth of interest, though mainly outside the realm of psychoanalysis. The article owes its present prominence in the humanities to its reception and appropriation by readers associated with deconstruction, starting with Jacques Derrida, and continuing with the influential interpretations of Hélène Cixous (1972), Samuel Weber (1973) and Neil Hertz (1985). The present article discusses some characteristics of the deconstructive reception of ‘The “Uncanny”’, and points out the limitations it puts on the understanding of Freud's text.
The Berlin Tradition in Chicago: Franz Alexander and the Chicago Institute for Psychoanalysis
Authors: Schmidt Erika S.
Published: December 2009

Freud considered Franz Alexander, the first graduate of the Berlin Psychoanalytic Institute and an assistant in the Berlin Polyclinic, to be ‘one of our strongest hopes for the future’. Alexander went on to become the first director of the Chicago Institute for Psychoanalysis in 1932 and modeled some of the Chicago Institute's mission on his Berlin experiences. He was also a researcher in psychosomatic medicine, a prolific writer about psychoanalysis and prominent in psychoanalytic organizations. As he proposed modifications in psychoanalytic technique, he became a controversial figure, especially in the elaboration of his ideas about brief therapy and the corrective emotional experience. This paper puts Alexander's achievements in historical context, draws connections between the Berlin and Chicago Institutes and suggests that, despite his quarrels with traditional psychoanalysis, Alexander's legacy may be in his attitude towards psychoanalysis, characterized by a commitment to scientific study, a willingness to experiment, and a conviction about the role of psychoanalysis within the larger culture.
Enantioselective synthesis of tricyclic amino acid derivatives based on a rigid 4-azatricyclo[5.2.1.02,6]decane skeleton
Authors: Breuning Matthias , Häuser Tobias , Mehler Christian , Däschlein Christian , Strohmann Carsten , Oechsner Andreas , Braunschweig Holger
Published: December 2009

An enantioselective route to four tricyclic amino acids and N-tosylamides, composed of a central norbornane framework with a 2-endo,3-endo-annelated pyrrolidine ring and a 5-endo-C1 or -C2 side chain, has been developed. A key intermediate was the chiral, N-Boc-protected ketone (1R,2S,6S,7R)-4-azatricyclo[5.2.1.02,6]decan-8-one, available from inexpensive endo-carbic anhydride in five steps and 47% yield. The rigid scaffold makes these amino acid derivatives promising candidates for β-turn-inducing building blocks in peptidomimetics and for chiral auxiliaries in asymmetric organocatalysis.
Adults with Auditory Neuropathy: Comparison of Auditory Steady-State Response and Pure-Tone Audiometry
Authors: Jafari Zahra , Malayeri Saeed , Ashayeri Hassan , Farahani Mahdi Azizabadi
Published: December 2009

Background: The relation between the auditory steady-state response (ASSR) and behavioral audiometric thresholds requires further clarification in the case of adults with auditory neuropathy/auditory dys-synchrony (AN/AD). Purpose: The aim of this study was to compare
pure-tone audiometric threshold (PTAT) and ASSR in adults with AN/AD. Study Sample: Sixteen adult participants (32 ears) with AN/AD, ranging in age from 14 to 34 years. Data Collection and Analysis: PTAT and ASSR with high-rate stimulus modulation were measured at four octave
frequencies, 500, 1000, 2000, and 4000 Hz, in each ear. The behavioral auditory thresholds were compared with ASSR estimated thresholds at each frequency. Analyses included comparison of group means and coefficients of correlation. Results: The average pure-tone thresholds revealed
a moderate hearing loss in the AN/AD patients with a focus on the low frequencies. Low-frequency loss audiograms were observed in almost two-thirds of the participants. The estimated auditory thresholds measured by ASSR at all frequencies were substantially higher than the PTAT measures. There
were no significant correlations between the PTAT and ASSR measurements at the 1000, 2000, and 4000 Hz frequencies (p > .05); the correlation between the two measures at 500 Hz (p  =  .029, r  =  0.39) was weak but significant. Conclusion:
There was no significant correlation between the PTAT and ASSR results at the majority of the frequencies usually tested in adults with AN/AD. Although ASSR is not a suitable method to estimate auditory thresholds in this group of patients, perhaps it can be utilized as an adjunct technique
for the differential diagnosis of this disorder.
Laser Milling of Al2O3 Ceramic Based on Deteriorative Layer Controlled
Authors: Wang Xu Yue , Xu Wen Ji , Lei Ming Kai , Guo Dong Ming
Published: December 2009

A new method for laser milling of Al2O3 ceramic based on deteriorative layer controlled is presented in which no assistant gas was used during the laser milling. The new milling technology is developed by means of laser scanning of ceramic surface and forming a deteriorative layer directly. Laser milling parameters are determined through crystal phase’s analysis of the deteriorative layer. The laser milling depth, surface quality, and milling mechanism with different milling parameters were studied systematically on an Nd: YAG CNC laser and multi-layer laser milling experiments were also conducted with optimized processes on the surface of Al2O3 ceramic workpiece. Therefore, the practical experimental results are that each depth of layer milling is between 0.35-0.5 mm and the surface roughness of laser milling reaches to Ra 2-3.2μm. The experimental study has thus provided deeper understanding on laser milling technology for Al2O3 ceramic both in theory and application.
Prediction and Investigation of Surface Response in High Speed End Milling of Ti-6Al-4V and Optimization by Genetic Algorithm
Authors: Alam S. , Nurul Amin A.K.M. , Patwari Anayet Ullah , Konneh Mohamed
Published: December 2009

In this study, statistical models were developed using the capabilities of Response Surface Methodology (RSM) to predict the surface roughness in high-speed flat end milling of Ti-6Al-4V under dry cutting conditions. Machining was performed on a five-axis NC milling machine with a high speed attachment, using spindle speed, feed rate, and depth of cut as machining variables. The adequacy of the model was tested at 95% confidence interval. Meanwhile, a time trend was observed in residual values between model predictions and experimental data, reflecting little deviations in surface roughness prediction. A very good performance of the RSM model, in terms of agreement with experimental data, was achieved. It is observed that cutting speed has the most significant influence on surface roughness followed by feed and depth of cut. The model can be used for the analysis and prediction of the complex relationship between cutting conditions and the surface roughness in flat end milling of Ti-6Al-4V materials. The developed quadratic prediction model on surface roughness was coupled with the genetic algorithm to optimize the cutting parameters for the minimum surface roughness.
Microstructure and Wear Properties of Fe-Cr-C and Fe-Cr-Si-C Clads on Carbon Steel by TIG Surfacing Process
Authors: Azimi Ghasem , Shamanian Morteza
Published: December 2009

In the present study, the surface of St52 steel was alloyed with preplaced powders Fe-Cr-C and Fe-Cr-Si-C by using a tungsten-inert gas (TIG) heat source. Then microstructure of the alloyed surfaces was investigated. Following the surface alloying, conventional characterization techniques, such as optical microscopy, scanning electron microscopy (SEM) and X-ray diffraction were employed to study the microstructure of the alloyed surface. Microhardness measurements were performed across the alloyed zone. The tribological behavior of the coatings was compared in room temperature dry sliding wear tests. It was found that the as-deposited coatings consisted of higher volume fraction of carbides (Cr7C3). No crack formation was found on the coatings. As a result, TIG arc heat source can be used effectively for performing surface alloying on St52 steel with a preplaced powder in order to improve its surface wear resistance.
A Study of Surface Integrity when Machining Refractory Titanium Alloys
Authors: Ginting Armansyah , Nouari Mohammed , Lebaal Nadhir
Published: December 2009

In this paper, the surface integrity is studied when machining the aeronautical titanium alloys. Surface roughness, lay, defects, microhardness and microstructure alterations are studied. The result of surface roughness judges that the CVD-coated carbide fails to produce better Ra value than the uncoated. Lay is characterized by cutting speed and feed speed directions. Feed mark, tearing surface, chip layer formation as built up layer (BUL), and deposited microchip are the defects. Microhardness is altered down to 350 microns beneath the machined surface. The first 50 microns is the soft sub-surface caused by thermal softening in ageing process. Microstructure alteration is observed in this sub-surface. Down to 200 microns is the hard sub-surface caused by the cyclic internal work hardening and then it is gradually decreasing to the bulk material hardness. It is concluded that dry machining titanium alloy is possible using uncoated carbide with cutting condition limited to finish or semi-finish for minimizing surface integrity alteration.
Anisotropic Effect and the Crystals Nature on the Elastic Fields Dispersal Generated in a Three Layers Material
Authors: Brioua Mourad , Benbouta Rachid , Zidani Kamel
Published: December 2009

Semiconductor nanostructures are interesting objects for many microelectronic and optoelectronic applications. Nevertheless, to use them, it is necessary to control their size, their density and their spatial distribution. In the last decade, many researches have been done to control these parameters. One of these researches is the elaboration of a functional substrate inducing a lateral self-organization of nanostructures. The organization driving force is the strain field induced on the surface by a buried dislocations network.
The purpose of this work is the numerical resolution, in the case of anisotropic elasticity, of the problem of a misfit dislocation located between an infinite substrate and two-layer composite. The elastic fields of stresses are calculated for various orientations of the Burgers vector, by inversion of 30x30 arrays of linear equations. The composite NiSi2/Si / (001) GaAs, that made the object of several investigations, is treated like example.
Investigation on the Increasing Material Hardness on Fineblanked Sprocket
Authors: Thipprakmas Sutasn , Chanchay C. , Hanwach N. , Wongjan W. , Vichitjarusgul K.
Published: December 2009

In cold working metal forming process, severe plastic deformation results in changes in the material properties. Earlier researches mainly investigated the rolling and equal channel angular extrusion (ECAE) processes. This study focuses on the fine-blanking process, specially the increasing material hardness on the fineblanked sprocket part. The microstructure around the cut surface is observed and the finite element analysis is done to clarify the mechanism of the increasing hardness as well. The microstructure revealed increasingly compressed and elongated grain structure of the contributed grain flow and orientation, as the blankholder and counterpunch forces increased. This resulted in the increased material hardness around the cut surface. Thus, these results theoretically clarified the mechanism of the increasing material hardness in the fine-blanking process regarding microstructural evolution, with the associated finite element analysis. Therefore, the special characteristic features in the fine-blanking process, result in the pronounced hardening around the fineblanked surface.
Theoretical, Numerical and Experimental Investigation of the Effects of Manufacturing Process Parameters on Thin-Walled Tube Bending Defects
Authors: Taheri Kahnamouei J. , Sedighi Mohammad
Published: December 2009

The aim of this paper is to survey thin-walled tube bending process (without use of mandrel and booster). In tube bending process there are several effective parameters such as wall thickness, outer diameter-to-wall thickness ratio, and centerline bending radius-to-outer diameter ratio. Any mismatch in selecting these parameters would cause defects like wrinkling, variation in wall thickness, and cross section distortion. Firstly, the effects of these parameters on the initiation of the wrinkle, depth of wrinkling, change in wall thickness, and cross section distortion are studied. For this purpose, an FE commercial code has been used to simulate the process. Then, a series of experimental tests have been carried out to verify the results simulation. A comparison between analytical and experimental results shows a reasonable agreement with each other. Based on this comparison, it has been observed that there is a critical bending radius for any tube with a certain radius and thickness, in which the wrinkling begins to occur. For a certain bending angle and radius, it have been observed that the depth of wrinkling, change in wall thickness, and cross section distortion increase with reduction in wall thickness and outer diameter-to-wall thickness ratio
An Analytical Model to Reduce Spring-Back in Incremental Sheet Metal Forming (ISMF) Process
Authors: Vahdati Mehdi , Sedighi Mohammad , Khoshkish Hossein
Published: December 2009

In this paper, spring-back and its effect on geometrical and dimensional accuracy of incremental sheet metal forming (ISMF) process has been studied. The influence of process parameters such as: vertical step size, sheet thickness, tool diameter, feed rate and spindle speed have been investigated. A series of experimental tests have been carried out for a straight groove bead-shape part made of aluminum sheets. A reliable statistical analysis has been carried out to extract the importance of each parameter. The obtained model permits to select appropriate process parameters to reduce spring-back effectively.
Proposal of a New Ultrasonic Welding Technique for Thermoplastic Polymer
Authors: Wu Yong Bo , Sato Takashi , Qiu Jian Hui , Lin Wei Min
Published: December 2009

This paper proposes an alternative ultrasonic welding technique capable of welding plastic parts with different shapes and sizes. In this method, a thin plastic sheet of less than 0.5 mm in thickness is fixed to the ultrasonic vibration body called the horn, and two plastic workpieces to be welded are pressed upon the sheet from both sides at a constant normal pressure. Once the horn starts to ultrasonically vibrate, frictional heat is momentarily generated between the sheet and the plastic workpieces, increasing the frictional temperature to a high level. When the temperature increases to over the melting point of all the materials, the materials melt and eventually are welded after the ultrasonic vibration stops. In the current work, an experimental apparatus was designed and constructed. A series of experiments was subsequently carried out on the apparatus to investigate how the surface roughness of the workpieces, the welding time, and the normal welding pressure affect the actual welding area and the tensile strength of the welded workpieces. The experimental results showed that a bigger welding area and a higher tensile strength can be obtained under the appropriate welding conditions, providing validation of the new welding method.
Hydraulic Bulge Tests of Magnesium Tubes at Elevated Temperatures
Authors: Hwang Yeong Maw , Chuang H.C. , Chen B.J.
Published: December 2009

Evaluation of the formability of tubes is an important issue in tube hydroforming processes. Since tubular materials during tube hydroforming are under a biaxial even triaxial stress state, other biaxial-stress-based testing methods are needed. In this paper, uniaxial tensile tests at different temperatures are firstly employed to evaluate the material properties of magnesium alloy AZ61 tubes. A hydraulic bulge warm forming machine, which is used for hydraulic bulge tests with a fixed tube length, is also designed and manufactured. Using this self-designed testing machine, experiments of bulge tests of magnesium alloy AZ61 tubes at elevated temperatures are carried out. From the experimental results, the bulge formability of the magnesium alloy tubes at different temperatures is discussed.
High Power Density Laser Build-Up Welding with CNC Precision
Authors: Cheaitany Fouad , Peters Thomas
Published: December 2009

The use of laser energy in material processing for boring, cutting and welding has been state of the art for many years [1]. The good focussing ability of the laser allows power densities that are hardly possible with conventional welding processes. Thus, the desired component processing can be carried out on a limited area with low overall power where component and material are subjected to minimum thermal loading. The laser build-up welding process which is particularly suited for low distortion applications, as well as materials that are difficult to weld using conventional methods, is explained in detail. Co2 laser, nd:yag laser and diode laser as established beam sources in laser material processing are compared with newer, innovative beam sources like the fiber laser and disk laser that have been developed in the recent years. Where the possible spectrum of use ranges from small parts to large components weighing tons, the need for a universal handling system is discussed together with laser safety issues. Several industrial applications for laser build-up welding are presented.
Investigation on the Formability of Tailor Welded Blanks with Curved Seams
Authors: Tian Hao Bin , Liu Xiao Hang , Lin Jian Ping , Smith L.M.
Published: December 2009

Tailor welded blanks had been widely used in automobile industries. In this paper, the formability of tailor-welded blanks with curved seams had been studied in experiments, and compared with that of tailor-welded blanks with straight seams. For tailor welded blanks with curved welded seams, the effects of thickness ratio on the limited forming height are the same under various welded seam shape, and the limited forming heights are decreased and then increased with the increase of thickness ratio, which different to that obtained from tailor-welded blanks with straight seam. The reasons that the shapes of welded seam how to influence the formability of tailor welded blank are deduced in the paper. Results show that the shape of the welded seam can change the blank’s deformation condition, which one of the main factors of determining the sheets formability.
Microstructural and Mechanical Characterization of Friction Stir Welded- 1050 Aluminium Alloy
Authors: El Rayes Magdy M. , El-Danaf Ehab , Soliman Mahmoud S.
Published: December 2009

Friction stir welding (FSW) is a fairly recent technique that utilizes a non-consumable rotating welding tool to generate frictional heat and plastic deformation at the welding location in the continuously-fed work piece. In the present investigation this welding process is applied to join 1050 cold-rolled aluminium plates. The effects of varying the welding parameters namely welding speed [56, 90 and 140 mm/min] and tool rotational speed [850 and 1070 rpm] on the mechanical and microstructural properties were studied. Vickers micro hardness results across the weldment showed that the weld nugget hardness is dependant upon the welding speed and the tool rotational speed. Increasing the welding speed at 850 rpm reduced the hardness at the weld nugget, whereas, at 1070 rpm the weld nugget hardness merely did not change. However, the hardness achieved at 850 rpm was constantly higher than that achieved with 1070 rpm irrespective to welding speeds. In the same fashion, the yield and ultimate strengths of the joints were influenced by varying the welding parameters. Increasing the welding speed at 850 rpm reduced both strengths whereas; at 1070 rpm they were almost unchanged. Microstructural study showed that the weld region is composed of unaffected base metal and the stir zoned [weld nugget] which is characterised by a fine equiaxed grain structure. Increasing the welding speed at constant tool rotational speed has caused a slight refinement in the weld nugget's grain size, whereas, decreasing the rotational speed has also led to weld nugget grain refinement.
Towards Tool Path Numerical Simulation in Modified Friction Stir Spot Welding Processes
Authors: Buffa Gianluca , Fratini Livan
Published: December 2009

Spot welding can be considered a very common joining technique in automotive and transportation industries as it permits to obtain effective lap-joints with short process times and what is more it is easily developed through robots and automated systems. Recently the Friction Stir Spot Welding (FSSW) process has been proposed as a natural evolution of the already known Friction Stir Welding (FSW) process, allowing to obtain sound spot joints that do not suffer from the insurgence of typical welding defects due to the fusion of the base material. In the paper, a modified Friction Stir Spot Welding (FSSW) process, with a spiral circular movement given to the tool after the sinking stage, is proposed. A continuum based numerical model for Friction Stir Spot Welding process is developed, that is 2D Lagrangian implicit, coupled, rigid-viscoplastic. This model is used to investigate the distribution of the main field variables, namely temperature, strain and strain rate, as well as the Zener-Hollomon parameter which, in turn, strongly affects the Continuous Dynamic Recrystallization (CDRX) process that takes place in the weld nugget. Numerical and experimental results are presented showing the effects of the process parameters on the joint performances and the mechanical effectiveness of the modified process.
Experimental Models for Assessment of Interfacial Heat Transfer in Dip Soldering
Authors: Nyamannavar Shankargoud , Prabhu K. Narayan
Published: December 2009

The success of a numerical simulation for solder solidification during soldering processes depends on an accurate knowledge of heat transfer phenomenon at the solder/substrate interface. Two experimental setups were designed to study the interfacial heat transfer at solder/substrate interface. In the first method, a cylindrical probe of substrate material was dipped in liquid solder and solder was allowed to solidify around the metal probe. In the second method the test probe was dipped in the bulk solder liquid of sufficiently large quantity and allowed to attain the surrounding solder liquid temperature. Temperature at the center of the probe was measured using thermocouple. Heat flux transients at the surface of the probe were estimated by lumped heat capacitance method. SEM study at the solder/substrate interfacial region for experiments of solidifying solder around the test probe revealed the existence of a clear gap with aluminum substrate. A conforming contact was obtained with copper substrate. The nature of heat flux transients was found to be different in two experiments.
Interfacial Phenomena in Brazing of a Stainless Steel Face Sheet to a Honeycomb Core
Authors: Mehrizi S. , Hadian A.M. , Hadian A. , Vosughi A.
Published: December 2009

One of the difficulties in manufacturing of sandwich honeycomb structures is the proper joining of honeycomb cores to face sheets. In this investigation, vacuum brazing process using BNi-2 brazing alloy was applied for these types of joints. Brazing cycles were performed at temperatures ranging from 1020 to 1050oC under different holding times ranging from 5 to 20 min.
Three different zones were observed in the solidified braze layer. The width of each zone was altered by brazing cycle. The results showed the crucial role of boron element in the brazing alloy in wetting behavior and final products after brazing. The optimum brazing cycle was found to be 1020oC and 5 min holding time followed by heat treating the brazed samples at 600oC for 6 hrs.
Influence of Forming Residual Stresses on the Welding Distortions of Two Thick Plates
Authors: Gallée Sebastien , Martin Antoine , Robin Vincent , Nelias Daniel
Published: December 2009

The manufacturing of the ITER (International Thermonuclear Experimental Reactor) vacuum vessel involves the welding of thick deformed plates. The aim of this study is to investigate the influence of forming residual stresses on the welding distortions of two thick plates. The plates are deformed using a three point rolling process. A first numerical simulation is performed to investigate the residual stresses induced by this process. The forming residual stresses are taken into account as initial conditions to perform the electron beam welding simulation of a deformed plate. This simulation first requires calibrating the heat source. Two welding simulations are then performed: the first one with residual stresses and the second one without. The comparison of the simulation results points out a low effect of the residual stresses on the electron beam welding distortions. As a result, in the next electron beam welding simulations of the vacuum vessel, no forming residual stresses will be taken into account.
Electric Current Pulse Welding of Titanium with 18-10 Stainless Steel
Authors: Grigoryev E.G. , Bazanov V.N.
Published: December 2009

The purpose of the work was to determine the capabilities of the pulse effect of electric current and pressure to produce welded joints of various component parts of different thickness from 18-10 stainless steel and titanium. Application of electric current pulses on the surfaces of contacting metallic conductors leads to considerable changes in the surface structure. Depending on the initial state of the surfaces and parameters of the pulse effect this can result in melting without formation of joints, formation of a strong welded joint with characteristics no worse than those of welded metals, and in destruction of the contact zone. A combination of a short electric pulse with simultaneous application of mechanical pressure in the weld zone causes high-speed deformation of the contact zone. The process of joint formation itself does not cause any appreciable diffusion during welding. The greatest energy emission and the maximal heating occur on the contacting surfaces being welded with the passage of an electric current pulse through the welding zone. Simultaneously with intensive heating, and due to applied pressure, high-speed deformation of materials takes place and a strong welded joint is formed. Optimal parameters for the welding of titanium and 18-10 stainless steel have been determined on the basis of the tests conducted. Investigations into the welding of titanium and 18-10 stainless steel have shown that application of a short electric current pulse and pressure produces stronger welded joints composed of both similar and different metals of considerably different thickness.
Residual Stress Correlation in Two Different Mitigation Techniques Using FEA
Authors: Soul F. , Ateeg M. , Beshay S. , Senfier M.
Published: December 2009

Many techniques were developed to control residual stress and distortion during welding process to minimizes their magnitude in the affected area. Due to complicity to find qualitative analysis for welding residual stress and distortion in real experiment work, the numerical simulation of welding process give a good solution to helpful the process and evaluated extensive analysis. In the present paper two different residual stress mitigation techniques moving cooling spot and moving heating spot were investigated in thin welded sheet structure using FEA. Thermo mechanical analysis and simulation of the processes were performed by ANSYS. The obtained results show different residual stresses behaviour developed during welding, the residual stress magnitude were minimized in both used techniques especially in trailing heat sink welding process. The out of plane distortion results show successfully eliminating of cambering distortion, it is also found that the effective elimination are based on the proper position parameters with respect to the welding heat source.
Intensity of Diffraction of Laser Irradiating a Microparticle in Nanostructure Processing
Authors: Ho Ching Yen , Wen Mao Yu , Ma C.
Published: December 2009

Traditional materials processing in the nanometer range using laser technology is very difficult with conventional optics due to the diffraction limit of the beam wavelength, a near-field technology has been developed to circumvent the diffraction limit, permitting the spot size to be reduced down to 20 nm. In most near-field techniques, this technology is achieved by placing a small aperture or microparticle between the sample and the light source. Therefore this paper will analytically investigate the profile of the intensity for diffraction of laser irradiating an aperture or microparticle in nanostructure processing. Classical electromagnetic wave theory is employed to calculate the intensity for diffraction of laser irradiating a microparticle or aperture. The results will reveal the differences between an aperture and micoparticle for diffraction of laser. The effect of laser parameters on the intensity and distribution of diffraction will be also discussed.
Elevated Temperature Wear of Submicron Al2O3 Reinforced 6061 Aluminum Composite
Authors: Al-Qutub A.M. , Allam I. , Al Hamed A. , Elaiche A.
Published: December 2009

The effects of load and temperature on wear behavior of 6061 Aluminum alloy matrix composite reinforced with 20% Al2O3 (submicron) particulates against AISI 4041 steel disc were studied at elevated temperatures ranging from 25oC to 300oC. Mild and severe wear regions separated by a transition region were observed at all temperatures with a difference of two orders of magnitude between mild and severe wear. The critical loads observed at 100oC, 200oC and 300oC were 40 N (2 MPa), 30 N (1.53 MPa) and 15 N (0.76 MPa) respectively indicating that wear resistance of the composite decreases with increase in temperature. Scanning electron microscopy revealed that wear was accompanied by extensive thermal softening of the matrix, in addition to particulate fracture due to high shear strain generated from the contacts and material transfer to the counterface. The wear rates were reduced in the mild wear regime due to oxidation of the iron counterface and deposition of oxides on the contact surfaces evident by EDS analysis.
EIS Study of Bulk Al-SiC Nanocomposite Prepared by Mechanical Alloying and the Hot Press Method
Authors: Rostamzadeh Taha , Shahverdi H. , Shanaghi A. , Shahrabi T.
Published: December 2009

Metal matrix composites (MMCs) are engineering materials in which a hard ceramic component is dispersed in a ductile metal matrix in order to obtain characteristics such as hardness and corrosion resistance. Corrosion resistance is one of the important properties of nanocomposites; however, the corrosion mechanism of the Al- SiC nanocomposite has not yet been determined. .In this study, bulk Al-5% SiC nanocomposite was prepared using mechanical alloying and the hot press method. Corrosion behavior was then investigated using EIS techniques such as Nyquist and the Bod diagram. A larger charge transfer resistance was found for the Al- SiC nanocomposite by the EIS diagrams, confirming its corrosion resistance in a 3.5wt% NaCl solution.
Development of an Expert Engineering Module for Determination of Ultrasonic Probe Position on the Weld Joint of Plate
Authors: Shahriari D. , Jodaki J , Jandaghi Shahi V. , Darban Falak J
Published: December 2009

Ultrasound based inspection techniques are used extensively throughout industry for detection of flaws in engineering materials. The range and variety of imperfections encountered is large and critical assessment of location, size, orientation and type is often difficult. The research presented in this paper has resulted in a knowledge-based engineering module, which was developed software for determining ultrasonic probe location precisely and detecting of the welded sections completely. The criteria for diagnosing these positions, which have been classified into different groups, included in type of material, thickness, geometry of welded section, couplant material, angle probes and etc. The expert system can display the limits that probe must be moved which caused an inspection welded section thoroughly. This study was conducted using three samples including different materials with V groove welded sections for verifying this expert system. Finally this module is very suitable in Q.C. labs and different industries for detection of flaws.
Simulation and Physical Modeling of Forging Sequence of Bj Type Outer Race
Authors: Mohammadi M.M. , Sadeghi M.H.
Published: December 2009

The outer race of a constant velocity (CV) joint is an important automotive component
that is difficult to be forged because its shape is very complicated and the required precision is high.
Since traditional cold forging methods are not always capable of producing complexly shaped parts,
such parts are often made by processes, which require intense machining operations at relatively
high costs. Thus near net shape forging is an attractive option for producing of outer race. Actual
problems in final ironing sequence are prevention of ductile fracture and surface defects in final
product and true formation of internal ball grooves of the workpiece. In this study Cockroft&Latham
failure criterion was applied to final ironing sequence. Finally physical modeling is down using lead.
In order to investigate the flow of the billet material during forging, the experimentally obtained
section profile of internal grooves as measured by a CMM is compared with simulation based
profile.
Numerical Simulation of Superalloy IN718 during Tube Hot Extrusion
Authors: Sun Chao Yang , Zhang Qing Dong
Published: December 2009

Superalloy IN718 large tube is used in critical jet engine applications, while manufacturing such components, the control of temperature during tube hot extrusion is of paramount importance. To determine the relation between technological factors and the temperature rise, extrusion force during tube hot extrusion of superalloy IN718, a numerical model was developed to for the large tube hot extrusion through die and over mandrel. The constitutive behaviour of the material and friction at the extrusion temperatures are established as a thermoplastic process. In order to investigate the influence of technological parameters of extrusion process on the temperatures rise and extrusion force, then the extrusion variables such as friction factor, ram speed, tool and billet preheating temperature are taking into consideration. Besides tool preheating temperature, other parameters have a great influence on temperature rise of billet during the extrusion process. All of technological parameter of study in this paper have a significant influence on the extrusion force. Moreover, based on the simulation results, the case with tool preheating temperature of 300°C should avoid during the technology making.
Effect of Severe Plastic Deformation on Mechanical Properties of Fe-Ni-Mn High Strength Steel
Authors: Shirazi H. , Nili-Ahmadabadi Mahmoud , Fatehi A. , Hossein Nedjad S.
Published: December 2009

Fe-Ni-Mn martensitic steels show excellent age hardenability but
suffer from embrittlement after aging. Discontinuous coarsening of grain
boundary precipitates was found as the main source of embrittlement. Effect
of cold rolling and equal channel angular pressing on the mechanical
properties of an Fe-10Ni-7Mn steel was investigated. Cold rolling for 20%,
40%, 60%, 80% and 90% and equal channel angular pressing for four
passes through the Bc route were carried out on a solution annealed material
with subsequent aging at 753 K. Hardness measurement, tensile test and
scanning electron microscopy were used to study mechanical properties and
microstructural features of the as-deformed and aged alloys. Improvement in
tensile properties of the as-deformed and aged alloys was found. A tensile
strength of about 1840 MPa along with 3% elongation were determined for
cold rolled by 90% thickness reduction and aged alloy, while conventional
steel shows a premature fracture stress of 820 MPa with zero ductility. It
was also indicated that after heavy cold rolling ductility increases in
comparison to the equal channel angular pressed and aged alloy.
Temperature Changes with Die Profile in Axisymmetric Forward Extrusion Process
Authors: Ajiboye J.S. , Adeyemi M.B.
Published: December 2009

Temperature effect due to varying die opening shapes in the direct extrusion of lead have been numerically simulated and presented. Using upper bound method of analysis the internal heat generation due to plastic deformation and frictional heat at various stages of the extrusion process for different die opening geometry are simulated. A C++ program simulates the deformation and frictional power at die land region which is converted to temperature change using finite difference program. At the extrusion die land region, temperature rises with increasing complexity of die openings geometry with I-shaped section, giving the highest temperature rise, followed by T-shaped section, rectangular, circular shaped die openings with square section die opening, giving the least temperature rise for any given extrusion parameter. The die land zone shows increasing temperature rise with increasing friction coefficient, while increasing friction coefficient has no overall effect on the dead metal zone temperature rise. The proper choice of die land is, therefore, imperative if excessive generation of heat at the emergent section is to be avoided to maintain good quality and metallurgical structure of the product.
Prediction of Tool Life and Experimental Investigation during Hot Milling of AISI H13 Tool Steel
Authors: Nurul Amin A.K.M. , Hafiz A.M.K. , Lajis Mohd Amri , Patwari Anayet Ullah
Published: December 2009

This paper presents the results of experimental investigations conducted on a vertical machining centre (VMC) using spindle speed, feed rate, and depth of cut as machining variables to ascertain the effectiveness of TiAlN insert in end milling of hardened steel AISI H13, under work-piece preheated conditions and hence a statistical model was developed using the capabilities of Response Surface Methodology (RSM) to predict the tool life. Sufficient number of experiments was conducted based on the small central composite design (CCD) concept of RSM to generate tool life data for the selected machining variables. The adequacy of the model was tested at 95% confidence interval. Meanwhile, a time trend was observed in residual values between model predictions and experimental data, reflecting little deviations in tool life prediction. A very good performance of the RSM model, in terms of agreement with experimental data, was achieved. The model can be used for the analysis and prediction of the complex relationship between cutting conditions and the tool life in flat end milling of hardened materials.
Dynamic Simulation and Test Verification of PCB with BGA Chipset
Authors: Cheng Ken Chuan , Wang A Cheng , Huang Jeng Shen
Published: December 2009

Generally, impact and shock to portable electronic products can cause significant functional and physical damage in the form of internal component failure or package-to-board interconnection breakage. Therefore, this paper provides a dynamic simulation of shock impact to investigate the internal stress and strains of a printed circuit board (PCB) with ball grid array (BGA) chipset. The tin balls will be simulated with a minimum element size as 0.0536 mm in LS-DYNA finite element software.
The corresponding strains of dynamic analysis on PCB board will be compared with those of the experimental measurements using the strain gauge. Finally, the model established has values of peak strain and impact duration close to those measured in the actual shock test. The comparison results of the experimental and numerical strain show that the smallest difference is 0.70%. Furthermore, we also investigate the signal curves of experimental error source on the accelerometer and strain gauge. The measurement results show that the capabilities of the repetition and stability both the input signals and output signals are excellent. This result provides researchers in relevant fields with an excellent example and model for further study of PCB with BGA chipsets.
Numerical Simulation and Experimental Study on Corrugated Waist Rail with Universal Rolling
Authors: Ma Jin Hong , Zhang Wen Zhi
Published: December 2009

The rolling process of corrugated waist rail is simulated by explicit dynamic FEM. The
influence of rolling velocity, reduction and the initial thickness on the rolling force is analyzed. The
rolling corrugated waist rail is experimented on the three-stands universal mill of Yanshan
University. At the same rolling condition, the rolling force obtained from experiment is coincident
with the simulation, this proves the theory analysis is correct. Therefore, the rolling parameters
obtained from simulation can be instructive to the production site.
Modelling of Residual Stresses Induced by Turning of 316L
Authors: Valiorgue F. , Rech J. , Hamdi H. , Gilles P. , Bergheau J.M.
Published: December 2009

Residual stresses are very important for the lifetime of pieces in their mechanisms. These kind of damages are mainly caused by mechanical, thermal, and metallurgical affectations of the machined material. To control these affectations, we need to link the cutting parameters to the residual stress state observed onto the workpiece surface and depth. These connections can be made with analytical works, experimental works or numerical works. In our case, it has been chosen to work with a numerical support in order to observe and understand precisely the phenomenon involved during cutting operation. While this way of study is really popular, we proposed to model the residual stress generation in a original way by keeping aside the chip formation. This new approach presented in a previous paper was simple and only use a 2D model. This first model moves thermo mechanical loadings onto the workpiece surface to recreate the relative motion between the tool and the workpiece. The new 3D model, presented in this paper, is now improved with an original friction law. It underlines the impact of each passage of the tool onto the others. The physical properties are thermo dependant and the flow stress model is based on a Johnson cook behaviour.