bluuebunny/crossref_metadata_2025 huggingface dataset:
“Order-Order” Kinetics in Triple-Defect B2-Ordered Binary Intermetallics: Kinetic Monte Carlo Simulation
Authors: Biborski A. , Abdank-Kozubski Rafał Leszek , Pierron-Bohnes V.
Published: September 2014

Triple-defect formation in B2-ordered binary A-B intermetallic compounds results fromthe asymmetry between the formation energies of A- and B-antisite defects. Chemical disorderingin such systems is strictly correlated with vacancy formation, which is the reason for usually veryhigh vacancy concentration. Consequently, Kinetic Monte Carlo (KMC) simulation of processes occurringin the triple-defect systems and controlled by atomic migration via vacancy mechanism mustinvolve complete vacancy thermodynamics – i.e. the simulated system must contain the equilibriumtemperature-dependent number of vacancies. The fully consistent approach based on two differentMonte Carlo techniques has been applied in the present study. The AB intermetallic was modelled withan Ising-type Hamiltonian and KMC simulated for “order-order” kinetics with temperature-dependentequilibrium number of vacancies previously determined by means of Semi Grand Canonical MonteCarlo (SGCMC) simulations. The procedure required in addition the determination of saddle -pointenergies assigned to particular atomic jumps to nn vacancies. Their values were estimated in relationto the nn pair-interaction energies with reference to Molecular Statics simulations performed for NiAlsystem with EAM energetics. The results elucidated the role of triple-defect formation as the atomisticscaleorigin of the experimentally observed surprisingly low rate of the “order-order” kinetics in bulkNiAl.
Direct Punching in Inclined Ultra-High Strength Steel Sheets
Authors: Abe Yohei , Mori Ken Ichiro , Nakanoshita Shigehiro , Kadarno Purwo
Published: September 2014

A direct punching of inclined ultra-high strength steel sheets having low ductility was carried out to improve the quality of the sheared edge. In the direct punching of an inclined sheet, the contact between the sheet and punch became gradual because of touch from the bottom edge of the punch, and thus the sheared portion tended to bend in the latter half of punching. As the strength of the sheet increased, defects such as burr and secondary burnished surface were occurred around the sheared edge due to the low ductility. The range of direct punching for sheared edge without defects was shown for the high strength steel sheets. To prevent the occurrence of defects, a punch having inclined bottom was used. In this punch, the contact with the sheet was changed, the uniform contact with the inclined bottom was given. In the punch having the inclined bottom, the secondary burnished surface in the edge of 980 MPa grade steel sheet was prevented.
A New Approach for Quantitative Evaluation of Bending Components
Authors: Engel Bernd , Kuhnhen Christopher , Mathes Christian , Heftrich Christopher , Frohn Peter , Groth Sebastian
Published: September 2014

During the bending of tubes, specific geometric deviations from the desired shape geometry occur. These deformations comprise cross-sectional deformation, wall-thinning of the outer arc and wall-thickening of the inner arc. During the bending of parts with small bend factors, geometric deviations on the inner arc in form of waves and wrinkles may arise as other typical quality criteria. A quantitative evaluation of those deviations has yet to be defined. Currently, only an instruction for measuring the height of the wrinkles at the inner arc according to DIN EN 13480-4 is known. In this standard, only the two highest wrinkles and the valley in between are included. The characteristics of the wrinkle, especially the flank angle and the rise of deformation are disregarded, although they are responsible for the failure of the bent part. Tool damages can also occur. A development of an evaluation factor to assess deformations in the bow area for bent parts is presented in this paper. In addition, it will be possible to quantify geometric deviations in the bow area. By using the newly developed evaluation factor for geometrical deformations in the bow area, the determination of the quality of the bent part should become more reproducible.
A Validated Analytical Solution for the Two-Dimensional Bending of Aluminium Plates under Creep-Ageing Conditions
Authors: Lam Aaron C. , Lin Jian Guo
Published: September 2014

An analytical method suitable for modelling the creep-age forming (CAF) of doubly curved aluminium plates is presented. This new mechanics model combines an efficient numerical integration method with a robust set of CAF constitutive equations that has been experimentally validated with AA7055 at a CAF condition. Corresponding finite element simulations show good agreement with the analytical results. Using the validated analytical model to investigate a three-stage CAF process (loading, creep-ageing, and unloading), through-thickness strain distributions are studied for aluminium plates that have been subjected to different creep-ageing time. A creep activation point (CAP) is revealed and a correlation is found between the two parameters introduced in this work – the normalised location of CAP, zCAP and normalised bend ratio, β. More specifically, a linear relationship is found between β and zCAP, which indicates that the onset of creep strain, and hence the sizes of the pure elastic core and the outer creep region, can be readily predictable within the limits of study. It is now possible to simulate two-dimensional bending CAF processes for aluminium alloys that have non-spherical precipitates.
Theoretical and Experimental Research on a Method for Producing a Triangular Rosette-Shaped Flange
Authors: Gontarz Andrzej , Pater Zbigniew , Tomczak Janusz , Winiarski Grzegorz
Published: September 2014

The paper presents a new method for forming a hollow shaft with a triangular rosette-shaped flange on its end. The part being investigated is used as a propeller shaft in helicopters. The product must be monolithic, therefore it cannot be produced by methods which consist in joining a flange with a tube. Up till now, such shafts have been produced by machining from solid barstock, the process which generates material losses exceeding 90%. The application of the proposed flanging method results in a significant reduction in both material and labour consumption, which leads to lower production costs. Due to beneficial texture of the shaft flange, shafts produced by this method exhibit better strength properties than shafts produced by machining. The paper presents the results of a numerical analysis of the flanging process, performed using DEFORM-3D software. Also, experimental tests were conducted using a three-slide forging press. Theoretical and experimental results obtained confirm the effectiveness of the new method for forming this part.
On the Damage Criteria and their Critical Values for Flowforming of ELI Grade Ti64
Authors: Depriester Dorian , Massoni Elisabeth
Published: September 2014

Cold ﬂowforming is a chipless forming process that deforms tubular parts by reducing theirouter diameter and thickness while increasing their length. It consists of a rotating mandrel and oneor more rollers that are translated along the tube axis, thus plastically deforming it. Flowforming ofTi-6Al-4V (also known as Ti64) is of great interest for improving the mechanical properties of thematerial, such as yield stress and fatigue strength. However this alloy is known to have poor ductilityat room temperature. Therefore, ﬂowforming of Ti64 without failure or crack is a great challenge. Inthis present paper, the authors have attempted to predict the different failure modes occurring duringﬂowforming. An experimental machine has been built at the Center forMaterial Forming (CEMEF) inorder to monitor the force on the single roller, the torque on the mandrel and the actual rotation speedof the roller as well. Numerous ﬂowforming tests have been performed using different processingparameters, such as working depth, roller feed and initial geometry, in order to investigate the criticalvalues which lead to the failure of the ﬂowformed tube. In addition, numerical simulations of theprocess have been performed using the FORGE FEM solver. The results of the simulations have beenused to evaluate the relevance of usual failure criteria (Crockford-Latham, Rice-Tracey and Oyane).
Numerical Simulation of the Crystallographic Texture Evolution during Hot Extrusion of Oxides Dispersed Strengthened Steels
Authors: Sornin Denis L.S. , Karch Abdellatif , Barcelo Françoise , Logé Roland E.
Published: September 2014

Oxides Dispersed Strengthened (ODS) stainless steels are foreseen for fuel cladding tubes in the coming generation of fission nuclear reactors. In spite of a bcc matrix, those steels present a convenient creep behavior thanks to very fine oxides dispersion. Those grades are currently obtained by Powder Metallurgy (PM). After mechanical alloying with the oxide, the powder is commonly consolidated as seamless tube. On CEA facilities, new ferritic ODS stainless steels are produced by Hot Extrusion (HE). The control of the microstructure after extrusion is a key issue for this grade regarding service conditions. In order to explain the microstructure induced by hot processing, the thermo-mechanical history applied to the material must be taken into account. In this study, the strain and thermal histories are obtained from Finite Element Method simulation. Thus, crystallographic texture development during hot extrusion of ODS ferritic steels is simulated using a Visco-Plastic Self-Consistent (VPSC) model. By comparing the texture predictions with the experimental observations, it is shown that self-consistent model reproduces the extrusion texture, α-fiber, very well in the case of monotonic loading. However, for complexes strain path observed during HE, VPSC results differ from the experimental deformation texture.
Beta-Forging of Titanium Ti6Al4V Alloy Powders: Phase Evolution Modeling and Strain-Rate Relation
Authors: Testani Claudio , Squillace Antonino , Astarita Antonello
Published: September 2014

Ti6Al4V is one of the best known and studied titanium alloy for the optimization of the thermo-mechanical treatments. The Ti-forgings represent a valid opportunity for the aircraft manufacturers and designers because of high tensile and fatigue properties. Nevertheless the total-cost reduction of the manufacturing-chain requires both: the ability to manufacture nearer-shaped components by mean of forging-process-modification and less final machining (material scraps). Even if Ti6Al4V is a well known alloy, any process parameters modification introduced still represents a challenge for the metallurgists and manufacturers.The idea, at the base of the present work, has been the feasibility study of forging experiments in the Beta-field using Hot Isostatic Pressed (HIP) powders billets. The preliminary compression tests has been carried out in laboratory and the results have been validated in a industrial Forging-Workshop. The deformation behavior of Ti6Al4V HIPped powders during high temperature deformation tests is reported. Laboratory compression and tensile tests have been coupled with relaxation tests in order to achieve robust data about strain rate sensitivity m-coefficient and activation energy Q.The obtained results have been fitted for the assessment of generalized exponential deformation law. The final result is a “Dorn model” that takes into account and compares all the results from the three different deformation tests: compression, tensile and relaxation. The deformation tests have been carried out at temperatures ranging from 1173 K up to 1373 K and strain rate from 0,01 s-1 up to about 1 s-1, trying to describe the high temperature complex shape forging operations.Finally the recorded deformation curves has been used for modeling by means of FEM DeformTM code the deformation process and microstructure evolution by means of an Avrami type law.
Hot Spline Forming of Ultra-High Strength Steel Gear Drum Using Resistance Heating
Authors: Mori Kenichiro , Maeno Tomoyoshi , Nakamoto Shohei
Published: September 2014

A hot spline forming process of die-quenched gear drums using resistance heating of a side wall of a cup formed by cold deep drawing and ironing was developed. The side wall having uniform cross-sectional area is resistance-heated by passage of the current in the axial direction, the heated side wall of the drawn cup is ironed and is finally die-quenched. The gear drum was successfully formed and the hardness was between 400 and 500 HV. Not only the formability was improved but also the formed dram was hardly oxidised because of rapid resistance heating.
Study of Formability of Steel Thick Plates for Offshore Structures
Authors: Park Kwang Soo , Kim Sook Hwan , Kim Dong Kyu
Published: September 2014

A jack-up rig or a self-elevating unit is a type of mobile platform that consists of a buoyant hull fitted with a number of movable legs, capable of raising its hull over the surface of the sea. The buoyant hull enables transportation of the unit and all attached machinery to a desired location. Once on location the hull is raised to the required elevation above the sea surface on its legs supported by the sea bed. The legs of such units may be designed to penetrate the sea bed, may be fitted with enlarged sections or footings, or may be attached to a bottom mat. Generally Jack up rigs are not self-propelled and rely on tugs or heavy lift shipsfor transportation.
Formability problems in offshore structure construction where particularly high-strength steels are used for chords and racks. Attainment of mechanical properties is not usually difficult, although procedural trials are advisable. Fatigue cracking is probably the major cause of service failure of jack-up rigs, and the use of high-strength steels, which permits higher static stress limits, can exacerbate this problem. Roll forming process is one of the most widely used processes in the world for forming metals. It can manufacture goods of the uniform cross section throughout the continuous processing. However, process analysis is very difficult because of the inherent complexity. Therefore, it is time-consuming and much money is needed for manufacturing goods. In order to overcome this difficulty, a new computational method based on the rigid-plastic finite element method is developed for the analysis of roll forming process.
Forming Limit Analyses of 590 MPa High Strength Steel Sheet Using Differential Work Hardening Model
Authors: Hakoyama Tomoyuki , Kuwabara Toshihiko
Published: September 2014

A servo-controlled tension-internal pressure testing machine with an optical 3D deformation analysis system (ARAMIS®, GOM) was used to measure the multiaxial plastic deformation behavior of a 590MPa high strength steel sheet for a range of strain from initial yield to fracture. Tubular specimens were fabricated from the sheet sample by roller bending and laser welding. Many linear stress paths in the first quadrant of stress space were applied to the tubular specimens to measure the forming limit curve (FLC) and forming limit stress curve (FLSC), in addition to the contours of plastic work and the directions of plastic strain rates. It was found that the shapes of the measured work contours changed with the increase of work hardening (plastic work). The observed differential work hardening (DWH) behavior was approximated by changing the material parameters and the exponent of the Yld2000-2d yield function (Barlat et al, 2003) as a function of the equivalent plastic strain. The FLC and FLSC calculated using the Marciniak-Kuczyński-type (M-K) approach with the DWH model were in good agreement with the measurement.
Development of Tool Path Correction Algorithm in Incremental Sheet Forming
Authors: Fiorentino Antonio , Feriti G.C. , Ceretti Elisabetta , Giardini C . , Bort C.M.G. , Bosetti Paolo
Published: September 2014

The problem of obtaining sound parts by Incremental Sheet Forming is still a relevant issue, despite the numerous efforts spent in improving the toolpath planning of the deforming punch in order to compensate for the dimensional and geometrical part errors related to springback and punch movement. Usually, the toolpath generation strategy takes into account the variation of the toolpath itself for obtaining the desired final part with reduced geometrical errors.
In the present paper, a correction algorithm is used to iteratively correct the part geometry on the basis of the measured parts and on the calculation of the error defined as the difference between the actual and the nominal part geometries. In practice, the part geometry is used to generate a first trial toolpath, and the form error distribution of the resulting part is used for modifying the nominal part geometry and, then, generating a new, improved toolpath. This procedure gets iterated until the error distribution becomes less than a specified value, corresponding to the desired part tolerance. The correction algorithm was implemented in software and used with the results of FEM simulations. In particular, with few iterations it was possible to reduce the geometrical error to less than 0.4 mm in the Incremental Sheet Forming process of an Al asymmetric part, with a resulting accuracy good enough for both prototyping and production processes.
Single Point Incremental Sheet Forming of Polymer on Computer Numerically Controlled (CNC) Milling Machine Tool
Authors: Rajenthirakumar D. , Sridhar R.
Published: September 2014

The idea of incrementally forming sheet metal with a single point tool, called ‘dieless forming’, was patented by Leszak [1] well before it was technically feasible. There have been many studies, which have lead to the present situation [2-9]. The new processes are attractive because manufacturing sheet metal can be accomplished by any facility having a three-axis cnc mill. Sheet metal spif is an innovative, flexible sheet metal-forming technology that uses principles of layered manufacturing. It transforms the complicated geometry information into a series of parameter of two-dimensional layers and then the plastic deformation is carried out layer-by-layer through the computer numerically controlled. The basic principle of spif (Fig. 1) is that the forming tool moves around the outline of the part along the predefined tool path and extrudes the sheet metal point by point so that the local plastic deformations occur incrementally [8, 10]. The forming tool paths have a great effect on the surface quality, forming time and dimensional accuracy. Although the movement mode of the forming tool is similar to one of the cutters in the cnc milling machine, the forming process based on the plastic deformation and milling process is totally different, so the requirements for the tool paths are different. As a result, there are some specific characteristics which should be considered in forming tool path generation. The goal of this paper is to evaluate the possibility of producing low-cost polymer sheet components by means of spif. Three different thermoplastic materials were incrementally formed on a conventional cnc milling machine. Experiments are conducted to determine the formability, failure modes and significant process parameters. Even though considerable amount of research work has been done in the field, these aspects are not completely defined and only limited number of materials has been tested.
A Cohesive Zone Model for Simulation of the Bonding and Debonding in Metallic Composite Structures - Experimental Validations
Authors: Kebriaei R. , Mikloweit Alexander , Vladimirov I.N. , Bambach Markus , Reese S. , Hirt Gerhard
Published: September 2014

Flexible and economic production of composite structures which include functional layersrequires new manufacturing techniques. Joining by plastic deformation is a powerful technique whichis widely used in production processes to create metal composites [1]. The use of plastic deformationin joining processes offers improved accuracy, reliability and environmental safety [2]. The presentstudy deals with modeling of the bonding and debonding behavior in metallic composite structures.Therefore, a general cohesive zone element formulation in the framework of zero-thickness interfaceelements is developed. This enables the accurate and efficient modeling of the interface based on aninterfacial traction-separation law. The paper is concluded by a detailed description of the processsimulation and a comparison of its results with experimental data.
Adhesion Strength Study of Silicone Rubber Compounds to Nylon 66
Authors: Ou Hui Bin , Sahli Mohamed , Barrière Thierry , Gelin J.C.
Published: September 2014

In recent years, multi-component injection molding has largely developed in the industries. During the manufacturing process, the critical challenge is in achieving an optimum adhesion between the two materials. This study examines the influence of curing kinetics on the interfacial adhesion strength between a silicone rubber and nylon 66 using a rotational rheometer. The evolution of adhesion strength of assembly during the curing behaviour of silicone rubber was measured by tensile test at different curing temperature and different curing time. The results showed a significant increase in adhesion was obtained while either the curing temperature or the curing time increased.
In this study, the rheological property of silicone rubber fluid has been also determined by the rotational rheometer. In addition, the kinetics of the curing reaction of silicone rubber has been studied by differential scanning calorimeter.
Effect of Inter-Metallic Phases on the Bonding Strength and Forming Properties of Al/Mg Sandwiched Composite
Authors: Saleh Haitham , Reichelt Stephan , Schmidtchen Matthias , Schwarz Friederike , Kawalla Rudolf , Krüger Lutz
Published: September 2014

Composite sheet of Twin Roll Cast (TRC) AZ31-Mg alloy and industrial pure Al-1050 was fabricated as Al/Mg/Al with a hot roll bonding process. As the diffusion zone at the interface between the layers plays a crucial role in the formation of bonding strength and formability of clad sheets. It is important to describe the processes of inter-diffusion layer generation in order to assess the abilities of the laminate composites for further processing. Thus, the aim of this study was to investigate the development of the bonding strength, microstructure and mechanical properties of the bonding interface directly after roll bonding and additionally post-annealing processes. Microstructure characterization techniques such as optical and scanning electron microscopy including energy dispersive X-ray analysis (EDX) were applied to investigate the bonding area. No inter-metallic phases were present directly after the roll bonding process. The creation and growth of Al2Mg3 and Al12Mg17 phases were apparent after annealing at temperatures of 250 to 400 °C at different times ranging from five to 120 minutes. The results prove that the growth rate of inter-metallic phases increases considerably with an increase in the annealing temperature. The micro-hardness of the interface-area was also investigated. It was observed that the two inter-metallic phases were significantly harder than the substrate Mg and Al. In order to examine the influence of the inter-metallic phases on the resulting bonding strength after the annealing process, the shear bonding strength test has been conducted for different samples that were annealed at different heat treatment conditions. The results indicate that the optimum annealing temperature is 200 °C leading to a maximum bonding strength. Moreover, the mechanical properties of the composite after roll bonding and post annealing were determined by means of room temperature tensile test. The fracture mechanism after tensile test was also discussed.Keywords:Rollbonding,Al/Mghotrollbonding,TwinrollcastAZ31,bondingstrength
Identification of Defects of Stainless Steel Sold with Brand Names, by Studying their Surface Thin Films with Scanning Electron Microscope (SEM)
Authors: Habibullah Pervaiz
Published: September 2014

In the present paper, we have studied the thin films formed on the commercial stainless steel sold under different brand names in Pakistan with the help of SEM, EDX and XRD and have further investigated that how such stainless steels lose their brightness and become dull. A sample of recycled stainless steel melted in induction furnace was taken for study. The analysis of the layer formed is as follows: wt. %, C = 6.55, O = 6.20, Na = 0.47, Mg = 0.31, Al = 2.28, Si = 1.23, Cr = 15.42, Mn = 1.06, Fe = 59.58, Ni = 6.91 Total = 100, Atomic %, C = 21.02 O = 14.93, Na = 0.79, Mg = 0.49, Al = 3.26, Si = 1.68, Cr = 11.43, Mn = 0.74, Fe = 41.12, Ni = 4.53. Stainless steel has austenite structure, is non magnetic and forms fine passive film of Cr (III) oxide, (Cr2O3) which prevents surface corrosion and avoids further corrosion from spreading in metal’s internal structure. Mn and Ni stabilize austenite structure. XRD spectra show presence of αFe2O3 and Cr2O3 and spinal oxides in the film formed on the sample taken for study. SEM images show how this thin film tears.

In a sound stainless steel, the film formed is too thin to be visible and metal remains lustrous. The film quickly reforms when surface is scratched (passivation). Mostly stainless steel is recycled and average stainless steel objects manufactured and marketed are composed of above 60% recycled material. Oxide spinals of Mn, Ni, Cr with iron oxide are not very resistive to the corrosion. Recently Duplex stainless steel has been manufactured which contains 50:50 austenite and ferrite and have twice the strength compared to austenite stainless steel.
Keywords
Recycle stainless steel, composition of thin film with EDX, SEM images, investigation on αFe2O3 and Cr2O3 spinals.
In the present paper, we have studied the thin films formed on the commercial stainless steel sold under different brand names in Pakistan* with the help of SEM, EDX and XRD and have further investigated that how such stainless steels lose their brightness and become dull. The sample is austenitic stainless steel.
Slab Analysis and FEM Simulation on Rotating Compression Forming of Double-Layer Clad Cylinder under Constant Shear Friction
Authors: Tzou Gow Yi , Weng Sen Chyi , Kuo Bor Lih
Published: September 2014

The friction caused power losses and bulging deformation are always inevitable. The rotating compression forming can reduce the compression force and bulging deformation in metal forming. Furthermore, the bounded double-layer metal material is able to have advantage in proper material cost saving and meeting the required strength for customer. Accordingly, this present study proposes the analysis based on Slab Method (SM) and Finite Element Method (FEM) under constant shear friction to predict the compression force and the rotating moment in the rotating compression forming. Moreover the bulging deformation profiles, the effective stress, the effective strain, the velocity field, the compression force, the rotating moment, and the twist angle can be obtained from FEM simulations. It is also shown that the predicted results have the same trend to verify the acceptance of analysis models.
Axial Crushing in a Novel Technique of Thin-Walled Tube
Authors: Elyasi Majid , Moradpour Amin , Montazeri Saharnaz
Published: September 2014

Thin-walled tubes have always considered as energy absorption systems by researchers. This paper presents a new technique for energy absorption system which is simpler than other designs in production. This novel model is a thin-walled tube with perforation. During manufacturing process, equal numbers of holes are created in rows and columns in order to increase the energy absorption ability. In this article two different workpieces with the same geometry, one with holes and the other one with grooves, are compared to validate the model in accordance with other presented ones. For this purpose, specimens were modeled in finite element software ABAQUS with the same conditions and the amount of energy absorption, the initial decay, and the weight ratio of energy absorption (SEA) were evaluated. Then results which obtained from simulation are compared with experimental ones. Results confirmed that specimens with perforation have better decay symmetry rather than ones with grooves. In addition, force absorption in workpieces with hole is as twice as ones with grooves. The amounts of absorbed energy and SEA in workpieces with perforation are 56% and 46% more than workpieces with grooves, respectively.
Production of Special Tubes with a Variety Cross-Sectional Shapes by Bunch Drawing and Fluid-Mandrel Drawing
Authors: Yoshida Kazunari , Yokomizo Daichi , Komatsu Takaaki
Published: September 2014

Recently, special tubes for high efficiency heat exchangers, high functionality electrodes, and super-micro medical needles have attracted attention. In order to produce such special tubes, however, a special processing method or tool is required.
In this study, fabrication of special tube by bunch drawing and fluid-mandrel drawing were attempted. And it was revealed that the fabrication of special tubes with a variety of cross-sectional shape is possible, when a bunch of tubes, or a tube of large diameter in which a number of fine tubes are inserted, is drawn.
Presumption of cross-sectional shapes after bunch drawing was examined by FE analysis. Cross-sectional shapes and the distribution of Vickers hardness which has relation to equivalent strain were compared between tubes obtained virtually by FE analysis and fabricated actually in this study. It was found that they correspond very well and FE analysis is useful for the presumption of cross-sectional shapes after bunch drawing.
Meanwhile, downsizing of medical needles and heat exchanger tubes has been required from the market. So it is necessary to fabricate an inner-grooved fine tube with thin wall-thickness, and at that time the inner grooved geometry must be homothetic.
Hollow sinking was carried out to reduce the diameter of a tube. And cross-sectional shape, groove geometry, and the change of wall thickness after processing were examined. In hollow sinking, increase of wall-thickness, change of inner groove geometry, and poor inner surface quality were found.
Therefore, newly-devised fluid-mandrel drawing was applied. And it was revealed that it is possible to obtain an inner grooved tube of which groove shape is nearly similar to that of pre-processed tube, even after the processing of diameter reduction. Also, it was clarified that the production of a medical painless needle of 0.2mm in diameter by fluid-mandrel drawing was possible.
Research on Wrinkling Behavior in Tube Hydroforming with Axial Feeding
Authors: Hu Zhu Lin , Yang Lian Fa , He Yu Lin
Published: September 2014

Tube hydroforming (THF) is one of metal forming technologies which has been widely used to manufacture complex hollow workpeices. In THF, a variety of failures may occur and one of them is wrinkling. But recent researches show that wrinkling may be used as a preforming process to improve the formability of tubes. In this paper, a new geometry-based wrinkling indicator is proposed to evaluate the wrinkling level in THF and the wrinkle evolution diagram (WED) based on the shape change of the wrinkles is presented to display the four-stage evolution of the useful wrinkles. The wrinkling levels in THF with axial feeding under various loading paths are predicted respectively via finite element simulation, the influence of loading paths on the wrinkling behavior is investigated, and the evolving stages of the useful wrinkles is revealed via the proposed WED. The results indicate that the proposed wrinkle indicator can distinctly evaluate the wrinkling level, the wrinkling level under pulsating loading path is higher than that under polygonal linear one and four-stage evolution of the useful wrinkles could be evidently demonstrated via the WED.
Notation
Application of Regression Trees in Optimization of Metal Forming Process
Authors: Regulski Krzysztof , Szeliga Danuta , Kusiak Jan
Published: September 2014

Application of sensitivity analysis in optimization of process parameters of production processes for innovative materials, e.g. dual phase steel, requires deterministic model of thermomechanical processes and large datasets that covers whole surface of results. Difficulties in optimization of process parameters correspond with large number of control variables, which should be considered in the technology design. Furthermore, conduction of such analysis takes the great computational cost. Presented work concerns possibility of application of regression trees, especially CART model, in preliminary analysis for sensitivity analysis. Use of data mining algorithms enables acquiring of preliminary, rough results: relationships among parameters of the hot rolling process of dual phase steel strips and rules of optimization of this process, it also does not require any apriori knowledge about thermomechanical processes.
Artiﬁcial Bee Colony Algorithm Used for Solving some Inverse Problem in Solidiﬁcation of the Binary Alloy
Authors: Hetmaniok Edyta
Published: September 2014

Aim of the paper is to solve the inverse problem in solidiﬁcation of binary alloyby applying the Artiﬁcial Bee Colony algorithm. Considered inverse problem consists in recon-struction of the heat ﬂux and the distribution of temperature in case when the temperaturemeasurements in selected points of the alloy are known and is mathematically modeled be meansof the heat conduction equation with the substitute thermal capacity and with the liquidus andsolidus temperatures varying in dependence on the concentration of the alloy component. Fordescribing the concentration the lever arm model is applied and for minimizing a functional,constituting the crucial part of the procedure, the ABC algorithm is used.
A Multi-Objective Optimization of a Porthole Die Extrusion for Quality and Sustainability Issues
Authors: Ciancio Claudio , Varrese Claudia , Ambrogio Giuseppina , Filice Luigino , Musmanno Roberto
Published: September 2014

Nowadays manufacturing companies have to face conflicting issues continuously. Solving this type of problem means finding solutions that ensure a fair compromise between different objectives. In this work, a porthole die extrusion is considered as a specific case study. Usually, the main objective of this process is to find the combination of input parameters that allow the product quality to be maximized. However, product quality is not the only variable that companies have to take into account. In fact, it is also necessary to design the process in an efficient and sustainable way in order to reduce process cost and environmental impact. To this purpose, in this study the conflicting aims of product quality maximization and energy assumption minimization are considered and optimized. To pursue this aim an experimental investigation was executed, in order to build a preliminary database. The decision variables are the profile thickness and the process velocity. During the tests, the punch was measured in order to quantify the absorbed power along with the environmental impact of the process for changing conditions. In the same way, the mechanical properties of the extruded profile were measured by means of a tensile test, in order to assess the product quality. To solve this kind of problem the use of multi-objective optimization techniques is required in order to find the set of Pareto optimal solutions from which a single configuration will be selected according to specific business needs.
Effect of Secondary Cooling on Microstructure, Texture and Properties of 1.2wt% Si Non-Oriented Electrical Steel Processed by Twin-Roll Strip Casting
Authors: Zhang Yuan Xiang , Wu Li Guo , Xu Yun Bo , Wang Yang , Chen Li Qing , Yu Yong Mei , Wang Guo Dong
Published: September 2014

The influence of different secondary cooling conditions (air cooling and water cooling) on microstructure, texture and properties of Fe-1.2wt%Si non-oriented silicon strips prepared by twin-roll strip casting were studied. Specimens were examined by OIM, EBSD and X-RD. The microstructures obtained by water cooling are more homogeneous and coarse in grain size than that obtained by air cooling. The dominant {100} texture can be observed in the case of water cooled, while the air cooled strip show a diffuse texture characteristic. The annealed sheets subjected to water cooling than air cooling show higher permeability and lower core loss due to the presence of relatively larger grain size and more ideal fibre components such as Goss and Cube., It seems that rapid secondary cooling of as cast strips can furtherer optimize the microstructure and texture prior to cold rolling and then substantially the final magnetic properties of 1.2wt% Si non-oriented silicon steels.
Temperature Monitoring during Laser Beam Forming of Steel Sheets
Authors: Akinlabi Stephen , Akinlabi Esther Titilayo
Published: September 2014

Laser Beam Forming is a flexible manufacturing process with great promise for sheet and metal forming, hence, considered as a novel manufacturing method for forming and shaping of metallic components. Being a thermo-mechanical forming process that enables parts or components to be formed with external heat of a laser beam, it is important to monitor and measure the temperature during the laser forming process in order to ensure the integrity of the processed components. This study reports on the temperature monitoring and measurement during laser beam forming process of steel sheets. The experimental design followed the L-27 Taguchi Orthogonal Array. The temperature of nine sets of samples laser beamed formed at different process parameters were monitored using the thermocouple data logger. The temperature for all the components formed at the nine parameter windows were analysed during the process. Hence, it was observed that the measured temperature increases with the increasing line energy during the laser beam forming process.
A New Rolling Model for Three-Roll Rolling Mills
Authors: Overhagen Christian , Mauk Paul Josef
Published: September 2014

During the last 90 years, a lot of works have been published about rolling theories for the two-roll rolling process (2RP). In the last decades, the three-roll process (3RP) has become a significant technique in the production of wire rod and bars, as it allows to cover a wide range of finished dimensions with one pass design, or to realize very close tolerances, depending on the pass design method used (free size rolling or high precision rolling). Horihata and Motomura [2] made use of the upper bound theorem to construct a method for spread calculation, but up to now, a straightforward mathematical method for calculation of stress distribution, roll forces, torques and forward slip is still missing. The present paper aims at a transfer of the slab method, which is well-known and established for the 2RP, to the 3RP. After the rolling theory for flat passes is introduced, Lendl’s equivalent pass method is transferred to the 3RP, which allows the calculation of section passes. Computational results show, that roll forces, torques and forward slips can be calculated under inclusion of elastic stand feedback and interstand tensions. Therefore the model can be used for roll speed set-up to minimize interstand tensions, which is of great importance for the rolling industry.
Effect of Acid Treatment on Mechanical Performance of Polyvinyl Alcohol/Halloysite Nanocomposites
Authors: Fujii Kohei , Nakagaito Antonio Norio , Takagi Hitoshi
Published: September 2014

Halloysite is one of clay minerals (a new family of crystalline aluminosilicates), and has a nano-tubular structure similar to carbon nanotubes. The typical sizes of the halloysite are 50 nm in outer diameter, 15 nm in inner diameter, and 500-1000 nm in length. This paper deals with mechanical properties of PVA/halloysite nanocomposite films which were fabricated by a casting method. Sulfuric acid surface treatments were performed on halloysite to improve its interfacial adhesion bonding between halloysite and PVA polymer matrix. The effect of acid surface treatment on the mechanical performance was also examined. In the case of PVA/untreated-halloysite composites, the tensile strength was decreased; on the other hand Young’s modulus was increased compared with those of neat PVA. It was found that the sulfuric acid treatment time played an important role in the mechanical performance of the PVA/halloysite nanocomposites.
Study of Nanostructured Composites Using the Sclerometry Method
Authors: Lvova Natalia , Perfilov Sergey , Useinov A.
Published: September 2014

A comparative study of the mechanical properties of the extruded and flattened nanostructured composites Al-C60 has been made using two different methods of destructive and non-destructive testing: tensile and compression macro-tests and sub-micron range sclerometry (scratch test). Direct correlation was found between the dominant types of deformation during scratching and the type of “stress-strain” dependencies. The results are useful for understanding the extrusion process and quality control at different load scale.
Experimental Study on Pounding between Structures during Damaging Earthquakes
Authors: Jankowski Robert , Seleemah Ayman , El-Khoriby Saher , Elwardany Hytham
Published: September 2014

Mutual pounding between structures during earthquakes may cause serious structural damage. The aim of this paper is to show the results of a shaking table experimental study focused on pounding between structures in series under several earthquake excitations. The experiments were performed using three tower models with different configurations and different gap distances between them. In the first stage of the study, one rigid tower was installed between two flexible structures, while later on, the flexible tower was located between two rigid structures. The results of the study show that pounding observed during damaging earthquakes might affect the behaviour of structures significantly. It was observed that the rigid towers are more influenced by pounding than the flexible structures. Moreover, the optimal gap size was found to be either the distance which prevents pounding (and therefore prevents from damage) or the zero gap.
Definition of a Constitutive Material Model for Progressive Failure Analysis of Composite Laminates
Authors: Riccio Aniello , di Costanzo C. , di Gennaro P. , Scaramuzzino F.
Published: September 2014

The aim of this work is to introduce a novel constitutive material model for the progressive failure analysis of composite laminates able to predict the Gradual degradation of laminates up to their complete failure. As a relevant added value with respect to state of the art constitutive models, the presented model uses energy considerations to avoid mesh and time-step dependences. In order to prove its effectiveness and accuracy, the proposed material constitutive model has been implemented in the FE software ANSYS© as a User defined material subroutine (USERMAT) and used to simulate the mechanical behavior of an Open Hole Tension specimen. The obtained numerical results have been compared to experimental literature data and to the numerical outputs of Instantaneous and Standard Gradual Degradation Models.
Fatigue Characteristics of Nonferrous Bolts at Elevated Temperature
Authors: Hashimura Shinji , Torii Tetsuya , Otsu Takefumi
Published: September 2014

In order to investigate fatigue characteristics of nonferrous bolts at elevated temperature, fatigue tests of bolted joints which were tightened with three kinds of nonferrous bolts were been conducted at 100°C atmosphere. The test bolts were made of A5056 aluminum alloy and AZ31 and AZX912 magnesium alloy. Creep tests of the bolts at 100°C atmosphere were also conducted. The results showed that the fatigue limit of A5056 bolt was the highest of all regardless of the ambient temperature. The fatigue limits of AZ31 bolt and AZX912 bolt also were a half of the fatigue limit of A5056 bolt at both ambient temperature. Bolt clamping force losses due to creep deformation were observed for all bolts during fatigue tests at elevated temperature. Hence as additional tests, the creep tests which was controlled either the tensile force or the displacements respectively were conducted. As the results it was seen that the clamping force losses for all bolts were remarkably large although the each creep deformation was different for each bolt material. Therefore the results indicates that we have to pay attention to the clamping force reduction due to creep deformation if we use the nonferrous bolt in high temperature.
Evaluation of Crack Tip Stress Field Using Combination of Advanced Implementation of Over-Deterministic Method and FE Analysis
Authors: Sobek Jakub , Pail T. , Veselý Václav
Published: September 2014

Creation of an automatic utility to determine the values of coefficients of higher order terms of Williams power series by usage of over-deterministic method applied to results of finite element analysis is a main goal of this research. The developed procedure based on the support of Java programming language considerably simplifies analyses on optimization of selection of FE nodal results for improvement of accuracy of the near-crack-tip fields’ approximation using Williams series.
Numerical Simulation of Modified Compact Tension Test Depicting of Experimental Measurement by ARAMIS
Authors: Holušová Táňa , Seitl Stanislav , Canteli Alfonso Fernández
Published: September 2014

The paper is focused on the determination of mechanical fracture parameters from the modified compact tension test applied to the cement-based composites. The experimental measurement was carried out by means of the ARAMIS equipment. The numerical study is performed by ATENA 2D software (based on a cohesive law for crack propagation) taking the material parameters for numerical study from the standard compression test. The experimental and numerical results are discussed and compared with the help of basic fracture parameters and Load – COD (crack open displacement) diagrams.
Analytical 1D Model of Delamination Development and Strength of Layered Composite Beam in Post-Buckling
Authors: Pavelko Vitalijs
Published: September 2014

1D nonlinear model of a thin plate (or beam) with delamination was developed earlier. Large deflections and membrane strains of a plate in buckled state, as well as the strain energy described using elliptic integrals. The Griffith-type energy condition was used as a criteria of delamination propagation. The analysis of the destruction of the plate was performed depending on the geometrical dimensionless parameters of a plate and the material strength performance. Here the mentioned model is extended to the general mode of delamination and it allows to describe the post-buckling stage and damage propagation. Model application as a base for the alternative determination of the interlaminar fracture toughness of the layered composites is indicated.
Stress Analysis of Cracked MMCs with Lamellar Microstructure
Authors: Kashtalyan Maria , Sinchuk Yuriy , Piat Romana
Published: September 2014

Stress fields in a single-domain sample of MMC containing multiple cracks in the ceramic layer are investigated using a direct analytical method and finite element modeling.
A Technique for Detection and Sizing of Cracks on Plate Structures Using Piezoelectric Transducer Networks
Authors: Zou F. , Aliabadi M.H.
Published: September 2014

In this paper, a technique for the detection and the sizing of cracks on isotropic plate structures is presented. The generation and the reception of the detection signals – Lamb waves – are made possible by piezoelectric transducers. The presence and the length of cracks are found by the method of triangulation using signals scattered by crack tips. The practicability of the technique is then assessed by a numerical experiment.