bluuebunny/crossref_metadata_2025 huggingface dataset:
Plasticity-Related Microstructure-Property Relations for Materials Design
Authors: McDowell David L. , Choi Hae Jin , Panchal Jitesh , Austin Ryan , Allen Janet , Mistree Farrokh
Published: March 2009

Design has traditionally involved selecting a suitable material for a given application.
A materials design revolution is underway in which the classical materials selection approach is
replaced by design of material microstructure or mesostructure to achieve certain performance
requirements such as density, strength, ductility, conductivity, and so on. Often these multiple
performance requirements are in conflict in terms of their demands on microstructure.
Computational plasticity models play a key role in evaluating structure-property relations
necessary to support simulation-based design of heterogeneous, multifunctional metals and alloys.
We consider issues related to systems design of several classes of heterogeneous material systems
that is robust against various sources of uncertainty. Randomness of microstructure is one such
source, as is model idealization error and uncertainty of model parameters.
An example is given for design of a four-phase reactive powder metal-metal oxide mixture for
initiation of exothermic reactions under shock wave loading. Material attributes (e.g. volume
fraction of phases) are designed to be robust against uncertainty due to random variation of
microstructure. We close with some challenges to modeling of plasticity in support of design of
deformation and damage-resistant microstructures.
Continuum Damage Model of Creep-Fatigue Interaction in Ni-Base Superalloy
Authors: Yeom Jong Taek , Lee Chong Soo , Kim Jeoung Han , Lee Dong Geun , Park Nho Kwang
Published: March 2009

A methodology for evaluating and predicting component lives in creep-fatigue interaction
region was investigated for Waspaloy. A unified viscoplasticity constitutive equation including
multi-back stresses was used to describe cyclic material behaviors. Also, a continuum damage model
coupling with the creep-fatigue damage rules was established based on the analysis of creep and low
cycle fatigue behavior. Multi-axial fatigue and creep equivalent stress concepts were employed to
predict three dimensional component lives. Notched cyclic tests under various stress conditions in the
creep-fatigue interaction region were carried out to validate the life prediction methodology with
FEM simulation based on the continuum damage model. The comparison of experimental data and
prediction results indicates that the continuum damage model is a powerful approach for the
prediction of component lives.
Elastic-Plastic Dynamic Response of the Tube with Free Boundary Condition Subjected to Impact
Authors: Lu Guo Yun , Zhang Shan Yuan
Published: March 2009

Some experimental results of the free-free tubes laterally impacted by the missile were
given and the finite element program LS-DYNA was used to simulate this dynamic response process.
The instantaneous deformation of the circular shell given by experiments and computer simulation
were compared and discussed. It can be seen that when the impact occur the local dents firstly appear
at the beginning of impact. With time increase, the depth of the dents increase, the scope of the
deformation of the tube wall is enlarged; the total stiffness of the cross-section of the tube is weaken
and decreases at the impact point, the beam-like bending deformation take place and the rigid-body
translations occur. Through the computer simulation the exchanged energy between the missile and
the tube were acquired. The impact energy of the missile is transferred to internal energy and kinetic
energy of the tube. The ratio of the internal energy with the kinetic energy of the tube is great for the
weakness rigidity of the tube wall, which is opposite to that of a free-free beam. This research made
us deeply understand the character of the response when studying the elastic-plastic behavior of the
free circular shell under intense dynamic loading.
Three Modes of Penetration Mechanisms of A3 Steel Cylindrical Projectiles Impact onto 45 Steel Plates
Authors: Chen X.W. , Zhang Fang Ju , Liang Bin , Xie Ruo Ze , Xu Ai Ming
Published: March 2009

For researching the terminal ballistic effect of the Fragment Simulation Projectile (FSP),
the experiments that A3 steel cylindrical projectiles of 25mm diameter impacting 45 steel plates are
conducted. The intensity of A3 steel is less than that of 45 steel. In the velocity ranges of 200m/s～
800m/s, Taylor impact, petal-cap failure of Sunflower alike and plugging perforation are observed,
respectively. Complicated material failures of projectile and target conflict with the various
penetration mechanisms.
Automatic Approach on Derivation of Loading Path Using Adaptive Finite Element Analysis Simulation Method
Authors: Heo Seong Chan , Kim Jeong , Kang Beom Soo
Published: March 2009

Loading path is one of the most influential parameter in tube hydroforming(THF) process.
Load history has a major effect on failures such as buckling, necking, bursting, and so on. Because
loading conditions that consist of axial feeding and internal pressure are imposed simultaneously.
Therefore suitable loading path should be determined to prevent onset of failures i.e. bursting on final
products. This paper deals with the procedure on determination of the loading path in order to ensure
the robustness of the final products after the THF. In order to verify the availability and feasibility of
the proposed methodology a subframe model of engine cradle module in automotive is implemented.
In this study, thinning ratio and forming limit stress diagram is used to demonstrate the improvement
of the finished product. The result shows that the developed algorithm has successfully promoted the
effectiveness and feasibility in the THF. Consequently, it is shown that the automatic approach on the
determination of loading condition which is proposed in this paper will provide a valuable method to
satisfy the increasing practical demands for designing process condition in THF.
Development of 3-Dimensional Compression Device and its Application to Clarification of Densification Behavior of Urethane-Foam
Authors: Mimura Koji , Umeda Tsutomu , Riku Isamu , Yamashita Kiichi
Published: March 2009

This paper deals with the results of three dimensional compression tests carried out for
high stiffness urethane foams (Penguin-foam, Sunstar Engineering Ltd.), and also deals with the
constitutive modelling base on Shima-Oyane’s consolidation condition for the tested foamed
urethane. Three kinds of urethane foams, relative densities of which were 0.1, 0.2 and 0.33, were
employed in the experiments. Like metallic porous materials, the tested urethane foams show the
strong plastic-compressibility. On the other hand, in modelling, unlike metallic porous materials,
the identified material constants for different density foams do not take the same (or unified) values
but take the different values when Shima-Oyane’s constitutive model is assumed. Furthermore, the
experimentally derived stress-relative density curves could not be satisfactorily described by
Shima-Oyane’s original constitutive model; the experimental stress-relative density curves show
stronger work hardening as compared with the simulated ones especially in the large deformation
stage. To avoid those inconvenience, in this paper, a modified Shima-Oyane type constitutive
equation was also proposed, and it was shown that the proposed model could well express both the
low work hardening area of the stress-relative density curves at the initial deformation stage and the
strong work hardening area at the final deformation stage by supposing the stress restriction at
initial deformation stage due to the buckling of cell walls of each foam, and the rapid stress increase
at the large deformation stage caused by the successive contact and the friction between the bent
cellular walls, respectively.
The Static and Dynamic Fracture Test of X70 Pipeline Steel
Authors: Yang Zheng , Kim Chang Boo , Cho Chong Du , Beom Hyeon Gyu , Ren Bin
Published: March 2009

The Charpy V notch specimens of X70 pipeline steel with different notch orientation are
tested under the static and dynamic conditions at different temperatures. By analyzing the load versus
displacement curves and fracture appearances of specimens the relation of fracture behavior and
loading rate is investigated. The maximum load increases and the displacement corresponding to
maximum load reduces with test temperature decreasing. Both under the static conditions are larger
than that under the dynamic conditions. The fracture sections of all test specimens are reduced in the
thickness direction and quantity reduced depends on the load rate, notch orientation and test
temperature. At the higher temperature, delamination cracks are found on the fracture surface both
under the static and dynamic conditions, which are perpendicular to the thickness direction in T-L
specimen and perpendicular to the main crack propagation direction in T-S specimen. Influence of
loading rate on the delamination crack size and amount is obvious. The fracture initiation energy and
total fracture energy increase with test temperature increasing. Influence of loading rate on the total
fracture energy is unobvious at the higher temperature, but is obvious at the lower temperature. So the
loading rate effects on total fracture energy are relevant to test temperature and notch orientation.
Investigation on a Mn-Ti High Strength Steel
Authors: Yi Hai Long , Du Lin Xiu , Wang Guo Dong , Liu Xianghua
Published: March 2009

By controlled rolling and cooling process, a Mn-Ti high strength steel with yield
strength on the order of 700MPa had been developed successfully. The microstructure consists of
fine lath shaped bainite and ferrite. The strengthening factors of this steel are attributed to the tiny
interlocked distribution of bainite lath and titanium carbide precipitation. When the amount of
bainite is more than 70%, the yield strength of steel is higher than 700MPa, and good mechanical
performances are obtained. As a result of presence of finely dispersed bainite slabs the plasticity
of steel is improved, with the steel’s elongation being about 19%. Many tiny TiC precipitates are
observed under transmission electron micrograph, and these particles result in precipitation
strengthening.
Fracture Properties of Softwood under Mode I Loading Perpendicular to the Grain
Authors: Li Ming Bao , Cao Jun , Zheng Shi Qiang
Published: March 2009

Fracture properties of softwood under mode I loading perpendicular to the grain are studied
in this paper. The stress intensity factor KIC in the R and L directions is measured by the compact
tension test using small several specimens. The shape and size of plastic zone in crack tip is
determined by numerical simulations based on von Hill yield criterion. The results show that
anisotropic material constants do not affect the length of plastic zone along crack direction and it only
operates on the plastic zone with θcr≠ 0. Strength ratios α1, α2 and toughness ratios r1, r2, influencing
on the plastic zone, are discussed. Comparative analysis shows that r1 and r2 work markedly on the
shape and size of plastic zone, whereas α1, α2 do less.
Increase of Stress Intensity near Free-Edge of Elastic-Creeping Bi-Material Interface under a Sustained Load
Authors: Ngampungpis Kittikorn , Hirakata Hiroyuki , Kitamura Takayuki
Published: March 2009

The transition from SSC to LSC ahead of a crack tip (notch root) or an ordinary interface edge
(bad pair) causes stress relaxation and the decrease of stress intensity in general. However, the good
pair bi-material and the bad pair bi-material with weak elastic stress singularity in this study show
the inverse phenomenon under the transition. The results indicate that the stress near the interface
edges of both cases, which have no or low stress singularity at the loading instant, increases and
brings about the stress concentration during the transition. In addition, the creep strain distribution
in the early stage is different from that occurred in the transition of an ordinary interface edge (bad
pair) or a crack tip (notch root).
Plasticity Characteristics of Beta Titanium Alloy Obtained Using Depth-Sensing Nano-Indentation Test
Authors: Wang Xiao Teng , Yoshida Fusahito , Fang Hong Yuan
Published: March 2009

In this study, depth sensing nano-indentation test was carried out to investigate the
plastic/viscoplastic behavior of beta titanium alloy. The indentation experiment results showed that
both hardening and softening effect existed in indentation process and the residual penetration depth
was deeper when the nominal indentation strain rate increased. That is opposite to the room
temperature tension test results, which showed a strain rate hardening behavior. FEM simulation
combined with viscoplastic model was carried out to simulate the indentation procedure. FEM
results showed that the pile-up pattern changed with the consideration of the nominal indentation
strain rate effect. Atom force microscope (AFM) observation gave a same result of pile-up patterns.
Formability Evaluation of Coated and Uncoated Steel Sheets with Consideration of Frictional Characteristics
Authors: Ko Dae Cheol , Lee Kyoung Su , Lee Jung Min , Kim Byung Min
Published: March 2009

Galvannealed steel sheets are being widely used in automotive application for better
corrosion resistance. It is generally known that uncoated steel sheets have better mechanical
properties than coated steel sheets due to presence of zinc coating. But frictional characteristics of
coated steel sheets are very different from those of uncoated steel sheets. Therefore the study on
mechanical and frictional characteristics of these steel sheets is needed. In this study, tensile test was
performed to evaluate mechanical properties of coated and uncoated steel sheets. Cup drawing test
was performed to measure friction-coefficient. And frictional characteristics were analyzed by using
FE-analysis. The effect of mechanical and frictional properties on cup drawing was investigated. It
was shown that the frictional properties more affected cup drawing.
The Effect of Heating Rate on the Formability of Bulk Metallic Glass in a Supercooled Liquid Region
Authors: Lee Kwang Seok , Bang Won Kyu , Ha Tae Kwon , Ahn Sang Ho , Chang Young Won
Published: March 2009

The formability of a Zr41.2Ti13.8Cu12.5Ni10Be22.5 bulk metallic glass has been investigated in the present study
in relation to the heating rate. A series of extrusion tests after rapid heating has been performed in a
laboratory scale together with sheet forming tests after slow heating for comparison purpose. The basic
processing map based on dynamic materials model (DMM) and compression test data has been utilized to
evaluate feasible forming conditions. The macroscopic formability, classified by fully formed, partially
formed or a catastrophic fracture, is found to have a good correspondence with the iso-efficiency contour in
the processing map. The region of high power dissipation efficiencies with η>0.8 is found to be broaden by
avoiding crystallization events due to reduced exposure time in extrusion process with a faster heating rate.
Adaptive Simulations of T-Shape Tube Hydroforming Processes
Authors: Hwang Yeong Maw , Chen Bing Hong , Chang Wen Chan
Published: March 2009

A successful THF process depends largely on the loading paths for controlling the
relationship between the internal pressure, axial feeding and the counter punch. In this study, an
adaptive algorithm combined with a finite element code LS-DYNA 3D is proposed to control the
simulation of T-shape hydroforming with a counter punch. The effects of the friction coefficients at
the interface between the tube and die on the loading path and thickness distribution of the formed
product are discussed. Experiments of protrusion hydroforming are also conducted. The final shape
and thickness distribution of the formed product are compared with the simulation results to verify the
validity of this modeling.
Numerical Simulation of Warm Deep Drawing of AZ31 Magnesium Alloy Sheet with Variable Blank Holder Force
Authors: Peng Ying Hong , Chang Qun Feng , Li Da Yong , Jie Hu , Zeng Xiao Qin
Published: March 2009

Blank holder force (BHF) plays an important role in sheet metal forming. Previous
studies demonstrated that variable blank holder forces can improve the cold formability of
steel blank, but the research on the application of variable blank holder force in warm forming
of magnesium sheet forming has not been well investigated. In this study, the mechanical
property of AZ31 magnesium alloy sheet is measured through some uniaxial tensile tests. In
order to obtain the variational rule of the BHF, a mathematical model of BHF is deduced
based on the energy theory. The variational rule of the BHF over the punch stroke is analyzed.
Finally, three profiles of the BHF curve are designed, and the numerical simulation of warm
deep drawing process of magnesium alloy sheet is also performed. A suitable variable blank
holder force scheme is obtained through comparison among three results of simulation. The
simulation indicates that the limiting drawing ratio of AZ31 magnesium alloy sheet can be
improved from 3.0 to 3.5 with the suitable blank holder force varied by an inverted V curve.
Investigation of the Dynamic Buckling in the Carbon Nanotube under Impact Torque
Authors: Sha Feng Huan , Zhao Long Mao , Yang Gui Tong
Published: March 2009

The dynamic buckling caused by propagation of a stress wave in single-wall carbon
nanotube subjected to impact torque is investigated. The single-wall carbon nanotube is modeled by a
cylindrical shell with semi-infinite length, and the dynamic buckling under impact torque is reduced
to a bifurcation problem caused by the propagation of torsion stress wave. The bifurcation problem
can be converted to solving a group of nonlinear algebraic equations. The numerical computation is
carried out, and the effects of the different parameters on dynamic buckling are discussed. It is found
that if critical buckling time of the carbon nanotube is different, the corresponding buckling model is
different, too. Relation between the critical buckling stress and the critical buckling time is given.
Molecular-dynamic simulations of torsional deformation of a single-wall carbon nanotube have been
used to obtain the critical buckling strain, which is 0.064. In this work, the critical buckling strain
obtained by the continuum model is 0.061, which is very close to the value 0.064. Single-wall carbon
nanotubes have very much powerful anti-impact torque, and the critical buckling shearing stress can
reach up to 132GPa.
Hot Forging Comparative Analyses by Using a Combined Finite Element Method
Authors: Guo Yong Ming
Published: March 2009

In this paper, single action die and double action die hot forging problems are analyzed by a
combined FEM, which consists of the volumetrically elastic and deviatorically rigid-plastic FEM and
the heat transfer FEM. The volumetrically elastic and deviatorically rigid-plastic FEM has some
merits in comparison with the conventional rigid-plastic FEMs. Differences of calculated results for
the two forging processes can be clearly seen in this paper. It is also verified that these calculated
results are similar to those of the conventional rigid-plastic FEM in comparison with analyses of the
same numerical examples by the penalty rigid-plastic FEM.
Effect of Tool Modeling Accuracy on Sheet Metal Forming Simulation
Authors: Hama Takayuki , Takamura Masato , Teodosiu Cristian , Makinouchi Akitake , Takuda Hirohiko
Published: March 2009

This paper describes the effect of tool modeling accuracy on the accuracy of springback
simulation in sheet metal forming. Simulations of a two-dimensional draw-bending process are
carried out by using the polyhedral tool model and the model whose surface is smoothed by
quadratic parametric surfaces proposed by Nagata [1]. It is found that the tool modeling, especially
the normal vector accuracy in the present model, plays an important role in the prediction not only
of deformation but also of stress distribution. The simulated results show that the tool model based
on the so-called Nagata patch enables a more accurate and efficient simulation.
Constitutive Modeling for Uniaxial Time-Dependent Ratcheting of SS304 Stainless Steel
Authors: Kang Guo Zheng , Kan Qian Hua , Zhang Juan , Liu Yu Jie
Published: March 2009

Based on the experimental results of uniaxial time-dependent ratcheting behavior of
SS304 stainless steel at room temperature and 973K, three kinds of time-dependent constitutive
models were employed to describe such time-dependent ratcheting by using the Ohno-Abdel-Karim
kinematic hardening rule, i.e., a unified viscoplastic model, a creep-plasticity superposition model
and a creep-viscoplasticity superposition model. The capabilities of such models to describe the
time-dependent ratcheting were discussed by comparing with the corresponding experimental
results. It is shown that the unified viscoplastic model cannot provide reasonable simulation to the
time-dependent ratcheting, especially to those with certain peak/valley stress hold and at 973K; the
proposed creep-plasticity superposition model is reasonable when the creep is a dominant factor of
the deformation, however, it cannot provide a reasonable description when the creep is weak; the
creep-viscoplastic superposition model is reasonable not only at room temperature but also at high
temperature.
The Influence of Cladding on the Springback of 2024-T3 Aluminium Alloy
Authors: McMurray Robert J. , Leacock Alan G. , Brown Desmond
Published: March 2009

Double curvature nacelle skin components are often produced in 2024-T3 Alclad
aluminium alloy (clad both sides), using simple stretch forming. For this process uniaxial-tension is
assumed to be the dominant mode of deformation. The observed springback in these components is
generally minimized by inducing high levels of strain within the forming limits of the material.
Experimental investigations to quantify the level of the springback have revealed an underlying
aspect of material behaviour, which to the authors’ knowledge, has not been reported elsewhere.
The results of this investigation have shown a remarkable dependence on specific material
parameters unique to the Alclad material. Whilst previous investigations [1, 2, 3] have shown the
influence of cladding, it has been assumed that cladding layers on both sides produce effects that are
symmetrical about the mid-plane of the sheet. However, the current investigation has revealed a
distinct asymmetry in springback behaviour. A detailed study of cladding thickness and strength,
residual stresses and through-thickness material property changes has revealed that this asymmetry
results from a complex combination of these parameters.
Implicit Stress Integration for High-Temperature Inelastic Constitutive Models Using Linearization
Authors: Akamatsu Masafumi , Nakane Kazuhiko , Ohno Nobutada
Published: March 2009

In this study, a linearization approach is used to develop an implicit integration scheme
for high-temperature inelastic constitutive models based on non-linear kinematic hardening. A
non-unified model is considered in which inelastic strain rate is divided into the transient and steady
parts driven, respectively, by effective stress and applied stress. By discretizing the constitutive
relations using the backward Euler method, and by linearizing the resulting discretized relations, a
tensor equation is derived to iteratively achieve the implicit integration of constitutive variables.
The integration scheme is then programmed as a subroutine in a finite element code and applied to a
lead-free solder joint analysis. It is thus demonstrated that the integration scheme affords the
quadratic convergence of iteration even for considerably large increments.
A New Method for Stress and Deformation Analysis from Nano to Macro Dimensional Scales
Authors: Gu Yuan Tong , Zhang Liang Chi
Published: March 2009

This paper presents a concurrent multiscale method for the stress analysis of solids using
a coupled meshless and molecular dynamic analysis. A new transition algorithm using transition
particles was employed to ensure the compatibility of both displacements and their gradients. The
equivalent continuum strain energy density was obtained locally based on the atomic potential and
Cauchy-Born rule, and hence plasticity can be easily handled in not only the atomic domain but also
the continuum domain. Numerical examples demonstrated that the present multiscale technique has
a promising potential of application to multiscale systems subjected to deformation.
Molecular Dynamics Analysis for Deformation and Fracture Behavior of Copper Thin Films
Authors: Fujii Tomoyuki , Akiniwa Yoshiaki
Published: March 2009

Molecular dynamics simulation is conducted to investigate the effect of notch depth on
the deformation and fracture behavior of a single crystal copper which is expected to a conductive
material of micro-devices. In the stress – strain relationship, a normal stress increases with
increasing applied strain. Then, the normal stress decreases rapidly. When the stress decreases, the
dislocation emits from a notch root and the stacking fault is formed on the {111} plane, which is
slip plane of the fcc crystalline structure. The maximum stress decreases with notch depth. The
non-damaging defect size is quite small. The shear stress in the slip direction at dislocation emission
is constant irrespective of the notch depth. The criterion of the dislocation emission is given by the
critical value of the resolved shear stress in the sliding direction.
Study on Silk I Porous 3-D Scaffolds
Authors: Lu Shen Zhou , Feng Lin , Li Ming Zhong , Di Chuan Xia , Bai Lun
Published: March 2009

A series of porous silk fibroin materials were prepared by freezing fibroin aqueous
solution at –18 °C for 10 days. The process required no freeze-drying, chemical cross-linking, or the
aid of other polymeric materials. X-ray powder diffraction patterns from the porous silk materials
displayed features of crystal of metastable silk I polymorph. By adjusting the preparation conditions,
silk I porous materials with average pore diameter of 30-240 μm and porosity of 70 -95 % can be
prepared. The silk I porous materials were embedded in hypodermis on the dorsal surface of SD
white rats, resulting that all rats survived with good general condition, and silk I porous materials
were degraded and absorbed mostly in 6 weeks.
The Effect of Diameter of Electronspun PGA Scaffold for Biological Behaviour of Human Umbilical Vein Endothelial Cells
Authors: Tian Furong , Hossinkhani Hossein , Yokoyama Yoshiro , Gomes Estrada Giovani , Kobayashi Hisatoshi
Published: March 2009

The objective of this work was to investigate cell adhesion, Poly Glycolic Acid (PGA)
and PGA/ collagen nano-fibers on the silicone membrane. PGA with the weight-mixing ration of
40% was fabricated through the electronspun technique. The behaviors of Human Umbilical Vein
Endothelial cells on these scaffolds are evaluated. The highest cell adhesion was observed in the
PGA/collagen fibers with the diameter of 500 nm. This study indicates the effect of nano-fibers on
the Human Umbilical Vein Endothelial cells for better understanding of interactions of cells with
scaffold materials. Such information will have important implications for implantable vascular
tissue engineering constructs.
A Novel Polycaprolactone/Hydroxyapatite Scaffold for Bone Tissue Engineering
Authors: Song Ho Hyun , Yoo Mi Kyong , Moon Hyun Seuk , Choi Yun Jaie , Lee Hyun Chul , Cho Chong Su
Published: March 2009

In this study, novel polycaprolactone/hydroxyapatite (PCL/HA) scaffolds were prepared to
increase mechanical properties and degradation of PCL/HA ones for bone tissue engineering. PCL
macromers were synthesized through the reaction of PCL diol (Mn: 530, 1250, and 2000) and PCL triol (Mn:
900) with acryloyl chloride and confirmed using nuclear magnetic resonance spectrometer (NMR) and
fourier transform infrared (FTIR). The PCL/HA scaffolds were prepared by cross-linking of PCL macromer
in the presence of HA by UV treatment and freeze drying methods. Mechanical property and porosity as well
as degradability of the PCL/HA scaffolds were also investigated. PCL/HA scaffolds showed faster
degradation and higher compressive modulus than those of PCL itself due to their low crystallinity and
modification of terminal groups. The pore morphology and pore sizes of the PCL/HA scaffold were checked
by scanning electron microscope (SEM). Cell cytotoxicity and proliferation of MG-63 osteoblast cultured
onto the PCL/HA scaffold was assessed by lactate dehydrogenase (LDH) assay and Alamar blue assay,
respectively. The novel PCL/HA scaffold appears to be suitable for bone substitutes.
Thermosensitive and Cell-Adhesive Pluronic Hydrogels for Human Adipose-Derived Stem Cells
Authors: Park Kwi Deok , Jung Hong Hee , Son Jun Sik , Rhie Jong Won , Park Ki Dong , Ahn Kwang Duk , Han Dong Keun
Published: March 2009

Pluronic F127 has received increasing attention over many years as drug delivery
systems, biomaterials, and hydrogels for tissue engineering. In this study, we synthesized
temperature-sensitive and cell-adhesive triblock F127 copolymers, in which Arg-Gly-Asp (RGD)
peptide ligand was grafted to Pluronic F127-4-methacryloxyethyl trimellitic anhydride (4-META)
to obtain F127-META-RGD. The chemical structures of the F127-META-RGD block copolymers
were confirmed by FTIR, 1H and 13C NMR, and GPC. The resultant F127-META-RGD showed
very similar thermosensitive behaviors to F127 and F127-META. The critical micelle temperature
(CMT) of the F127 copolymers decreased in the order of F127 < F127-META <
F127-META-RGD, whereas the particle size followed an opposite trend. Interactions between the
F127 copolymers and adipose-derived stem cells (ASC) were evaluated in terms of cell adhesion
and proliferation on the hydrogel. These thermosensitive RGD-grafted Pluronic hydrogels that
display the enhanced cell adhesiveness, are expected to be useful as a functional injectable scaffold
for tissue engineering.
A Poly(β-Amino Ester) of Spermine and Poly(ethylene Glycol) Diacrylate as a Gene Carrier
Authors: Jere Dhananjay , Kim Tae Hee , Arote Rohidas B. , Jiang Hu Lin , Cho Myung Haing , Nah Jae Woon , Cho Chong Su
Published: March 2009

Vectors are vital aspect of gene delivery system which decides the success of gene
therapy. Efficient transfection with minimum or no toxicity, are two principal aims of any gene
delivery system. In this our study, we rationally developed biodegradable water soluble poly(ßamino
ester) (PAE) based on spermine (SPR) and poly (ethylene glycol) (PEG), by Michael-type
addition reaction and further studied for its potential as a gene carrier. Confirmation of synthesized
PAE was done by proton NMR spectroscopy. In gel retardation assay, the PAEs have shown good
DNA binding ability over wide range of polyplexes. The addition of PEG over SPR resulted in a
novel PAE with higher degree of safety and transfection efficiency as compared with
polyethylenimine 25K (PEI) when studied in 293T human kidney carcinoma cells.
Study of Biodegradation of Pure Magnesium
Authors: Ren Yi Bin , Wang Hao , Huang Jing Jing , Zhang Bing Chun , Yang Ke
Published: March 2009

Magnesium and its alloys are possible to develop new type of biodegradable medical
magnesium alloys by using their active corrosion potential. The bio-corrosion properties of the high
pure magnesium in the Hank’s solution were investigated in this paper, the results showed that high
pure magnesium had a low corrosion rate and hydrogen release in Hank’s solution, when the pH value
of solution was controlled at 7.5, the corrosion rate was under 0.2mm/year, the production of hydrogen
was about 0.15ml/cm2, and if the solution wasn’t controlled on pH value, the corrosion rate was about
0.02 mm/year, production of hydrogen was about 0.1ml/cm2 . Result of in vitro Kinetic clotting time
test and animal implant prep-test showed that High pure magnesium had good thromboresistant
property and tissue compatibility, pure magnesium can biodegrade lowly in animal body and formed
surface apatite, which proportion of Ca/P was similar with bone tissue.
Hydrogen Peroxide Sensor Based on Horseradish Peroxide (HRP) Immobilized PANI Electrode with Au Nanoparticles
Authors: Seo Kang Deuk , Oh Seong Dae , Choi Seong Ho , Oh Sang Hyub , Woo Jin Chun , Park Hae Jun
Published: March 2009

In order to prepare the enzyme electrode for sensing of chemical molecules, the Au was
coated on the surface of PP film by sputter coater. Polyaniline (PANI) was polymerized on the
surface of the coated Au film by electrochemical polymerization of aniline in order to use working
electrode. Subsequently, horseradish peroxide (HRP) was immobilized on PANI electrode as
follows: Method I. The HRP was immobilized on the surface of PANI electrode by using Au
nanoparticle as linker (physical adsorption). Method II. The HRP was immobilized on the surface of
PANI electrode by using 2-aminothiophenol and Au nanoparticle as linker (Self-assembling
immobilization). Method III. HRP was directly immobilized with PANI electrode by using glutaric
dialdehyde as linker (covalent bonding). The sensing efficiency of the prepared HRP-PANI
electrode was also examined. The sensing efficiency of the HRP-PANI electrode for H2O2 was as
following order; Method I > Method III > Method II..
Influence of Pre-Forming on the Forming Limit Diagram of Aluminum and Steel Sheets
Authors: Tolazzi Massimo , Merklein Marion
Published: March 2009

This paper presents a method for the experimental determination of forming limit
diagrams under non linear strain paths. The method consists in pre-forming the sheets under two
different strain conditions: uniaxial and biaxial, and then stretching the samples, cut out of the
preformed sheets, using a Nakajima testing setup. The optical deformation measurement system
used for the process analysis (ARAMIS, Company GOM) allows to record and to analyze the strain
distribution very precisely with respect to both time and space. As a reference also the FLDs of the
investigated grades (the deep drawing steel DC04, the dual phase steel DP450 and the aluminum
alloy AA5754) in as-received conditions were determined. The results show as expected an
influence of the pre-forming conditions on the forming limit of the materials, with an increased
formability in the case of biaxial stretching after uniaxial pre-forming and a reduced formability for
uniaxial load after biaxial stretching if compared to the case of linear strain paths. These effects can
be observed for all the investigated materials and can be also described in terms of a shifting of the
FLD, which is related to the art and magnitude of the pre-deformation.
Material Superplastic Parameters Evaluation by a Jump Pressure Blow Forming Test
Authors: Sorgente Donato , Palumbo G. , Tricarico Luigi
Published: March 2009

In this work a method, based on bulge tests performed on a blow forming equipment, for
evaluating the superplastic material characteristics is proposed. The pressure imposed on the sheet
and the height of the dome of the specimen during the test are used as characterizing parameters.
Different pressure levels are applied subsequently in the same test and the strain rate sensitivity
index is calculated starting with analytical considerations and then with an inverse approach based
on a simple finite element numerical model of the test. The change of the slope in the specimen
dome height curve, due to the change of the pressure, is correlated to the strain rate in the sheet. The
method has been verified applying other load profiles on the sheet and good agreement has been
found between experiments and numerical results obtained by the inverse analysis.
A Comparative Method of Analysis for Evaluating Sheet Metal Machine Tool Flexibility
Authors: Marobin Mario
Published: March 2009

In the machine tool sector, for production purposes, flexibility and automation are elements that
play conflicting roles because greater automation generally means less flexible production. As a
result, it is not easy to choose between technologies that have different degrees of automation or
may even be manual. We are therefore proposing a comparative method of analysis that can be used
to evaluate one machine tool with respect to another, which is used as a reference. This combination
leads to the identification of breakeven points on productivity, flexibility and automation that, when
taken together, provide criteria for evaluating the economic suitability or unsuitability of the choice
in hand. This comparative model rotates around evaluation variables that have long been
consolidated and recognized by sheet metal machine tool manufacturers and users.
Dimensional Deviation of Roll Formed Components Made of High Strength Steel
Authors: Groche Peter , Henkelmann Michael
Published: March 2009

During the last half century roll forming has become a highly productive metal forming
technology, well-established in the industry for the manufacturing of mass products. About
8 % of the annual world production of steel is processed by roll forming mills. Roll forming
technology enables the manufacturing of profile-shaped products with an extremely wide spectrum
of geometrical shapes. In lightweight construction, the utilization of roll-formed structures of high
and ultra-high-strength steels has increased remarkably in the recent years. However, the application
of those types of steel entails some disadvantages resulting in a decreasing forming capacity and
enormous efforts to reach the required dimensional accuracy. Until a profile leaves the roll forming
machine with the target quality, it is mostly necessary to align the forming rolls several times.
Sometimes even design changes are required. This is the result of unreliable process planning.
Furthermore, typical profile failures such as twist, flare and spring-back occur even stronger
compared to mild steels. Nowadays, it is usual to control the dimensional accuracy of the profiles
after the last forming stand. This kind of quality control has the following disadvantage:
manufacturing errors are detected very late. Therefore, a continuous quality control process and an
active manipulation during the forming process promise a large potential for an improvement of the
dimensional accuracy and an increase of roll forming productivity.
Geometry-Flexible Production – a Production Engineering Challenge
Authors: Neugebauer Reimund , Kunke Eberhard , Bräunlich Hans , Göschel Angela
Published: March 2009

Today's automotive manufacturers are required to meet ever greater demands for
increased flexibility due to decreasing batch sizes. Solutions to meet these demands will bring about
far-reaching changes to the mass productions methods which currently dominate automotive
manufacturing. In addition to the current need for sheet metal components, such trends will also
have an effect on assembly and joining techniques used. The paper describes the challenge for
production engineering resulting from current and future market demands.
Hot Stamping and Press Quenching of Ultrahigh Strength Steel Sheet Using Resistance Heating
Authors: Maki Seijiro , Hamamoto Atsushi , Saito Shouichi , Mori Kenichiro
Published: March 2009

The feasibility of hot stamping and press quenching of ultrahigh strength steel sheet
using resistance heating was investigated by demonstrating experiments. In the experiments, a
rectangular blank of high strength steel sheet, SPFC980Y, 1.2mm thick, 20mm wide and 130mm
long was used and it was resistance-heated with a pair of parallel electrodes placed 120mm away
from each other, using an AC power supply with a function of input energy control. The relationship
between input energy and heating temperature was examined and then hot stamping and press
quenching performances were examined. The press quenching was also experimented in hot
hat-shaped bending, and the influences of the heating temperature on spring-back and hardness
property were investigated. The results of the experiments revealed that hot stamping and press
quenching using resistance heating are highly feasible.
Optimisation of the Stamping Parameters of a Drawn-Part Made of Stainless Steel
Authors: Lacki Piotr
Published: March 2009

Demand for an increase in the useable properties of a drawn-part made of stainless steel
has been the inspiration for the work. The use of 4H13 steel instead of 3H13 has resulted in the
higher strength of the drawn-part but also a decrease in drawability. Therefore, some modifications
to the original design of the sheet-metal forming process were necessary. A numerical simulation
was applied to optimise of the stamping process. The ADINA System based on the finite element
method (MES) was used. Frictional conditions on the contact surfaces, blank diameter and the
course of the blank holding force versus time were analysed. In this paper, the test results of the
mechanical properties of the analysed sheets (3H13 and 4H13 stainless steel) are given, some
differences in the way of stamping drawn-parts made of these materials are discussed and the results
of the numerical simulation are presented. A 3D model and perfectly rigid tool were assumed in the
numerical model. The sheet was modelled using shell elements. The elastic and plastic properties of
the sheet material were assumed and the frictional conditions on the contact surfaces were taken into
consideration during the numerical simulation. Based on the numerical simulation the stamping
process was optimised. A comparison between the numerical calculation and test results shows
good convergence. Thanks to the MES analysis and the application of the new technological
parameters, the desired drawn-part with the better useable properties was obtained.
Detailed Incremental Forming of Steel Beverage Cans by a High-Pressure Water Jet
Authors: Emmens Wilko C.
Published: March 2009

This paper describes the process of shaping fully formed beer & beverage cans with a
rotating high-pressure water jet. In detail the paper discusses situations where forming is restricted
to a limited area by using a special mould. This causes the strain to shift to biaxial causing quite
different properties. The process is compared to ‘normal’ incremental forming showing many
similarities that are discussed in more general terms and can be summarized into four propositions.
A New Incremental Sheet Forming Process Based on a Flexible Supporting Die System
Authors: Maidagan E. , Zettler Joachim , Bambach Markus , Rodríguez P.P. , Hirt Gerhard
Published: March 2009

Nowadays many industrial sectors use forming processes in order to produce sheet metal
components. The most widely used processes are stamping and deep drawing, which are based on
big, costly dies and presses. These processes require large initial investment and specific dies for
each part, which makes them inflexible and only profitable for large batches. A possible approach
to small series production is based on the incremental sheet forming technique (ISF), which consists
of a gradual plastic deformation of flat sheet metal by the action of a CNC controlled tool.
Equipment such as a 3-axis milling machine can be used for ISF, such that the initial investment
costs in ISF are around 5-10% of those required to set up a production line for conventional
stamping. In its current stage of development, dedicated dies are often used as support tools in ISF.
However, due to the fact that the forming forces are low in ISF, the dies can be made out of cheap
materials like resin or wood. Although this is an additional advantage over stamping, the need to
use additional tools still reduces the flexibility of the process.
The present paper details the concept of a truly “dieless” incremental forming process. In the
framework of the SCULPTOR EU project, the authors are working on an innovative concept of
incremental sheet metal forming which is based on the replacement of the commonly used dies by a
second forming tool which moves in a coordinated way with the first forming tool, thus creating a
flexible die system, which does not depend on the specific geometry of the part to be formed.
The present work summarizes the results obtained up to now in two fields: (i) the development
of a prototype for the flexible die system to be included both in milling machines or combined with
robots and (ii) process modelling to improve the understanding of the process.
Dieless Clinching and Dieless Rivet-Clinching of Magnesium
Authors: Neugebauer Reimund , Dietrich Stephan , Kraus Christian
Published: March 2009

Joining by forming of magnesium alloys is restricted by the limited forming capability of
magnesium at room temperature. For this reason heating of the parts to temperatures of 220 °C or
more is required to form connections without cracks. State-of-the-art joining by forming methods
(such as clinching or self-pierce riveting) are usually working with a contoured die as a counter tool.
Researches on these joining methods have shown that a minimum heating time of 3 to 6 seconds is
needed to achieve connections of acceptable quality. New joining by forming methods working with
a flat anvil as counter tool make it possible to decrease the heating time considerably. In this paper
two methods – the dieless clinching and the dieless rivet-clinching – and their potential for the
joining of magnesium parts shall be introduced in detail. The results of extensive research on the
influence between heating parameters and the formation of the connections as well as the results of
tensile test done to characterize the strength of dieless joined connections are discussed.
Numerical Prediction of the Shape of the Molten Pool in a Stationary TIG Welding Process
Authors: Bini Riccardo , Monno Michele
Published: March 2009

A numerical model of the electric arc is coupled to a model for the convective flow in the
molten pool of a stainless steel sheet during a stationary TIG welding process. This approach allows
us to predict the shape of the bead, which is determined by the balance between the Marangoni
forces on the free surface and the radial drag from the arc jet impingement.
The surface tension of the molten steel is greatly influenced by its temperature and sulphur
content, as experiments showed very different bead shapes associated to the same welding
parameters. We simulate three sulphur contents, namely 10 ppm, 40 ppm and 100 ppm, showing
their effects on the velocity and temperature distributions in the molten pool. A transition between
drag-dominated and surface tension-dominated pools is found at a sulphur content of few dozens, in
agreement with previous experimental observations.
Experimental Analysis of AA5083 Butt Joints Welded by CO2 Laser
Authors: Tricarico Luigi , Spina Regula , Sorgente Donato , Ancona A. , Sibillano T. , Basile G.
Published: March 2009

Laser butt-welding of AA5083 has been investigated using a high quality CO2 laser in
continuous wave regime. The effect of laser power, welding speed and specimen thickness on
mechanical properties of the welded joints were evaluated by employing a general full factorial
experimental plan design. The experimental results indicate important suggestion to choose proper
combinations of process parameters and achieve high strength butt welded joints.