bluuebunny/crossref_metadata_2025 huggingface dataset:
Phase-Field Modeling of Morphological Change of Ferrite during Decomposition of Austenite in Fe-C Alloy
Authors: Yamanaka A. , Takaki Tomohiro , Tomita Yoshihiro
Published: March 2009

The integrated simulation model for microstructural design of Fe-C alloy using the
phase-field method and the homogenization method is proposed. First, the phase-field simulation is
performed to simulate the morphological change of the grain boundary ferrite to Widmanstätten
ferrite. Then, in order to clarify the effects of the morphology of the ferrite phase on the micro- and
macroscopic mechanical properties, the finite element analysis based on the homogenization method
is conducted with the representative volume element obtained from the phase-field simulation. This
numerical approach provides a powerful tool to investigate systematically the micro and macroscopic
mechanical behavior with the morphological change of the ferrite phase in the Fe-C alloy.
First-Principles Study on Elastic Anomalies in Ag/Al Multilayers
Authors: Kinoshita Yusuke , Umeno Yoshitaka , Kitamura Takayuki
Published: March 2009

Using the first-principles calculation, the elastic constant C44 of Ag/Al multilayers with
different modulation periods from 0.43 nm to 2.27 nm has been evaluated in order to examine the
effect of atomic and electronic structures on it. With increasing modulation period, C44 decreases
and becomes close to that obtained by the conventional mixing rule, however, the difference of 8 %
still remains at the modulation period of 2.27 nm. As C44 correlates with the average interplanar
spacing, the decrease of C44 can be explained by the decrease of the charge density in the stacking
direction due to the increase of the average interplanar spacing. The difference in the electronic
structure is included in the effect of atomic structure.
Structural Transformation of Single Crystal Silicon under Uniaxial Stress
Authors: Jeong Seong Min , Kitamura Takayuki
Published: March 2009

The diamond structure of single crystal silicon transforms to other structures under
mechanical stress. We investigate the structural transformation of diamond cubic structure to betatin
structure in silicon under uniaxial stress using atomistic simulation on the basis of the Tersoff
potential. As a result, under extensive compressive strain, the structural transformation from Si-I to
Si-II is found.
Experimental and Theoretical Investigation of Viscoplastic Deformation of Solder Alloys for Electronic Packaging
Authors: Kobayashi Takuji , Sasakir Katsuhiko , Ohguchi Ken-Ichi , Narita Yoshihiro
Published: March 2009

This paper discusses ratchetting deformation of lead-free solder Sn/3Ag/0.5Cu and
lead-containing solder alloy Sn/37Pb with several stress amplitudes and stress ratios of the maximum
stress to the minimum stress. First the uniaxial ratchetting testsare conducted with three maximum
stresses and five stress ratios. The all tests are conducted using cylindrical bulk specimens of the
solder alloys at 313 K. The test results show that there is the difference in the viscoplastic deformation
behavior between two solder alloys. The relationship between ratchetting strain and time is estimated
by Biley-Norton law to explain that the uniaxial ratchetting deformation is strongly dominated by the
viscous deformation. Finally, the ratchetting deformation is simulated by the dislocation based
constitutive model proposed by Estrin [1]. The simulations show that there is a possibility to simulate
the uniaxial ratchetting by clarifying the dislocation mechanism of the solder alloys.
High Temperature Low Cycle Fatigue of Superalloys Inconel 713LC and Inconel 792-5A
Authors: Petrenec Martin , Obrtlík Karel , Polák Jaroslav
Published: March 2009

Cylindrical specimens of cast polycrystalline nickel base superalloy Inconel 713 LC and
Inconel 792-5A were cyclically strained under total strain control at 23 and 700 °C. Morphology and
volume fraction of γ´ precipitates are different in both materials. Cyclic hardening/softening curves,
cyclic stress-strain curves, and fatigue life curves were obtained at both temperatures. The cyclic
hardening/softening curves depend both on temperature and plastic strain amplitude. The cyclic stressstrain
curves can be fitted by power law. Experimental data of fatigue life curves can be approximated
by the Manson-Coffin and Basquin laws. Dislocation structure was studied in transmission electron
microscope. Planar dislocation arrangements in the form of bands parallel to {111} planes were
identified in both superalloys at both temperatures. Stress-strain response and fatigue life characteristics
are compared at both temperatures and discussed in relation to dislocation arrangement and structural
parameters of the materials studied.
Growth of Short Fatigue Cracks Emanating from Notches in an Austenitic-Ferritic Stainless Steel
Authors: Kotecký Ondřej , Degallaix Suzanne , Polák Jaroslav
Published: March 2009

The present work studies the effect of the microstructure and of the stress gradient on the
early fatigue crack growth in a two-phase austenitic-ferritic stainless steel. Fatigue tests were
performed on two geometries of double edge notched specimens. Direct optical observations of the
surface are used to measure the surface crack growth rates. The results are presented and the effects
of stress and strain gradients on the crack propagation kinetics are discussed.
Aspects of the Modeling of High-Cycle Fatigue
Authors: Paluszyński Błażej , Böhlke Thomas
Published: March 2009

An overview on modeling of high-cycle fatigue is given and experimental findings of the
damage accumulation are discussed. Finally we sketch an isotropic constitutive model for the
description of the damage accumulation due to high-cycle fatigue.
Effects of Conductive Fillers on the Dynamic Response and Fatigue life of Conductive Asphalt Concrete
Authors: Wu Shao Peng , Li Bo , Qiu Jian , Li Ning
Published: March 2009

It is currently interesting to use thermal or electrical conductive asphalt concrete
for snow-melting and maintenance of asphalt pavements in winter. The addition of conductive
fillers may have negative effects on the mechanical properties of asphalt concrete. The
performance of conductive asphalt concrete is greatly affected by the initial crack and its
propagation. Laboratory tests for neat and conductive asphalt concrete include Dynamic
Modulus Test (DMT) and Indirect Tensile Fatigue Test (ITFT). DMT tests indicates that the
value of dynamic modulus of asphalt concrete decreases with the increasing graphite content.
It means that the conductive asphalt concrete achieves lower stiffness. It can be concluded
from ITFT tests that the fatigue life (load cycle times) of conductive asphalt concrete is more
than neat ones when stress level is under 1.0 MPa. Meanwhile higher fatigue resistance of
conductive asphalt concrete is observed when carbon fibers (2 weight % of total aggregate)
were added together with 22% graphite, especially at low stress levels.
Time-Variant Reliability Analysis of Ship Structure Subjected to Fatigue and Corrosion
Authors: Wang Shan , Shi Xing Hua , He Jian
Published: March 2009

Based on the characteristics of loading condition of ship structure in service and the
degeneration of the strength under fatigue and corrosion, the random time-variant model of ship
hull section modulus was set up using the theory of random process. Then the time-variant
reliability was analyzed with the method of up-crossing analysis and parallel system reliability. This
method could not only present successive decrease of reliability of the ship structure under fatigue
and corrosion, but also avoid the complicated numerical integration. It could be seen that this
method was easy to achieve. Furthermore, the time-variant reliability was compared with the annual
instantaneous reliability through an example, which indicated that this method was more precise,
and could provide some references to the decision-making of the reliability, maintenance and
safeguard.
Experimental Study on Fracture Properties of Cementitious Materials
Authors: Zhu Yu , Xu Shi Lang
Published: March 2009

For micro-fiber reinforced strain-hardening cementitious materials, in addition to the
basic characteristics and mechanical properties of fiber and interfacial properties between fiber and
matrix, mechanical properties of matrix such as strength and crack resistance are essential
parameters for material design, too. Therefore, the fracture properties of cement paste and mortar
which are two most basal cementitious materials were studied, using three-point bending beams of
which strength and depth are varied. Complete load versus crack mouth opening displacement
(P-CMOD) curve directly obtained, and double-K fracture parameters ini
Ic K and un
Ic K were
subsequently determined. The initial cracking load Pini was determined using resistant strain gauges.
The results show that an apparent stable crack propagation before unstable failure was observed
both in cement paste and in mortar. For cement paste, due to the influence of shrinkage crack, the
divergence of the unstable fracture toughness un
Ic K is more evident than initial fracture
toughness ini
Ic K .
Comparison of Computational Crack Path Predictions with Experimental Findings for a Quarter-Circular Surface Crack in a Shaft under Torsion
Authors: Buchholz Friedrich G. , Wiebesiek J. , Fulland M. , Richard Hans A.
Published: March 2009

In this paper the rather complex 3D fatigue crack growth behaviour in a shaft with a
quarter-circular crack under torsion is investigated by the aid of the programme ADAPCRACK3D
and by application of a recently developed 3D fracture criterion. It will be shown that the
computationally simulated results of fatigue crack growth in the FE-model of the shaft are in good
agreement with experimental findings for the development of two anti-symmetric cracks, which
originate from the two crack front corner points, that is where the crack front intersects the free
surface of the cylindrical laboratory test-specimens. Consequently, also for this case with a rather
complex 3D crack growth of two anti-symmetric cracks, the functionality of the ADAPCRACK3Dprogramme
and the validity of the proposed 3D fracture criterion can be stated.
Gearbox Failure Detection Using Growing Hierarchical Self-Organizing Map
Authors: Liao Guang Lan , Shi Tie Lin , Tang Zi Rong
Published: March 2009

Machine fault diagnosis is essentially an issue of pattern recognition, which heavily
depends on suitable unsupervised learning method. The Self-Organizing Map (SOM), a popular
unsupervised neural network, has been used for failure detection but with two limitations: needing
predefined static architecture and lacking ability for the representation of hierarchical relations in
the data. This paper presents a novel study on failure detection of gearbox using the Growing
Hierarchical Self-Organizing Map (GHSOM), an artificial neural network model with hierarchical
architecture composed of independent growing SOMs. The GHSOM can adapt its architecture
during unsupervised training process and provide a global orientation in the individual layers of the
hierarchy; hence the original data structure can be described correctly for machine faults diagnosis.
Gearbox vibration signals measured under different operating conditions are analyzed using the
proposed technique. The results prove that the hierarchical relations in the gearbox failure data can
be intuitively represented, and inherent structure can be unfolded. Then gearbox operating
conditions including normal, tooth cracked and tooth broken are classified and recognized clearly.
The study confirms that GHSOM is very useful and effective for pattern recognition in mechanical
fault diagnosis, and provides a good potential for application in practice.
Research on Fracture Damage Coupled with Crack Arrest by Anchorage Model of Discontinuous Jointed Rock Mass under the State of Complex Stress
Authors: Zhang Le Wen , Li Shu Cai , Wang Ying
Published: March 2009

Based on the hypothesis of equivalent strain energy and the theories of fracture
mechanics and damage mechanics，the constitutive model and fracture damage mechanism of
bolted discontinuous jointed rockmass are systematically studied under the state of complex stresses.
Initially ， considering the equivalent strain energy ， the constitutive relation of anchored
discontinuous jointed rockmass is derived under the state of compression-shear stresses. The
constitutive relation under the state of tension-shear stresses is also developed according to the theory
of self-consistence. Next，the damage evolution equations of discontinuous multi-crack rockmass
under compression-shear and tension-shear are put forward according to the wing crack-initiating
criterion. Finally，based on the above constitutive models and the damage evolution equations
three-dimensional finite element procedures have been developed to evaluate the stability and
deformability of the surrounding rock mass during excavation and supporting. The calculated results
indicate that above-mentioned constitutive relation and the damage evolution equations are available.
Microstructure Based Formability Characterization of Multi Phase Steels Using Damage Mechanics
Authors: Uthaisangsuk Vitoon , Prahl Ulrich , Bleck Wolfgang
Published: March 2009

Due to the coexistence of different micro structural components and their interactions,
multiphase steels offer an excellent combination between high formability and strength. On the
micro-scale, the fracture examination shows large influence of different phases and their
distributions on the mechanical properties and failure mechanisms. Considering the influence of
multiphase microstructure, an approach is presented using representative volume elements (RVE) in
combination with continuum damage mechanics (CDM). Herein, the influence of the material
properties of individual phases and the local states of stress on the material formability as well as
the failure behavior can be examined. By means of the RVE-CDM approach, a precise criterion for
the deformability characterization in sheet metal forming of multi phase steels is presented.
Identification of Damaged Bars in Three-Dimensional Redundant Truss Structures by Means of Genetic Algorithms
Authors: Viola Erasmo , Bocchini Paolo
Published: March 2009

The topic of this paper lies in the field of non-destructive parametric identification. Its
objective is to evaluate the mechanical characteristics of constituent bars in existing truss structures.
In particular, it locates bars with reduced mechanical properties and quantifies the loss of stiffness.
The suggested algorithm takes into account plane and three-dimensional structures, both statically
determinate and indeterminate. In the case where it is possible to measure strains only on some bars,
the procedure uses Genetic Algorithms to overcome the lack of information.
Damage Behavior of Metallic Materials under Very High Cycle Fatigue
Authors: Chai Guo Cai
Published: March 2009

The fatigue damage behavior of three two-phase steels in the very high cycle fatigue
regime (VHCF >108cycles) has been studied by both fatigue testing and microstructural
investigation using SEM and TEM. The results show that the S-N curves can vary from a single to
multi S-N curves, and there is also a transition of fatigue crack initiation from surface defect,
subsurface defect such as inclusion to subsurface non defect area or matrix depending on the steel
grades and its conditions. The surface crack initiation is caused by formation of irreversible slip
bands at the free surface or around surface defect. Subsurface inclusion crack initiation is mainly
caused by strain localization (slip bands) emanating at subsurface inclusion. Crack initiation in the
subsurface non defect area occurs in the areas that are physically weak. It is also a fatigue damage
process caused by micro cyclic plastic deformation. Formation of subsurface non defect fatigue
crack origin is a crack initiation and propagation process.
A Numerical Investigation about the Effects of the Riveting Operation on the Strength of Joints
Authors: Soprano Alessandro , Caputo Francesco , Grimaldi Alfonso
Published: March 2009

A new interest has been increasingly directed in recent years to study the behaviour of
joints provided with various kinds of fasteners and the mechanism of load transfer; profiting of the
present capabilities of computing systems and analysis codes, which appear such as to deal with
models built with more than one million elements, thanks to new numerical techniques which can
solve huge systems of equations. However, the main interest has been limited to the case of bolted
joints, for which several models are now available, while a few results are known for the case of
riveted joints, where more complex mechanisms are involved. In the present paper a full set of
analyses has been reported, with reference to both normal and blind rivets, where the manufacturing
operation has been simulated through Ls-Dyna to evaluate the stress and strain states induced into
the jointed sheets, varying the dimensional and riveting load characteristics of the joint. A
subsequent investigation is presented, which aims to evaluate the effects of the compressed zone
over the behaviour of an approaching crack.
A New Approach for Critical Chloride Content in (Non)Carbonated Concrete
Authors: Yoon In Seok , Koenders Eddy A.B.
Published: March 2009

The purpose of this study is to establish an analytical formulation for determination of the
critical chloride content in concrete. In this study, factors affecting the critical chloride content such as
mix proportion, environment, chemical evolution of pore solution with time, carbonation and so on
are taken into account. The numerical simulation program of cementitious materials, HYMOSTRUC
was utilized for the construction of the formulation. This was expressed as a free chloride content in a
mass unit of concrete as a time function.
On the Study of Fatigue Crack Propagation in the Time Domain
Authors: Zhang Jia Zhen , He Xiao Dong , Du Shan Yi
Published: March 2009

In-situ SEM observations have revealed that fatigue crack propagation in aluminium
alloys is caused by the shear band decohesion around the crack tip and the formation and cracking
of the shear band is mainly caused by the plasticity generated in the loading part of the load cycle.
This shear band decohesion process has been observed to occur in a continuous way over the time
period during the load cycle. Based on this observation, in this study, the transient fatigue crack
growth rate, da/dt, has been used to obtain the relationship between the conventional used parameter
da/dN and the applied driving force. It is proven that two parameters are necessary in order to
accurately describe fatigue crack propagation rate per stress cycle, da/dN. The well known stress
ratio effects on fatigue crack propagation rate can be correlated by this model.
Characterization of Early Fatigue Damage in Welded Structures by Thermal Imaging
Authors: Medgenberg Justus , Ummenhofer Thomas
Published: March 2009

The paper presents background information and experimental results regarding the
assessment of fatigue damage in welded steel structures by thermographic investigations of
thermomechanical coupling effects. The results confirm the high potential of specialized
thermographic methods for the experimental characterization of all stages of fatigue damage in
welded and un-welded components. The technique provides a new experimental mean to investigate
early inhomogeneous fatigue damage as mesoplasticity and cracks in the weld toe. The method has
been successfully applied during fatigue testing of welded components and allows detecting
localized damage as early as 10% to 20% of the total fatigue lifetime of the tested specimens.
Fatigue Behaviour of Notched PVD-Coated Titanium Components
Authors: Baragetti Sergio , Lusvarghi Luca , Pighetti Mantini F. , Tordini Federico
Published: March 2009

In this paper the fatigue behaviour of Ti-6Al-4V alloy coated with a TiN arc-deposited
PVD film was studied. Rotating bending tests (R = -1) were carried out on standard “hourglass”
specimens to evaluate the fatigue limit at 200000 load cycles. Conventional and notched (120° Vnotch
transversal to the rotating axis at the minimum cross section area) specimens were tested, both
coated and uncoated, to investigate the effect of the coating on the fatigue limit of the titanium
alloy, with and without the surface notch. Fracture surfaces were observed by SEM. The coating did
not improve the titanium alloy fatigue life.
Cyclic Damage Evolution in a PMC Laminate
Authors: Plumtree Alan , Melo M.
Published: March 2009

Using damage mechanics, cyclic damage evolution has been described and evaluated
in a non-crimped glass epoxy fabric composite. A fundamental fatigue study has been carried
out by progressively monitoring the fatigue damage modulus and crack density throughout the
life of an [0,+45,90,-45]2 (antisymmetric) laminate cycled at a stress ratio R (minimum
stress/maximum stress) of 0.1. Development of damage can be separated into two main stages.
Initially, damage increases very quickly during the first 10% of life (Stage I). Afterwhich, it
increases more slowly at a relatively constant rate to failure (Stage II). The changes in the
fatigue modulus and crack density both show the same behaviour. A large amount of damage in
the form of transverse matrix cracks develops during the first cycle. These then remain constant
throughout life. By contrast, the number of shear matrix cracks increase continually. The crack
density is cycle, not stress dependent. This behaviour is reflected by changes in the fatigue
modulus. Using damage mechanics, a representative equation has been applied to express the
progressive evolution of damage. The significance of which is that the amount of fatigue
damage at the end of Stage I for any stress level can be used to predict fatigue life and the
stress-life diagram for the laminate.
Interaction Effects due to Overloads and Underloads on Fatigue Crack Growth
Authors: Romeiro F. , de Freitas Manuel , da Fonte M.
Published: March 2009

Under constant amplitude loading, a single variable (K) or Kmax are required in crack
growth relationships. The transferability of fatigue laws, obtained under constant amplitude loading
to variable amplitude fatigue, requires at least an additional variable, whose evolution with crack
length accounts for the interactions effects between cycles of different types. This paper presents an
analysis of fatigue crack growth tests on M(T) specimens made of a medium carbon steel. The
specimens are subjected to repeated blocks of cycles made up of one or several overloads separated
by a variable number of baseline cycles and two baseline stress ratios. The main objective of this
study is to better understand the mechanisms at the origin of interactions effects due to the presence
of overloads (or underloads) at different locations of each block loading. Results have shown that
the interaction effects are closely related to the cyclic plastic behaviour of the material and also the
so-called Bauschinger effect.
Influence of Temperature and Increasing Traffic Flow on the Fatigue Damage of Welded Bridge Decks
Authors: Guo Tong , Li Ai Qun , Li Zhao Xia
Published: March 2009

Fatigue life assessment of critical bridge members using online monitoring data has been
investigated in recent years. To make a quick and efficient evaluation, a representative block of strain
cycles is usually defined. However, such block sometimes fails to cover the change in fatigue damage
by temperature fluctuation and traffic growth, which is important to the life prediction of the welds in
a long-span suspension bridge. To find the influence of temperature and traffic volume on the fatigue
damage, an equivalent vehicle load method is dedicated through finite element analysis, and the
statistical disposition of traffic flow has been conducted, using data from the Runyang Bridge. The
influence of traffic growth can be estimated and eliminated from the total damage so that the
temperature effect on the fatigue damage is finally obtained. It is found that temperature has a linear
effect on the fatigue damage. According to the fitted relationship between fatigue damage,
temperature and the traffic flow, a more objective fatigue assessment is undertaken, based on the
rain-flow counting method and the Palgren-Miner rule.
Monitoring Analysis for the Velocity of Crack Propagation
Authors: Chen Jing Xi , Zhang Guang , Zhang Hua , Guan Yali
Published: March 2009

The crack gauge sensor and pencil core sensor are two kinds of elements commonly used
to monitor the crack propagation velocity; both of them have the advantage of easy operation, low
price, etc. However, they also have the disadvantage, namely, bigger measuring error. In this paper,
the work principles of these two sensors are introduced, next, these two sensors are used to measure
the crack propagation velocity in the fracture mechanics experiment of gypsum plates, then
according to the experimental results, the measuring errors are analyzed and the correcting methods
are suggested; at last, the crack propagation velocity are discussed, and the conclusion that the
starting velocity of propagation is a variable and related to the dynamic process and the restrained
conditions is pointed out.
Initial Aspects of Low-Cycle Fatigue Fracture of Martensitic Steels
Authors: Eterashvili Tamaz , Dzigrashvili T. , Vardosanidze M.
Published: March 2009

This study deals with the SEM and optical microscopic characterization of fatigue
plastic deformation process during fatigue crack initiation to understand where, why and how
cracks initiate under conditions of low cycle fatigue. Samples were prepared from the
13Х11Н2В2МФ high-chromium stainless steel used for fusion power applications. The low-cycle
tests were conducted at room temperature with the standard V-notched samples prepared from
conventional stainless steel. The following characteristics were studied during fatigue tests: 1
macrocrack propagation, 2. interaction between macrocrack and isolated microcracks, 3. interaction
between macrocrack and slip bands, 4. interaction between macrocrack and microstructure elements
of the steel.
The above experiments show that during macrocrack propagation a plastic zone is formed around it,
where isolated microcracks and slip bands of 2-3 different directions are observed. Measurement of
plastic zone dimensions after different number of cycles of deformation show that plastic zone size
increases during the first stage of cyclic deformation (until definite number of cycles are
completed), and then remains unchanged. The observations show that main crack is composed of
individual micro-components, the lengths of which are in a good correlation with the dimensions of
microstructure elements of the steel (former austenite grains, martensite crystals). It was revealed
that during growth, as a rule, macrocrack rarely propagates along isolated microcracks and slip
bands. Direction of macrocrack propagation changes while passing from one microstructure
element to another, so that main direction is the same.
No preferable transcrystalline or intercrystalline propagation of macrocrack has been observed in
the investigated steel. It is shown that after subsequent fatigue tests, dimensions of the previously
created slip bands increase, and additional new slip band are also formed. The sites and frequency
of slip bands’ formation in plastic zone are also studied. It was observed that the boundaries and
mainly the sites of intersection of martensite crystals are the sites of isolated (rough) microcracks’
formation. The dimensions of slip bands are comparable with those of martensite crystals. The
angles between the main crack propagation direction and slip bands varied from 30o to 60o,
however, most of the slip bands were oriented at 45o to the main crack.
Based on the obtained results a conclusion is made that plastic deformation in samples go
inhomogeneously. In plastic zones, along with the heavily deformed areas, almost non-deformed
areas are also observed. The speed of fatigue fracture increases with the increase in frequency and
amplitude of deformations. Generally, the annealed samples are destructed prematurely in
comparison with non-annealed ones of the investigated steel.
Numerical Analysis of the Anisotropic Damage Evolution due to a Growing Mixed-Mode Crack
Authors: Molla-Abbasi Kianoush , Schütte Henning
Published: March 2009

Damage of materials is a progressive physical process through which the macroscopic
properties of the material changes and it might end with the final failure of a part and in some cases
can be disastrous. The main mechanism of brittle damage is the nucleation and growth of
microcracks. A way to model the anisotropic damage is to consider its influence on the
compliance/stiffness of the material at the meso-level.
A numerical study of a growing mixed-mode internal crack in a unit cell was undertaken with
the help of a finite element simulation. The model enables us to measure the components of the
elastic compliance tensor modified by damage as the crack grows, showing the evolution of the
anisotropic damage and the evolution of the type of material symmetries. The evolution of the
elasticity tensor shows that the damage associated with a growing elliptical crack changes the virgin
isotropic properties into orthotropic ones and by crack growth the axes of orthotropic symmetry,
initially aligned with the local coordinates of the crack, rotate towards the principle loading axes.
The matrix material of the unit cell is considered to be isotropic linear elastic, homogenous and
the response is perfectly brittle. The characteristic crack size is small compared to the unit cell, so
that the non-interacting crack assumption for the damage models is fulfilled. Crack propagation is
simulated using the stepwise method, which consists of the succession of straight segments and
crack growth is governed by the principle of maximum driving force which is a direct consequence
of the variational principle of a cracked body in equilibrium and considers the effect of all three
stress intensity factors. Without any ad hoc assumption, the crack growth rate is calculated using its
thermodynamic duality with the local maximum driving force.
Fatigue Strength of Three Dimensional Welded Joints: A Synthesis Based on the Strain Energy Density over a Control Volume
Authors: Zappalorto M. , Berto Filippo , Lazzarin Paolo
Published: March 2009

A recent approach based on the local strain energy density (SED) averaged over a given
control volume is applied to well documented experimental data taken from the literature, all related
to steel welded joints of complex geometry. This small size volume embraces the weld root or the
weld toe, both regions modelled as sharp (zero notch radius) V-notches with different opening
angles.
The SED is evaluated from three-dimensional finite element models by using a circular sector with
a radius equal to 0.28 mm. The data expressed in terms of the local energy fall in a scatter band
recently reported in the literature, based on about 650 experimental data related to fillet welded
joints made of structural steel with failures occurring at the weld toe or at the weld root.
A Study on Water Penetration of Concrete under Water Pressure to Develop the Anti-Corrosion Repair System
Authors: Yoo Joh Yeong , Lee Han Seung , Tae Sung Ho , Chul Moon Byung
Published: March 2009

As concrete is a type of porous materials, water or air freely permeates concrete. Therefore
the durability of concrete decreases. However, porous material with a rust inhibitor may allow
permeation of water into concrete. In addition, there may be permeation of water through the rust
inhibitor at the location of steel frames. The objective of the study is to investigate the penetration
depth of concrete under water forced conditions with pressure.
Characteristics of High Frequency Peening Methods and their Effects on the Fatigue Strength of Welded Details
Authors: Weich Imke , Ummenhofer Thomas
Published: March 2009

Research has been initiated on the effects of high frequency peening methods on the
fatigue strength. These methods combine an improvement of weld toe profile with an initiation of
compressive residual stresses and surface hardening. The effects of two techniques, High Frequency
Impact Treatment (HiFIT) and Ultrasonic Impact Treatemnt (UIT) are compared. Laser
measurements of the weld seam prove that both methods increase the overall weld toe radii.
Further, residual stress measurements verify the introduction of compressive residual stresses at
least up to a depth of 1 mm. The values meet the yield strength combined with an increase of the
surface hardness. These material mechanical effects cause an increased crack resistance. Crack
detection methods prove that the material mechanical effects yield to a retarded crack initiation.
Experimental results show that these effects lead to a significant increase of the fatigue strength and
reduced slopes of the SN-curves.
Shear Retrofitting Effect of RC Beams Damaged by Corrosion of Stirrup Strengthened with CFS
Authors: Tae Sung Ho , Lee Han Seung , Kim Tae Soo
Published: March 2009

In this study, an Ohno's anti-symmetric shear loading test was conducted after
strengthening reinforced concrete (RC) beams damaged by corrosion of stirrup, with carbon fiber
sheets (CFS) with a view to reviewing the effect of CFS on shear strengthening. As a result, it was
found that CFS like stirrups could take shear stress, and that shear strength could be increased by
using more CFS for reinforcement. It was also revealed that shear strength could be calculated by an
existing evaluation equation by properly evaluating the effect of CFS on shear strengthening, based
on the quantity of reinforcing CFS, ways of fixing the sheets and anchorage length as the effect on
shear strengthening varied depending on the fixing method while sheet anchorage increased
deformability.
Failure Analysis of Roller Neck at a Cardboard Production Plant
Authors: Göksenli Ali , Eryürek Barlas
Published: March 2009

In this paper corrosion-fatigue failure of a roller in a cardboard production plant has been
analyzed. The failure occurred at the bearing neck of the roller. Mechanical and chemical properties
of the roller are determined and the fracture surface is investigated. Forces applied on the roller is
examined, stress calculations are carried out and fatigue safety factor is calculated. Stress analysis is
also applied to roller and bearing neck by using Finite Element Method (FEM) and the results are
compared with the calculated values. Because of very high safety factor, reasons for failure are
investigated and effects of fatigue failure are determined. These effects are corrosion-fatigue,
working conditions and notch effect. In conclusion precautions which have to be taken to prevent a
similar failure is explained by using FEM.
2ODE-IPD: An Object-Oriented Design Environment for Robust and Reliable Interdisciplinary Product Design
Authors: Gayretli Ahmet
Published: March 2009

Electromechanical products such as electrical toothbrushes and robots carry multitechnological
characteristics, and functional operation of these systems is depended on the
successful operation of all system components. There are interactions between electronic and
mechanical components, software and other systems in complex products. These interactions such
as heat, vibration, gravity, corrosion and electromagnetism can lead to functional and financial
losses and failures of these kinds of products. The physical arrangement and mutual relation of subsystems
and parts are very important to design reliable and robust systems. However, designing
these products is complicated and time-consuming due to limitations on available expertise, tools,
and methods. This paper presents a new product development approach proposed for integrating
mechanical design with electronic design to improve design and manufacture of electromechanical
products in terms of customer requirements, reliability, structural integrity, weight, cost and time.
This approach has been implemented in a Delphi based environment integrated with a CAD system.
It assists in evaluating complex systems as far as parts relation and their possible effects on each
other, costs, weight and physical constraints are concerned in the early design process. This helps
the designers to avoid design iterations, and minimize the likelihood of failures and rapidly develop
reliable complex products subject to given constraints.
Propagation of Fatigue Cracks Emanating from Sharp Notches under Different Loading Direction
Authors: Benedetti Matteo , Beghini M. , Bertini L. , Fontanari V.
Published: March 2009

The present paper is aimed at investigating the behaviour of fatigue cracks emanating
from sharp V-shaped notches. To this purpose, several tests has been conducted on Al-7075-T651
notched specimens using a servohydraulic machine by changing the directions and levels of the
applied load. The crack growth have been interpreted on the basis of a linear elastic fracture
mechanics approach by adopting a weight function derived by the authors for the calculation of the
stress intensity factors (SIFs) of inclined edge-cracks emanating from V-shaped notches.
Study on the Prediction of the CO2 Absorption Quantity in the Concrete According to the Surface-Finishes
Authors: Lee Sang Hyun , Lee Han Seung , Lee Sung Bok
Published: March 2009

A cement which is used in construction and a concrete which is a hydration product of
cement is considered anti-environmental materials because of lots of CO2 emission in progress of
producing and making them. But a concrete absorbs CO2 gas in atmosphere after hydration and in
its lifetime. It is called carbonation. Based on Papadakis’ theses, this research is carried on
calculation of the CO2 absorption quantity in concrete. After research, we calculated the CO2
absorption quantity in concrete which has various surface-finishes and we evaluate each
surface-finishes the resistance against carbonation.
Residual Strength Research for Aluminum Alloy Sheet with Multiple Site Damage
Authors: Zhang Jian Yu , Wang Chuan Sheng , Bao Rui , Fei Bin Jun
Published: March 2009

This study investigated the residual strength of aluminum alloy sheet with multiple site
damage (MSD) through three types of aluminum specimens test. Aluminum panels with bare
collinear constant diameter holes were chosen as specimens. And there were saw cuts at both edges
of all the holes. After some constant amplitude tension-tension load cycles, the MSD were found in
these specimens since there were multiple fatigue cracks emanating from the saw cuts of holes. The
residual strength was recorded as the maximum load when every specimen was subjected to
monotonically increasing tensile load until failure occurred. The test results were compared with
predicted residual strength results by five different failure prediction criteria that were often used in
engineering in order to evaluate the accuracy of these criteria. The failure criteria included: fracture
criterion, net ligament loss criterion, ligament yield criterion, CTOA/CTOD criterion and average
stress criterion. Ligament yield criterion (Swift criterion) and average stress criterion got more
accurate prediction results than other criteria.
Effectiveness of Non-Linear Crack Mechanics under Plane Strain Conditions
Authors: Teranishi T. , Nisitani Hironobu
Published: March 2009

The non-linear crack mechanics (NLCM) is a concept assuring the occurrence of the same
phenomena in two cracked bodies under large scale yielding. It has been recognized that NLCM is
effective in the cases of plane stress conditions. In this study, it was made clear that NLCM is
effective not only in the case of plane stress condition but also in the case of plane strain condition.
Fretting Fatigue Phenomena on an all Aluminium Alloy Conductor
Authors: Boniardi Marco , Cincera Silvia , D'Errico Fabrizio , Tagliabue Chiara
Published: March 2009

This paper concerns about a failure analysis of an electric all aluminum alloy conductor
(AAAC) damaged and broken for fretting fatigue phenomena induced by aeolian vibrations.
Life of electric conductors is often reduced by various degradation mechanisms such as repeated
bending, fluctuating tension, distortion, fatigue, wear and corrosion phenomena. However the main
limiting factor of the electrical conductors is related to aeolian vibrations in the high frequency
range (between 5 to 50 Hz). Conductor oscillations may lead to fretting fatigue problems (otherwise
called fretting wear) caused by wind excitation, mainly in the suspension clamp regions, spacers or
other fittings. The induced aluminium wire fracture imply a drastic reduction in the transmission
line service. Vibration dampers are considered the most effective method to extend service life of
electric conductors, as they are the means to reduce fretting damage of aluminium wires.
The aim of the present work is to investigate the failure of an AAAC conductor of a 400kV
overhead transmission line (twin conductors) located in Touggourt Biskra (Algeria); the damaged
and broken conductors were operated in-service only for six months without spacers or dampers.
Three different types of conductors have been taken as experimental samples: the in-service broken
conductor, another in-service damaged conductor and a new conductor from warehouse as terms of
comparison. Samples have been analysed to identify the root cause of the failure and to verify the
conformity of the conductor elements to the international standards. The investigation has outlined
the morphology of the fretting damage: in all cases the fractured wires have shown typical static
deformation marks and dynamic fretting wear tangential marks associated with intense presence of
Al2O3 debris.
Numerical Simulation on Damage Effect of Explosion in Multilayer Mediums and Dimensional Analysis
Authors: Cheng Wang , Ning Jian Guo
Published: March 2009

A multilayer medium consists of compacted soil, gravel and concrete layers. The damage
law of multilayer mediums subjected to blast loading is investigated numerically at various charge
weights ranging from 1 to 10kg and burying depths ranging from 0 to 150cm. The numerical results
indicate that, in order to increase the energy utilization rate of explosives, charges less than 5kg
should be placed in the gravel layer to explode, while those more than 5kg placed in the compacted
soil layer. By use of dimensional analysis, the formula for damage effect of multilayer mediums
subjected to blast loading is consequently derived. Based on regression analysis of the numerical
results, the empirical expressions are established for the effects of charge weights and burying depth
on the crater radiuses in the concrete layer, the gravel layer and the compacted soil layer. The
expressions can be employed to assess the damage effect of charges blasting in multilayer mediums.
The Constitutive Model for Isotropic Damage of Geomaterial
Authors: Liu Yuan Xue , Zhou Jian Ting , Li Zhong You
Published: March 2009

A constitutive model for isotropic damage of geomaterial is put forward, and its numerical
computation procedure is given also. The calculated results for a simple example could highlight our
understanding about the mechanism of geomaterial damage, and several useful conclusions can be
drawn: The series assumption can not be used to synthesis mode of stress and strain for complexus
theory of geomaterials damage; strictly speaking, the parallel assumption can not be used to that of
geomaterials damage also; the complexus stress-strain behavior like that of ideal natural geomaterial
under small stress, and like that of reconstituted soil under large stress.
Stochastic Characteristics of Fatigue Crack Propagation for 2024-T3 Aluminium Alloy in Corrosive Environments
Authors: Bao Rui , Zhang Jian Yu , Fei Bin Jun
Published: March 2009

Crack propagation tests were conducted with CCT specimens made by 2024-T3 Aluminum
alloy in benign and corrosive environments to investigate the stochastic characteristics of crack
growth. A random variable probability crack growth model, base on the modified form of Paris law,
was used to characterize the stochastic performance. Distribution significance test has been done,
which shows that the random variable X can be considered reasonably to follow log-normal
distribution in all the 4 kind of environments. Variance analysis indicates that the scatter in wet air is
greater than that in laboratory air significantly. Expressions for the probability distribution of crack
size at any given loading cycle and the probability distribution of the random fatigue life at which a
given crack size is reached were discussed. The corresponding calculations for the crack length
distribution and P-a-N curves with certain reliability were carried out. The comparisons with
experimental data indicate the validity of the proposed method.
Modeling Crack Initiation and Propagation in Nickel Base Superalloys
Authors: Korsunsky Alexander M. , Song Xu , Belnoue Jonathan , Prakash Leo D.G. , Dini Daniele , Walsh Michael J.
Published: March 2009

Nickel base superalloys are the primary class of materials used in the manufacture of high
temperature components for gas turbine aeroengines, including combustion casings and liners, guide
vane and turbine blades and discs, etc. These components are subjected to complex cyclic loading
induced by the combination of mechanical loading, changing temperatures and thermal gradients,
inducing plastic deformation and creep, that ultimately may lead to crack initiation and propagation.
The purpose of the present paper is to provide a necessarily brief overview of recent modeling
activities in this field, including polycrystalline crystal plasticity modeling for the study of crack
initiation, coupled non-local damage-plasticity modeling for crack initiation and propagation
studies, and the incorporation of time and environment dependent processes (creep and oxidation) in
the predictive modeling of fatigue crack growth rates in nickel base superalloys.
Numerical Testing for Dynamic Fracture of Three Point Bending Cement Mortar Specimen with Off-Center Edge-Crack
Authors: Zou Guang Ping , Xia Pei Xiu
Published: March 2009

In this paper, RFPA－dynamic numerical simulation system was adopted to simulate the
entire process of the three–point bending specimen with off–center edge-crack propagation to the
specimen macroscopic crack which under the dynamic load function. And showed the whole process
of the cement mortar specimen crack propagation which under the dynamic load function, as well as
the whole field stress distribution picture, and has carried on analysis the specimen destruction
process, has pointed out the influence of the no dimension quantity a/L change to crack expansion
path and the destruction form.
Improvement of Fatigue Strength of Maraging Steel by Shot Peening
Authors: Kawagoishi Norio , Nagano Takanori , Moriyama M. , Kondo Eiji
Published: March 2009

Rotating bending fatigue tests up to 108 cycles were carried out to investigate the
effects of shot peening on the fatigue strength and the fracture mechanism in an 18 % Ni
maraging steel by using shot particles of various sizes or hardness. Fatigue strength was
increased markedly by shot peening in the wide region of fatigue life. The S-N curves showed
duplex S-N properties because of the transition of fracture origin from the specimen surface in
the short life region to the subsurface in the long life one. Double shot peening by using
super-hard fine particles was effective to improve the fatigue strength for surface fracture,
though the fatigue strength for an internal fracture was hardly influenced. These results were
discussed from the points of view of effects of surface roughness, residual stress and work
hardening on the fatigue strength.