bluuebunny/crossref_metadata_2025 huggingface dataset:
Fatigue Analysis of Structural Details of an Oceangoing LPG Ship
Authors: Rudan Smiljko , Tomašević Stipe , Senjanović Ivo
Published: March 2009

Structural details of ship structures are prone to fatigue damage mainly due to high-cycle
wave load and low-cycle cargo loading/unloading. Full stochastic fatigue analysis of selected
structural details on an oceangoing 6500 cbm LPG ship is presented. A critical Y-joint of
longitudinal bulkhead and bilobe tank shell as well as double-bottom girder details are selected due
to different reasons. The eccentricity of the Y-joint, leads to significant stress concentration. Saddle
supports of gas tanks cause stress concentration in ship double bottom due to weight and dynamic
loads. Wave load on ship structure is calculated using linear strip theory for ship in ballast condition
and full ship. Wave load is transferred to ship finite element model and notch structural stresses are
determined using finite element analysis. Stochastic fatigue analysis is then performed, taking into
account sailing route and other ship operational parameters. Finally, fatigue damage summation is
done and results are discussed.
Behavior of Cracked Materials
Authors: François Marc
Published: March 2009

Due to their microstructure, quasi brittle materials present rough cracks. Under sliding of
the crack lips, this roughness involves in one hand induced opening and in the other hand some apparent
plasticity which is due to the interlocking of the crack lips combined with Coulomb’s friction.
The proposed model is written under the irreversible thermodynamics framework. Micromechanics
uses the Del Piero and Owen’s structured deformation theory. Opening of the crack depends upon
the crack shape and the relative sliding of the crack lips. The thermodynamic force associated to the
sliding has the mechanical meaning of the force acting in order to make the crack slide. Yield surface
is defined as a limitation of this force with respect to the Coulomb’s friction and the Barenblatt cohesion.
The crack orientation is defined as the one for which the criterion is reached for the lowest stress
level. A decreasing cohesion, respect to sliding is supposed. Tension and compression reference cases
are envisaged.
DBEM Crack Growth Simulation for a Riveted Aeronautic Reinforcement under Non-linear Contact Conditions
Authors: Citarella Roberto G. , Lepore M. , Apicella A. , Calì C.
Published: March 2009

A special specimen was created cutting a rectangular notched area from the surrounding
of the upper left corner of a wide body aircraft door. Then a fatigue traction load was applied in
order to induce an MSD crack initiation and propagation. An innovative DBEM (Dual Boundary
Element Method) modelling approach was devised, capable of explicitly modelling the different test
article layers with their rivet connections even in a 2d approach. The rivets that are close to the
propagating crack are coupled with the corresponding holes by non linear contact conditions, and
the accuracy improvements are assessed in comparison with a previous linear analysis, in which
traction and displacements continuity conditions on the hole-rivet interface had been imposed.
The importance of such influence on the simulation precision need to be assessed due to the strong
impact that a non linear analysis produces on computational times.
For such a complex problem (three different panels, made of different materials, each one with a
variable thickness and connected by numerous rivets), experimental crack propagation data were
available for the numerical-experimental comparison. With such non linear approach, a significant
improvement on the growth rate correlation is obtained, that justify the increased computational
effort.
Micro-Damage Mechanisms and Property Fluctuation of Recycled Aggregate Concrete
Authors: Xiao Jian Zhuang , Liu Qiong , Du Jiang Tao , Zhang Chuan Zeng
Published: March 2009

In this paper, the basic damage mechanisms and the primary reasons for the property
fluctuation of recycled aggregate concrete are investigated experimentally. By a comprehensive
literature study and systematic laboratory tests, the interactions between the old and the new interfaces
in recycled aggregate concrete are analyzed. In particular, the damage initiation and evolution
mechanisms on the old and the new interfaces are studied in details. The essential factors affecting the
fluctuation and its extent are investigated from the point of view of material sciences. The present
results imply that the qualitative and quantitative changes of the old and the new interfaces during the
loading process induce a notable fluctuation of the mechanical and the physical properties of recycled
aggregate concrete. To reduce the fluctuation and improve the mechanical properties of the recycled
aggregate concrete, effective controlling and processing measures are suggested and discussed.
New Fatigue Model for Service Life Assessment of Last Stage Blade in Steam Turbine Based on Liquid Corrosion and Dynamic Stress
Authors: Xie Yong Hui , Zhang Di , Feng Zhen Ping
Published: March 2009

Forced vibration and liquid corrosion are important reasons for last stage blade failure in
steam turbine. In order to improve reliability of blades in wet steam stages, the dynamic stress and
the liquid-solid impact stress of blade were analyzed firstly, then Neuber’s rule, rainflow counting
method and improved cumulative damage rule were introduced to develop a new model to evaluate
service life of last stage blade. Many factors such as manufacturing quality, metal quality and
operation status were considered, so it is more reasonable for service life assessment of last stage
blade. At last, the service life of a last stage blade of 680mm was analyzed and the result
approximates the practical service life. It is shown the new fatigue model can give some significant
data and is usable for engineering application.
Optimum Dosage of PP Fiber for the Spalling Control of High Strength Reinforced Concrete Columns
Authors: Yoo S.H. , Shin S.W. , Kim I.K.
Published: March 2009

Spalling is defined as damages to concrete exposed to high temperature during fire,
causing cracks and localized bursting of small pieces of concrete. As the concrete strength
increases, the degree of damage caused by spalling becomes more serious due to impaired
permeability. It has been reported that polypropylene(PP) fiber has an important role in protecting
concrete from spalling, and the optimum dosage of PP fiber is 0.2%. However, this result was based
on the fire test of non-reinforced concrete specimens. The high-temperature behavior of highstrength
reinforced concrete columns with various concrete strength and various quantity of PP
fibers is investigated in this study. The results revealed that the ratio of unstressed residual strength
of columns increased as the concrete strength increased and as the quantity of PP fiber increased
from 0% to 0.2% the residual strength of columns increase. However, the effect of PP fiber quantity
on residual strength of column was barely above 0.2%.
Finite Element Analyses of Cracks in Piezoelectric Structures
Authors: Kuna Meinhard
Published: March 2009

A review is given about FEM-techniques to compute the coupled electromechanical
boundary value problem of cracks in piezoelectric structures under static and dynamic loads. To
calculate the relevant fracture parameters very precisely and efficient, the following numerical
techniques are presented: i) Special singular crack tip elements, ii) Modified crack closure integral,
iii) Computation of electromechanical J-integral and iv) Usage of interaction integrals. Special
emphasis is devoted to different electric crack face boundary conditions. The accuracy, efficiency
and applicability of these techniques are examined by various example problems and discussed with
respect to their advantages and drawbacks for practical applications.
Determination of the Fatigue Behavior of Aluminide Coatings by Means of the Impact Testing Method
Authors: David Kostas , Anthymidis K.G. , Agrianidis P. , Tsipas D.N.
Published: March 2009

The impact testing is an efficient experimental method that enables the quantitative and
qualitative determination of the fatigue resistance of mono- and multilayer coatings deposited on
various substrates, which was not possible with the common testing methods previously available.
In this paper the experimental assessment of the fatigue resistance of coatings working under cyclic
loading conditions by means of the dynamic impact testing method is presented. The fatigue failure
mode, such cohesive or adhesive, of the investigated coatings is determined using scanning electron
and optical microscopy, as well as EDX analysis. Critical values of the stress components,
responsible for distinctive fatigue failure modes of the coating substrate system are obtained and the
fatigue limits of aluminide coatings are illustrated in simple diagrams containing the impact load
versus the number of successive impacts that the examined aluminide-P91 system can withstand.
The Damping Effect on Constant-Ductility Seismic Demand Spectra of Inelastic Structures
Authors: Zhai Chang Hai , Zhang Mao Hua , Xie Li Li
Published: March 2009

The constant-ductility seismic demand spectra can provide high-sight of seismic damage
mechanism of inelastic structures under the earthquake. And in the displacement-based seismic
design, the constant-ductility seismic demand spectra are very useful for the preliminary design of
new structures where the global displacement ductility capacity is known, which can provide the
required inelastic lateral strength of new structures from the required elastic lateral strength. An
in-depth investigation of damping effect on constant-ductility seismic demand spectra of inelastic
structures is presented in this paper. A statistical study is performed of inelastic response computed
for different damping ratio SDOF systems with different levels of lateral yielding strength required to
maintain the given displacement ductility when subjected to a large number earthquake accelerations.
It is concluded that the damping effect on constant-ductility seismic resistance spectra is rather
complex. It depends on not only site conditions but also the structural period. Finally, results from
non-linear regression analysis are presented that provide a simplified expression to be used to
approximately quantify the damping effect.
An Evaluation of Fatigue Crack Growth in a Reactor Steel in Air and Water Environments Considering Closure Effects
Authors: Černý Ivo , Linhart Václav
Published: March 2009

The paper contains results of an experimental programme aimed at an evaluation of
fatigue crack growth rate and threshold conditions in a reactor pressure vessel steel. Though the
main target of the work was to gain a data basis for possible future needs of defect and risk
assessment, an emphasis was put on an evaluation of crack growth mechanisms, too. It was shown
that despite some recent works infirming crack closure phenomenon itself or methods of its
evaluation, crack closure explained near-threshold fatigue crack behaviour in the specific case of
the reactor steel in air conditions and was in a direct consistency with results of fractographical
analyses. A fairly recent model of partial crack closure was very suitable for an explanation of an
unexpected fatigue crack growth behaviour in water environment, when fatigue crack growth rates
were rather irregular and significantly lower that in air.
Crashworthiness Optimization of Crash Box in Automotive Structure
Authors: Ghasemnejad H. , Hadavinia H. , Simpson G.
Published: March 2009

In this paper the energy absorption of thin-walled aluminium tubes used as crash boxes in
the body structure of a vehicle has been optimized. In order to achieve this, various cross-sections
of extruded aluminium were chosen and their behaviour under dynamic impact loading was
investigated. The crash boxes were made from aluminium alloy 6060 temper T4. Finite element
software LS-DYNA in ANSYS was used for modelling. For each cross-section, the results of
dynamic crushing load versus crushing distance was obtained from the FE simulation and the
results were compared with the experimental and numerical work on a square crash box in the
literature. Parameters such as the crush force efficiency and the specific energy of various crash
boxes were compared with the relevant ones for the square crash box and the most efficient crash
box was recommended.
Optimum Design of Construction Machine Parts
Authors: Hattori Nobusuke , Nishida Shinichi , Igawa H.
Published: March 2009

In this research, the authors have tried to decrease the weight of circular-digging large size
bucket as far as possible with keeping the reliability of whole of the construction machine. In the case
of main bucket, the authors have evaluated the strength reliability of this bucket and proposed more
optimum design changing the thickness and kind of the material, though the expected weight
reduction ratio becomes only 5% with increasing the rigidity of the main bucket. In the case of
sub-bucket, it is desirable to change the thickness of the material and to attach the reinforcement in the
both side. Therefore, the designer could reduce the weight by 11% with keeping the rigidity of the
sub-bucket.
Solution Methods for General Stress Concentrators in Anisotropic Heterogeneous Media
Authors: Kotoul Michal , Profant Tomáš , Ševeček Oldřich , Krejcir Martin
Published: March 2009

The increasing use of fibre-reinforced composites in high performance structures has
brought a renewed interest in the analysis of cracks, wedges, and multi-material wedges in
anisotropic materials. This paper will address three crucial stages of the general stress concentrator
analysis: i) numerical procedures for the determination of eigenvalues and eigenvectors in
Williams-like asymptotic expansion for multi-material wedge; ii) approaches to an accurate
calculation of the near crack tip fields – the application of so-called two-state (or mutual)
conservation integrals; iii) application of fracture criteria for the assessment of fracture inception at
the general stress concentrators - concept of the so called finite fracture mechanics.
Micro- and Macro-Approach to the Fatigue Crack Propagation in High-Strength Pearlitic Steel Wires
Authors: Toribio Jesús , Gonzáles B. , Matos Juan Carlos , Ayaso F.J.
Published: March 2009

This paper analyzes how the cold drawing process influences the fatigue behaviour of
eutectoid steel, with special emphasis on the role of microstructural changes induced during such a
manufacturing process. Fatigue cracks are transcollonial and exhibit a preference for fracturing
pearlitic lamellae, with non-uniform crack opening displacement values, micro-discontinuities,
branchings, bifurcations and frequent local deflections that create microstructural roughness. The
net fatigue surface increases with cold drawing due to the higher angle of crack deflections.
The Parametric Study of the Crack Growth in the Lubricated Rolling-Sliding Contact Problems
Authors: Potočnik Roki , Flašker Jože , Zafošnik Bostjan , Glodež Srečko
Published: March 2009

A two-dimensional numerical model is used to describe the crack path in the lubricated
rolling-sliding contact problems. The model assumes that the crack is initiated in a pre-existing
micro pit, which resulted from the crack growth on the surface of a gear tooth flank. The lubricated
rolling-sliding contact problem is modelled using the Hertz theory of contact, the Coulomb's law of
friction and hydraulic pressure mechanism with constant pressure which simulates the effect of
lubricant trapped into the crack. Different load cases are used to simulate the moving of a contact
load. The crack propagation path is evaluated by a maximum tangential stress criterion and
modified maximum tangential stress criterion which considers the stress intensity factors KI and KII,
the T-stress, the critical distance ahead the crack tip rc, and the stress on the crack surfaces. The
computational results show that the consideration of the T-stress has a significant influence on the
crack path in the lubricated rolling-sliding contact problems.
Crack Identification in Gear Tooth Root Using Adaptive Analysis
Authors: Belsak Ales , Flašker Jože
Published: March 2009

Problems concerning gear unit operation can result from various typical damages and
faults. A crack in the tooth root, which often leads to failure in gear unit operation, is the most
undesirable damage caused to gear units. This article deals with fault analyses of gear units with real
damages. A laboratory test plant has been prepared; it has been possible to identify certain damages
by monitoring vibrations. In concern to a fatigue crack in the tooth root significant changes in tooth
stiffness are more expressed. When other faults are present, however, other dynamic parameters
prevail. Signal analysis has been performed also in concern to a non-stationary signal, using the
adaptive transformation for signal analysis.
Investigation of a Mode III Crack in Functionally Graded Magnetoelectroelastic Materials
Authors: Wang Bao Lin , Zhang H.Y.
Published: March 2009

In this study, an anti-plane crack in a functionally graded magnetoelectroelastic materials
is investigated. It is assumed that the material properties such as elastic stiffness c44(y), piezoelectric
coefficient e15(y), dielectric constant ε11(y), piezomagnetic coefficient α15(y), magnetoelectric
coupling coefficient μ11(y) and magnetic permeability υ11(y) vary one-dimensionally on the ycoordinate
with a series of functions f(y).An asymptotic analysis is done and the problem is solved
by means of singular integral equation technique. The influence of the material inhomogeneity on
crack tip stress, electric displacement and magnetic induction intensity factors are studied. The
results are considered to reveal the effect of material inhomogeneity and geometry of the crack on
the field intensity factors.
Damage Detection of Building Structures Using Ambient Vibration Measurement
Authors: Yoo S.H. , Kim S.Y. , Shin S.W.
Published: March 2009

System identification(SI) techniques using dynamic responses and behaviors of structural
systems become an outstanding issue of researchers. However the conventional SI techniques are
identified to be non-practical to the complex and tall buildings, due to limitation of the availability
of an accurate data that is magnitude or location of external loads. Thus a technique to estimate
structural properties of building without input measurement data and using limited response is
essential in structural health monitoring. In this study, the improved least square method for damage
detection is proposed and verified by shaking table tests on three-story plane frame steel structures.
In results damage detection was performed in each member level.
Structural Optimization of Laminated Composite Plates for Maximum Buckling Load Capacity Using Genetic Algorithm
Authors: Soykasap Omer , Karakaya Şükrü
Published: March 2009

In this study, the structural optimization of laminated composite plates for maximum
buckling load capacity is performed by using genetic algorithm. The composite plate under
consideration is a 64-ply laminate made of graphite/epoxy, is simply supported on four sides, and
subject to in-plane compressive static loads. The critical buckling loads are determined for several
load cases and different plate aspect ratios using 2-ply stacks of 02, ±45, 902. The problem has
multiple global solutions, the results of which are compared with previously published results.
FEM Simulation and Experimental Test on Residual Stress of Cold Expansion Hole of Rectangular Plate
Authors: Shao Xiao Jun , Liu Jun , Liu Yong Shou , Yue Zhu Feng
Published: March 2009

A 2D rectangular plate model has been established to study the residual stress fields of
cold expansion hole. Experiments were carried out to measure the residual stress of cold expansion
hole and verify simulation results. The FEM results show, with interference values developing, the
maximum values of circumferential residual compressive/tensile stress increase and higher positive
stress values are obtained at the boundary of the rectangular plate. However, higher positive stresses
at the boundary of plate are harmful to the capacity of fatigue resistance, the determinations of best
interference value to a certain wide plate were proposed. Finally, the effect of the plate width on the
residual stress distribution was analyzed.
Analysis on the Temperature Field when Crack Arresting in an Axial Symmetry Metal Die by Pulse Current Discharged
Authors: Zheng Li Juan , Fu Yu Ming
Published: March 2009

When a suitable pulse current is introduced into a metal die containing a crack, the current
concentration effect is immediately apparent, small welded joints are formed at a small sphere near
the crack tip inside the metal die by metal melting as a result of the heat concentration effect. An axial
symmetric metal die with a half–embedded crack on the top face is the object studied. The high
intensity pulse current is switched on and flows from the outer to the inner surface of the hollow metal
die. The complex function method is used to solve for the temperature field around the crack tip at the
moment when the pulse current is switched on. The expression for the temperature field provides the
basis for determining the current density and current direction. The experiment surveys show that the
temperature around the crack tip grows up instantly above the melting point of the metal, the round
crack tip is melted.
The Effect of Cracks on Chloride Penetration into Concrete
Authors: Yoon In Seok , Schlangen Erik , Rooij Mario R. de , van Breugel Klaas
Published: March 2009

This study is focused on examining the effect of critical crack width in combination with
crack depth on chloride penetration into concrete. Because concrete structures have to meet a
minimum service-life, critical crack width has become an important parameter. Specimens with
different crack width / crack length have been subjected to rapid chloride migration testing (RCM).
The results of this study show a critical crack width of about 0.012 mm. Cracks smaller than this
critical crack width are considered not to have a significant influence on the rate of chloride transport
inwards, while chloride penetration does proceed faster above this critical crack width.
Investigation into Damage of Aluminum Gas-Filled Pressure Vessels under Hypervelocity Impact
Authors: Guan Gong Shun , Pang Bao Jun , Ha Yue
Published: March 2009

Impacts of meteoroids and space debris on pressure vessels can have detrimental
consequences for any mission. Depending on the parameters of the impacting particle and the
characteristic of the vessel, the damages can range from relatively uncritical craters in the vessel’s
surface to the catastrophic bursting of vessels, which besides the loss of vessel may result in severe
secondary damages to surrounding components. In order to investigate failure mechanisms of
thin-walled aluminum pressure vessels under hypervelocity impact of space debris, a non-powder
two-stage light gas gun was used to launch Al-sphere projectiles impacting on unshielded and
shielded vessels. Damage patterns and mechanisms leading to catastrophic rupture are discussed.
Experimental results indicate that the impact kinetic energy of the projectile and the gas pressure in
the vessel have an important effect on the damage modes of the vessel. On the one hand, high pressure
gas can lead to a vessel blast. On the other hand, high pressure gas can mitigate the impact of the
debris cloud on the rear wall of the vessel. Catastrophic rupture of unshielded gas-filled vessels can
be avoided when the impact energy is less than a certain limit value. When the bumper is perforated,
damage of shielded pressure vessel might be fatal for vessels with high gas pressure.
The Asymptotic Elastic-Viscoplastic Field at Mode I Dynamic Propagating Crack-Tip
Authors: Wang Zhen Qing , Wang Ji Bin , Liang Wen Yan , Su Juan
Published: March 2009

The viscosity of material is considered at propagating crack-tip. Under the assumption
that the artificial viscosity coefficient is in inverse proportion to the power law of the plastic strain
rate, an elastic-viscoplastic asymptotic analysis is carried out for moving crack-tip fields in
power-hardening materials under plane-strain condition. A continuous solution is obtained
containing no discontinuities. The variations of the numerical solution are discussed for mode I
crack according to each parameter. It is shown that stress and strain both possess exponential
singularity. The elasticity, plasticity and viscosity of material at the crack-tip only can be matched
reasonably under linear-hardening condition. The tip field contains no elastic unloading zone for
mode I crack.
Theoretical Model for Interfacial Nonlinear Bond Softening Behavior between Embedded Steel and HSHPC
Authors: Zheng Shan Suo , Li Lei , Deng Guo Zhuan , Che Shun Li , Zhao Wei
Published: March 2009

The latest experimental study on steel reinforced high strength and high performance
concrete (SRHSHPC) specimens shows that there exists interfacial bond softening phenomenon
between embedded steel and high strength and high performance concrete (HSHPC), and it makes the
shear transfer capacity between shaped steel and HSHPC be progressively reduced. To predict
failure load in design, a theoretical model for interfacial bond softening behavior is required. As
interfacial bond softening behavior is a nonlinear process involving material properties, it can be
analyzed once the relation of interfacial bond stress (τ ) and slippage ( s ) is known. In this paper, the
mechanism of interfacial bond-slip is studied, thus a simplified τ − s relation including ascending and
descending parts is proposed and employed to analyze the interfacial nonlinear bond-slip process.
Based on the interfacial equilibrium between steel and HSHPC as well as the τ − s relation, the basic
governing equations in both softened region and elastic region are established and solved for steel
strain or stress. At last, the application of the model is verified through comparison with experimental
results. The calculating results of the model are found to be in good agreement with experimental
results, showing that the model can describe the bond-slip process in real material systems.
Finite Element Analysis of the Cohesive Zone across a Strength Mismatched Bimetallic Interface
Authors: Ukadgaonker Vijay G. , Bhat Sunil
Published: March 2009

When a Mode I crack in soft steel body grows and reaches near the perpendicular interface of ultra
strong steel body, its cohesive zone penetrates into the interface body which influences the crack tip
parameter. The paper presents finite element analysis of the cohesive zone across the interface of
such elastically matched but strength mismatched bodies in linear elastic regime. Parent alloy steel
(ASTM 4340) body and interface maraging steel (MDN 250) body are considered for analysis. The
cohesive zone is modeled in accordance with the Dugdale criterion. J integral is evaluated over the
path around the interface to examine the effect of cohesive stresses on the crack tip. The results are
compared vis-à-vis those obtained from the theoretical model. The two are in very good agreement
with each other.
Study on Interfacial Crack Propagation and Fracture between Embedded Steel and HSHPC
Authors: Zheng Shan Suo , Li Lei , Deng Guo Zhuan , Zhang Liang
Published: March 2009

Steel reinforced high strength and high performance concrete (SRHSHPC) specimens were
experimented to study the mechanical behaviors between steel and concrete interface. In experiment,
interfacial bond softening process was observed, which can be explained in terms of damage along the
interface, leading to progressive reduction of shear transfer capability between steel and high strength
and high performance concrete (HSHPC). In this paper, bond softening process along the interface is
considered in the analysis of crack-induced debonding. Interfacial bond-slip mechanism between
steel and HSHPC is studied in detail based on fracture mechanics. With the help of acoustic emissions
technology, the crack propagation in the interlayer was observed, thus the interfacial crack
propagation and fracture model is set up. Under the assumption that the interlayer is weak concrete
compared with concrete matrix, the stress field as well as displacement field around the crack tip is
deduced. The characteristics of interfacial fracture process are discussed and a model for interfacial
fracture process zone is built up. With this model, the size of fracture process zone can be derived. At
last, the influence of the fracture process zone on interfacial fracture toughness is determined using
critical fracture toughness. All these may contribute to improvement of theory for SRHSHPC
composite structure.
Experimental Analysis on the Fatigue Threshold Behaviour of a Nitrided and Shot Peened Steel
Authors: Guagliano Mario
Published: March 2009

The effectiveness of the application of shot peening after nitirding for improving the
fatigue strength of high-performance steel components has not been adequately treated in literature,
and it is not clear if shot peening can really and drastically increase mechanical performances of
nitirded elements. In this paper an approach to assess the influence of shot peening on nitrided
components is presented. It is based on fracture mechanics concepts. Smooth specimens with a
micro-hole acting as a pre-crack were fatigue tested. The values of micro-hardness and of the
residual stresses were measured and related to the experimental results. By elaborating the results it
was possible to determine the threshold values of the stress intensity factors of the nitrided and shot
peened material. A formula to predict the value of Kth of shot peened and nitrided steels is
proposed.
A New Correction Procedure to Correct the Predicted Crack Extension Direction of a Mixed Mode Crack Path
Authors: Lucht Tore , M.H.Aliabadi Ferri
Published: March 2009

In an incremental crack extension analysis each crack increment is in general modelled
with a straight extension. In order to avoid introduction of an error when the local crack growth
criterion is used with an incremental formulation, each straight crack extension would have to be
infinitesimal as the crack growth direction changes when the crack grows. A correction procedure to
correct the extension direction of the increment can however be applied to ensure that a unique
crack path is achieved with different analyses of the same problem performed with different size of
the crack-extension increments. A proposed correction procedure and an reference correction
procedure are demonstrated by solving a computational crack growth example. The demonstration
shows that analyses of the crack path performed with big crack extensions and the proposed crack
correction procedure are in excellent agreement with analyses of the crack path performed with very
small crack extensions. Furthermore it is shown that the reference correction procedure has a
tendency to overcorrect the crack growth direction if the stop criterion for the iterative correction
procedure is not specified for each new crack growth analysis.
Reliability of Fatigue Bahaviour of Weld Metal
Authors: Gubeljak Nenad , Vojvodič-Tuma Jelena , Predan Jožef , Tišma Zdravko
Published: March 2009

The fatigue behavior assessment of high strength low alloy steel has main importance for
reliable and safe service of welded structure. The mechanisms of fatigue crack initiation and
propagation always represent a potential danger of crack propagation during the exploitation of a
structure, which can lead to catastrophic failure. If the fatigue’s crack appear at the welded
structure it is important to reliable find loading regime which can reduce risk of failure for still
operating structure.
Development of a Prediction Algorithm for Column Shortening in High-Rise Buildings Using a Neural Network
Authors: Yang Won Jik , Yi Waon Ho
Published: March 2009

The objective of this study is to formulate and evaluate a new training algorithm of
Neural Network to predict the inelastic shortening of reinforced concrete members using the
column shortening data of high-rise buildings. The new training algorithm of Neural Network for
the prediction of column shortening focuses on component of input data and training methods. The
validity is examined by training and prediction process based on column shortening measuring data
of high-rise buildings. The polynomial fit line of measuring data is used as the training data instead
of measuring data. The result shows that the new Neural Network algorithm proposed in this study
successfully predicts column shortening of high-rise buildings.
Damage Detection by the Use of Wavelet
Authors: Zhao Xin Dong , Wang She Liang
Published: March 2009

Detection and identification of structural damage at the earliest possible stage is a vital
part of the monitoring and servicing of structural during their lifetime. In this paper, damage
monitoring is studied on some kinds of structures use wavelet analysis, such as plate, and
framework. The research shows this damage detection technique is made to determine the damage
occurring time, positions and degrees and to realize an early discovery and diagnosis on the damage,
which offers a basis for realizing lifespan prediction of the structure and ensuring safety of
engineering structure.
Numerical Simulation of Fracture Process of Concrete Dam due to Freezing and Thawing with Finite Element Method
Authors: Cao Li Juan , Li Shou Ju , Shangguan Zi Chang
Published: March 2009

Freezing and thawing damage is one of the major problems of concrete dams in cold
climate. Cracking and splitting are the most common results of freezing and thawing deterioration
in concrete dam. The cracking problem owing to freezing and thawing was investigated by making
sue of finite element methods. The interpretation of the mechanism of failure was also given. In
order to compute the thermal stress fields of concrete dam caused by freezing and thawing, the
temperature changes versus seasons is determined according to measured data. The temperature
fields of concrete dam versus seasons are simulated by using finite element method. Basing on the
computational results of the temperature fields of concrete dam, the thermal stress fields are
calculated numerically. The researches show that the first principal stress of concrete dam at
downstream surface can exceed the tensile strength of concrete material. The numerical simulation
results of fractured regions of concrete dam agreed with practical observed data.
Numerical and Experimental Study of a Crash Absorption Keel
Authors: Colombo Chiara , Vergani Laura , Modica Nino Ascone
Published: March 2009

Aim of this paper is to study the impact between the sailing boat keel and the ground and
to look for the optimal configuration of the bulb-keel-hull system able to direct the damage in the
bulb-keel zone avoiding the hull region. The research, which is carried out in collaboration with
Wally shipyard, requires firstly an accurate investigation of the bulb-keel-hull system geometry, of
the boat inertial properties and of the impact condition. Secondly, a numerical dynamic analysis by
means of the finite element method allows to model the impact and to determine how, during the
collision, the state of stress varies and how the kinetic energy is absorbed/dissipated. Starting from
these results, the performance of the present configuration is evaluated in several conditions and
some proposals for new design configuration are made. In particular the results carried out from the
new design analyses were evaluated comparing themselves to results obtained from experimental
studies.
Lateral Stress Effect on Fracture Quantities of a Crack in a Piezoelectric Medium
Authors: Viola Erasmo , Belmonte Claudia , Viola Giuseppe
Published: March 2009

The aim of this paper is to seek the solution to the electromechanical field equations for a cracked linear
piezoelectric body using an analytical approach which is based on the decomposition theorem of linear
algebra. The electroelastic fields around the crack tip are given. The energy release rate is written in terms of
those fields intensity factors.
Development of Damage Zone by Scattered Cracking around Crack Tips in Brittle Solids under Compression
Authors: Saimoto Akihide , Toyota Akira , Imai Yasufumi
Published: March 2009

Compression induced formation of a damage zone, which would result in a shear fault in
brittle solids is studied. In a compression test of flawed PMMA, an apparent damage zone composed
of large number of scattered cracks, which have no intersection but exist closely with each other, is
experienced. The damage zone first appears in a vicinity of tips of artificial flaw and then extends
gradually with increase of applied compression. The direction of extension of damage zone is
observed to incline about 0 30 from the axis of principal compression. A mechanism of the extension
of damage zone with increase of applied compression is discussed using a scattered cracking model. It
was found that each crack composing the damage zone has a possibility to open due to crack-to-crack
interaction and a localized tensile stress appears both inside and outside of the damage zone. The
localized tension appeared in the interior of the damage zone may increase crack density, while that of
appeared in the exterior of the damage zone could bring an extension of the damage zone.
Fabrication and Fuel-Cell Properties of Sm-Doped CeO2 Electrolyte Film by Electrophoretic Deposition
Authors: Nakayama Satoshi , Miyayama Masaru
Published: March 2009

Electrolyte films of Ce0.8Sm0.2O1.9 (SDC) were prepared on NiO-SDC anode substrates by electrophoretic deposition (EPD) for intermediate-temperature solid oxide fuel cells (SOFCs). Dense and crack-free films were fabricated by cofiring the films and substrates. A cell using an SDC electrolyte film with a La0.6Sr0.4CoO3-δ cathode exhibited a power density of 281 mW/cm2 and an electrolyte resistance of 0.064 cm2 at 600°C. The film formation of SDC by EPD was found effective in decreasing the electrolyte resistance.
Crystal Phase and Orientation Dependence of Electro-Optic Effect in Epitaxial PLZT an PZT Films
Authors: Satoh Keisuke , Sugama Akio , Ishii Masatoshi , Kondo Masao , Kurihara Kazuaki
Published: March 2009

Lanthanum-modified lead zirconate titanate and lead zirconate titanate epitaxial films with (100)
and (111) orientations were grown respectively on (100) and (111) niobium, lending conductivity to
strontium titanate through chemical solution deposition. This study investigated changes in the
ordinary and extraordinary refractive index no and ne induced in these films by an electric field
using the prism-coupling method. In the (100) epitaxial PZT 30/70 film, anisotropic electro-optic
effects arise from the Pockels effect. The isotropic electro-optic effect, which is no = ne , was
achieved on (100) epitaxial PLZT 8/65/35 and PZT 70/30 films.
Microstructure and Mechanical Properties of Nano-ZrO2 and Nano-SiO2 Particulate Reinforced AZ31-Mg Based Composites Fabricated by Friction Stir Processing
Authors: Chang C.I. , Wang Y.N. , Pei H.R. , Lee C.J. , Du X.H. , Huang J.C.
Published: March 2009

Friction stir processing (FSP) has been applied to fabricate 10~20 vol% nano-sized ZrO2
and 5~10 vol% nano-sized SiO2 particles into an Mg-AZ31 alloy to form bulk composites under
the FSP parameters of advancing speed of 800 rpm and pin rotation of 45 min/min. The
microstructures and mechanical properties of the resulting composites were investigated. The
clustering size of nano-ZrO2 and nano-SiO2 particles, measuring average ~200 nm was relatively
uniformly dispersed, and the average grain size of the both Mg alloy of the composites varied
within 1.0~2.0 μm after four FSP passes. No evident interfacial product between ZrO2 particles and
Mg matrix was found during the FSP mixing in AZ31-Mg/ZrO2. However, significant chemical
reactions at the AZ31-Mg/SiO2 interface occurred to form the Mg2Si phase. The mechanical
responses of the nano-composites in terms of hardness and tensile properties are examined and
compared.
A Review on Bolt Load Retention Test of Magnesium Alloys
Authors: Cao Wei , Zhang Cong Fa , Fan Tong Xiang , Zhang Di
Published: March 2009

The bolt load retention (BLR) test fixtures and behaviors of Mg alloys by main research
teams are reviewed. Parts of BLR test results are also presented. Since creep properties are relevant to
BLR, an approach to predicting BLR behaviors from creep curves is briefly introduced. The BLR test
fixtures and procedures in our study are also shown.
Influence of Processing Parameters on the Microstructure of (AlN+Mg2Si)/Mg Metal Matrix Composites
Authors: Zhang Cong Fa , Cao Wei , Fan Tong Xiang , Zhang Di
Published: March 2009

This article deals with the influence of processing parameters on the microstructure of
(AlN+Mg2Si)/Mg composites. Parameters such as stirring impeller shape and pouring temperature
are shown to control the distribution and size of reinforcements and the amount of “Chinese script”
type Mg2Si.
Functional Properties of BaTiO3/Ni Composites
Authors: Huang Y.C. , Tuan Wei Hsing
Published: March 2009

In the present study, the BaTiO3/Ni composites were prepared by using the pressureless sintering technique. The ferroelectric and ferromagnetic properties of the composites are measured. The composites exhibit ferroelectric properties only when the Ni content is as low as 1 vol.%. Nevertheless, the saturated magnetization of the BaTiO3/Ni composites increases with the increase of Ni content. The BaTiO3/Ni composites exhibit multiferroic characteristics.
High Energy Planetary Ball Milling of SiC Powders
Authors: Pan Yu Bai , Huang Zheng Ren , Jiang Dong Liang , Mazerolles Léo , Michel D. , Pastol J.L. , Wang Guillaume
Published: March 2009

The effects of high-energy ball milling on SiC powders were studied using a planetary
apparatus. Conditions to obtain nanostructured SiC powders with an average crystallite size of 4 nm
were determined and powders were characterized by XRD, SEM and TEM analyses. This process
was applied to prepare fine powders leading to dense SiC ceramics by sintering at 1900oC for 30
minutes under 30 MPa in argon.
Fabrication of Highly Electroconductive Ceramics by Spark Plasma Sintering of Si3N4-Based Particles Coated with Nanosized TiN Prepared via Chemical Route
Authors: Shimada Shiro , Kawano Shuichi
Published: March 2009

TiO2 coating on Si3N4-based materials powders (Si3N4, α-Y-sialon, β-sialon) was accomplished by heating the powder suspension containing the precursor (1.0 vol% H2O + Ti(O-i-C3H7)4) from 15 to 40 °C. The success of homogenous coating was confirmed by TEM observation. TiO2 coated on the powder is nitrided with NH3 gas at 800 oC to TiN with uniform particle size 10–20 nm. Spark plasma sintering of composite TiN/ Si3N4-based particles at 1400 - 1600 °C yielded the composite ceramics with a relative density > 96% without sintering additives. Sintered TiN/ Si3N4-based composite ceramics containing 17.5 - 25 vol.% TiN showed a higher electrical conductivity > 103 −1 cm-1, enabling these ceramics to be suitable for electric discharge machining.
Nonstoichiometric Composition and Densification of CaRuO3 by SPS
Authors: Keawprak Nittaya , Tu Rong , Goto Takashi
Published: March 2009

Calcium ruthenates were prepared in different ratios of Ru to Ca (RRu/Ca = 0.5～1.4) by spark plasma sintering. CaRuO3 in a single phase was obtained at RRu/Ca = 1.0. At RRu/Ca < 1.0, a mixture of CaRuO3 and CaO was obtained, whereas CaRuO3 with second phase of RuO2 was obtained at RRu/Ca > 1.0. The density at RRu/Ca < 1.0 were 80-85% and slightly increased with increasing RRu/Ca. The density significantly increased up to 95% with increasing RRu/Ca from 1.1 to 1.4, suggesting that the second phase of RuO2 was effective to densify CaRuO3. The density of CaRuO3 in a single phase was 82% at most. The lattice parameters of CaRuO3 decreased with increasing RRu/Ca from 0.7 to 1.0, showing a nonstoichiometric range of Ca1+δRuO3+δ.
Iterative Algorithm for Structure Reliability Analysis Based on Support Vector Classification Method
Authors: Ma Chao , Lu Zhen Zhou
Published: March 2009

For reliability analysis of structure with implicit limit state function, an iterative algorithm
is presented on the basis of support vector classification machine. In the present method, the support
vector classification machine is employed to construct surrogate of the implicit limit state function.
By use of the proposed rational iteration and sampling procedure, the constructed support vector
classification machine can converge to the actual limit state function at the important region, which
contributes to the failure probability significantly. Then the precision of the reliability analysis is
improved. The implementation of the presented method is given in detail, and the feasibility and the
efficiency are demonstrated by the illustrations.
Contact Damage and Strength Degradation in Nitrided Pressureless Sintered (NPS) Silicon Nitrided Ceramics
Authors: Kang Chang Gyu , Kim Chul , Kim Tae Woo , Han In Sub , Lee Kee Sung
Published: March 2009

A study is made of the damage resistance and strength degradation of nitrided pressureless
sintered (NPS) silicon nitride ceramics. The silicon nitride is prepared by cost-effective NPS process
combining by nitridation and consecutive pressureless sintering. Contact testing with spherical
indenters is used to characterize the damage response. Examination of the indentation sites indicates a
quasi-plastic damage modes are observed. Bend tests on specimens containing quasi-plastic contact
damages reveal those materials to be not susceptible to strength degradation.
Predictive Model Based on Genetic Algorithm-Neural Network for Fatigue Performances of Pre-Corroded Aluminum Alloys
Authors: Fan Chao Hua , He Yu Ting , Zhang Heng Xi , Li Hong Peng , Li Feng
Published: March 2009

In the paper, genetic algorithm is introduced in the study of network authority values of BP
neural network, and a GA-NN algorithm is established. Based on this genetic algorithm-neural
network method, a predictive model for fatigue performances of the pre-corroded aluminum alloys
under a varied corrosion environmental spectrum was developed by means of training from the testing
dada, and the fatigue performances of pre-corroded aluminum alloys can be predicted. The results
indicate that genetic algorithm-neural network algorithm can be employed to predict the underlying
fatigue performances of the pre-corroded aluminum alloy precisely, compared with traditional neural
network.
Numerical Simulation of Pressure Grouting in Soil Nail Pull-Out Tests
Authors: Su Li Jun , Yin Jian Hua , Wang Shan Yong , Liao Hong Jian
Published: March 2009

Soil nailing is a widely used technique for stabilizing slopes and excavations. In all current
design methods, the nail-soil interface shear strength, that is, the pull-out resistance of a soil nail is an
important parameter which controls the design and safety assessment of the soil nailing system. The
pressure grouting is a cost effective method for increasing the soil nail pull-out resistance and in turn
improving the performance of the nailed structure. In this paper, a three dimensional (3-D) finite
element (FE) model for pull-out tests is established and verified by comparing simulated results with
measured data. This model is then used to simulate the effect of grouting pressure on the soil nail
pull-out resistance.
Determination of Growing Direction of Fatigue Crack
Authors: Dai Yao , Tan Wei , Sun Chang Qing , He Jia Wen
Published: March 2009

The stress field of an interfacial crack in non-homogeneous materials is computed using
the semi-analytical method of arbitrary lines (MAL). Then, the eigen-functions of stress, strain and
displacement, i.e. the angular distribution functions near a crack tip, are analyzed based on our
wedge-shape non-homogeneous model. Finally, the growing direction of the interfacial crack is
determined according to the relevant maximum normal stress criterion accurately. Therefore, the
effective approach is provided for solving the complicated crack growing directions of an interfacial
crack in non-homogeneous materials.