bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamic Crack Analysis in Functionally Graded Piezoelectric Solids by Meshless Local Petrov-Galerkin Method
Authors: Sladek Jan , Sladek Vladimir , Zhang Chuan Zeng
Published: March 2009

In the present paper, the meshless local Petrov-Galerkin (MLPG) method is extended to
two-dimensional (2-D) continuously nonhomogeneous piezoelectric solids with cracks under
dynamic loading conditions. To eliminate the time-dependence, the Laplace-transform technique is
applied to the governing partial differential equations which are satisfied in the Laplace-transformed
domain in a weak-form on small fictitious subdomains. A meshless approximation is used for
spatial variations of the displacements and the electric potential.
Assessment of the Fatigue Behaviour of Friction Stir Welded Joints: Aluminium Alloy 6082-T6
Authors: Moreira Pedro Miguel Guimarães Pires , de Jesus A.M.P. , Ribeiro A.S. , de Castro Paulo Manuel Salgado Tavares
Published: March 2009

A study on the fatigue behaviour of friction stir butt welds of 3mm thick 6082-T6
aluminium alloy was carried out. Monotonic tensile and cyclic tests of welded joints and base
material were performed to understand the influence of the welding process on the static and fatigue
properties. Microhardness profiles were measured and fatigue crack growth curves were determined
for cracks growing in different locations of the weldments. Friction stir material exhibited lower
strength and ductility properties than the base material. However, an enhanced crack propagation
resistance is observed.
Eurocode 3’s Standard Curves and Theory of Critical Distances to Estimate Fatigue Lifetime of Steel Weldments
Authors: Susmel Luca
Published: March 2009

This paper reports on the use of the Modified Wöhler Curve Method (MWCM) applied
along with the Theory of Critical Distances (TCD) to estimate fatigue lifetime of steel welded joints
subjected to both uniaxial and multiaxial cyclic loading. In a recent work [1] we have proved that
the above engineering method is highly accurate when calibrated by using standard fatigue curves
characterised by a probability of survival equal to 50%. In order to better check its accuracy and
reliability, in the present study our approach is systematically applied to a large amount of
experimental data by calibrating it using standard fatigue curves having a probability of survival
equal to 97.7%. This exercise allowed us to prove that the in-field application of such an
engineering procedure results in estimates which fully comply, from a statistical point of view, with
Eurocode 3’s recommendations. This result strongly supports the idea that our approach can safely
be employed to perform the fatigue assessment of real mechanical assemblies, with the advantage
over other existing methods that fatigue lifetime under any kind of fatigue loading can be estimated
by simply post-processing linear-elastic Finite Element Models.
Fatigue Analysis of Notched Shafts under Multiaxial Synchronous Cyclic Loading
Authors: Pitatzis N. , Savaidis G. , Savaidis A. , Zhang Chuan Zeng
Published: March 2009

Parametrical elastic-plastic finite element analyses of a circumferentially notched shaft
subjected to multiaxial synchronous fatigue loading are performed considering two load
combinations: (1) constant tension with cyclic torsion and (2) constant torsion with cyclic tensioncompression.
The load amplitudes and the mean loads are varied to investigate their influences on
the local stress-strain responses. The Multilayer Plasticity Model of Besseling in conjunction with
the von Mises yield criterion is applied to describe the elastic-plastic material behavior. Coarse and
fine meshes as well as three different types of multilinear approximations (twenty-, five- and threesegments)
of the material stress-strain curve are used. Numerical results are presented to reveal the
mutual interactions between the applied normal and torsional loads and the stress-strain response at
the notch-root.
Fatigue Life of Multi-Spot Welded Structures
Authors: Salvini Pietro , Vivio Francesco , Vullo Vincenzo
Published: March 2009

A procedure that makes use of a conventional stress value (ERS) is applied to spot
welded joints. The ERS can be evaluated for every spot weld of the structural model. Through the
use of ERS-N curves, fatigue data performed on different joint geometries can be successfully
mixed together. One of the main aspects is that progressive damage deeply influences fatigue
behaviour, so that a simple numerical solution neglecting accumulated damage is unable to foresee
the whole fatigue life. In the present paper the method has been applied to many experimental
results: it is shown that a unique criterion is able to deal with several different structures and
materials.
Behavior of Microbiological Influenced Corrosion of the Ship Plate Steel in Marine Environment
Authors: Li Qing Fen , Li Chun Hui , Long Ping , Xue Li Li
Published: March 2009

The microbiological influenced corrosion (MIC) behaviors of the ship plate steel directly
exposed in different medias (the sterile seawater, the ferrous bacteria solution and the
sulfate-reducing bacteria solution) were investigated with electrochemical impedance spectroscopy
(EIS), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and scanning electron
microscopy (SEM). Corrosion potential, electrochemical impedance and micrographs of specimens
under different experimental conditions were obtained. Results show that the FB and SRB in the
marine environment affect the corrosion behavior of the ship plate steel greatly. The corrosion
process in FB and SRB environment was controlled by both bacteria and corrosion products. The
mechanism of MIC is discussed.
Fatigue Crack Propagation in Friction Stir Welded Joints of Particulate Metal-Matrix Composite
Authors: Pirondi Alessandro , Collini Luca , Fersini D.
Published: March 2009

In this work the fatigue crack growth properties of friction stir welded butt joints are
evaluated. Fatigue Crack Growth (FCG) tests have been carried out on two particle-reinforced
aluminium alloys (AA6061/Al2O3/20p and AA7005/Al2O3/10p). FCG properties have been
evaluated at the centre and at the side of the weld, respectively. The results are compared with FCG
properties of base materials. The role of alumina in particles inside the matrix is evident in the
threshold region: this can be explained in terms of Roughness Induced Crack Closure.
The Inelastic Response Differences of Two Buildings Designed without and with Steel Braces
Authors: Avila Jorge A. , Angeles Alejandro
Published: March 2009

The inelastic behavior of a 17 level reinforced concrete building, for two structural
models, is studied: reinforced concrete frames only (A case), and reinforced concrete frames, and
K-type steel braces (B case). The building is designed to avoid that the drifts exceed 0.012 for the
same seismic behavior factor level (Q= 3), in agreement with the Mexico City Code. The building is
type B (offices). The soil is considered as soft and the foundation is a rigid box with point piles.
With the design, A and B cases, the comparisons of the transversal sections, maximum lateral
displacements, drifts, story shears, design mechanical elements and resultant reinforcement steel are
made. With the step-by-step analysis, A and B cases, with representative accelerations records of the
soft soil, the inelastic responses of the local and global ductility demands are determined and also
are compared with the permissible levels of the Code. We pretend to observe the inelastic behavior
(displacements, maxima demands of global and local ductility), for both types structural models, to
decide which it is more convenient.
The Response Probability of Mesoscopic Damage in Sandstone to External Force and Temperature
Authors: Xi Dao Ying , Xu Song Lin , Du Yun , Li Ting , Wan Xin Lin
Published: March 2009

The rock is assumed to be assembled by a great number of HMUs. The number of HMUs
responding to external force is uncertain, which leads to the instability of hysteretic loops.
Transition probability of HMUs to the external force and temperature varies with external loading
frequency and temperature. The self-adaptive adjustment effects for rocks in frequency field are
obtained by uniaxial and triaxial cyclic loading: when frequency increases, transition probability of
the response of mesoscopic structure to applied loads reduces, the adjustment time of self-adaptive
process becomes shorter, residual strain become smaller, and hysteretic loops tend to be easy to be
stable. The self-adaptive adjustment effects in temperature field can also be obtained.
Impact of Prior Loading on the Reliability of Safety Critical Systems
Authors: Smith David John
Published: March 2009

Probabilistic models are developed to determine changes in the survival probability
particularly when prior loading contributes to changes in residual stress and fracture toughness.
Experimental evidence for variations in toughness and residual stress is examined and then
incorporated into probabilistic models. The structure’s reliability is consistently better after prior
loading.
Analysis of Thin Film Cracking and Buckling on Compliant Substrate by Fragmentation Test
Authors: Andersons Janis , Tarasovs S. , Leterrier Yves
Published: March 2009

Application of coating fragmentation test for determination of coating properties is
considered. A probabilistic model of coating fragmentation under uniaxial tensile loading is applied
for coating and interface property identification of thin brittle coating/polymer substrate system. A
finite element model is developed to simulate the process of buckle formation in coating strips
during fragmentation test. The measured buckle geometry parameters and buckle density evolution
as a function of the applied strain is used to estimate the interface toughness.
Study on Propagation Rules of a Close Crack in Rockmass
Authors: Zhang Guang , Chen Jing Xi , Li Yage , Mao Ling Li
Published: March 2009

In this paper, supposing the rockmass is an idealistic elastic object, the methods to
calculate I type and II type strength factors of the crack tip are obtained by analyzing the stress state
of the inner surface of a close crack in rockmass under compressive and shear stress and applying
complex variable function stress method and superposition principle. Furthermore, supposing the
friction coefficient, f , of the crack surface is a constant and the normal pressure, P(x) , on the
crack surface obeys to normal distribution, the propagation rules of a close crack under compressive
and shear stress are also deduced.
Concrete Damage Parameter and its Size Effect
Authors: Wang Xiang Dong , Zhu Wei Xuan , Deng Ai Min , Zhou Dong , Xu Dao Yuan
Published: March 2009

Damage parameter of concrete is widely used in design and construction of concrete
structures. An experimentation method has been designed, which can simulate the initial damage by
mixed initiator into concrete. Damage parameter can be obtained in laboratory with standard
specimens. But practical structure is very large. It is not rational to use this parameter in practical
structures. So size effect on damage parameter is studied. It is concluded that initial damage and
summit damage grow with the increase of structure size, but the growth rate becomes gentle with
size increasing. When the size is larger than 500 mm×500 mm, the growth rate is less than 15‰, so
the results obtained from specimen in 500 mm×500 mm can be used for mass concrete structures.
Effect of Triaxiality on Damage Parameters in Adhesive
Authors: Hilmy I. , Abdel Wahab M.M. , Crocombe A.D. , Ashcroft Ian A. , Solana A.G.
Published: March 2009

Adhesive in joints will have complex stress state rather than bulk adhesives. This will lead to the
assumption behind bulk adhesive that triaxiality function (Rv) is equal to one (uni-axial stress state)
is not valid anymore. In this paper, new procedure to find damage parameters α and β for single-lap
joints has been developed based on global damage of adhesive joints. With this procedure, damage
parameters α and β have been found. Validating the procedure by calculating the number of cycles
to failure (Nf) has been performed successfully. The accuracy of the damage evolution equation is
less than 2 %.
Prediction of Welding Distortions of Stainless Steel Ship
Authors: Li Hong , Ren Hui Long
Published: March 2009

The long-term goal of prediction of welding distortions in ship sections is to specify an
optimal welding procedure to minimize distortions due to welding. The equivalent load method
based on inherent strain for material of stainless steel is studied in this paper. A fillet welding
experiment followed by infrared thermograph is done. Then simplified elastic plastic analysis
model is used while combining the inherent strain theory and the experimental results for accurate
and efficient analysis. The results of temperature field in FEM have been supported by the
experimental data. Furthermore, the distortions of the stainless steel ship structure are calculated by
FE analysis.
The Brittle Fracture of Polycrystalline Zinc
Authors: Hughes Gareth M. , Smith Gillian E. , Flewitt Peter E.J. , Crocker A.G.
Published: March 2009

In polycrystalline materials grain boundaries provide an important contribution to the resistance
to the propagation of both brittle and ductile cracks. In this paper we describe experimental measurements
of brittle cracks developed within both small punch and matchstick test specimens of polycrystalline hcp
zinc. These specimens were tested over the temperature range 77 to 423K. Fractography undertaken using
focussed ion beam imaging provides detail of the propagation from grain to grain and across {10-12}
twins of (0001) basal and {10-10} prismatic cleavage cracks. The results are discussed by comparison
with the predictions from previously described 3-D geometric modelling applied to this hcp polycrystalline
material.
Prediction of the Elastic Modulus of Cement Paste as a Kinetic Hydration Model
Authors: Park Ki Bong , Lee Han Seung , Wang Xiao Yong , Lim Seung Min
Published: March 2009

This paper describes a numerical method for estimating the elastic modulus of cement
paste. The cement paste is modeled as a unit cell, which consists of three parts: dehydrated cement
grain, gel, and capillary pore. In the unit cell, the volume fractions of the constituents are quantified
with a single kinetic function of the degree of hydration. The elastic modulus of cement paste was
calculated from the total displacement of constituents when the uniform pressure was applied to the
gel contact area in cement paste assumed a homogenous isotropic matrix. Numerical simulations
were conducted through the finite element analysis of the three-dimensional periodic unit cell. The
model predictions were compared with experimental results. The predicted trends agree with
experimental observations. The approach and some of the results might also be relevant for other
technical applications.
Fatigue Design of Welded Joints by Local Approaches: Comparison between Fictitious Notch Rounding and Strain Energy Averaging
Authors: Lazzarin Paolo , Berto Filippo , Radaj D.
Published: March 2009

The paper demonstrates the close correspondence between two local approaches to assess the fatigue strength
of welded joints: Radaj’s approach based on fictitious notch rounding and a recently proposed approach based on the
local strain energy density (SED) averaged over a given control volume. This volume surrounds the weld root or weld
toe, both modelled as sharp (zero radius) V-notches with different opening angles. The two approaches are applied to
load carrying and non-load carrying cruciform joints and the theoretical fatigue notch factors Kf are compared. The
SED averaged over the control volume is determined from finite element models with very fine meshes, as typically
designed to evaluate the intensity of the asymptotic stress distributions, and also from coarse meshes, showing a
surprisingly good correspondence.
Automatic 3-D Crack Propagation Calculations in Industrial Components: A Pure Hexahedral versus a Combined Hexahedral-Tetrahedral Approach
Authors: Dhondt Guido
Published: March 2009

In recent years, increased loading and low weight requirements have led to the need for
automatic crack tracing software. At MTU a purely hexahedral code has been developed in the
nineties for Mode-I applications. It has been used extensively for all kinds of components and has
proven to be very flexible and reliable. Nevertheless, in transition regions between complex components
curved cracks have been observed, necessitating the development of mixed-mode software.
Due to the curvature of the crack faces, purely hexahedral meshes are not feasible, and therefore a
mixture of hexahedral elements at the crack tip, combined with tetrahedral in the remaining structure
has been selected. The intention of the present paper is to compare both methods and to point
out the strength and weaknesses of each regarding accuracy, complexity, flexibility and computing
time. Furthermore, difficulties arising from the out-of-plane growth of the crack such as the determination
of the crack propagation direction are discussed.
A Study on the Development Mechanism of Early Strength in Cement Mortar Using an Early-Strength Polycarboxylated Agent
Authors: Park Won Jun , Lee Han Seung , Park Ki Bong
Published: March 2009

It is well known that PC (polycarboxylate) agent is superior to other agents for the
early-strength of concrete. Thus, this study investigates the development of mortar strength using
various agents. To prove this, various factors were tested. Furthermore, this study measured
compressive strength at the age of 18, 24, 36, 72, and 168 hours and gave a request text TG/DTA to
observe minute structures. In addition, this study took pictures of minute structures using an SEM
for each agent at the same age. According to the results, mortar using an early-strength PC agents is
faster than a general water reducing AE agent, high performance PC agents, and other agents in the
acceleration of hydration at the same early age. A TG/DTA test shows that the early-strength PC
agents create more hydration products, such as Ca(OH)2, than others at the same age. The degree of
pH in each agent is unrelated to the degree of hydration in mortar. An MIP analysis confirms these
results. However, other methods are required the exact analysis of micro structures.
Study on an FEM Analysis to Evaluate Restrain-Performance of Surface-Finishes for Carbonation
Authors: Lee Sang Hyun , Lee Han Seung , Park Ki Bong
Published: March 2009

Recently, Reinforced Concrete(RC) is used in most buildings. However, steel bars in
concrete cause corrosion through carbonation. Furthermore, corrosion shortens the life span of RC
structures. Therefore, the surface-finishes such as restraint for penetration and diffusion of CO2
were used to lengthen the life span of RC structures. This study attempted to verify the restraining
effect on a carbonation job according to the applied surface-finishes using an FEM analysis. This
study also evaluated the restraining effect of carbonation on other surface-finishes with the process
proposed in this study.
Two-Parameter Criteria for Ductile Crack Initiation and Propagation in High-Grade Line Pipes
Authors: Kayamori Yoichi , Crofton P.S.J. , Smith Roderick A.
Published: March 2009

Full-scale burst test data of high-grade line pipes for high-pressure gas pipelines were
referred to, and 3-D elastic-plastic finite element analysis was carried out using the test data for the
calculation of fracture parameters. Ductile crack initiation was evaluated by the intersection of a
toughness locus and a crack driving force curve, where the toughness locus was indicated by the
relationship between the critical equivalent plastic strain and the stress triaxiality, and the crack
driving force curve was shown by a history of the equivalent plastic strain and the stress triaxiality at
characteristic distance. In addition, ductile crack rapid propagation was assessed by the relationship
between the critical CTOA and the global constraint factor, where the critical CTOA remained almost
constant because of high constraint.
A Numerical Method for Predicting the Chloride Diffusivity of Concrete with Interfacial Cracks
Authors: Zheng Jian Jun , Pu Jun Ping , Mao Ke Feng
Published: March 2009

Due to its importance to the durability assessment of reinforced concrete structures
located in a marine or de-icing salt environment, it is essential to determine the chloride diffusivity
of concrete. This paper presents a numerical method for predicting the chloride diffusivity of
concrete with interfacial cracks. By modeling concrete as a three-phase composite material
composed of aggregate, interfacial transition zone and cement paste, a composite circle model with
an interfacial crack located on the aggregate surface is constructed. The finite element method is
used to solve the composite circle under a given boundary condition and the chloride diffusivity of
concrete is then determined numerically. After verifying the numerical method with experimental
results obtained from the literature, the effect of interfacial cracks on the chloride diffusivity of
concrete is evaluated in a quantitative manner. It is found that the chloride diffusivity of concrete
increases with the increase of the subtended angle of interfacial cracks. The paper concludes that the
numerical method presented in this paper can predict the chloride diffusivity of concrete with
reasonable accuracy.
Interaction of Circular Lining and Interior Linear Crack by Incident SH-Wave
Authors: Li Hong Liang , Han Guang Cai , Li Hong
Published: March 2009

In this paper, the method of Green’s function is used to investigate the problem of
dynamic stress concentration of circular lining and interior linear crack impacted by incident
SH-wave. The train of thought for this problem is that: Firstly, a Green’s function is constructed for
the problem, which is a fundamental solution of displacement field for an elastic space possessing a
circular lining while bearing out-of-plane harmonic line source force at any point in the lining. In
terms of the solution of SH-wave’s scattering by an elastic space with a circular lining, anti-plane
stresses which are the same in quantity but opposite in direction to those mentioned before, are
loaded at the region where the crack existent actually, we called this process “crack-division”.
Finally, the expressions of the displacement and stress are given when the lining and the crack exist
at the same time. Then, by using the expressions, some example is provided to show the effect of
crack on the dynamic stress concentration around circular lining.
Fatigue Crack Growth Resistance in Ni-Base Super Alloy
Authors: Morino Kazuhiro , Kawagoishi Norio , Chen Q. , Matsuyama Y. , Nakamura Y.
Published: March 2009

Rotating bending fatigue tests were carried out to investigate the influence of grain size
on the resistance to crack growth of Ni-base super alloy, Inconel 718, using the materials with grain
sizes of about 20, 50,100 and 200 たm, at room temperature. The larger grain size, the smaller crack
growth rate, though the static strength was decreased with increase in grain size. The growth rate of
a small crack was uniquely determined by the term ja
na (Small crack growth law), where ja and a
are the stress amplitude and the crack length, respectively, and n is a constant. The resistance to
crack growth among materials was evaluated based on the law and showed a good correlation with
tensile strength jB, meaning that fatigue life can be predicted by using only j B BB.
Finite Element Analysis of a Composite Bulkhead Structure
Authors: Apicella A. , Armentani Enrico , Esposito Renato , Pirozzi Michele
Published: March 2009

Reducing structural weight is one of the major ways to improve aircraft performance.
Lighter and/or stronger materials allow greater range and speed and may also contribute to reducing
operational costs. Nowadays composite materials are widely used in “primary” structural
components such as fuselage, for which contrasting requirements like lightness and structural
strength are required, so particular attention is necessary during its design. In this paper a composite
front bulkhead, subjected to ultimate pressure load, was examined. The front bulkhead is made of a
composite skin, stiffened with seven vertical stiffeners linked through metallic fittings; the whole
system is joined to the fuselage by rivets. A Finite Element model was established: the used
elements were four nodes shells, simulating composite layers, and two nodes bar elements,
simulating rivets; the structure was clamped and a pressure load was applied to the skin. A linear
static stress analysis was performed to calculate strains in particular points in which strain gauges or
rosettes are placed: the numerical results, compared with experimental ones, show a good degree of
correlation. Stress calculations were performed in order to verify the front and rear bulkhead
structural safety.
Optimising Weld Process Conditions for Enhanced Fatigue Performance
Authors: James M. Neil , Lombard Hannalie , Hattingh D.G. , Steuwer Axel
Published: March 2009

This paper presents some ideas on incorporating output from advanced synchrotron and
neutron scanning strain methods in improved assessment of the influence of weld process
parameters on residual strains at welds and on their fatigue performance. It very briefly outlines two
different cases involving synchrotron diffraction strain scanning of friction stir welds in a strain
hardened aluminium alloy and neutron diffraction strain scanning of MIG welds in high strength
steel.
Advanced Local Concepts for Assessing the Fatigue Durability of Welded Joints
Authors: Sonsino C.M. , Radaj D. , Fricke W.
Published: March 2009

Some recently developed variants of local concepts for assessing the fatigue strength and
structural durability of welded joints are reviewed. These comprise structural stress, notch stress or
strain and fracture mechanics concepts. New variants of the structural stress concept are Dong’s
gradient stress approach and Xiao-Yamada’s ‘one millimetre stress’ approach. FE meshing rules
have been developed for welded joints in thin sheet structures. The concept of fictitious notch
rounding is now better substantiated for aluminium alloys. The small-size notch concept is
applicable to thin sheet lap joints. The new notch stress intensity factor concept is based on the
singular stresses at the sharp weld toe notch. Advanced fracture mechanics concepts combine crack
initiation at the seam weld root or nugget edge and crack propagation over the plate thickness
resulting in endurable FK values as function of cycles per unit thickness, N/t.
Research on Standard of Acceptable Risk for High Arch Dam in Developing Countries
Authors: Chen Zai Tie , Ren Qing Wen
Published: March 2009

It is proposed to make use of dam risk rate, economic loss risk value and life loss risk
value in evaluating the risk of high arch dam. The acceptable standards of risk for high arch dam in
the developing country should not be set too high,it should reflect the level of economic and
technology development, the policy for energy sources,the life value as well as the degree of the
importance attached. Based on study of the characteristics of high arch dam and by means of the
comparison of the levels of economic development, the life values and the degrees of the
importance attached between developing and developed countries, as well as the analogy analysis of
rare risk events occurring in developing countries, the reference value of the single high arch dam
acceptable risk rate, economic loss risk and life loss risk in developing countries are found to be
10 /(yr dam) 6 ⋅ − , 10000$/(yr ⋅ dam) and 0.001person/(yr ⋅ dam) respectively;a method is worked out for
determining the acceptable risk rate,the acceptable economic loss risk value and life loss risk value.
Numerical Analysis of the Crack Growth in a High Loaded Bolt Connection
Authors: Knez Marko , Glodež Srečko , Kramberger Janez
Published: March 2009

The present paper deals with the research on the crack growth in a bolt connection of a
lug for crane counter weight bars. Counter weight bars are structural elements that are subjected to
very heavy loads and therefore special attention must be paid. The main purpose of this research is
to determine the number of the load cycles required for a crack to propagate from initial to critical
crack length, when the final failure can be expected to occur. All required material parameters and
the experimental results were determined in our previous research.
The influence of the initial crack size upon the remaining life of the lug is researched
numerically by means of finite element analysis and analytically by use of the corrected analytical
model.
Fatigue and Tensile Properties of Pallets Made from Waste Plastics
Authors: Takeda K. , Hiraba T. , Ebara Ryuichiro , Shinagawa Kazunari , Hirai M. , Nonomura T. , Morimoto I.
Published: March 2009

Fattiigue and ttensiille properttiies of speciimens cutt from palllletts made from wastte pllasttiics by
usiing of newlly develloped recyclliing apparattus are presentted.. Testted matteriialls are pollypropyllene
fiillm,, pollypropyllene pelllletts,, pollyetthyllene,, pollyetthyllene-20wtt%flly ash composiitte and pollyetthyllene
-20wtt% callciium carbonatte composiitte.. Itt can be conclluded tthatt tthe newlly develloped recyclliing
apparattus make possiiblle tto proviide palllletts made from wastte pollypropyllene and pollyetthyllene wiitth
ullttiimatte ttensiille sttrengtths of more tthan niinetty percentt of tthose made from fresh pollypropyllene and
pollyetthyllene.. Itt has become cllear tthatt carefull ttreattmentt of composiitte process for wastte pllasttiics
enablle tto iimprove fattiigue sttrengtth of pollyetthyllene composiittes by sttrengttheniing tthe iintterface
bettween an addiittiive and base matteriiall..
Numerical Modelling of Concrete Beams Reinforced with Pre-Stressed CFRP
Authors: Alfaiate Jorge , Domingues Thiago
Published: March 2009

In this paper, a numerical simulation is presented on the behavior of concrete beams,
reinforced with pre-stressed CFRP. The numerical results are compared to experimental results.
Non-linear material behaviour is considered, namely: the inelastic compressive concrete behaviour,
the elasto-plastic behaviour of steel reinforced bars, the bond-slip relationship between the concrete
and the internal steel reinforced bars, the mode-II fracture interface between the concrete and the
pre-stressed CFRP and concrete cracking. Cracking in concrete is modelled according to a discrete
strong discontinuity approach, in which the discontinuities are embedded within the finite elements.
A sequentially-linear approach is adopted in order to avoid non-convergence problems. The present
analysis aims at trying to better understand the failure mechanisms found in the experimental tests;
these mechanisms will be discussed in a final section of the paper.
Evaluation of Fatigue Strength of Welded Joints by Local Strain Measurements at Weld Toe
Authors: Casavola C. , Pappalettere C.
Published: March 2009

The fatigue strength of real welded structures neither can be covered by formulae or
theoretical arguments, nor simply deducted by studying a complex assembly through its elementary
components because of the many interactions among different factors governing the phenomenon.
In view of this, the support of experimental observations and practical procedures to evaluate the
stress/strain magnitude that could lead some components to unsafe working conditions should be
preferred, especially in industrial applications where fast and reliable responses are strongly needed.
Simulation of Failure in Hydrating Cement Particles Systems
Authors: Tan Li Kun , Schlangen Erik , Ye Guang
Published: March 2009

The aim of this paper is to present the failure process of cement paste at different ages
subjected to tensile loading. The input structure (cement paste) is generated by means of the cement
hydration model HYMOSTRUC3D. A 2D-slice of this generated microstructure is subsequently
transferred to the Delft Lattice Model, in which the failure process is analysed. Failure of cement paste
microstructures at different degree of hydration, various water-cement ratios and different particle
size distributions are analysed and discussed in the paper.
Parametric Variational Principle for Solving Coupled Damage Problem
Authors: Hua Yuan , Lv Bao Hua , Zhou Tai Quan
Published: March 2009

The parametric variational principle adopts the extreme variational idea in the modern
control theory and uses state equations deduced from the constitutive law to control the functional
variation, which is an effective solution to the nonlinear equations. Based on the fundamental
equations of elasto-plasticity coupled damage problem, the potential functional of elasto-plasticity
is constructed. Also the state equations with approximation of damage evolution equation and load
functions are constructed in the paper. The solution of elasto-plasticity damage problem can be
deduced to solve problem of the minimum potential energy function under the restriction of state
equations. Thus the parametric variational principle for coupled damage is proposed. The
variational principle has the virtue of definite physical meaning and the finite element equations are
presented in the article to facilitate the application of parametric variatioal principle, which is easy
to program on computer. Using the method mentioned in the article, a numerical calculation is
carried out and the calculation result shows that the method is efficient for solving elasto-plasticity
damage problem.
An R-Curve Approach for Fracture of Ultra High Performance Cementitious Composites
Authors: Wu Xiang Guo , Han Sang Mook , Kim Sung Wook , Kang Su Tae
Published: March 2009

An R-curve formula for ultra high performance cementitious composites is derived in this
paper. The fracture mechanics based on R-curve is used to predict the load-deflection relation of
ultra high performance cementitious composites. The reductions of stress intensity factor and
CTOD by steel fiber reinforcement are assumed as conforming linear distribution along crack
propagation. The effective numbers of steel fiber on unit area based uniform distribution is used
here. Results of the theoretical predictions show a good agreement with test results of three point
bending beam of UHPCC. The modified R-curve formula for UHPCC can be a reference for future
study of fracture performances of UHPCC.
Direct Tensile Performance of UHPCC Element Based on Damage Mechanics
Authors: Han Sang Mook , Wu Xiang Guo , Kim Sung Wook , Kang Su Tae
Published: March 2009

Direct uniaxial tension test of ultra high performance cementitious composites I shape
specimens have been investigated in this paper. A nonlinear analytical model based on continuum
damage mechanics is developed to characterize tensile stress-strain constitutive response of UHPCC.
Basic governing equations of damage evolution and material constitutive relation are established
considering random damage which conforms to a modified Weibull type distribution proposed in
this paper. Calculation suggests that Weibull distribution can describe damage evolution of UHPCC
and predict the constitutive relation and damage evolution equation.
Damage Constitutive Relationship of SRC Member Nonlinear Analysis
Authors: Zheng Shan Suo , Che Shun Li , Li Lei , Zhang Liang , Zhao Qin
Published: March 2009

The damage constitutive relationship is a key problem to nonlinear analysis of structural
members. It is much more necessary to study systematically related damage constitutive relationship
of steel reinforced concrete (SRC) members because of their peculiarity. Based on the experimental
phenomena analysis and damage theory, the mesoscopic failure mechanism of concrete as well as the
interface of shaped steel and concrete is analyzed. At the same time, their mesoscopic damage models
and corresponding assumptions of the models are established by considering material failure
characteristics. Subsequently, the mechanism of the models is analyzed, which indicates that they fit
to simulate failure process of the materials. According to the models, the related damage constitutive
relationship for SRC members is deduced by principle of energy and force balance. Combined with
corresponding experimental study, it is shown that the constitutive relationship presented is
reasonable and practicable, so it facilitates SRC member nonlinear analysis.
Scattering of SH Wave by an Interacting Mode III Crack and a Circular Cavity in Half Space
Authors: Yang Zai Lin , Chen Zhi Gang , Liu Dian Kui
Published: March 2009

Scattering of SH wave by an elastic half space with a circular cavity and a crack in any
position and direction is studied with Green’s function, complex function and multi-polar
coordinate method. First, a suitable Green’s function is constructed, which is the fundamental
solution of the displacement field for a half space with a circular cavity impacted by an out-plane
harmonic line source loading at an arbitrary point in half space. Then a crack in any position and
direction is constructed by means of crack-division in half space. Finally the displacement field and
stress field are established in the case of coexistence of circular cavity and crack, and the expression
of dynamic stress intensity factor (DSIF) at the tip of crack is given. According to numerical
examples, the influences of different parameters on DSIF are discussed.
Damage Behavior of Steel Fiber Reinforced and Polymer Modified Concrete under Impact Loading
Authors: Liu Yi Ping , Tang Li Qun , Huang Xiao Qing
Published: March 2009

Damage behaviors of plain concrete (PC), steel fiber reinforced concrete (SFRC), steel
fiber reinforced and polymer modified concrete (SFRPMC) are studied in this paper by use of a
Split Hopkinson Pressure Bar (SHPB). Three kinds of concrete materials appear obvious strain rate
strengthening effects. SFRPMC appears a better resistance and energy absorption ability. A
rate-dependent damage model is suggested to depict the impact damage evolution of three kinds of
materials under different impact velocities. The simulation results showed the theoretical model
could well describe the dynamic behaviors of the three kinds of materials, and steel fibers attribute
more to resist crack develop in early stage, “bridge effect” of steel fibers slow up the damage
evolution in SFRC, with the addition of polymer, the internal structures of SFRPMC were modified,
SFRPMC gains better ductility, and appears a kind of “softening effect”, which makes the damage
in SFRPMC develop more slowly than that in PC and SFRC under impact loading.
An Open Crack Model for Vibration Simulation of Beam Structures by Transfer Matrix Method
Authors: Wang Ke Ming , Xiang Song
Published: March 2009

Crack detection of critical beam structures such as bridges and aircraft wings by vibration
monitoring is based on understanding how a crack affects the vibration characteristics of a beam
structure. Transfer matrix method is a convenient, effective, and hence widely used approach to
beam vibration analysis, but a crack in the beam makes this method ineffective. This paper proposes
an open crack model that simulates the local stiffness reduction effect of a transverse crack by a
rectangular slot to make the transfer matrix method able to analyze vibrations of a cracked beam.
The depth of the slot is identical to the depth of the crack, and the equivalent width of the slot is
obtained by comparison of stiffness reductions of finite element analysis results and the counterpart
transfer matrix method results. Different dimensions of rectangular beams, different crack positions
and loading conditions are considered and statistic method is used to improve the generality and
accuracy of the model. A calculation example of a cracked cantilever beam is given and the validity
of the proposed model is verified with available results of existing models.
Effect of Stress Distribution on Fatigue Life of Tubular Joints in Offshore Engineering
Authors: Shao Yong Bo
Published: March 2009

In the assessment of fatigue life of tubular joints in offshore engineering, hot spot stress
range, in conventional method, is frequently used to predict the number of cycles that a tubular joint
can sustain before failure from corresponding S-N curves. This method only considers the effect of
the peak stress at the weld toe on the fatigue life of a tubular joint, but ignores that of the stress
distribution along the weld toe. The effect of the stress distribution along the weld toe on the fatigue
life of tubular joints can be evaluated indirectly by analyzing a fracture mechanics parameter,
namely stress intensity factor. The stress intensity factor values of the surface cracks in the fatigue
failure process for tubular joints subjected to different loading types, thus causing the difference of
the stress distributions along the weld toe, are investigated from both numerical analysis and
experimental measurement. The results show that the stress distribution along the weld toe has
remarkable effect on the fatigue life of tubular joints.
Damage Evaluation of Bone Tissues with Dental Implants
Authors: Lin Daniel , Li Qing , Li Wei , Ichim Ionut , Swain Michael
Published: March 2009

Dental implants have been extensively used in prosthetic dentistry over the last two
decades. Clinical experience shows that the healing and osseointegration process can heavily
influence the success of the implantation. It is critical to understand the damage extent in different
time frames. This paper aims at exploring the mechanical damage of dental implantation over the
healing process. The 3D finite element analysis (FEA) models were developed based on
computerised tomography (CT) scan technology to investigate the load-induced damage of
interfacial osseointegration, as well as cortical and cancellous bone tissues. Unlike the existing
linear finite element (FE) stress analysis, this study takes into account the damage accumulation and
micro-crack nucleation under a framework of bone/interface remodelling. This study reveals the
damage in the surrounding bone tissues and bone-implant interfaces at different stages of the
healing process, and consequently premature load tolerances are suggested.
The Investigations of Fatigue Characteristics of Porous Asphalt with Organomodified Montmorillonite Modified Asphalt
Authors: Wu Shao Peng , Liu Gang , Yu Jian Ying , Cao Ting Wei
Published: March 2009

In this study, organomodified montmorillonite (OMMT) modified asphalt was used in
porous asphalt, and fatigue characteristics of the mixtures with or without OMMT were investigated.
Special attention was paid to the beam specimens aged in a forced draft oven at 60°C for 500h. Basic
fatigue information, such as stiffness, dissipated energy of the material, was obtained through
four-point bending beam testing under different controlled strain. The classical fatigue life definition
was used to evaluate fatigue resistance of different mixtures. The research results indicate that the
OMMT mixture exhibits better fatigue and ageing resistance than the neat one. It is suggested that
OMMT should be an excellent alternative for the durability of porous asphalt.
Shear Debonding of FRP from Concrete: The Influence of FRP Sheet Width on Load Carrying Capacity
Authors: Carloni Christian , Nobile Lucio
Published: March 2009

Carbon fiber reinforced polymer (CFRP) sheets have been extensively used for
strengthening deteriorated concrete structures. The effectiveness of such strengthening depends
upon the load transfer from concrete to the FRP composite. Shear debonding is usually caused by a
crack that forms and then propagates at the interface between the adherents. The influence of the
geometric parameters of the adherents on the fracture propagation is still a subject of research. This
paper presents an experimental investigation performed on direct shear specimens to study the
influence of the relative width of FRP and concrete on the load carrying capacity of the bond and
the stress transfer between the adherents.
Experimental Investigation on Initial Cracking Criterion and Size Effect for I-II Mixed Mode Fracture in Concrete
Authors: Wu Zhi Min , Dong Wei , Yi Fu Min , Yang Shu Tong
Published: March 2009

Most of the previous studies utilized the maximum applied load and the initial crack
length to determine the fracture criterion for Ⅰ-Ⅱ mixed mode fracture of concrete. Actually, the
crack has propagated in the ultimate state due to the semi-brittle behaviors of concrete. Therefore,
adopting the initial fracture toughness as the fracture criterion seems more reasonable. This subject
carried out an experiment of four-point shearing notched beams of concrete with five different
heights, i.e, 200mm, 300mm, 400mm, 500mm and 600mm to determine the initial cracking state
according to sudden decrease of the strain gauges’ values. Then the initial cracking load ini P can be
gained. Besides, the quarter point singular element approach was used to calculate the stress
intensity factors ini
I K and ini
II K corresponding to ini P in the present study. Moreover, different
combinations of ini
I K and ini
II K were obtained according to different positions of pre-cracks.
Correspondingly, the Ⅰ-Ⅱmixed mode fracture initial cracking criterion for concrete can be gained
using the curves of track formed by the different combinations of ini
I K and ini
II K . Through analyzing
the curves of track under different specimen heights, it was found that the size effect exists
significantly in the specimens with heights from 300mm to 500mm, however, the curves in the
500mm and 600mm specimens approach each other.
Experimental Investigation of T-Stress Effects on Photoelastic Fringes in Brazilian Disk under Mode II Conditions
Authors: Guagliano Mario , Ayatollahi Majid R. , Zakeri Mahnaz , Colombo Chiara
Published: March 2009

According to classical definition of crack deformation modes, the constant stress term (Tstress)
exists only in presence of mode I. However, some studies show that this term can exist in
mode II problems as well; and significantly affect the elastic stress field around the crack tip. Based
on the previous analytical results, T-stress changes the photoelastic fringe patterns from symmetric
closed shapes to asymmetric and discontinuous loops. In this research, the effects of T-stress on the
fringe patterns in mode II cracks is investigated experimentally. Test specimens are Brazilian disks
made of polycarbonate, and thermal treatment is performed to remove the residual stresses after
generation of the cracks. Observed isochromatic fringes are in good agreement with theoretical
predictions. Also, experimental results indicate that this specimen contains a negative T-stress in
pure mode II condition.
Determining Interface Strength of Glass-Metal Bi-Layer Laminates Using Cross-Push Method
Authors: Bao Yi Wang , Gao Si Jian , Han Yan Fei , Guan Ming
Published: March 2009

Bond strength of metal-glass bilayer laminate was determined via a simple testing approach using cross-bonded sample and a special fixture. Tensile and shear strength in the interface for glass-metal composite were obtained by this way. It is demonstrated that the strength can be accurately determined when it is lower than the glue strength but it is invalid if the strength is higher than the glue strength. The specimen preparation and testing principle is introduced for determining the interface bonding strength of coatings.