bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental Evidences Concerning Geometrical Accuracy after Unclamping and Trimming Incrementally Formed Components
Authors: Ambrogio Giuseppina , De Napoli L. , Filice Luigino , Muzzupappa M.
Published: March 2009

It is well known that the geometrical accuracy is a very relevant problem in Incremental
Forming operations, since the material is not well sustained and, then, the elastic springback plays a
significant role during the process. A number of researches are involved in the study of geometrical
precision after the forming stage but considering the sheet clamped to the equipment. However, it is
well known that material coupling is carried out after trimming, when it could change its shape after
the new equilibrium. In the paper here addressed the above concept is kept in touch and a wide
experimental campaign has been set-up in order to acquire experimental information on the effect of
unclamping and trimming after incremental forming processes.
The obtained results are able to suggest to the process designer some best practices which are
accurately discussed in the paper.
Incremental Bulging of Sheet Metal Using Water Jet and Shots
Authors: Iseki Hideo , Nara Tomoyuki
Published: March 2009

As a result of the trend of consumer demand for many stamped sheet metal products, the
study of flexible and incremental sheet metal forming and the small-scale production of stamped
goods has received considerable attention. In the previous study, Iseki has developed the
incremental sheet metal bulging method using water jet for the clean forming without the need for
lubricating material. Though he succeeded in shaping wide range of complex shapes of an annealed
aluminum sheet (thickness 0.3 mm, tensile strength 100 MPa ), for example, pyramidal shells,
shells of pyramid frustums, shallow pans and embossed panels, he was completely unsuccessful in
forming shells of a stainless steel sheet (thickness 0.3 mm, tensile strength 640 MPa ). In the
present paper, an incremental bulging method of sheet metal using water jet and shots has been
proposed to form shells of a stainless steel sheet, and the characteristics of deformation, strain
distributions and the forming limit were experimentally studied.
Creating Helical Tool Paths for Single Point Incremental Forming
Authors: Skjoedt M. , Hancock M.H. , Bay N.
Published: March 2009

Single point incremental forming (SPIF) is a relatively new sheet forming process. A
sheet is clamped in a rig and formed incrementally using a rotating single point tool in the form of a
rod with a spherical end. The process is often performed on a CNC milling machine and the tool
movement is programed using CAM software intended for surface milling. Often the function
called profile milling or contour milling is applied. Using this milling function the tool only has a
continuous feed rate in two directions X and Y, which is the plane of the undeformed sheet. The
feed in the vertical Z direction is done in the same angular position in the XY plane along a line
down the side of the work piece. This causes a scarring of the side and also results in a peak in the
axial force when the tool is moved down.
The present paper offers a solution to this problem. A dedicated program uses the coordinates from
the profile milling code and converts them into a helical tool path with continuous feed in all three
directions. Using the helical tool path the scarring is removed, the part is otherwise unchanged and a
major disadvantage of using milling software for SPIF is removed. The solution is demonstrated by
SPIF of three different geometries: a pyramid, a cone and a complex part.
Incremental Forming of Sandwich Panels
Authors: Jackson K.P. , Allwood J.M. , Landert M.
Published: March 2009

This paper presents a first investigation of the applicability of incremental sheet forming
(ISF) to sandwich panels. Two initial tests on various sandwich panel designs established that
sandwich panels which are ductile and incompressible are the most suitable for the process. Further
tests on a sandwich panel with mild steel face plates and a continuous polypropylene core
demonstrated that patterns of deformation and tool forces followed similar trends to a sheet metal. It
is concluded that, where mechanically feasible, ISF can be applied to sandwich panels using
existing knowledge of sheet metals with the expectation of achieving similar economic benefits.
Potentially this will increase the range of applications for which sandwich panels are viable.
Process Characterization of Sheet Metal Spinning by Means of Finite Elements
Authors: Sebastiani Gerd , Brosius Alexander , Homberg Werner , Kleiner Matthias
Published: March 2009

Sheet Metal Spinning is a flexible manufacturing process for axially-symmetric hollow
components. While the process itself is already known for centuries, process planning is still based
on undocumented expertise, thus requiring specialized craftsmen for new process layouts. Current
process descriptions indicate a vast scope of different dynamic influences while the underlying
mechanical model uses a simple static approach. Thus, a 3D Finite Element Model of the process
has been set up at IUL in order to analyze the process in detail, providing online as well as cross
sectional data of the specimen formed. Within the scope of this article, the results of the above
mentioned Finite Element Analysis (FEA) are presented and discussed with respect to the
qualitative stress distributions introduced in the existing theoretical models. Main emphasis of this
paper is set on a discussion of the qualitative stress distribution, which is, to the current state, only
known in theory.
METAKLETT – A Metal Cocklebur
Authors: Hoffmann Hartmut , Hein Christoph , Hong Seok Moo , So Hyun Woo
Published: March 2009

The increasing individualization of products assigns manufacturing companies to new
tasks like manufacturing various products in a more efficient way. This progression in the market
leads on the one hand to a new product design and on the other hand to an improved production
process. Both are necessary to reduce assembly, service and recycling costs. Hence the joining
technology is and will become more and more important. The conventional joining technologies
like welding, bonding, bolting or clamping have their own disadvantages especially in the field of
flexibility. In order to reduce the effort for assembling and disassembling by retaining the
requirements of the connection a new innovative joining technology is needed. In this study a new
joining technology is introduced to become faster and more flexible in assembling and
disassembling. The basic idea of this manufacturing technology comes from a “metal hook and loop
fastener”. A hook and loop fastener consisting of metal has a lot of advantages for the fields of
industrial assembly, service and recycling. Similar to the synthetic hook and loop fastener a metal
one is characterized by easy closing and opening without special tools. And in comparison to the
synthetic hook and loop fastener the transmissible forces are very high. An additional benefit can be
gained for instance in shock absorbing or resistance against chemical and thermal influence. Two
solutions are followed up to invent the “metal hook and loop fastener”. A one-to-one copy of the
conventional hook and loop fastener is constructed in metal and specific solutions for the use of
metal are tested. A conventional finite element program was used in order to optimize the
construction of a metal cocklebur and the results show a good agreement with the experiment.
Microstructural Characterization of Thermo-Mechanical Treated TRIP Steels
Authors: Barcellona A. , Cannizzaro L. , Palmeri D.
Published: March 2009

The increasing demand for the reduction of automobiles CO2 emissions for
environmental preservation leads the automotive industries towards the mechanical components
weight reduction. Sheet steels with multiphase microstructures exhibit favourable combinations of
strength and ductility. The so called TRIP steels have a metastable microstructure that consists of a
continuous ferrite matrix containing a dispersion of hard second phases martensite and bainite.
These steels also contain retained austenite, at room temperature, that represents the source of the
TRansformation Induced Plasticity effect. When the material is subjected to deformation step, the
retained austenite transforms itself into martensite; the produced martensite delays the onset of
necking resulting in a product with high total elongation, excellent formability and high crash
energy absorption. In the present research the steel TRIP 800 zinc coated has been subjected to
different thermo–mechanical treatments in order to evaluate the relation between microstructure of
material and TRIP effects. Whit this aim the microstructural analysis has been performed and the
evaluation of content of different phases has been made by means of the image analysis techniques.
The relation among the strain level, the content of different phases, the thermal treatments and the
work hardening properties of materials have been valued. Furthermore, it has been also highlighted
the dependence of the bake hardening properties of material on the different thermo-mechanical
treatments.
Investigation on the Residual Stress of AISI 4047 Low Alloy Steel Laser Welded
Authors: Casalino Giuseppe , Olabi Abdul Ghani , Cipriani N. , Rotondo A.
Published: March 2009

The residual stress in steel welding can highly influences the performance of the joint
during its working life. Both boundary conditions and metal phase transformations have influence
on the levels of the residual stress in the weld.
In this paper the residual stress for AISI 4047 bead-on-plate samples were measured by strain gage
method after laser welding with different values for the laser speed and power, and focus height.
The laser used for this project was the ROFIN DC 015 Industrial CO2 Slab Laser. This laser,
registered as class 4 laser product in accordance with the European Norm EN 60825 is an high
frequency excited, diffusion cooled C02 gas laser, designed to be used for processing materials in a
industrial environment.
The measurement procedure was performed on all the welded specimens taking notes of 3 strains
(ε1 ε2 ε3) relative to as many gages at different depths, following the American Society for Testing
Materials (ASTM) standard.
Thereafter the residual stresses were calculated by means of a non-linear finite element analysis.
The analysis took in account the thermo-mechanical phenomena with temperature dependent steel
properties. The other considered also the phase transformation and phase-dependent thermal and
mechanical properties.
Experimental Study on Specimen and Grain Size Effects in Uniaxial Tension Test of Aluminum Foil
Authors: Zhou J. , Shan De Bin , Guo Bin , Ma D.L.
Published: March 2009

With the rapidly growing demand for the micro-thin-wall parts, the development of high
accurate forming processes for very thin sheet or foil becomes more and more important. The aim
of this study is to explore the effects of specimen width and grain size on tensile strength of
aluminum alloy 3003 foil in uniaxial tension test. The problem was approached in two ways: firstly,
by reduction of the specimen width, and secondly, by changing the grain size through annealing
crystallization. The uniaxial tension tests were performed on an electronic universal material testing
machine, in which a linear CCD based visual extensometer was used to measure deformation. The
results show that the tensile strength decreases with decreasing specimen width or increasing
surface-to-volume ratio. The tensile strength decreases with decreasing grain size for grain sizes
larger than the specimen thickness.
Prediction on Localized Necking in Sheet Metal Forming: Finite Element Simulation and Plastic Instability in Complex Industrial Strain Paths
Authors: Barata da Rocha Augusto , dos Santos Abel , Teixeira Pedro
Published: March 2009

The use of Finite Element Simulation allows accurate predictions of stress and strain
distributions in complex stamped parts. The onset of necking is strongly dependent on the strain
paths imposed to the parts and therefore the prediction of localized necking can be a difficult task.
Numerical models of plastic instability have been used to predict such behavior and recent and more
accurate constitutive models have been applied in these calculations.
In many manufacturing areas such as automotive, aerospace, building, packaging and electronic
industries, the optimization of sheet metal processes, through the use of numerical simulations, has
become a key factor to a continuously increasing requirement for time and cost efficiency, for
quality improvement and materials saving.
This paper makes an analysis of the evolution of strain gradients in stamped parts. The combination
of Finite Element Analysis with a Plastic Instability Model, developed to predict localized necking
under complex strain paths, shows that it is possible to predict failure with precision. Several
constitutive laws are used and comparisons are made with experiments in stamped benchmark parts.
Considering non linear strain paths, as detected in stamped parts, more accurate failure predictions
are achieved. The work described in this paper shows the need to include a post processor analysis
of failure, capable of predicting the behavior of the material under non linear strain paths. Taking
this phenomenon into account, it is shown that it is possible to increase the accuracy of the onset of
localized necking prediction.
Triangulation Based Digitizing of Tooling and Sheet Metal Part Surfaces - Measuring Technique, Analysis of Deviation to CAD and Remarks on Use of 3D-Coordinate Fields for the Finite Element Analysis
Authors: Hecht J. , Lamprecht K. , Merklein Marion , Galanulis Konstantin , Steinbeck J.
Published: March 2009

The dynamic development of highly accurate optical measuring machines within the last
years pushed the introduction of digitizing techniques to many applications in the fields of quality
control, reverse engineering and rapid prototyping. By projecting fringe patterns onto the object's
surface and recording pictures of the curvature dependant deformation of the pattern, 3D
coordinates for each camera pixel are calculated on the basis of the principle of triangulation. The
generation of a polygon mesh can be used for the analysis of the deviation of a die or a formed part
to the initial CAD data, i.e. by means of full field or section based comparison. This paper presents
the application of the above mentioned techniques on a double sheet hydroforming process. The
gathered 3D data of the clam-shell part as well as of the tooling dies served for the calculation of the
deviation to the respective reference geometry. With respect to the utilization of digitized tooling
data within the finite element analysis, further investigations were performed on the impact of data
reduction strategies. Aiming on the minimization of the necessary number of elements, representing
the tooling surface in a discrete state, and on the request for a sufficient degree of accuracy, these
strategies have to be considered of high priority.
Automatic Process Control in Press Shops
Authors: Hoffmann Hartmut , Zaeh Michael F. , Faass Ingo , Mork Roland , Golle Matthias , Griesbach Bernd , Kerschner Matthias
Published: March 2009

The manufacturing of automotive body components in press lines is a sensitive process.
The quality characteristics of body components vary. These fluctuations are rooted in the fact that
the factors influencing the component quality are varying, e.g., fluctuations of batches regarding
material quality, abrasion or heating of the tool during the production cycle. If a certain quality
characteristic exceeds a predefined range an intervention in the process is necessary. This
intervention is based upon the subjective know-how of the machine operator. Objective information
about the state of the process, like tool temperature or the material quality of the semi-finished
product is not available. Therefore, a lack of knowledge emerges in the interrelations between the
tuning parameters of the system press-tool and the component quality during different stages of the
process (material quality, temperature…).
In this paper a complete concept for an automatic process control in press shops is described. The
concept will be realized in a pilot plant for mass production in the press shop of AUDI AG. The
mechanisms of occurrence of quality defects are shown in the paper, as well as the essential factors
influencing the quality during the mass production of body components in the automotive industry
and their variation. A sensor-system for continuous measurement of influencing variables during
the mass production is presented. The key element of the concept is the non-destructive
identification of material-properties for every single blank. By associating the sensor-data with the
respective quality, a knowledge-based process control can be realized. The purpose is to create a
failure prediction algorithm and make optimal adjustments for each stroke of the moulding press,
respectively. The potential of existing actuators in modern press lines as well as new, tool integrated
proposals for actuators are highlighted.
Experimental Study on Bonding Mechanism between Corroded Bolts and Grout
Authors: Xia Ning , Cao Mao Sen , Ren Qing Wen
Published: March 2009

In this study, an experiment program is presented to study the bonding mechanism
between corroded bolts and grout and in particular the influence on bonding behavior in terms of
different corrosion sections along anchor. With respect to four groups of manufactured bolt
specimens, the noncorroded and the corroded, respectively, on the front, middle and rear section
along anchor, a pullout test is conducted to reveal the relationship between load and loading-end
slip and to investigate the bond-stress distribution characterization along full anchor. Experimental
results show that corrosion product, acting as lubricating effect at the interface between bolts and
grout, can result in the degradation of bonding mechanical behavior. Meanwhile, corrosion on
different sections along anchor has a different effect on the anchorage capacity of bolts. Especially,
corrosion on the front section induces the greatest decrease of anchorage capacity of bolts. Thus, it
is concluded that the front section along anchor is the key region affecting the bonding mechanical
behavior between bolts and grout.
Finite Element Modelling of Small Punch Test on 304H Stainless Steel
Authors: Sunjaya David , Wei Tao , Harrison Robert , Yeung Wing Yiu
Published: March 2009

The small punch test (SPT) is a relatively new mechanical testing technique capable of
utilising small disk-shaped specimens to determine the mechanical behaviour of the test materials.
From the test data, fracture properties in particular the equivalent fracture strain (εqf) can be
determined and the elastic-plastic fracture toughness of a material can be characterised. Finite
element analyses (FEA) of the small punch tests have been performed for the 304H stainless steel in
this study. 304H stainless steel was isothermally aged at 650, 700 and 750oC for durations up to 200
hours. Small punch tests were performed to assess the mechanical properties of the heat treated
materials. Using the input of the true stress-strain curves of material constitutive behaviour, the
theoretical load vs punch displacement curves calculated from the FEA models were found in good
agreement with the experimental results. The fracture thickness of the small punch tested specimens
and the equivalent fracture strain were also be determined for the test materials.
Mechanical Properties of the Intrinsically Conductive Polymer Poly(3,4- Ethylenedioxythiophene) Poly(Styrenesulfonate) (PEDOT/PSS)
Authors: Lang Udo , Dual Jürg
Published: March 2009

In recent years there have been vast efforts to establish organic electronic devices. A key
property of such devices is the possibility to fabricate them on flexible substrates. As the layers are
mechanically stressed during bending, the knowledge of mechanical properties of the materials used
will become very important. In this research the mechanical properties of the intrinsically conductive
and widely used polymer PEDOT/PSS were investigated using a micro tensile test setup. The tensile
tests showed values for Young’s Modulus in the range from 1 GPa to 2.7 GPa, for the tensile strength
in a range from 25 MPa to about 55 MPa and for the total strain at break between 3% and 5%, all of
them depending on relative humidity.
Effect of Microstructure and Sintering Temperature on Fabrication of NITE-SiCf/SiC Composite
Authors: Lee Young Ju , Yoon Han Ki
Published: March 2009

Silicon carbide fiber-reinforced silicon carbide matrix composites (SiCf/SiC composites)
are attractive materials for use in the blankets and divertors of fusion reactors due to their excellent
thermo-mechanical properties and inherently low induced radioactivation. However, the brittle
characteristics of SiC such as low fracture toughness and low strain-to fracture impose a severe
limitation on the practical applications of SiC materials. SiCf/SiC composites can be considered as a
promising candidate in various structural materials, because of their good fracture toughness. In this
composite system, the direction of SiC fiber will give an effect to the mechanical properties such as
fracture toughness and tensile strength. Therefore, it is important to control a proper direction of SiC
fiber for the fabrication of high performance SiCf/SiC composites. .
Prediction of the Scatter of Crack Initiation under High Cycle Fatigue
Authors: Osterstock Stephane , Robertson Christian F. , Sauzay Maxime , Degallaix Suzanne , Aubin Veronique
Published: March 2009

Under fatigue loading, the number of cycles to failure and its associated scatter increase
when the loading level decreases. The High-Cycle Fatigue (HCF) regime is thus characterized by a
large scatter in the number of cycles to failure [1]. Cracks initiation represents an important part of
the lifetime of the structures. A stochastic method is used to study the fatigue crack initiation
prediction in the 316L austenitic stainless steel. The present work proposes to show that this scatter
can be attributed to the random orientation of individual grains, which influences the crack
initiation localization. The stresses in grains are determined by finite element computations (FEM
[2]), using a configuration representative of a polycrystalline aggregate. This approach takes into
account the crystallographic orientations of the grains in the aggregate as well as the deformation
incompatibilities between neighbouring grains due to crystalline anisotropic elasticity and elasticplasticity
[3]. Then, the scatter of the number of cycles to crack initiation is derived from the FEM
stress fields using two fatigue crack initiation criteria: an usual one, Mura’s criterion [4] and a more
recent one [5], based on Discrete Dislocation Dynamics (DDD) simulations and taking into account
plastic slips, cross slip and stress tensor components.
Physical Modelling of Microstructure Development during Technological Processes with Intensive Incremental Deformation
Authors: Mašek Bohuslav , Staňková H. , Malina Jiří , Skálová Ludmila , Meyer Lothar W.
Published: March 2009

Convenient structure adjustment and thereby the achievement of suitable material and
technological properties is one of the very important areas of technological as well as material
research. In general, this issue includes a great number of parameters and variables. To find suitable
technological conditions, it is possible to use various kinds of modeling processes. One of them is
the utilization of thermomechanical simulators, which allow simulating the conditions of the real
processes to be simulated with sufficient accuracy. It is then possible to perform the optimization on
smaller specimens, while monitoring the real conditions with higher accuracy. This method was
used for the optimization of unconventional technological processes for selected alloying strategies
of low-alloyed multiphase steels. These strategies are designed to be applied to technologies, which
combine anisothermal forming and thermomechanical treatment of quasimassive components using
intensive plastic deformation. Incremental deformations allow a high amount of deformation to be
reached. It is also possible to obtain very fine grained structures by a suitable choice of temperature.
By a suitable choice of temperature it is also possible to obtain structures with very fine grain. At
the same time, the morphology of the structure and thus also its final mechanical properties can be
significantly influenced this way.
Damage Detection in an Aluminium Plate with an Active Constrained Layer Damping Treatment
Authors: Chetwynd Daley , Lew T.L. , Worden Keith , Rongong Jem A.
Published: March 2009

This work was conducted as part of the European Union project ARTIMA and it
investigates the potential for a dual use active constrained layer damping treatment for both
vibration control and structural health monitoring. It examines a curved aluminium plate with an
ACLD treatment formed by mounting a large piezoceramic patch with Araldite 2027. The plate was
investigated by ultrasonic Lamb waves generated by the patch, and several smaller piezoceramic
transducers were used as sensors. Damage was simulated by adding incrementally increasing saw
cuts to the plate, and the technique of outlier analysis was used to classify when this damage had
occurred.
Rc Infilled Frame: Shaking Table Tests on a Full Scale Model
Authors: Candigliota Elena , Le Maoult Alain
Published: March 2009

Tests on shaking table have been carried out on a 3D full scale infilled r.c. frame
specimen (55 tons). These tests have been performed by the EMSI Laboratory of C.E.A. Saclay
(France) together with a research team of the Universities of Chieti-Pescara (Italy), Roma Tre (Italy)
and Patras (Greece). These tests are included in Ecoleader European research program.
Many characterization tests of infill components (mortar and bricks) have been performed in the
SCAM Laboratory of the University of Chieti-Pescara while tests on masonry walls were made in
the laboratory of University of Rome 3.
The structure represents the first floor of a two floors frame structure previously tested. The mockup
is a full-scale one storey rc infilled frame with four columns, 3 meters high, with about 4 meters
side square floor and infilled with double bricks wall.
The main aim is to get information about the behavior of real structures. The instrumentation with
about one hundred channels was set up to measure the rc frame response and the different behavior
of the double walls during the tests.
First, monodirectional and bidirectional tests at low seismic intensity (0.10 g and 0.15 g PGA
levels) have been performed on the bare frame in order to characterize its structural characteristics
and to check the design provisions.
Then, the bare frame has been infilled and other tests have carried out at increasing seismic intensity
in order to define its serviceability and ultimate limit states. Monodirectional and bidirectional tests
up to 0.45 g PGA level were carried out. The last sequence included a monodirectional test on the
infilled frame with only two walls. The high seismic input (0.55 g PGA level) was parallel to the
direction of the walls.
In this paper, research program and some main test results are presented.
Comparison of RBF Neural Network and Support Vector Machine on Aero-Engine Vibration Fault Diagnosis
Authors: Xiong Kai , Jiang Dong Xiang , Ding Yong Shan , Li Kai
Published: March 2009

RBF neural network and support vector machine (SVM), two Artificial Intelligent (AI)
methods, have been extensively applied on machinery fault diagnosis. Aero-engine, as one kind of
rotating machine with complex structure and high rotating speed, has complicated vibration faults. As
one kind of AI methods, RBF neural network has the advantages of fast learning, high accuracy and
strong self-adapting ability. Support vector machine, another AI method, only needs a small quantity
of fault data samples to train the classifier and does not need to extract signal features. In this paper,
the applications of two AI methods on aero-engine vibration fault diagnosis are introduced. Firstly,
the principles and algorithm of both two methods are presented. Secondly the fundamentals of
two-shaft aero-engine vibration fault diagnosis are described and gotten the standard fault samples
(training samples) and simulation samples (testing samples). Third, two AI methods are applied to the
vibration fault diagnosis and obtained the diagnostic results. Finally, the advantages and
disadvantages of the two methods are compared such as the computing speed, accuracy of diagnosis
and complexity of algorithm, and given a suggestion of selecting the diagnostic methods.
Assessment of Damage Due to Earthquake-Induced Pounding between the Main Building and the Stairway Tower
Authors: Jankowski Robert
Published: March 2009

The reports after earthquakes indicate that earthquake-induced pounding between
insufficiently separated structures, or their parts, may cause substantial damage or even lead to
structural collapse. One of the most spectacular example of pounding-involved destruction resulted
from interactions between the Olive View Hospital main building and one of its independently
standing stairway towers during the San Fernando earthquake of 1971. The aim of the present paper
is to assess the range and intensity of damage caused by collisions between these reinforced
concrete structures based on the results of a detailed 3D non-linear FEM analysis of poundinginvolved
response. In the study, reinforced concrete has been modelled as layered material with
rebar elements embedded into concrete. The non-linear material behaviour, including stiffness
degradation of concrete due to damage under cyclic loading, has been incorporated in the numerical
model. The results of the study show that pounding may lead to the significant increase of the range
and intensity of damage at the base of the stairway tower, as a lighter structure, as well as may cause
substantial damage at the points of contact. On the other hand, the intensity of damage induced in
the heavier main building has been found to be nearly unaffected by structural interactions.
Minimum Relative Entropy Criterion for Damage Detection and Location
Authors: Kyprianou Andreas , Mares Cristinel , Charalambous Charalambos D. , Mottershead John E.
Published: March 2009

Relative entropy has been employed, as an alternative to other regularization methods, in
solving ill-conditioned linear inverse problems. Damage detection when treated as structural
modification imparted by the damage leads to a linear inverse problem involving frequency response
functions. This problem is amenable to ill-conditioning issues that could arise from the low frequency
response values and noisy experiments. This article formulates and solves using the minimum relative
entropy method the damage detection and localization problem on a simulated cantilever beam.
Automated Operational Modal Analysis as Structural Health Monitoring Tool: Theoretical and Applicative Aspects
Authors: Rainieri Carlo , Fabbrocino Giovanni , Cosenza E.
Published: March 2009

The aim of structural health monitoring for civil structures is not only detection of sudden
or progressive damages but also monitoring their performance under operational conditions or under
some particular environmental issues such as earthquakes. Seismic protection of buildings at risk
can be reached increasing the knowledge of the structural behavior of existing constructions. This
circumstance points out the opportunity of monitoring the performance of civil structures over their
operational lives. The present paper deals with automated Structural Health Monitoring (SHM)
technologies adopted for the School of Engineering Main Building at the University of Naples
“Federico II”. In particular, the attention is focused on the development of an automated procedure
based on the Operational Modal Analysis (OMA) that must ensure the continuous monitoring and
extraction of the modal parameters of the building. Some numerical examples are then discussed in
order to point out effectiveness of the algorithm and relevant issues that need to be improved.
Dynamic Behaviour of Undamaged and Damaged Multilayered Composite Plates
Authors: Gherlone Marco , Di Sciuva Marco
Published: March 2009

The article deals with the application of a higher-order FEM approach to the analysis of
the dynamic behaviour of undamaged and damaged multilayered composite plates. Some numerical
examples show the accuracy of the developed plate mixed finite element, in terms of vibration
frequencies and mode shapes, for different boundary conditions and with different damage
geometries.
On the propagation of Lamb Waves in Viscoelastic Composites for SHM Applications
Authors: Calomfirescu Mircea , Herrmann Axel
Published: March 2009

This paper presents a theoretical model for anisotropic wave attenuation in composites.
The model has been implemented in a software called FIBREWAVE in order to predict dispersion
and attenuation of A0 Lamb wave modes. The required input data are the complex stiffness matrix
coefficients of the unidirectional plies of the composites, which have been measured by an
immersion technique. Good agreement has been observed between predicted and experimental
group velocities and wave attenuations.
An Interval Parameter Perturbation Method for Predicting the Natural Frequency Bounds of Intelligent Truss Structures with Uncertain-But-Bounded Parameters
Authors: Chen Wen Ying , Chu Fu Lei , Yan Shao Ze , Wang Ke Yun
Published: March 2009

The upper and lower bound estimation of natural frequencies for intelligent truss structure
with uncertain-but-bounded parameters is studied in this paper. Firstly, following the finite element
method, the expressions of the interval stiffness and interval mass matrix of piezoelectric intelligent
truss structures are derived directly from the interval parameters. Then, based on the matrix
perturbation and interval extension theory, an interval parameter perturbation method is proposed
for solving the upper and lower bound of natural frequencies. Finally, a 16-bar planar intelligent
truss structure is used as an example to illustrate the applicability and validity of the presented
method, and some useful conclusions are obtained.
Application of the Higher Modes to Crack Identification in a Cantilever Beam
Authors: Liu Yu Xiang , Zhang Wei Wei , Ma Hong Wei
Published: March 2009

Damage detection by the wavelet transform of the fundamental vibration mode receives
much attention recently. However, the higher vibration modes were hardly discussed in past
literatures. As we know they are more sensitive to the crack comparing with the fundamental mode,
which bring abundant damage information. The objective of this study is to show that the first four
modes are available using wavelet transform for crack parameter identification. Specially, using the
higher mode could result in an excellent quality of crack identification when the mode data was
contaminated by noise. But too higher modes have possibly adverse effects on the quality of crack
detection.
Effect of the Strain Rate on the Mechanical Behaviour of Epoxy Adhesives
Authors: Goglio Luca , Peroni Marco , Rossetto Massimo
Published: March 2009

In this paper the dynamic mechanical behaviour of two epoxy adhesives for structural
bonding is investigated. The study has been focused on the influence of the strain rate on the tensile
and compressive strength of specimens made of adhesive. The experimental tests have been
performed with an hydraulic universal testing machine and a tension-compression Hopkinson bar.
The results of the tests show that the σ−ε curve rises significantly increasing the strain rate. The
Cowper-Symonds and Johnson-Cook models of strain rate dependence have been used to fit the
experimental data with unsatisfactory results, thus a poly-linear fit has been adopted.
Lateral Vibration of Footbridges under Crowd-Loading: Continuous Crowd Modeling Approach
Authors: Bodgi Johanna , Erlicher Silvano , Argoul Pierre
Published: March 2009

In this paper, a simple 1D crowd model is proposed, which aim is to properly describe the
crowd-flow phenomena occurring when pedestrians walk on a flexible footbridge. The crowd is
assumed to behave like a continuous compressible fluid and the pedestrian flow is modeled in a 1-D
framework using the (total) mass (of pedestrians) conservation equation. This crowd model is then
coupled with a simple model for the dynamical behavior of the footbridge and an optimized
modeling of synchronization effects is performed. Numerical simulations are presented to show
some preliminary results.
Damage Assessment of Structures - An Air Force Office of Scientific Research Structural Mechanics Perspective
Authors: Giurgiutiu Victor
Published: March 2009

This paper presents the perspective of the Structural Mechanics program of the Air Force
Office of Scientific Research on the damage assessment of structures. It is found that damage
assessment of structures plays a very important role in assuring the safety and operational readiness
of Air Force fleet. The current fleet has many aging aircraft, which poses a considerable challenge
for the operators and maintainers. The nondestructive evaluation technology is rather mature and
able to detect damage with considerable reliability during the periodic maintenance inspections. The
emerging structural health monitoring methodology has great potential, because it will use on-board
damage detection sensors and systems, will be able to offer on-demand structural health bulletins.
Considerable fundamental and applied research is still needed to enable the development,
implementation, and dissemination of structural health monitoring technology.
Reconstruction Problem of Reinforced Concrete Beams under Harmonic Excitations
Authors: Kokot Seweryn , Zembaty Zbigniew
Published: March 2009

A damage detection method based on harmonic structural vibrations has been applied to
reconstruct realistic damage patterns of reinforced concrete beams. It was shown that the application
of a hybrid method (genetic algorithm and Levenberg-Marquardt minimization technique) makes it
possible to effectively reconstruct the flexural stiffness drops as small as 10-20% with the maximum
error of 4%. The error increases to about 7 to 9% with the presence of 1% measurement noise.
Multiscale Modelling of Softening Materials
Authors: Gitman I.M. , Askes H. , Sluys L.J.
Published: March 2009

A hierarchical multiscale procedure for softening materials is proposed in this paper. A standard multiscale model has been analysed with respect to macro-level mesh dependence and meso-level cell size dependence. In order to eliminate spurious macro-level mesh dependence and meso-level cell size dependence a coupled-volume approach has been proposed. A discussion on the various interacting length scales in the model is included.
Cohesive Zone Modeling of Mode I Fracture in Adhesive Bonded Joints
Authors: Alfano Marco , Furgiuele Franco , Leonardi A. , Maletta Carmine , Paulino Glaucio H.
Published: March 2009

This paper deals with the application of Cohesive Zone Model (CZM) concepts to study mode I
fracture in adhesive bonded joints. In particular, an intrinsic piece-wise linear cohesive surface
relation is used in order to model fracture in a pre-cracked bonded Double Cantilever Beam (DCB)
specimen. Finite element implementation of the CZM is accomplished by means of the user element
(UEL) feature available in the FE commercial code ABAQUS. The sensitivity of the cohesive zone
parameters (i.e. fracture strength and critical energy release rate) in predicting the overall
mechanical response is first examined; subsequently, cohesive parameters are tuned comparing
numerical simulations of the load-displacement curve with experimental results retrieved from
literature.
Interfacial Fracture Toughness of APS Thermal Barrier Coating under High Temperature
Authors: Qi Hong Yu , Yang Xiao Guang , Li Rui
Published: March 2009

Thermal barrier coating (TBC) is an essential requirement of a modern gas turbine engine.
The TBC failure is the delamination and spallation. The oxidation damage under high temperature
results in the reduction of interfacial adhesion. The interfacial fracture toughness is an important
property to analyze the TBC failure. The interfacial fracture toughness of ceramic coating - bond
coating has been researched in the past. However, the facture toughness of the bond coating -
substrate due to the Al depletion was very few studied. In this study, a NiCrAlY bond coating by air
plasma spray (APS) was deposited. The substrate was directionally solidified superalloy (DZ40M).
Isothermal oxidation was performed at 10500 for 100h. Using the HXZ-1000 micro-hardness
equipment, the five different times was chosen to test the hardness and the crack length, and then the
fracture toughness was obtained. While the oxidation exposure time increased at 10500, the hardness
of the substrate close to the bond coating decreased with the increase of the bond coating’ hardness.
Meanwhile, the interfacial fracture toughness of the bond coating - substrate decreased because of the
Al depletion.
Boundary-Singular Integral Equation Method to Calculate the Bending Center and Stress Intensity Factors of Cracked Cylinder under Saint-Venant Bending
Authors: Tang Xin Yan
Published: March 2009

Using single crack solution and regular plane harmonic function, the Saint-Venant
bending problem of a cracked cylinder with general cross section is formulated in terms of two sets
of boundary-singular integral equations, which can be solved by using the methods for combination
of boundary element and singular integral equation methods. The concept of bending center used
in strength of materials is extended to this bending problem. Theoretical formulae to calculate the
bending center and stress intensity factors in cracked cylinder are derived and expressed by the
solutions of the integral equations. Based on these results, some numerical examples are given for
different configurations of the cylinder cross section as well as the crack parameters.
Mesoscopic Numerical Simulation Method for Fracture of Concrete
Authors: Ying Zong Quan , Du Cheng Bin , Sun Li Guo
Published: March 2009

A numerical method from the mesoscopic point of view is proposed to describe the
fracture process of concrete. At mesoscopic level, concrete is considered as a three-phase composite
consisting of mortar matrix, coarse aggregate and interfacial transition zone (ITZ) between them.
According to the grading of coarse aggregate obtained from sieve analysis, the random aggregate
models with polygonal aggregates were generated by Monte Carlo random sampling principle. In
this work, the tensile cracking is assumed to the only failure criterion at the mesoscopic scale; and
the stress-separation law based on the fictitious crack model is adopted to allay the sensitivity on
mesh size in the softening regime. The nonlinear finite element method is used in the simulation of
concrete under bend loading. The influence of the shape of aggregate on the macroscopic response
of concrete is also investigated. Numerical results show that the strength of the specimen with
circular aggregate is higher than the specimen with arbitrary polygonal aggregate. The predicted
bending strength agrees well with experimental data.
Microstructure and Strengthening Mechanism of TiCp/ZA-12 Composites
Authors: Xiang Wang , Ying Guo Bing
Published: March 2009

TiCp/ZA-12 composites have been fabricated by XDTM method and stirring-casting
techniques. Microstructure of the composites has been studied by means of scanning electron
microscopy (SEM) and transmission electron microscopy (TEM). The results show that TiC particles
distribute uniformly in ZA-12 matrix alloy. The interface between reinforcements and matrix alloy is
very clean, and there is not interface reaction between TiC particles and ZA-12 matrix alloy. The tests
for mechanical properties reveal that the tensile strength, yield strength, elastic modulus and hardness
of the composites are improved obviously due to the incorporation of TiC particles. The
strengthening mechanisms are attributed to the following factors: dispersion strengthening of TiC
particles, grain refinement of ZA-12 matrix alloy and high-density dislocations existing in ZA-12
alloy.
Investigation of the Ballistic Performance of Two Different Polymer Matrix Composites
Authors: Colakoglu Mehmet
Published: March 2009

Light armors are used to protect people against light weapons for military and nonmilitary
purposes such as protecting police and civilians against criminals or protecting people even
in hunting. Today, they are usually manufactured from polymer matrix composites due to their high
stiffness/weight ratio. The good ballistic property means the measure of absorbability of the kinetic
energy of a bullet or projectile without any major injury on the person. Designing the armor for only
penetration is not enough for protection. The backside deformation of the armor must be also
investigated because the projectile can produce not only bruises and lacerations of the surface of the
skin, but can also damage internal organs. In this study, the backside deformation is determined
experimentally and analytically for Kevlar 29/Polivnyl Butyral and Polyethylene fiber composites.
Fatigue Behavior of Corroded Structural Steel Members in Boundary with Concrete
Authors: Kainuma Shigenobu , Hosomi Naofumi , Kim In Tae
Published: March 2009

In this research, fatigue tests were carried out to investigate the fatigue behavior of
corroded structural members in boundary with concrete. Specimens were corroded by accelerated
exposure tests and then used in the fatigue tests. FEM analyses were also performed on the models of
the corroded surfaces of the specimens and the simulated corrosion surfaces to investigate the stress
concentration at the corrosion pit in the boundary. The experimental and analytical results clarified
the fatigue behaviors of corroded steel plates in boundary with concrete. The method for evaluating
and predicting the fatigue life of corroded steel members were also proposed.
Microstructure and Mechanical Properties and Corrosion Behavior of Ti-Mo-Sn Alloys
Authors: Zheng Yu Feng , Wang Yan Bo
Published: March 2009

The phase constitution, mechanical properties, and corrosion behavior of TiMoSn alloys
were investigated by means of XRD, tensile test, electrochemical measurement and XPS techniques.
The XRD analysis results showed that at room temperature TiMoSn alloys are mainly composed of β
phase, with minor content of α" phase, in as-cast and solid solution treated conditions. The tensile test
results indicate that the elastic moduli of the Ti-Mo-Sn alloys are in the range of 52~74GPa. The
electrochemical measurement results indicate that TiMoSn alloys have excellent corrosion resistance
in simulated body fluid. The XPS analysis results reveal that the passive films of TiMoSn alloys after
polarization consist of TiO2, SnO2 and Mo2O5.