bluuebunny/crossref_metadata_2025 huggingface dataset:
Computational Toolset for X-Ray Spectral Analysis
Authors: Shon Cheol Soon , Kim Ho Kyung , Cho Min Kook , Cheong Min Ho , Lim Chang Hwy , Kim Jung Min
Published: March 2009

We have designed a computational tool for generating X-ray photon spectra for a range of
applications both in diagnostic radiology and mammography. As a library, we have adapted the
spectral data based on the interpolating polynomials methods by Boone et al [5,6] as well as the
computer data files given by Cranley et al [8]. The attenuated spectra for element or compound
materials can be calculated based on the mass-attenuation coefficients from NIST (National Institute
of Science and Technology), which were also incorporated as a database. Furthermore, a function that
a user can generate any filter material by editing the NIST data has been implemented. Parameters
related to the beam quality, such as mean photon energy, fluence, exposure, half-value layer (HVL),
etc., are considered as important outputs. All of functions and database are integrated in a form of
graphical user interface (GUI) by using Microsoft Visual C++TM. This self-developed
spectrum-generating code can be usefully served to design X-ray sensors. In this study, we have
applied the code to estimate quantum efficiency and charge collection efficiency in various detector
materials.
Application of the X-Ray CT Technique for NDE of Wood in Field
Authors: Lee Sang Joon , Kim Kwang Mo , Lee Jun Jae
Published: March 2009

NDE (Nondestructive Evaluation) of wood was performed using X-ray CT technique in
order to determine the applicability of this technology to ancient wooden buildings in the field. Two
main objectives were studied to consider applicability as well as accuracy. First, the most suitable
number of radiographs for reconstructing proper X-ray CT images was determined. Secondly, X-ray
CT images using SIRT were reconstructed using various numbers of radiographs in order to consider
the possible effects of absent projection data in field applications. As a result of this study, 9
radiographs were determined to be the most suitable number for this application. Brown-rotted part in
wood was also detected by X-ray CT images using 9 radiographs. It was concluded that even there
exists some absent projection data, CT images can be reconstructed with high accuracy.
Design of Adaptive Filter for Health Monitoring on a Gearbox
Authors: Lee Sang Kwon , Lee Jung Soo
Published: March 2009

Impulsive vibration signals in gearbox are often associated with faults, which lead to due
to irregular impacting. Thus these impulsive vibration signals can be used as indicators of machinery
faults. However it is often difficult to make objective measurement of impulsive signals because of
background noise signals. In order to ease the measurement of impulsive signal embedded in
background noise, we enhance the impulsive signals using adaptive signal processing and then
analyze them in time and frequency domain by using time-frequency representation. This technique is
applied to the diagnosis of faults within laboratory gearbox.
The Nondestructive Evaluation Method for the Optical Glass Lens by Resonant Ultrasound Spectroscopy
Authors: Lee Kil Sung , Kim Seung Hoon , Min Han Ki , Kim Young Nam , Cha Cheon Seok , Kim Ji Hoon , Jeong Sang Hwa , Yang In Young
Published: March 2009

In this research, we proposed nondestructive evaluation method of a flaw in an optical glass
lens by resonant ultrasound spectroscopy (RUS). An optical glass lens is used for improving signal
coupling between fibers, emitters and detectors. The shape of optical glass lens is an aspherical lens
with 3mm in length and 6.35 mm in diameter. For nondestructive evaluation of an aspherical lens, we
made of the measuring system by RUS. For flaw evaluation by the RUS to verify the data obtained
from the experiment, we carried out simulation by explicit finite elements method, and compared the
experimental results with simulation results. Also, we compared the resonant frequencies of
specimens with some defect with those of acceptable specimens. The histogram drawn from these
data and the available resonance mode surveyed were used to classify the acceptable specimens in the
plant.
Characteristics of Fiber Bragg Grating Sensors with Various Grating Lengths Embedded in Composite Materials
Authors: Kang Dong Hoon , Hong Chang Sun , Kim Chun Gon
Published: March 2009

Because of their good multiplexing capabilities, fiber Bragg grating (FBG) sensors are being studied more actively than any of other fiber optic sensors. The application fields of FBG sensors have been mainly focused on composite materials through embedding rather than through surface attachments. However, there are many limitations on the embedding of FBG sensors into composite materials because of the birefringence that is induced when FBG sensors are not embedded parallel to the reinforcing fibers. This study investigates the fabrication of FBG sensors that have various grating lengths, good multiplexing capabilities, better stability from birefringence, and ease in production. The signal characteristics of FBG sensors are also verified through the cure monitoring of two composite laminates.
A Study on the Method of Vibration Analysis for Korean High Speed Train by the On-Line Test
Authors: Park Chan Kyoung , Kim Ki Whan , Mok Jin Yong , Kim Young Guk , Kim Seog Won
Published: March 2009

The Korean High Speed Train (KHST) has been tested on the Kyongbu high speed line and
the Honam conventional line since 2002. A data acquisition system was developed to test and prove
the dynamic performance of the KHST, and the system has been found to be very efficient in
acquiring multi-channel data from accelerometers located all over the train. Also presented in this
paper is an analysis procedure which is simple and efficient in analyzing the acceleration data
acquired during the on-line test of the KHST. The understanding of system vibration mode for a
railway vehicle is essential to evaluate the characteristics of a dynamic system and to diagnose the
dynamic problems of the vehicle system during tests and operations. Methods based on homogeneous
linear systems are not realistic because real systems have nonlinear characteristics and are strongly
dependent on environmental conditions. In this paper an efficient method of vibration analysis has
been proposed and applied for the KHST to evaluate its vibration mode characteristics. The results
show that this method is suitable to estimate the system vibration modes of the KHST.
Image Reconstruction of Blockage in the Continuous and Stepped Pipelines by Noninvasive Acoustic Method
Authors: Jung Sung Soo , Cho S.I. , Kim Young Tae , Cheong C.U. , Kim Ho Chul
Published: March 2009

The image of a semi-circular blockage and location in the uniform and stepped pipe was
reconstructed by measuring the eigen-frequency shift of the resonance and anti-resonance
frequencies of multi-sine acoustic waves. In this study we have used different boundary conditions
from previous works of Wu and Fricke [1] and De Salis and Oldham [2] to determine the blockage
cross-sectional area and position. The results agreed with real fractional cross sectional area and
position in the both continuous and stepped pipes. New approach showed a better quality of
reconstructed image with small ripple number and the false dummy blockage signal was also
reduced. The present method of blockage image reconstruction is a noninvasive nondestructive and
can meet the integrity evaluation implementation for all types of transmission pipeline
Dynamic Impact Analysis of a Rotating Beam Having a Tip Mass
Authors: Lim Hong Seok , Yoo Hong Hee
Published: March 2009

Flexible structures undertaking impact while undergoing overall motion can be found in
several industrial products these days. Transient motion and stress induced by impact should be
considered elaborately to extend the life of the products. In the present study, a modeling method for a
flexible beam with a tip mass that undertakes impact while undergoes large overall motion is
presented. The tip mass takes the impact force and the transient responses of the beam are calculated
by employing the assumed mode method. The stiffness variation caused by the large overall motion is
considered in this modeling. The effects of the tip mass and the angular speed of the beam on the
transient responses are investigated.
Portable Neutron Source Using by Spherically Convergent Beam Fusion Device for Nondestructive Testing
Authors: Park Jeong Ho , Ju Heung Jin , Ko Kwang Cheol
Published: March 2009

This paper presents experimental and simulation results of discharge in spherically convergent beam fusion device. The deuterium-deuterium (D-D) fusion reaction in that device will generate neutron. The experimental device is consists of a vacuum chamber made of stainless steel, spherical mesh type anode and concentric grid cathode of 5cm diameter. The pressure of chamber maintained constant by injecting gas and pulsed voltage applied to grid cathode. A star mode discharge which has possibility of neutron generation was observed.
Development of In-Situ SUB-100nm Particle Detection in Vacuum System
Authors: Ahn Kang Ho , Kim Yong Min
Published: March 2009

A feasibility test for real-time fine particle measurements in vacuum semiconductor
processing equipment has been conducted. The approach in monitoring particles in process
equipment is an installation of a sensor at a critical location inside the process equipment (hence the
term ‘in-situ’) to track free particle levels in real-time. Common method for particle detection in a
process chamber today is a use of test wafer with a laser wafer scanner. However, this method does
not give a real time information of the particle status in the process chamber. In this paper, a new
method has been developed to detect particles in real time in vacuum system for particles smaller than
an optical method can detect. The system consists of a particle charging region and a particle detection
region in a vacuum system. Particles with 50nm are successfully detected at about 10 torr region.
Analysis of Residual Stress Components Developed in Cold Drawing by Finite Element Method
Authors: Baek Tae Hyun
Published: March 2009

Predicting the behavior of steel during deformation process under service conditions is one
of the main challenges in cold drawing. In this paper, finite element method was used to analyze the
distribution of residual stress components in a rod with respect to different area reductions in cold
drawing process. Cold drawing brought sunken-in deformation at the bottom land of the rod that was
in accord with the result obtained from the analysis using ABAQUS. The results obtained from finite
element analysis were in close agreement with the determined high-accuracy measurements.
Assessment of Fire-Induced Damage on Concrete Segment of Shield TBM Tunnel
Authors: Chang Soo Ho , Choi Soon Wook , Bae Gyu Jin
Published: March 2009

To protect underground structures and passengers from fire, it is essential to characterize
fire-induced damage on the construction materials for underground structures. However, it is almost
impossible and uneconomical to carry out full-scale fire tests in tunnels that are under public usage. In
this study, a high temperature furnace capable of simulating RABT (Richtlinien für die Ausstattung
und den Betrieb von Straßentunneln) fire curve was newly designed and manufactured. In the fire
tests, furnace temperature is set to reach 1,200 within five minutes after ignition. The temperature
of 1,200 was maintained for one hour, and the fire was extinguished after two hours had elapsed.
From the temperature measurement by thermocouples embedded in test specimens, the depth of lost
concrete was estimated to reach approximately 20 cm from the surface that was exposed to fire. In
addition, the alteration of physico-mechanical properties and microstructures of concrete segments
after fire tests were investigated from core specimens. The results show that the deterioration of
material properties was up to 10 cm from the surface of the remaining concrete block
Assessment of the Integrity of Piles by Impedance Log Technique
Authors: Lai Jiunn Ren , Yu Chih Peng , Liao Shu Tao
Published: March 2009

The objective of this paper is to investigate the capabilities of the Impedance Log method in
profiling the geometry of a pile along its length. The main idea of this method is to introduce a
transient stress wave into the pile and then utilize the reflected signals to obtain the impedance profile
of the pile. Any anomaly, which results in changes in impedance, would be detected by this method.
In this study, four model piles with plan defects of weak zone or neck were constructed and tested
using Seismic Echo, Impulse Response, and Impedance Log pile integrity nondestructive testing
methods. Results of these tests show that interpretation of signals using the Impedance Log method is
more straightforward than the other two methods. It is concluded that the Impedance Log technique is
a tool with high potential for evaluating the integrity of piles.
Detection of Debonding in Concrete Members Retrofitted with FRP Using Electromagnetic and Ultrasonic Methods
Authors: Rhim Hong C. , Woo Sang Kyun , Song Young Chul
Published: March 2009

Microwave and ultrasonic methods have been used for the detection of debonding
between concrete and fiber-reinforced plastic (FRP). To determine the capability of the microwave
method in detecting thin delamination between two materials of concrete and FRP, concrete
specimens are made with the dimensions of 600 mm (length) x 600 mm (width) x 50 mm (depth).
Specimens have artificial delamination of 5 and 10 mm thick Styrofoam, which represent
debonding in structures. Then, the specimens are partially covered with 1.5 mm thick FRP on the
top of 3 mm thick epoxy. A horn antenna with a center frequency of 15 GHz and a frequency
bandwidth of 10 GHz is used for the measurements. By transmitting and receiving microwave
signals from the horn antenna, differences have been detected for the different types of the targets.
Also, measurements using ultrasonic method at 5 kHz have been made on the same series of
specimens. This work is directed toward a development of an effective and practical microwave
based non-destructive evaluation methodology for the detection and quantification of damages in
FRP-covered reinforced concrete members in bridges and buildings.
Evaluation of Motorized Rotating Pancake Coil Probe Signals Simulated by Numerical Analysis in Steam Generator Tubes
Authors: Yoo Joo Young , Song Sung Jin , Kim Chang Hwan , Jung Hee Jun , Choi Young Hwan , Kang Suk Chull , Jung Hyun Kyu
Published: March 2009

In the present study, the synthetic signals from the combo tube are simulated by using
commercial electromagnetic numerical analysis software which has been developed based on a
volume integral method. A comparison of the simulated signals to the experiments is made for the
verification of accuracy, and then evaluation of five deliberated single circumferential indication
signals is performed to explore a possibility of using a numerical simulation as a practical calibration
tool. The good agreement between the evaluation results for two cases (calibration done by
experiments and calibration made by simulation) demonstrates such a high possibility.
Multi-Coil Eddy Current Probe for the Detection of Circumferential Cracks in Tubing
Authors: Kim Young Joo , Ahn Bong Young , Kim Ki Bok , Kim Young Gil
Published: March 2009

Conventional eddy current bobbin probes, multi-pancake and/or rotating pancake probes,
and transmit-receive eddy current probes are currently utilized in testing metal tubing. Each method
has respective strengths and weaknesses. This paper proposes another eddy current probe with new
features. The structure is designed to be sensitive to circumferential cracks, which are not easily
detected with ordinary bobbin coil probes. The directions of the magnetic field and the eddy current
around the coil were considered in design of the probe structure. Signals of these probes from the
artificial defects were acquired and analyzed. Experimental results show that the developed probes
are more sensitive to circumferential defects than comparable ordinary bobbin probes. In addition, the
new probes are insensitive to axial defects. By employing both the new probes and ordinary bobbin
probes, more reliable ECT can be performed.
A Study on Estimation of the Pipe Fracture Characteristics
Authors: Park Jae Sil , Seok Chang Sung
Published: March 2009

In order to analyze the elastic-plastic fracture behavior of a structure, the fracture resistance
curve of the material should be known. However, it is difficult to evaluate the fracture characteristics
with an experiment on the piping system. Instead, the fracture toughness obtained from standard
specimen tests is used to analyze the structure and assess the fracture characteristics of the total
structure. It is known that toughness data from the standard specimen test are conservative to predict
fracture behavior of the real piping. Thus the fracture resistance curve by the fracture test of the real
scaled pipe specimen would be applied to the integrity evaluation for the piping system. However, it is
not only difficult to perform but also very expensive to perform full-scale pipe tests. The objective of
this thesis is to propose a method to estimate the fracture resistance curve of a pipe from the result of
standard specimen fracture test. To estimate the fracture resistance curve for a pipe specimen, load –
load-line displacement records of a standard specimen were transformed to those of the pipe
specimen. The load ratio method was proposed in order to calculate the crack length from load –
crack mouth opening displacement records for the pipe specimen. To prove the validity of this
estimation results, fracture tests for pipe specimens were performed. Consequently the applicability of
the proposed method was investigated by comparing estimated results with tested results.
Sensitive Ultrasonic NDE of Tightly Closed Small Cracks in Carbon Steel Structures
Authors: Ahmed S. Reaz , Saka Masumi
Published: March 2009

Nondestructive evaluation of tightly closed small cracks in carbon steel has been investigated under no load conditions. The investigation has been carried out by using a new ultrasonic method of testing, which has the capability of dealing with smaller tight cracks sensitively. Tight closure of small fatigue cracks in carbon steel plates is realized when the measured responses are compared with the calculated responses of the identical open cracks. Highly sensitive characteristic of the present method is verified through the comparison of the results with those obtained by the standard ultrasonic method of testing.
Failure Analysis of Reinforced Concrete Bridge Column Using Cohesive and Adhesive Interfaces
Authors: Rhee In Kyu , Lee Hee Up , Lee Jun S. , Kim Woo
Published: March 2009

This study examines the performance of adhesive and cohesive interfacial crack model in
assessing the brittle shear behavior of reinforced concrete bridge columns. The quarter-scale
reinforced concrete columns tested at the University of California at San Diego by Xiao et al. (1993)
to explore the ductility of reinforced concrete columns under cyclic loading. The three columns R-1,
R-3 and R-5 with different transverse reinforcement are considered for finite element failure analysis.
A Study on Ultrasonic Testing for Nondestructive Evaluation of Thermal Fatigue Crack in Pipelines
Authors: Yi Won Geun , Lee Min Rae , Lee Joon Hyun , Choi Sang Woo , Lee Bo Young
Published: March 2009

Pipelines of nuclear power plants undergo high pressure and temperature. Thermal
stratification typically occurs in the surge line and the main feed water lines by flow and this
stratification will initiate and propagate thermal fatigue cracks. This may cause rupture and leakage
and it is a serious problem to nuclear power plants operation. Therefore it is very important to detect
and measure thermal fatigue cracks. In this study, thermal fatigue cracks were generated in
austenitic stainless steel specimens by a thermal cycle in notched pipes and weld jointed pipes.
Ultrasonic techniques were used to evaluate the thermal fatigue crack depth. When ultrasonic waves
propagate from an angle beam probe to thermal fatigue cracks, waves are reflected and diffracted.
Crack depth was evaluated by the reflected signals from back wall and diffracted signals from the
crack tip, but diffracted signals were too weak to detect so the reflected signals were more useful.
The TOFD and dB drop methods were used in this study. The TOFD method is uses a time delay of
diffracted signal from the crack tip. The dB drop method is an application of an amplitude
decreasing rate by a probe moving distance.
Uniform Model and Fracture Criteria of Annularly Breached Bars under Bending
Authors: Li You Tang , Rui Zhi Yuan , Yan Chang Feng
Published: March 2009

A uniform model, in which the crack, V-notch, U-notch and arc are described as breach uniformly, is put forward in this paper. The tip radius, depth and field angle of breach are regarded as the parameter of annularly breached bar. The stress field and displacement field near the tip of the annularly breached bar under bending, in which takes fα(a/b) as its descriptive parameter, was given. All forms of breaches according to the change of tip radius, depth and field angle were discussed. The effects of parameters on fα(a/b) in bending were analyzed. The criteria for the safety design and fracture design both of which on fα(a/b) were obtained. The results not only can be applied widely to anti-fracture design but also be used for reference in anti-fatigued design in product lifecycle management.
Thermographic Diagnosis of Whiplash Injury with/without Radiculopathy
Authors: Zhang Ho Yeol , Cho Bo Young , Kim Han Sung , Cho Yong Eun
Published: March 2009

Whiplash injury is produced by the hyperextension of the neck followed by flexion.
These patients have no abnormality in radiologic evaluation.
We collected 39 patients and divided into two groups; Group 1 (neck pain without radiculopathy)
and Group 2 (neck pain with radiculopathy). Thermal differences at neck and arm were checked
with IR thermography. 1 patient was taken the IR thermography periodically until recovery from his
symptom.
Group 1 showed that subjective painful area on the neck was changed to hyperthermic, but the
arm temperature was normal. Group 2 showed that subjective painful area on the neck was changed
to hyperthermic, and painful arm was changed hyperthermic, which can be differentiated from
hypothermic change in cervical disc herniation patients. Thermal differences were gradually
reduced with the same consequence of the patient’s symptom recovery.
IR thermography can be used to diagnose the whiplash injury and also to determine a symptom
recovery. It is possible to differentiate the whiplash injury with radiculopathy and pre-existing
cervical disc disease.
Medical Thermography Evaluation of Anti-Fatigue Mat to Prevent Muscular Skeletal Disorder
Authors: Park Se Jin , Lee Hyuna Ja
Published: March 2009

Therefore the objective of this study was to examine the differences of calf temperature by
infrared thermal imager between on anti-fatigue matt and on the floor without mat. The subjects were
instructed to wear short pants. It was measured with bare feet because influence of shoes and socks
was to except. Subjects worked during 1 hour on the mat or without mat and next day without mat or
on the mat. The order and load of work kept regularly. In this study, there was also a significant
difference (p < 0.001) in the calf skin temperature between conditions, and calf temperature was
higher when the subjects were standing on the mat than when they were standing on the floor without
mat. By providing an elastic surface to stand on, a matt simulates muscle activity in feet and legs
promote blood circulation. As a cross-modality evaluation, electromyogram was measured. There
was the significant difference in Median Frequency (p < 0.001) and Median Power Frequency (p <
0.05) of EMG between two conditions. Median Frequency and Median Power Frequency showed a
tendency to more decrease on the floor.
Optical Inspection of Interfacial Thermal Strains in IC Composite Microstructures
Authors: Morita Yasuyuki , Arakawa Kazuo , Todo Mitsugu
Published: March 2009

Thermal deformation behaviors of electronic packages, stacked-MCP (multi chip package) and SOJ (small outline J-leaded package) were measured by phase-shifting moiré interferometry. This method was developed using a wedged glass plate as a phase shifter to obtain displacement fields with a sensitivity of nanometer scale. Digital image processing was also introduced to determine the strain distributions quantitatively. In stacked-MCP, thermal loading was applied from room temperature 25°C to two elevated temperatures (75 and 100°C), and thermal strains were then examined at these two elevated temperatures. The results showed that the normal strain εxx concentrated at the ends of two silicon chips, and the transverse strain εyy increased between the two silicon chips. The shear strain γxy increased at the end of the lower silicon chip to 0.30% from 0.17% when the temperature increased by 25°C. In SOJ, the thermal strains were investigated with the two packages before and after mounted on PWB (printed wiring board). The results showed that the strains increased by about 50% when the SOJ was mounted on the PWB.
Fiber Orientation State Depending on the Injection Mold Gate Variations during FRP Injection Molding
Authors: Kim Jin Woo , Lee Dong Gi
Published: March 2009

Because of orientation and separation, injection molded products are heterogeneous and anisotropic. These heterogeneousness and anisotropy have a vast influence on mechanical properties of molding material and product characteristics. It is well known that fiber orientation state in fiber-reinforced polymeric composite has a profound effect on dynamic qualities like intensity, rigidity, and etc. To measure the fiber orientation of injection molded product's weld part, we first X-rayed moldings and recognized this photo by using an image scanner. Then, image processing method, which uses intensity difference in measuring fiber orientation state, is applied. Through these procedures, we can analyze the influence of molding's fiber orientation state according to mold gate changes. Fiber orientation is related mainly with the mold gate positions than with fiber content or mold temperature. When the distance from the gate increases, by matrix and reinforcement's flow speed differences, fiber orientation occurred. As diversion flow occurred at the end of fluid flow, fiber oriented at a right angle to the flow, and this is the same effect of weld line formation.
NDE Characterization and Mechanical Behavior in Ceramic Matrix Composites
Authors: Kim Jeong Guk , Kwon Sung Tae , Kim Won Kyung
Published: March 2009

Several nondestructive evaluation (NDE) techniques, including ultrasonic C-scan, X-ray computed tomography (CT), and infrared (IR) thermography, were employed on ceramic matrix composites (CMCs) to illustrate defect information that might effect mechanical behavior and to analyze structural performance of CMCs. Prior to tensile testing, through C-scan and CT analyses results, the qualitative relationship between the relative ultrasonic transmitted amplitude and porosity based on CT was exhibited. An IR camera was used for in-situ monitoring of progressive damages and to determine temperature changes during tensile testing. Moreover, scanning-electron microscopy characterization was used to perform microstructural failure analyses. This paper describes the use of nondestructive evaluation (NDE) techniques to facilitate the understanding of tension behavior of CMCs.
Creep Crack Interaction of High Temperature Structure with Multiple Cracks
Authors: Si Jun , Xuan Fu Zhen , Tu Shan Tung
Published: March 2009

The interaction behavior of two non-aligned through-wall cracks in flat plates is
investigated by the finite element method (FEM) under extensive creep condition. The
time-dependent fracture parameter C*-integral along the crack tips are calculated and compared to
the results of a single crack of the same size. For comparison purpose, the interaction of stress
intensity factors (SIFs) is also examined in the study. The results indicated that interaction of
multiple cracks is different between the time- dependent fracture characterized by C*-integral and
linear elastic fracture noted by SIF. The magnifying factors of time-dependent fracture are obviously
larger than that of the linear elastic fracture cases. Therefore, the current re-characterization rule for
multiple cracks developed from linear elastic fracture analysis may lead to a non-conservative result
and should be modified when it is used in the assessment of time dependent failure.
Experimental Study of Steel Fibre Bridging Action on Crack Propagation in Fibre Reinforced Concrete
Authors: Xu Zhi Hong , Liang Wen Yin , Liang Yu Jing
Published: March 2009

In this paper the bridging action of steel fibres on the model I crack propagation has been studied experimentally for steel fibre reinforced concrete (FRC). From the experimental results three main conclusions are obtained. First, the bridging action increases with the number of the steel fibres across the crack surface and the stress intensity factor near the crack tip decreases thereby. Second, bridging action increases with the strength of the matrix because the matrix with higher strength can provide stronger interfacial bond with steel fibres. Third, the interfacial bonding gets damaged when the steel fibres under cyclic loads and the bridging action degrades with the cycle number.
Thermal Ageing Effects on the Residual Fatigue Strength of AA2618-T6511 Aluminium Alloy
Authors: Molari Pier Gabriele , Morelli Piero , Maldotti Sergio , Poli Tito
Published: March 2009

This work presents the results of an experimental investigation on the effects of thermal
ageing over the residual fatigue strength of AA2618-T6511 aluminium alloy.
Among others, this kind of light alloy finds practical applications in highly stressed engine
components, such as pistons, that are typically subjected to both thermal and fatigue loads. Thermal
cycles are responsible for ageing phenomena, that involve the precipitation of silicates, with a
corresponding progressive damage of the microstructure and weakening of the mechanical
characteristics of the material.
Artificial ageing has been reproduced in laboratory by means of thermal cycles controlled in time
and temperature. These variables have been correlated to the hardness values measured on the
surface of specimens. Bending fatigue tests have been performed on a rotating machine in a
temperature controlled environment. The experimental S-N diagram is finally presented, as a
function of the tested temperature, in order to provide a design tool for the fatigue life estimation of
AA2618 components.
DBEM Crack Growth Simulation and Experimental Results for a Multi-Layer and Multi-Material Aeronautic Panel
Authors: Citarella Roberto G. , Silvestri M. , Apicella A.
Published: March 2009

A special specimen was created cutting a rectangular notched area from the surrounding
of the upper left corner of a wide body aircraft door. This part of the aircraft skin is made of
different layers with variable thickness and material (titanium or aluminum). Then a fatigue traction
load was applied and some notches were cut in the different layers in order to speed up the crack
initiation and reproduce a realistic crack scenario. Such through cracks were monitored during their
propagation along the specimen width, in order to have available for the simulation a realistic initial
scenario and experimental propagation data useful for the correlation with the simulated crack path
and growth rates. In particular an innovative DBEM modelling approach was devised, using a
commercial code (BEASY), capable of explicitly modelling the different test article layers with
their rivet connections even in a two-dimensional approach. The results of the simulation show a
satisfactory correlation with the experimental crack path and growth rates even for such a complex
problem: three different panels (one skin with two doublers), made of different materials, each one
with a variable thickness and connected through numerous rivets (whose shear stiffness is taken into
account for the simulation).
The Effect of the Property of Non-Linear Viscosity on the Interfacial Debonding of Particulate-Reinforced Polymers
Authors: Chen Jian Kang , Chang Liu Hong
Published: March 2009

The debonding of a rigid particle embedded in an infinite non-linear viscoelastic material is
investigated in this paper. Under sphere-symmetric deformation, a non-linear equilibrium equation
expressed by velocity of a particle in the viscoelastic matrix material is derived. The strain rate is
obtained by solving non-linear equation in terms of iterative method. According to the energy
criterion, the critical instant of the interfacial debongding is calculated. Numerical results show that
the influence of non-linear viscosity on the interfacial debonding is significant.
Fracture Mechanics Analysis of 2-D FGMs by a Meshless BEM
Authors: Zhang Chuan Zeng , Gao Xiao Wei , Sladek Jan , Sladek Vladimir
Published: March 2009

This paper presents a fracture mechanics analysis in continuously non-homogeneous, isotropic, linear elastic and functionally graded materials (FGMs). A meshless boundary element method (BEM) is developed for this purpose. Young’s modulus of the FGMs is assumed to have an exponential variation, while Poisson’s ratio is taken as constant. Since no simple fundamental solutions are available for general FGMs, fundamental solutions for homogeneous, isotropic and linear elastic solids are used in the present BEM, which contains a domain-integral due to the material non-homogeneity. Normalized displacements are introduced to avoid displacement gradients in the domain-integral. The domain-integral is transformed into a boundary integral along the global boundary by using the radial integration method (RIM). To approximate the normalized displacements arising in the domain-integral, basis functions consisting of radial basis functions and polynomials in terms of global coordinates are applied. Numerical results are presented and discussed to show the accuracy and the efficiency of the present meshless BEM.
Fracture Mechanics and Fatigue Cracks Reduction of Polymeric Asphalt Pavements
Authors: Haghi Akbar K. , Arabani Mahyar , Shakeri Morteza
Published: March 2009

The objective of this research was to advance understanding of the cracking process via
laboratory and computational studies and to convey the obtained results in a form that can be
utilized for the prediction of cracking in flexible pavements. The primary purpose of this project
reported herein was to evaluate the effects of tire cords on the fatigue response of asphalt mix and to
develop recommendations for improving the fatigue performance of asphalt pavements. Based on
the results presented in this paper, the indirect tensile strength tests can propose as a simple
performance test for fatigue cracking of asphalt mixture. The results clearly demonstrate a great
potential procedure for the fatigue cracking evaluation of asphalt mixture.
Punching Shear Strength Considering Cumulative Damage for FRP Strengthened Bridge Decks under Fatigue Loading
Authors: Park Cheol Woo , Sim Jong Sung , Lee Tai Sik
Published: March 2009

This study investigates the punching shear strength of concrete bridge decks strengthened
with various fiber reinforced polymer (FRP) materials, carbon fiber sheet (CFS), glass fiber sheet
(GFS) and carbon fiber grid (CFG). This study performed fatigue loading tests on the strengthened
bridge decks with different fatigue loading levels. Based on the experimental results, a damage
index was determined considering the damage mechanics and was applied to the plastic punching
shear strength model for the evaluation of the punching shear strength with respect to the number of
fatigue loading cycles. The developed model seems to successfully estimate the punching shear
strength of damaged bridge decks with sufficient reliability. It is anticipated, therefore, that the
developed model may help improving the design of strengthening of damaged bridge deck panels.
Fracture Analysis of Side-Gusset Plate of Combined-Roller Based on Finite Element Method
Authors: Qu Li Gang , Gao Hang
Published: March 2009

The side-gusset plate is connector of the combined-roller, which is the key component of
the High-pressure Grinding Roller equipment that is applied in crushing raw iron ore, Fracture
occurred at the bottom of the side-gusset plate while the roller’s operation. For exploring the reason
of fracture, the stress distribution and corresponding critical location of the side-gusset plate were
computed and analyzed according to two working situations based on finite element method. The
analysis result illustrates that it is the failure of infant mortality because of overloading, not belongs
to fatigue behavior, with the presence of the component operating time and the fracture
cross-section’s granular feature as well. This result is a reliable foundation for succeeding redesign
and manufacturing of side-gusset plate and other component, the feasible plan was brought forward
to improve the component operation’s stability.
Simulation Study on Impact Damage of Aircraft Panel Structure under Stress
Authors: Hou Man Yi , Li Shu Lin , Jiang Yang Yi , Li Shou An
Published: March 2009

Based on ANSYS/LS-DYNA code, the finite-element models were created to simulate the
response of the aircraft panel structure impacted by high velocity projectile. The models proved to be
effective through the comparison between the results of simulation and relative experiments. Then the
impact process was simulated respectively considering the states of various types of stress in the
panel. Through analyzing the simulation results, the influence of various stress states in the panel on
impact response and damage mechanism was summed up. The conclusions indicated that the stress
and particularly compression stress in aircraft panel structure can facilitate much more deformation
and damage when the panel suffers high velocity impact.
Failure Behavior of Pressurized Spherical Tanks Depending on Manufacturing Method
Authors: Lee Ho Sung , Yoon Jong Hoon , Yi Yeong Moo
Published: March 2009

There are numerous applications of pressure vessels in aerospace field for storing liquid or
gaseous media. Generally the metallic vessels have been manufactured by welding two hemispheres,
which are machined or spin-formed. In this study, the solid state bonding method was utilized with
blow forming to manufacture aerospace titanium tanks. This solid state joining technology replaced
the welding process and without any secondary material or liquid phases in bonding process,
homogeneous microstructure was obtained at bonding interface. Using this method, a titanium tank of
a space vehicle was manufactured and during a hydraulic pressurizing test, the strain and acoustic
emission signals are observed to investigate the effect of solid state bonding method on the failure
mode and performance of the tank.. This result was compared with the one made by conventional
method of spin forming and welding. The result shows that the pressurization rate and the acoustic
emission signal increasing rate provide a similar tendency for a vessel of integrity, while the signal
increasing rate is much higher than the pressurization rate for a vessel with welding defects. It is clear
that the failure mode of the solid state bonded tank is different from the welded tank due to the
completely united interface by diffusion process.
Phase Constitution, Mechanical Property and Corrosion Resistance of the Ti-Nb Alloys
Authors: Wang Bao Lai , Wang Yan Bo , Zheng Yu Feng
Published: March 2009

Recently, people devote to the development of Ni-free shape memory alloys in order to
avoid the Ni-hypersensitivity and toxicity and pursue absolute safety. The shape memory effect and
superelasticity have been reported in the biomedical Ti-Nb based alloys. The purpose of this paper
is to report the phase constitution, tensile property, shape memory effect and corrosion resistance of
the Ti-Nb alloys. The phase constitutions of the Ti-Nb alloys are investigated by means of X-ray
diffraction (XRD). The results reveal that β+α′′ phases are presented in the Ti-35Nb alloy and only
β phase in the Ti-52Nb alloy at room temperature. The tensile test and bending tests indicate that
the Ti-35Nb alloy exhibits shape memory effect. The shape recovery ratio is near to 80% when the
bending strain is 4.4% and decreases with the increase of the total bending strain. The corrosion
resistance of the Ti-Nb alloys in the Hank's solution and artificial saliva (pH=7.4) at 37 are
investigated by OCP, Tafel and anodic polarization methods. The results indicate that the Ti-35Nb
alloy has a better corrosion resistance in the artificial saliva and can replace the Ti-Ni alloy in the
dental application. In the non-oral condition, the Ti-52Nb alloy may be preferable.
Numerical Simulation on 3-D Crack Coalescence in Rock-Like Materials Containing Pre-Existing Surface Closed Flaws
Authors: Zuo Yu Jun , Tang Chun An , Liang Zheng Zhao , Zhang Yong Bin
Published: March 2009

Using newly developed 3 dimensional Rock Failure Process Analysis code RFPA3D,
numerical simulations on samples of rock-like material containing pre-existing surface closed flaws
under uniaxial compressive loading are conducted to investigate the failure mechanism and crack
coalescence modes. Friction in closed flaws is modeled by inserting ideal elasto-plastic materials into
the flaws. The simulations replicate most of the phenomena observed in actual experiments, such as
initiation and growth of wing and secondary cracks, crack coalescence, and the macro-failure of the
sample. For the samples containing three pre-existing surface closed flaws, four different patterns of
crack coalescence are obtained in our simulations. The four different patterns of coalescence are the
combination of T mode, S mode, TS mode and C mode, i.e. type (C+S mode), (T+S mode), (S
mode) and (C+S mode). A total of four types of samples containing three surface parallel inclined
frictional flaws are numerically simulated.
Vibration Analyses of Cylindrical Hybrid Panel with Viscoelastic Layer Based on Layerwise Finite Elements
Authors: Oh Il Kwon , Cheng Tai Hong
Published: March 2009

Based on full layerwise displacement shell theory, the vibration and damping
characteristics of cylindrical sandwiched panels with viscoelastic layers are investigated. The
transverse shear deformation and the normal strain of the cylindrical hybrid panels are fully taken into
account for the structural damping modeling. The layerwise finite element model is formulated by
using Hamilton’s virtual work principle and the cylindrical curvature of hybrid panels is exactly
modeled. Modal loss factor and frequency response functions are analyzed for various structural
parameters of cylindrical sandwich panels. Present results show that the full layerwise finite element
method can accurately predict the vibration and damping characteristics of the cylindrical hybrid
panels with surface damping treatments and constrained layer damping.
Fatigue Assessment of High Loaded Bolted Bar Connection Using Strain-Life Approach
Authors: Glodež Srečko , Knez Marko , Kramberger Janez , Aberšek Boris
Published: March 2009

The paper deals with the problem of service life evaluation of counterweight bar bolted
connection by means of computational analysis and experimental testing. Computational analysis
has been performed using the local strain-life approach (ε-N), where appropriate material properties
for treated high strength steel S1100Q has been determined previously. Experimental fatigue tests
of bars were carried out in a specially constructed hydraulic pulsation machine. Comparison of
computational and experimental results shows a reasonable agreement.
Fuzzy-Random FOSM and its Application in Low Cycle Fatigue Life Reliability Analysis of an Aeronautical Engine Turbine Disk
Authors: Xu You Liang , Liu Cheng Li , Lu Zhen Zhou
Published: March 2009

An approximate analytical method is presented to analyze reliability for the structure
with fuzzy-random uncertainty in basic variables. On the basis of equivalent transformation from
fuzzy possibility distribution (FPD) to random probability distribution (RPD), this contribution
expands first order and second moment method (FOSM) for random reliability to that for
fuzzy-random reliability. The expanded FOSM is illustrated by the way of the fuzzy-random low
fatigue life reliability analysis about an aeronautical engine disk affected by fuzzy-random
uncertainty. Comparison between the FOSM and the numerical simulation for the fuzzy-random
reliability demonstrates the precision of the presented computational model.
Initiation and Crack Propagation in Complex Structures Considering Total Value of Loading
Authors: Aberšek Boris , Flašker Jože , Glodež Srečko
Published: March 2009

For accurate determination of the service life we must take into account the loading, which
are in most cases random loading of variable amplitude, the geometry and material properties of
construction elements which are known not to be constants. The more precise these input parameters
are modeled; the more precise and reliable are the results.
In our paper we will deal in detail with the model of crack initiation and propagation in the
complex structures as a basis of the algorithm for calculating the service life. For determination of
the service life for the area of short cracks we used Bilby, Cottrell and Swinden model which is
based on the theory of continuously distributed dislocations and we complemented it with random
generation of structure of material before cracks. For the long crack we have developed a stochastic
model for determination of service life.
Evaluation of Fatigue Life of Automotive Bevel Gear
Authors: Kim Jae Hoon , Kim Duck Hoi , Lee Young Shin , Kim Gi Gwang
Published: March 2009

This paper presented the results for experimental investigations and numerical analysis
performed with the aim of studying on fatigue life of hobbed and cold forged bevel gears used in
automobiles. To evaluate the bending fatigue strength improvement by cold forging process, fatigue
test and analysis were performed. For the monotonic fatigue loading, bending fatigue test and
analysis were carried out. To simulate the real driving condition, random fatigue loading was
defined here, and the random fatigue analysis was also performed. It was concluded that fatigue life
and crack initiation sites of automotive bevel gear were well agreed with the test results. Fatigue
lives for hobbed and cold forged bevel gear from experimental and analytical investigation were
also presented and compared.
Effects of the Length of Carbon Nanotube (CNT) in CNT Reinforced Composites
Authors: Wang Q. , Sun X. F. , Ozaki Kimihiro
Published: March 2009

In this paper, the strength of the singular stress field near the ends of the CNTs in
composites was analyzed to clarify the effects of the CNT length on stress filed in the CNT reinforced
composites when studying the fracture toughness. The singular stress field was separated into two
types of singularities, symmetric and skew-symmetric, near the ends of CNTs according to the
deformation and loading types. The stress intensity factors of the singular stress field were calculated
for these two types of singularities. The effects of the CNT length in CNT reinforced composites on
these stress intensity factors were investigated.