bluuebunny/crossref_metadata_2025 huggingface dataset:
Ultrasonic Estimation of Clamping Force in High-Tension Bolts
Authors: Jhang Kyung Young , Quan Hai Hua , Ha Job , Kim Noh Yu
Published: March 2009

High-tension bolts have been used widely for the clamping of many kinds of large
structures. In these bolts, the estimation of clamping force has been regarded as the main issue in the
evaluation of clamping condition. This paper proposes a method using ultrasonic wave, which is
based on the dependency of sound speed on the stress. In order to verify the usefulness of the proposed
method, two kinds of experiments are carried out. The first one involves the measurement of sound
speed when the bolt is stressed by the tension tester, and here, the relationship between the exact axial
force and sound speed is calibrated. The result shows good agreement with the expected linear
relationship between sound speed and axial stress. The second experiment involves the measurement
of axial stress by the proposed method when the bolt is stressed by the torque wrench. The results are
coincident to the strain gage measurement. From these results, we can conclude that the proposed
method is indeed useful in evaluating clamping force in high-tension bolts.
Optimal Accelerometer Locations for Structural Health Monitoring Using Time-Domain System Identification
Authors: Kwon Soon Jung , Lee Hae Sung , Shin Soo Bong
Published: March 2009

The paper presents two algorithms for determining optimal accelerometer locations for
structural health monitoring when structural condition is assessed by a system identification scheme
in time-domain. The accelerometer locations are determined by ranking the components of an
effective independent distribution vector computed from a Fisher information matrix. One of the
proposed algorithms formulates a Fisher information matrix by multiplying acceleration matrix with
its transpose and the other as a Gauss-Newton Hessian matrix composed of acceleration sensitivities
with respect to structural parameters. Since the structural parameters cannot be known exactly in an
actual application, a statistical approach is proposed by setting an error bound between the actual and
the baseline values. To examine the algorithm, simulation studies have been carried out on a two-span
planar truss. The results using locations selected by the two algorithms were compared.
Structural Health Monitoring for Carbon Fiber/Carbon Nanotube (CNT)/Epoxy Composite Sensor
Authors: Lee Sang Il , Yoon Dong Jin
Published: March 2009

Structural health monitoring for carbon nanotube (CNT)/carbon fiber/epoxy composite
was verified by the measurement of electrical resistivity. This study has focused on the preparation of
carbon nanotube composite sensors and their application for structural health monitoring. The change
of the electrical resistance was measured by a digital multimeter under tensile loads. Although a
carbon fiber was broken, the electrical connection was still kept by distributed CNT particles in the
model composites. As the number of carbon fiber breakages increased, electrical resistivity was
stepwise increased. The CNT composites were well responded with fiber damages during the
electro-micromechnical test. Carbon nanotube composites can be useful sensors for structural health
monitoring to diagnose a structural safety and to prevent a collapse.
A Study on the Elastic Wave Propagation in the Telecommunication Pole Having Different Subsurface End Condition
Authors: Kim H.W. , Kim Dong Soo , Kang W.K.
Published: March 2009

Alternative construction methods and a simple method for identifying pole’s subsurface
end condition using elastic wave propagation test were proposed. After twelve prototypes of poles
having different subsurface end conditions were constructed, horizontal loading tests and elastic wave
propagation tests were performed. It was found that there was a close correlation between the 1st
resonant frequency and maximum pulling force. The results of this study will provide a key to identify
the telecommunication pole’s foundation.
Modified Surface Wave Velocity Measurement Technique in Concrete
Authors: Shin Sung Woo , Yun Chung Bang , Song Won Joon , Lee Joon Hyun
Published: March 2009

A modified one-sided measurement technique is proposed for Rayleigh wave (R-wave)
velocity measurement in concrete. In this study, the maximum energy arrival concept is adopted to
determine the wave velocity by employing its continuous wavelet transform. Experimental study was
performed to show the effectiveness of the proposed method. Results reveal that the proposed method
can be effectively used to measure the R-wave velocity in concrete structures.
Remote Sensing of Bridge Displacement Using Digital Image Processing Techniques
Authors: Lee Jong Jae , Shinozuka Masanobu , Cho Soo Jin
Published: March 2009

In this study, an optical method of real-time displacement measurement of such bridges
was carried out by means of digital image processing techniques. A commercially available digital
video camera combined with a telescopic device takes a motion picture of the target panel with known
geometry, which is installed on the measurement location of a bridge. The displacement of the target
is calculated based on the captured images in real-time manner using image processing techniques,
which require a texture recognition algorithm, projection of the captured image, and calculation of the
actual displacement using target geometry and number of pixels moved. For the purpose of
verification of the presented method, a laboratory test was made using shaking table test and the
measured displacement by image processing techniques was compared with the data from a
contact-type sensor, a linear variable differential transformer (LVDT). The proposed method gave
close results to a conventional sensor. Field tests were carried out on a bridge with steel plate girders
and a bridge with steel box girders. The test results gave sufficient dynamic resolution in frequency as
well as the amplitude.
Evaluation of Hidden Corrosion in a Thin Plate Using a Non-Contact Guided Wave Technique
Authors: Park Ik Keun , Kim Tae Hyung , Kim Hyun Mook , Kim Yong Kwon , Cho Yong Sang , Song Won Joon
Published: March 2009

In this paper, study on evaluation of thickness reduction in a thin plate with guided waves is presented. Ultrasonic guided wave techniques have been widely studied and successfully applied to various non-destructive tests with the advantage of long range inspection. In addition to application of guided waves to NDT, non-contact methods for ultrasonic wave generation and detection have become very useful and well combined with guided wave techniques due to their capability of ultrasonic wave generation and reception in surface of high temperature or on rough surface. An advanced non-contact technique for detection of thickness reduction simulating hidden corrosion in thin plates using guided waves is proposed. The proposed approach uses EMAT(Electro-Magnetic Acoustic Transducer) for the non-contact generation and detection of guided waves in aluminum plates. Interesting features of the dispersive behavior in selected wave modes are used to detect plate thinning. The experimental results show that the mode cutoff measurements provide a qualitative measurement of thinning detects and change in the mode group velocity can be used as quantitative parameter of thinning depth measurement.
Non-Contact Ultrasonic Inspection Technology of Fillet Weldments Monitoring
Authors: Park Ik Keun , Kim Hyun Mook , Park Tae Sung , Kim Yong Kwon , Cho Yong Sang , Song Won Joon
Published: March 2009

It's not easy to detect the defects in fillet weldment which is widely used in various building structures and power plants just with nondestructive inspection due to its complex geometrical shape and difficult access. But it's easy to detect the cracks on the surface or just below the surface of fillet weldment heel part if surface SH-wave, among ultrasonic wave modes, is applied. The traditional ultrasound inspection using surface SH-wave is usually a contact method using piezoelectric transducer, so it's not suitable for a field application because the reliability of inspection varies depending on field environments such as couplant, contact pressure and pre-process, etc. Therefore, the necessity for non-contact ultrasound inspection is increasing. This study proposes non-contact ultrasound inspection method using EMAT (electro-magnetic acoustic transducer), and presented non-contact ultrasound inspection method for fillet weldment through experimental verification.
Identification of AE Source in Corrosion Process
Authors: Prateepasen Asa , Jirarungsatean Chalermkiat , Tuengsook Pongsak
Published: March 2009

In this paper acoustic emission (AE) was implemented to detect and study the corrosion
on austenitic stainless steel grade AISI 304. Two tests were conducted at room temperature using an
acidic 30% Chloride solution in passive tests procedure and 3% NaCl solution in electrochemical
process. From the experimental works, it appeared that AE signals could be detected during
corrosion. Data were studied in time and frequency domain to characterize and to find out the
relation between AE parameter and corrosion. In addition the source of generated acoustic signals
and corrosive mechanism in the different corrosive environment condition were discussed.
Assessment of Mechanical Degradation in Pressure Vessel Steel by Morphological Analysis of Carbides
Authors: Byeon Jai Won , Kwun S.I. , Kang Kae Myung
Published: March 2009

In this study, mechanical degradations in 2.25Cr-1Mo steel were evaluated by quantitative morphological analysis of carbides. Based on the morphology, carbides were classified as globular, fine acicular, rod, and grain boundary one. Mean size of carbides were determined as a function of morphology and thermal degradation time at 630°C. Area fraction of grain boundary carbides and fraction of grain boundary M6C carbides were observed to increase rapidly in the initial stage of degradation and then gradually afterwards. Both mean size of globular carbide and fraction of grain boundary M6C carbides were linearly correlated with strength. Potentials of carbide morphology analysis as a health monitoring technique were discussed, in term of correlation coefficient with strength.
Creep Rupture Studies of Zirlo Tubing Using Ring Tensile Specimen
Authors: Bae Bong Kook , Seok Chang Sung , Koo Jae Mean , Kim Hyung Ick , Murty K.Linga
Published: March 2009

A burst rupture test has been mainly used for evaluating the burst properties of internal
pressurized tubes. Although the burst creep test provides accurate results, its complicated and
material-wasting process makes it difficult to perform this test. In the burst test, it is known that the
hoop stress is a main reason of burst, so it can be expected that the burst rupture properties are
strongly related with the hoop creep rupture properties. A ring test is occasionally used for obtaining
the hoop directional properties of tube-shaped structures. In this study, the creep rupture properties of
Zirlo tubing are investigated at temperature ranging from 365 to 570 using the ring specimens. An
analysis of the fractography was performed and the estimation of service life with Larson-Miller
parameter was conducted. Finally, In view of the Dorn equation of power-law, the creep mechanism
was determined and discussed.
Fluid Structure Interaction Analysis on Wall Thinned Pipes
Authors: Chang Yoon Suk , Song Ki Hun , Lee Sang Min , Choi Jae Boong , Kim Young Jin
Published: March 2009

The wall thinning due to erosion, corrosion and flow accelerated corrosion is one of critical
issues in nuclear industry. To secure against loss of integrity of pipes with a flaw, ASME Code
Section III and Code Case N-597 etc have been used in design and operating stages, respectively.
However, despite of their inherent conservatisms, it may reach unanticipated accidents due to
degradation at local region. In this paper, a new evaluation scheme is suggested to estimate
load-carrying capacities of wall thinned pipes. At first, computational fluid dynamics analyses
employing steady-state and incompressible flow are carried out to determine pressure distributions in
accordance with conveying fluid. Then, the discriminate pressures are applied as input condition of
structural finite element analyses to calculate local stresses at the deepest point. A series of combined
analyses were performed for different fluid flow velocities as well as d/t, Rm/t and l/t ratios. The
efficiency of proposed scheme was proven from comparison with conventional analyses results and it
is recommended to consider the fluid structure interaction effect for exact integrity evaluation.
Role of Intraoperative Infrared Thermography for Prediction of Successful Percutaneous Radiofrequency Sympathectomy for Palmar Hyperhidrosis
Authors: Park Jung Yul , Park Juno , Kim Sang Dae , Kim Se Hoon , Lim Dong Jun
Published: March 2009

Tests for successful surgical results for refractory palmar hyperhidrosis in the past usually
involve starch test, plethysmograpy, and direct measurement of skin temperature. However, these
tests are either inconvenient, inadequate or unable to be used during operation. Authors have used IR
thermography during percutaneous radiofrequency sympathectomy to verify its usefulness as guide
for evaluating the successful results. A total of 14 patients with persistent palmar hyperhidrosis were
included. Average age was 28.2 years (range 21-36 years). Average duration of symptom was 24
months. All procedures were percutaneously performed under local anesthetics. Procedures include
position the patient in prone position and introduction of three 21-guage RF TIC needles with 10 mm
bared tip electrode to T2 and T3 ganglion in each side under C-arm guidance. After obtaining correct
placement of electrode, a series of three lesions at each level with 90 °C for 120s were done.
Successful lesioning was confirmed by from marked widening of pulse amplitude with an increase in
hand skin temperature (>2 °C) by thermographic examination during operation. Average follow up
period was 14.4 months. All patients tolerated the procedure and responded immediately to have
dryness sensation of hands, most of which remained for rest of follow up period. Twelve patients
(85.7%) reported as having about 80% of initial responses and one patient about 60% at 12 months
postoperatively. Another patient who lost about 30-40% of initial response had undergone second
procedure 3 months later with similar success. There were no complications related to the procedures
and there were no rebound phenomenon. With regards to the role of intraoperative thermography in
determining the successful results, it seems to provide clear-cut information whether these patients
received proper treatments for future successful outcome. Thus, authors believe IR thermogrpahic
examination is simple, feasible way of demonstration of completeness of sympathectomy in object
way during surgical procedure that can be used as a guide for successful outcome.
Nondestructive Determination of Ply-Layup Error in Cured/Uncured CF/Epoxy Composites
Authors: Kweon Young Sub , Im Kwang Hee , Hsu David K. , Fei Dong , Ra Seung Woo , Lee Kil Sung , Park Je Woong , Sim Jae Ki , Yang In Young
Published: March 2009

A nondestructive technique would be very beneficial, which could be used to test the part
before (uncured) and after curing CF/Epoxy. A new method for nondestructively determining the
ply layup in a composite laminate is presented. The method employs a normal-incidence
longitudinal ultrasound to perform C-scan of ply interfaces of the laminate, and extracts fiber
orientation information from the ultrasonic reflection in the laminate. Using two-dimensional
spatial Fourier transform, interface C-scan images were transformed into quantitatively angular
distribution plots to show the fiber orientation information therein and to determine the orientation
of the ply. In order to develop these methods into practical inspection tools, an automated system
using a motor has been developed for different measurement modalities for acquiring ultrasonic
effects of ply-layup error. Therefore, it is found that the efficiency of developed system shows
between the practical testing and model in characterizing cured/uncured ply-layup error of the
laminates. A C-scan image of a ply interface seem to have the ply-layup error information of the
two neighboring plies of CF/Epoxy composite laminates.
Quantitative Vibration Amplitude Measurement Using Stroboscopic Phase Shifting ESPI
Authors: Jung Hyun Chul , Kim Koung Suk
Published: March 2009

The stroboscopic phase shifting ESPI (SPS-ESPI), one of the optical vibration amplitude
measurement techniques, is presented. Although the general PS-ESPI can be used for quantitative
deformation measurement of the object, this technique cannot measure the vibration amplitude with
itself only. The phase change due to the vibration of the object cannot be calculated with general
PS-ESPI correctly. Therefore, in order to solve this problem, the stroboscopic illumination must be
introduced to the general PS-ESPI. This can be done by using a device called as AOM (Acousto-Optic
Modulator). In this paper, SPS-ESPI is applied to measure the vibration amplitude of the square plate
whose all edges were fixed. The natural frequencies and mode shapes are analyzed by using ANSYS.
And the results obtained by using SPS-ESPI technique are compared with that of the ANSYS
analysis. The vibration amplitude is measured by using SPS-ESPI quantitatively.
Laser-Generated Ultrasonic Technique for Inspecting Delamination in CFRP
Authors: Park Won Su , Choi Sang Woo , Lee Joon Hyun , Seo Kyeong Cheol , Byun Joon Hyung
Published: March 2009

For improving quality of a carbon fiber reinforced composite material (CFRP) by
preventing defects such as delamination and void, it should be inspected in fabrication process. Novel
non-contacting evaluation technique is required because the transducer should be contacted on the
CFRP in conventional ultrasonic technique during the non-destructive evaluation and these
conventional contact techniques can not be applied in a novel fiber placement system. For the
non-destructive evaluation of delamination in CFRP, various methods for the generation and
reception of laser-generated ultrasound are applied using piezoelectric transducer, air-coupled
transducer, wavelet transform technique etc. The high frequency component of laser-generated
guided wave received with piezoelectric sensor disappeared after propagating through delamination
region. Air-coupled transducer was tried to be adopted in reception of laser-generated guided wave
generated by using linear slit array in order to generate high frequency guided wave with a frequency
of 1.1 MHz. Nevertheless, it was failed to receive high frequency guided wave in using air-coupled
transducer and linear slit array. Transmitted laser-generated ultrasonic wave was received on
back-wall and its frequency was analyzed to establish inspecting technique to detect delamination by
non-contact ultrasonic method. In a frequency spectrum analysis, intensity ratio of low frequency and
center frequency was approvable parameter to detect delamination.
Finite Element Analysis Model for Estimating the Dynamic Crush Strength of the Spacer Grid Assembly for PWRs
Authors: Song Kee Nam , Yoon Kyung Ho , Lee Jae Jun , Park Kyung Jin
Published: March 2009

The spacer grid assembly, which is an interconnected array of slotted grid straps and welded at the intersections to form an egg crate structure, is one of the main structural components of the nuclear fuel assemblies of a Pressurized light Water Reactor (PWR). The spacer grid assembly is structurally required to have enough crush strength under lateral loads due to lateral seismic accelerations, lateral Loss Of Coolant Accident (LOCA) blowdown forces, and shipping and handling loads so that the fuel rods are maintained within a coolable geometry, and that the control rods are able to be inserted. The ability of the spacer grid assembly to resist the lateral loads is usually characterized in terms of its dynamic and static crush strengths, which are acquired from the relevant tests. In this study, dynamic buckling tests and finite element analyses on spacer grid assembly specimens are carried out. As a result of the comparisons, the analysis results are in good agreement with the test results to within an 8 % difference range. Therefore, we could predict the crush strength of a spacer grid assembly in advance before performing the dynamic buckling test.
Analysis of Interlaminar Stresses and Failure around Hole Edge for Composite Laminates under In-Plane Loading
Authors: Li Lei , Yue Zhu Feng
Published: March 2009

The stress characterization around the hole in a composite plate under tensile stress has
been studied by the analytical method in this paper. The distribution of the stress components has
been presented. With the Hashin Failure Criterion, the failure characterization and different failure
modes by the analytical method and finite element method are then studied. The possibility of the
failure in different modes is compared. It is found that the fiber breakage, matrix failure and
delamination are dominant. The place of the failure is between 70 degree and 90 degree to the
loading direction in this paper. The results from analytical method and finite element method can
agree with each other. And they are all confirmed by the experiment results.
Crystal Plasticity Analysis of Thermal Deformation and Dislocation Accumulation in ULSI Cells
Authors: Sato Michihiro , Ohashi Tetsuya , Maruizumi Takuya , Kitagawa Isao
Published: March 2009

Thermal stress, plastic slip deformation and accumulation of dislocations in shallow trench isolation (STI) type ULSI devices when the temperature drops from 1000 し to room temperature are analyzed by a crystal plasticity analysis cord. The results show that dislocation accumulation takes place at the temperature range over 800 し, and the difference of 6 MPa in the lattice friction stress at 1000 し!causes increase of dislocation density more than 1.6 times. Dislocations generate and accumulate at the shoulder part of the device area and bottom corners of the trench. Dislocations are categorized into two groups. In one group, dislocation lines are mostly straight and parallel to the trench direction, and in the other group, dislocations make half loop type structure. Possibilities for the suppression of dislocation accumulation through control of lattice friction stress at high temperature region are discussed.
Reconstruction of the Material Probabilistic S-N Relations under Fatigue Life Following Lognormal Distribution I-without Given Confidence
Authors: Zhao Yong Xiang , Yang Bing , Zhang Wei Hua
Published: March 2009

Fatigue reliability theory has recently verified that the sampling size related effect should
be taken into account by confidence (C). However, most of the historic probabilistic S-N curves are
given to only consider the scattered regularity effect by survival probability (P). Therefore, a
reconstruction method of the historic curves is investigated to consider the sampling size effect. An
effort is made on addressing the true production that the sampling size is less than 20 for material
specimens and 10 for structural component specimens. A Monte Carlo simulation approach is first
established to reconstruct the test S-N data. And then, the P-C-S-N curves are reconstructed with a
general maximum likelihood principle. The practice for 40Cr steel has clearly indicated that, beyond
all doubt, the reconstructed curves has overcome the shortages of the historic data.
Evaluation of Stress Intensity Factors in Biaxial Tensile Stress using Thermalelasticity and Photoelasticity
Authors: Shimamoto Akira , Ohkawara Hiroshi , Zhao Hong Yang
Published: March 2009

Stress intensity factor K is analyzed by measuring distribution of sum of the principal
stresses around slit tip by an infrared stress measuring device. Under the biaxial tensile stress, both
K-values of the isotropic materials with slit angle 0° and 45° show there is no influence of the slit
angle at Mode I. The tolerance of the measured K-values of the test specimens which are compared
with measured K-values by photoelastic method are around 10-20and these increase as applied
cyclic load increases. These tolerance can be reduced up to about 8% by modifying measurements.
The effectiveness of the thermoelastic stress measurement method to KI value analyzing under
biaxial tensile stress was confirmed.
Sliding Wear Characteristics of Plasma Sprayed 8%Y2O3-Zr Coating for Post-Spray Heat Treatment
Authors: Chae Young Hun , Suh Min Soo , Kim Seock Sam
Published: March 2009

The purpose of this study is to investigate the wear characteristics of yttria-stabilized zirconia coating as a function of effect on post-spray heat treatment. We concerned that the residual stress is due to during cooling from a high deposition temperature. We will focus on the tribological wear performance as a magnitude of residual stress. The effect of residual stress as post-spay heat treatment temperature will be discussed. The plasma-sprayed 8%Y2O3-Zirconia coating is studied to know the relationship between phase transformations and wear properties after post-spray heat treatment. Wear tests is carried out with ball on disk type on 50 N, 70 N, 90 N under room temperature. The transformation of phase and magnitude of residual stress are measured by x-ray diffraction method (XRD). Tribological characteristics and wear mechanism for post-spray heat treatment is observed by SEM.
Analysis of Edge Bridged Crack in Bimaterial Anisotropic Half-Space
Authors: Profant Tomáš , Kotoul Michal , Ševeček Oldřich
Published: March 2009

The problem of an edge-bridged crack terminating perpendicular to a bimaterial interface in a half- space is analyzed for a general case of elastic anisotropy bimaterials and specialized for the case of orthotropic bimaterials. The edge crack lies in the surface layer of thickness h bonded to semi-infinite substrate. It is assumed that long fibres bridge the crack. Bridging model follows from the assumption of “large” slip lengths adjacent to the crack faces and neglect of initial stresses. The crack is modelled by means of continuous distribution of dislocations, which is assumed to be singular at the crack tip. With respect to the bridged crack problems in finite dissimilar bodies, the reciprocal theorem (ψ - integral) is discussed as to compute, in the present context, the generalized stress intensity factor through the remote stress and displacement field for a particular specimen geometry and boundary conditions using FEM.
Tribological Characteristics Manufactures SiC by Liquid Phase Sintered Method
Authors: Park Won Jo , Huh Sun Chul , Park Sung Ho , Song Hong Tae
Published: March 2009

SiC materials have excellent high temperature strength, low coefficient of thermal
expansion, good resistance to oxidation and good thermal and chemical stability etc. In this study,
monolithic liquid phase sintered SiC (LPS-SiC) was made by hot pressing method with nano-SiC
powder an average particle size is 30nm and less. Alumina (Al2O3), yttria (Y2O3) and silica (SiO2)
particles were used for sintering additives. To investigate effects of SiO2, Al2O3/Y2O3 composition
was fixed and then ratios of SiO2 were changed as seven kinds. Materials have been sintered for 1
hour at 1760, 1780 and 1800 under the pressure of 20MPa. The system of sintering additives
which affects a property of sintering as well as the influence depending on compositions of sintering
additives were investigated by measurement of density, mechanical properties such as Vickers
hardness and sliding wear resistance were investigated to make sure of the optimum condition which
is about matrix of SiCf/SiC composites. The abrasion test condition applies to load of 20N at 100rpm
for 20min. Sintered density, abrasion property of fabricated LPS-SiC increased with increasing the
sintering temperature. In case of LPS-SiC with low SiO2 content, has very excellent wear resistance.
Blast Performance and Its Assessment on Excavation Damaged Zone of Anisotropic Rock
Authors: Sun Huo Ran , Wang Shu Hong , Xu Shuai , Chen Wen Lin
Published: March 2009

The 290 level cave is situated in Nanfen Surface Mine, Liaoning, China. Nanfen surface
mine is one of the biggest iron ore in Benxi Iron Company. The base line of the pit bottom has
reached 346m level in Nanfen surface mine. The importance of in situ assessment of stability of the
290 level cave for next mining design and construction has been met. Investigation at the Nanfen
Surface Mine has shown that damage exists around 290 level cave and that the damage develops
from the energy imparted to the rock by the excavation method and by redistribution of the in situ
stress field around the 290 level cave. Subsequent near-by excavations, removal of loose material
from the existing cave and pore pressure changes will all influence the development and extent of
rock damage, as does the rock type and its fabric. Based on the engineering characters and rock
mechanics, the main characteristics of stress induced brittle failure of the site are introduced.
Various evaluation and measures are sought to stabilize the over-stressed rock mass. The induced
anisotropic damage process was modeled. The major results from numerical analysis of the cavern
are presented and validated by direct comparison with actual monitoring data. Next, an optimization
study was conducted with the experimentally validated and adjusted mathematical model, measured
with a recorder within such a cave. And the stability of the 290 level cave in Nanfen Surface Mine
was analysis. As a result, the model is expected to be a useful tool for simulation, design, and
optimization of pasteurization tunnels. A suitable support measure was proposed and taken.
Experimental Investigations of Thermal Damage for Rocks
Authors: Xi Dao Ying , Xu Song Lin , Tao Yue Zhan , Li Ting
Published: March 2009

As the rocks were composed of many minerals, high temperature might lead to the
non-consistent deformation among these components. That was the mechanism of thermal damage.
In the present paper, the thermal damage of rocks was investigated under a much broader
temperature range until minerals phase transition. The experimental techniques of AE and the
internal friction were proven to be the most useful tools to reveal the thermal damage. The affection
of thermal damage to Kaiser Effect of temperature and the coupled effects of thermal and
mechanical damage were also discussed.
Fracture Study on Mode I-III Crack of Rock
Authors: Li Li Yun , Xu Feng Guang , Xie He Ping , Ning Wei
Published: March 2009

This paper illustrates some preliminary experimental, numerical and theoretical analysis
results of mixed mode I-III rock cracks under apparent mode III loading. Some edge notched
granite specimens are tested under out-of-plane four-points shearing loading condition, i.e., an
apparent mode III loading condition. A series finite element analysis was conducted to understand
the mechanism of the crack fracture propagation under this loading condition. The stress intensity
factor distributions along the 3-D crack tips are also obtained. All crack fracture propagation
surfaces of the specimens are similar helicoids which radius can be mainly influenced by the
loading patterns, i.e., the action width s. The crack fracture initiates at the midpoint of the crack
front. From the numerical calculation and experimental investigation, it has been revealed that all of
these crack fracture initiations are caused by maxima tensile stress σ1. Based on this stress σ1, a new
fracture criterion of mixed mode I-III is proposed. Its predictions agree well with the experiment
results. This criterion can be applied to practice engineering designs which are related with mixed
mode I-III or pure mode III rock crack fracture problems.
Compressive Failure of Carbon/Epoxy Laminate Composites under High Impact Loading
Authors: Zhou Wei , Cao Mao Sheng , Jin Hai Bo , Lei Yi Long , Rong Ji Li
Published: March 2009

The effect of strain rate on the dynamic compressive of carbon/epoxy composite materials
was investigated via the split Hopkinson pressure bar (SHPB) technique. The specimens were tested
in the thickness, as well as in the in-plane direction at different high strain rates. The macro- and
micro-fracture morphology of the damaged laminated specimens was obtained utilizing the scanning
electron microscope (SEM). The experimental results showed that the compressive properties could
be significantly affected by the strain rates. The compressive strength and the ultimate strain in the
in-plane direction were obviously lower than that in the thickness direction. As the strain rate
increased, the laminate had not enough time to respond, the splitting failure of 0° ply of laminates
loaded in-plane along 0° was firstly found, then interfacial crack and delamination were induced, the
specimens were crushed to fragments at the highest strain rate. No obvious damage of laminates
loaded through the thickness could be observed at strain rate below 2000 s-1. The main way of the
dynamic compressive failures through the thickness was shear failure due to the brittle fracture of
the fiber at 2260 s-1.
Dynamic Fatigue Characteristics of Electrorheological Fluids: Experimental Results
Authors: Choi Seung Bok , Sung Kum Gil
Published: March 2009

In this study, the dynamic fatigue characteristics of chemical starch-based ER fluid are experimentally investigated. A flow mode type apparatus is manufactured to activate the flow motion of the ER fluid. After evaluating the field-dependent Bingham property, three important dynamic fatigue characteristics; yield stress, current density and response time of the ER fluid are investigated as a function of the operating cycle. The dynamic operation for the flow motions is undertaken up to one million cycles and electric voltage is applied to the electrodes. In addition, the change of the particles of the ER fluid is microscopically observed to advocate the variation of the yield stress.
Treatments with Fracture Mechanics in Debonding of FRP-Strengthened Concrete Beams
Authors: Li Hong Nan , Zhou Ying Wu , Wang Su Yan , Yang Mei
Published: March 2009

External bonding fiber reinforced polymers (FRP) to the tension faces of reinforced
concrete (RC) beam as an effective approach of rehabilitation and strengthening of reinforced
structures have attracted significant interests of researchers in the past decade. Since the
load-carrying capacity of RC beams strengthened with the FRP is dominated by interfacial
delaminated failure, the anchorage strength in FRP to concrete bonded joints under shear and the
debonding stress transferring behavior at the end parts of flexural concrete members bonded with
FRP have been deeply studied. Recently, methods of fracture mechanics have been introduced into
analyzing the above issues. Compared with the traditional methods, the analytical models of
existing fracture mechanics are reviewed and analyzed. Based on them the debonding bearing
capacity of FRP-strengthened RC beams is calculated and the corresponding finite element models
are created. These models of fracture mechanics are then evaluated with the finite element results
and the experimental data from author’s and the literature. Some conclusions with engineering
significance are drawn.
Ultrafine Oxides during Detonation Expanse at A Fast Quenching Rate
Authors: Li Xiao Jie , Xie Xing Hua , Zou Long Jiang , Yan Hong Hao , Qu Yan Dong , Xu Qiang , Ouyang Xin
Published: March 2009

Nanostructured spherical lithium manganese oxide (Li-Mn-O) with about 30nm in
diameter was synthesized for the first time by explosive method. The water-solubility explosive was
prepared using a simple facility at room temperature. The growth of lithium manganese oxides via
detonation reaction was investigated with respect to the presence of an energetic precursor, such as
the metallic nitrate and the degree of confinement of the explosive charge. The detonation products
were characterized by scanning electron microscopy. Powder X-ray diffraction and transmission
electron microscopy were used to characterize the products. Lithium manganese oxides with
spherical morphology and more uniform secondary particles, with smaller primary particles of
diameters from 10 to 50 nm and a variety of morphologies were found. Lithium manganese oxides
with a fine spherical morphology different from that of the normal is formed after detonation wave
treatment due to the very high quenching rate. It might also provide a cheap large-scale synthesis
method. Explosive detonation is strongly nonequilibrium processes, generating a short duration of
high pressure and high temperature. Free metal atoms are first released with the decomposition of
explosives, and then theses metal and oxygen atoms are rearranged, coagulated and finally
crystallized into lithium manganese oxides during the expansion of detonation process. For
detonation of the water-solubility explosive, the detonation pressure, the detonation temperature and
the adiabatic gamma were close to 3 GPa, 2300 K and 3. The inherent short duration, high heating
rate (1010 – 1011 K/s) and high cooling rate (108 – 109 K/s) prevent the lithium manganese oxides
crystallites from growing into larger sizes and induce considerable lattice distortion.
Study on the Crack-Tip in the Pressure-Sensitive Dilatant Materials
Authors: Yang Yong , Tang Li Qiang , Li Yong Dong
Published: March 2009

In the petroleum engineering, the nonlinear bulk strain or bulk strain rate must be
considered in rock deformation, adopting the viscous-elastic theory, a constitutive equation of the
pressure-sensitive dilatant materials was established. The governing eqations were deducted in
crack-tip field of quasi-static growing crack in pressure-sensitive dilatant materials. And for the
mechanical model of a rigid-viscoelastic material interfacial crack, through numerical calculate, the
asymptotic solution of the continuous separate variable formal of stress, strain and displacement.
The significance of the material parameter in the crack-tip field is discussed. The study of the paper
will provide theoretical references for preventing the glide of the mud rock and reducing the arises
of the failure of casings of well.
Failure Analysis of the Stochastic Structural System
Authors: Yan Xin Chi , Hua Yuan
Published: March 2009

Because there were many random factors, the failure analysis and reliability analysis of
stochastic structural system was very difficult. In this paper, failure procedure and reliability
analysis flow chart of stochastic structural system based on stochastic finite element were present.
Establishment of the safety margin, reduced member stiffness matrix and opposite sign of the
equivalent nodal force was analyzed in the failure process. Stochastic finite element method was
adopt to solve the structures’ stochastic, and the reliability of structural system is evaluated by
PNET method. According to probabilities of the failure paths redound to probability of failure of the
structural system, the most significant failure paths was determined on the basis of the
branch-and-bound method. Then, a classical 48-bar space truss problem is made as an example to
illustrate the predominance of this algorithm, the calculation shows that the analysis of the failure
process is justified; this methodology is efficient and useful for reliability analysis of large
stochastic structural system.
Numerical Analysis on Fatigue Failure of Sleeve in Oil-Film Bearing
Authors: Wang Jian Mei , Huang Qing Xue , Zhao Chun Jiang , Ma Li Feng
Published: March 2009

To solve the three-segment loop-like damage of sleeve under rolling load case, to quantitatively analyze bearing failure mechanism, a mathematical model of oil-film bearing for producing the 3-D contact pressure and shear stress distribution between sleeve and roll neck was developed by 3D elastic contact boundary element method. Some programs for automatically creating 3-D surface grid model have been developed to check data and display deformation, as well as to plot the deformation fields of roller and sleeve. Analytical results provide an effective way to decrease wear and adhesive damage of sleeve, and help to increase the load capacity of oil-film bearing and service life as well.
An Experimental Study on the Axial Collapse Characteristics of Hybrid Side Member
Authors: Lee Kil Sung , Im Kwang Hee , Yang In Young
Published: March 2009

The purpose of this study was to develop lightweight hat shaped section side members
which absorb the most of the energy during the front-end collision of vehicle. The hybrid side member
was manufactured by combination of aluminum and CFRP. An aluminum or CFRP (Carbon Fiber
Reinforced Plastics) member is representative lightweight materials but its axial collapse mechanism
is different from each other. The aluminum member absorbs energy by stable plastic deformation,
while the CFRP member absorbs energy by unstable brittle failure with higher specific strength and
stiffness than those in the aluminum member. Based on the respective collapse characteristics of
CFRP side and aluminum members, the hybrid side members were tested on the axial collapse loads
to get a synergy effect when the member is combined with the advantages of each members, such as
energy absorption by the stable folding deformation of the aluminum member and by the high specific
strength and stiffness of the CFRP member. Energy absorption capability and collapse mode of the
hybrid side members were analyzed.
Improved Damage Model of 2-D Delamination
Authors: Yang Gang , Zhang Ai Feng , Hu Wei Ping , Huang Bao Zong
Published: March 2009

This paper proposes an improved damage model and derives the shear correction factors for the model based on the Whitney[1] method. As the model is mainly used in the delamination front, the overly strong assumptions for geometric deformation in this region may be relaxed so that more realistic displacement fields can be established.
An Investigation on Piston Pin Seat Fatigue Life on the Mechanical Fatigue Experiments
Authors: Liu Yong Qi , Wang Yan Xia , Men Xiu Hua , Lin Feng Hua
Published: March 2009

Mechanical fatigue experiments are performed for piston pin seat, and the stress-strain
response of the piston overall structure is analyzed by the elastic-plastic FEA. An estimated formula
of the fatigue life is put forward by amending the Manson-Coffin formula on the basis of studying the
fatigue behavior of piston pin seat. The Newton iterative algorithm is applied to calculate the
modified formula, and the mechanical fatigue life of piston pin seat is obtained. By comparison the
predicted value with the experimental results, the feasibility of estimated formula is validated.
Fracture Parameters and Post-Peak Behavior Evaluation under LEFM on Bonded Cement-Based Materials
Authors: Park Cheol Woo , Lange David A.
Published: March 2009

Fracture of bonded cement based materials is complicated due to not only bonding itself but also heterogeneous genuine nature of cement-based materials. This study investigates the fracture parameters that obtained from the mechanical fracture tests and the post-peak behavior of bonded cement-based materials. Fracture parameters were analyzed such as the critical stress intensity factor, the critical crack length and the critical crack tip opening displacement. In addition, this study defines a new fracture parameter, the critical crack opening angle, which describes a crack opening resistance. In order to evaluate the fracture energy of quasi-brittle materials, it is typical to use the non-linear elastic fracture mechanics approaches. From the test results, however, it is known that the toughening action at the fracture process zone of the bonded interface has been significantly diminished because of the brittle fracture and the pre-determined weak crack path. Therefore, the post-peak behavior could be successfully estimated by using the suggested model that considered only the elastic deformations.
Failure Analysis of Adhesively Bonded Single Lap Joints Embedded with Metal Component as Part of Fillet
Authors: You Min , Zheng Yong , Zheng Xiao Ling , Yan Zhan Mou , Li Zhi
Published: March 2009

In order to understand the effects of the metal components embedded in adhesive fillets
on the strength of adhesively bonded single lap joint, the failed surfaces were studied with diagrams
of scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR) spectrometer. The
stress distribution along the length of the bondline of single lap steel joints was also studied with an
elasto-plastic finite element analysis (FEA) model to understand its effect in the view of mechanics.
The SEM images and the FT-IR spectra diagrams revealed that the failure in the interface was
primarily mixture mode with fillets and they also presented the interface strength being higher and
there were more polar links formed in the adhesive fillets with metal components. The result
obtained from the numerical modeling is in compliance with it from experiment that the stress
distributed in lap zone of the joint is gentler when a couple of steel wires embedded in fillet.
Multiaxial Fatigue Damage Models
Authors: Shang De Guang , Sun Guo Qin , Deng Jing , Yan Chu Liang
Published: March 2009

Two multiaxial damage parameters are proposed in this paper. The proposed fatigue damage parameters do not include any weight constants, which can be used under either multiaxial proportional loading or non-proportional loading. On the basis of the research on the critical plane approach for the tension-torsion thin tubular multiaxial fatigue specimens, two multiaxial fatigue damage models are proposed by combining the maximum shear strain and the normal strain excursion between adjacent turning points of the maximum shear strain on the critical plane. The proposed multiaxial fatigue damage models are used to predict the fatigue lives of the tension-torsion thin tube, and the results show that a good agreement is demonstrated with experimental data.
Non-Linear Fracture Mechanics Analyses of Vibrating Screen Arthropleure
Authors: Sun Huer
Published: March 2009

The dynamic properties of the model of vibrating screen are obtained using the software
Pro/ MECHANICA. The natural frequencies and mode shapes of the screen are calculated, and the
distribution law of dynamic stress is found out. It shows that the structure design of the screen is
reasonable. Under the working conditions designed, its dynamic strength is satisfied. This paper
provides engineering estimates of non-linear fracture mechanics parameters for vibrating screen
arthropleure cracks, subject to alternate stress and Vibrating. Solutions are given in the form of two
different approaches.
Fatigue Life Estimating Method for Multiple-Site Structure
Authors: Long Li Ping , Zhang Jian Yu
Published: March 2009

Fatigue crack initial life of multiple-site structure is described as the shortest life of all
site’s fatigue initial lives. This paper will establish a method, which is described to estimate fatigue
initial life of multiple-site structure. Using finite element method (FEM), the local stress
concentration of each site is calculated. Using the statistical fatigue theory, the fatigue crack initial
probability can be considered. Numerical example indicates: fatigue crack initial life of multiple-site
structure is shorter then the life of single site. At the end of paper, experiment was executed adopting
the same fatigue cycle loads with the computational case. The receivable relative error between the
experimental result and the result of numerical analysis verifies the efficiency of this
method.Introduction