bluuebunny/crossref_metadata_2025 huggingface dataset:
Water Thickness Gaging in a Bellows Tube Using Special UT Shoes & an Immersion Ultrasonic System
Authors: Koo Kil Mo , Kim Sang Baik , Lim In Chul , Sim Chul Moo , Cheong Yong Moo , Park Chi Seong
Published: March 2009

In this experiment, a residual water level gaging in a bellows tube is implemented by
appling the immersion ultrasonic technique. The bellows tube is located in a complex structure. Since
it is located at considerable depth implemented, it is difficult to approach it from the outside working
area, which has a residual water level after a drainage of the water in it, because a structure like the
bellows has a peak and mold shape.
Evaluation of the Ductile-Brittle Transition Behaviour of Aging Specimens by the Fracture Toughness Test
Authors: Kim Hyung Ick , Huh Yong , Park Jae Sil , Seok Chang Sung
Published: March 2009

The safety and reliability of industrial machineries and structures used in various, and
severe conditions has become an increasing concern. This study proposes ductile-brittle transition
temperature (DBTT) evaluation technique by the sub-sized specimen test to prevent cleavage
fracture. Four classes of the thermally aged 1Cr-1Mo-0.25V specimens were prepared. The fracture
toughness tests were performed on sub-sized specimens both at room and low temperatures. The
results of the fracture toughness tests were analyzed to obtain the DBT behaviours of the specimen
materials
Fatigue Crack Propagation Life of Welded Joints Related to the Statistical Characteristics of Multiple Surface Cracks
Authors: Han Jeong Woo , Han Seung Ho
Published: March 2009

Multiple collinear surface cracks distributed that are randomly along a weld toe have a
strong influence on the fatigue crack propagation life of welded joints. This issue is investigated using
statistical approaches based on series of systematic experiments, in which initial crack numbers, their
locations and crack sizes, i.e. depth and length, are taken into account. The number of initial cracks
follow a normal distribution, and the probability of initial crack depths and lengths can be accurately
described by the Weibull distribution. These characteristics are used to calculate the fatigue crack
propagation life, in which the mechanisms of the mutual interaction and the coalescence of multiple
cracks are considered as well as the Mk-factors. The automatic calculation of fatigue crack
propagation life is achieved by the application of NESUSS, where parameters such as the number,
location and size of cracks are all treated as random variables. The random variables are dealt through
a Monte-Carlo simulation with sampling random numbers of 2,000. The results of the simulation
provide the statistical characteristics of the fatigue crack propagation life for welded joints as a
function of the number of initial cracks. The sum of the simulation results and the fatigue crack
initiation life referred from a previous paper is in good agreement with the experimental results.
Failure Analysis of Railway Wheel Tread
Authors: Kwon Seok Jin , Lee Dong Hyung , Kwon Sung Tae , Goo Byeong Choon
Published: March 2009

The majority of catastrophic wheel failures are caused by surface opening fatigue cracks
either in the wheel tread or wheel flange areas. The inclined cracks at railway wheel tread are initiated
and the cracks are caused by wheel damage-spalling after 60,000 km running. Because the failured
railway wheel is reprofiled before regular wheel reprofiling, the maintenance cost for the railway
wheel is increased. Therefore, it is necessary to analyze the mechanism for introduction of crack. In
the present paper, the combined effect on railway wheels of a periodically varying contact pressure
and an intermittent thermal braking loading is investigated. To analyze damage cause for railway
wheels, the measurements for replica of wheel surface and effect of braking application in field test
are carried out. The result shows that the surface cracks in railway wheel tread are due to combination
of thermal loading and ratcheting.
Experimental Study of High-Velocity Impact Characteristic of Mg Alloy Using Ballistic Range
Authors: Hwang Do Yeon , Shimamoto Akira , Numata Daiju , Kikuchi Takamase , Takayama Kazuyoshi
Published: March 2009

In this study, dynamic penetration phenomena of high-velocity impact of magnesium alloy
were investigated. The surface hardness of magnesium alloy (AZ31B-O) and the heat-treated
magnesium alloy (AZ31B-200°C, AZ31B-300°C, and AZ31B-430°C) were examined using Micro
Vickers, and the influence of the heat treatment temperature was observed. We analyzed the metal
organization using a microscope. We also used a ballistic range (two-stage light gas gun), and the test
specimens were set at 0°obliquity at room temperature. A high-speed camera allowed us to capture
and analyzed the dynamic penetration phenomena of the test specimen.
Residual Stress Evaluation and Its Effects on the Fatigue Life of an Autofrettaged Tube
Authors: Koh Seung Kee
Published: March 2009

The theoretical residual stresses in the autofrettaged tube were calculated, considering
Bauschinger effect caused by the reverse yielding while removing autofrettage pressure. Actual
residual stresses were measured by using X-ray diffraction analysis, and compared with the
theoretical calculations. From the tension-compression tests, however, the tube steel showed a
significant Bauschinger effect, depending on the plastic strain prior to unloading. Fatigue crack
growth life of the tube was evaluated by integrating the crack growth rate equation. Stress intensity
factor of an inside crack at the tube due to pressure and residual stresses was determined from finite
element analysis and superposition principle. Compared to the unautofrettaged tube, the extended
fatigue life of the autofrettaged thick-walled tube was obtained depending on the autofrettage level
and the Bauschinger effect.
Anti-Fatigued Criterion of Annularly Breached Spindle on Mechanical Design
Authors: Li You Tang , Ma Ping , Yan Chang Feng
Published: March 2009

The anti-fatigued design is an important field in product lifecycle management. A uniform
criterion of annularly breached spindle was put forward in this paper. The crack, V-notch, U-notch
and arc were described as breach uniformly according to the tip radius, depth and field angle of breach
in the method. The connection between sharp V-notch and crack, between V-notch and U-notch has
been set up. We fuse the fatigue fracture theory and life prediction techniques together on the design
technology of lifecycle safety guarantee of mechanical structures. The relationship between life and
detectability of the breached spindle system was discussed to provide useful guidance for practical
applications. The criterion for the safety design and fracture design both of which on fα was obtained.
The criterion of annular breached spindle under torsion was obtained at first and then the effects of
bending to lifecycle of spindle were analyzed.
Time Reversal Technique for Ultrasonic Guided Wave Inspection
Authors: Kim Hak Joon , Song Sung Jin , Seo Jung Ho , Kim Jae Hee , Eom Heung Seop
Published: March 2009

For the long range inspection of structures in nuclear power plant using array transducers, it
is necessary to focus waves on defects under interrogation. To take care of such a need, in this study
we adopt a time reversal technique that is claimed to be very robust to focus ultrasonic waves on
defects. Specifically, we calculate the appropriate time delay using the time reversal technique and
re-generate ultrasonic guided waves that are focusing to an interrogated defect with the calculated
time delay. In this paper, we describe the principle of the time reversal technique briefly and present
the performance enhancement obtained by the time reversal techniques.
Influence of the Thickness of the Specimen in the Infrared Hybrid Method in Consideration of Heat Conduction
Authors: Machida Kenji , Miyagawa Shohei
Published: March 2009

The thickness dependency of the temperature image obtained by an infrared thermography was investigated using specimens with three kinds of materials and four kinds of the thickness of the specimen. Then, the infrared hybrid method was developed to separate individual stress components. However, it had the influence by heat conduction in the infrared stress measuring method. Therefore, an error will occur in the infrared hybrid analysis. Then, the system which corrected the error by the inverse analysis was developed. Thereby, the accuracy of the stress intensity factor was able to be raised. Furthermore, the accuracy of hybrid method considering to heat conduction was discussed in comparison with the 3-D finite-element analysis and 2-D hybrid method.
Modeling of Ultrasonic Wave Propagation Path through Cancellous Bone and Quantitative Estimation of Bone Density and Bone Quality
Authors: Otani Takahiko
Published: March 2009

Osteoporosis is a disease characterized by decreasing bone density, and is assessed by the
bone mass density of cancellous bone. An X-ray method is widely used for noninvasive measurement
of bone mass density [mg/cm3]. An ultrasonic method has the potential to evaluate the elastic
properties, however measured ultrasonic parameters are the slope of frequency dependent attenuation
(BUA [dB/MHz]) and the speed of sound (SOS [m/s]), not the bone mass density [mg/cm3]. In
previous study, two longitudinal waves, the fast and slow waves, were observed in cancellous bone. In
this study, the propagation path through cancellous bone is modeled to specify the causality between
ultrasonic wave parameters and bone density. Then bone density and bone elasticity are quantitatively
formulated. A novel ultrasonic bone densitometry, prototype LD-100, have been developed. The bone
density [mg/cm3] and the bone elasticity [GPa] are evaluated by ultrasonic parameters based on the
fast and slow waves in cancellous bone using a modeling of ultrasonic wave propagation path.
Ultrasonic Inspection of Carbon/ Phenolic Composites Using a Peak-Delay Measurement Method
Authors: Yang In Young , Im Kwang Hee , Hsu David K. , Song Sung Jin , Cho Hyeon , Kim Sun Kyu , Seo Young Hwan , Park Je Woong
Published: March 2009

Carbon/phenolic composite (CPC) materials are unique which consist of carbon fibers
embedded in a carbon matrix. The CPCs are originally developed for aerospace applications and its
low density, high thermal conductivity and excellent mechanical properties at elevated temperatures
make it an ideal material for aircraft brake disks. The properties of the CPC are dependent on the
manufacturing methods used for production and fiber arrangement. It is desirable to perform
nondestructive evaluation to assess material properties and part homogeneity in order to ensure
product quality and structural integrity of CPC brake disks. In this work, a CPC material was
nondestructively characterized and a technique was developed to measure ultrasonic velocity in C/P
composites using automated data acquisition software. Also a motorized system was adopted to
measure ultrasonic velocity on the point of CPC materials under the same coupling conditions.
Manual results were compared with those obtained by the motorized system with using drycoupling
ultrasonics and through transmission method in immersion. A peak-delay measurement
method well corresponded to ultrasonic velocities of the pulse overlap method and throughtransmission
mode and C-scan image signal based on peak-to-peak amplitude.
Effective Flexibility Calculation for Beams with Periodic In-Homogeneities
Authors: Chung Il Sup , Chai Young Suck
Published: March 2009

Analysis of structures including periodically arrayed in-homogeneities, whether they are microscopic or macroscopic, can be simplified by using homogenized properties. If the unit structure is repeated in a longitudinal direction, the whole structure may be regarded as a beam with effective flexibility. This study proposes a kinematical periodicity constraint to be imposed on the FE model of the unit structure for beams, which improves the accuracy of the effective flexibility along with reduction of the model size. The method is applied to a beam-in-space containing repetitive un-symmetric holes, and it is demonstrated that the deformation behavior of the homogenized beam agrees well with that of the real structure.
Carbon Nanotubes-Adsorbed Polymeric Microspheres for Electrorheological Fluids
Authors: Yoon Seok Ho , Choi Hyoung Jin , Jin Hyoung Joon
Published: March 2009

Surface-conductive microspheres consisting of poly(methyl methacrylate) (PMMA) (6.5
μm) core and carbon nanotubes (CNTs)-adsorbed shell were prepared using a simple process
involving the blending of two colloidal solution; an aqueous CNT dispersion with surfactants and an
aqueous PMMA microsphere colloid. These were adopted as the suspended particles for
electrorheological (ER) fluids, in which the electrical conductivity originated primarily from the
surface-coated conducting CNT layers. The CNT-adsorbed polymeric microspheres were
monodisperse and spherical in shape. The CNT-PMMA composite suspensions in silicone oil showed
the typical ER characteristics of forming a chain-like structure under an applied electric field. The
CNT-PMMA composite microspheres exhibited a conductivity ranging from 5.2×10-4 to 6.3×10-5
S/cm, which is an acceptable conductivity range for ER fluids. This phenomenon can be explained by
the interfacial polarizability of CNTs adsorbed on the surface of the polymeric microspheres.
Compressive Deformation Analysis of Smart Skin Structure Embedded with Round Shape Antenna
Authors: Joe June Sung , Park Hoon Cheol , Yoon Kwang Joon , Goo Nam Seo
Published: March 2009

In this paper, a smart skin, i.e. a conformal load-bearing antenna structure, which is a
multi-layer sandwich structure composed of carbon/epoxy, glass/epoxy and dielectric material,
designs, analyses, fabrications and tests are conducted. Mechanical properties of each structural layer
of the designed smart skin are obtained from experimental tests. Tests and analyses are conducted to
study the deformation behavior of the smart skin under compressive loads. The measured data are
compared with the numerical results from geometrically linear/nonlinear finite element analyses.
Numerical prediction for the buckling load of the smart skin agreed well with the experimental data.
Surface Roughness Measurement by Using Interferometer and Active Interferometer Stabilization
Authors: Kim Jin Tae , Kim Dohyoung , Kim Hyun Su , Park Jong Rak
Published: March 2009

The profile of the mirror surface is measured by using optical phase shift method and
Twymann-Green interferometer. Phase map is calculated by applying 4–buckets method and
Vikhagen phase shift algorithm is applied to escape convolution errors. From that the obtained
roughness of the mirror surface is around 20 nm rms roughness value. Also, the interferometer was
stabilized by using fringe locking method. Also, we propose two colors method very precise surface
profile and the length can be measured in the harsh environmental conditions.
Dislocation Distribution Function of the Surfaces of Mode III Dynamic Crack Subjected to Unit-Step Loads and Moving Increasing Loads
Authors: Li Xin Gang , Lü Nian Chun , Song Guo Zhi , Jin Cheng
Published: March 2009

By the theory of complex functions, dislocation distribution function concerning mode
dynamic crack propagation problem under the conditions of unit-step loads and moving increasing
loads was studied respectively. Analytical solution representations are attained by the methods of
self-similar functions. The problems investigated can be transformed into Riemann-Hilbert problems
and their closed solutions are obtained rather simple by this approach.
Numerical Investigation on the Crack Propagation in a Flat Stiffened Panel
Authors: Nobile Lucio , Lamanna Giuseppe , Soprano Alessandro
Published: March 2009

This work is focussed on the numerical prediction of the fracture resistance of a flat fullscale aluminium alloy 2024 T3 stiffened panel under monotonic traction loading condition. The numerical simulations are based on the micromechanical Gurson-Tvergaard (GT) model for ductile damage. The applicability of the GT model to this kind of structural problem has been studied and assessed by comparing numerical results, obtained by using the WARP 3D finite element code, with experimental data provided from literature.
Prediction of Crack Propagation under Dynamic Loading Conditions by Using the Enhanced Point Collocation Meshfree Method
Authors: Kim Hyo Jin , Lee Sang Ho , Kim Moon Kyum
Published: March 2009

An efficient and accurate numerical program with enhanced point collocation meshfree
method is developed to simulate crack propagation under dynamic loading conditions. The enhanced
meshfree method with point collocation formulation and derivative approximation in solids is
presented. This study also presents the crack propagation criterion and computation of propagating
direction, and the total structure of the numerical program named PCMDYC(Point Collocation
Meshfree method for DYnamic Crack propagation). Several examples of crack propagation under
dynamic loads are analyzed to simulate the arbitrary crack propagation under dynamic loads. The
results show that PCMDYC predicts the propagating path of crack under dynamic loading conditions
accurately and robustly.
Fracture Initiation and Propagation in Fatigue Contact Loading of AA6082 Aluminium Alloy
Authors: Benedetti Angela , Molari Pier Gabriele , Morelli Piero
Published: March 2009

This paper presents the results of an experimental investigation on surface contact fatigue of AA6082 aluminium alloy. After testing, microscopy analysis of the specimen contact area shows plastic deformation at the centre and circumferential cracks at the very edge of the print. Major cracks develop at a certain depth under the border of the contact area and propagate beneath the surface, in the direction of both the centre of contact and the lateral free edge of the specimens. No cracks have been observed at the centre of contact, neither on the surface, nor inside the material. Tensile properties of the alloy have been measured and a non linear finite element analysis has been performed in order to calculate the field of deformation and stress in the contact zone. Finally, stress intensities are correlated with the crack initiation points and an interpretation of the propagation paths, in regard to stress distribution, is given.
Relaxation Analysis of Bolt Load in Single Bolted Joints Fastening Thermosetting Polymer
Authors: Lee Sang Soon , Kim Noh Yu
Published: March 2009

The boundary element analysis is attempted to investigate the relaxation behavior of the
bolt load in a single bolted joint fastening thermosetting polymers. More than 10 % relaxation is
obtained after 4,000 minutes. The loss of bolt stress is more important because the stress in the
polymer is much smaller. Such relaxation of the bolt stress can cause loosening for fasteners and loss
of fastener effectiveness for bolts that rely on clamping force or preload to achieve needed joining
forces. The experimental evaluation is required to clarify the effect of the loss of bolt load on function
of the assembly.
Fatigue Life Evaluation for Notched Components of Automatic Transfer Devices
Authors: Choi Young Woo , Noh Byeong Wook , Ham Kyung Chun , Bae Sung In
Published: March 2009

In this study, the fatigue life evaluation of automatic transfer devices under stress
concentrations due to the notch effect is performed. To investigate residual life of a notched
component, load histories were obtained through strain measurement. A fatigue test was performed
on a specimen imitating a real component and results were compared with each notch root radius of
the concentration area. Three-dimensional finite element analysis was also performed to evaluate the
local stress fields. Miner’s rule was used to predict the fatigue life calculation. As a result, the
predicted life of a notched component was in good agreement with a real component and introduced a
special method for measuring load using real machine components.
Real-Time Monitoring and Simulating the Load Effects of Smart” CFRP- Strengthened RC Beams
Authors: Lu Shao Wei , Xie Huai Qin
Published: March 2009

FBG sensors have excellent compatibility with CFRP sheets. It can be embedded into
CFRP sheets to fabricate the “smart” CFRP. This paper conducted 4 pieces of CFRP-strengthened
RC beams, and embedded FBG sensors and strain gauges on the steel, concrete and CFRP of RC
beams. The simulation program of flexural load effects of RC beams is compiled based on the theory
of reinforced concrete and ANSYS. The experimental results show that during the load bearing
process: the compatibility is perfect between FBG sensor and CFRP; the linear relationship of FBG
sensor and strain gauge is uniform; the numerical simulation results and the measuring results of
strains of tensile steel and compressive concrete, the load agree well. So utilizing the smart CFRP
strengthened RC structures can realize the dual function of advanced rehabilitation and real-time
health monitor and evaluation.
Forced Response of Harmonic Mistuned Blade Disks
Authors: Lee Kuang Chyi , Li Kuang Chih , Yu Hsin Her , Lin Chien Chang
Published: March 2009

In this paper, by adopting the continuous ring model and the perturbation analysis for free
vibration, the authors showed the reason and the importance for the modes split phenomena and
provided the qualitative relation between modes split and perturbation for the harmonic number of
stiffness perturbation. Also through the modal analysis for forced vibration the authors showed
possible ways to predict and prevent the worst case when blade will crack. That is, the harmonic
number for stiffness distribution should be avoided to be twice the engine order.
Temperature Effect on Yield Stress of Electrorheological Fluids: Experimental Investigation
Authors: Choi Seung Bok , Sohn Jung Woo , Lee Y.S.
Published: March 2009

In the present paper, temperature effect on yield stress of electrorheological fluids is
experimentally investigated. A rotational shear-mode type electroviscometer is designed and
manufactured for the identification of Bingham characteristics of ER fluids. Optimization of ER
fluids is undertaken with carrier liquid, particle and additive treatment and then four different ER
fluids are prepared for the test. The field-dependent yield stress, current density and response time
of optimized ER fluids are compared at various temperature conditions.
Study on the Mechanism about the Effect of Technological Parameters on Performance of Fiber Coupler
Authors: Shuai Ci Jun , Duan Ji An , Zhong Jue
Published: March 2009

To find out the effect mechanism of technological parameters on the performance of
fiber coupler, the relationship between the technological parameters and the optical performance is
investigated by using a six-axes optical fiber coupler machine as experimental setup. It is discovered that
the technological parameters such as drawing speed and fused temperature have a great effect on
optical performance of fibre coupler. The fused region and taper region of fiber coupler are tested
with scanning electron microscope (SEM). It is discovered that there are crystalline grains in the
fused region. And the crystalline grains decrease while drawing speed increase. In the taper region,
there are micro cracks. And the cracks are more obvious while drawing speed increases. When the
fused temperature is above some point (here is 1350), the micro cracks in the taper region
disappear and the optical performance of fiber coupler is the highest at this time.
Investigation into the Dynamic Fracture Properties of Large Scale Functionally Graded Materials
Authors: Yang Xiao Bin , Zhuang Zhuo , Yao Xue Feng
Published: March 2009

A crack propagation perpendicular to gradient in a large scale functionally gradient
materials, which has (1) a linear variation of Young’s modulus with a constant mass density and
Poisson’s ratio, and (2) a exponential variation of Young’s modulus with a constant mass density
and Poisson’s ratio, is modelled by finite element methods. Based on the experimental result of
large scale functionally gradient materials, the dynamic propagation process of the FGMs is
modelled and the dynamic parameters, like the energy release rate and crack tip opening angle, are
calculated through a generation phase.
Size Effect and Microscopic Experimental Analysis of Copper Foils in Fracture
Authors: Wang Huai Wen , Ji Hong Wei
Published: March 2009

In this paper, the size effect of thickness on fracture toughness in the fracture behavior of a kind of copper foils was studied experimentally and analytically. Copper foil specimens with thicknesses ranging from 0.02mm to 1mm were adopted. The fracture toughness defined as the value of the critical J integral at cracking initiation was shown to depend on foils’ thickness within a certain range of thickness. For elucidating the relationship between fracture toughness and thickness, microscopic experimental analysis was carried out. Metalloscope results also showed that microscopic structure of different specimens with different thicknesses is also a factor affecting the fracture toughness. In order to explore the effect of pure thickness on fracture, specimens with the same microscopic structure were also investigated.
Prediction of Mixed Mode Crack Propagation Direction in Carbon Fiber Reinforced Plastic Plate
Authors: Zhang Shao Qin , Li Jun Lin , Yang Wei Yang
Published: March 2009

A newly developed Z-fracture criterion is introduced in this paper by introducing the new
concepts of in-plane dilatational strain energy density factor, in-plane average strain and reciprocal
function. The Z-fracture criterion is applied to predict the mixed mode crack propagating direction
in carbon fiber reinforced plastic (CRP) plate. The test results show that the Z-fracture criterion can
be successfully used to predict the mixed mode crack propagation direction in CRP plate.
Effect of Transverse Shear on Deformation of Thick Laminated Sandwich Plates
Authors: Gordnian K. , Hadavinia H. , Karwatzki J.
Published: March 2009

The effect of transverse shear on the deformation of thick laminated sandwich plates under
cylindrical bending is studied, based on the first order shear deformation theory (FSDT) with the
application of shear correction factor (SCF). It is shown that depending on the mechanical and
geometrical properties of the layers, the contribution of the transverse shear stress to the maximum
deflection of the plate is variable and in some cases accounts for up to around 88% of the total
deflection. The analytical results are compared and verified with finite element analysis.
Fracture Strength and Damage Resistance of Freeze Cast Alumina/Zirconia Layered Composites
Authors: Lyu Seung Woo , Han Dae Seok , Park Young Min , Yang Tae Young , Lee Jae Myung , Park Hong Chae
Published: March 2009

Symmetric three-layer Al2O3/ZrO2 composites have been prepared by freeze casting and
pressureless sintering at 1400-1600o C in air. The layered composite with Al2O3 containing 15 vol.%
ZrO2 as an outer layer and containing 20 vol.% ZrO2 as an inner layer, sintered at 1600o C showed the
maximum bend strength (300 MPa). Contact damage resistance was superior in layered composites
compared with monolithic materials, possibly due to the development of compressive stress in the
outer layer.
Accuracy of Intersection Counting Method in Measurement of Fiber Orientation Angle Distribution Using Image Processing
Authors: Kim Jin Woo , Lee Dong Gi
Published: March 2009

While mold fiber reinforced composite material to problem of occasion that high temperature compression molding, flow length in mold is overlong or when flow meets with resistance in side of mold, fiber orientation happens and big change occurs in strength or quality. Thus, in compression molding that use fiber reinforced composite material, orientation state of fiber in moldings is the most basic element that quotes various properties of matter values. Therefore, to clear orientation state of fiber establishing measurement of fiber orientation angle distribution is very important while give correction of molding condition decision, mechanical quality of moldings and guide about material design. In the study, the fiber orientation distribution of simulation figure plotted by PC is measured using image processing in order to examine the accuracy of intersection counting method. The fiber orientation function measured by intersection counting method using image processing is compared with the calculated fiber orientation function. The results show that the measured value of fiber orientation function using intersection counting method is lower than the calculated value, because the number of intersection between the scanning line and the fiber with smaller fiber aspect ratio is counted less than with larger fiber aspect ratio.
Non-Contact and Contact Ultrasonic Detection of Fiber Orientation in Orthotropic Composite Laminates
Authors: Yang In Young , Heo Uk , Lee Kil Sung , Park Je Woong , Kweon Young Sub , Hsu David K. , Cho Young Tae , Lee Chong Ho , Im Kwang Hee
Published: March 2009

Since layup orientation of the laminates greatly influences its properties, an NDE technique for layup orientation determination would be very beneficial. It is desirable to perform contact-less nondestructive evaluation to assess material properties and defects of composites because of permeation of coupling medium such as water. An ultrasonic technique would be very useful, which could be used to test the part after and before curing laminates and requires less time than the optical test. First of all, conventional ultrasonic experimentations were conducted using water as a transmitting medium. In contrast, air-coupled ultrasound is non-contact and has clear advantages over water-coupled testing. Therefore ultrasonic systems for air-coupled and conventional ultrasound were set out for different measurement modalities for acquiring ultrasonic signals as a function of in-plane azimuthal angle. Firstly, a manual scanner was built for making transmission measurements using a pair of normal-incidence shear wave transducers to find the effect of fiber misorientations of orthotropic composite laminates. With the transmitter and receiver on the same side of a laminates, Lamb waves were generated and used for the amplitude magnitude. As a result, it was confirmed that the influence of fiber direction in the laminates could be detected by the non-contacting or contacting inspection from one-side and the detectability was improved by using shaped tube for reducing the specular reflection on transmitting. Furthermore, a vector decomposition model was utilized for lay-up error of the orthotropic laminates. Finally, aircoupled results well corresponded somewhat to those of contact ultrasonic examination in the orthotropic laminates.
Research on the Crack Forming and Control of Centrifugal Cast High Speed Steel Rolls
Authors: Feng Xi Lan , Jiang Zhi Qiang , Shi Jin Fa
Published: March 2009

The effects of roll materials, mould parameter, pouring parameter and cooling parameter on the crack of high speed steel (HSS) roll fabricated by a centrifugal casting have been analyzed. The modification of HSS roll was researched. The structures and properties of HSS roll modified by potassium and rare earth were improved. The hot tearing force of modified HSS roll increased by 32.77% and reached 158N. Modification was able to decrease the line constriction. The adoption of variable speed centrifugal casting technique, variable flux pouring technique and variable speed solidification cooling technique was able to adjust the temperature field and stress field of the roll, which benefited the filling and solidification of molten steel and eliminated the crack of HSS roll.
Fracture Behavior in a Rock Pillar Subjected to Coupled Thermo-Mechanical Loading
Authors: Li Lian Chong , Tang Chun An , Lindqvist P.A.
Published: March 2009

Using RFPA code, analyses have been carried out to investigate the stability of a rock pillar
in a experiment for nuclear waste repositories, the numerically obtained stress field, temperature
distribution, failure pattern of the pillar rock and associated AE events are all agree well with the
in-situ data. Minor fracture initiation may take place in the vicinity of the boreholes after heating.
Heating induces minor spalling at central pillar wall for 0.5 m sections below the tunnel floor, but the
area of spalling is found to be limited. The core of the pillar remains intact for stress conditions
corresponding to 120 days of heating which not only prove that the proposed technique provides a
powerfully alternative and effective approach for the study on thermal-mechanical-damage coupling
mechanism but also provide meaningful guides for the experiment design and associated applications.
Effect of the Welding Heat on Fracture Toughness and Fatigue Property in a Ti-Alloy
Authors: Sun Jian Ke , Li Zhen , Li Qing Fen
Published: March 2009

Ti-alloy is widely used in engineering because it possesses excellent specific strength and
corrosion resistance. The effect of welding process on J-integral value and fatigue crack growth
(FCG) rate in a Ti-alloy is experimentally investigated in this paper. A series of test is performed
with SENB specimens for J-integral test and CT specimens for the FCG rate test respectively. Base
metal, welded joint and HAZ materials were used to make different test specimens. Results show
that the J-integral values of welded joint and HAZ are obviously smaller than those of the base
metal. And that the FCG rate value of welded joint is much higher than those of base metal and
HAZ material. It means that welding process may lead to a great reduction in fracture toughness
and the fatigue property for titanium alloy. Therefore, the inhomogeneity of the welded joint must
be considered when assess welded structures.
Fatigue Strength of Ion Nitrided Tool Steel
Authors: Zhang Mian , Nishida Shinichi , Hattori Nobusuke
Published: March 2009

The authors have studied and clarified that ion nitriding was able to improve the fatigue
properties of tool steel. Five kinds of ion nitriding methods (ion nitriding condition is different)
were used in this study. The fatigue test had been performed using a rotating bending fatigue testing
machine to investigate the effects of ion nitriding on fatigue properties of tool steel. The
fractography was analyzed using a scanning electron microscope (SEM), and hardness distribution
was also investigated using a microhardness tester. As a result, the fatigue strength and hardness of
the ion nitrided specimen increased after ion nitriding processing. It is considered that the
compressive residual stress which produced by ion nitriding processing in the layer reduced fatigue
fracture, and the altered surface composition improved surface hardness. According to the results of
the fatigue test, the optimal ion nitriding method on improving the fatigue limit of tool steel was
determined. The hardness of the specimens remarkably increased after ion nitriding processing.
Nonlinear Free Vibration for Cross-Ply Laminated Damaged Plates with Piezoelectric Actuators
Authors: Zheng Yu Fang , Fu Yi Ming , Qi Kai
Published: March 2009

On the basis of the anisotropic damage theory and piezoelectric theory, the nonlinear free
vibration governing equations for cross-ply laminated damaged plates with piezoelectric actuators
are established. The Galerkin procedure furnishes an infinite system of equations for time functions
which are solved by the method of harmonic balance. In the numerical results, the influences of
damage parameters and piezoelectric effect on the nonlinear amplitude-frequency response curves
of the laminated plates are discussed, which results reveal the inherent features about the coupled
mechanics and electricity.
Shear Failure Load of SFR-UHPCC I-Beam without Stirrup Based on Limit Analysis of Concrete Plasticity
Authors: Wu Xiang Guo , Han Sang Mook , Kim Sung Wook , Kang Su Tae
Published: March 2009

This paper concerns the theoretical research of shear failure load of steel fiber reinforced
ultra high performance cement composites (SFR-UHPCC) beam. Based on test investigation, an
analytical model of prestressed SFR-UHPCC beam is constituted. Two formulae of ultimate failure
load, i.e. the upper bound and the lower bound of shear loading capacity, all have been obtained
according to the limit analysis of concrete plasticity. In the process of upper bound analysis, uniform
distribution of steel fiber has been assumed, and virtual work induced by steel fiber has been
divided into two parts, i.e. pulling-out virtual work and debonding virtual work. Five coefficients
are introduced considering some defects. Twelve SFR-UHPCC beams with three kinds of shear span
ratio i.e. 2.7, 5.6 and 8.5 are tested and compared with the results from the proposed equations.
Sustained Loading Fracture and Strength of Concrete Modelled by Creep-Damage Interaction
Authors: Xu Tao , Lin Gao , Tang Chun An , Hu Zhi Qiang
Published: March 2009

The phenomenon creep fracture is well-known for concrete. In the present paper, the
Material Failure Process Analysis (MFPA2D) model for concrete in the failure process is coupled in
series with the time-dependence of the concrete damage and deformation. Further, the progressive
creep failure of concrete specimens under constant tensile loading was numerically simulated and the
typical time-dependent deformations: the transient creep, the steady-state creep and the accelerating
creep were also represented. The numerical simulations indicate that the macroscopic creep failure is
induced by clusters of micro-fractures on a mesocopic scale. The above numerical results offer us
some theoretical indications and instructions to further investigate the instability failure mechanisms
of engineering concrete structures in civil and hydraulic engineering.
Fracture Failure Prediction of a Mode III Crack in Orthotropic Functionally Graded Strip
Authors: Chang Jian Mei , Feng Wen Jie
Published: March 2009

Mode III fracture failure of a through crack in an orthotropic functionally graded strip is
investigated. The shear moduli in two directions of the material are respectively assumed to vary
proportionately as a definite gradient. Fourier cosine transform is used to reduce the problem to
solving a Fredholm integral equation. The crack tip stress field is obtained by considering the
asymptotic behavior of Bessel function. Energy density factor criterion is applied to obtain the
maximum of the minimum energy density and direction of crack initiation. Numerical results are
given graphically to illustrate the effects of the material property parameters and geometry criterion
on the energy density factor.
Feature Extraction for Gear Failure Detection Based on Nonlinear Mapping
Authors: Liao Guang Lan , Shi Tie Lin , Nie Lei
Published: March 2009

A general-purpose useful parameter in data analysis is the intrinsic dimension of a data
set, corresponding to the minimum number of variables necessary to describe the data without
significant loss of information. Feature extraction, including linear or nonlinear mapping technique,
is efficient to estimate the intrinsic dimension of the data set, which is a key issue to machine fault
diagnosis. This paper presents a novel application of feature extraction using the nonlinear mapping
technique called curvilinear component analysis (CCA) for gear failure detection. In the approach
high-dimensional data are nonlinearly projected toward an output space with dimension equal to the
intrinsic dimension. Hence, enough information is remained to describe correctly the original data
structure, and feature extraction based on CCA reduces dimensionality of the raw feature space for
machine failure detection. Gearbox vibration signals measured under different operating conditions
are analyzed using the technique. The results indicate that the intrinsic dimension of the data set is
estimated and a 2-D subspace is extracted by the CCA technique, then the high-dimensional
original feature data are projected into the 2-D space and form several clustering regions, each
indicative of a specific gear condition, respectively. Thus, the gear operating conditions including
normal, one cracked tooth, and one broken tooth are classified and detected clearly. It confirms that
feature extraction based on the nonlinear mapping is very useful and effective for pattern
recognition in mechanical fault diagnosis, and provides a good potential for applications in practice.
Application of the GTN Model to Quantify Constraint Effects on Ductile Fracture of API X65 Steels
Authors: Kim Yun Jae , Oh Chang Kyun , Oh Chang Sik
Published: March 2009

This paper quantifies the effects of geometry, the loading mode and the specimen size on fracture toughness of the API X65 steel, via plane strain finite element (FE) damage analyses using the GTN model. The validity of FE damage analyses is checked first by comparing with experimental test data for small-sized, cracked bar test. Then the analyses are extended to investigate the effects of the relative crack depth and the specimen size on fracture toughness. It is shown that fracture toughness of the API X65 steel increases with decreasing the relative crack depth and increasing the specimen size.
Mechanical Properties and Fracture Mechanism of TiCp/ZA-12 Composites
Authors: Xiang Wang , Xue Xiao Hua
Published: March 2009

TiCp/ZA-12 composites have been fabricated by XDTM method and stirring-casting
techniques. The tests for mechanical properties reveal that the tensile strength and strength
increase with increasing fraction of TiC particles. When the fraction of TiC particles increase up to
10%, the tensile strength and yield strength are 390MPa and 340MPa, respectively and they increase
by 11% and 17% than that of matrix respectively. From the analysis of fractography we can see that
mixed fracture of cleavage fracture and dimple fracture exists in the TiCp/ZA-12 composites, and
fractured particles are not found. Finally the fracture model of composites has been established based
on the experimental results.
Mechanical Properties and Corrosion Behavior of a Beta Titanium Alloy
Authors: Zheng Yu Feng , Wang Bao Lai
Published: March 2009

Recently, people devote to the development of beta titanium alloys which have better
biocompatibility because of the addition of Mo, Nb, Ta, Zr, Sn, et al. In this paper, the effects of
heat treatment and cold roll deformation on the mechanical properties of the Ti-11.3Mo-6.6Zr-4.3Sn
alloy (TMZS) are investigated by tensile test. The results show that the excellent combination of
strength and ductility can be obtained by heat treatment or cold deformation. The TMZS alloy can
obtain intermediate modulus, stronger than nickel titanium, weaker than stainless steel. The
corrosion resistance of this alloy in the Hank's solution, 0.9% NaCl physiological solution and
artificial saliva with different pH values at 37 are investigated by means of open-circuit potential
(OCP), Tafel and potentiodynamic anodic polarization techniques. All the test results suggest that
the TMZS alloy has excellent corrosion resistance in the three simulated solutions especially in the
artificial saliva and has a large potential for biomedical application. In addition, the pH value and
simulated solutions have some influence on the corrosion resistance of the TMZS alloy.
The Impact Damage Evolution of Steel Fiber Reinforced and Polymer Modified Concrete
Authors: Liu Yi Ping , Tang Li Qun , Huang Xiao Qing
Published: March 2009

Impact tests were carried out by use of a 74-mm-diameter split Hopkinson pressure bar to
investigate the impact damage behaviors of plain concrete (PC), steel fiber reinforced concrete
(SFRC) and steel fiber reinforced and polymer modified concrete (SFRPMC). The results show that
all three kinds of materials appear strain rate strengthening effects, and SFRPMC appears a better
impact resistance and energy absorbing ability than PC and SFRC. Based on the analysis of
experimental results, a rate-dependent damage model is suggested to depict the dynamic behaviors
of SFRC and SFRPMC, which derives the impact damage evolution of the materials. It shows that
the damages in SFRPMC develop more slowly than that in SFRC.
Effect of Thickness in Intermediate Layer on Intensity of Stress Singularity at a Vertex in Three-Dimensional Bonded Joints
Authors: Koguchi Hideo
Published: March 2009

In the present paper, singular stress fields at the vertex on the interface in three-dimensional
bonded joints are analyzed using BEM. The order of stress singularity is determined solving an eigen
equation based on FEM formulation and the stress distribution is expressed using the result of the
eigen-value analysis. A simple relationship between the thickness of layer and a value of stress is
introduced. Then, stress distributions for various thicknesses of layer are unified using the
relationship, and the unified intensity of stress singularity is determined.
Study on Constitutive Relation and Permeable Coefficient Tensor of Rocks under Tensile Stress Loading with Micromechanics
Authors: Wei Llide , Chen Cong Xin , Yang Chun He
Published: March 2009

In the present paper, a micromechanical based damage model and corresponding permeable coefficient tensor are developed for rocks under tensile stress and hydraulic pressure loading based on the concept of the domain of microcrack growth (DMG) . After choosing an appropriate fracture criterion for microcracks, we obtain the equations from which the DMG under a monotonically increasing proportional plane stress and an invariable hydraulic pressure loading is obtained. Then the overall effective stress-strain relations and the permeable coefficient tensor of damaged rocks are calculated. The theory is verified by test.
Research on Fracture Behavior of a Cracked Film-Substrate Medium
Authors: Liu Bao Liang , Bi Xian Shun
Published: March 2009

This study gives the problem of a crack in the film oriented perpendicular to the
film-substrate interface with the crack tip terminating at the interface. Based on Beuth’s theory,
three-dimensional model is simplified to plane strain problems, which obtains fracture mechanisms
of a cracked film-substrate medium by applying the boundary element method(BEM). The method
aptly resolves the problem involving stress concentration and, further, that this study develops the
multi-region boundary element method and applies it to evaluate the cracked film-substrate
medium. It shows that the stress intensity factor is affected by the different elastic mismatches and
the thickness ratio of the film and the substrate. These results indicate: 1) The stress intensity factor
has remarkable increased with the decrease of the thickness ratio of the film and the substrate. The
effect of the fracture behavior of film is negligible when the thickness ratio of the film and the
substrate is above 10, therefore, it is treated as thin film; 2) The stress intensity factor will decrease
with the increase of α ( −1 pα p +1) for β = 0 and β =α / 4 , where α and β are called
Dundurs parameters. What’s more, this paper studies the special condition of the film-substrate
medium, which is the analysis of the fracture of the absence of any elastic mismatch between the
film and the substrate, i.e.α=β=0, and revision of the formula of Xia and Hutchinson is put forward
for the stress intensity factor of the deep crack problems by comparing to the former conclusions of
Y.Murakami.