bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Spinel Growth on the Delamination of Thermal Barrier Coatings
Authors: Zhang Wei Xu , Sun Yong Le , Wang Tie Jun
Published: January 2011

The spinel growth induces undulation of the thermal growth oxide layer and decreases the service life of plasma-sprayed thermal barrier coatings. An analytical model is introduced to investigate the effect of spinel growth on the delamination of thermal barrier coating. The analytical results show that the number per unit area and the growth rate of spinel have significant influence on the delamination of thermal barrier coating. The stiffer and thicker thermal barrier coating is more easily to delaminate from the bond coat due to the existence of spinels. The effect of spinel on the delamination cannot be neglected. How to reduce the growth rate and the number of spinel is a key problem to prolong the service life of thermal barrier coatings.
Numerical Simulation of Dislocation-Precipitate Interactions Using Dislocation Dynamics Combined with Voxel-Based Finite Elements
Authors: Takahashi Akiyuki , Terada Yutaro
Published: January 2011

This paper provides a computational method for dislocation-precipitate interaction problems. The computational method is a combination of the parametric dislocation dynamics and the voxel-based finite element method, and has a potential to enable the simulation of interaction between dislocations and multiple precipitates. To reduce the computational time, a multi-level voxel element model is employed. The convergence behavior of numerical accuracy and the computational time of the proposed method are examined by solving a dislocation-precipitate interaction problem. The results show that the proposed method has a good convergence behavior, and the computational time can be drastically reduced by the use of the multi-level voxel element model. Finally, the interaction between dislocations and multiple precipitates is solved to demonstrate a potential of the proposed method with various average diameters and constant volume fraction of precipitate. As the result, the proposed method successfully captured the dependence of the critical resolved shear stress on the average precipitate diameter.
Prediction of the Mechanical Properties of Hot-Rolled Low Carbon Steel Strips in Correlation to Chemical Compositions and Rolling Conditions
Authors: Noppon Jiratthanakul , Chandra-ambhorn Somrerk
Published: January 2011

Seven thousand sets of data consisting of mechanical properties, chemical compositions, and rolling parameters of industrial hot-rolled coils were analysed using multiple regression. This was to establish empirical formulas to predict mechanical properties of steel as a function of chemical compositions and rolling parameters. The empirical formulas predicting yield strength (YS), ultimate tensile strength (UTS) and percentage of elongation (EL) of low carbon steel strip were obtained, e.g. YS = 461+ 418 C + 61.6 Mn + 796 P ¬– 303 S + 159 Si + 146 Cu + 204 Ni + 49.7 Cr + 1127 V + 1072 Ti + 3674 Nb – 266 Mo – 6299 B – 76.3 Al – 557 Sn – 3.54 THK – 0.00758 WID – 0.114 FT – 0.223 CT. The rolling parameters in equation included finishing temperature (FT), coiling temperature (CT), thickness (THK) and width (WID) of strip. R-Square values for the formulas predicting YS, UTS, and EL were 82.3%, 90.1%, and 75.8% respectively. These equations were validated by using another 120 hot-rolled coils. The averages of absolute values of the difference between the predicted and actual values of YS, UTS, and EL were 9.6 MPa, 7.8 MPa, and 2.7 % respectively. Correlation of chemical compositions and rolling conditions with mechanical properties was discussed in the paper.
Application of BEM for Improving Corrosion Assessment of Public Building Stricken by Tsunami Aceh 2004
Authors: Ridha M. , Fonna Syarizal , Huzni Syifaul , Fachrizal  , Ariffin Ahmad Kamal
Published: January 2011

The earthquake and tsunami that struck Aceh region on December 2004 caused many public buildings submerged by seawater. In long periods, it will promote the premature failure of the existing buildings constructed by reinforced concrete structure due to corrosion. Early detection of the corrosion is urgent. The corrosion assessment using haft-cell potential mapping has been conducted to understand the current status of public buildings after five years tsunami Aceh 2004. The results for four existing public buildings in the region show that the corrosion level of steel in concrete of the buildings was already at intermediate risk. However, these results show only the corrosion risk instead of the actual corrosion of the steel. To improve the corrosion assessment, BEM was employed by simulating some factors that might affect the measured potential on the concrete surface. Laplace equation is used to model the potential in concrete structure. The steel surfaces were represented by using polarization curves. BEM is employed to solve the Laplace equation; hence the potential and current density in the whole domain can be obtained. The simulation results show that the potential corrosion on concrete surface was significantly affected by corrosion of steel, concrete conductivity and concrete cover. Accordingly, by employing BEM, more precise corrosion of steel in concrete can be identified from the measured potential on the concrete surface. Moreover, further study is needed to apply the proposed method in the field.
An Approach for Landslide Stability Evaluation by Numerical Method
Authors: Liu Xiao Li , Yang Jun Jie
Published: January 2011

For numerical simulation, the shear strength reduction technique (SSRT) is often used to evaluate slope or landslide stability. According to numerical computation results of slopes or landslides analyzed by SSRT, it can be found that with increase of the shear strength reduction factor, some of the soil elements will yield gradually to form a connected plastic zone, which is the potential slip surface of the slope or landslide. In view of the plastic resistance of soils, formation of the connected plastic zone does not always indicate that the landslide is about to failure. Other auxiliary criterion is necessary to predict whether a slope or landslide is in a critical state or not. Here, difference of the incremental percent of horizontal displacement of the outcropping slip surface node is regarded as the auxiliary indicator to distinguish the critical state of slopes or landslides after formation of the potential slip surface. With the ideas mentioned above, stability of a fossil landslide, Xietan landslide has been analyzed for the natural and the long-term reservoir water level conditions. Factors of safety of Xietan landslide by the numerical method have been compared with that by the limit equilibrium method, which indicates that the method used here for evaluating stability of Xietan landslide is feasible. Because numerical method has more advantages over the limit equilibrium method, the approach for evaluating stability of landslide here can be applied to more complicated or three-dimensional landslides or slopes further.
Molecular Dynamics Simulation of Dislocation-γ-Precipitate Interactions in γ’-Precipitates
Authors: Takahashi Akiyuki , Terada Yutaro
Published: January 2011

There are clear experimental evidences of the formation of either spherical or platelet γ-precipitates inside cubic γ’-precipitates in nickel-based superalloys, which strengthen the mechanical property of the alloy. In this work, molecular statics (MS) and dynamics (MD) simulations of the interaction between a super edge dislocation and a γ-precipitate in γ’-precipitates were performed. The strengthening mechanism was then investigated by comparing the simulation results with the theoretical prediction. As the result, it could be found that the critical resolved shear stress (CRSS) of the interaction has a strong dependence on the shape of the γ-precipitate, and could be well predicted by the theory of precipitation strengthening. Especially, the stacking-fault, chemical, coherency and interface strengthening play a major role in determining the CRSS. Finally, the interaction under a finite temperature was simulated using the MD simulations. It was found that the influence of temperature on the interaction is negligibly small.
Failure Analysis of Steel Superheater Tube Fractured in a Boiler of a Power Plant
Authors: Huda Zainul
Published: January 2011

This paper presents a case study of ASME SA213 type-T22 alloy steel superheater tube that failed in a boiler of a power plant. The failed superheater tube was investigated by visual examination, metallography, optical microscopy, electron fractography, and hardness testing. Microscopic examinations revealed inclusion, pre-existing micro-cracks and cementite precipitates at the grain boundaries in the microstructure; which were thought to be one of the major causes of failure of the superheater tube. Another major cause failure of boiler type T-22 was found to be creep failure because the boiler had been under use for a long time (36573 hours) at high steam temperature of around 420 °C with 130 bar pressure. Finally, recommendations have been suggested to improve the material characteristics and properties of the superheater tube for application in boiler of the power plant.
A New S-N Curve Model of Fiber Reinforced Plastic Composite
Authors: Mu Peng Gang , Wan Xiao Peng , Zhao Mei Ying
Published: January 2011

Based on an amount of fatigue experimental data of fiber reinforced plastic composite, a new three-parameter S-N curve model is proposed to describe the relationships between the loads and fatigue life under constant amplitude cyclic loading. As the logistic curve behaves as sigmoidal which is the similar with previous S-N models, and from this comparability, an S-N equation with logistic’ form has been established. The model can assess the fatigue behaviors of FRP under various loading conditions, such as, tension-tension (T-T), tension-compression (T-C) or compression-compression (C-C) loading under different stress ratios of the whole region of fatigue life. Several examples are employed to illustrate that the model has ability to fit several different sets of experimental data accurately.
Observing Load Sequence Effects on Simulated and Experimental Fatigue Crack Growth Occurrence
Authors: Beden S.M. , Abdullah Shahrum , Ariffin Ahmad Kamal , Kadhim Nawar A.
Published: January 2011

Load cycle interactions can have a significant effect in fatigue crack growth (FCG) under variable amplitude loading. Studying of FCG and fatigue life calculation under spectrum loading is important for the reliable life prediction of engineering structures. Many models have been proposed, but yet no universal model exists. In this paper, a fatigue life predicted under various load spectra, using three different fatigue crack growth models namely, the Austen, modified Forman and NASGRO models. These models are validated with fatigue crack growth test data under various amplitude loadings. This application is performed with aids of three-point bend specimens of ASTM A533 steel material. The results clearly show the load sequences effect and the predicted results agree with some discrepancies between the different models as well as with the test data. Thus, neglecting the effect of cycle interaction in fatigue calculations under variable amplitude loading can lead to invalid life predictions.
Acceleration, Retardation and Crack Arrest in Stressed Heterogeneous Structures
Authors: Chekunaev Nikolay I. , Kaplan Anatoly M.
Published: January 2011

Hamiltonian of the solid body with a crack inside in field of tensile stresses was derived. Hamiltonian equations describe process of crack propagation. A crack propagation was considered in heterogeneous material when in ground matrix present inclusions with work-of-fracture per unit surface significantly greater than in the matrix. Condition of cracks arrest in such system was found and length of path, passed until crack’s stop, was calculated.
Stress Relaxation and Fatigue Characterisation of Eutectic SnPb Solder Alloy
Authors: Hashim Mohd Amin , Rahmat A.
Published: January 2011

Soldering is the most important joining technology in the semiconductor industry, especially for IC chip packaging. The binary eutectic SnPb alloy had been in used for decades, before regulations and restriction on the usage of lead in solders was imposed. Thus, replacing SnPb solder alloy with Pb-free solders has also been an issue in the electronic industry. The previously used SnPb alloy was in used due to several reasons, namely (a) it has low melting temperature (183oC) and solidified at a single temperature to form eutectoid composition, (b) binary in composition and is readily available commercially and (c) many researches had been undertaken in the previous decades. Creep, stress relaxation and fatigue tests were conducted on eutectic SnPb solder alloy in order to study the alloy mechanical characteristics, and hence a suitable Pb-free solder alloy could be chosen as a replacement alloy. In this study, creep, stress relaxation and fatigue tests were conducted on eutectic SnPb solder alloy at 30oC and 50oC, respectively. The study showed that stress relaxation in the alloy decayed instantaneously to zero-value when cycling was done at R=-1 and that cycling was done at 600 cycle per minute (CPM) which enable fatigue test to be conducted on the bulk solder alloy. A non-zero stress relaxation value will result in the alloy to failed predominantly due to creep and fatigue failure will not be observed.
Life Prediction of Rubber Automotive Components Using Finite Element Method
Authors: Samad M.S.A. , Ali Aidy , Arifin Mohd Khairol A.
Published: January 2011

The usage of rubbers has always been so important, especially in automotive industries. Rubbers have a hyper elastic behavior which is the ability to withstand very large strain without failure. The normal applications for rubbers are used for shock absorption, sound isolation and mounting. In this study, the predictions of fatigue life of an engine mount of rubber automotive components were presented. The finite element analysis was performed to predict the critical part and the strain output were incorporated into fatigue model for prediction. The predicted result shows agreement in term of failure location of rubber mount.
Investigation of Creep Fatigue Crack Propagation in Aluminium Tube
Authors: Mohammad K.A. , Ali Aidy , Oshkour A. , Barkawi Sahari B. , Abdullah Shahrum
Published: January 2011

Tubular structure is extensively used from domestic to aviation kind of applications. Life and safety are most considered in designing tube structure that against failure. For the last 200 years of research output and understanding, it was estimated that about 90% of metal failures were due to the external or surface defect and environmental attacks. The present work had focused on damage tolerant fatigue life prediction on aluminium cylindrical structures. Endurance tests were conducted with a constant amplitude repetitive loading at both, in room and high temperatures. A notch is introduced by wire cut machined on external surface and in a straight line with circumferential orientation to represent an external defects and flaws. Crack growth rates were measured by imaging technique. The experimental results suggested that the creep fatigue life is shorter than conventional fatigue life. The effect of stress ratio is also presented. The fully reversed with high temperature results registered the most severe damage with tremendous of life reduction.
Effect of Specimen Width on the Contact State between the Three-Point Bending Specimen and Supports in Hopkinson Bar
Authors: Guo Chun Huan , Liu Rui Tang
Published: January 2011

The effect of specimen width on the contact state between the three-point bending (TPB) specimen and supports has been investigated with the apparatus of Hopkinson pressure bar using the analysis method of the propagation of stress wave. The results indicate that, the time for loss of contact decreases linearly with the increase of specimen width when the specimen width is less than a critical value, and the relationship between the time for loss of contact and the specimen width shows a parallel line to the abscissa when the specimen width is greater than the critical value.
A Computational Study of the Overload Characteristic Curves of Projectile Penetrating Concrete
Authors: Deng Qiong , Li Yu Long , Yu Q.J. , Suo Tao , Xue P.
Published: January 2011

In the present paper, a concrete material is taken as a studying object, both the No. 16 and the JHC constitutive models in LS-DYNA commercial software are used because the parameters of both models are comparatively easy to obtain. The results show that, computational maximum value and the width of the overload curves are good agreement with experimental curves by using these two models in the Lagrange method. With increasing penetrating depth, the ramp and down slopes of the overload curves by computing is increasingly agreement with experimental curves. The JHC model is better to compute overload curves in the Lagrange method. The Lagrange method is also used to compute the penetration of multilayer concrete plate. It is found that, the peak value of acceleration goes down with increasing penetrating layers; this decreasing peak value depends on layer thickness and the strength. Acceleration value between layers will go to zero; this trend is agreement with experiments.
Influence of the Rise Time and Decay Time of Stress Wave on Spalling Process of Rock-Like Material
Authors: Chen Qing Yun , Zuo Yu Jun , Tang Chun An , Li Shu Cai
Published: January 2011

Using numerical code RFPA2D (dynamic version), spallation processes of rock-like medium induced by reflection of stress wave with different rise time and decay time are simulated, and based on description and discussion on the failure area in the document [1], the influence of the rise time and decay time of stress wave on spalling process of rock-like material are numerically analyzed and discussed. Results indicate that the comminution zone is affected little by the duration of stress wave regardless of the rise time or decay time, and the fracture zone is affected to a greater extent by the rise time than the decay time, and the spalling zone is affected to some extent by the duration of stress wave regardless of the rise time or decay time, also, the stability of specimen is affected by the duration of stress wave regardless of the rise time or decay time, and the specimen loses stability at a certain decay time earlier than that at the same rise time. Furthermore, the effects of rise time and decay time on the number of failure elements are also investigated. Results show that a shorter rise and decay time increase the number of radial cracks. At longer rise time and decay time, the number of cracks is reduced and the cracks extend longer. In addition, the spalling increases to some extent as the rise time or decay time decreases.
Prediction of Safety Factor for Slope Designed with Various Limit Equilibrium Methods
Authors: Mohamed Tariq , Kasa Anuar , Mohd Raihan Taha
Published: January 2011

The purpose of this study is to predict the stability of slope using adaptive neuro fuzzy inference system (ANFIS). Based on limit equilibrium theory, four different methods of analyses, i.e. Morgenstern-Price, Janbu, Bishop and Ordinary were used to calculate the overall safety factor of various slope designs. Neuro-fuzzy inference system was used to map from a given input to an output. Important parameters such as height of slope (H), unit weight of soil (γ), angle of slope (θ), coefficient of cohesion (c) and internal angle of friction (ф) were used as the input parameters while overall safety factor was the output. ANFIS model to predict the stability of the slopes was generated from the calculated data. Results showed that factors of safety predicted using ANFIS agreed well with factors of safety calculated using Limit Equilibrium Methods (LEM).
Mixed Mode Partition in one Dimensional Fractures
Authors: Wang Simon , Harvey Christ
Published: January 2011

Taking a double cantilever beam (DCB) as a representative of one dimensional fracture, a unique pair of pure fracture modes I and II are successfully found in the absence of axial forces, which are orthogonal to each other with respect to the coefficient matrix of the energy release rate. Although the pair are pure modes there still exist interactions between them. The interactions result in energy flow between the two modes and are successfully determined. With the presence of axial forces, there are two independent pure modes I and two independent pure modes II, which are orthogonal to each other as well. They are found and used to partition the total energy release rate.
Analytical Solution for Pin-Supported Metal Foam Core Sandwich Beam with Local Denting
Authors: Qin Qing Hua , Zhang Jian Xun , Wang Tao , Wang Tie Jun
Published: January 2011

Structural response of pin-supported metallic foam core sandwich beam is theoretically investigated. Effects of local denting and core strength and interaction of bending and axial stretching are considered in analysis. A rigid-plastic beam-on-foundation is employed to consider local denting deformation. The local denting continues during the overall deformation of sandwich beam. It is shown that upon neglecting the effect of local denting, the load-carrying capacity and energy absorption of sandwich beam may be overestimated, and the normal axial (membrane) force associated with plastic stretching substantially stiffens the sandwich beams.
Effects of Al2O3-13% TiO2 Coating Particle Size on Commercial Mild Steel via Plasma Spray Method
Authors: Hassanuddin Nik , Ghazali Mariyam Jameelah , Muchtar Andanastuti , Isa M.C. , Daud Abdul Razak
Published: January 2011

This paper discusses the effect of Al2O3-13% TiO2 agglomerated nanoparticle powders ranging from 20 to 60 m and microparticle powders ranging from 10 to 25 m on commercial marine grade mild steels using a plasma spray technique. Prior to coating, the nanoparticle powders were subjected to a 2 level factorial design of experiment to give a careful control and optimise the operational spray parameters as well as process by using the statistical methods. The method was focused on the primary gas pressure, carrier gas pressure and powder feed rate of the spray parameters. The optimum properties of wear rate, surface roughness and microhardness were identified by using the lowest primary and carrier gas pressure together with the highest powder feed rate. As for the microparticle powders, they were subjected to an optimum properties by using 35 kW plasma spray power. In this study, the plasma spray power for microparticle varied from 20 kW to 40 kW, while the other parameters such as primary gas pressure, carrier gas pressure, powder feed rate and spray distance were held constant. It was found that microparticle powders exhibited denser coating microstructure s and improved both surface roughness and microhardness. On the other hand, the nanoparticle powder coating gave a greater wear resistance than those of micro particle powders, which may likely due to the strengthening effect of both fully and partially melted region.
Effect of Static Pre-Strain on Low Cycle Fatigue Life of AISI 316L Stainless Steel
Authors: Ido Tomohiro , Komotori Jun
Published: January 2011

In order to clarify the effects of a great amount of static pre-strain (1/4 cycle) on fatigue life of AISI 316L stainless steel, strain controlled low cycle fatigue tests were carried out. Hardness and fracture ductility of specimens were measured. Results showed that in the case of a specimen with p=0.01, static pre-strain of 0.16 noticeably reduced a fatigue life. To clarify the reasons for the decrease in fatigue life with pre-strain, the maximum stress amplitude of the hysteresis loop was measured. In the case of the specimen with p=0.01, work softening was observed in the early stage of fatigue life. On the other hand, when the cyclic plastic strain ranges were p=0.10, no softening was observed. These results suggest that work softening is significant in determining the fatigue life of the specimens at a relatively low level of applied cyclic strain.
The Study on Fatigue Crack Propagation in Metal Using Finite Element Analysis
Authors: Zakaria K.A. , Abdullah Shahrum , Ghazali Mariyam Jameelah
Published: January 2011

Fatigue in materials is caused by repeated loading and unloading cycles below the ultimate strength of a material. Fatigue tests are expensive since they required a lot of time consuming. Simulation of fatigue crack propagation using commercial software can reduce the costs related to time. The purpose of this study is to compare the fatigue crack propagation in metal under variable and constant amplitude loading. A standard size of aluminum cast alloy specimen according to ASTM E647 document was modelled using a pre-processor and it was later being analysed. In another aspect, strain gauges were attached to an engine mounting bracket and connected to the data acquisition set in order to capture the actual strain signals when an automobile was driven on to different road conditions. For the simulation purpose, a constant amplitude loading was then derived from a variable amplitude loading obtained from the data capturing process. The related parameters on between different road conditions, variable and constant amplitude loadings and crack propagation rate were presented. The relationship between those parameters were finally correlated and discussed.
The Influence of Torsional-Rigidity Bounds for Composite Shafts with Specific Cross-Sections
Authors: Chan I Tung , Chen Tung Yang , Chiu Min Sen
Published: January 2011

We consider the Saint-Venant torsion problem of composite shafts. Two different kinds of imperfect interfaces are considered. One models a thin interphase of low shear modulus and the other models a thin interphase of high shear modulus. The imperfect interfaces are characterized by parameters given in terms of the thickness and shear modulus of the interphases. Using variational principles, we derive rigorous bounds for the torsional rigidity of composite shafts with cross-sections of arbitrary shapes. The analysis is based on the construction of admissible fields in the inclusions and in the matrix. We obtain the general expression for the bounds and demonstrate the results with some particular examples. Specifically, circular, elliptical and trianglar shafts are considered to exemplify the derived bounds. We incorporate the cross-section shape factor into the bounds and show how the position and size of the inclusion influence the bounds. Under specific conditions, the lower and upper bounds will coincide and agree with the exact torsional rigidity.
Effect of Plasma Spray Variables on Cu-Ni Coated A7075
Authors: Kamal S.E. Mat , Ghazali Mariyam Jameelah , Abdullah Shahrum
Published: January 2011

This paper discusses the effect of several variables in plasma spray method, namely; the flow rate, spray distance and power used on the mechanical properties of Cu-Ni coated A7075. All spraying techniques were designed using 23 factorial plans prior to the actual experiments. The produced coatings were characterised using a scanning electron microscopy (SEM). Morphological observation indicated that most sprayed particles were formed in splash shape splats. The effects of interactions between the response variable factors were screened using a response surface methodology. Three coating factors were used, namely, plasma power, number of coating layer and spraying distance where as the coating hardness and surface roughness were set as the responses. In general, an ideal parameter of 5 coating layers with a power of 30 kW and a spraying distance of 150 mm gave a maximum hardness of 622 Hv and a minimum surface roughness of 9.7 µm.
Failure of Composites with Discontinuous Fabric Preform under Bending
Authors: Do Thanh Trung , Lee Dong Joo
Published: January 2011

During the fabric preform and/or mold closure processes of the resin transfer molded composites (RTMCs), the discontinuous fabric patterns such as wrinkling and overlapping can be occurred and influenced the failure strength. It is found that the composites with discontinuous fabric preform had two failure mechanisms as functions of fabric ply number and discontinuous fabric length under the three-point bending. First, the failure modes can be related to the bend strengths that were controlled by the interfacial bonding strength depending on the discontinuous fabric length. Second, the failures were controlled by the potential strength of fabric when the discontinuous length reached the critical value. Moreover, the experimentally measured results of the normal and discontinuous preform models under bending were compared to examine the safety conditions as functions of fiber content and other factors.
Phase Field Simulation of Ferroelectrics with Cracks
Authors: Zhao Xiao Fang , Soh A.K.
Published: January 2011

By employing a dipole defect model, two-dimensional phase field simulations of domain switching in the crack tip vicinity of a crack embedded in a relaxor ferroelectric single crystal, which was subjected to mechanical loading and electric field, have been carried out. The interaction between the dipole defects and crack, the influence of the dipole defect concentration density on the switching process, and the coupling effect of mechanical stress and electric field on domain switching in the vicinity of the crack tip have been studied. Comparing the results obtained from relaxor ferroelectrics with those of normal ferroelectrics, the former showed that, due to the interaction between the dipole defects and crack, polarization switching in the vicinity of the crack tip was suppressed. Moreover, the coupling between applied mechanical stress and electric field can either promote or suppress domain switching in the vicinity of a crack.
Research of Surface Deformation with Metro Double Tunnels Construction and the Relative Position Change
Authors: Wu Yan Kai , Feng Wei
Published: January 2011

With the rapid development of our economy, the urban traffic becomes increasingly busy. To ease traffic congestion, underground rail transportation is becoming one of the main modes of transportation in city. At present in order to relieve the traffic congestion most major cities in China are accelerating the construction of subway tunnels. The relative position change of metro double tunnels and construction of the sequence will affect the surface subsidence deformation and the interaction of the tunnel lining. It is more concerned about these issues in tunnel design. It is the main purposes, in this paper, to analyze the metro double tunnels surface deformation, which affect by the position changes of new construction double and the sequence of construction. From the numerical simulating results, in order to reduce surface subsidence and ensure the structural safety over the subway tunnel, it should try to make double-tunnels at the same horizontal plane in design. If the double tunnels could not be located at the same horizontal plane, the double-hole tunnel construction sequence of the deformation of the surface subsidence effects are obvious it is obvious that the double tunnels construction sequence differently make the deformation of the surface subsidence. To reduce the deformation of the surface subsidence, it should be first excavated the shallow tunnels and then excavated the tunnel buried deeply. The ideal distance of the double tunnels center is greater than 4 times the tunnel diameter. It can make the surface subsidence reduce to the minimum during the metro tunnel construction.
Strength and Fracture Characteristics of SUS304/AL-Alloy Scarf Adhesive Joint with Various Adhesive Thicknesses
Authors: Afendi Mohd , Teramoto Tokuo , Matsuda Akihiro
Published: January 2011

In this study, strength and fracture toughness of epoxy adhesively bonded scarf joints of dissimilar adherends, namely SUS304 stainless steel and YH75 aluminium alloy are examined on several scarf angles and various bond thicknesses under uniaxial tensile loading. Scarf angles, θ = 45°, 60° and 75° are employed. The bond thickness, t between dissimilar metals is controlled to be ranged between 0.1 mm to 1.2 mm. Finite element (FE) analysis is also executed to investigate the stress distributions in the scarf joints by ANSYS 11 code. From analytical solutions, stress singularity exists most pronouncedly at the steel/adhesive interface corner of joints having 45° to 75° scarf angle. This is not only in agreement with the FE analyses results but also confirmed by fracture surfaces observation wherein the fracture has always been initiated at this point. The strength of scarf joints increases as the bond thickness decreases. Interface corner toughness, Hc approach can be applied when predicting the failure stress of scarf joints. Besides, for scarf joints with an interfacial crack, the fracture toughness, Jc values are independent of bond thickness and less sensitive to adherends. Moreover, Jc increases as mode mixity increases.
Simulation of a Bio-Adhesion System with Viscoelasticity
Authors: Tang M.M. , Soh Ai Kah
Published: January 2011

The present study focuses on investigation of the adhesive phenomenon of gecko with viscoelasticity using the finite element method. By simplifying a single spatulae as a flat-ended cylinder in contact with a rigid substrate, a model is devised to study the critical radius under which the stress becomes uniform for the adhesive structure. Furthermore, viscoelasticity is taken into consideration in the simulation model instead of elasticity. The critical cylinder radii determined are in agreement with theoretical calculations and experimental data.
Numerical Simulation of Rock Fracture under High Pressure Water Jet
Authors: Li Xiao Hong , Si Hu , Xie Yan Ming
Published: January 2011

The evolvement of rock fracture is a complicated and nonlinear dynamic problem. On the assumption that rock is homogeneous and isotropic, a numerical model was developed to simulate rock fracture under high pressure water jet based on continuum damage mechanics and nonlinear finite element method. The dynamic effect of rock was simulated by the dynamic contact method under high pressure water jet. The numerical simulation results showed that rock failure occurred within several milliseconds and the evolvement of it was for step under high pressure water jet and that the stress propagation in rock rapidly decayed with the distance from the jet centre. On the whole, the numerical results clearly exhibited the process of rock fracture and the extent of the water jet under high pressure water jet. It was important to the application of jet cutting rock theory and the development of water jet technology.
Fatigue Failure Behaviour Study of Automotive Lower Suspension Arm
Authors: Kadhim Nawar A. , Abdullah Shahrum , Ariffin Ahmad Kamal , Beden S.M.
Published: January 2011

Fatigue life of automotive lower suspension arm has been studied under variable amplitude loadings. In simulation, the geometry of a sedan car lower suspension arm has been used. To obtain the material monotonic properties, tensile test has been carried out and to specify the material mechanical properties of the used material, a fatigue test under constant amplitude loading has been carried out using the ASTM standard specimens. Then, the results used in the finite element software to predict fatigue life has been evaluated later to show the accuracy and efficiency of the numerical models which they are appreciated. The finite element analysis tool is therefore proved to be a good alternative prior to the further experimental process. The predicted fatigue life from the simulation showed that Smith-Watson-Topper model provides longer life than Morrow and Coffin-Manson models. This is due to the different consideration for each strain-life model during life calculations.
Investigation of the Correlation between IC Chip Pick-Up Performance and Peeling Behavior of Adhesive Tapes
Authors: Saiki Naoya , Inaba Kazuaki , Kishimoto Kikuo , Seno Hideo , Takahashi Kazuhiro
Published: January 2011

It was investigated that the influences of the peeling behavior of adhesive tapes in peeling tests on IC chip pick-up performance. Needles peel off an IC chip with an adhesive film from the base material in the pick-up process, by sticking out the backside of the base material. In the case that the peeling forces of the adhesive tape decrease as the peeling speeds increase in peeling tests, only two kinds of behaviors were observed in pick-up test; the peeling propagated little and the IC chip was not peeled off under critical needle displacement while the pick-up was completed instantaneously over critical needle displacement. In the case that the peeling forces of the adhesive tape increase as the peeling speeds increase, the pick-up time decreased as the needle displacement increased. As a result, it can be concluded that the needle displacement where the peeling propagates instantaneously is critical for succeeded pick-up if the peeling forces of the adhesive tape decrease as the peeling speeds increase. If the peeling forces of the adhesive tape increase as the peeling speeds increase, the information of peeling speeds at each needle displacement are needed to estimate how long it takes to pick-up a chip.
Experimental and Numerical Investigation of Rubber Extrusion Forming for Multi Material Automobile Weather Strip
Authors: Javadi Seyyed Mohammad , Alizadeh Elham , Rahimi Behnam , Hosseini Amir
Published: January 2011

Rubber extrusion process is the most complex and important problem in the production of automobile weather strips. To achieve a specified geometry for an extrudate profile, together with a minimum degree of pressure loss, flow balancing of die is required. To attain this objective, the flow characteristics in die channel must be accurately described, and this demands a computational code able to predict complex 3D flow patterns. In this paper, experimental data and tree-dimensional finite volume simulations of the melted rubber flow in die region, during extrusion forming process are presented. For melted rubber flow modeling, the conservation equations of mass, momentum, and energy are solved using a 3D computational code based on the finite volume method. The shear viscosity of the melted rubber flow is described by the power-law and Arrhenius-law models, and the governing equations parameters are interpolated by the least-square fitting of experimental values that gained by Rubber Process Analyzer (RPA). The flow in one of two dies, called plate die, is found to be highly unbalanced. In the second die, by using a feeder plate, the flow at the exit of the die was properly balanced. Experimental results show that for a die with balanced flow rate, extruded profile closely matches the designed profile. Also, reveal that in low-velocity regions of die exit, the profile section tend to contraction.
Free Vibration of Tire Road Contact
Authors: Sabri M. , Ariffin Ahmad Kamal , Nor Mohd Jailani Mohd
Published: January 2011

In this paper, a simulation procedure for tread patch to the road under consideration of contact effects is introduced. In particular, the treadband has been treated as an infinite tensioned beam resting on an elastic foundation. A contact model specially suited for the contact pairing rubber and rough road is developed. The main objective is here to predict the vibration generated from a system mentioned above by locating harmonic point forces representing the exitation of treadband at the contact patch. The simulations are carried out by means of the Finite Element Method in a structure vibration of tire. Exemplary simulation results are presented for 3D models of tire tread block and road. This model can be used as a tire design guide for selecting parameters which produce the minimum noise radiation.
Solid-Liquid Flows Simulation for Debris Avalanche Analysis
Authors: Toyoshi Takuya , Wada Yoshitaka , Kikuchi Masanori
Published: January 2011

From a view point of engineering application, solid-liquid flow is one of the most practical phenomena, however MPS and other particle methods usually premises a constant size of all particles in the model.　In a realistic phenomenon, the size of those particles is different.　 Koshizuka et al. has proposed new algorithm for solid-liquid flow simulation which is multi-scale DEM-MPS method. The method can calculate solid -liquid flow with a large difference of the particle scale. However, its program code requires a DEM part and a MPS part, and actual phenomenon includes various scales of particles. In order to analyze solid-liquid flow with different particles, modified Laplacian model and variable cut-off radius MPS method is proposed. This modification can directly deals with small particles and large particles. Calculation cost is kept and visualization of the results has more reality by these modifications.
Research on Pre-Loaded Composite Irradiated by Laser Beam
Authors: Long Lian Chun , Chen Zhong Ying , Yang Zhi Guang
Published: January 2011

This paper investigates failure behavior tests of T300/AG80 composite laminated specimens under tensile and compressive preload using a load holding device and laser irradiation from an Nd: YAG laser. By changing the magnitudes of the preload and the power densities of the laser, the effects of preload and laser power density on the time-to-failure of the specimens were observed. The response process of specimens was synchronized taken in using high-speed camera in experiment. The experimental results showed that tensile mechanical properties of T300/AG80 composite laminated specimens were obviously superior to ones in compression test. The relational expressions between the time-to-failure of specimens and pre-loads as well as with laser power densities were acquired through fitting experiment data. The time-to-failure reduced with the pre-load increasing, the relationship is approximating linear when the laser power density kept invariable. When the pre-load kept unchanged, the time-to-failure reduced as the laser power density increased. The relationship is approximating exponential. A basis for life prediction of structure mechanically loaded in either tension or compression during the irradiation by laser is provided by fitting expression.
Sensitive Analyses of Probabilistic Fracture Mechanics for Reactor Pressure Vessel during Pressurized Thermal Shock and Comparison with the Results of International Round Robin Analyses in Asian Countries
Authors: Kanto Yasuhiro , Yoshimura S.
Published: January 2011

This paper demonstrates sensitive analyses of probabilistic fracture mechanics (PFM) for reactor pressure vessel (RPV) during pressurized thermal shock (PTS) loading, and comparison of our calculation with the results of the international round robin (RR) analyses in Asian countries (Korea, Taiwan and Japan). The international Round Robin activity was performed in PFM sub-committees in the Atomic Energy Research Committee of Japan Welding Engineering Society (JWES) in conjunction with Korea and Taiwan research groups. The purposes of this program are to establish reliable procedures to evaluate fracture probability of reactor pressure vessels during pressurized thermal shock and to maintain the continuous cooperation among Asian institutes in the probabilistic approach to nuclear safety. Some parameters to RPV failure probabilities are chosen to evaluate their significance quantatively. The differences caused by selection of analyzing programs and some input parameters will be discussed.
Buckling Analysis and Optimization of Stiffened Cylindrical Shells under Uniform Axial Compression
Authors: Chen Xing Hua , Long Lian Chun
Published: January 2011

Thin cylindrical shells are widely used in modern structures. When the structures are under axial compression, inflectional destruction happens early. In order to design reasonable and reliable shell structures, stiffened cylindrical shells are applied in the dissertation, ANSYS, an valid finite element analysis software, is employed to redevelop and set up parameter calculation model, subjected to volume and variables value range restriction, the structure’s critical buckling load is the objective, and the serial linear programming optimization procedure is executed as well as the optimized thickness of shell and the size of stiffeners are gained accordingly. The critical buckling load of the structure is obviously increased after optimization, and the feasibility of this method is validated due to the comparison with the numerical and theoretical result.
Characterization of Shot Peened 2024-T351 Aluminum Alloy
Authors: Zaroog Omar Suliman , Ali Aidy , Barkawi Sahari B.
Published: January 2011

Specimens of 2024-T351 aluminium alloy under different three shot peening intensities were studied. The modifications of the surface layers of the shot peened specimens were investigated through microhardness, surface microstructure and residual stress relaxation after the first and second load cycles under two cyclic loads. No significant changes in microstructure after the three shot peeing intensities were observed with respect to untreated specimens. Rapid residual stress relaxation was observed in specimens after the first cycle. Relaxation of residual stresses occurred within first loading cycles were increased with increasing loading stress amplitude and due to quasi-static relaxation effects.
Study of Abrasive Wear Mechanism through Nano Machining
Authors: Islam Sumaiya , Ibrahim Raafat N. , Das Raj
Published: January 2011

The objective of this paper is to understand the abrasive wear mechanism for producing a nano scale groove on a bulk material through nano machining. A nano indenter equipped with a nano scratching attachment was used for nano machining operation and in situ observation of the machined surfaces. Two different tools (Berkovich and Conical) with the same tip radius (100nm) but different edge geometries were used to machine both Copper and Nickel coatings. It was found that the percentage of elastic recovery was lower for Cu than Ni during this nano machining operations. Hence, the deformation mechanism in nano machining operation was identified as elasto-plastic in nature as opposed to the well established completely plastic mode of conventional machining operations. The pile up volume due to plastic deformation was utilized to distinguish between the ploughing and cutting modes of abrasive wear mechanisms. The results reveal that the ploughing mechanism was dominant for Cu and the cutting mechanism was dominant for Ni machining. Moreover, both mechanisms ploughing and cutting were the dominant modes of abrasive wear using the Berkovich tip compared to the Conical tip for producing a nano scale groove through nano machining.
Study on Complex Structure Mesh Generating of Hexahedron Element Based on Improved Waveform Mesh Generating Method
Authors: Wang Xu Fei , Gheni Mamtimin , Kikuchi Masanori , Liu Ju Rong
Published: January 2011

Three-dimensional finite element method (FEM) is widely used as an effective numerical simulation technique to solve the complex engineering problem. Usually, the more complex engineering problem has more complex structure and shape; the FEM simulation technique is that needs to discrete the structure and shape of the problem by mesh. In addition, the correct generation of mesh is one of the most significant issues that directly affect to the accuracy of the FEM simulation. The hexahedral mesh is better than tetrahedral mesh in solving the complex engineering problem. The common methods of hexahedral automatic mesh generation have been used in some commercial soft already, but its adaptation is not enough to solve for practical applications of the complex engineering problems. A new method of mesh generation technique was proposed by improved waveform mesh generating method, and realized by C++ developing program in Linux OS. The method could generate some effective and smoothly mesh models by quadrilateral element or hexahedron element, and not only generated revolution curve surface meshes, but also generated random meshes according to free functions too. The results shown that the hexahedral mesh models of the complex shapes were generated as the shape function apply to regular mesh side as a waveform constraint.