bluuebunny/crossref_metadata_2025 huggingface dataset:
On the Crack Propagation Trajectory of Central Cracked Plates under Mixed Mode Loading Conditions
Authors: Souiyah Miloud , Muchtar Andanastuti , Ariffin Ahmad Kamal
Published: January 2011

A Finite Element (FE) programme for crack propagation was developed by using a source code written in the FORTRAN language to evaluate the Stress Intensity Factors (SIFs) and to predict the crack propagation trajectory. In this study, a Central Cracked Plate (CCP) with two holes under mixed mode (I & II) loading conditions is considered. Finite Element Analysis (FEA) combined with the concepts of Linear Elastic Fracture Mechanics (LEFM) provides a practical and convenient means to study the fracture and crack growth of the solid materials. The Displacement Extrapolation Technique (DET) is performed on this work in order to compute the stress intensity factors (SIFs) during the crack propagation. Additionally, to validate the capability and the reliability of this developed FE programme, the results of the current study are compared with experimental results from the literature.
Effect of Notched Parameters on Stress Field of Shaft under Torsional Loading
Authors: Li You Tang , Ma Ping , Yan Chang Feng
Published: January 2011

A model of notched shaft in which the crack, V-notch, U-notch and arc were described as notch uniformly, was put forward. The stress field near the notch tip of notched shaft was given using quadric coordinate system by selecting an appropriate displacement function at first, and then the stress field in Cartesian co-ordinates system was obtained. The 3-D model was set up and the local stress and strain near the tip of notch was calculated by using finite element software ANSYS, and the effect of notched parameters of shaft on stress was analysed. The results show that there is a small region, in which the effect of the tip radius and depth on the stresses is obviously. The effect of an open angle of notch on stress is very small. The smaller the ratios between the tip radius and depth of notch, the larger the stress concentrations near the tip of notch.
Fatigue Strength Degradation by Irreversible Hydrogen in Cold Drawn Eutectoid Steels
Authors: Nakatani Masanori , Minoshima Kohji
Published: January 2011

The fatigue tests were conducted for cold-drawn eutectoid steels having different activation energies and microstructures to investigate the mechanism of fatigue strength degradation by irreversible hydrogen. The fatigue strength of a sample with low activation energy was decreased by irreversible hydrogen, whereas the fatigue strength of a sample with high activation energy was not. When the activation energy for irreversible hydrogen becomes small, the desorption of irreversible hydrogen from its trap site is easily induced by cyclic loading, which results in a decrease in fatigue strength. When a sample having high activation energy was annealed at 473 K, the fatigue strength was decreased by irreversible hydrogen although the activation energy barely changed. This is because the precipitation of fine carbides due to annealing causes higher sensitivity to hydrogen embrittlement. High sensitivity to hydrogen embrittlement was concluded to induce the fatigue strength degradation by irreversible hydrogen. Therefore, the degradation of fatigue strength by irreversible hydrogen depends on the activation energy and sensitivity to hydrogen embrittlement.
Mechanical Properties of Carbon Fiber Reinforced Plastics under Hot-Wet Environment
Authors: Katogi Hideaki , Takemura Kenichi , Shimamura Yoshinobu
Published: January 2011

Water absorption behavior and flexural strength properties of carbon fiber reinforced plastics (CFRP) under hot-wet environment were examined. Those of epoxy resin were also examined for reference. Weight gains of CFRP and epoxy resin were measured after immersion in distilled water at temperatures under 90°C. Quasi-static flexural tests of CFRP and epoxy resin were conducted after immersion for 180 days. Weight gains of CFRP and epoxy resin increased with increasing water temperature. After immersion for 180 days at 90°C, weight gain of CFRP became 3.3times higher and that of epoxy resin was 2.3 times higher than that at RT, respectively. When CFRP and epoxy resin were immersed in distilled water at 90°C, weight gains of CFRP and epoxy resin increased and then decreased. Flexural strengths of CFRP and epoxy resin decreased in distilled water at temperatures less than 90°C. Flexural strengths of dried CFRP and epoxy resin after immersion recovered but were lower than that of virgin CFRP and epoxy resin. Debonding of fiber/resin interface and crack initiation in epoxy resin in distilled water resulted in the strength reduction.
Comparison on Compressive Behaviour of Aluminium Honeycomb and Titanium Alloy Micro Lattice Blocks
Authors: Hasan Rafidah , Mines Robert A.W. , Shen Eva , Tsopanos Sozohn , Cantwell Wesley
Published: January 2011

The paper discusses the compressive behaviour of two materials, the conventional aluminium honeycomb and the new titanium alloy micro lattice blocks. The new titanium alloy micro lattice structure is being developed as core material candidate in sandwich construction for aerospace application. Experimental tests have been done on the blocks in order to compare its property with the aluminium honeycomb. Compression strength as well as compressive behaviour of both materials are compared and observed. The mechanisms that contributed to the differences in their performance are discussed and this will be used to improve the geometrical and structural design of micro lattice structure in order to achieve properties that are superior or at least comparable with that of aluminium honeycomb.
Pre and Post Processing for Boundary Element Method (BEM) 3D Reinforced Concrete Corrosion Simulation
Authors: Fonna Syarizal , Ridha M. , Huzni S. , Ariffin Ahmad Kamal , Israr
Published: January 2011

Corrosion simulation of rebar in concrete structures using BEM 3D have been developed. However, pre processing procedure such as geometry development and meshing is still performed manually. In addition, the visualization of BEM simulation results is still illustrated using the simple chart and graph. Nowadays, many softwares have been developed under open source platform that can be used freely. There is open source softwares for CAE purposes such as Salome and VisIt. The aim of this study is to implement the open source software as pre- and post-processing for the developed BEM 3D code in order to simulate corrosion of reinforced concrete. Salome 2.3.9 is used for developing geometry and meshing the model. The visualization of the simulation results are conducted using VisIt 1.8. The study shows that the open source software i.e. Salome and VisIt, perform well as pre and post processing of developed code for simulating the corrosion of reinforced concrete. It shows that the meshing procedure and the interpretation of results become simpler and easier.
Inelastic Seismic Response of RC Building with Control System
Authors: Hejazi Farzad , Kojouri Samira Jilani , Noorzaei Jamal , Jaafar M.S. , Thanoon W.A. , Abdullah A.Ali Abang
Published: January 2011

Conventional buildings are mainly designed based on elastic analysis of structures subjected to moderate earthquakes. In this case, the seismic forces are much smaller than the forces introduced by strong ground motions with the considered structural behavior going to nonlinear response during these severe earthquakes. Improving the earthquake resistance of reinforced concrete buildings using a variety of earthquake energy dissipation systems has received considerable attention in recent years by civil engineers. In the present study, a nonlinear computational scheme was developed to predict the complete nonlinear dynamic response of reinforced concrete framed buildings equipped with viscous damper device subjected to earthquake excitation. A finite element program code is developed based on the nonlinear analysis procedure of reinforced concrete buildings equipped with viscous damper devices and a two dimensional, five story models of RC buildings subjected to earthquake were analyzed. Result of nonlinear analysis of RC buildings which furnished by viscous dampers indicated that using of viscous dampers effectively reduced the damages occurring in the building and structural motion during severe earthquakes.
Effect of Interfacial Reaction in Sn-Ag-Cu Solder Alloy with Ni Addition
Authors: Watanabe Hirohiko , Shimoda Masayoshi , Hidaka Noboru , Shohji Ikuo
Published: January 2011

Sn-Ag-Cu-Ni-Ge solder alloy has been developed to improve the mechanical properties of the Sn-Ag-Cu base solders and prevent oxidation of those solders. In this paper, an interfacial reaction and microstructure between the solder and a Cu electrode were investigated under heat exposure conditions. It was found that intermetallic compounds growth at the interface of the solder and the Cu electrode was greatly affected by amounts of added elements. Adding Ni in the solder can suppress the formation and growth of intermetallic compounds (IMCs) such as Cu-Sn and decreasing the amount of adding Ag in the solder can prevent the formation and growth of Ag3Sn. Moreover, it was found that there was an effect of suppress the growth of the Cu3Sn formed on the interface of Cu and (Cu,Ni)6Sn5 by adding Ni from analysis results of EDX and TEM.
Fracture Analyses for Interface Corners in Elastic Materials Subjected to Thermal Loading
Authors: Hwu Chyan Bin , Kuo Tai Liang , Huang Chun Chih
Published: January 2011

By employing the Stroh formalism for two-dimensional anisotropic thermoelasticity, fracture analyses of interface corners between two dissimilar anisotropic elastic materials under thermal loadings are considered in this paper. It was proved that the consideration of thermal effects will not influence the stress singularity but will induce heat flux singularity if the singularity of the temperature field is not permissible. To calculate the stress intensity factors via path independent H-integral, it was found that the one proposed previously for the mechanical loading conditions should be modified by adding an additional surface integral accounting for the thermal effects. Two examples considering cracks and corners in isotropic plates are presented to show the correctness and validity of the modified H-integral.
Experimental Investigation of Residual Thermal Stress in Thermal Barrier Coating (TBC)
Authors: Song Yan , Fang Qin Zhi , Wang Tie Jun
Published: January 2011

Residual thermal stress, which has a strong effect on the coating performance, is generated during the fabrication of TBC. In this paper, the residual thermal stress in TBC (92%ZrO2-8%Y2O3) with two different thicknesses (0.38 mm and 0.90 mm) is analyzed with a bi-material model. TBC specimens were sprayed by an Air Plasma Spray (APS). In addition, a chemical material removal method was used to obtain TBC specimens after it cooling down to the room temperature. Before and after the coating removed from the substrate, the deformation of the TBC was measured. Then the bi-material model was used to calculate the residual thermal stress in the TBC. The experiment result shows that, the residual thermal stress in thin TBC is smaller than that in thick TBC (the average residual thermal stress in thin and thick specimens are 145.5 MPa and 225.13 MPa respectively). The micro-structures in thin and thick TBC are also observed and discussed.
The Effect of Aging and the Protective Coating on the Oxidation Behavior of 6061Al/SiC Composite at High Temperatures
Authors: Rajasekaran S. , Udayashankar N.K. , Nayak Jagannath
Published: January 2011

This paper analyses the effect of ageing on the oxidation behavior of 6061Al/SiC composite material at temperatures ranging from 500 to 800 K. Also aluminum coating is employed as protective coating in order to improve the oxidation resistance of the composite. SEM, EDAX, XRD and stepped oxidation measurement techniques are used to study the oxidation behavior and to characterize the composite specimens. Oxidation of the composite material without protective coatings is seen to be very rapid during the initial stages of exposure to the high temperatures but subsequently slowed down due to the formation of a protective surface layer of oxide. Among the artificially aged composites, peak aged specimens are more prone to oxidation. The oxidation was especially severe above 600 K. The interface between the matrix and reinforcement particles and the grain boundary regions of the matrix enhance this oxidation process since they provided sites for oxidation initiation. Aluminum coating on the composite obtained by DC magnetron sputtering technique, reduce the oxidation rate effectively since the interface regions between the matrix and reinforcement, grain boundary regions of the matrix are unexposed to the atmosphere. Aluminum coating provides better oxidation resistance for the artificially aged composites.
Numerical Analysis of Elastoplastic Behavior of Foams with Ellipsoidal Pores
Authors: Xu Zhi Min , Zhang Wei Xu , Wang Tie Jun
Published: January 2011

The objective of this work is to numerically investigate the elastoplastic behavior of closed-cell foams. Anisotropic geometry with ellipsoidal pores is considered and the contribution of the inner gas pressure within the cells is incorporated to the model. Based on face centered cubic (FCC) arrangements of pores and the finite element method, macroscopic elastic constants and initial yield stress against the relative density and cell aspect ratio are discussed in this paper. Through a systematic study we find that the initial yield stress is dependent on the loading direction. The inner gas pressure results in the asymmetry of uniaxial tensile-compressive stress-strain curves and significantly affects the initial yield stress of the foams for different loading directions.
Effect of Aluminum Nitride (AlN) Addition on Wear and Mechanical Properties of Al-Si Alloy Composites Fabricated by Stir Casting Process
Authors: Wahab Mahamad Noor , Ghazali Mariyam Jameelah , Daud Abdul Razak
Published: January 2011

The effect of AlN addition in Al-Si alloy composites on the mechanical properties and dry wear behaviour were studied using pre-selected parameter conditions. In this work, high purity of AlN powders with different weight percentage of 5, 7 and 10 were used as reinforced materials for the composites. Morphology of the reinforced composite indicated that both silicon grains and inter-metallic compounds were surrounded by the AlN particles. The presence of AlN in the Al-Si alloy showed a significant improvement in tensile properties in which 7wt% of AlN addition increased up to 25% compared to those of without any reinforcements. Fracture morphologies with small dimples, tear ridges and necking features indicated that ductile fractures had occurred on the Al-Si composites. At 25N load, alloys with 5wt% of AlN exhibited high wear resistances whereas at 70N, alloys with 10wt% of AlN showed a great improvement in wear resistance. SEM investigation also revealed that the presence of wear was also marked with prominent grooves, craters and scoring marks. Overall, alloys with 7wt% AlN addition possessed great improvement in hardness, tensile and wear resistance properties.
The Resistance of Metallic Sandwich Plates to Blast Loading
Authors: Zhang Jian Xun , Qin Qing Hua , Wang Tie Jun
Published: January 2011

The resistance of metallic sandwich plates to blast loading is studied in this work. Two typical cores, i.e. trapezoidal plate core and metallic foam core are considered in the analysis. The normal and longitudinal compressive stresses of the trapezoidal plate core are analytically and numerically obtained. Large deflection and resistance of metallic sandwich plates to blast loading are numerically analyzed. The results are compared with that of monolithic solid plates made of the same material and having equivalent weight. It is shown that the well-designed sandwich plates possess higher resistance to blast loading than monolithic solid plates.
Failure Analysis of a Herringbone Gear
Authors: Netpu Samroeng , Srichandr Panya
Published: January 2011

Herringbone gears are extensively used in numerous engineering applications including gearboxes. Premature failures of such gears could lead to many serious consequences such as process downtime and late delivery which are critically important in this day and age of intense competition. This paper reports the results of failure investigation of a herringbone gear in a reduction gearbox used in a hot rolling steel re-bar mill in Thailand. The gear fractured after only 24 hours of service. The fractured gear was inspected visually and macroscopically, and all critical dimensions were measured. Chemical compositions of the materials were analysed. Fracture surfaces and microstructure of gear material were examined, and microhardness measured. Stress analysis was performed using finite element methodology. It was found that the premature failure of the gear, which appeared as a longitudinal crack, was due to excessive stress. The crack originated at the root of the keyway. Careful examination revealed that there was a slight misalignment between the key and the keyway which resulted in excessive stress. The lesson learned from this failure is that manufacturing defects, however slight, could lead to premature failures of key components such as gears, and could be very costly. It is recommended that apart from proper designs of components, good manufacturing practices are also necessary to minimize the chance of premature failures.
Development of Tensile Test to Investigate Mechanical Adhesion of Thermal Oxide Scales on Hot-Rolled Steel Strips Produced Using Different Finishing Temperatures
Authors: Ngamkham Komsan , Niltawach Satian , Chandra-ambhorn Somrerk
Published: January 2011

The objective of this work was to carry out tensile tests to investigate the effect of finishing temperature on mechanical adhesion of thermal oxide scale on hot-rolled low carbon steel strips. Two hot-rolled low carbon steel strips were produced in an industrial hot rolling line by fixing a coiling temperature at 620 °C and varying finishing temperatures at 820 and 910 °C. Two testing methods were conducted. First, each of a number of samples was subjected to a given imposed strain with ex-situ imaging of scale surface after straining. Second, only one sample was strained in a test with ex-situ imaging of scale surface at every 2 mm elongation of the sample. A spallation ratio, an area where scale was spalled out and normalised by the total area observed by microscope, was plotted as a function of the imposed strain. These two methods gave the same tendency of results as follows. At a given strain, the spallation ratio of scale on steel produced using higher finishing temperature was larger. The gradient of spallation ratio with respect to the imposed strain of that scale was also steeper. This reflects the higher susceptibility of scale to spall out with increasing imposed strain. This behaviour might be related to the larger thickness of scale on steel produced using higher finishing temperature. For the second testing method, lowering the magnification of microscope to observe scale spallation from 50x to 20x increased R2 of the curve of spallation ratio versus the imposed strain, as well as improved the reproducibility of the test.
Ductile Fracture Simulation of Pipe under Bending with Initial Defects
Authors: Kikuchi Masanori , Senda Ryotaro
Published: January 2011

Crack propagating evaluation is needed to predict and prevent structural damages since many structure defects from numerous crack propagating. It is widely known that ductile fracture occurs when external load is exerted to the material, these load include strong and unpredictable load such as earthquakes and collision of objects. Ductile material fractures via nucleation of void, growth of void and coalescence of voids. Many studies have been conducted; Kikuchi and Sannoumaru have published papers on the studies of ductile fracture. In the first paper [1], the thickness effect on the microscopic fracture process and fracture toughness is studied experimentally. In the second paper [2], dimple fracture tests were performed using three point bending specimens. In the test, loading condition is changed from mode I to mixed mode condition to study the effect of the mixed mode loading. Numerical simulation is conducted using Gurson’s constitutive equation. It is found that crack growth direction is affected significantly by the loading condition. Ductile fracture of a pipe used in Light Water Reactor components is researched in this paper. Four point bending of a pipe experiment had been done by the Central Research Institute of Electric Power Industry [3]. They were experimented in two conditions; one at room temperature (23 ) and second at high temperature (300 ). As a result, crack propagation behavior differs largely form each other. At room temperature, crack propagates parallel from the pre crack, and at high temperature, crack propagates in a slanting direction from the pre crack. Results show that that difference from the two temperature distinction of a tensile test in a stress strain curve is very little. In this paper, this problem is studied at first by experiments, observation of fracture surface and numerical simulation.
Influence and Sensitivity of Inertial Effect on Void Growth Behavior in Ductile Metals
Authors: Liu Bin , Li Zhen , Xu Fei , Kikuchi Masanori
Published: January 2011

This paper presents the dynamic growth behavior of the voids in ductile metals under dynamic loading condition. Started from energy conservation law, a dynamic damage model on void growth process is developed, in which inertial effect is taken into account. The proposed model on void growth is introduced into Gurson model through VUMAT subroutine, so the void growth behavior affected by inertial effect can be investigated and compared. Numerical analysis shows that inertial effect decreases the rate of void growth, and with the increasing of the loading rate, the decreasing effect becomes more remarkable. Inertial effect is very sensitive to the initial damage of the material and the distribution of the void density. The larger the initial damage and the sparser the void density, the stronger the inertial effect on the void growth.
A New Static Nonlinear Procedure for Assessment of Seismic Performance of High-Rise Buildings
Authors: Zhang Q.W. , Megawati K. , Huang L.P. , Pan T.C.
Published: January 2011

A new static nonlinear pushover procedure is proposed for assessment of seismic capacity for high-rise buildings. Rather than simply combining the results carried out by modal inertia force distributions to estimate the total building capacity after pushover analysis, the present study develops in advance the most critical lateral load distribution which is developed via energy dissipation analysis based on least-energy principle. The advantage of the present method is that the effect of different earthquake input directions can be well considered, as well as that unstable solutions due to employing linear method to combine the nonlinear analysis results can be avoided. Thus, the performance of building can be evaluated more reasonably. By comparing with the results from nonlinear response history analysis using real earthquake tremor monitoring results, the validity of the present method is validated.
The Stress and Strain Concentrations Associated with Two Interacting Holes in a Finite Thickness Elastic Plate Subjected to Tensile Stress
Authors: Yang Zheng , Hou Jian , Wang Guo Yin , Xiong Zhi Hua
Published: January 2011

The elastic stress and strain fields of a finite-thickness plate containing two interacting holes are systematically investigated using the finite element method. The maximum stress and strain concentrations occur on the mid plane only in the thin plates. They do not occur on the mid plane and their locations are different in the same plate for the thick plates. The values of the maximum stress and the strain concentration factor and their locations depend on the distance between the two holes and the plate thickness. The stress and the strain concentration factor are different, even if in an elastic state. The stress concentration factor and the strain concentration factor on the plate surface decrease rapidly with increasing thickness and becomes lower than the values corresponding to the plane stress state and the values of the mid plane. They are too low to reflect the overall stress concentrations as the plate thickness increases. The differences between the maximum value and the surface value of the stress concentration factor, the strain concentration factor increase rapidly and tend to their respective constant values with increasing plate thickness. These constant values depend on the distance between the two holes and the difference of the stress concentration factor is larger than that of the strain concentration factor in the same plate.
Steady-State Crack Propagation in Stressed Elastic Solid
Authors: Chekunaev Nikolay I.
Published: January 2011

A crack, symmetrically propagating in elastic material, was considered as superposition of surface Rayleigh waves. The self-similar growth of face loaded crack was considered in detail. Exact expressions of deformation and stress fields in the crack’s surrounding were found and asymptotic behavior of stress near cracks’ tips was also obtained. A condition that determines the crack’s velocity of self-similar propagation was found.
Simulation and Experimental Analysis of Fatigue Crack Growth under Cyclic Loading
Authors: Beden S.M. , Abdullah Shahrum , Ariffin Ahmad Kamal , Al-Asady N.A.
Published: January 2011

The problem of crack growth is a major issue in the prediction and maintenance of engineering structural elements. Prediction of expected life of a structural element due to constant (static) and alternating loading (fatigue) is of major concern to the designers. Prediction of remaining life of the structural elements influences the decisions of maintenance engineers (checking intervals, corrections, and replacements).The fatigue crack growth rate, which determine the fatigue life of the components after crack initiation need to be experimentally and theoretically investigated. In this study, fatigue crack growth tests were conducted under constant amplitude loading at a stress ratio of 0.1, using three-point bend (TPB) specimens of ASTM A533 steel material. For the simulation part of this study, three fatigue crack growth models, i.e. the Paris, modified Forman and Austen were examined. None of the models has a fit for the fatigue crack growth rate data in a similar behaviour compared to others. The modified Forman model provided a closer fit than the Paris model with respect to the experimental results. However, the Austen model provided the best fit to the fatigue crack growth rate data as compared with the other two models. Therefore, this model is suggested for use in critical applications.
Effect of Crack on Interfacial Stresses of RC Beam Strengthened with CFRP
Authors: Guo Yong Chang , Huang Han Lin , Li Li Juan , Deng Jun , Zhong Gen Quan
Published: January 2011

External bonding of fiber reinforced polymer (FRP) plates or sheets, because of their advantages, such as high strength to weight ratio and good resistance to corrosion, has become a popular technique for the strengthening and upgrading of structurally inadequate or damaged reinforced concrete (RC) structures. Interface debonding failure is one of the most common failure modes of the FRP strengthened RC structures. In this paper, the damaged concrete constitutive model is established and the effects of crack on the interfacial stresses of RC beam strengthened with CFRP are investigated. Longitudinal stress in the CFRP, shear stress in the adhesive layer and the first principal stress in the concrete at the crack tips of the retrofitted RC beams with cracks at different locations are analyzed. The results show that when cracks locate at the loading position, the longitudinal stress in the CFRP is the largest and the tensile failure of the CFRP is the most likely occurred.
The Effect of Thermal Prestress on the Deformation of Micromirror Chip Embedded with Through-Silicon Vias
Authors: Yeh Meng Kao , Lu Chun Lin
Published: January 2011

The thermal expansion mismatch problem for a chip due to temperature decrease from processing temperature to room temperature may cause residual stress inside the chip structure. The thermal prestress accumulated and may affect the chip reliability when the chip was subjected to the thermal loading again. In this paper, the effect of thermal prestress on the micromirror chip embedded with copper through-silicon vias (TSVs) was investigated by the finite element method. In analysis, the micromirror chip embedded with TSVs was analyzed first under thermal loading which resulted from temperature decrease between the stress free processing temperature and room temperature. This process produced a thermal prestress in the micromirror chip. The chip was then subjected to a heat source at the bottom while in operation and the heat transfer analysis was used to simulate this situation. Finally, the thermal stress analysis was carried out to obtain the deformation and the stress distribution in the chip. The results show that the thermal prestress had strong effect on the chip reliability and should be reduced as much as possible. This paper proposed a three steps analysis method to obtain the deformation and the stress distribution in the chip, in which the effect of thermal prestress on the chip reliability was evaluated effectively.
Influence of Heat Treatment on Characteristic Behavior of Co-Based Alloy Hardfacing Coatings Deposited by Plasma Transferred Arc Welding
Authors: Deng Hong Xia , Shi Hui Ji , Tsuruoka Seiji , Yu Hui Chen , Zhong Bin
Published: January 2011

The Plasma transferred arc welding (PTAW) is widely used for hardfacing components exposed to severe conditions. Without post welding heat treatments, large tensile residual stresses remain in the hardfacing coating, which is detrimental. In this paper, a set of post welding heat treatments was evaluated for the heat-resistant steel substrate – Co-based alloy hardfacing coating system. Microstructural and mechanical properties, including the chemical phases of coating surface, the microstructure of coating surface, the Vickers hardness and the residual welding stress, were investigated before and after the heat treatments. Results revealed that during the heat treatments, some elements reprecipitated and the secondary carbide Cr23C6 was formed. After the treatments, a more regular structure and a higher Vickers hardness were obtained. Moreover, the tensile residual stresses in the coating decreased significantly. Therefore, it can be inferred that the post welding heat treatments employed in this paper were proper for this material system.
Numerical Simulation of Reflective Crack Forming in Semi-Rigid Asphalt Pavement Subjected to Traffic Load
Authors: Yu Xin , Du Yin Fei
Published: January 2011

Reflective crack is one of the major technical problems in highway with semi-rigid base, studying its formatting mechanism is of great significance. By means of a numerical analysis method named RFPA, formatting process of reflective crack such as initiation and expansion was studied in asphalt pavement with semi-rigid base. Two-dimensional model of asphalt pavement with cement-treated base was established based on mechanical parameters, thickness and homogeneity of commonly used structural layer in china, symmetrical and non-symmetrical load were both considered, and crack of cement-treated base was set before loaded. First, reasons for crack initiation were studied below the bottom layer subjected to different types of loads. The conclusion showed crack under symmetrical load mainly due to pull destruction while crack under non-symmetrical load mainly due to shear failure. Then, crack expansion in asphalt layer subjected to different load numbers with different homogeneity material was studied. The result showed that with the increase of the load numbers, the deformation in the same level deformation grows continuously. Different homogeneity level of layer material has an important influence on crack expansion; higher homogeneity has better regularity.
Large Scale Elasto-Plastic Analysis Using Domain Decomposition Method Optimized for Multi-Core CPU Architecture
Authors: Kawai Hiroshi , Ogino Masao , Shioya Ryuji , Yoshimura Shinobu
Published: January 2011

To solve a large scale elasto-plastic dynamics analysis of a complicated structure, such as a seismic analysis of a nuclear power plant and a skyscraper, a new implementation strategy for a parallel finite element code, suitable on a parallel supercomputer with modern multi-core / many core scalar CPUs, has been required. In this work, we propose a new design and programming style to optimize the performance of a parallel finite element code based on the domain-decomposition method (DDM) on multi-core CPUs, considering their cache hierarchy. Instead of a traditional, memory access-intensive approach, DS (Direct solver-based matrix Storage), two new matrix storage-free approaches, DSF (Direct solver-based matrix Storage-Free) and ISF (Iterative solver-based matrix Storage-Free), are proposed. Our new DSF/ISF-based DDM solver is not only more efficient in memory usage but also comparable in computational time against existing DS-based DDM solvers on multi-core CPU architectures.
Experimental Determination of Fatigue Life of Automotive Jounce Bumper
Authors: Sidhu R.S. , Ali Aidy , Hassan M.R.
Published: January 2011

It is evident that most rubber components in the automotive industry are subjected to repetitive loading. Vigorous research is needed towards improving the safety and reliability of the components. The study is conducted on an automotive rubber jounce bumper with a rubber hardness of 60 IRHD. The test is conducted in displacement controlled environment under compressive load. The existing models by Kim, Harbour, Woo and Li are adopted to predict the fatigue life. The experimental results show strong similarities with the predicted models.
Elastic-Plastic Analysis of Surface Crack in Round Bars under Torsion
Authors: Ismail Al Emran , Ariffin Ahmad Kamal , Abdullah Shahrum , Ghazali Mariyam Jameelah , Daud Ruslizam
Published: January 2011

An elastic-plastic finite element analysis (FEA) is used to determine the J-integral around the crack front of 3-dimensional semi-elliptical surface crack in a round bar under torsion loading. Crack geometries are based on the experimental observation. The present model is validated using the SIF under bending loading since no suitable SIF for torsion is available. Lack of numerical solution of elastic and plastic stress parameters under torsion are found. The FE J values are normalized by dividing with the estimation J value using a reference stress method. It is found that higher J values are obtained for deep cracks and the maximum J changed from the deepest point along the crack front to the outer point at the free surface when a/D > 0.2. J values can be estimated for all type of crack geometries under consideration with a correction factor, h1.
Newly Designed Adhesive Joint for Torque Loaded Tube
Authors: Akmal Jamiatul , Puja Ign Wiratmaja , Brodjonegoro Satryo S. , Suratman Rochim , Suweca I. Wayan
Published: January 2011

Adhesive joint is commonly applied to CFRP/GFRP composite tube, however, its failure rate is still high and this will limit the use of composite tube for industrial purpose. The literature study showed that the stress distribution at the joint, when loaded, is not evenly distributed and creates stress concentration at the edges. Attempts have been made by researchers to improve the joint design so that the stress would be more evenly distributed and minimize stress concentration, however, the improvement has been very limited. In this work, a comprehensive parameter study has been performed to observe the properties of adhesive joint of torque loaded tube. Based on the observation, a new type of adhesive joint is proposed which successfully reduces the stress concentration along the joint during torque loading. The analysis was performed using finite element method.
Effect of Ni Content on Dissolution Properties of Cu in Molten Sn-Ag-Cu-Ni-Ge Alloy
Authors: Watanabe Hirohiko , Nagai Marie , Osawa Tsutomu , Shohji Ikuo
Published: January 2011

Dissolution properties of Cu in molten Sn-Ag-Cu-Ni-Ge alloys have been investigated. In particular, the effect of the Ni content in the alloys on the dissolution properties has been examined. Moreover, the dissolution properties have been compared with those of Sn-Ag and Sn-Ag-Cu alloys. To investigate the dissolution rate of Cu in molten alloys, Cu wires were dipped in molten alloys heated at 250, 270 and 290°C. Dissolution thickness of Cu wire is proportional to dipping time regardless of alloy type. The dissolution rates of Cu follow the order Sn-Ag > Sn-Ag-Cu > Sn-Ag-Cu-Ni-Ge. In Sn-Ag-Cu-Ni-Ge alloys, the dissolution rate of Cu decreases with increasing the Ni content. In cases of Sn-Ag and Sn-Ag-Cu alloys, a thin Cu-Sn compounds layer forms at the interface between Cu and the alloy and dissolution of Cu does not proceed uniformly. On the contrary, a thick reaction layer, which consists of granular Cu-Ni-Sn compounds, forms at the interface between Cu and the Sn-Ag-Cu-Ni-Ge alloy. Since the reaction layer inhibits dissolution of Cu in molten alloy, the dissolution rate slows down and dissolution of Cu proceeds uniformly in the Sn-Ag-Cu-Ni-Ge alloys.
Numerical Simulation and Experimentation of Warm Metal Powder Compaction Process
Authors: Rahman Mujibur M. , Tarlochan F. , Singh Ramesh , Ariffin Ahmad Kamal , Nor S.S.M.
Published: January 2011

Powder compaction at elevated temperature or known as warm compaction is a process of producing green compacts from metal powder, which is generally conducted between the ambient and the recrystalization temperature of the main powder constituent. Even though, warm compaction was initiated at around 1998, not a lot of information can be found in the literature especially on the numerical simulation of the process. Therefore, this paper presents the simulation of warm metal powder forming process by using the developed computer code. The Elliptical Cap yield model has been used to represent the deformation behaviour of the powder mass during the forming process at above ambient temperature. The material properties of powder mass, i. e., friction coefficient, elastic index, and plastic index, at different forming temperature, are established through warm compaction experiment. The simulation was conducted to generate a green compact of a plain bush component. Some numerical simulation results were validated through experimentation, where a good agreement was found between the numerical simulation and the experimental results.
Dynamic Response of Metallic Square Honeycomb Sandwich Plate Subjected to Blast Loading
Authors: Wang Tao , Qin Qing Hua , Wang Tie Jun
Published: January 2011

Metallic sandwich plates have been widely used in blast-resistance structures due to the excellent capacity of energy absorption. In this work, dynamic response of square honeycomb sandwich plates is investigated using LS-DYNA. The effect of mass of TNT charge on the deformation and on internal energy of square honeycomb sandwich plate is numerically analyzed. The relationship of deflection, as well as internal energy and the mass of TNT charge is obtained. The performance of square honeycomb sandwich plate is compared with monolithic solid plate with the same mass and blast loading. During the response of sandwich plate, the deformation includes local dent of upper face sheet, overall bending and stretching of both face sheets and buckling of square honeycomb core while the deformation of monolithic solid plate is involved in overall bending and stretching. It denotes that square honeycomb sandwich plate has better capacity of resistance-deformation and energy absorption than that of monolithic solid plate with the same mass and the same blast loading.
Experimental Investigation on Mechanical Behavior of Moso Bamboo Vascular Bundles
Authors: Li Hong Bo , Shen Sheng Ping
Published: January 2011

Bamboo is a typical natural fiber reinforced composite material with superior mechanical strength and toughness. As a typical hierarchical material, the macroscopic properties of bamboo are determined by its microscopic structure. The vascular bundles are the reinforce phase in bamboo composite. There was little research on the variation of mechanical properties of bamboo vascular bundles. In this work, the mechanical properties of Moso vascular bundles along the axial direction were investigated by tensile test. It is shown that the longitudinal Young’s modulus and strength of the Moso vascular bundles are linearly increased from inner zone to outer surface.
Evaluation of Plastic Deformation and Fracture Behaviors by Thermal Image Technique
Authors: Sakamoto Hidetoshi , Shi Jian , Ohbuchi Yoshifumi , Yamamoto Mitsuharu
Published: January 2011

Failure of mechanical members largely depends on the size and the development of plastic deformation from the strain concentration parts. In order to evaluate this plastic deformation of mechanical members, we pay attention to the surface temperature that is generated by plastic deformation. Most of the plastic energy exhausted by plastic deforming is converted into heat. Therefore, the heat generation represents the macroscopic plastic deformed intensity. In this report, the tensile deformation tests by using the plate specimen with a center crack were performed and the distributions of surface temperature under the plastic deformation and crack propagation were measured by the thermocouple and the infrared thermo camera. Furthermore, FE elasto-plastic analysis couples with transient heat conduction was performed. The analytical results were good agreement with the experimental ones and it was shown that the infrared thermography method was effective non-contact measurement system as the macroscopic evaluation of the plastic deformation.
Main Crack Propagation Behaviour of RC Beams Strengthened with CFRP under Fatigue Load
Authors: Deng Jun , Huang Pei Yan
Published: January 2011

The fatigue performance and durability of the reinforced concrete (RC) beams strengthened with fibre reinforced polymer (FRP) laminates is an advanced research topic in civil engineering. The crack propagation life is the dominant part of the whole fatigue life of the cracked RC members strengthened with FRP laminates under cyclic loads. In this paper, a theoretical and experimental study was conducted to investigate the rule of the fatigue crack propagation of the RC beams strengthened with carbon FRP (CFRP) under constant cyclic bending load. A total of 5 RC beams with sizes 1850×100×200mm strengthened with CFRP were tested. The results show that it is possible to divide the process of the crack propagation into three distinct phases, including crack initiation and then quickly propagation (Phase I), stable propagation and then rest (Phase II) and unstable propagation (Phase III). In accordance with Paris-Erdogan Law, a semi-empirical equation was developed to predict the crack propagation rate. The empirical coefficients of the equation were obtained from the fatigue test results. To validate this equation, the predicted fatigue life of crack propagation calculated by it is compared with the data obtained from tests. It shows the agreement is good.
Mathematical Modeling for Longitudinal Displacement of a Straight Continuously Welded Railway Track and its Numerical Implementation
Authors: Manap Abreeza
Published: January 2011

A mathematical model of the longitudinal flexibility of a continuously welded railway track and the methodology for the analysis of the longitudinal displacement of rails under the effects of passing trains is developed to investigate the longitudinal behavior of rails. The purpose of this analysis is to explore the changes of longitudinal stress distribution in the rails due to mechanical loading applied by a travelling train. A half track system is used to derive the equations required to obtain the magnitude of deflection and force of rails and these values are scaled to produce the displacement pattern using the method of superposition. The mathematical model is translated into MATLAB and validation of the program is verified through comparisons of displacement patterns generated by a computer software LONGIN. Analysis of a straight track due to train braking was performed over a track length of 1000 m. The longitudinal displacement obtained showed that maximum longitudinal displacement occur in the middle of the track at the distance of 570 m which is in direct agreement with the published result.
Auto Adjust Masses of Automotive Structures with Desired Centre of Gravity
Authors: Afshar Reza , Ali Aidy , Barkawi Sahari B. , Bayat Mehdi
Published: January 2011

In this study a subroutine was developed and added in the pre-processing module of the frame work of commercial package of ANSYS to distribute the extra masses according to specific assigned centre of gravity (COG). The work further calculate the first bending and torsional natural frequencies of the simplified body in white (BIW) model of automotive in order to maximize these frequencies with final mass constraint. It is found that adding the extra masses symmetrically about longitudinal axis helps to improve the first bending and torsion natural frequencies. However, removing the mass along this axis leads to have higher values in the case of first bending and natural frequencies.
Investigation on Behavior of Rock-Socketed Retaining Piles for Deep Excavation
Authors: Liu Xiao Li , Zhou H.
Published: January 2011

In the soil-rock mixed areas where the soils overlie on the rock layer, the rock-socketed retaining piles have been widely used for deep excavations. Up to date, little attention has been paid to performance of the rock-socketed piles used for deep excavation. Therefore, using the two-dimensional finite element program, Plaxis2D, a typical deep excavation engineering supported by rock-socketed piles with the whole embedded portion in rock is analyzed to investigate behavior of the rock-socketed retaining piles in detail. Computation results have shown that for rock-socketed retaining piles used in deep excavations, there exists an ultimate or a maximum rock-socketed depth which can be estimated by the pile diameter. For the ultimate rock-socketed depth, in the final excavation step, the first zero bending moment point of the rock-socketed part of the pile generally locates near the top surface of the rock layer. When the excavated surface is located at the top surface of the rock layer, the corresponding shear force distribution of the rock-socketed pile has an extremum at the same position.
Flexural Wave Localization in Randomly Disordered Periodic Beams with Axial Load
Authors: Wang Yi Ze , Li Feng Ming , Kishimoto Kikuo
Published: January 2011

In this paper, the flexural wave propagation and localization in randomly disordered binary periodic beams with the axial load are studied. Based on the continuity conditions, the transfer matrix between the constitutive unit cells is derived. The expression of the localization length in the disordered periodic system is presented. Numerical calculations are performed to illustrate the localization characteristics of the flexural wave. The effects of the axial load on the band gap structures and the localization properties are discussed. From the results, we can observe that the properties of the pass band and stop band for the perfect system can be tuned by the axial load. Moreover, the localization properties of the flexural wave will be strengthened by the higher disordered degree.