bluuebunny/crossref_metadata_2025 huggingface dataset:
Fluid-Structure Coupled Analysis Using Enriched Free Mesh Method
Authors: Nagaoka Shinsuke , Nakabayashi Yasushi , Yagawa Genki
Published: January 2011

Almost all the phenomena occurring around us are the coupled phenomena. In the field of numerical analysis, it is difficult to perform coupled analysis. Because, there are a lot of problems and these problems make coupled analysis difficult, so we have to resolve these problems to perform analyses with considering the coupling effect. At present, as the popularity of numerical analysis rising along advancement in computer performance, demand of numerical analyses with incorporating coupling effects will further increase. In this research, we propose a new fluid-structure coupled analysis method using SUPG/PSPG stabilized FEM and Enriched Free Mesh Method to eliminate a lot of problems occurring in the process of coupled analysis. As the feature of our proposed method, linear triangular elements are only used in the analysis.
Corrosion Detection in Concrete Structure Including Layered Rebar
Authors: Suga Kazuhiro , Minagawa Koichi , Kikuchi Masanori , Aoki Shigeru
Published: January 2011

This study presents a mesh generation technique considering the measurement accuracy of the potential on an inverse analysis using the boundary element analysis. We evaluate the effects of the distance between layered rebar and corrosion size on measured potential distribution on the concrete surface, and then propose a technique to select reasonable and efficient size of boundary element. A numerical simulation demonstrates the validity and efficiency of the proposed technique.
Corrosion Prediction under Flow Field
Authors: Suga Kazuhiro , Moteki Taro , Kikuchi Masanori
Published: January 2011

This study evaluates effects of the diffusion layer thickness and the share stress on metal surface for the polarization curve under flow field on metal corrosion. We measure the polarization curves under the different diffusion boundary layer thickness and the wall share stress. Metal surface conditions are observed from microscopic and macroscopic view points to evaluate tendencty of corrosion and shape of corrosion product.
Low Velocity Impact Analyses of Prismatic Columns Using Finite Element Method
Authors: Jusuf Annisa , Allam Fajri Syah , Dirgantara Tatacipta , Gunawan Leonardo , Putra Ichsan Setya
Published: January 2011

This paper presents the study of prismatic columns of different cross sections subjected to low velocity impact, which are commonly used as energy absorber components in vehicles. The impacts of the columns were numerically analyzed using FEM. Four cross sections were considered, i.e. square, hexagonal, octagonal and circular. For each cross section, columns with several combinations of perimeters and thicknesses were analyzed. The results showed that, for columns with equal perimeter and thickness, those with circular cross sections have the highest mean crushing force and those with square cross sections have the lowest crushing forces. Furthermore, keeping all other parameters constant, columns with thicker wall have significantly higher crushing force while columns with longer perimeter have only slightly higher crushing force. This parametric information will be very useful for modern automotive industry in designing front longitudinal members within an acceptable safety level.
Prediction of External Stability for Geogrid-Reinforced Segmental Walls
Authors: Kasa Anuar , Chik Zamri , Mohd Raihan Taha
Published: January 2011

Prediction of external stability for segmental retaining walls reinforced with geogrid and backfilled with residual soil was carried out using statistical methods and artificial neural networks (ANN). Prediction was based on data obtained from 234 segmental retaining wall designs using procedures developed by the National Concrete Masonry Association (NCMA). The study showed that prediction made using ANN was generally more accurate to the target compared with statistical methods using mathematical models of linear, pure quadratic, full quadratic and interactions.
Finite Element Analysis on the Stress Intensity Factor under Combined Bending and Torsion Loading
Authors: Ismail Al Emran , Ariffin Ahmad Kamal , Abdullah Shahrum , Ghazali Mariyam Jameelah , Abdulrazzaq M.
Published: January 2011

The stress intensity factor (SIF) under the combined bending and torsion loading were studied using a finite element (FE) analysis ANSYS. A 20-node iso-parametric element was used to model the crack tip and the square-root singularity of stress/strain was employed by shifting the mid-side node to the ¼ position to the crack tip. Different crack geometries and loading ratios were used and due to the non-symmetrical analysis involved, a full FE model was developed and analyzed. Remotely applied bending and torsion moment were subjected to the FE model and the SIF were then calculated along the crack front under such loadings. The SIF calculated using the finite element analysis (FEA) was compared with those results obtained using an effective combined SIF method. According to the comparisons, the discrepancies were dependent on the normalized coordinate, x/h, the relative crack depth, a/D, the crack aspect ratio, a/b and the loading ratio, .
Prediction of Residual Stress Relaxation of Shot Peened 2024-T351 Aluminum Alloy: Part 1
Authors: Zaroog Omar Suliman , Ali Aidy , Barkawi Sahari B.
Published: January 2011

It is important to account for residual stress relaxation phenomenon in the design of the component. Specimens of 2024-T351 aluminium alloy were used in this study. The specimens were shot peened under three different shot peening intensities. Cyclic tests for two load magnitudes were performed for 1, 2, 10, 1000 and 10000 cycles. Residual stresses, microhardness and the cold work percentage were measured at initial state and after each loading cycle for the three shot peening intensities and for the two loads. The study revealed that most of the drop in the residual stress, microhardness and cold work happened in the first cycle are dependent on the applied load.
Experiment Research for Fracture Toughness of PAN-Based Carbon Fibers
Authors: Zhang Bo Ming , Wu Yu Fen
Published: January 2011

For the sake of the carbon filaments’ fracture toughness, using the focused ion beam (FIB) to etch the carbon fibers and got different tensile strength, and all specimens were stretched on an Instron-type filaments testing machine and got the samples’ tensile strength, The crack-to-mirror size ratio was assumed as a constant, In virtue of Griffith fracture theory, Fracture toughness (KΙC) of representative high-strength type PAN (polyacrylonitrile)-based carbon fibers, Torayca T300 and T800, were estimated to be 1MPam1/2 from the tensile strength vs. fracture mirror size relation.
Numerical Study on Self-Consistency Centering Process of Periodic Symmetric Struts Support
Authors: Hai Ji Zhe , Gheni Mamtimin , Liu Wei Bing , Chen Wei , Yu Lie
Published: January 2011

In this paper，the simplified three-dimensional model of Periodic Symmetric Struts Support (PSSS) was established, which is applied to a certain type of gas turbine. The software of computational fluid Dynamics (CFD) and the standard k-ε turbulence model are used in the numerical simulation．To simulate the coupling problems of fluid and solid，the numerical models by considering the heat transfer problem coupling with the solid and fluid have been developed．The internal flow field in PSSS was numerically simulated by an effective method for solving integrated coupling problems. The temperature field and thermal deformation rule of the PSSS was obtained. Through comparison coordinate values of the checked points before and after thermal deformation, the impact of thermal deformation on bearing center level height under temperature load was studied. The centering process of the PSSS at high temperature state was verified.
Earthquake Damage Assessment to Entire Urban Building
Authors: Fu Rong Chang , Cetre Jean Pierre , Jin A Fang
Published: January 2011

Making Aigle in Switzerland as a case to assess earthquake damage to entire urban building, by studying the history of architecture and city planning of entire urban, we found that entire urban can be divided into two urban areas. One area is upstream urban of railway station, which was mainly developed around old urban, and the other area is lower urban of railway station, which was mainly developed after 1950s. Developing stages of the two areas are different. In each urban area, a study area is selected and balanced construction units of each building in the study area are calculated. Based on this, earthquake damage to entire urban building is calculated with European Macrosesmic Scale 1998 (EMS-98). To advance precision of assessment, in this article, relationship between type of structure of building and construction date is established first, which makes it easy to precisely determine type of structure of building according to construction date of building. It advances precision of earthquake damage assessment to building. There are 7900 residents in Aigle, the period of earthquake, whose seismic intensity is Grade VII, is 500 years. If earthquake, whose seismic intensity is Grade VII, occurs, it is possible that about 236 persons will injury badly or die and total property loss may be 117,720,000 Suisse Franc.
Application of Damage Model in Stability Analysis of ShuangjiangKou Underground Caverns
Authors: Xiang Lu , Zhu Wei Shen , Ma Qing Song , Zhou Kui
Published: January 2011

A damage constitutive model was established to evaluate the stability of jointed rock masses around the underground caverns of Shuangjiangkou Hydropower Station. In this model, a second-order damage tensor was formulated to describe the initial geometric imperfection of jointed rock masses. A failure criterion for crack coalescence and a damage evolution equation were proposed by considering the secondary cracks induced by excavations according to the fracture mechanics principles. A subprogram under the framework of FLAC-3D was developed for the damage constitutive model and the damage evolution equation. The model and program were then applied in the stability assessment for the Shuangjiangkou underground cavern group.
Effect of Aging and Protective Coating on the Corrosion Behavior of 6061 Al / SiCp Composite in Chloride Solutions
Authors: Rajasekaran S. , Udayashankar N.K. , Nayak Jagannath
Published: January 2011

Metal matrix composites considered especially for marine application are typically aluminum-based. Utilization of the composites in marine environments requires adequate corrosion resistance. In this work, the effect of aging and aluminum as resistive coating on the corrosion behavior of 6061 Al / SiCp composite in 1N and 3.5N NaCl solution in the temperature range of 300C-500C is studied by means of electrochemical techniques, scanning electron microscope (SEM) and weight loss measurements. Aging results in precipitation of intermetallics in the matrix, this in turn leads to galvanic and pitting corrosion. Pitting initiation and propagation as the main corrosion mechanism was driven by the aging kinetics which is ruled by the reduction in the retained vacancy concentration and at the same time by dislocation density due to the presence of SiCp. Sputtered aluminum coating on the composite effectively resists the pitting initiation and propagation and hence corrosion process. Also the intermetallic precipitates are unexposed to the Chloride solution by the presence of aluminum coating. Hence aluminum coating acts as corrosion resistive coating for the 6061 Al / SiCp aged composites.
Calculation Stress Intensity Factor for Asphalt Pavement Basing on Weight Function Theory
Authors: Yu Xin , Luo Rui
Published: January 2011

Under the continuing action of temperature stress and load vehicle, the crack in cement stabilized aggregate base can easily reflect up into the asphalt surface layer, affecting driving condition and then affecting the fatigue life of pavement. On the basis of fracture mechanics, taking center crack loaded with uniform tensile stress as study state, methods were derived to calculate the stress intensity factor (abbreviated in the following “SIF”) of the crack at the bottom of asphalt layer using weight function theory and method of Petroski and Achenbach. Through the comparison of different SIFs under different conditions, factors affecting the SIFs such as crack length, load conditions, modulus ratio between base and surface layer and different jointed conditions were studied. To facilitate comparison, taking completely smooth and completely continuous as study boundary conditions. According to calculation results, factors mentioned above all influence the SIF values of the crack at the bottom of asphalt layer greatly, among which jointed condition between base and surface layer has the most important influence. The SIF values of the completely smooth interface is several times that of the completely continuous interface. We can take measures to improve the jointed condition between the asphalt surface layer and the cement stabilized aggregate base thus can reduce reflection crack effectively.
Finite Element Analysis of Indentation Cracks for Brittle Materials under Static Loading
Authors: Souiyah Miloud , Muchtar Andanastuti , Ariffin Ahmad Kamal
Published: January 2011

The indentation method is able for use in determining the fracture properties of materials. In the present work, a source code programme for two-dimensional finite element method has been applied to simulate cracking behaviour during indentation on brittle specimens under static loading conditions. The study also aims to predict the crack propagation trajectories under Linear Elastic Fracture Mechanics (LEFM). The source code is written in FORTRAN language. The FE mesh is generated using an advancing front method, where the generation of the background mesh and the construction of singular elements are also added to this developed programme to realise the fracture analysis. In evaluating the accuracy of the crack path predictions, the results are compared and validated with the sets of experimental data of relevant published research work. Upon comparison, it is proven that this developed source code programme is capable of demonstrating the crack indentation in terms of predicting the crack trajectories as well as the evaluation of the stress intensity factors.
Propagation Behavior of Interfacial Fatigue Cracks in RC Beams Strengthened with Pre-Stressed FRP
Authors: Xie Jian He , Huang Pei Yan , Liu Feng , Guo Yong Chang
Published: January 2011

Debonding failure mode usually occurs in the concrete structure flexural strengthened with fiber reinforced polymer (FRP) under cyclic loading. This paper presents an experimental investigation into the fatigue behavior of the FRP-concrete interface of reinforced concrete (RC) beams strengthened with prestressed FRP. 8 small-scale beams were tested under three-point bending cyclic loading. The propagation behavior of the fatigue interface cracks is addressed, and curves showing the growth law of interface cracks are presented. Results from these tests show that the propagation process of interface cracks had three stages, including rapid, stable and unstable growth. The stable propagation phase experienced the most part of the whole test, and the failure mode of all failed beams was debonding following the fatigue fracture of the tensile steel bars. In addition, the influence of FRP prestressing level on the fatigue lives of strengthened beams is discussed, and an empirical formula is developed to predict the fatigue lives of such members. The results show that the fatigue life increases with the prestressed level of FRP. This study provides an insight on the potential long-term performance of FRP-strengthened beams submitted to fatigue loading conditions.
Optimising Real-Time Performance of Genetic Algorithm Clustering Method
Authors: Khairir Muhammad Ihsan , Mohd Nopiah Zulkifli , Abdullah Shahrum , Baharin Mohd Noor
Published: January 2011

This paper presents the optimisation of real-time performance of the genetic algorithm clustering method. This performance optimisation concerns the population diversity and limitation and is based on actual runtime of the algorithm. A real-time ticker is incorporated into the algorithm for actual runtime measurement. For population diversity and limitation, a controlled k-means analysis is performed on the population of solutions to determine its diversity. Achieving a less diverse population in less amount of time without sacrificing the accuracy of the algorithm will help reduce the time-complexity of the algorithm, thus opening up the potential for the algorithm to cluster data in higher dimensions. Results from this study will be used for improving the method of clustering fatigue damage features of automotive components using genetic algorithm based methods.
Durability Assessment of Quad Flat No-Lead Package Using Signal Analysis
Authors: Yunoh Mohd Faridz Mod , Abdullah Shahrum , Jalar A. , Abdullah L. , Abdullah M.F.
Published: January 2011

This paper presents a methodology to determine the durability of Quad Flat No-Lead (QFN) package. The QFN package is useful for improving the reliability of the package. A mechanical fatigue test namely three points bending cyclic test and signal analysis were proposed in this paper. The three points bending cyclic test method is a test assembly that supports a specimen on two anvils or rollers, and symmetrically loads the specimen on the opposite surface with an anvil or roller using micro-tester machine. For strain signal collection, a strain gauge was connected to the dynamic data acquisition system, and it was used for each tested QFN package for determining the response of the captured cyclic strain signal. It was found that the sinusoidal amplitude pattern of signal response has been obtained during the constant three points bending cyclic test. The obtained response signals were then analysed using the Power Spectral Density.
Study on Joint Deflection of Existing Joint Plain Concrete Pavement upon Adoption of Hot Mixture Asphalt Overlay
Authors: Shan Jing Song , Guo Zhong Yin
Published: January 2011

When HMA (hot mixture asphalt) is used to remedy functional or structural deficiencies of existing JPCP (joint plain concrete pavement), reflection cracking is a major distress mode in HMA overlay. The basic mechanism of reflection cracking is the propagation of cracks through the overlay due to deflection difference in the joints vicinity of the existing pavements. In this paper the model of JPCP is created by three finite element method and the relationship between joint deflection difference and effects such as base modulus, elastic coefficient of spring elements is discussed. Based on the model of JPCP, the finite element model of asphalt overlay is created then and shear stress concentration phenomenon is found at the bottom of HMA where is just above the joint of JPCP. So, the rule of the shear stress at the bottom of HMA with deflection difference at the joint of JPCP is studied.
Performance of the Casing-Plug Joints of Square Steel Tube Structures
Authors: Jiang Xiu Gen , Xu Ning , Shi Xu Dong , Wu Yu Huan , Chen Xing Hua , Ju Jin San
Published: January 2011

The performance of the casing-plug joint, including load carrying capacity, stiffness, failure modes, and its influence factors of the casing tubes set inside and outside of the main tubes are analyzed by simulating square steel tube casing-plug joints structures with ANSYS software in this paper. The formulas of the optimum l/L for the joints with the size of the main tube cross-section 200mm× 200mm are given in this paper.
Stability Analyses of an Earth Dam Using Limit Equilibrium and Finite Element Methods
Authors: Yunus Ahmad Anwar Mohd , Kasa Anuar , Chik Zamri , Mohd Raihan Taha
Published: January 2011

The objective of this research is to study the relationships between the stability of earth dam and its soil strength parameters. The soil strength parameters include cohesion, unit weight of soil and angle of friction. GeoStudio, commercially available software, was used to obtain the overall factor of safety using limit equilibrium method (LEM) and finite element method (FEM). Tables to show the relationships among soil strength parameters for factor of safety 1.0 and 1.5 are presented in this paper.
Fatigue Damage Mechanism Analyses of Oriented Sheets of Polymethyl Methacrylate Glasses
Authors: Guo Wei Guo , Zhang Xiao Qiong , Su J.
Published: January 2011

To understand the damage mechanism and obtain the fatigue life of the oriented sheets of polymethyl methacrylate (PMMA) glasses, the quasi-static compression tests and the constant amplitude fatigue testing with two notch stress concentration factors are carried out respectively, using the CSS44100 electromechanical universal materials testing machines and a MTS servohydraulic testing machine. The damage region and fracture section of the deformed and failed sheet samples are examined with the aid of an optical microscopy. The results show that, 1) the oriented PMMA glasses drawn through vertical bi-direction have remarkable thermomechanical anisotropic characteristic, that is, it has the higher hardness and strength along the normal direction of the sheet panel, it will burst out and scatters into bigger pieces under the perforation; 2) the S-N curve of the oriented sheet specimens shows that its fatigue life is not sensitive on the notch at lower amplitude stress levels; and 3) the crack initiation of the oriented PMMA glasses often originates the interbeds area or mid region of the notch edge under fatigue cycle loading.
Effect of Boundary Conditions on Transient Response of Sandwich Plates with Electrorheological Fluid Core
Authors: Rahiminasab Jafar , Rezaeepazhand Jalil
Published: January 2011

Electrorheological (ER) fluids are a kind of smart material whose rheological properties can be controlled by an external electric field. In the present paper, the transient vibration of a rectangular three layer sandwich plate with electrorheological fluid core is analyzed based on the classical plate theory. The Bingham plastic model is used to consider the post-yield behavior of ER fluid. The structure is modeled using a finite element method. Hamilton’s principle is employed to derive the finite element equations of motion. The constant average acceleration scheme is used to integrate the equations of motion. The effects of change in electric field and core thickness on the structure settling time and its natural frequencies are studied for various boundary conditions. The results show that the thickness of the core layer and the electric field strength has significant effects on damping behavior of the sandwich plate. When the applied electric field increases a linear decay in transient response of the structure is observed. It is also found that the electric field changes have no influence on the system natural frequencies.
Structural Similitude between Vibration Response and Flutter Boundary of Cross Ply Composite Plates
Authors: Yazdi Ali Amin , Rezaeepazhand Jalil
Published: January 2011

This paper presents the similarity conditions between aeroelastic instability (flutter) and the free vibration frequency of cross-ply laminated plate. The method is based upon the direct use of governing equation of the system. Both complete and partial similarities are discussed. This approach, the natural frequency analysis of models and prototype is used to predict the flutter boundary of laminated plate. The results present herein indicate that there are some constrains such as geometry of the model, model material, and stacking sequence of laminates in designing a model with complete similarity. As working with complete similar scale model is usually difficult, some certain types of distortion (distortion in number of plies, and stacking sequence) are considered. According to the results, cross ply composite models can be found which have this ability to predict flutter boundary of the prototype accurately using free vibration data.
Stress Corrosion Cracking Analysis under Thermal Residual Stress Field Using S-FEM
Authors: Kikuchi Masanori , Wada Yoshitaka , Shimizu Yuto , Li Yu Long
Published: January 2011

Fracture in heat affected zone (HAZ) in welding has been a serious problem for the integrity of machines. Prediction of fracture behavior due to the residual stress field in HAZ is important. In this paper, S-Version FEM(S-FEM) is applied to simulate the crack growth under thermal and residual stress fields. For evaluation of stress intensity factor, virtual crack closure integral method (VCCM) is employed. In order to confirm the validity of this analysis, numerical results are compared with previously-reported analytical and experimental results. Then, crack growth analysis in piping structure with welding joint was conducted. The residual stress data was provided by JAEA, Japan Atomic Energy Agency, based on their numerical simulation. Using S-FEM, two- and three-dimensional analyses are conducted, and crack growth behavior under thermal stress field is studied and discussed.
Surface Crack Mesh Generation with Factory Roof under Mixed Mode Loading Using a Tetrahedral Element
Authors: Wada Yoshitaka , Sato Masaki , Orita Yohei , Kikuchi Masanori
Published: January 2011

Recent development of crack propagation analysis is rapidly advanced and its applications are being extended. Usually finite element method is utilized for the analysis. One of the most important tasks is mesh generation which requires fully automated system and no failures. It is very difficult to meet all geometrical and mechanical requirements for a surface mesh generation. Recent studies show a factory roof is easily generated under mixed mode loading. How to generate surface crack tetrahedral mesh without failures and surface crack analysis with factory roof are presented.
Fatigue Data Analysis Using Continuous Wavelet Transform and Discrete Wavelet Transform
Authors: Abdullah Shahrum , Sahadan S.N. , Nuawi Mohd Zaki , Mohd Nopiah Zulkifli
Published: January 2011

The wavelet transform is well known for its ability in vibration analysis in fault detection. This paper presents the ability of wavelet transform in fatigue data analysis starts from high amplitude events detection and it is then followed by fatigue data extraction based on wavelet coefficients. Since the wavelet transform has two main categories, i.e. the continuous wavelet transforms (CWT) and the discrete wavelet transform (DWT), the comparison study were carried out in order to investigate performance of both wavelet for fatigue data analysis. CWT represents by the Morlet wavelet while DWT with the form of the 4th Order Daubechies wavelet (Db4) was also used for the analysis. An analysis begins with coefficients plot using the time-scale representation that associated to energy coefficients plot for the input value in fatigue data extraction. Ten extraction levels were used and all levels gave the damage difference, (%∆D) less than 10% with respect to original signal. From the study, both wavelet transforms gave almost similar ability in editing fatigue data but the Morlet wavelet provided faster analysis time compared to the Db4 wavelet. In comparison to have the value of different at 5%, the Morlet wavelet achieved at L= 5 while the Db4 wavelet at L=7. Even though it gave slower analysis time, both wavelets can be used in fatigue data editing but at different time consuming.
Durability Analysis of an Automobile Coil Spring Using Hybrid I-Kaz
Authors: Ismail Napsiah Binti , Abdullah Shahrum , Nuawi Mohd Zaki , Mohd Nopiah Zulkifli , Lennie Abdul
Published: January 2011

A durability related analysis has been performed using a new statistical-based method, called the Hybrid Integrated Kurtosis-based Algorithm for Z-notch filter (Hybrid I-kaz) Technique. This method provides a two dimensional graphical representation of the signal amplitude and the Hybrid I-kaz coefficient that were used to measure the degree of data scattering. For validation purposes, road tests have been conducted in order to measure the strain and vibration signals on a coil spring. Three road surfaces were used for the road test and data collection purposes. This study used test signals which excited based on three different road surfaces. The 5-mm strain gauge and an accelerometer were fixed on the outer surface of the coil spring for measuring the variable amplitude strain loadings together with the vibration response. The time domain strain and vibration signals were then analysed using global signal statistics and Hybrid I-kaz coefficients. Finally, it was found that the respective coefficients for each signals showed an increment with the total value of strain range and vibration amplitudes.
Application of Precise Integration in Dielectric Layer PBG Structure in a Waveguide
Authors: Yang Hong Wei , Long Lian Chun
Published: January 2011

In this paper, precise integration in a symplectic system is used to analyze the stop-band characteristic of the dielectric layer PBG structure in a waveguide. The transverse section is made discrete by using edge elements. The stiff matrices of a dielectric layer and an air layer can be calculated by precision integration based on Riccati equations in a Hamiltonian system. The export stiff matrices of a period can be obtained by a combination of substructures, and then the whole structure can be solved. The stop-band characteristic of a dielectric layer PBG structure in a waveguide is obtained and the effects of the size of period and the number of periods are discussed. The examples presented show that this method is precise and efficient.
Bird Impact Analysis of Wing Leading Edge Structure Based on SPH Method
Authors: Wan Xiao Peng , Wang Wen Zhi , Zhao Mei Ying
Published: January 2011

In this paper, a new bird model which combined the visco-elastic material properties and Smooth Particle Hydrodynamics (SPH) method has been proposed to simulate the bird features in high-speed conditions. A rigid plate impact test was adopted to compare the reaction of SPH and Lagrangian bird model. Compared with the results of Lagrangian bird model, new SPH model was more in line with the experimental data, and has better computational efficiency. The SPH bird model was further used to bird impacting with the wing leading edge by using finite element program LS-DYNA. Two kinds of leading edge structural enhancement programs have been proposed and carried out simulation of bird impact. Basis of calculation, the design parameters of experimental structure was determined and was produced to wait for final testing.
Crack Closure Behavior under High-Load Ratio for AISI 4340 Steel
Authors: Razzaq M. Abdul , Ariffin Ahmad Kamal , Abdullah Shahrum , Sajuri Z.
Published: January 2011

In this paper, fatigue crack growth rate (FCGR) analyses were conducted on compact specimens of an AISI 4340 alloy to study the behavior over a range in load ratios (0.1 ≤ R ≤ 0.95) and constant maximum stress intensity factor (Kmax) condition. Previous study had indicated that high R > 0.7 and constant Kmax test conditions near threshold conditions were suspected to be free of crack-closure and that any differences were caused by Kmax effects, from threshold to near fracture conditions. Cracks in high-cycle fatigue (HCF) components spend a large portion of their fatigue life near threshold conditions. In order to characterize the evolution of damage and crack propagation during these conditions, fatigue crack growth rate (FCGR) data at threshold and near-threshold conditions are essential in predicting service life and in determining the proper inspection intervals. Fatigue crack growth model, namely the Forman model were examined, this model implicit the effect of R ratio and ease of curve fitting to measured data. The Forman model may be suggested for use in critical applications in studying fatigue crack growth for different load ratios.
Seismic Response Evaluation of RC Tower Connected to Short Rigid Buildings
Authors: Hejazi Farzad , Dalili Mohammad S. , Noorzaei Jamal , Jaafar M.S. , Abdullah A.Ali Abang , Thanoon W.A.
Published: January 2011

In urban construction with the presence of tall buildings adjacent to short buildings, civil engineers have tried to connect low-rise rigid buildings to tall buildings in order to enhance the rigidity of the towers and decrease seismic response induced by earthquake excitation. From recent developments in earthquake energy dissipation systems, the application of viscous dampers for coupling of parallel and adjacent buildings to reduce earthquake effect has been considered by civil engineers, and many investigations have been conducted. In the present study an attempt has been made to evaluate the effect of connecting reinforced concrete towers to short rigid building through viscous damper devices. For this purpose, a 10-story RC tower connected to two short RC buildings by viscous damper was modeled and analyzed under Elcentro (1940) earthquake record excitation by using the finite element technique. In addition, the effect of various viscous damper damping coefficients on seismic response of the tower was evaluated by analyzing the aforementioned tower with various damper damping coefficient to the short building. The results showed improvement of seismic response of the tall building which was supported by short RC buildings through viscous damper device during earthquake. Moreover by increasing damper damping coefficient response of the tower structure the displacement was effectively reduced.
Analytical Concepts for Recent Development in Fatigue Crack Growth under Variable Amplitude Loading. Part I: Qualitative Interpretation
Authors: Nik Abdullah N. , Hafezi M. Hadi , Abdullah Shahrum
Published: January 2011

Understanding effective parameters in fatigue crack growth (FCG) model under variable amplitude loading (VAL) is of eminent importance theoretically as well as experimentally. In response to this necessity, a systematic study of different analytical concepts and loading sequences in order to gain a practical framework has been proposed. The theoretical background related to the fatigue life prediction by using FCG model has been presented. This has shown the rationale of why we need to calculate local stress-strain in the crack tip in developing FCG models which is the main subject of this research.
Thermal Stress and Thermal Cycling Analyses of Microgyroscope Chip Models
Authors: Yeh Meng Kao , Lu Chun Lin
Published: January 2011

The thermal stress and thermal fatigue life for three different microgyroscope chip models were investigated in this paper. The deformation and stress distribution in chip, at interface between microgyroscope and chip, and in the spring of microgyroscope were obtained for three different microgyroscope chip models by the finite element method. The results show that for the simplified model, no obvious differences from linear or nonlinear analyses are obtained and the fatigue life of microgyroscope chip can be predicted with the properly simplified model. Also, the model having the same process in fabricating microgyroscope and carrier has better reliability. This paper provides an effective method for the reliability analysis of microgyroscope chip.
Parallel Eigen Frequency Analysis Using Enriched Free Mesh Method
Authors: Kobayashi Yosuke , Shioya Ryuji , Yagawa Genki
Published: January 2011

The Enriched Free Mesh Method (EFMM) is a Mixed Method using the Hellinger-Reissner principle. A highly accurate stiffness matrix is computed for each local cluster. As a result, the EFMM can compute the high performance structural problem of low-order mode without an increase in the number of DOF. In this research, a large eigen frequency analysis of discrete model of the EFMM is performed using the Lanczos method on a PC cluster environment.
Fatigue Failure Analysis Using the Theory of Critical Distance
Authors: Daud Ruslizam , Ariffin Ahmad Kamal , Abdullah Shahrum , Ismail Al Emran
Published: January 2011

This paper explores the initial potential of theory of critical distance (TCD) which offers essential fatigue failure prediction in engineering components. The intention is to find the most appropriate TCD approach for a case of multiple stress concentration features in future research. The TCD is based on critical distance from notch root and represents the extension of linear elastic fracture mechanics (LEFM) principles. The approach is allowing possibilities for fatigue limit prediction based on localized stress concentration, which are characterized by high stress gradients. Using the finite element analysis (FEA) results and some data from literature, TCD applications is illustrated by a case study on engineering components in different geometrical notch radius. Further applications of TCD to various kinds of engineering problems are discussed.
Solution for Geometrically Non-Linear Elastic Deformation of Simple Frames by a Shooting Method
Authors: Li Shi Rong , Hu Ya Dong
Published: January 2011

Based on an exact geometric nonlinear theory for plane curved beams, geometrically nonlinear equilibrium equations and boundary conditions governing the nonlinear bending of a simple plane frame structure subjected distributed loads were derived. By using the shooting method to numerically solve the boundary value problem of nonlinear ordinary differential equations, large deformation equilibrium configurations of a simple frame with both straight and the curved beam elements subjected uniformly distributed load were obtained. The theory and methodology presented can be used to analyze large deformation of plane simple frames with a variety of geometries and loadings.
Data Fusion of Probabilistic Full-Field Measurements for Material Characterization
Authors: Pan Jan Wei , Cheng Jin Quan , Furukawa Tomonari
Published: January 2011

This paper presents a data fusion technique to model more certain probabilistic full-field strain/displacement measurements for stochastic energy-based characterization proposed by the authors. The proposed technique measures the full-field measurements by using multiple cameras, constructing a Gaussian probability density function (PDF) for each camera, fusing the PDFs and developing the total PDF of the full-field measurements. Since the certainty of measurements is magnified by the use of multiple cameras, the use of multiple well-calibrated cameras could achieve the accuracy which no single camera could attain. The validity of the proposed energy-based characterization and its superiority to the original formulation were investigated using numerical analysis of an anisotropic material, and the proposed technique was found to improve the accuracy significantly with the addition of cameras.
Mechanics of Composite Delamination under Flexural Loading
Authors: Koloor S.S.R. , Abdul-Latif A. , Tamin Mohd Nasir
Published: January 2011

The mechanics of interface delamination in CFRP composite laminates is examined using finite element method. For this purpose a 12-ply CFRP composite, with a total thickness of 2.4 mm and anti-symmetric ply sequence of [45/-45/45/0/-45/0/0/45/0/-45/45/-45] is simulated under three-point bend test setup. Each unidirectional composite lamina is treated as an equivalent elastic and orthotropic panel. Interface behavior is defined using damage, linear elastic constitutive model and employed to describe the initiation and progression of delamination during flexural loading. Complementary three-point bend test on CFRP composite specimen is performed at crosshead speed of 2 mm/min. The measured load-deflection response at mid-span location compares well with predicted values. Interface delamination accounts for up to 46.7 % reduction in flexural stiffness from the undamaged state. Delamination initiated at the center mid-span region for interfaces in the compressive laminates while edge delamination started in interfaces with tensile flexural stress in the laminates. Anti-symmetric distribution of the delaminated region is derived from the corresponding anti-symmetric ply sequence in the CFRP composite. The dissipation energy for edge delamination is greater than that for internal center delamination. In addition, delamination failure process in CFRP composite can be described by an exponential rate of fracture energy dissipation under monotonic three-point bend loading.
Analysis of Stress-Strain Hysteresis Loop and Prediction of Thermal Fatigue Life for Chip Size Package Solder Joints
Authors: Shohji Ikuo , Kobayashi Tatsuya , Tohei Tomotake
Published: January 2011

The aim of this study is to investigate the relationship between the inelastic strain range and the thermal fatigue lives of chip size package solder joints with Sn-Pb and Sn-Ag-Cu solder balls. The inelastic strain range was examined by finite element analysis. In both solder joints, the exponential terms in the inelastic strain range term in the Coffin-Manson equation were evaluated as 1.8 - 2.3. These values are very close to the conventional one used in Sn-Pb and the Pb containing solders. The inelastic strain range is almost proportional to the temperature range in the Sn-Pb solder joint. On the contrary, the inelastic strain range is proportional to approximately the square root of the temperature range in the Sn-Ag-Cu solder joint. The deference depends on the change of the stress-strain hysteresis curve in the thermal cycle.
Numerical Application in Weight Reduction of Lateral Plate of Rescue Robot
Authors: Young Lih Jier
Published: January 2011

In general, weight reduction will always lower the strength of the specimen. The primary purpose of this paper is weight reduction of lateral plate of rescue robot without causing the strength of it by using the Boundary Element Method (BEM). The dynamical loading conditions are performed before and after weight reduction. The numerical results of the stress distribution and the plastic deformation along the center line (interface) of the lateral plate show that the endure limits of the plate before and after weight reduction are almost the same and therefore, will not lower the strength of the plate.
Damage Analysis and Simulation of Rock under High Pressure Waterjet
Authors: Si Hu , Li Xiao Hong , Xie Yan Ming
Published: January 2011

The high pressure waterjet is widely applied for mine industry, mechanical manufacture, environmental engineering, and medicine field due to its particular characteristic. Recently, the application of high pressure waterjet for gas drainage in mine has been receiving increasing attention with the development of exploitative technology. The micro-damage mechanism of coal under high pressure water jet is key to drain gas effectively. Based on damage mechanics and rock dynamics, the paper analyzed the micro-structure deformation and damage of rock and the impulsive effect under high pressure water jet and developed the dynamic model. Further, on the assumption of that rock was homogeneous and isotropic, a computational model was established based on the Arbitrary Lagrangian Eulerian (ALE) fluid-solid coupling penalty function method. The rock damage under high pressure water jet was simulated by the dynamic contact method. The results showed that the damage and breakage of ruck was mainly attributed to impacting effect and was characterized by local effect, and the evolvement of rock breakage went through three stages and the figure of rock breakage trended a funnel. On the whole, numerical results agreed with experimental results.
Effect of Ag Content on Mechanical Properties of Lead-Free Sn-Ag-Cu-Ni-Ge Alloy
Authors: Shohji Ikuo , Arai Ryohei , Ishikawa Hisao , Kojima Masao
Published: January 2011

The tensile properties of Sn-x(x=1, 2, 3)Ag-0.5Cu-0.05Ni-0.005Ge (mass%) alloys were investigated. In addition, the ball shear force was investigated with solder balls and two types electrodes, Cu and electroless Ni/Au plated Cu, to examine joint reliability under heat exposure conditions. Tensile strength of the alloy decreases with decreasing the Ag content. On the contrary, elongation increases with decreasing the Ag content. When the Ag content reduces, primary β-Sn phases are coarsened and eutectic microstructures diminish. The decrease of the eutectic microstructures causes a reduction of the tensile strength. In as-soldered joints with Sn-Ag-Cu-Ni-Ge solder balls and Cu electrodes, the ball shear force increases with increasing the Ag content. However, the ball shear force decreases with increasing heat exposure time. After heat exposure treatment at 423 K for 500 h, the ball shear force is relatively stable at lower values regardless of the Ag content. In the joints with electroless Ni/Au plated Cu electrodes, the ball shear force slightly increases with increasing heat exposure time. Even after heat exposure treatment at 423 K for 500 h, hierarchy of the ball shear force is maintained. The ball shear force becomes high with increasing the Ag content.
Pattern Recognition of Impact in Passenger Car Bumper Using Smart Materials
Authors: Wang Gao Ping , Zhou Pan , Chen Han Xin , Chen Jun
Published: January 2011

All over the world at present, injuries and fatalities from road accidents are a significant problem, especially occurred to pedestrians from passenger cars. Most of the fatal accidents between car and pedestrians prove deadly because of the head to hood impact. This paper aims to develop a bumper to avoid from passenger car’s fatal head impact for pedestrian protection, and most importantly, the impact of different objects with passenger car bumper needs to be recognized. Firstly, a pendulum system is constructed to perform the fundamental research which is concentrated on the response pattern of impact-object simulation tests, and we confirmed the application possibility for the method of discriminable pattern recognition whether impact-object is human-like or not by means of neural networks using smart PZT materials. Finally, the impact characteristics analyses can provide enough pattern recognition indices which can be developed and then used to recognize the impact information by two different neural networks.
Creep Deformation Characteristics of Austenitic Stainless Steel Foils
Authors: Osman Hassan , Tamin Mohd Nasir
Published: January 2011

Creep deformation process of austenitic stainless steel foil with thickness 0.25 mm was investigated. The foil specimen was creep tested at 750oC, 54 MPa to establish baseline behavior for its extended use as primary surface recuperator in advanced microturbine. The creep curve of the foil shows that the primary creep stage is brief and creep life is dominated by tertiary creep deformation. The curve is well represented by the modified theta-projection concept model with hardening and softening terms. Morphology of fractured foil surface reveals intergranular fracture with shallow network of faceted voids. The formation of w-type creep cavities is significant, as revealed by microstructure of ruptured specimen. Composition analysis indicates the formation of carbides, namely, Cr23C6, NbC and Fe3Nb3C.
Research on the Electrolyte Service Life of Treating AZ91D by Micro Arc Oxidation
Authors: Pan Ming Qiang , Di Shi Chun , Chen Tao , Chen Li Guo , Wang Zhen Hua
Published: January 2011

With the development of micro arc oxidation and the growing maturity of the industrialization, the electrolyte service life and stability attract more and more people. In this paper, the electrolyte service life was researched. Under the same technological conditions, it was found that the critical factors affecting the electrolyte service life are the single-processing area and the electrolyte volume. With prolonging the working time of the electrolyte, the gel deposition mass in the electrolyte and the initial voltage always change. The experiment indicates that the electrolyte service life will assume the curve extension when reducing the single-processing area or increasing the solution volume. To some extent, the initial voltage and gel deposition can indicate the active state of the electrolyte, and can be considered as the sign whether the electrolyte service life becomes due.