bluuebunny/crossref_metadata_2025 huggingface dataset:
Surface Hardening of Aluminium-Copper Alloy 2011 by RF Plasma Nitriding Process
Authors: Pongsopa Jiraporn , Visuttpitukul Pattama , Paosawatyanyong Boonchoat
Published: January 2011

In this work, an inductively-coupled rf plasma reactor was utilized in the nitriding process for surface hardness improvement of aluminium-copper alloy 2011. Substrate bias at 400V was used in the pre-sputtering step to eliminate the aluminium oxide on the samples. Plasma nitriding was carried out in a N2-H2 admixture at total pressure of 1 torr. The process length was varied from 9 to 36 hours while the input rf power and substrate temperature were varied from 100 to 300 W and kept at 400 oC, respectively. A negative bias voltage up to 400 V was used in the nitriding process. Glancing incident-angle x-ray diffraction (GIXRD) results showed the hexagonal crystal structure of AlN on samples. The roughness increased slightly when the voltage increase up to 400V and was investigated by Scanning Electron Micrograph (SEM). Electron Probe Microscopy Analysis (EPMA) and Energy Dispersive X-ray Analysis (EDX) were used to detect the N atoms in specimens. Significant increases of surface hardness are observed after plasma nitriding.
Fracture Toughness and Fatigue Crack Growth Behavior of Rail Track Material
Authors: Sajuri Z. , Alang N.A. , Razak Nur Azhani Abd , Aziman M.A.
Published: January 2011

Fracture toughness KC and fatigue crack growth behavior of commuter train’s rail track material used in Klang Valley, Malaysia was investigated. Two different tests were performed in accordance to ASTM E399 and E647 testing procedures using single edge notch bend (SENB) and compact tension (CT) specimens, respectively. The results showed that the average KC value of the rail track material was 51.7 MPa√m. On the other hand, from the fatigue crack growth test, both longitudinal (LD) and short-transverse (TD) direction specimens demonstrated identical Paris’ Law constants C and m of 1.3 x 10-12 m/cycle and 3.54, respectively. Prediction of bending fatigue life of rail track material using the above obtained parameters showed a good agreement with the experimental results.
Variable Amplitude Loading Strains Data Distribution Using Probability Density Function and Power Spectral Density
Authors: Lennie Abdul , Mohd Nopiah Zulkifli , Abdullah Shahrum , Baharin Mohd Noor , Nuawi Mohd Zaki , Ariffin Ahmad Kamal
Published: January 2011

This paper presents a relative study on variable amplitude (VA) strain data distribution using the approach of probability density function (PDF) and power spectral density (PSD). PDF is a technique to identify the probability of the value falling within a particular interval, and a PSD is to measure the power of a signal by converting it from the time domain to the frequency domain. The objective of this study is to observe the applicability of both techniques in detecting the pattern behaviour in terms of energy and probability distribution. For this reason, a set of case study data consist of nonstationary VA pattern with a random behaviour was used. This kind of data was measured by fixing a strain gauge that connected to the strain data acquisition on the lower suspension arm of a mid-sized sedan car. The data was measured for 60 seconds at the sampling rate of 500 Hz, which gave 30,000 discrete points. The distribution of collected data was then calculated and analysed in the form of both PDF and PSD, and they were then compared for further analysis. The findings from this study are expected for determining the pattern behaviour that exists in VA strain signals.
Development of the Auto Mesh Generation Program for a Digital Image Correlation Method
Authors: Tomita Koji , Machida Kenji , Zhang Zu Guang
Published: January 2011

Since the method of performing displacement measurement and stress assessment of material by non-contact comes to capture the spotlight, study of the digital image correlation method which adopted the pattern-matching method for asking for displacement by deformation of a surface speckle pattern has been advanced. When the configuration for an analysis was settled in the rectangle and the square region, the whole-field mesh generation was also possible, but when it became a complicated configuration, the background etc. entered and mesh generation was affected. In order to solve such a problem, even if the object for an analysis was a complicated configuration, it aimed at generating a mesh automatically and obtaining appropriate analysis output in the displacement analysis and stress analysis using the generated mesh. In addition, the validity of the result was verified by the comparison with the finite element method. By this study, the convenience and availability of the digital image correlation method was improved remarkably, and it became clear to become a leading tool in health monitoring.
Hydro-Elastic Vibration of Partially Liquid-Filled or Partially Liquid- Surrounded Composite Cylindrical Shells
Authors: Shao Zhu Shan , Ma Guo Wei , Song Zhan Ping
Published: January 2011

Vibration characteristics of partially liquid-filled or partially liquid-surrounded composite cylindrical shells are investigated in this paper. Using Rayleigh-Ritz energy method and Love’s shell theory, eigenvalue equation of the problem is derived, and the polynomial for natural frequencies of such shells is further obtained. The external work by the hydrodynamic pressure, which is introduced by liquid sloshing, is taken into account in the energy function. Hydro-elastic vibration characteristics of a composite cylindrical shell are studied by using the present method. Effects of liquid level, liquid density, fiber orientation, length-to-radius ratio, and thickness-to-radius ratio on the natural frequencies are analyzed and graphically presented.
Theoretical Investigation into the Wave Propagation in Rock with Single Fracture
Authors: Song Lin , Shao Zhu Shan , Wu Min Zhe
Published: January 2011

Theoretical investigation on incident elastic P-wave transmission across rock fracture is presented by using an optimization method. It’s assumed that the rock fracture is of nonlinear constitutive model for normal deformation, and the hyperbolic elastic model (BB model) is introduced to descript this nonlinear property. Based on the theory of momentum conservation and discontinues condition, wave propagation equation for P-wave transmission across nonlinear fracture is obtained. Parameter studies, including initial normal stiffness, the ratio of given closure to maximum allowable closure and frequency, are carried out and graphically presented.
Experimental Study on Embryo Skeletal Development to Postnatal Growth Process of Rabbit Thighbone
Authors: Mamatrozi Juret , Gheni Mamtimin , Akram Mahmut , Mamut Mamatjan , Zhang Rui , Hamudun Arkin
Published: January 2011

Bone forming phenomenon is an exquisitely genetic programmed and dynamic process that occur from early embryo skeletal development to postnatal growth and culminating in the formation of highly variable and complex but perfect optimized structures. In this study the high resolution imaging techniques such as computerized tomography (CT) is used to obtain quantitative information about the progressive changes in three-dimensional (3D) skeletal morphology and density of rabbit thighbone during early embryo skeletal development to postnatal growth. Then the changes of the thighbone volume, shape and density during the bone growth process are evaluated by using the 3D images reconstruction method, and the growing direction of the thighbone structure is also evaluated. The effects of genetic and environmental complications to optimized skeletal patterns of bone are discussed.
The Strength Evaluation and Reliability Analysis of Periodic Symmetric Struts Support
Authors: Yang Jing Xiang , Zhang Ya Xin , Gheni Mamtimin , Chang Ping Ping , Chen Kai Yin , Yu Lie
Published: January 2011

In this paper, strength evaluations and reliability analysis are conducted for different types of PSSS(Periodically Symmetric Struts Supports) based on the FEA(Finite Element Analysis). The numerical models are established at first, and the PMA(Prestressed Modal Analysis) is conducted. The nodal stress value of all of the gauss points in elements are extracted out and the stress distributions are evaluated for each type of PSSS. Then using nonlinear least squares method, curve fitting is carried out, and the stress probability distribution function is obtained. The results show that although using different number of struts, the stress distribution function obeys the exponential distribution. By using nonlinear least squares method again for the distribution parameters a and b of different exponential functions, the relationship between number of struts and distribution function is obtained, and the mathematical models of the stress probability distribution functions for different supports are established. Finally, the new stress distribution model is introduced by considering the DSSI(Damaged Stress-Strength Interference), and the reliability evaluation for different types of periodically symmetric struts supports is carried out.
Capacity Analysis of Urban Highway Intersections
Authors: Tohti Gulbahar , Gheni Mamtimin , Chen Yu Feng , Tursun Mamatjan
Published: January 2011

In this paper, based on survey data of delays on intersections in urban highways and in accordance with theoretical capacity of each traffic lane, various reasons of delay in intersections are analyzed numerically. A discrete traffic model to simulate traffic in intersections using Gaussian mesh method is built. After modifying intersection properties, weight of each factor in terms of their effect to capacity is acquired. An optimized way to solve traffic delay is hereby recommended.
Failure Behaviour of Semantan Bamboo Strips Loaded in Bending and Shear
Authors: Bahari Shahril Anuar , Ahmad Mansur
Published: January 2011

In this study, the classification of modes of failure, the observation of microscopic failures and the mechanical properties of Semantan bamboo strips were investigated. Specimens were loaded in bending and shear parallel to grain. Specimens were taken from internodes and node parts in bottom, middle and top portions of bamboo culms. From the classification, different modes of failure occurred in different parts of Semantan bamboo culms loaded in bending and shear. From the microscopic observation, the failures occurred in both parenchyma and vascular bundles regions for all classified failure modes from all tests, except for Even Splitting Mode from shear. This mode exhibited failure in parenchyma only, without any failure in vascular bundles regions. The Maximum Stress (σml) values between failure modes for both tests were significantly different. Generally, anatomical behaviour at different culm’s parts had influenced the different modes of failure and microscopic failures of Semantan bamboo strips loaded in bending and shear.
Damage Assessment of a Structure by a Digital Image Correlation Method
Authors: Yokota Shin , Ohnuki Hirotaka , Machida Kenji , Zhang Zu Guang
Published: January 2011

Health assessment of a structure is various. In architecture and civil engineering, a natural frequency is calculated by conducting the frequency analysis of the response waveform of the structure. The natural frequency measurement has been performed with a speedometer, an acceleration sensor and a laser Doppler velocimeter, but possibility of the evaluation of the natural frequency by the digital image correlation method was examined mainly. In the case of the digital image correlation method, if a picture and time are connected, the displacement response of the structure is obtained. Hence, we considered the applicability of it to the vibration phenomenon. We carried out displacement comparison with the finite element method, and then investigated the accuracy of the displacement response waveform. Furthermore, it succeeded in assessment of the natural frequency by the frequency analysis. The health assessment of the structure is possible by using the digital image correlation method and frequency analysis.
The Study of Underfill Epoxy Hardness in Reducing Curing Process Time for Flip Chip Packaging
Authors: Kornain Zainudin , Jalar Azman , Rashid Rozaidi , Abdullah Shahrum
Published: January 2011

Underfilling is the vital process to reduce the impact of the thermal stress that results from the mismatch in the co-efficient of thermal expansion (CTE) between the silicon chip and the substrate in Flip Chip Packaging. This paper reported the pattern of underfill’s hardness during curing process for large die Ceramic Flip Chip Ball Grid Array (FC-CBGA). A commercial amine based underfill epoxy was dispensed into HiCTE FC-CBGA and cured in curing oven under a new method of two-step curing profile. Nano-identation test was employed to investigate the hardness of underfill epoxy during curing steps. The result has shown the almost similar hardness of fillet area and centre of the package after cured which presented uniformity of curing states. The total curing time/cycle in production was potentially reduced due to no significant different of hardness after 60 min and 120 min during the period of second hold temperature.
Experimental and Analytical Studies of Fatigue Crack Growth in Peened after Skimmed Friction Stir Welded Joint of 2024-T351 Al Alloy
Authors: Golestaneh Amirreza Fahim , Ali Aidy , Bayat Mehdi
Published: January 2011

The present work studies the crack behavior along the surface of the friction stir welded (FSW) joint of 2024-T351 aluminum alloy. The surface engineering of shot peening and skimming are used to enhance the fracture characteristics of the joint. Then multiple crack initiation is detected within FSW zones by scanning electron microscopy, while plastic replication technique is used to monitor the crack propagation. The variation of residual stress is measured (using hole drilling technique) as well as hardness characteristic (using standard method of Vicker) to study the fatigue life of the FSW by two models of Pearson and Nicholls, incorporating crack closure and stress relaxation.
Design Optimization of Bi-Tubular Thin Walled Columns for Crashworthiness Application
Authors: Tarlochan Faris
Published: January 2011

Improving crashworthiness of vehicles is considered to be one of the main concerns in traffic safety. The study focused on new designs that can be incorporated into existing vehicles. The paper presents a crashworthiness design of a bi-tubular thin walled column for different dimension profiles. To formulate the complex crashworthiness design problem, the response surface method (RSM) was utilized. The design of experiments of the factorial design is used to construct the response surface for the specific energy absorption (SEA). This surface was optimized for SEA. Results from a finite element analysis of elastic plastic square bi-tubular steel tubes subjected to dynamic axial impact load are reported. The bi-tubular design has shown good potential as an efficient energy absorber in comparison to existing conventional energy absorbing structures.
A Theoretical Study on the Influence of Frequency on the Dynamic Characteristics of Air Film
Authors: Qi She Miao , Ho Y.S. , Geng Hai Peng , Yu Lie
Published: January 2011

A general method is developed to deal with the compressibility of air film and to predict the linear dynamic stiffness and damping coefficients of air-lubricated bearings over the whole range of frequency. Numerical results reveal that both stiffness and damping coefficients are functions of not only the static parameters such as eccentricity and attitude angle, but also the frequency of disturbance. The coefficients are continuous and tend to certain values even when the frequency approaches zero or positive infinity. In general, the direct terms of the dynamic stiffness increase with the increase of the frequency, while the cross-coupling terms tend to an equal value when the frequency becomes infinite, and all the damping coefficients decrease in the higher frequency region and vanish when the frequency approaches positive infinity.
Vibrational Fatigue Analysis of a Strain Loading Using the Frequency and Wavelet Filtering Methods
Authors: Abdullah Shahrum , Teuku Edisah Putra , Mohd. Zaki Nuawi , Zulkifli Mohd. Nopiah
Published: January 2011

This paper presents a comparison work between the filtering methods of fatigue strain loadings using the frequency spectrum and the wavelet transform (WT), in which a raw loading signal can be simplified for purpose of simulation. For this reason, the Fast Fourier Transform (FFT) and the Morlet wavelet algorithms were used in order to transform the vibrational fatigue time series into the frequency domain signal, leading to the observation of the frequency characteristics of the signal. To retain high amplitude cycles in the FFT algorithm, a low pass filter technique was applied to remove the high frequency signals with small amplitude that are non-damaging. The departure of high frequency information smoothed the low amplitude cycles at high frequency events in the fatigue signal. The Butterworth filter was selected as the most efficient filter design as it retained most of the fatigue damage and also had the capability to remove 30 % of the original low amplitude cycles. On the other hand, the Morlet wavelet managed to remove 64 % of the original 59 second signal. This wavelet filtering method removed 34 % more than the similar procedure applied through the FFT approach. Hence, this fatigue data summarising algorithm can be used for studying the durability characteristics of automotive components.
Optimization of Cathodic Protection System Design for Pipe-Lines Structure with Ribbon Sacrificial Anode Using BEM and GA
Authors: Safuadi M. , Ridha M. , Huzni Syifaul , Fonna Syarizal , Ariffin Ahmad Kamal , Daud Abdul Razak
Published: January 2011

In this paper, combination of a boundary element formulation and genetic algorithm (GA) was developed and used for analyzing of cathodic protection systems of buried pipe-lines structures. It is very important to maintain the effectiveness of the cathodic protection system for pipeline structure, in order to lengthen the lifetime of the system. However, nowadays the evaluation of the effectiveness of the system only could be performed after the system applying in the field. This study was conducted to combine 2D boundary element method (BEM) and GA in order to evaluate the effectiveness of the cathodic protection system for pipe-lines structure using ribbon sacrificial anode. Two factors i.e. the soil conductivity and the distance between pipe-lines and anode, were analyzed by using the proposed method. In this method, the potential in the domain was modeled by Laplace’s equation. The anode and cathode areas were represented by polarization curves of different metals. Boundary element method was applied to solve the Laplace’s equation to obtain any potential and current density in the whole surface of the pipe. The pipe and anode were modeled into 2D model. The numerical analysis result shows that the optimum distance between pipe-lines and anode can be determined by combining BEM and GA.
Perforated Plate Backing with Coconut Fiber as Sound Absorber for Low and Mid Range Frequencies
Authors: R. Zulkifli , Zulkarnain  , Nor Mohd Jailani Mohd , Abdullah Shahrum
Published: January 2011

A material’s sound absorbing properties can be described as a sound absorption coefficient in a particular frequency range. Porous absorbers are the most commonly used sound absorbing materials, however they do not have good absorption properties at low and mid frequencies. In order to increase the absorption properties at low and mid frequencies, porous absorber should have larger thickness and size. By using perforated plates backing with porous absorber, it is possible to gain higher noise absorption at low and mid frequencies. This study was conducted to investigate the effect of perforation size ratio, mass, air gap and holes diameter of perforated plates as backing plate for porous absorber. Coconut fibres were used as backing medium for perforated plates. Perforated plates were fabricated using two different materials; aluminium and zinc plates with perforation size ratio of 0.10, 0.15 and 0.22 at thickness of 1 mm. The holes diameters of the perforated plates are 2 mm, 3 mm, and 4 mm, respectively. The tests samples were tested at the acoustic lab of the Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia according to ASTM E 1050-98 international standards for noise absorption coefficient. The data presented the perforated plates backing with coconut fibers have perforation ratio less to 0.22 showed the significant absorption at 800 Hz – 1800 Hz frequency range. The perforated plates backing with coconut fibers that their holes diameters are 4 mm also showed a good absorption at 600 Hz – 1800 Hz frequency range. However, perforated plates backing with coconut fibers showed a decreasing absorption coefficient at frequencies more than 1800 Hz.
Asymptotic Analysis for the Singular Stress Behaviour around an Interface Edge of Dissimilar Power-Law Hardening Materials Joint
Authors: Kowser Md. Arefin , Arai Yoshio , Araki Wakako
Published: January 2011

An asymptotic analysis for singular stress fields around an interface-edge of dissimilar power-law hardening materials joint has been presented under plane strain condition and J2 deformation plasticity theory. Both the balance of force and the continuity of displacement are satisfied on the interface. In the higher order approximation, the nonlinear effective stress term was expanded by Taylor series. An iteration method is proposed for the determination of singular fields around interface edge. Multiple stress singular terms exist for in the higher order approximation. The order of stress singularity has a dependency with the combination of hardening exponents, .
Simulation of Compression and Spring-Back Phenomena of Sandwich Structure with Honeycomb Core Subjected to Low Energy and Low Velocity Impact
Authors: Aminanda Yulfian , Sutjipto Agus Geter Edy , Adesta Erry Yulian Triblas , Castanie Bruno
Published: January 2011

The paper proposes first to study the behavior of honeycomb alone under uniform cyclic compression-relaxation loading. It is found that the behavior is linear until it reaches the maximum force following by a sudden drop of force and at the end following by a constant force during the compression. This force-displacement behavior is observed to be similar for all material of honeycomb such as; Nomex (with different densities and cell dimensions), fiber-glass and aluminum. From experimental study, the behavior becomes significantly non-linear in the area of constant force (flat zone) especially the spring-back behavior. A mathematical model is proposed to simulate completely compression-spring-back behavior of honeycomb. This mathematical model describes the behavior of honeycomb in compression and spring-back loading only in function of the maximum depth due to impact. The proposed mathematical model is then integrated to FEA model to simulate the spring-back behavior of sandwich structure with metallic skins and honeycomb core. After integrating the influence of skin-honeycomb interaction, a complete mathematical model which includes non-linearity of compression-spring-back behavior and rotation due to skin-honeycomb interaction is proposed to simulate the behavior of sandwich structure subjected to low energy/ low velocity impact (indentation) loading using spherical impactor. Some simulations of indentation and relaxation on sandwich structure with nomex honeycomb using different diameters of spherical indenter and different thickness of metallic skin are obtained with a good comparison with experimental results.
Analysis of an Instrumented Charpy Impact Using Power Spectrum Density
Authors: Ali Mohd Basri , Abdullah Shahrum , Nuawi Mohd Zaki , Ariffin Ahmad Kamal
Published: January 2011

Dynamic fracture properties of most engineering materials are evaluated using Charpy test. The dynamic responses of the standard Charpy impact machine are experimentally studied using the relevant data acquisition system in order to obtain the impact response. For this reason, strain gauges were connected to the data acquisition set and it was then attached to the striker for the signal collection. The numerical analysis by mean of the finite element method has been used to obtain the findings. The standard Charpy modelling using the aluminium 6061 material was used in order to obtain strain responses on the striker during the impact simulation. A standard Charpy specimen aluminium 6061 was used for the experimental impact testing. A power spectrum density (PSD) approach is then used to convert a signal from the time domain to the frequency domain using the fast Fourier transform (FFT) method. Related parameters on strain signals, power spectrum density (PSD), comparison between experiment and finite element analysis, and the relationship between all the parameters were finally correlated and discussed. It was found that the finite element results are validated to show simulated time histories and its PSD compared with experimental work.
Cracking Safety Evaluation of Massive Concrete Structures
Authors: Abdulrazeg A.A. , Khanazaei Parvin , Noorzaei Jamal , Jaafar M.S. , Mohammed T.A. , Thanoon W.A.
Published: January 2011

High temperatures generated in the concrete due to the hydration of cement induce thermal tensile stresses. If these stresses are not controlled, they cause cracks in mass concrete structures such as dams. Hence, the thermal and structural stresses needs to be checked against the possibility of cracking to evaluate the safety of the dam. This study deals with formulation and simplified procedure to predict the possibility of crack development in RCC dam. An existing 2-D code has been modified by implementing the crack prediction procedures. The applicability of the modified 2-D code has been shown by analyzing a real RCC dam called Zirdan dam situated in southeast of Iran. The predicted stresses which were obtained through the finite element analysis are examined against the crack development at Gaussian points and it was found that the dam is structurally safe.
Damage Mechanics Model for Solder/Intermetallics Interface Fracture Process in Solder Joints
Authors: Shaffiar N.M. , Lai Z.B. , Tamin Mohd Nasir
Published: January 2011

The relatively brittle solder/IMC interface fracture process in reflowed solder joints is examined using finite element (FE) method. The interface decohesion is described using a traction-separation quadratic failure criterion along with a mixed-mode displacement formulation for the interface fracture event. Reflowed Sn-4Ag-0.5Cu (SAC405) solder ball on OSP copper pad and orthotropic FR4 substrate under ball shear push test condition at 3000 mm/sec is simulated. Unified inelastic strain constitutive model describes the strain rate-response of the SAC405 solder. Comparable simulated and measured load-displacement values during solder ball shear push test serve as validation of the damage-based FE model. Results indicate a nonlinear damage evolution at each material point of the solder/IMC interface during the ball shear push test. The normal-to-shear traction ratio at the onset of the interface fracture is 1.59 indicating significant induced bending effect due to shear tool clearance. Rapid interface crack propagation is predicted following crack initiation event with the average crack speed up to 24.6 times the applied shear tool speed. The high stress concentration along the edge of the solder/IMC interface facilitates local crack initiation and dictates the shape of the predicted dynamic crack front.
Effects of Locations of Adhesive Hollows on Interfacial Stress
Authors: Xie Zhi Hong , Huang Pei Yan , Zhong Gen Quan , Deng Jun
Published: January 2011

Fiber Reinforced Polymer (FRP) has been effectively used for strengthening concrete beams. In this study, nonlinear finite element (FE) model of the beam strengthened with CFRP is established to analyze the debonding failure caused by the adhesive hollow defects. The constitutive relationship of the adhesive layer in the FE models is similar to Monti’s bi-linear mode. Three different locations of the hollows are considered in the FE models. The principal stresses in the concrete, the debonding stresses in the adhesive and the stress in CFRP are calculated. The results show that the effect of the locations of the hollow is marginal on the principal stresses in the concrete. When the hollow appears close to the interfacial end, the debonding stresses in the adhesive and the shear stress in the CFRP are significant, which easily causes the debonding failure.
Analysis of Concrete Early-Age Shrinkage Based on the Theory of Humidity Diffusion
Authors: Li Yun Feng , Du Rong Qiang , Kong Fan Ying
Published: January 2011

The early-age shrinkage cracking of concrete plays an important role to the accelerated deterioration and shortening the service life of concrete structures. Modern concretes are more sensitive to cracking immediately after setting, which is due to material characteristics (lower water/binder ratio and higher cement content) and external environmental fluctuations (humidity and temperature change). Determination of concrete free shrinkage is the basis of shrinkage cracking research. Analytical models of the autogenous shrinkage and drying shrinkage are established in this paper. The calculated results agree well with the experimental results.
Stress Distribution Analysis on Four Types of Stress Corrosion Cracking Specimen
Authors: Huzni Syifaul , Ridha M. , Ariffin Ahmad Kamal
Published: January 2011

Stress distribution analysis on four types of stress corrosion cracking (SCC) specimen is presented in this paper. This work was performed using commercial finite element based software, ANSYS. Two types of mesh arrangements, fixed mesh with different mesh size and adaptive mesh, were employed in this work to study the effect of mesh size on stress distribution of SCC specimen. Four types of SCC specimen were studied in this work, i.e. C-ring specimen, tensile test specimen, pre-crack cantilever beam specimen and U-bend specimen. Simulation result shows that stress distribution on the SCC specimen much affected by mesh size and arrangement, especially for specimen with notch. By performing the stress analysis, less effort needed in order to determine the location of corrosion potential measurement on the SCC specimen. This will be very helpful for future work of SCC study.
Elastic-Plastic Flange Wrinkling of Circular Plates in Deep Drawing Process
Authors: Moayyedian Farzad , Kadkhodayan Mehran
Published: January 2011

This paper deals with two-dimensional plane stress wrinkling model of elastic/plastic annular plate. Based on energy method and nonlinearity of strain-displacement law, a bifurcation functional in polar coordinate is derived analytically. This technique leads to the critical conditions for the onset of the elastic/plastic wrinkling of the flange during the deep-drawing process. Tresca yield criterion along with deformation theory of plasticity are utilized and the material of the plate is assumed to behave perfectly plastic. Moreover, the influence of the blankholder upon wrinkling and on the number of the generated waves is quantitatively predicted by the suggested scheme. The main advantage of the proposed solution is its better agreement with the experimental and analytical results found by the other resarchers.
Analysis of Mechanical Performance of Crumb Rubber Concrete by Different Aggregate Shape under Uniaxial Compression on Mesoscopic
Authors: Zhong Gen Quan , Guo Yong Chang , Li Li Juan , Liu Feng
Published: January 2011

From micro perspective, crumb rubber concrete (CRC) is viewed as a composite consisting of mortar matrix, aggregates and rubber particle. In this paper, based on random aggregate model with different aggregate shape in planar, the mechanical properties of CRC using linear Mohr-coulomb constitutive relation are studied by nonlinear finite element method under uniaxial compression on mesoscopic. The number of random aggregates is calculated in two-dimension by Walraven formula. Circular random aggregate model, elliptic random aggregate model and polygonal random aggregate model are established. Stress-strain curves under varieties of conditions are derived and compared with the test results. The results show that the simulative stress-strain curve fit the reality very much. In the numerical analysis, the aggregate shape has little effect on the mechanical properties of CRC.
Fracture and Plasticity in Nano-Porous Particle-Polymer Composites
Authors: Alam Parvez , Toivakka Martti
Published: January 2011

A fracture mechanics algorithm, used for continuum mechanics simulations of nano-porous particle-polymer composites, is described herein. The model comprises close to a thousand ceramic particles bound together by latex polymer. These packings are generated using probabilistic methods (Monte Carlo). Pore-space arises as a function of particle shape and position coupled to the concentration and distribution of latex. Since the bridges are the weakest links in the solid state continuum, an understanding of failure behaviour is paramount for the design and optimisation of these composites. The objective of this research is to statistically characterise adhesive failure at particle-latex interfaces against cohesive failure within the latex bridges. To achieve this, a novel numerical method was developed. This method solves ordinary differential equations for vectors of force and displacement in layers through the computational packing. The model includes a scheme for non-linear elastic behaviour that evolves into a plastic flow regime. The model moreover incorporates a routine for interfacial failure between particulates and binder. Geometrical features such as solid state anfractuosity, bridge orientation, material fraction and coordination numbers are calculated from the packing output. The number of bridges straining plastically within the packing is lower than those that fracture at the interface. Fracture and failure are both related to the particle-binder coordination number. There is no evidence to suggest that decreasing the contacting sizes of binder at interfaces as well as making them thinner will lead to more plastic failure and decrease fracture. Rather, both plastic failure and fracture increase as a function of decreased contacting sizes and bulk diameters. The residual elastic modulus decreases exponentially as the number of broken connections increases.
Effect of Beam Height on Elastic Impact Load Subjected to Transverse Impact of Bar
Authors: Ju Jin San , Ding Min , Shi Xu Dong , Cen Song , Jiang Xiu Gen , Chen Xing Hua
Published: January 2011

The procedure of beam subjected to transverse impact by bar is simulated using numerical method. The method considers the propagation of the expansion wave and shear wave in beam. The effect of beam height on elastic impact loads with different bar lengths and beam heights are investigated. With condition that the length of beam is longer than or equal to that of bar, the numerical solution shows that: when the bar length is constant, if the length of bar is shorter than the height of beam, the longer the bar, the bigger the peak value of impact force; the impact load curve consists of ascending and descending part basically; When the bar length is longer than or equal to beam height, the peak value of impact force is not related to the bar length and equal to that of bar with the same length as the beam height; the impact load curve is trapezium. The contact time is proportional to bar length and equal to the duration time of stress wave propagation in the bar for once return. If the bar length is constant, when bar length is shorter than beam height, the impact load is not related to beam height; when bar length longer than or equal to beam height, the peak value of impact force increases along with the beam height and approach to that of bar with the same length as the beam height.
Out-of-Plane Secondary Bifurcation Buckling Behavior of Elastic Circle Pipe Arch
Authors: He Yu Zhi , Liu Chang Yun , Hou Zhen Hua , Zhang Guang Kui , Chen Xing Hua , Lin Zi Chen , Ju Jin San
Published: January 2011

The out-of-plane secondary bifurcation buckling load-displacement equilibrium paths of the elastic circle pipe arch with and without out-of-plane brace at the top of the arch are traced using a new numerical tracing strategy. The out-of-plane secondary bifurcation buckling loads of the arch with the same sections and different rise-span ratios are obtained under the concentrated load at the top of the arch and the full span uniformly distributed load, which are compared with out-of-plane linear buckling load and in-plane primary buckling load. The calculation results show: for the same section circle pipe arches without the out-of-plane brace and under the concentrated load at the top the arch, the out-of-plane secondary buckling load is always less than the in-plane primary buckling load and the out-of-plane buckling will occur before the in-plane primary buckling. The out-of-plane secondary bifurcation buckling load of the arch with 0.2 rise-span ratio is the biggest. The bigger the rise-span ratio is, the bigger the difference between out-of-plane and in-plane buckling load. When the arch is subjected to full span uniformly distributed load, the out-of-plane buckling will also occur before the in-plane primary buckling and the out-of-plane secondary bifurcation buckling load of the arch with 0.4 rise-span ratio is the biggest. The difference between out-of-plane and in-plane buckling load of the arch with 0.2 rise-span ratio is the biggest. For the circle pipe arch with the out-of-plane brace at the top of the arch, the out-of-plane buckling load of the arch with 0.4 rise-span ratio is the biggest under the two load conditions. The brace can raise the out-of-plane buckling load significantly especially for the arch with big rise-span ratio and under full span load. The out-of-plane buckling will occur before the in-plane primary buckling when the arch is under full span uniformly distributed load. The out-of-plane buckling will occur before the in-plane primary buckling only when the arch is under concentrated load and the rise-span ratio of the arch is less than 0.3. No matter there is or not brace for the arch, the ultimate load carry capacity of the arches increase a little bit after the out-of-plane secondary buckling occurs.
Finite Element Analysis of 4-Step 3-Dimensional Braided Composite Structure under High Velocity Impact
Authors: Zheng Xi Tao , Yang Qiang , Gou Lin Hu
Published: January 2011

The finite element method was used to simulate and analyze I-shaped beam which was made of the three-dimensional braided composite and suffered from bird impact. The models contained five braiding modes, two kinds of three-dimensional three-directional braiding and three kinds of three-dimensional six-directional braiding. Three kinds of thickness (10 mm, 15 mm and 20 mm), and all of these models were impacted by three different velocities (80 m/s, 150 m/s and 200 m/s) respectively. The bird has different mechanical properties in different velocities; therefore, different finite element models were used. Also, the stiffness of the braided composites degraded while damaged was absolutely considered. The numerical results indicated that, the capability of anti-bird impact was best when the beam was made of three-dimensional six-directional braided composites with sizes proportion of braiding yarn 1:1:1 for the four-directional, five-directional and six-directional. After analysis, the most reasonable braiding mode and structure dimension was obtained, in which condition the I-shaped beam was strong enough to resist bird impact and less weight.
Characterisations of Cu-Based Coated Al7075 via Plasma-Spray Technique
Authors: Ghazali Mariyam Jameelah , Kamal S.E. Mat , Abdullah Shahrum
Published: January 2011

This work aims to characterise a Cu-based coating material on Al-7075 by using a plasma-spray technique in order to enhance the surface properties of components for automotive applications. Plasma-spray is a process for formation coating on substrates whereby a feedstock is rapidly heated to a molten or near-molten state, and a gas are use to propel the material toward suitably prepared substrate. The most prominent advantages of this method are virtually any coating material can be used and any substrate material can be coated with low thermal stress on substrate parts and high deposition rates [1]. The coating characteristic can be controlled by varying the process variables such as input powers, material feed rates, gas pressures, surface preparation of the substrate and spray distance [2]. The effect of crucial parameters like the electric power input to plasma, spray rate and substrate roughness were studied. The experiments of spraying were design using a 23 fractional factorial plan. The plan allows studying the effect of each factor on the response variables, as well as the effect of interactions between factors on the response variable at the least number of experiment runs. The coating layers have been characterised with respect to the structure by using a scanning electron microscopy (SEM). The result indicates that sprayed particles cool and built up into pancake-like shapes splat, characteristic a plasma spray electric process products. It was found that the optimum parameters were obtained at a power of 24.6 kW, with a powder feed rate of 1 rpm and substrate roughness of 0.5µm.
A New Realization on Electro-Elastic Love Waves In Piezoelectric Layered Solids
Authors: Qian Zheng Hua , Jin Feng , Hirose Sohichi
Published: January 2011

In this paper, we study the propagation of electro-elastic Love waves in a piezoelectric layered solid consisting of a transversely isotropic piezoelectric ceramic film deposited on an isotropic metal substrate. Dispersion relations are obtained in a very concise mathematical form for both electrically open and shorted circuits. Numerical example is given for a PZT-4/steel system. An interesting phenomenon on the fundamental mode of the Love waves in the case of electrically shorted circuit is realized and validated through the discussion on the limit values of phase velocity using the obtained dispersion relations. This validation appears new and is significant to understand the Love wave modes themselves and to the design of acoustic wave devices.
The Development of Validation Technique in Variable Amplitude Loadings Strain Repetitive Data Collection
Authors: Baharin M.N. , Mohd Nopiah Zulkifli , Abdullah Shahrum , Khairir Muhammad Ihsan , Lennie Abdul
Published: January 2011

In any experiment, there is a need to verify the reliability of the collected data. One of the solutions is to measure the data repetitively. It will lead to measurement of inconsistency that exists in the data. Similar things also happen in variable amplitude (VA) loading strain data collection where the data also need to be measured repetitively in order the collected data is reliable. The main objective of this study is to validate the reliability of collected VA loading strain data. Two techniques will be used for identifying the similarity in the pattern for strain signal which was measured repetitively. The probability distribution function (PDF) and power spectral density (PSD) diagrams of the strain data were used as the main tool to construct profile plots for the case study data. Then, each profile plot will be compared to each other in order to identify any similarities that exist in the case study data. For the purpose of the study, a set of nonstationary VA loadings strain data that exhibits random behaviour was used. This random data was measured in the unit of microstrain on the lower suspension arm of a car. The data was repetitively measured for 60 seconds at the sampling rate of 500Hz, giving 30,000 discrete data points. The distribution of the collected data was analysed using the PDF and PSD. Based on the analysis, it was found that PSD can produce better results at identifying the similar features that exist in the profile plot compared to PDF.
Micro-Hardness and Residual Stress Relaxation of 2024 T351 Aluminum Alloy
Authors: Zaroog Omar Suliman , Ali Aidy , Barkawi Sahari B. , Zahari Rizal
Published: January 2011

The residual stress relaxation can be divided into two stages: The first cycle relaxation and the following cycles. In both stages, residual stress relaxed considerably from the initial state. The aim of this study is to investigate the residual stress relaxation and microhardness reduction after first and second cyclic load. A 2024 T351 aluminum alloy specimens were shot peened into three shot peening intensities. The fatigue test for first and second cyclic loads of two loads 15.5 kN and 30 kN was performed. The initial residual stress and residual stress after the first and second cycle stress was measured for the three shot peening intensities using X-ray diffraction. Microhardness test was performed for each specimen. The results showed that the residual stress relaxation for first cycle was reached more than 40% of the initial residual stress and it depends on the load amplitude, and microhardness decreased for the first cycle reached 22% and also it depended on load amplitude.
Effect of Aqueous Environment on High Cycle and Very-High-Cycle Fatigue Behavior for a Structural Steel
Authors: Hong You Shi , Qian Gui An
Published: January 2011

In this paper, rotary bending fatigue tests for a structural steel were performed in laboratory air, fresh water and 3.5% NaCl aqueous solution, respectively, thus to investigate the influence of environmental media on the fatigue propensity of the steel, especially in high cycle and very-high-cycle fatigue regimes. The results show that the fatigue strength of the steel in water is remarkably degraded compared with the case tested in air, and that the fatigue strength in 3.5% NaCl solution is even lower than that tested in water. The fracture surfaces were examined to reveal fatigue crack initiation and propagation characteristics in air and aqueous environments.
Estimation of Elastic Follow-Up in Structures
Authors: Hadidi-Moud Saeid , Smith David John
Published: January 2011

Using simplified benchmark models, representative of the behavior of real structures, a unified framework for quantification of elastic follow-up (EFU) in structures has been provided. Closed form analytical solutions for evaluation of elastic follow-up are presented for model structures. The impact of elastic follow-up on the relaxation i.e. the redistribution of residual stresses has been explored and hence its significance in the integrity assessment of structures in general and in classification of residual stresses in particular has been highlighted.
Thermal Cycling Induced Crack Nucleation and Propagation in Thermal Barrier Coating System
Authors: Sun Yong Le , Zhang Wei Xu , Tian Man , Wang Tie Jun
Published: January 2011

Failure of thermal barrier coating (TBC) system is associated with the morphological imperfection of thermally grown oxide (TGO) layer. The objective of this work is to numerically investigate the crack nucleation and propagation in TBC system upon thermal cycling based on a cohesive zone model, in which TGO thickness imperfection effect is incorporated. The results show that TGO/BC (bond coat) interface is subjected to high tensile stress in the vicinity of TGO thickness imperfection during thermal cycling, thereby inducing crack nucleation. Owing to the plastic deformation of BC, fracture behavior of TGO/BC interface is related to BC yield strength for a typical thermal growth rate of TGO. Furthermore, the embedded oxide in BC could be also ruptured as a result of the increasing transverse stress, which will lead to the coalescence of adjacent cracks.