bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanical Properties and Damage Mechanism of Glass Fiber Composite Laminates in Compression
Authors: Zhang Xue Yi , Zou Guang Ping , Yang Li Hong
Published: October 2009

Application of composite laminates was very wide in aerospace engineering, civil engineering, wind energy, auto industry, etc. Low cost glass fiber textile was often applied into composite laminates by many composites companies. It is of import that investigation of mechanical properties and damage mechanism of this composites laminates. Two types of composite laminates were studied in this paper. One type of composite laminates was made of glass fiber biaxial cloth. The other was made of glass fiber composite felt. Each type composite laminates has different direction aligned. Many specimen were tested in compression with universal testing materials machine model INSTRON 5500R. Strength of composite laminates and stress-strain diagram was obtained in these experiments. Effect of fiber different orientation on compression strength of laminates was found. Shear stresses between two laminas were calculated. Fracture mechanism of composites laminates was analyzed by macro-method. Fractography of laminates was applied into analysis of mechanism. SEM photo was acquired and observed in detail. The result is that strength and failure mechanism of different types composite laminates varied with fiber orientation and different textiles.
Experimental Investigation of Large Deformation Fracture for Rubber Materials
Authors: Kang Yi Lan , Xiao X. , Li Xiao Lei , Tan Xiao Hua
Published: October 2009

With the increasing investigation on reliability and stability of engineering structures, it becomes important for reseach on mechanical properties of materials under fracutre conditions. Concerning to fracture problems of large deformation materials, deformation characteristics of the crack tip field is necessarily needed. This paper presents an experimental analysis on a double-cracked rubber disk under the I-II mixed-mode fracture condition. Deformation properties around the crack tip are described through analyzing displacement information acquired by digital moiré method of circular and radial gratings. Also the existence of sector division mode under mixed loading condition is verified, and it is also found experimentally that the shear component makes the sectors shift.
Transient Heat Transfer Analysis for Brake Disks Using SPH
Authors: Rong Gui Ming , Kisu Hiroyuki
Published: October 2009

Smoothed particle hydrodynamics (SPH) is a mesh-free numerical approximation technique
for simulating various physical problems. A calculation system for transient heat transfer problem by
SPH has been improved to deal with various boundary conditions and several model calculations
are performed to verify it. As a practical application, the transient temperature field of a brake disk
under emergency braking is analyzed. Both solid and ventilated disks are modeled with a moving
heat source on the sliding surface. The numerical results show that the temperature sharply fluctuates
because of the cyclic loading. Improvement of the calculation model is also discussed.
Strength and Ductility of Reactive Powder Concrete Columns
Authors: Zhao Guan Yuan , Hao Wen Xiu
Published: October 2009

Two hollow rectangular bridge columns with Reactive powder concrete (RPC) were tested under a cyclically reversed horizontal load. Based on the test results, the seismic behavior of such columns was presented. An analytical model was developed to predict the force-displacement relationship of specimens. The test results were also compared to the proposed analytical model. It was found that the ductility factors of the specimens are over 4.0, and the proposed analytical model can predict the force-displacement relationship of such columns with acceptable accuracy.
Computational Fracture Analyses of a Compact Tension Shear (CTS) Specimen with an Inclined Crack Front
Authors: Qi Gui Ying , Buchholz Friedrich G. , Yan Sheng Yuan , Li Qing Fen
Published: October 2009

In this paper some results of 3D-finite element analyses of a modified CTS-specimen(MCTS) with an inclined crack front are presented. It will be shown, that through the inclination of the crack front, even under pure in-plane shear loading of the specimen, mixed-mode II and III loading conditions can be generated along the straight inclined crack front. Furthermore a superposition of all fracture modes I, II and III can be generated, if this MCTS-specimen is subject to an in-plane tension/shear loading. The computational fracture analysis is based on the calculation of separated energy release rates GI, GII and GIII along the crack front by the numerically highly effective modified virtual crack closure integral(MVCCI)-method and for the finite element(FE)-modelling the commercially available FE-code ANSYS is utilized.
Study on Initial Damage of Concrete
Authors: Wang Xiang Dong , Zhu Wei Xuan , Deng Ai Min , Qiu Ling , Wang Yue Feng
Published: October 2009

Many damage models of concrete have been put forward till now, of which some models are applied in engineering practices. The damage parameters play an important role in the calculations of damage with these models, which is determined during experiments. However, the tests of damage on concrete are rarely made, especially about the measuring method of initial damage. The initial damage is an essential parameter to study on the damage of concrete. Being based on the theory of damage, this paper analyze of the damaged and undamaged elastic modulus of concrete. The new method of determining undamaged elastic modulus from test results has been put forward, and then the initial damage has been quantified.
Numerical Simulation of a Stretch Bending Process
Authors: Lamanna Giuseppe , Caputo Francesco , Grassia Luigi , D'Amore Alberto , Soprano Alessandro
Published: October 2009

There are several difficulties associated with the numerical simulation of the stretch bending process of extruded components; the main ones are non-linear material behavior, geometrical non-linearities, modeling of boundary conditions, contact between die and specimen, springback during the unloading phase. Another very complex aspect is the calibration of the numerical model, as rather few experimental results are generally available. This paper deals with a numerical simulation of a complete stretch bending process with the aim to select the most suitable numerical procedure oriented to the evaluation of the process-induced distortions and residual stresses; to validate the proposed procedure, numerical–experimental comparisons have been performed. The activities reported have been developed in collaboration with ALENIA Finmeccanica s.p.a. within the VI FP’s research project called COMPACT.
Quantitative Nondestructive Evaluation of the Aluminum Alloy Using the Sheet Type Induced Current and the Single Sensor Scanning
Authors: Jun Jong Woo , Lee Jin Yi , Shin Ki Su , Hong Jung Ho
Published: October 2009

Single sensor scanning (hereafter SSS) used to inspect cracks on paramagnetic materials can measure the distribution of the root mean squared value (RMS) of the magnetic field around crack tips quantitatively when sheet type current is induced on the specimen. The vertical direction magnetic field alternates to the surface of the crack tips because the sheet type induced current on the specimen is distorted by the existence of the crack in an SSS system. The RMS distribution of the magnetic field, which can be measured by using SSS, depends on the crack size and shape, so it can be used to evaluate a crack size quantitatively. An algorithm of quantitative nondestructive testing and evaluation of cracks of various shapes and sizes on the aluminum alloy, Al7075 is proposed in this paper.
Damage Evaluation of Wheel Tread based on Contact Position between Wheel and Rail
Authors: Kwon Seok Jin , Lee Dong Hyung , Seo Jung Won , Ham Young Sam
Published: October 2009

The defect initiation and crack propagation in wheel may result in the damage of the railway vehicle or derailment. Therefore, it is important to evaluate the characteristics of the wheel tread. In the present paper, the characteristics of wheel tread based on contact positions, running distance and brake pattern are evaluated. To evaluate the damage for railway wheels, the measurement for the replication of wheel surface is carried out. The result shows that the damaged wheel tread is remarkably depended on the contact positions between wheel and rail. It should be noted that the replication test can be applied in new evaluation method of wheel damage.
Comparison of Tensile Strengths with Different Test Methods in Ultra High Strength Steel-Fiber Reinforced Concrete (UHS-SFRC)
Authors: Kang Su Tae , Park Jung Jun , Ryu Gum Sung , Koh Gyung Taek , Kim Sung Wook
Published: October 2009

Ultra High Strength Steel-Fiber Reinforced Concrete (UHS-SFRC) is characterized by very high compressive and tensile strength that is about 8 times of ordinary concrete, and high ductility owing to the addition of steel fibers. This paper investigates the relationship existing among the direct tensile strength, flexural tensile strength and splitting tensile strength of UHS-SFRC. Differently from ordinary concrete, it is found that the first cracking strengths in UHS-SFRC obtained through direct tensile test and splitting tensile test are similar, while the strength obtained from flexural tensile test is significantly larger than those from other tests. Based on the experimental results, relationships between the direct tensile strength and flexural tensile strength, between the first cracking strengths in direct tensile test and in flexural tensile test, and between the first cracking strength in direct tensile test and the flexural tensile strength are proposed.
Effect of Micaceous Iron Oxide Epoxy Coating on the MIC Behavior of Low Alloy Steel
Authors: Wang Jun , Li Qing Fen , Fu Yu Dong
Published: October 2009

Effect of micaceous iron oxide epoxy coating on the microbiological influenced corrosion (MIC) behavior of the low alloy steel was studied. Samples uncoated or coated with micaceous iron oxide epoxy coating in sterile seawater and SRB solution was investigated by using electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and so on. A series of data was obtained. Results show that micaceous iron oxide epoxy coating protected the base material effectively duo to its excellent physical barrier property.
An Efficient Way to Characterize the Fatigue Crack Growth Based on Numerical Analysis
Authors: Li Ya Zhi , He Jing , Zhang Zi Peng
Published: October 2009

The behavior of plasticity induced fatigue crack closure (PICC) in middle tension specimen was analyzed by the elastic-plastic finite element method. For the constant-K (CK) loading cases, the opening stress intensity factor are independent of crack length. The level of increases with the maximal applied stress intensity factor for given load ratio and increases with for fixed . The in plane strain state is much smaller than that in plane stress state. The results under CK loadings can be deduced to constant amplitude cyclic loading case during which the load ratio, maximal load level, crack length and specimen thickness are all the factors affecting the crack closure effect. The phenomena revealed in the analysis are beneficial in understanding the driving force mechanism of the fatigue crack growth.
Crack Propagating and Stress-Promoted the Precipitate of Ni3Ti in NiTi Thin Films
Authors: Li Yong Hua , Meng F.L. , Zheng Wei Tao , Wang Y.M.
Published: October 2009

This study investigated the stress-induced crack propagation and precipitation in Ti-51.45at.%Ni thin films. Tensile tests were carried out on CSS-44100 electron universal testing machine. The strain rate was 1.1×10-4 s-1. The surface micrographs of the NiTi thin film were obtained using scanning electron microscopy (SEM). The precipitates were determined by X-ray diffraction (XRD) experiments (D8 GADDS). The results showed that a series of parallel cracks grew in the film and the cracks were equally spaced. The fracture toughness of the film was estimated, =0.96MPa∙m1/2. The minimum crack spacing was about . The stress-strain curve can be divided into two stages. The first linear stage corresponded to the elastic deformation of the parent phase. In the following stage, the serrations were considered to be the stress relaxation due to the cracks propagating and the precipitate grain transformation. During tension the (102) peak intensity of Ni3Ti phase increased with elongation increased. The precipitate orientation was same.
Study on Stress and Strain Field of Mode II Quasi-Static Growing Crack in Pressure-Sensitive Dilatant Material
Authors: Yang Yong , Li Ning , Tang Li Qiang
Published: October 2009

A mechanical model of the pressure-sensitive dilatant material is established in order to investigate the viscous effect in quasi-static growing crack-tip field. The constitutive equations on the pressure-sensitive dilatant material are deducted. Through asymptotic analysis, it is shown that in the stable creep growing stage, the elastic-deformation and the visco-deformation are equally dominant in the near-tip field, as . The asymptotic solutions of separative variable in the crack-tip field of plane stress mode II quasi-static are aslo obtained. According to numerical calculation, the curves of stress, strain and displacement in terms of various parameters are given. The asymptotic solutions of quasi-static growing crack-tip field gained here can conveniently degenerate the incompressible case, when the Poisson ratio , named as HR field. The conclusions can provide the references for further studying the dynamic growing crack-tip field in the pressure-sensitive dilatant material.
Fracture Properties of PCBN as a Function of Loading Rate
Authors: Carolan Declan , Petrović M. , Ivanković Alojz , Murphy Neal
Published: October 2009

Polycrystalline Cubic Boron Nitride (PCBN) is a superhard material
which is used in machining of hardened steels and other abrasive and
aerospace grade alloys. In these applications the tools are subjected to high
operating temperatures, abrasive and impact loading. Impact loading can lead
to the sudden fracture and hence failure of the tool. In this work the static and
dynamic fracture toughness of PCBN is determined via a combined
experimental-numerical approach. The results show that the fracture toughness
of PCBN varies with loading rate.
Concrete Shrinkage-Induced Damage Taking into Account Aggregate Restraint
Authors: Guo Zhan Qi , Wang Gui Ming , Stroeven Piet , Shui Zhong He
Published: October 2009

The influence of concrete meso-structure and coarse aggregate size on early age crack is studied. In this study, concrete is regarded as a three-phase material based on shrinkage property. The mortar matrix and interfacial transition zones undergo shrinkage and no spherical coarse aggregate particles are considered to restain the shrinkage by particle interaction. The results show that concrete meso-structure plays an important role in the safety of concrete, different aggregate distribution in concrete leads to different initial cracks and propagation due to shrinkage. With the increase of maximum aggregate size, the value of shrinkage deformation becomes unstable and varies in a wide range; relevant shrinkage cracking becomes easier too.
Fracture Analysis for a 2D Prototype of Recycled Aggregate Concrete Using Discrete Cracking Model
Authors: Xiao Jian Zhuang , Wu Yu Ching , Zhang Sheng Dong
Published: October 2009

Fracture analysis has been made for a 2 dimensional prototype of recycled aggregate concrete using the discrete cracking model. The discrete element method has been developed based on quasi-brittle constitutive law to simulate the behavior of the 2 dimensional recycled aggregate concrete prototype under uniaxial compressive loading. The relationship between stress distribution and failure mechanism of the recycled aggregate concrete plate has been investigated and analyzed. The numerical model proposed in the paper is in the first time used to analyze the mechanical properties of recycled aggregate concrete. Efficiency and accuracy of the numerical model has been demonstrated. It is indicated that this model has potential to be extended for 3 dimensional structural analysis of recycled aggregate concrete.
Numerical Investigation on the Structural Behavior of a Composite Impact Absorber
Authors: Lamanna Giuseppe , Caputo Francesco , Soprano Alessandro
Published: October 2009

The energy absorption capability of an exposed crashworthy element or system is largely affected by material properties and structural design: prismatic sandwich structures, made of foam or honeycomb core between two metallic or laminated composite face plates, are good candidates. This work deals with a numerical investigation on the energy absorbing capability of such a structural component. There are several difficulties associated with the numerical simulation of a composite impact-absorber, such as high geometrical non-linearities, boundary contact conditions, failure criteria, material behaviour; that is because the main objectives of any numerical investigation are the calibration of the model with experimental results and the evaluation of the sensitivity of the variables with respect to the geometrical and physical parameters which influence the study at hand. The latter is a very relevant aspect for designers if the application of the model to real cases has to be a robust one from both a physical and a numerical point of view. In this paper a preliminary calibration of a numerical model for a composite impact absorber is presented, on the basis of experimental data found in literature; then a sensitivity analysis of the same model to the variation of the main geometrical and material parameters, developed by using the explicit finite element algorithms implemented in the Ls-Dyna code, is illustrated.
Numerical Simulation on Damage and Failure of Recycled Aggregate Concrete with a Lattice Model
Authors: Xiao Jian Zhuang , Liu Qiong , Tam Vivian W.Y.
Published: October 2009

A random aggregate model of recycled aggregate concrete is developed in this paper on the base of a mixture ratio. Combining a lattice model with random aggregate of recycled aggregate concrete, lattice elements in the lattice model of recycled aggregate concrete can be classified into five types: (1) nature aggregate, (2) old hardened mortar, (3) new hardened mortar, (4) old interface transition zone (ITZ), and (5) new ITZ. The fundamental mechanical parameters of the lattice elements are chosen from the authors’ test as well as other references. A FORTRAN program of the lattice model is then written with basic theories of finite element method (FEM) for simulating the meso-structural damage of recycled aggregate concrete under uniaxial compression.
Development of Simulations Models under Thermo Mechanical Loading Conditions
Authors: Biglari Farid R. , Davies Catrin Mair , Nikbin Kamran M.
Published: October 2009

Advanced steels are designed and produced to be used in engineering applications in which thermo-mechanical fatigue could be a main factor in causing failure in components operating at elevated temperatures. In this paper thermo-mechanical fatigue properties of these steels are studied under the influence of creep and fatigue damage evolution. Development of different models and simulation techniques are reviewed to predict material behaviour. Numerical simulations are carried out to predict experimental tests on parent material notched bar specimens. Numerical predictions are introduced in advance of experimental test to assess the experimental test procedure. This is usually done to enhance the experimental result integrity and expectations. A local ductile damage development methodology is employed using the kinematic hardening criterion and compared to previously used strain hardening material property. The modelling on notched bar geometries is extended to geometries with cracks in which a local damage criterion will be used to predict virtual crack extension in compact tension specimens.
The Influence of the Steel and Aluminium Components Separation at the Conductors Locking for Stress-Strain Tests
Authors: Faur Nicolae , Marsavina Liviu , Cernescu Anghel , Neş Christian , Linul Emanoil
Published: October 2009

At the stress-strain tests for the overhead electrical conductors stranded in alternate directions (aluminum conductor steel reinforced - ACSR), the locking mode of the specimen ends on the tensile machine represents a difficult problem which if is not correctly solved may seriously influence the results obtained.
The stress-strain tests are performed according to standards as the European Standard EN 50182:2001. The specimen must have a length imposed by the conductor diameter, but not less than 10m. During the stress-strain tests the specimen is loaded in steps at successive cycles of loading- unloading (30%, 50%, 70%, 85% of Rated Tensile Stress –RTS). Finally, in order to determine the breaking forces, the conductor is loaded up to total breaking. In these conditions, the test success is decisively influenced by the correct locking of the conductor in the grips. The locking of the conductor ends is usually performed by casting the conductor ends in the gripping devices, after the wires ends reflection. In this paper there is presented a new locking method of the conductor ends by separation of the steel wires from the aluminum ones and their separate winding on two drums with helical groove. The tests performed have confirmed that this method is cheaper, and not influencing the real behavior of the conductor.
Component Seismic Damage Model for SRHSHPC Joints
Authors: Zheng Shan Suo , Wang Bin , Li Lei , Wang Wei , He Jin Chuan
Published: October 2009

The deficiency of present damage model is generalized by studying existing references. The mechanical properties of steel reinforced high strength and high performance concrete (SRHSHPC) members under monotonic loading, including the capacity of ultimate deformation, strength, stiffness, etc. are analyzed after the different number of cycles. The reduction factor is introduced, the dynamic variation relationship of ultimate deformation with the number of cycles is obtained, and the merits of existing damage model are utilized, finally the seismic damage model, which is suitable for SRHSHPC beam-column joints, is established. In order to verify the rationality of damage model, Opensees as a nonlinear analysis program is adopted to simulate SRHSHPC joints, the comparison of the numerical analysis results with experimental results shows that the proposed damage model can capture the behaviors of joints very well. The model can, therefore, be used to carry out seismic damage analysis of other SRHSHPC members.
Flutter of Perforated Metallic Plates Repaired with Cross-Ply Composite Patches
Authors: Yazdi Ali Amin , Rezaeepazhand Jalil
Published: October 2009

This study investigates the application of laminated composite patches for enhancement of flutter behavior of perforated metallic plates repaired with an external composite patch. Due to material anisotropy and discontinuity in geometry involved in flutter analysis of repaired plates, closed form solutions are practically unobtainable. Numerical studies using commercial finite element software were conducted to investigate the effects of variation in lamination parameters on the flutter boundary of perforated plates repaired with cross-ply composite patches. Both ply-level and sub-laminate level configurations are investigated. Presented results illustrate that flutter boundaries of perforated plates can be changed by choosing proper stacking sequence for composite patches.
The Dynamic Response of Circular Lining Structure and Multiple Cracks in Half Space under Impact Loading
Authors: Yang Zai Lin , Xu Mei Juan , Sun Bai Tao
Published: October 2009

The dynamic response of a circular lining structure and multiple cracks in an elastic half space while bearing impact loading is studied in this paper. This problem can be seen as the problem of defending of blast. The methods of Green's function, complex function and multi-polar coordinates are used here. First, the scattering wave which satisfies the condition of stress free on the ground surface of half-space containing a shallow-embedded circular lining structure impacted by incident SH-wave is constructed based on the symmetry of SH-wave scattering and the method of multi-polar coordinates system. Then a crack or multiple cracks in any position and direction can be constructed by Green's function and means of crack-division in half space. Finally the displacement field and stress field are established in the case of coexistence of circular lining structure and cracks, and the expression of dynamic stress intensity factor (DSIF) at the tip of crack is given. The interaction of inclusion and two cracks is chosen as numerical examples finally. According to nu-merical examples, the influences of different parameters on DSIF are discussed.
Durability Studies for Complete Dentures
Authors: Faur Nicolae , Bortun Cristina , Marsavina Liviu , Cernescu Anghel , Gombosi Otilia
Published: October 2009

The complete dentures are realized by different acrylic resins and different technologies. These materials are fragile and frequently appear crack and fractures of these dentures. Also, theses materials as well as the technologies of performing these dentures are expensive. In order to avoid the ultimate failure of the complete dentures, for each case there is necessary a numerical simulation as a preliminary stage before the effective performance of the denture. In order to realize the numerical simulation of the complete denture there is necessary to know the mechanical and elastic properties of the acrylic resins. This paper presents the results of experimental investigations performed in order to determine the mechanical and elastic properties of complete denture materials.
A 3D laser scanner was used for the elaboration of the geometrical model of the complete dentures. In this way, using the reverse engineering technology there was realized a very accurate geometrical model. Finite element analysis was used to estimate the durability of the same complete dentures. The calculation model was finally validated by a fatigue experimental test.
Automatic Cyclic Crack Propagation Calculations in Aircraft Engines
Authors: Dhondt Guido , Bremberg Daniel
Published: October 2009

This document describes a mixed-element approach to perform mixed-mode crack propagation calculations in an arbitrary structure in a fully automatic way. In a preprocessing step a cylindrical volume about the crack front is meshed with hexahedral elements while the remaining parts of the structure at interest are filled with tetrahedrons. Subsequently, a finite element calculation is performed yielding the stress field at the crack tip. The postprocessor determines the stress intensity factors and the 3-dimensional crack growth, leading to a new crack front. This procedure is repeated until a user-defined criterion is reached. The method is illustrated by an aircraft casing component.
Fatigue Crack Initiation and Growth in a High Loaded Bolted Bar Connection
Authors: Glodež Srečko , Podrug Srđan , Knez Marko , Kramberger Janez
Published: October 2009

The fatigue crack initiation and growth in a high loaded bolted bar connection made of high strength steel S1100Q is presented. The material parameters for the fatigue crack initiation f’, f’, b and c are determined using low cycle fatigue test according to ASTM E 606 standard. The fracture mechanics parameters C and m are determined according to ASTM E 647 standard. Based on low cycle fatigue parameters the computational analysis is performed to determine the number of stress cycles required for the fatigue crack initiation. The remain service life up to the final failure is than determined using the known parameters C and m and calculated stress intensity factor, where 3D numerical analysis is performed. The bolted bars are also experimentally tested. Comparison of computational and experimental results shows a reasonable agreement.
Micro-Destructive Flat-Jack Test for the Diagnosis of Historic Masonry
Authors: Nobile Lucio , Gentilini Cristina , Bartolomeo Veronica , Bonagura Mario
Published: October 2009

The present paper describes one of the most important slightly destructive technique used in the masonry survey: the flat-jack test. The test method is described in a critical way, emphasizing advantages and drawbacks. Besides, the relation between the flat-jack test and a numerical modelling is explored.
Structural Similitude for Vibration of Delaminated Composite Beam-Plates
Authors: Yazdi Ali Amin , Rezaeepazhand Jalil
Published: October 2009

This study describes the establishment of similarity conditions among structural systems. The main objective of this research is to study the applicability of similitude theory in establishing necessary similarity conditions for designing scaled down models for predicting the vibration behavior of delaminated composite beam-plates. The results presented herein indicate that, for vibration response of delaminated plates, based on structural similitude, a set of scaling laws can be found to establish necessary structural similitude and design rules for small scale models. For models with the same material properties and stacking sequence as prototype, distorted models with different delamination length than those of prototype can predict the behavior of the prototypes with good accuracy.
Residual Stress Effects in Stiffened Structures - An Alternative Approach
Authors: Horst Peter , Häusler Sascha Marc
Published: October 2009

The fatigue crack growth behavior in integrally stiffened, welded panels is influenced by residual stresses caused by the welding process. The paper presents a semi-numerical method for the determination of stress intensity factors, taking into account the residual stresses in such a way that the relaxation of the residual stresses during the crack propagation phase is covered. This approach is different from the one presented in [1].
Bending and Contact Strength of a Ceramic Nanocomposite
Authors: Dusza Ján , Hegedűsová Lucia , Kašiarová Monika , Csehová Erika
Published: October 2009

The paper deals with the determination of the characteristic strength and as well as the Weibull moduli and of the Si3N4+SiC micro/nanocomposite determined by the four-point bending test and the contact test using opposite spheres both applied to specimens of different size, respectively. Material failure in the bending and contact modes is caused by the presence of processing defects as fracture origins, and by the formation of cone cracks, respectively, where a stable growth of the cone cracks initiated during contact loading is assumed to be a reason of , . A microstructural analysis of the processing flaws, and a mathematical analysis of the propagation of the cone cracks regarding different dimensions of a specimen are also presented.
Long / Short Term Experimental Study on Chloride Penetration in Cracked Concrete
Authors: Yoon In Seok , Schlangen Erik
Published: October 2009

This study is focused on examining the effect of cracks on chloride penetration into concrete. In order to get reliable results, short-term and long term experiments were set up and chloride penetration behaviour through cracks was examined. It was noticed that chloride penetration through cracks tends to decrease with time. One of the explanations is crack-healing. Especially, this trend was obvious in concrete samples with larger crack width. However, measuring the border between chloride contaminated zone and healthy zone was clear in concrete of short-term experiment, while it was ambiguous in long term experiment.
Numerical Modelling of Crack Propagation and R-Curve Behaviour in Layered Al2O3/ZrO2 Composites
Authors: Kotoul Michal , Vyslouzil Tomas
Published: October 2009

The paper is devoted to numerical modelling of R-curve behaviour in laminates with strong interfaces, in particular multilayers made of alumina (A) and zirconia (Z). Contrary to previous studies based upon the application of approximate weight function method originally developed for homogeneous specimens, a full field analysis by FE of a three-point bending test of a sandwich beam is attempted and compared with the results obtained by approximate weight function method. Also the crack penetration across the layer interfaces is discussed, particularly in the case of a weak singularity.
A New Numerical Analysis for Cracks Emanating from a Surface Semi-Spherical Cavity in an Finite Elastic Body
Authors: Liu Bao Liang , Yan Xiang Qiao , Xiao Xin Ke
Published: October 2009

Due to the stress concentration effect around the hole, cracks are likely to initiate at the hole under the action of fatigue loading. This paper is specifically concerned with cracks emanating from a surface semi-spherical cavity in a finite body by using the boundary element software FRANC3D developed by a fracture mechanics investigation group of Cor-nell University. The numerical results can reveal the effect of the geometry of the surface cavity on the stress intensity factors.
The Analysis of Non-Linear Seismic Response of an Infilled Frame Structure in Yingxiu Town – The Heavy Disaster Areas of Wenchuan 8.0 Earthquake
Authors: Yan Pei Lei , Sun Bai Tao , Chen Hong Fu
Published: October 2009

On 12 May 2008, a magnitude 8.0 earthquake happened in Wenchuan, China .It was the most serious earthquake in china since 1949, causing very huge casualties and engineering damages. The complex building of the Xuankou secondary school in Yingxiu town was designed by the Code for Seismic Design of Buildings of China (GB50011-2001), the seismic fortification intensity of the buildings was 7 degree. In the earthquake, it was destroyed most seriously, and the engineering damage was characteristic. In the paper, the property of material nonlinearity was considered ,the nonlinear analysis model of infilled frame structure was established, the time history analysis and nonlinear static analysis were used during inelastic stage, the main cause of structural destruction was obtained, the influence of the infill wall on the structure was discussed.Therefore ,the results can provide valuable reference for the seismic design of infilled frame structure.
Plasticity-Induced Fatigue Crack Closure in High-Strength Steels: Is it a Real Phenomenon?
Authors: Toribio Jesús , Kharin Viktor
Published: October 2009

High-resolution elastoplastic simulations of a plane-strain tensile crack under cyclic loading visualised the Laird-Smith mechanism of fatigue crack growth, which manifested the effects of K and overload, but no signs of crack closure. Simulations discarded the supposed mechanism of plasticity-induced crack closure (PICC) via out-of-plane stretching of material elements filling-in the crack and coming in contact at unloading. Specimen compliance curves turned out to be nonlinear merely by virtue of plasticity with no contribution of crack closure. Thus the results manifested the ambiguity of main justifications about the phenomenon of PICC.
Effect of Side-Wall Reinforcement on Energy Absorption of Thin-Wall Cylindrical Damper
Authors: Chau M. , Hoffmann Joerg , Blundell M.V. , Ordys A. , Hadavinia H.
Published: October 2009

This study is focused on modification of a conventional bumper damper to increase its energy absorbability. This bumper damper device is currently used on passenger vehicles for reducing structural damage, as well as part of the pedestrian protection system. A hollow aluminium cylinder with 2mm in thickness was subjected to a range of experiments. The energy absorption takes place as a ram displaces along the cylinder’s bore, where the outer diameter of the ram is slightly wider than the inner diameter of this cylinder.
Characterization of the Fracture and Fatigue Behavior of Thermoplastic Elastomer Materials
Authors: Major Zoltan , Isasi Mikel , Schwarz Thomas
Published: October 2009

Thermoplastic elastomers are a relatively new group of engineering materials and are increasingly used in various technical applications (i.e., seals, gaskets, damping elements, and membranes) where the fatigue resistance plays an important role. The fracture behavior of elastomers is often characterized using the tearing energy concept, T. However, hardly any data are available for these types of materials. Hence, an unfilled and a filled thermoplastic polyurethane (TPU) type were investigated under cyclic loading conditions. The pure shear specimen configuration was used in the experimental part of this study. Crack growth kinetics curves were determined and the cycle number and the tests frequency dependence of these curves investigated. While a stable crack growth process was observed at 2 Hz the crack growth became unstable above specific test amplitude at 10 Hz.
Contact Fatigue Crack Growth in PVD-Coated Spur Gears
Authors: Baragetti Sergio , Cavalleri Stefano , Tordini Federico
Published: October 2009

The aim of this work is to investigate the (rolling) contact fatigue behaviour of transmission spur gears coated with PVD (Physical Vapour deposition) thin hard films. Numerical models of coated steel and titanium spur gears were developed. The effect of the residual stress gradient induced by the coating deposition process was considered in the calculations. A theoretical-numerical procedure was arranged to foresee the crack propagation direction. Such a procedure could represent a powerful tool to predict the (rolling) contact fatigue resistance of PVD-coated gears.
Fatigue and Contact Fatigue Resistance of Thin Hard-Coated Components
Authors: Baragetti Sergio , Tordini Federico
Published: October 2009

In this paper a review of the state of the art on the study of the fatigue and the contact/rolling contact fatigue (RCF) resistance of thin hard-coated components is provided. Physical and chemical vapor deposition (PVD and CVD) methods are used to deposit such films. A fair number of references reports experimental data highlighting the improvements achieved with coating deposition on both steels and light alloys. Numerical modelling has also been devoted to shedding light on the behaviour of coated components and reliable previsional procedures have been arranged to foresee the number of cycles until fatigue damage initiation and failure.
Experiment Study on Compressive Membrane Action of Slab Strips Restrained by Shear Walls
Authors: Wang Qing Xiang , Wang Gang , Li Zhong Jun
Published: October 2009

Subjecting to the compressive membrane action (CMA), the ultimate load capacity of the reinforced concrete (RC) slab with lateral restraint would be improved obviously. Test of 12 one-way slab specimens restrained by shear-walls was carried out to investigate the properties of the slab strips’ compressive membrane action. The reduced-size specimens were designed to keep the ratios of shear-walls’ restraint stiffness to slab strips’ flexural stiffness unchanged. One horizontal testing instrument was first used to record the development of the slabs’ lateral restraint forces. The ultimate loads of slab strips with certain lateral restraint stiffness gave an average 38.3% rise from the calculations of upper-bound method. Though the increment of slab’s ultimate load was due to the additional moment formed by the lateral restraint force, the results showed that the peak of lateral force lagged of the slab strips’ ultimate load, which was different from the previous hypothesis. Various parameters which affect the development of CMA were also investigated, such as the shear-wall’s thickness, axial load on the walls, the slab strips’ span-height ratio and reinforcement percentage.
Mechanism Analysis of Casing Damage Induced by High Pressure Water Injection in Daqing Oilfield
Authors: Han Xiu Ting , Li Qing Fen , Li Jun Liang , Gao Ying
Published: October 2009

Well casing damage is a commonly existing problem in oilfield exploitation in the world. Daqing oilfield is a multiple-zone, heterogeneity sandstone oilfield, where the major influence factors which lead to casing damage are geologic factor, engineering factor, high pressure water injection and chemical factors. Among them, the high pressure water injection is the most important one. Water injection exploitation in Daqing oilfield showed that casing-damage increased with the increasing water injection pressure. However, the mechanism is not totally understood and the control method is not well developed yet. In the present work, the mechanism analysis of casing damage induced by high pressure water injection in Daqing oilfield is proposed. It is found that after high pressure water injection, the sandstone layer will expand and result in the vertical elongation of the casing. The additive tensile stress of the casing induced by vertical strains will cause casing-damage. Besides, the horizontal deformation of clay-stone increases with increasing water content of the formation layers and soaking time. The cohesion of clay-stone and inner friction angle decreased with increasing water quantity. In that case, some high obliquity formation layers which may induce high hypsography pressure difference will cause localized slip along weak formation layer interface in the area of waterishlogged clay-stone. Casing damage and well failure caused by the relative movement of the formation layer interface may therefore occur. The micro-fracture of formation induced by high pressure water injection also educed formation rupture and casing damage.
Wavelet Analysis in Damage Detection for Bridge Structure
Authors: Hu Wei Bing , Hu Wei , Zheng Yu
Published: October 2009

The damage of structure leads to variation of structural modal parameter，so the wavelet transform for damage detection is introduced in this paper for considering the variation. First, structural dynamic response signal on the basis of the vibration-based structural damage diagnosis methods is calculated by structural analysis in the paper, then, each of sub-signals is calculated according to wavelet analysis, also, the sub-signal energy spectrum of dynamic response signal and energy spectrum variation are known. By observing the difference of the sub-signal and the variation of the sub-signal energy spectrum, we can get the variation of structural modal parameter and the sub-signal energy spectrum due to the performance degradation of the whole structure and local variations of damage level and location ,so that this method can be used in on-line damage detection for bridge structure.
Investigation on Earthquake-Induced Buildings Decoration and Indoor/Outdoor Properties Losses in Urban Zones of Wenchuan Ms8.0 Great Earthquake and Study on Decoration Damage Loss Ratio
Authors: Chen Hong Fu , Sun Bai Tao
Published: October 2009

A great earthquake of magnitude 8.0 occurred on May 12, 2008 (Beijing Time) in Wenchuan, Sichuan Province of China, caused huge casualties and economic losses. As a member of field investigation team of China Earthquake Administration (CEA), the decoration and indoor/outdoor properties losses of the earthquake-stricken areas were investigated in detail, which include Dujiangyan, Mianyang, Deyang, Chengdu, Guangyuan city, and other areas. In this paper, based on statistical analysis of collected survey data, the investigation results and characteristics of buildings decoration and indoor/outdoor properties losses of the earthquake-stricken areas are given firstly. Then, the relationship between decoration damage grade and main body structure damage grade is analyzed, and loss ratio of building decoration damage in urban zones is also provided on the basis of expert questionnaires. Thus, some foundations are established for loss assessment method of building decoration damage in urban zones.
Experiment Study on Cyclic Behavior of Concrete Filled Steel Tube (CFST) Column-Reinforced Concrete (RC) Beam Connections
Authors: Wang Qing Xiang , Liu Shi Run
Published: October 2009

The test results of six connections under cyclic loading are presented in the paper. Each test specimen was properly designed to model the interior joint of a moment resisting frame, and was identically comprised of three parts that including the circular concrete filled steel tube columns, the reinforced concrete beams, and the short fabricated connection stubs. Energy dissipation was designed to occur in the beams during a severe earthquake. Steel bars which were embedded into concrete core and welded to the connection stubs, were used to transfer the force distributed by the reinforcing bars of concrete beam to the concrete core. The results indicated that the embedded steel bars were very efficient in eliminating the stress concentration on the tube wall and there was no visible deformation occurred on the tube wall until the collapse of the specimen. Furthermore, the connection of each specimen had enough capacity and thus the plastic hinge appeared in the beams. As results, the ductility of this new type structure directly depended on the RC beams.
Optimum Approach and Modeling for Fabrication of Fused Fiber Coupler
Authors: Shuai Ci Jun , Peng Shu Ping , Qi Hu An , Qiu Qing Jun
Published: October 2009

The consistence of performance such as excess loss, coupling ratio and drawing length of fused fiber couplers is poor, even if they are fabricated at the same technical parameters; And the fused temperature provided by gas fluctuates by 5-30°C, while the drawing speed is rather stable. To find out the reason of poor performance consistence, the rheological numerical analysis is carried out under the non-isothermal condition. The effect of technology parameters such as drawing speed and fused temperature on the fabrication process is studied. A conclusion can be reached that it is the fluctuation of fused temperature that induces poor consistence. An electrical resistance microheater is designed and fabricated, and its fluctuation of temperature is by 1.5°C. The performance consistence of fibre coupler is improved greatly with the novel heater.
Crack Pattern and Ductility of Steel Reinforced Ultra High Strength Concrete Composite Joint Subjected to Reversal Cycle Load
Authors: Yan Chang Wang , Jia Jin Qing , Zhang Ju
Published: October 2009

In order to investigate the seismic damage and performance of steel reinforced ultra high strength concrete composite joint subjected to reversal cycle load, six interior strong-column-weak-beam joint specimens were tested with various axial load ratio and volumetric stirrup ratio. A discussion on the crack mode and ductility was presented. It was found that all joint specimens failed in bending with a beam plastic hinge in a ductile manner, with crack propagation different from the weak-column-strong-beam joint. The experimental results indicated that test parameters of the steel reinforced ultra high strength concrete composite joint with good seismic performance may be referred for engineering application.
Thermal Fatigue Damage Behavior of Plasma Sprayed Thermal Barrier Coatings
Authors: Yamazaki Yasuhiro , Yoshida Toshihiko
Published: October 2009

Thermal fatigue and isothermal oxidation tests of a plasma sprayed thermal barrier coatings have been carried out. The experimental results indicated that micro-cracking as the fatigue damage occurred in each cooling stage of thermal cycles. And the spallation fracture morphology was changed by the cycle wave form; the spallation failure occurred in the ceramic top-coating under the triangle cycle wave condition, on the other hand, it occurred near the top-coating/TGO interface under the trapezoidal wave condition. The finite element analysis indicated that the local residual stress, which is the driving force of interfacial damage, increases with the thickness of the thermal grown oxide. The degradation mechanism by thermal fatigue was discussed, in addition, a simple life prediction model for the thermal fatigue of TBC systems was proposed.