bluuebunny/crossref_metadata_2025 huggingface dataset:
Research on Automobile Panel Case Retrieval Methodology
Authors: Zong Xian Liang , Wang Ping , Zheng Hui
Published: October 2009

CBR (Case-based reasoning) technique is increasingly applied in the process planning and dies intelligent design for stamping parts. In these applications, stamping parts information acts as the problem domain of cases model, while stamping process and die information as the answer domain. The similarity computation and retrieval of stamping parts are essential to the case-based design of stamping process planning and dies. In this paper, that issue is studied targeting automotive panel as the research object, and a retrieval method for similar panel parts based on the automobile panel coding is proposed. The coding structure is designed considering the automobile panel's features, especially the geometry shape features and their relationship. And the corresponding similarity calculation method is put forward. Finally, a case study is used to reveal the effectiveness of this methodology.
Study on System Design and Control Methods of Polishing Robot System
Authors: Luo Zhong , Wang Fei , Jiang Yang , Liu Hong Yi
Published: October 2009

A design method is presented for a polishing robot in unstructured working environment. Setting up a structure model of the polishing system, and the operation principle and control method are described. The human-simulated intelligent control method is applied to the control of contact force in unstructured environment, because of the uncertainty, variability and unstructured of the environment. The basic idea of the intelligent control method is based on the size of error and change direction of control variables. The conditions of the control rules and control decision are inferred by forward reasoning. The HSIC controlling function is achieved, which can strengthen people energy to revise and control the interaction force and position of the end-effector.
Fuzzy Synthesized Evaluation of Product Quality of Machine Tool Based on Harmonious Design Method
Authors: Liu Chun Shi , Li Xiao Peng , Sun Wei , Zhang Yi Min
Published: October 2009

In this work, it is presented and studied that the harmonious of product function with capability, harmonious of product with product, harmonious of product with people, with technology, with society environment, with entironment from the view of entironment, society, economy, science, politics, culture and legal point in the design process. And the quality verification and evaluation methods are studied to enhance the design quality more effectively. And that, all the studied contents is named harmonious design method. One machine tool is used as an example to explain the method with design quality evaluated by fuzzy synthesized evaluation method from function, structure capability, working capability and craftwork capability factors. The grade and disparity of design quality are obtained through the evaluation results, then design project could be modified based on it, and it is very useful to improve product quality and to enhance performance-price ratio and market competitive ability.
Design and Simulation for Multi-Axis HS-WEDM System
Authors: Wang Tong , Lu Xian Chong , Qiu Feng
Published: October 2009

In order to improve machining quality and productivity of complex curved surfaces in high-speed wire electrical discharge machining (HS-WEDM), an additional numerical control (NC) worktable (rotation-swing-swing worktable) and its NC system were designed. The movement model of the four-axle linkage system was established and simulation was developed using the programming language Visual C++ and standard connection software OpenGL.
Study a Fuzzy Inference System on the Supplier Evaluation in E-Manufacturing
Authors: Chen Jian , Wu Ming Hong , Jiang Wen Rong , Wang An Bao , Yan Ji Hong
Published: October 2009

The supplier selection and evaluation is a key factor of the intelligent supplier selection & evaluation system in e-manufacturing. The model used for supplier selection is Fuzzy inference system which is introduced in the paper. The paper started with the brief introduction of the intelligent internet supplier selection & evaluation system. It concentrated to introduce the application of the fuzzy set model for supplier selection. This paper will introduce the design of the fuzzy sets model, and the evaluation results.
A HLA-Enabling Method in Collaborative Simulation Environment for Complex Product Development
Authors: Fan Miao Miao , Fan Yu Shun
Published: October 2009

HLA-based collaborative simulation is an effective way to integrate different disciplinary models together for the design and development of complex product. In this paper, the HLA-enabling method based on HLA agent model is proposed to make models created through commercial software compatible with HLA standard. Next, a prototype system for forging manipulator system based on such HLA-enabling method is developed accordingly, where an approach of developing ABAQUS engine agent is proposed, which solves the difficulty of wrapping ABAQUS software. Finally, a case study on forging and manipulating process is conducted and verifies the high fidelity and effectiveness of our collaborative simulation technology.
Development of Compliant Tool System of Digitalized Precision Polishing for Aspheric Surfaces
Authors: Zhang Jian Bo , Zhan Jian Ming , Lv Bi Da
Published: October 2009

Aspheric surfaces of high precision and low roughness are widely used in the military field, the aeronautics and astronautics field and some high-tech fields. Therefore, research works on the methods and equipments of digitalized polishing for aspheric surfaces are a hot issue in the modern precision manufacturing. The traditional precision manufacturing mainly depends on the higher precision equipments to promote the surface quality of aspheric surfaces, but the cost of equipments seems to be extremely expensive. Taking the general CNC lathe of two axis interpolation as a platform, and basing on the controllable damping characteristic of the Magnetorheological Fluids (MRF), a new kind of compliant polishing tool system for aspheric surfaces is developed in this paper. The tool system keeps the polishing force to be stable by the torque servo unit of MRF, and implements the compliant polishing.
The Study of Meshing Performance for Single Screw Compressor Based on Contact Analysis
Authors: Wang Ke , Zhao Bin
Published: October 2009

In order to increase transmission performance and lubricating condition for meshing pair of the single screw compressor, the contact analysis for the single screw compressor is analyzed. The equations of the former tooth surface of the gate rotor, the back tooth surface of the gate rotor, the top tooth surface of the gate rotor and transition surface between two tooth of gate rotor are constructed respectively. The tooth surface equation of the screw rotor is deduced through using the tooth surface equation of the gate rotor and transform matrix depending on conjugated theory, the contact line equation is moreover acquired. The calculation formula of inducing method curvature is deduced, the inducing method curvature of some points on contact line with the rotation degree of the gate rotor changing is calculated. The computing results show that the contact surface is osculating, which is favor to increase contact strength of the tooth surface. The distribution rules for contact lines of the former tooth surface and back tooth surface of gate rotor is gained through calculation, which provide theory basis for manufacturing screw rotor.
A Ring Type Standing Wave Ultrasonic Motor Using Cantilever Type Bending Transducer
Authors: Chen Wei Shan , Liu Ying Xiang , Liu Jun Kao , Shi Sheng Jun
Published: October 2009

To obtain large mechanical output power, a ring type standing wave ultrasonic motor using cantilever type bending transducer is proposed. There is a cantilever on one side of the ring, and four PZT ceramics are set on each end surface of the cantilever. The bending mode of ring is excited by the bending vibration of cantilever transducer. Thus, linear simple harmonic motions are achieved at the particles on the teeth. The working principle of proposed motor is analyzed. The ring and transducer are designed with FEM. The bending vibration modals of transducer and ring are degenerated, and the motion trajectories of nodes on the teeth are analyzed. The analysis results indicate that a standing wave is excited in the ring by the bending vibration of transducer, and the proposed motor has potential good output characteristics. The results of this paper verify the theoretical feasibility and provide instructions for the development of proposed motor.
Study on the Integrated Development System for Carbody of Multiple Unit Based on Digital Prototype Technology
Authors: Hu Guang Zhong , Xiao Shou Ne , Wu Li , Xiao Shi De
Published: October 2009

With multiple unit running speed, the carbody structure design, strength and fatigue reliability have become an important part of the multiple unit design. From the design requirements of carbody, based on digital prototype technology, the architecture and the development process of carbody integrated design and simulation platform are put forward. Combined with the process of body design, which includes scheme design, three-dimensional structure design, calculation and verification of strength, fatigue reliability analysis and fatigue life prediction, the main module, the key technologies and methods of the body design and dynamic simulation system are discussed. It has important engineering significance for improving the efficiency of the body design and promoting the carbody design.
Modeling of Dimensional Errors in Slender Bar Turning Process Using Artificial Neural Networks
Authors: Cui Bo Di , Guo Jian Liang
Published: October 2009

Accurate predictive modeling is an essential prerequisite for optimization and control of production in modern manufacturing environments. For slender bar turning operations, dimensional deviation is one of the most important product quality characteristics due to the low stiffness of part. In this study, radial basis function neural network is employed to investigate dimensional errors in slender bar turning. The relationship between cutting parameters and dimensional errors is firstly described by the proposed model. Simulation is provided to investigate the effects of cutting parameters on dimensional errors. Further, real-time predictive model based on radial basis function neural network is developed to perform the dimensional error monitoring during slender bar turning process. Experiments verify that the proposed in-process predictive system has the ability to monitor efficiently dimensional errors within the range that they have been trained.
The Rapid Metal Tooling Process Based on Layered Manufacturing
Authors: Shi Guang Lin , Wang Zhen Jiang , Deng Lang Ni
Published: October 2009

The objective of this research work is to develop a direct metal rapid mould using layered manufacturing process. The approach relate to direct slices of CAD models to generate process planning instructions, incises the metal sheets layer by layer process and bonds them by diffusion weld technology. Instead of slicing the model from STL data, this methodology direct slices of CAD models using a constant layer thickness in EUCLID-IS based CAD system. The cross section contour profiles are then converted to CNC machine instructions for fabrication. Fabricated sample shows that the new process is one of the feasible methods for the layered manufacturing of metal moulds.
YAG Laser Cutting of Multi-Layer Soda-Lime Glasses
Authors: Cai Na , Yang Li Jun , Wang Yang , Tian Zhong Guo
Published: October 2009

In laser cutting of glass with controlled fracture, thermal stress induces a fracture and the material is cleaved along the cutting path by fracture propagation. Compared with CO2 laser, YAG laser has many advantages in cutting glass with controlled fracture. As a volumetric heat source, YAG laser can penetrate through the glass. Therefore, the temperature distribution is uniform across the thickness of the glass and the fracture propagates from the top and bottom surface to the middle so that better cutting quality can be acquired and multi-layer glasses can be cut simultaneously. In this paper, a 1064nm YAG laser is applied to cut two-layer and four-layer glasses. Fracture propagation mechanism is studied by examining the temperature and stress fields using finite element software ANSYS11.0. Good cutting qualities of fracture surfaces for all the layer glasses are acquired and the cutting efficiency is greatly improved by this technique as well. Additionally, due to smaller laser spot size the glasses that are closer to the focal point have higher laser power density inside glass, which may lead to ablation and evaporation phenomenon. But lower laser power density is not enough for fracture initiation and expansion. Therefore, it’s important to find a proper laser power for all the layer glasses. Small tensile stresses on the top and bottom surfaces will make the material separate from up and down to middle, whereas the compressive stresses in the middle ensure stable fracture propagation. Moreover, the stable fracture propagation always lags behind the laser beam spot. High tensile stresses are distributed throughout the thickness of the glass in the leading and trailing edges, which leads to unstable fracture extension in the leading and trailing edges.
Analytical Modeling of Shear Band Spacing of Serrated Chip in High Speed Cutting of Aluminum Alloys
Authors: Jiang Xu Dong , Wang Yi Qiang
Published: October 2009

Based on Oxley’s predictive model, the novel analytical modeling of shear band spacing of serrated chip in high speed cutting of aluminum alloys is investigated accounting for the effect of strain rate hardening in addition to temperature softening. It is indicated that the shear band spacing decreases with increasing the cutting velocity and increases with increasing undeformed chip thickness. Other than the cutting velocity and undeformed chip thickness, the shear band spacing initially descends to minimum and subsequently ascends with increasing the tool rake angle.
A Framework for Configuring Service-Oriented Manufacturing Executive System
Authors: Zhang Fu Qiang , Jiang Ping Yu
Published: October 2009

Service-oriented manufacturing is a new manufacturing paradigm in workshop level. To clarify configuration issues of service-oriented manufacturing executive system (so-MES), a conceptual framework and hierarchical structure model are put forward. The framework consists of three modules: the manufacturing resource distribution, the process-flow planning, the sensor and inspection planning. And then, methodology for enabling the framework is presented in detail. Finally, a simple example is provided to verify the proposed method.
Chord Error Closed-Loop Controlled NURBS Interpolator and Trajectory Planning
Authors: Liu Yu , Liu Jie
Published: October 2009

Focusing on the problem of NURBS curve interpolation in high speed manufacture, a new trajectory planning algorithm, which is suitable for chord error closed loop controlled interpolator is proposed. This tragjectory can determine accelerating, decelerating or maintenance last velocity in the next period via judging the braking distance. By the way of testing different calculating time under different CPU core, the real-time characteristic is validated. The simulation shows that chord error closed loop interpolator can automatically adjust the velocity to satisfying the precision demand, through calculating the curvature. In addition, it can assure that the maximal velocity and the acceleration were equal to the referenced parameters and machine runs with the dynamic characteristic of operator set completely.
A Multi-Agent-Based Automatic Negotiation for Distributed Manufacturing
Authors: Wang Gui He , Su Peng Cheng , Li Hu , Wang Wan Shan
Published: October 2009

The concept of agent and multi-agent was introduced. The agent structure, negotiation strategies, and the negotiation mechanism were also researched. Based multi-agent, an automated negotiation method for bilateral contracts is proposed, which can efficiently carry out multilateral negotiations with multi-attributes in distributed environments. This framework supports efficiently multilateral negotiation. In the end, the negotiation is conducted and demonstrated that multi-agent can improve negotiation efficiency by saving negotiation time and cost.
Cyclic Damage Evolution in Polymer Matrix Composites
Authors: Plumtree Alan
Published: October 2009

Damage mechanics has been applied to describe the cyclic behaviour of glass fibre-polyester and carbon fibre-epoxy composites with different lay-ups under various loading conditions. Damage evolution was determined by continually monitoring fatigue modulus degradation and measuring the crack density. These methods complemented each other. They showed that the damage could be separated into two stages. Damage evolved rapidly for the first 10% of life, followed by a more gradual and linear accumulation for the remainder of life. In general, the transition from the first to the second stage indicated a change from transverse matrix cracking to fibre-matrix debonding and coalescence. Damage mechanics was applied to the fatigue modulus changes that occurred in the stress-strain hysteresis loops, monitored throughout life. A two-stage model was applied to express damage evolution using the modulus- and crack-based damage parameters. This model successfully described cyclic damage evolution for different lay ups of the PMCs. The significance of which was that the amount of fatigue damage for any stress level at the end of the initial stage could be used to accurately predict fatigue life and construct a stress-life diagram for the given composite
Fatigue Parameters of Cement-Based Composites with Various Types of Fibres
Authors: Seitl Stanislav , Keršner Zbyněk , Bilek Vlastimil , Knésl Zdeněk
Published: October 2009

The paper introduces the basic fracture mechanics parameters of advanced building material – cement-based composites with various types of fibres, prepared as high performance concrete/mortar developed by ZPSV, a.s. company for production of thin-walled panels/elements. To this end three-point bend specimens with starting notch were prepared and tested under static (load–deflection diagram, effective fracture toughness) and cyclic loading (fatigue parameter – Wöhler curve). The experimentally obtained results of cement-based composites are compared and the suitability of these types composites for its application are discussed.
Shaking Table Experimental Study on Diagnosis of Damage and its Evaluation in Steel Structure
Authors: Jankowski Robert
Published: October 2009

The methods of diagnosis of damage through measuring the changes in dynamic structural properties have been intensively studied for many years now. On the contrary to mechanical or aeronautical engineering, however, the practical application of the methods in the case of civil engineering structures meets a number of difficulties indicating the need for further research. This concerns in particular the need for the shaking table investigations since the results of such tests are very limited. Therefore, the aim of the present paper is to show the results of the shaking table study conduced on a model of two-storey steel frame building. The 1.56 m high model structure was constructed of columns with cross section of mm. Damage was defined as a reduction in stiffness and introduced by replacing the columns with elements having mm cross section. Seven different structural damage cases described by different number of columns with the reduced cross section were considered in the study. During the shaking table experiment the base of the structure was excited under the sweep-sine loading. The results of the study show a characteristic decrease in the natural frequencies with the progression of damage. This trend has been especially observed for the first natural frequency, for which the decrease in the frequency value has been found to be uniform. The results of further analysis show the scattered values of the structural damping ratios without showing any relation with the level of structural damage.
Creep Behaviour in Reinforced Masonry Walls Interpreted by Acoustic Emission
Authors: Bocca Pietro G. , Lacidogna Giuseppe , Grazzini Alessandro , Manuello Amedeo , Masera Davide , Carpinteri Alberto
Published: October 2009

An experimental analysis on a set of strengthened masonry walls has been carried out by means of cyclic loading tests in order to simulate the creep effects. The damage evolution of specimens reinforced by traditional or innovative methods is evaluated by the Acoustic Emission (AE) technique. The AE time dependence during fracture propagation is analysed through a power law. In addition, the AE frequency analysis is used to obtain information on the criticality of the ongoing process.
Delaunay-Tessellation Based Elastic-Plastic Analysis by Body Force Method
Authors: Saimoto Akihide , Ino T. , Imai Y.
Published: October 2009

The occurrence of small scale plasticity can be modeled physically by force doublets embedded in an elastic medium and therefore the plasticity problem can be treated by the superposition of elastic solutions. This idea for the treatment of an inelastic strain is reviewed and generalized to develop a versatile program for two-dimensional elastic-plastic problems based on Body Force Method. In the present study, a treatment of an elastic-perfect plastic body is discussed in detail. The increment of the density of force doublets, which has one to one correspondence to the increment of plastic strain, can be determined from Prandtl-Reuss equation. It was also found the Delaunay triangulation is useful and convenient for the automated elastic-plastic analysis.
Elastic Conditioning, Memory and Relaxation Induced by the Presence of Cracks in Concrete
Authors: Scalerandi Marco , Gliozzi Antonio S. , Antonaci Paola , Bruno Caterina L.E. , Bocca Pietro G.
Published: October 2009

The presence of damage or cracks modifies the elastic properties of a sample, introducing nonlinear components in the elastic response to an ultrasonic excitation. Among other effects, we discuss here conditioning and memory, i.e. the transition of the sample to a new (non equilibrium) elastic state when perturbed by a strain, even at a relatively low amplitude. A quantification of these phenomena can be the basis for a novel Nondestructive Method to evaluate the integrity of a structural or mechanical component.
On the Buckling Behaviour of Telescopic Hydraulic Cylinders
Authors: Morelli Piero
Published: October 2009

Telescopic cylinders are generally employed as linear actuators, when the desired moving span is several times the length of the closed device, like in cargo trucks lifting applications, for instance.
During the active phase of the actuation, hydraulic power is normally used to feed pressu-rized fluid inside the cylinder, thus providing the progressive extension of the cylinder ele-ments and the required operative axial thrust. In this condition, therefore, cylinders must bear external compressive loadings in an increasingly slenderness configuration, which can give rise to buckling failures.
In this study, experimental measurements of the limiting axial loadings of telescopic cylind-ers, in full extended conditions, have been performed both in laboratory and during real oper-ations on the field. The strains of the material in the critical sections and the lateral deflec-tions of the tested structures have been recorded as a function of the applied loads. The re-sults of this investigation are presented and discussed, in order to identify the signals of inci-pient buckling and find out the ultimate load carrying capabilities of this kind of components.
First Principles Calculation of Hydrogen Embrittlement in Iron
Authors: Takano Noriyuki
Published: October 2009

Hydrogen embrittlement in iron and steels has been studied for long years. Although a few mechanisms of it have been proposed, it has not been clearly understood yet. Especially, the decohesion theory and the hydrogen enhanced localized plasticity theory have been discussed in the center of attention. Hydrogen is considered to induce a cleavage fracture in the former, but enhance slips in the latter. It is essential problem which hydrogen induces cleavage or slip in hydrogen embrittlement. The purpose of the present paper is to clarify the effects of hydrogen in iron single crystal on the fracture or deformation using first principles calculation. In the cleavage model, the changes of total energy were estimated with a distance of a pair of {001} planes in a unit cell composed of 12 iron atoms and a hydrogen atom. In the slip model, the changes of total energy were estimated with a displacement of a few {110} layers toward <111> direction. Hydrogen reduces the total energy in the cleavage model, but does not change that in the slip model.
Estimation of Crack Growth Life in Rail with a Squat Defect
Authors: Jun Hyun Kyu , You Won Hee
Published: October 2009

Rolling contact fatigue initiated defects such as surface corrugation, head check, squat, are one of growing problems in high speed railway line. A squat is generally developed below the rail surface and grows parallel to surface until it turns down into rail. Estimation of critical crack size and crack growth rate is an essential to prevent rail from failure and develop cost effective railway maintenance strategy. In this study, we predict crack growth rate of a rail with a squat defect. For this purpose, a rail model with a squat defect is developed. Timoshenko’s beam theory is applied to calculate the global bending stress at the crack tip and Hertzian contact model is applied to calculate the local contact stresses at the surface of rail by simulating rolling over a railway wheel on a rail. Stress intensity factors are calculated from the total stress at the crack tip. Fatigue crack growth curve of 60kg rail steel is applied to calculated crack growth rate. Software to predict crack growth life through whole life cycle is developed. We expect that we can make a more cost effective rail maintenance strategy by considering the crack growth analysis for a defective rail.
Linear-Elastic and Elastoplastic Mode II and III Crack Tip Stress-Strain Fields in Cylindrical Specimens with Circumferential Crack
Authors: Horníková Jana , Šandera Pavel , Pokluda Jaroslav
Published: October 2009

A numerical analysis by means of the ANSYS code was performed in order to identify the ratio of both stress intensity factors and crack tip opening displacements for a cylindrical specimen with circumferential V-notch loaded by remote pure shear stress. This kind of loading produces pure mode II and III loading in four points on the circumferential crack front while the mix mode II+III exists in all other crack front points. In the linear-elastic range, the ratio of maximum values of mode III and mode II stress intensity factors was found to be . On the other hand, the ratio of crack tip opening displacements in the elastoplastic range approaches . These results can be used for the construction of fatigue crack growth rate curves in austenitic and ferritic steels measured in the near-threshold and near-fracture regions by means of a special testing device.
Investigating Sound Sources of Faulty Gear Units
Authors: Belsak Ales , Prezelj Jurij
Published: October 2009

In diagnostics, the condition of mechanical systems can be determined very reliably on the basis of noise. Noise source visualization is based on a number of different methods. These methods are primarily intended for a specific noise source in a specific acoustic environment. In this paper, a visualization method of complex noise sources, based on the use of acoustic camera, is dealt with. All types of different complex noise sources can be visualized, using a special acoustic algorithm. Also, various transient acoustical phenomena can be observed.
Experimental Evaluation of Corrosion Effect on Bond Between Steel and Concrete in Presence of Cyclic Action
Authors: Giordano Luca , Mancini Giuseppe , Tondolo Francesco
Published: October 2009

Corrosion modifies the steel-concrete interface in reinforced concrete structures. The efficiency of the connection between the two materials is reduced and the structural behavior both in service and in ultimate condition is affected. Moreover in structures subjected to cyclic load, a simultaneous mechanical deterioration due to the load is present. In this work an experimental analysis on reinforced concrete structures under both cyclic load and corrosion of reinforcing bars is presented. Three couples of reinforced concrete ties are connected in series and subjected to the same stress variation in order to produce the cracking conditions and to activate the bond mechanism. However, while one of the two reinforced concrete ties is only subjected to cyclic load, the second one is also corroded using an accelerated electrochemical corrosion process. The simultaneous effect of the cyclic load and corrosion is evaluated monitoring the crack opening on the structures during the test and by means of visual inspection of the sample. The test results show the correlation between the mechanism of bond and the average level of stresses for an amplified stress range.
Numerical Modeling of Ultrasonic Guided Waves for Damage Detection in Structures
Authors: Viola Erasmo , Marzani Alessandro
Published: October 2009

This work presents a numerical simulation of the behavior of stress guided waves (GWs) propagating in a multilayer system composed of porous materials. To this end, the damped Semi-analytical Finite Element (SFE) formulation proposed in [1] is extended to take the dry porosity into account. An application of waves propagating in two squared aluminum bars jointed by a weaker layer of porous adhesive is presented. Numerical results show that variations of the adhesive's porosity modify the GWs spectro-temporal patterns. These changes could be exploited to detect the level of adhesive porosity in a total nondestructive manner for the above structures.
Determination of Spring Constant for Simulating Deformable Object under Compression
Authors: Ko Koeng Wook , Kim Hyun Soo , Bae Sung In , Kim Eui Seok , Lee Yuan Shin
Published: October 2009

It is not easy to simulate realistic mechanical behaviors of elastically deformable objects with most existing mass-spring systems for their lack of simple and clear methods to determine spring constants considering material properties (e.g. Young's modulus, Poisson’s ratio). To overcome this obstacle, we suggest an alternative method to determine spring constants for mechanical simulation of deformable objects under compression. Using the expression derived from proposed method, it is possible to determine one and the same spring constant for a mass-spring model depending on Young's modulus, geometric dimensions and mesh resolutions of the 3-D model. Determination of one and the same spring constant for a mass-spring model in this way leads to simple implementation of the mass-spring system. To validate proposed methodology, static deformations (e.g. compressions and indentations) simulated with mass-spring models and FEM reference models are compared.
Effect of Shot Peening on Residual Stresses and Surface Work-Hardening in Cold Sprayed Coatings
Authors: Bagherifard Sara , Fernàndez Parienete Ines , Ghelichi Ramin , Guagliano Mario , Vezzù Simone
Published: October 2009

Coating deposition processes such as cold spraying are commonly employed to increase wear and fatigue resistance and consequently to enhance longevity of engineering components. Such processes typically introduce residual stresses into the coated surface, which in turn affect efficiency of coatings and play an important role in coating durability. Present study describes alteration of residual stress state and surface work-hardening of two types of aluminum coatings that are cold sprayed onto aluminum substrate, and subsequently treated by air blast shot peening (ABSP). Residual stress measurements have been made by means of X-ray diffractometer (XRD) on coated samples both before and after shot peening process. The results indicate that that the effect of shot peening is more marked in terms of surface work-hardening than of residual stresses and allow some consideration to correctly orient the choice of peening parameters in practical application.
Investigation on the Large Strain Elastoplastic Constitutive Model with Logarithmic Stress Rate Based on Torsion Experiments
Authors: Yang Li Hong , Zou Guang Ping , Yang Li Ping , Zhang Xue Yi
Published: October 2009

A complete analysis was made for an isotropic hardening rate-type elastoplastic constitutive model with the logarithmic stress rate utilizing solid shafts torsion test in the large strain range. The deformation rate, the logarithmic spin, the Kirchhoff stress and the logarithmic stress rate of the Kirchhoff stress were obtained for the free-end solid shaft torsion test when considering Swift effect. Utilizing the results obtained from the solid shaft torsion test, the plastic rigidity function in the isotropic hardening elastoplastic constitutive model was determined at finite strain range. It was shown that the influence of Swift effect on finite strain constitutive model was related to the varying rate of axial deformation and the varying rate of radius deformation to shear strain, and the plastic rigidity function corresponding to the logarithmic stress rate was the same as that corresponding to the Jaumann stress rate when neglecting Swift effect.

Solid shaft can achieve very large strain without buckling in torsion test. They can be used to accurately determine the large strain elastoplastic behavior [1-3]. Many researchers are interesting in the theoretical study and experimental study on large strain torsion deformation [1-7]. Jaumann objective stress rate is often adopted for study on constitutive models [1], but Nagtegaa J C [8] discovered that Jaumann stress rate may render oscillatory stress response for anisotropic kinematics hardening simple shear problem. After that, great interests focus on the issues of choosing an appropriate objective stress rate in rate type constitutive models. The expression of logarithmic stress rate with logarithmic spin can be found in Xiao H [9]. It had been proved that among all rate type elastoplastic constitutive models, only those with the newly discovered logarithmic stress rate fulfill the self-consistency criterion. In this paper, the parameter in large strain isotropic hardening elastoplastic constitutive model is determined with logarithmic rate of Kirchhoff stress utilizing solid shaft torsion test.
Evaluation Method for Time-Dependent Corrosion Behavior of Carbon Steel Plate Using Atmospheric Corrosion Monitoring Sensor
Authors: Kainuma Shigenobu , Sugitani Kunihiro , Ito Yoshihiro , Kim In Tae
Published: October 2009

The purpose of this research is to propose a method for evaluating the time-dependent corrosion behavior of carbon steel plates using an atmospheric corrosion monitor (ACM) corrosion sensor consisting of a Fe/Ag-galvanic couple. Atmospheric exposure tests were carried out on steel　plates for periods of 6, 12, and 24-months on the island of Okinawa in Japan. The Specimens were mounted on racks at angles of 0, 45 and 90 to the horizontal to obtain corrosion data in various corrosive environments. In addition, the environments of the skyward- and groundward-facing surfaces of the specimens were monitored using ACM sensors. The sensor outputs were recorded during the exposure tests.
Experimental Research on Dynamic Failure of Brittle Materials
Authors: Chen Jing Xi , Zhang Guang , Tan Hai Li , Du Zhen Dong
Published: October 2009

Dynamic failure of brittle materials is a rather complex issue. In this paper, experimental work was carried out for plaster model, to study the crack development features of brittle materials under the action of explosion. It shows that couple medium has great influences on detonation wave type. The water has the cushioning effect on detonation wave, which makes the wave crest truncated and results in low wave amplitude and large wave width. Detonation wave type has apparent influence on failure features of brittle materials, of which larger wave width would keep the wall of exploded hole intact and increase the development length of cracks. The research results would be applied to coal mining to increase the efficiency of gas pumping drainage.
Experiments and Strength Prediction of a Joint Composed of a Pultruded FRP Tube Bonded to an FRP Lamella
Authors: Hehl Simon , Vallée Till , Bai Yu
Published: October 2009

Adhesively bonded connections involving pultruded FRP typically fail in a brittle manner, making their analysis a case study for the application of statistical size effects. For brittle materials, in which failure is often caused by a single critical defect, statistically based size effects on strength are adequately explained by probabilistic theories such as the Weibull strength theory. A previously implemented probabilistic dimensioning method for adhesively bonded balanced joints is extended to a complex joint involving a tube and a lamella, both made of pultruded FRP. Instead of the previously used 2d approach the extension requires a 3d formulation. The entire joint is idealized as being constituted by n elements; its survival depends on the simultaneous survival of all elements. By the means of a 3d FEA, failure triggering stress components in all n elements were determined; a probability of failure is associated to each element using the corresponding combination stresses combined into an appropriate failure criterion, hence defining a theoretical joint strength.
Local Investigation of Microstructure-Induced Fatigue Damaging
Authors: Marx Michael , Schäf Wolfgang , Welsch Markus T. , Vehoff Horst
Published: October 2009

From the emission of dislocations till short crack propagation fatigue is a local process determined by the microstructure. In this paper we present experiments based on refined applications of the scanning electron microscope and focused ion beam technique, which give detailed information about crack initiation and the interaction of short fatigue cracks with microstructural elements.
Study of Risk Evaluation System of High Arch Dam Based on Failure Mechanism
Authors: Chen Zai Tie
Published: October 2009

In view of the randomness in terms of high arch dam load, resistance and failure calamity loss as well as the fuzziness in terms of evaluation conclusion, a high arch dam risk evaluation system is established by means of risk analysis method. Natural factors, structural factors and human factors that lead to high arch dam failure are summed up on the basis of statistics. Through qualitative analysis coupled with quantitative estimation, it is determined that high arch dams generally involve five major failure modes: abutment rock mass destabilization, excess cracking, arch dam & dam foundation entire destabilization, extreme dam-overflow and destabilization of dam body along base plane. The state functions of individual major failure modes are established. An approach is made to the correlativity among the major failure modes and among the random variables within individual failure modes, and it is suggested that risk rate, economic loss risk value and life loss risk value should be used to assess the risk of high arch dams. A certain high arch dam abutment instability risk evaluation has been provided.
Two Ways of Closing Cracks on Asphalt Concrete Pavements: Microcapsules and Induction Heating
Authors: Garcia Alvaro , Schlangen Erik , Van de Ven Martin
Published: October 2009

It is well known that asphalt concrete is a self healing material: immediately after both faces of a crack are in contact, the diffusion of molecules from one face to the other starts. If there are no more loads, this process takes place until the crack has completely disappeared and the material has recovered its original resistance [1]. To increase this healing rate two methods are proposed. The first one is a passive self-healing mechanism. Embedded encapsulated chemicals are used in the binder. When microcracks start appearing in the binder due to the combination of ageing and accumulated damage, they break the capsules and the chemicals enter the binder by diffusion. These chemicals repair the material, decreasing the stiffness and increasing the healing rates of bitumen. The second approach makes use of an active self healing mechanism. Local heating inside the material is used to repair the binder and to improve the properties again. This is realized by adding conductive particles to the binder and using induction energy to increase the temperature. These methods are a fairly new concept in the asphalt industry.
Cyclic Response and Fatigue Life of TiAl Alloys at High Temperatures
Authors: Kruml Tomáš , Obrtlík Karel , Petrenec Martin , Polák Jaroslav
Published: October 2009

Fatigue properties of the new generation of TiAl alloys with 8at.% of Nb were studied and compared with those reported in the literature for previous generation with 2at.% of Nb. The high Nb content improves substantially the fatigue life time in the Basquin representation. Nevertheless, the fracture behaviour is still rather brittle even at 750°C. TEM study of the material after the fatigue testing was performed. The dislocation activity is concentrated in the  phase. The properties and behaviour of individual dislocations seem to be similar as those observed in single -phase TiAl alloys.
Increasing Behavior of Strength for Fatigue Fracture of Austenitic Stainless Steel during Fatigue Tests at Elevated Temperature
Authors: Kanazawa Kenji , Sugimoto Maya
Published: October 2009

In order to clarify notch effect on fatigue strength of an austenitic stainless steel, rotating bending fatigue tests were carried out for smooth and notched specimens at 573K. Clear endurance limits were recognized and the fatigue strength did not decrease continuously with increasing stress concentration factor Kt, notwithstanding any non-propagating crack was not recognized at notch roots for specimens endured at 108 stress cycles. According to hardness tests, an area of notch root hardened during fatigue test by dynamic strain aging. The hardening behavior occurred remarkably with increasing Kt. Effects of Kt and the hardening behavior on fatigue strength canceled each other, and then fatigue strength became insensitive to Kt. Fatigue strength σSIT obtained by stress increment fatigue tests became higher than the ordinary fatigue strength for each specimen of Kt, that is, the coaxing effect was recognized clearly. This result indicated that the strength for fatigue fracture increased gradually during fatigue test. σSIT had a peak value at Kt of 2.0 and it decreased with increasing Kt sensitively. The increasing behavior of strength for fatigue fracture depended on Kt and fatigue fracture was controlled by circumstances of hardened material and stress amplitude considering Kt.
Experimental and Numerical Analysis of the Fatigue Behaviour of Panels Repaired by Patches in Composite Material
Authors: Ricci F. , Franco Francesco , Montefusco Nicola
Published: October 2009

In this paper, the mechanisms of propagation of the damage in aluminum panels repaired with bonded composite patches of different mechanical characteristics is analyzed. The aim of this study is to analyze analytically, experimentally and numerically the advantage of the use of bonded composite patches to increase the fatigue life and to reduce the state of tension at the crack tips. The experimental results show that both static strength and fatigue life of the repaired aluminum panel has significantly increased due to the bonded composite patches. The different patches and adhesive, used for cracked panels, have provided about a 100-110% improvement in the fatigue life and a 30-35% decrease in the stress intensity factor. A comparison between finite elements calculations and experimental data has been carried out. The good agreement between the experimental data and the numerical ones has demonstrated the possibility to obtain an optimized design of bonded patches with the numerical tools.
Do Notched Thick Plates Have Strength in Shear?
Authors: Harding Steven , Kotousov Andrei G.
Published: October 2009

This paper summarizes recent theoretical studies on the three-dimensional singular stress state at sharp notches in infinite (or large) plates of finite thickness subjected to in-plane loading. In general, such loading produces a number of singular states: in-plane singularities (normally described as KI and KII fracture modes and known as Williams’ solution), singular states associated with corners and the out-of-plane singularity (KO mode), which is generated due to the Poisson’s effect. The latter mode has an interesting behavior and its intensity increases as a power function with the increase of the plate thickness when the notch is stresses in shear mode. From finite fracture mechanics considerations it is clear that at some certain thickness the out-of-plane singular mode will dominate over the fracture zone and with the further increase of the plate thickness will affect the strength of the notched plate, virtually reducing it to zero.
Strength Response and Failure Analysis of Ceramic Alumina Tiles
Authors: Constantinescu Dan Mihai , Sandu Marin , Volceanov Eniko , Miron Matei Constantin , Apostol Dragos Alexandru
Published: October 2009

Static loading and impact tests of ceramic alumina tiles have shown a very interesting behaviour of tough, brittle, and high energy absorbing materials. Strain gauges techniques and data acquisition were used in previous research for static and low velocity impact testing. A static-dynamic equivalence was done through a calibration procedure of the measuring system. The research is continued in this paper by using the digital image correlation method with the complete displacement and strain history acquired till the failure of the ceramic tiles of different compositions, proving the capacity of such materials to be used for particular purpose applications.
Effects of Recycled Coarse Aggregates on the Carbonation Evolution of Concrete
Authors: Xiao Jian Zhuang , Lei Bin , Zhang Chuan Zeng
Published: October 2009

Concrete exposing to atmosphere suffers from changes in its internal structure, for instance loss of alkalinity of the cover concrete and corrosion of steel rebar due to carbonation, which in extreme cases affect the safety, the reliability and the durability or the service life of the structure. Carbonation is one of the key environmental actions that may cause structural failure. This study aims to gain some new information on the carbonation resistance when recycled coarse aggregates are used to mix new concrete. The concrete’s resistance to carbonation is determined by measuring the carbonation depth of 100mm×100mm×300mm concrete prisms in according to GBJ 82-85. Two series of tests including 9 groups of recycled aggregate concrete specimens are carried out, in which the effects of the quality and replacement of recycled coarse aggregates on the carbonation behavior of recycled concrete are evaluated. The essential test results are presented and discussed in this paper. Based on the findings of the present study, in order to reduce the unfavorable effects of recycled coarse aggregates on the recycled concrete, limiting the compressive strength grade of original concrete and the replacement of recycled coarse aggregate is a good option under the condition of using recycled concrete in considered projects.