bluuebunny/crossref_metadata_2025 huggingface dataset:
Properties of Cement Composite Containing Waste Tire Rubber, Silica Fume and Polypropylene Fiber
Authors: Sadrmomtazi Ali , Zanoosh Romina Zarshin
Published: September 2011

Management of solid wastes is one of the most important issues around the world. Vehicle tires are one of these solid wastes. A test program was carried out to determine the mechanical properties of rubberized concretes with and without silica fume and polypropylene fiber. The main objective of this study was to investigate the use of silica fume in cement composite containing waste rubber tire. In the present work the Silica fume was replaced by 10% of cement weight. Five designated rubber content varying from 10% to 50% by volume and polypropylene content 0.3% by volume were used. The 28-days properties of the cement composite were determined. The analyses included compressive strength, flexural strengths, velocity of ultrasonic wave, water absorption and Scaning electron microscopy(SEM). The results indicated the following points: Increase in rubber content decreases the sample unit weight, the introduction of rubber particles significantly increas the strain capacity of the materials and the use of silica fume increas the mechanical properties.
A Torus Patch Approximation Approach for Point Projection on Implicit Surfaces
Authors: Liu Xiao Ming , Yang Lei , Hu Qiang , Yong Jun Hai
Published: September 2011

Point projection on an implicit surface is essential for the geometric modeling and graphics applications of it. This paper presents a method for computing the principle curvatures and principle directions of an implicit surface. Using the principle curvatures and principle directions, we construct a torus patch to approximate the implicit surface locally. The torus patch is second order osculating to the implicit surface. By taking advantage of the approximation torus patch, this paper develops a second order geometric iterative algorithm for point projection on the implicit surface. Experiments illustrate the efficiency and less dependency on initial values of our algorithm.
A Component-Based Meta Modeling Framework for Complex Product Virtual Prototype
Authors: Li Tan , Lin Ting Yu , Chai Xu Dong , Hou Bao Cun
Published: September 2011

Effective reuse and integration of multidiscipline model resources is a key issue and challenge in the Virtual Prototyping for Complex Products. Based on the Meta Object Facility and Component-based Modeling, This paper proposes a new component-based Meta Modeling Framework (M2F) of Complex Product Virtual Prototyping as a solution, providing the model specifications for each abstract layer (CAP model, CIM model and High-level model) in the framework. M2F enables multi-layered abstraction of those isomerism models in Complex Product Virtual Prototype and facilitates the unified modeling, reuse and integration of models. A case study about typical complex product indicates this approach not only makes the system-level modeling of virtual prototype easy, but also improves the reusability of component models. At the end of this paper, conclusion and future works are given.
Filling Quality of Ammunition Production and Jet Motion in Defective Filling
Authors: Dong Su Rong , Chen Guo Guang
Published: September 2011

The major defects in ammunition production and the production process of liner are discussed. The propagation mechanism of detonation wave in defective filling as well as energy density of detonation wave the influence on jet motion is studied in this paper. Through the experiment of liner, the law of jet motion in defective filling is simulated. The simulation result shows that deviation of the jet motion trajectory would reduce the power of anti-armor.
Parameterized Modeling of Parts Based on SolidWorks
Authors: Yan Xiang Tong
Published: September 2011

According to the analysis of CAD technology and Solid Works software, the design idea and methodology of 3D modeling and parameterized design are put forward based on Solid Works, and the example of shearer drum model is used to introduce the modeling process in detail. The method will shorten the design time，increase the quality of design and provide useful help to quickly design of mechanical product.
Numerical Simulation of Erosion and Particle Motion of Multi-Medium Oil-Coal-Water Slurry Pump
Authors: Zhang Qiang , Song Qiu Shuang , Mao Jun
Published: September 2011

Oil-coal-water slurry as a new alternative fuel was used on diesel engines. The Multi- medium oil -coal-water slurry pump wears serious bottleneck with presence of solid coal particles. Based on VOF multi-flow model, Reynolds stress model and discrete phase model to the continuous phase and dispersed phase, the Multi- medium erosion and motion trajectory of solid particle the impact progress between solid particle and machine surface were simulated successfully. The volume content of solid phase in Multi- medium flow was lower than 10 % in this simulation model. According to the simulation result, the related parameters of solid particle, such as density and diameter, mix proportional and plunger speed of impeller greatly influenced the motion trajectory and the impaction with machine surface of solid particle. The solid particle with large mass was apt to move toward to the working surface and impacted the inside of piston shell. By contraries, little particle was liable to impact the plunger barrel assembly. The plunger speed more high, the plunger barrel assembly more erosion. The plunger barrel assembly wears with solid mix proportional.
A Parametric CNC Programming Method for Rapid Battlefield ManufacturingF
Authors: Zhang Zhi Jing , Zhang Shao Hua , Zhang Jian Cheng , Jin Xin , Liu Bing Bing
Published: September 2011

This paper presents a method for the battlefield manufacturing to make the NC codes programming easier and quicker for knowing little about NC codes programming. To implement the method the dynamic link library (DLL) has been programmed in Microsoft® Visual C++ as a functional module, which is embed in HNC-21. The experiments have been made to validate the method can generate the correct NC codes easily and quickly, and the codes can run exactly and well in HNC-21 to actuate the machine tool mounted HNC-21 to manufacture the qualified parts, finally the method is proved to give the powerful supporting to the military maintenance, especially for the maintenance in the battlefield, which needs better method to accomplish the manufacturing and maintenance quickly and accurately.
Knowledge Based Collaborative Modeling and Simulation Platform to Design Complex Product
Authors: Shen Dong Kai , Yan Zhao Bin
Published: September 2011

To complex system, its performance is related to many disciplines nowadays. This article proposed a new multidisciplinary collaborative modeling and simulation platform (MCMSP) in designing complex product. The platform is knowledge based so earlier design results and model can help new designers to shorten the development cycle. Then the author uses this platform to design Electro hydrostatic actuator (EHA) which is widely used in Power-By-Wire (PBW) system.
Study on Practical FBG Acceleration System
Authors: Zhang Wei Guang , Zhang Jian
Published: September 2011

A micro vibration, high sensitivity FBG demodulation system with close loop control is presented. By introducing a close loop control, the difficulty in matched FBG making process is overcame. Further more, the FBG strain-temperature cross sensitivity problem is settled. And low sensitivity in high frequency of cantilever FBG accelerator is overcame either. An example of the system application in acceleration measurement is introduced.
Research of Pelvimetry Based on Electromagnetic Tracker
Authors: Lu Yao Sheng , Wang Wen Bo , Huang Yao Xiong
Published: September 2011

Traditional pelvimetry for a pregnant women is mainly relied on a ruler or estimation based on the vaginal touch, which results a very high measuring error. A new pelvimetry based on electromagnetic tracker is proposed in this paper , and a measure system has been developed . It’s a non-invasive method to measure key parameters of a pelvis because of the character of high accuracy, without line-of-sight restrictions and non-radiation of electromagnetic tracking technology. Its precise measuring data can well fulfill clinical pelvimetry needs, and be helpful for a physician to make decisions to go on a vaginal delivery or not during a labor.
Innovative Siloxane Coating Formulations: The Experimental Assessment of the Durability of Colour
Authors: Alaimo G. , Enea D. , Nuccio E.
Published: September 2011

Maintenance programming of civil and industrial buildings is a relevant problem, especially in a global situation where natural resources are increasingly limited. Accurately knowing the durability of building products and components, essential for a sustainable use of resources, becomes more and more important after the recent 18 January 2011 resolution of the European Parliament, which introduced the seventh requirement on construction products, specifically regarding the sustainability and therefore the durability of such. This study concerns the evaluation of the durability of some innovative coatings based on acrylic-siloxane resins containing several pigments, used for building external decorative finishing, applied in thin thickness and of different basic components. The parameters investigated are: the surface appearance and the maintenance of the original colour, significant for the aesthetic quality of the architecture. The paper presents the first results of the experimental study on coating materials, produced by Hydrate Ltd, performed according to ISO 15686, aimed at defining the Reference Service Life, by monitoring the behaviour over time of artificially aged samples in the climatic chamber and external exposed samples, as well as the monitoring of a case study.
Numerical Investigations of Ultrasonic Scattering from Voids in Composite Materials Based on Random Void Model
Authors: Lin Li , Zhang Xiang , Chen Jun , Li Xi Meng
Published: September 2011

Ultrasonic attenuation coefficient is firstly calculated utilizing the finite difference time domain method based on a novel 2-D RVM for carbon fiber reinforced plastic (CFRP) composite materials. The results show that the void morphology has detrimental effect on ultrasonic attenuation. Even at the fixed porosity, ultrasonic attenuation coefficient fluctuates due to the randomness of void morphology in CFRP composite materials. This work significantly helps to understand ultrasonic scattering mechanism of voids and formulation of CFRP composite material properties.
Backlash Compensation on CNC Machine Tool Based on Semi-Closed Loop Control
Authors: Feng Bin , Mei Xue Song , Guo Liang , Zhang Dong Sheng , Cheng You Long
Published: September 2011

The positional accuracy and machining precision are mainly affected by backlash for semi-closed loop control CNC machine tool. And compensation for backlash is essential to improving the accuracy of machine tool. A method is developed to reduce contouring error in this paper. A simulated model of backlash and Open CNC system are used to verify compensation algorithm. Computational simulations and experimental results have shown that the contouring error due to backlash can be greatly reduced by using backlash compensation.
Wavelet Analysis on Nonstationary Random Road Irregularities
Authors: Hu Zhi Gang , Chen Li Ping , Zhang Yong Lin , Song Shao Yun , Guo Wei Feng
Published: September 2011

By using time domain modeling obtained from PSD for stationary random road irregularities, concerning about non-uniform moving-vehicle conditions and non-stationary road characteristics, via model assembly and integration to generate non-stationary random road time domain modeling for inputting road excitation. On the assembly of the non-stationary random road time domain modeling, Time-Frequency was analyzed via wavelet analysis. From road data decomposed by the way of Wavelet, both time domain characteristics of signal components in different bands can be obtained and anomaly contained within the signal can also have accurately time-frequency localization. The signal separation can help achieving non-stationary sub-band analysis, and can further study the affection of road signal in different band focus on vibration response of the vehicle, and also providing a strong theoretical basis for road design, quality inspection and grading.
An Efficient Image-Based Method for Detection of Fastener on Railway
Authors: Yang Jin Feng , Liu Man Hua , Zhao Hui , Tao Wei
Published: September 2011

This paper presents an efficient method to detect the fastener based on the technologies of image processing and optical detection. As feature descriptor, the Direction Field of fastener image is computed for template matching. This fastener detection method can be used to determine the status of fastener on the corresponding track, i.e., whether the fastener is on the track or missing. Experimental results are presented to show that the proposed method is computation efficiency and is robust for fastener detection in complex environment.
Low-Cost Fastener Inspection System on High-Speed Railway
Authors: Zhang Hai Bo , Yang Jin Feng , Zhao Hui , Liu Man Hua , Tao Wei
Published: September 2011

The demand for the high-speed fastener inspection technology has increased greatly as the train speed is growing up. A low-cost high-speed fastener inspection system was proposed in this paper. By using motion image and direction field, the proposed inspection system takes some advantages of current methods, and has the features of depth insensitive and high contrast with background.Our experimental results show that this system is a potential solution for high-speed fastener inspection.
Application of Wavelet Analysis in Transient Electromagnetic Sounding
Authors: Tang Jun
Published: September 2011

On the basis of explaining the basis theory on transient electromagnetic sounding, wavelet theory and imaging principle of differential conductivity for transient electromagnetic sounding data, this thesis proposes rapid imaging technology of electromagnetic sounding based on wavelet analysis, describes the characteristics of noises under wavelet decomposition, and employs wavelet packet analysis to eliminate noise of signals, at last, introduces wavelet analysis into transient electromagnetic sounding on the platform of MATLAB wavelet function toolbox and deals with differential conductivity imaging processing steps of transient electromagnetic sounding.
Design on Hierarchical Testing System for Unmanned Ground Vehicles
Authors: Li Xin , Xiong Guang Ming , Sun Yang , Wu Shao Bin , Gong Jian Wei , Chen Hui Yan , Gao Li
Published: September 2011

The test system for technical abilities of unmanned vehicles is gradually developed from the single test to comprehensive test. The pre-established test and evaluation system can promote the development of unmanned ground vehicles. The 2009 Future Challenge: Intelligent Vehicles and Beyond (FC’09) pushed China's unmanned vehicles out of laboratories. This paper proposed to design a more scientific and comprehensive test system for future competitions to better guide and regulate the development of China's unmanned vehicles. According to the design idea of stage by stage and level by level, the hierarchical test content from simple to advanced, from local to overall is designed. Then the hierarchic test environment is established according to the levels of test content. The test method based on multi-platform and multi-sensor is put forward to ensure the accuracy of test results. The testing criterion framework is set up to regulate future unmanned vehicle contests and to assess the unmanned vehicles scientifically and accurately.
Generation of the 3D CAD Model of Construction Building
Authors: Li Xiao Yong , Zhang Zhi Gang
Published: September 2011

Project teams face ever increasing pressure to deliver projects as quickly as possible. To meet these demands, contractors are faced with the need to explore various construction strategies in order to meet delivery dates, and to assure themselves as to the achievability and quality of construction building. Various visual representations of construction building, i.e. 3D CAD, can assist with these tasks of identifying effective construction program. Such visual representations aid communication amongst project staff and facilitate brain-storming, and, implemented well they can provide clear, fast, and multi-dimensional feedback to the project team. In this paper, we describe aspects of our work which is directed at formulating a dynamic visualization environment that links 3D CAD. Requirements of such an environment include quickness, treating scale, working at multiple levels of detail, dealing with design variability, and realistic representation of the work. The applicability of the system is demonstrated by applying it to various examples. The results show that the system can be effectively used for generating the 3D CAD model of construction building.
Application of Multi-Baseline Digital Close-Range Photogrametry Technique in 3D Reconstruction of Underground Tomb
Authors: Wu Xing , Feng Wei , Wang Kai
Published: September 2011

The theory and characteristics of the multi-baseline digital close-range photogrametry were discussed to be used in cultural relics preservation. Take the 3D reconstruction project of the Yu Shan the 5th mural tomb in Ji-an as an example, two methods were put forward to measure the control points of the image without any harm to the object. Also, Tricolor cool tone electron energy conservation lamp was used to meet the strict color control of the mural images. Engineering tests show that the methods put forward could greatly reduce the field work and labor intensity with the characteristics of high accuracy, automation and efficiency. Production efficiency is improved as well. The precision of mapping and image texture satisfies the requirements of cultural relics preservation. In addition, how to manage and index such data through database technology needs further study.
Load’s Damping Swing by Trolley’s Driving Force Control for Overhead or Gantry Crane
Authors: Zhong Bin , Zhan Ren Jun
Published: September 2011

In order to obtain the trolley-load system’s dynamic equations for overhead crane or gantry crane, analyzed the dynamic system and deduced the transfer function between the load’s sway angle and the force acting on the trolley from dynamic equations. The force control mode for load’s damping swing is an effective measure of compensation for active anti-swing. Dynamic simulation results show that the optimal evacuation time of the force acting on the trolley is a key parameter that affects the damping swing’s effect. The load’s damping swing effect is favorable when the driving force is withdrawn at optimal withdrawing time; the load’s swing angle’s amplitude will increase with driving force’s increase, but the damping swing effect is still favorable if the optimal withdrawing time is favorably controlled.
Aerodynamic Performance of a Double-H Type Vertical-Axis Wind Turbine: Designed by a Stream-Tube and CFD Method
Authors: Jiang Jin , Zheng Xiong Bo , Zhang Liang , Li Zhi Chuan , He Li
Published: September 2011

The thesis improves a stream-tube method based on solidity modification and CFD method used to predict both steady and unsteady aerodynamic performance of the fixed-pitch vertical-axis with double straight-blades type of turbine designed by FengFa Technology for wind conversion. Numerical results of predicting instantaneous blades forces and power output of the rotor showed good agreement with the test data, which showed that the present model is suitable for the design and optimization of such kind of turbine.
Performance of Different Metal-Foam Stuffed Whipple Shield against Hypervelocity Impact of Space Debris
Authors: Jia Bin , Li Feng , Gong Hai Peng , Pang Bao Jun
Published: September 2011

Hypervelocity impacts on spacecraft in low earth orbit by meteoroids and space debris poses a threat to space missions, and the use of a shield can significantly decrease the probability of a catastrophic failure. Tests have identified that metallic foams have a good shielding performance against hypervelocity impact by micro-meteoroids and orbital debris. A metal-foam stuffed Whipple shield was presented under the concept of light-weight shield structure. A meso-structure model of geometry for metallic foams was set up simulating their manufacturing process and validated by comparison with experimental results using own SPH code. Three base materials of foam, including Al 7075-T651, Ti and Al ZL102, were researched for their performances as stuff of shield by means of numerical simulation. The results indicated that different base materials show the best shield performance at different impact speeds with other conditions the same. The foam of Al ZL102 stuffed can cause the strongest radial dispersion of the secondary debris cloud and is more likely to provide the best shield performance, which is proved at the higher part of the speed range investigated.
Modeling Fracture of Fiber Reinforced Polymer
Authors: Ožbolt Joško , Lacković Vesna , Krolo Joško
Published: September 2011

In the present paper 3D rate sensitive constitutive model for modeling of laminate composites is presented. The model is formulated within the framework of continuum mechanics based on the principles of irreversible thermodynamics. The matrix (polymer) is modeled using 3D rate sensitive microplane model. For modeling of fibers (glass) a uni-axial constitutive law is employed. The fibers are assumed to be uniformly smeared-out over the matrix. The formulation is based on the assumption of strain compatibility between matrix and fibers. To account for the de-lamination of fibers, the matrix is represented by the periodically distributed bands with non-uniform strength properties over the band width. The input parameters of the model are defined by the mechanical properties of matrix and fibers (elastic properties, strength and fracture energy), the volume content of fibers and by their orientation in 3D space. The model is implemented into a 3D finite element code. To assure mesh objective results, the localization limiter is based on the assumption of constant energy dissipation within each finite element, i.e. the crack band method is used. The performance of the model is shown on one numerical example for specimens loaded in uni-axial tension. It is demonstrated that the proposed model is able to realistically predict the resistance and failure mode of complex fiber-reinforced composite for different orientation of fibers.
Effect of Notched Parameters on Low Cycle Fatigue Life of Shaft under Bending-Torsional Loading
Authors: Ma Ping , Li You Tang
Published: September 2011

A special clamp for fatigue of shaft under bending-torsion that used on the fatigue machine is designed and manufactured. For the medium carbon steel, the low-cycle fatigue experiments of shaft with annular notch under bending-torsion have been made on Shimadzu EHF-EM100kN high-frequency electro-hydraulic fatigue testing machine. Through experiments and analysis, the effects of tip radius, depth and open angle of notch on low cycle fatigue life of shaft with annular notch under bending-torsion are obtained. The method and results will play an important role on the fatigue life prediction and anti-fatigue design.
Investigation of Eigen-Values for Matrix Cracks of Two Materials
Authors: Li You Tang , Wang Rui Feng
Published: September 2011

The eigen-values problem of matrix cracks is studied in this paper. The stress field and displacement field of plane matrix crack is setup at first. The eigen-equation of matrix cracks is founded on the basis of the stress field and displacement field. The factors to affect the eigen-values are discussed. The effect of shearing modulus and Poisson ratio of matrix material and attaching material on eigen-values are analyzed. The results show that the bigger shearing modulus of material should be selected for attaching material and the shearing modulus of attaching material should bigger than that of matrix material in fracture design.
Fatigue Crack Shape Prediction Based on the Stress Singularity Exponent
Authors: Hutař Pavel , Ševčík Martin , Náhlík Luboš , Knésl Zdeněk
Published: September 2011

In many industrial applications it is necessary to predict fatigue lifetime of the structures where the stress field near the crack front have a three-dimensional nature. Due to the existence of vertex singularity in the point where the crack front touches free surface, crack propagation in 3D structures cannot be reduced to a series of plane strain or plane stress problems along the crack front. The paper describes the influence of the vertex singularity on crack shape for three-dimensional structure. The iterative process for estimation of a real crack front based on a stress singularity exponent is presented. In each node defining the crack front the stress singularity exponent has been estimated and complete crack front shape corresponding to the constant stress singularity exponent was found. The methodology presented can help to estimate crack front shape in a linear elastic fracture mechanics framework and estimate fracture parameters of fatigue cracks more accurately.
Fully Reversed Uniaxial Tension-Compression High Cycle Fatigue Behaviour of Shot-Peened Steels
Authors: Plumtree Alan , Mirzazadeh M. M.
Published: September 2011

The effect of shot-peening on the uniaxial fatigue behaviour of four engineering steels, heat treated to a similar final hardness was investigated. Forged 0.39%C and 0.72%C steels, a quenched and tempered 0.51%C steel and a 0.50%C powder forged (PF) steel were fatigue tested under fully reversed (R=-1) push-pull loading conditions. Following long life (107) cycling, shot-peening had little effect on the fatigue limit of the 0.39%C and 0.72%C steels whereas the fatigue limit of the PF steel increased 10.4%. Conversely, the fatigue limit of the quenched and tempered steel decreased 12.0% after shot-peening. The results showed that the beneficial effects of shot-peening, such as compressive residual stresses and work hardening, balanced the effects of surface roughness since crack initiation tended to occur below the surface. Microhardness profiles showed that the greatest amount of cyclic softening in the shot-peened regions occurred in the hot rolled steels. Softening was accompanied by a decrease in the depth of surface hardness.
Fatigue Strength of Radical Nitrided Spheroidal Graphite Cast Iron
Authors: Morino Kazuhiro , Nishimura Fumihito , Kawagoishi Norio
Published: September 2011

In order to investigate the effect of radical nitriding on fatigue strength of spheroidal graphite cast iron FCD400, rotating bending fatigue tests were carried out at room temperature. Fatigue strength was increased by nitriding. Fracture started from microshrinkages or abnormal graphites in the same manner as that of as cast iron. However, fracture mode was different according to the stress level. That is, fracture occurred from specimen surface at high stress levels and it occurred from defects in subsurface at low stress levels. The cause of these results was the hardened layer and the compressive residual stress, which suppressed the initiation of the surface crack.
MIC Behavior of the Low Alloy Steel with Different Zn-Epoxy Coating in SRB Solution
Authors: Wang Jun , Li Qing Fen , Fu Yu Dong , Li Chun Hui
Published: September 2011

The microbiological influenced corrosion (MIC) behavior of the low alloy steel with granular-Zn-epoxy and flaky-Zn-epoxy coating in the sulfate-reducing bacteria (SRB) solution was investigated with electrochemical impedance spectroscopy (EIS), X-rays diffraction (XRD), scanning electron microscope (SEM) etc. Results show that the protection effect of the flaky-Zn coating specimen is much better than the granular-Zn coating one. The dissolution of zinc is more severe in granular-Zn coating than in flaky-Zn coating when the specimen immersed in the SRB solution. The shielding property of flaky zinc is much higher than granular zinc in the coating. The flaky-Zn coating is much more compact than the granular-Zn coating and therefore the property of anti-infiltration is much better. We may conclude that the flaky-Zn coating exhibited more favorable corrosion resistance property than the granular one.
Strength Enhancement of Bottom Ash-Based Polymer Concretes
Authors: Zhao J. M. , Yang Z. X. , Hwang Kyu Hong , Lee J.K. , Kim M. C. , Seo G.D.
Published: September 2011

To replace bottom ash for natural sand completely, the mix proportions of bottom ash in concrete was adjusted according to tab density and replacement ratio of polymeric resin/Potland cement(PC) were established. And then testing for slump, setting time, and compressive strength was conducted. According to test results, the compressive strength of concrete using the bottom ash was lower than that of concrete using natural sand (BA0 concrete). But by adjusting the amount of bottom ash in concrete according tab density so that the fine aggregate proportions change 44% to 38%, the compressive strength of concrete using the bottom ash could even be higher than BA0 concrete. And as the polymeric resin content of bottom ash concrete increased, strength would be increased drastically, but proper dispersant should be cooperated with polymeric resin cement with fine bottom ash powders.
Slow Crack Growth and Creep Rupture of Ba0.5Sr0.5Co0.8Fe0.2O3 – δ
Authors: Malzbender Jürgen , Pećanac G. , Baumann Stefan
Published: September 2011

Ba0.5Sr0.5Co0.8Fe0.2O3 – δ is a mixed ion-electron conductor with high application potential as high-temperature gas separation membrane. However, in practical use the integrity of this brittle perovskite is challenged by the mechanical boundary conditions of transient temperature exposure. Moreover, long term failure mechanisms such as static fatigue at room temperature and creep rupture at operation temperature might occur. The relevance of both effects for BSCF has been investigated. The slow crack growth at room temperature has been determined using bi-axial bending under different loading rates. The creep rupture at elevated temperature has been analyzed from three-point bending tests. The results indicate favourable behaviour of BSCF in both cases. A low risk of failure due to slow crack growth exists and the strain to failure in combined tensile - compressive mode reaches up to 40 %.
Loading Frequency Effects on the Fatigue Crack Growth Rate and Fracture Surface Morphology of Low Carbon Steel in Case of Long-Term Use in Hydrogen Gas
Authors: Nishimoto A. , Oda Yasuji , Noguchi Hiroshi
Published: September 2011

Loading frequency effects on FCGR and fracture surface morphology were investigated on pre-strained low carbon steel in high FCGR range. Loading frequency effects showed the different trend between internal hydrogen and environmental hydrogen. The effects of combined condition hydrogen revealed similar tendency of environmental hydrogen.
Calibration of Constitutive Law and Ductile Failure Criterion for Very Thin Rectangular Al2024-T3 Aluminum Alloy Specimen
Authors: Giglio Marco , Gilioli Andrea , Manes Andrea
Published: September 2011

Thin plate structures are common in many industrial products and in particular they can be found as skins in sandwich panels. In order to develop complex FE analysis which involve the damage of these structures, it’s crucial the knowledge of constitutive law and damage criterion of the material they are made. In this paper a complete characterization of both constitutive material law and damage criterion for very thin rectangular Al2024-T3 aluminum alloy specimen plate has been done. The specimens have been cut, using a water jet machine, directly from sandwich panel skins in order to take into account the modification of mechanical behavior due to the manufacturing process. A complete experimental campaign of tensile tests has been done and an accurate virtual testing methodology has been subsequently applied (by means on Finite Element Models) in order to numerically reproduce the tests. The calibration of a fitted constitutive law and of three ductile failure criteria allows the numerical model to reproduce the experimental tests with good agreement up to failure.
Shaking Table Experimental Study on Damage Mechanism of the Disconnecting Switch under Seismic Excitation
Authors: Dembowski Paweł , Jankowski Robert
Published: September 2011

The efficiency of the energetic network is a very import safety issue in the region experienced by the earthquake. High voltage disconnecting switches are important elements of the energetic infrastructure used to separate electric circuits (i.e. during repairs), which should not be damaged remaining fully operational. The aim of the paper is to show the results of the shaking table experimental investigation focused on damage mechanism of a high voltage disconnecting switch under seismic excitation. The real example of the two-column pantograph-type disconnecting switch was considered in the study. First, the tests were carried out by exciting the unit with the sweep-sine function. Based on the results, the structural dynamic properties of undamaged structure (natural frequencies, damping ratios) could be determined. Then, the so called rumbling seismic tests were conducted in order to determine the seismic strength of disconnecting switch according to the standards PN-EN 60068-3-3. After each experiment, the sweep-sine test was carried out so as to check the decrease in the natural frequencies of the unit. The results of the study show that the lower parts of the columns, which serve as isolators, are the most critical locations of the disconnecting switch considered. The unit was damaged due to failure of one of the rotational mechanisms installed at the bottom of columns.
Bone-Cement Interface Micromechanical Model under Cyclic Loading
Authors: Sanz-Herrera J.A. , Esteban H. , Ariza M.P.
Published: September 2011

Total hip replacement is one of the most common techniques in orthopaedic surgery, and one of the most important surgical advances of the last XX century. Normally, implant is fixed to bone by means of a polymer material known as bone cement, building an interface between implant and bone regions. Microscopically, two interfaces can be distinguished, namely, bone-cement and implant-cement interfaces. One of the main causes of failure is implant loosening due to fatigue of one of the two microscopic interfaces. In this work, a micromechanical analysis of bone-cement interface under cyclic forces is introduced. Both bone and cement are considered using different models based on fatigue damage over a statistically representative volume element (RVE) of the microstructure. This technique allows to homogenize mechanical stresses of the RVE yielding the effective macroscopic behavior of the bone-cement interface, avoiding experimental fitting case to case, once the interface geometry and mechanical characterization of the involved phases are known.
Influence of Boundary Conditions on Higher Order Terms of Near-Crack-Tip Stress Field in a WST Specimen
Authors: Veselý Václav , Šestáková Lucie , Seitl Stanislav
Published: September 2011

A precise description of the stress and deformation fields in a cracked body is provided using multi-parameter fracture mechanics based on the approximation of the fields by means of the Williams’ power series. This paper presents a detailed analysis of the stress field in a wedge-splitting test geometry specimen aimed at the calculation of coefficients of the higher order terms (up to 14) of the Williams’ expansion. The numerical study is conducted with the use of a conventional finite element package; however, for processing of the results an over-deterministic method is employed. Special attention is paid to the influence of boundary conditions of the test geometry on the values of the coefficients of the higher order terms of the Williams’ series. The results are compared to data from the literature; a strong effect of the boundary conditions is observed.
Interaction of SH-Wave on Multiple Linear Cracks near Shallow-Embedded Structure
Authors: Yang Zai Lin , Xu Hua Nan , Xu Mei Juan , Sun Bai Tao
Published: September 2011

The surface displacement of a circular lining structure and multiple cracks in an elastic half space by incident SH-wave is studied in this paper based on the methods of Green's function, complex function and multi-polar coordinates. Firstly, we construct a suitable Green’s function which indicates a fundamental solution to the displacement field for an elastic half space possessing a circular lining structure and cracks while bearing out-plane harmonic line loads at arbitrary point. Then using the method of crack-division, a crack is created. Thus expressions of displacement and stress field are established at the existence of the structure and the cracks. Finally, the interaction of inclusion and two cracks is chosen as numerical examples and the influences of different parameters on the surface displacement are discussed.
Fatigue Growth Models for Multiple Long Cracks in Plates under Cyclic Tension Based on ΔKI, ΔJ-Integral and ΔCTOD Parameter
Authors: Božić Željko , Schmauder Siegfried , Mlikota Marijo
Published: September 2011

This paper presents the implementation of fatigue crack growth power law equations based on ΔK, ΔJ-integral and ΔCTOD fracture mechanics parameters determined in an FE analysis, to plates with multiple site damage (MSD). Results of fatigue tests with constant amplitude tensile loading carried out on mild steel plate specimens damaged with a single central crack and with three collinear cracks are presented. A relatively larger plastic zone occurred in the crack tip region at higher fatigue crack growth rate (FCGR), from 10-7 to 10-6 m/cycle. The crack growth models based on the elastic-plastic fracture mechanics (EPFM) parameters describe better fatigue crack growth in this range as compared to the liner elastic models.
Finite Element Simulation on Failure Assessment of Toughened Epoxy Adhesives
Authors: Akbarzadeh P. , Farhangdoost Khalil
Published: September 2011

The prediction of the strength of adhesively bonded joints has been investigated using a variety of failure criteria such as maximum stress or strain, and fracture mechanics approaches. Fracture mechanics approaches based on the critical strain energy release rate, for crack propagation are applicable to highly cross-linked structural adhesives and have the advantage of avoiding the explicit consideration of the bi-material singularities inherent in adhesive joints. In the present work, the finite-element simulation of such adhesive joint has been performed and the R-curves of two different rubber-toughened epoxy adhesives were measured using double cantilever beam (DCB) specimens. The FE results are applied to be compared with the experimental results which were reported in the literature.
API J55 Steel Casing Pipe with an Initial Surface Crack under Internal Pressure - Determination of Fracture Parameters
Authors: Rakin Marko , Medjo B. , Arsić Miodrag , Šarkoćević Ž. , Ivanović I. , Sedmak Aleksandar
Published: September 2011

Seam casing pipe used in an oil drilling rig, manufactured by high frequency (HF) contact welding of API J55 steel, is tested. The influence of an initial defect (machined surface crack) is analysed, by performing pressure test of a pipe segment closed at both ends. Besides the damages at the internal surface, casing pipes are exposed to damage at the external surface, which is why such configuration is analysed here. Measurement of strains and crack mouth opening displacement (CMOD) enabled the application of direct method for J integral evaluation. This procedure is based on the path independence of the J integral and can be applied both in laboratory conditions (on specimens) and on structures. However, it requires a demanding experimental - computational procedure, which is accomplished here using the developed routine. Additionally, the behaviour of the pipe under internal pressure, including fracture mechanics parameters determination, is modelled numerically (by finite element method) in software package Abaqus. The pressure is applied as distributed load acting on the inner surface of the three-dimensional model, and axial tension is applied at the end of the pipe to simulate the closed end. J integral values determined numerically and using direct method are used for estimation of the critical pressure corresponding to the crack growth initiation. Additionally, plastic limit load, i.e. pressure which causes yielding of the ligament, is determined. Based on the results, criteria for pipe integrity assessment are discussed
Influence of the Secondary Raw Materials on the Mechanical Properties of Multilayer Films
Authors: Didžiokas Rimantas , Janutėnienė Jolanta , Gintalas Marius , Tadzijevas A.
Published: September 2011

Recycling and usage of secondary raw materials in production is one of the most topical issues. Usage of secondary raw materials is one of the most topical issues in both economic and ecological (environmental) sense. Such a layered film on the market has lower price because secondary raw material prices is significant lower compared with the original material, the PET granules. Currently producing a layered film the middle layer composes up to 50 % of recycled material. In today's market in order to maintain a high level of competitiveness usage of 50 % of recycled materials is inadequate, therefore to use more recycled material amount and in such way to reduce product cost further researches are necessary.
The Effect of Lamb Wave Interaction with Fatigue Crack in Thin Al Sheet
Authors: Pavelko Vitalijs , Pavelko Igors , Ozolinsh Eriks
Published: September 2011

The phenomenon of the Lamb wave interaction with fatigue crack in Al2024-T3 sheet was investigated at cyclic loading. Mentioned effect is associated with the crack open/close that change acoustic impedance of a crack. Analytical simulation of fatigue crack opening using the generalized Dugdale’s model of a crack in thin plate shows good accordance between the intensity of ultrasonic signal and a crack opening.
High Rate and High Temperature Fracture Behaviour of Polycrystalline Diamond
Authors: Petrović Marin , Ivanković Alojz , Murphy Neal
Published: September 2011

Polycrystalline diamond (PCD) materials have a variety of applications, mainly as cutting tools for machining non-ferrous metals and non-metallic materials. A significant application of PCD is in oil and gas industry for rock drilling operations. Other important areas, such as mining, have yet to reach their full potential. These cutters/tools are subjected to high operating temperatures, impact loads and abrasive wear during these operations, which may lead to their sudden failure. An advantage of these materials is that their structure and composition can be engineered to return properties required for specific applications and operations.
Structural Analysis of Historic Masonry Arch Bridges: Case Study of Clemente Bridge on Savio River
Authors: Nobile Lucio , Bartolomeo Veronica , Bonagura Mario
Published: September 2011

The Clemente Bridge is a multi-span masonry arch bridge built during the 18th century on Savio River in Cesena. The aim of this paper is to assess its static capacity under live loads prescribed by Italian Standards in force. The analysis is performed employing RING 3.0, a computational tool based on Limit State Analysis. This method allows to individuate the minimum adequacy factor, that is the multiplier on vehicle loads required to cause collapse. In this way, a first assessment on the bridge safety can be obtained.
Explosion and Temperature Resistance of Underground Structures by Free Hexagons
Authors: Prochazka Petr P. , Lok Tat S.
Published: September 2011

It appears that sudden change of loading such as shock wave impinging on underground structures, which is mostly linked up with an extreme increase of temperature, causes immense disasters, which involve loss of human lives, heavy machine damage, long-lasting traffic troubles, decreasing of bearing capacity of the structural system, etc. A combination of shock wave due to both the elevated temperature accompanying explosion leads to cracking of the bearing system of underground openings, for example to cracking of concrete lining, i.e. to reduction of thickness of the bearing structures, etc. It has been previously proved that the free hexagon method serves for identifying the damage in the bearing system of underground structures very well. The dynamical influences have to be also emerged if extreme raise of temperature and explosion are involved in this problem; formulation is briefly mentioned and the results from numerical simulations are presented. It will be shown that the superheated vapor interacting with shock and temperature waves caused by the point charge inside of the underground open space may cause extensive occurrence of fissures on the surface exposed to the external loading envisaged.
Application of Gradient Based IR Thermography to the GRP Structures Inspection
Authors: Krstulović-Opara Lovre , Garafulić Endri , Klarin Branko , Domazet Željko
Published: September 2011

The article presents application of non destructive testing method based on the pulse heating infrared thermography used to detect material anomalies for the case of glass reinforced polymer structures. The goal of presented research, based on the thermal gradient approach, is to establish the procedure capable of filtering out anomalies from other thermal influences caused by thermal reflections of surrounding objects, geometry influences and heat flows for observed object.
3-Dimensional Stress Intensity Factor Determination for a Notched Shaft under Mixed Mode Loading
Authors: Nes Cristian Sorin , Faur Nicolae , Marsavina Liviu
Published: September 2011

Objectives: Numerical determinations of Stress Intensity Factors (SIFs) for a shaft under mixed-mode load with a crack of different sizes in the connection zone between square and circular cross-sections. Methods: Linear-elastic Fracture Mechanics principles are used. The numerical analysis program used was ABAQUS CAE version 6.9-3. The shaft consists in a circular section and a square section, with a fillet connecting zone. Cracks of different lengths and different depths are modeled. The shaft is subjected to torsion and bending. The SIFs were determined using the contour integral method. Results: The stress distribution was determined and plotted, and the stress concentration effect of the notches was highlighted. Crack propagation was also performed, using the XFEM module of ABAQUS code. The computed SIFs were plotted along the crack front. Conclusions: Crack initiation and propagation matched the pattern obtained in experimental tests, thus validating the model. The results confirmed that the fillet zone between the two sections acts as a stress concentrator. The fillet radius determines the magnitude of stress concentration. Crack geometry has a significant influence on SIFs, as well as on the global stress distribution.
Meshfree Continuum Damage Mechanics Modelling for 3D Orthogonal Woven Composites
Authors: Li L.Y. , M.H.Aliabadi Ferri , Wen Pi Hua
Published: September 2011

A Meshfree approach for continuum damage modeling of 3D orthogonal woven composites is presented. Two different shape function constructions, Radial basis (RB) function and Moving kriging (MK) interpolation, are utilized corresponding with Galerkin method in the Meshfree approach. The failure of two different unit cell models, straight-edge and smooth fabric unit cell model respectively, is compared.
Acoustic Damage Analysis of a Gear System
Authors: Belsak Ales , Prezelj Jurij
Published: September 2011

In diagnostics, noise can be a very reliable way of defining the condition of mechanical systems. There are different methods to visualise the noise source. Primarily, they deal with a specific noise source in a specific acoustic environment. This paper presents a visualization method of complex noise sources, using an acoustic camera. This method makes it possible to visualise all types of different complex noise sources; a special acoustic algorithm is applied for this purpose. Also, it is possible to observe various transient acoustical phenomena.