bluuebunny/crossref_metadata_2025 huggingface dataset:
Short Span Compressive Stress-Strain Relation and Model of Molded Pulp Material
Authors: Ji Hong Wei , Wang Huai Wen
Published: November 2010

Short span compressive experiments of molded pulp specimens were carried out on the SHIMADZU material test machine, resulting in the stress-strain curves. The analytic results indicate that the material density and the loading rate are the two major factors that influence the stress-strain relationships of the molded pulp materials. With the increase of material’s density, elastic modulus and ultimate strength both increase. With the increase of loading rate, elastic modulus decreases whereas ultimate strength increases. By analyzing the test results and the existing models, an improved stress-strain model for molded pulp material, with the two factors taken into consideration, has been proposed. The model coefficients are obtained by fitting against the short span compressive experimental data for the materials with different densities under different loading rate. Comparison made between the experimental results and calculated results indicates that the proposed model can well fit the stress-strain curves of molded pulp.
Analysis of Heating Steady Temperature Field in an Al1100/Ti-6Al-4V/SiC 2D-FGM Plane Plate by FEM
Authors: Xu Yang Jian , Wang Ling Ling , Du Hai Yang
Published: November 2010

The steady heat conduction problems under linear temperature load on upper surface in an Al1100/Ti-6Al-4V/SiC 2D-FGM plane plate are analyzed by the FEM. When the variation of the material composition in y-direction is linear, the plane temperature distributions with the changes of composition shape distribution coefficient mx and porosity coefficient Ax in x-direction are obtained. The results show that when mx<0.1, the temperature curve surface is upward convex. The smaller mx is, the bigger relative temperature gradient on the left side of the plate is. When mx>1.0, the temperature curve surface has smaller upward convex trend and becomes downward convex surface gradually with the increasing of the mx (except at =1). The bigger mx is, the bigger relative temperature gradient near the right ceramic side of the plate is. By comparison with the results of an Al1100/SiC 1D-FGM plate, in the 2D-FGM plane plate, when mx=0.5, the maximum value of the temperature difference near metal side increases by 15.6%, but the value near ceramic side reduces by 53%. The temperature curve surface has more obvious variation with the increasing of the Ax in the plate, especially it is when =0.3~0.5 and =0.2~0.5, the changes of the temperature difference value reach the maximum, and compared with Ax=0.0, the value of Ax=3.99 increases by 138.6% at =0.35 and =0.4. The results provide more comprehensive and concrete basis of calculation and the further analysis of thermal stress for the design and optimization of the 2D-FGM plane plate.
Improved Design of J-Box Steam Lines in Continuous Bleaching Range Based on TRIZ
Authors: Zhu Shi Fan , Hussain Waqar , Akbar Kashifa
Published: November 2010

The incorporation of TRIZ thinking seems to have elevated the capability of function analysis method to a higher level .This case study applies the TRIZ methodology to assist solve a problem for a process of continuous bleaching range. The focus is placed on identifying the cause of multiform degree of whiteness.
Sensor Fusion for Condition Monitoring System of End Milling Operations
Authors: Abbas Jabbar , Al-Habaibeh Amin , Su Dai Zhong
Published: November 2010

This paper describes the utilisation of multi sensor fusion model using force, vibration, acoustic emission, strain and sound sensors for monitoring tool wear in end milling operations. The paper applies the ASPS approach (Automated Sensor and Signal Processing Selection) method for signal processing and sensor selection [1]. The sensory signals were processed using different signal processing methods to create a wide range of Sensory Characteristic Features (SCFs). The sensitivity of these SCFs to tool wear is investigated. The results indicate that the sensor fusion system is capable of detecting machining faults in comparison to a single sensor using the suggested approach.
Sliding Mode Control of a Power Screw Driven Positioning Table
Authors: Bayar Gökhan , Konukseven (1) Erhan Ilhan , Koku A. Bugra
Published: November 2010

. Precise positioning and trajectory tracking control applications are important for industrial manufacturing and scientific research. Ball-screw, worm-gear, and power-screw driven systems are widely used for this purpose. Since power screw driven systems provide long range and allow precise servo control, they are commonly preferred. The control strategy developed for power screw driven systems is expected to be robust, to respond rapidly for fast tracking performance and to reject disturbances. These systems should also be controlled precisely in case of uncertainties. In order to enhance the overall system controllability, sliding mode control is one of the preferred strategies. In this paper, sliding mode control strategy developed for a power screw driven positioning table is introduced. Mathematical models of the power screw, positioning table and actuator subsystems are derived. An experimental positioning table setup consisting of a power screw is manufactured to which the developed controller is deployed for testing. The stability of the sliding mode controller is investigated in detail and its performance is compared to that of a PID controller for verification purposes.
Theory and Experiment Study on Transmission Error of Gear System
Authors: Shi Quan , Cheng Xiao Wei , Guo Dong , Shi Xiao Hui
Published: November 2010

Vibration and noise problems of the gear system have been widely concerned in recent years. A study of transmission error is conducted to verify the sources of the vibration and noise. The tooth meshing process is analyzed with consideration of the shaft, bearing, box, tooth deformation, and tooth micro-modification in this paper. The transmission error of a two-stage gearbox is discussed based on a theoretical calculation model of gear transmission error. Then the transmission error is measured in different conditions on a test system of two-stage gearbox. By comparing to the test data, the theoretical model of the two-stage transmission error has been refined and a more reasonable model is presented. The study plays an important role in reducing vibration and noise of the gear system.
Remanufacturer-Manufacturer Collaborative Model in the Same Channel
Authors: Wang Kai , He Rong Yao
Published: November 2010

This paper adds to the growing literature of market competition related to the remanufacturer by analyzing the model where the remanufacturer and the manufacturer collaborate with each other in the same channel. This paper investigates a single-period deterministic model which keeps the analysis simple so as to obtain sharper insights. The results characterize the optimal remanufacturing and pricing strategies for the remanufacturer and the manufacturer in the collaborative model.
Resisting Tracker Attacks by Query Terms Analysis
Authors: Ma Xiao Qi
Published: November 2010

Tracker attacks pose a serious threat to databases, especially those used in manufactory and management in industry. These attacks can be used to infer sensitive information in databases and they are difficult to detect. This paper proposes a new approach to dealing with such attacks by analysing each disjunctive term in every query statement. Potential tracker attacks will be detected and then suppressed to avoid any further real attacks. A sample database table and a sample attack are given and analysed to show the effectiveness of the new approach.
Structuring Interdependencies between Products and Networks of Partners
Authors: Zolghadri Marc , Zouggar Salah , Rassoulifar Rahi , Girard Philippe
Published: November 2010

Companies face new coordination challenges for product development projects in terms of technical and technological issues and internal or external resources. Projects managers have to deliver successful products on time and to budget and need to minimize industrial risks, while building up long term links across their supply chains. This paper describes briefly the Co-Evolution of Products and Network of PartnerS (CEPS) and insists on dependency the main concept behind it. CEPS is a framework that considers simultaneously the product development process and the design/deployment of associated network of partners. The CEPS tools look for understanding and identifying mutual dependencies between these two fields. This will provide management drivers for designers and managers.
Study on the Optimizing Scheduling Model of Ship-Based Aircrafts
Authors: Liu Qin Hui , Wang Neng Jian , Wang Jia Hui
Published: November 2010

Multi-aircraft scheduling is an importmant aspect to shorten the board handling operation time and increase the sorties of ship-based aircrafts launch out. In this paper, the factors such as the limited working space, the little resource and the complex operation task are taken into account. With the approach of multi-mode resource-contrained multi-porject scheduling, by allocating the station and resource to the aircrafts reasonably, a model which can reduce the maintenance time as much as possible is developed. The factors which effect the scheduling process are illustrated in the model. And a case study for this model is presented. The result of the case study shows that this mothod can reduce the operation time especially the maintance time reasonably.
Reduction of COD from Micro-Polluted Water through Adsorption of Activated Carbon-Attapulgite Composite Adsorbent
Authors: Wang Zheng , Jing Zhao Qian , Kong Yu , Shen Wei
Published: November 2010

The aim of this study was the assessment of reduction of chemical oxygen demand (COD) from micro-polluted water using activated carbon-attapulgite composite adsorbent prepared using activated carbon and natural attapulgite through compounding, granulation and calcination. The complete study was done in batch mode to investigate the effect of operating parameters. Adsorption of COD was found to be dependent on contact time, pH, temperature and initial COD concentration. Adsorption equilibrium attained within 80 minutes time. The optimum pH range for adsorption of organics was found to be 8. The sorption of organics decreased with rise of temperature because adsorption process was exothermic. The studied adsorption data fitted well to Langmuir adsorption model with the correlation coefficient 0.9947. The activated carbon-attapulgite composite adsorbent in this study shows very good promise for practical applicability on removal of COD from micro-polluted water.
Application of PDA and Wireless Technology in a Server-Client Structure for Remote Machine Condition Monitoring
Authors: Su Dai Zhong , Peng Wen Jie
Published: November 2010

A remote online machine monitoring system is developed across a desktop PC and mobile devices to monitor and control machine’s working conditions. A server-client network structure is constructed for real time communication between server and client modules. Within the server module, data I/O (input/output) communication is utilised to acquire machine condition data and to pass control commands to the machine-controller interface; feature extraction and decision making are applied to detect machine’s operating status. The server and client modules allow mobile users to remotely access the server via PDA and Wireless Wi-Fi connectivity to regulate the machine conditions by tuning the controller parameters. Remote communication between the modules with different platforms/operating systems is implemented by combining the Web Service application program interface with MXML-based cross-platform programming standard. The system developed is validated by a case study of monitoring the working conditions of an air-conditioning system.
Research on the Effect of Traction Tonnage on Train Longitudinal Impact
Authors: Ding Li Fen , Xie Ji Long
Published: November 2010

The traction tonnage has important effect on train longitudinal impact. An integrated model of train longitudinal dynamics was established based on simulation and test results. The effect of the traction tonnage on train longitudinal dynamics was investigated through modeling different types of heavy-haul trains. The model was validated by using measured longitudinal force time histories from on-track tests. Case study shows that the traction tonnage has significant influence on train longitudinal impact; Train longitudinal force increases with traction tonnage. The relationships between the maximum coupler forces (including tensile and compressive forces) and traction tonnage were obtained with the least square method for cases of train under emergency baking and release condition. The established train longitudinal dynamics model provides a platform for car body and coupler structure optimization and train control.
Principle of Conforming Water-Fuel Ratio for Metal Matrix Fuel Water-Ramjet Engine
Authors: Gao Ye , Liu Ping An , Wang Ge , Han Liu
Published: November 2010

When water-ramjet engine working, its water-fuel ratio is needed to conform. Taking magnesium-based fuel for example, thermodynamic parameter of different formulation fuel under different water-fuel ratio was calculated with the free energy minimization method. It was found that the effective specific impulse of water-ramjet engine increased first and then decreased with the increasing of water-fuel ratio, so there was the maximum value of it, named optimum specific impulse. The corresponding water-fuel ratio was the best one, and then the performance ability of water-ramjet engine was the maximum one. The temperature of nozzle exit gradually decreased with the increasing of water-fuel ratio. When the temperature was lower than local vaporization temperature, water steam coagulated and it would cause the thrust force to decline. Therefore, when the water-ramjet engine is designed, the value of water-fuel ratio can't exceed the best water-fuel ratio by the premise of guarantee of the temperature of nozzle exit as high as possible.
Application of Fiber Bragg Grating Sensor to Monitor Early Age Deformation of High Performance Concrete
Authors: Yun Ying Wei , Wang Xin Wu , Jang Ii Young , Kim Sung Soo
Published: November 2010

This paper presents a method to monitor the early age properties of high performance concrete (HPC) specimens successfully by embedded fiber bragg grating (FBG) monitoring system. The results show that the deformation increases rapidly within the first 30 hours after HPC casting. And its value is up to 65 µε and 84µε for two specimens respectively. As for the durability and permeability of HPC, early age deformation of HPC is pretty high and can not be neglected. Meanwhile, temperature compensation technique for FBG strain sensor has been put forward, and it is applied to measure early age deformation and temperature of HPC beam in situ simultaneously. The monitoring technique used here can be extended to concrete early age behavior monitoring in mass concrete structure with any size.
A Coupled Finite Element and Element-Free Galerkin Method for Rigid Plastic Problems
Authors: Li Di , Kang Wen Qian , Guo Peng Wei
Published: November 2010

The analysis for rigid plastic forming problems with finite element method can lose considerable accuracy due to severely distortional meshes. By measuring the mesh equality of elements, a coupling algorithm for rigid plastic problems have been proposed based on the interface element method, which converts the FE analysis into the EFG computation to preserve the accuracy in the region where meshes have been severely distorted. Numerical example shows that the present algorithms exploit the respective advantages of both the FE method whose computational efficiency is high and the EFG method which can throws out mesh distortions and be suitable for rigid plastic forming analysis.
Application of Optimization Analysis on Structure Damage Identification Based on ACO Algorithm
Authors: Hu Ming Yi , Zhang Ling Xin
Published: November 2010

The present paper addresses the subject of structural DI (damage identification). ACO (Ant Colony Optimization) is a kind of new intelligent optimization algorithm which is based on simulation of ant group behavior. This algorithm is characterized with strong robustness, distributed computing mechanism and higher efficiency. In this paper, firstly, the feasibility and principle to make DI by FE (Finite Element) method is introduced. Then, the structure of ACO algorithm used in TSP (Traveling Salesman Problem) structure is also illustrated and the flow chart of the program is given. Furthermore, SACO (substructure ACO) method is proposed to improve efficiency and applied in a three-bay three-story frame. In conclusion, on the one hand, efficiency about ACO algorithm applied into structure DI is proved to be high during the searching process, on the other hand, the new method of SACO is applied during the whole calculation, and the conclusion indicates that it could improve the calculating efficiency and stability instead of too much complicated analysis for enter the local optimization search scope beforehand.
A Female Glasses Fitting Model Based on Neural Network
Authors: Tseng Sei Wo Winger , Tsai Hung Cheng
Published: November 2010

A neural network based approach for female eye glasses fitting suggestion is addressed in this article. The experimental results are analyzed by two stages of back-propagation neural network, which first categorize the Taiwan female faces, and then establish the relationships between adjective image words and female faces with different glasses. A female glasses fitting model was then developed based on these database. With the aid of the model, a glasses store or an electronic store can generate professional fitting opinions to its female customers after a practical ophthalmic dispensing. Although the system is mainly designed for a Taiwan female face, the method can be used to develop for other countries or products.
Genetic Algorithm Based Methodology for Optimal Maintenance Scheduling of Multi-Unit Systems
Authors: Yan Ji Hong , Wang Yu Yan , Zhang Xu
Published: November 2010

This paper presents a novel methodology for optimal maintenance scheduling of multi-unit systems under predictive maintenance (PdM) environment. A maintenance scheduling model for multi-unit system is established considering performance degradation of units, dynamic characteristics of the system, economic dependence and structural dependence between units, and constraints of maintenance resources. The deterioration of units is modeled by Weibull distribution. Three maintenance actions, as minor repair, imperfect overhaul and replacement are considered to arrange the PdM schedule of a system. The genetic algorithm based methodology is employed to obtain the near optimal scheduling which results in a relatively minimal maintenance cost rate. The scheduling results demonstrate that the proposed methodology is feasible and effective.
Simulation on the Biomass Direct-Fired Stirling Engine
Authors: Zhang Xu , Ma Yan , Zang Jie , Chen Tie , Yin Jing , Zhang Peng
Published: November 2010

The theoretical analysis of the working principle of the β-type Stirling engine was carried out. According to the constraints of their mathematical model, an analysis was made through the MATLAB/Simulink simulation software, and the simulated curves are generated under the different parameters which were used to compare and research. The results show that the output power and the pressure of the cylinder change with the different pressure, temperature, swept volume and the cylinder volume, and which reflect the influencing factors of the power. The simulation gives an intuitive theoretical basis for the design and optimization of the direct-fired biomass Stirling engine, and points out the direction of the development of the biomass energy in the new period.
A Skill-, Rule-, and Knowledge-Based Interaction Design Framework for Web-Based Virtual Reality Training Systems
Authors: Lin Chiuhsiang Joe , Lin Shiau Feng , Wang Rou Wen , Sun Tien Lung , Chao Chin Jung , Feng Wen Yang , Tseng Feng Yi
Published: November 2010

Virtual Reality (VR) systems have been applied for education, training and entertainment purposes in the areas of military, safety training and flying simulators. In particular, Web-based VR training systems (WBVRTS) have been claimed to have great potential for many applications in training. However, WBVRTS are more complex compared with the traditional training methods which rely on manuals, instructions, and videos. Since VR not only reinforces the visual presentation of the training materials but also provides ways to interact with the training system, it becomes more flexible and possibly more powerful in designing the training system. In this study, we propose a WBVRTS framework based on SRK framework. A combat vehicle maintenance training system was developed into WBVRTS following the framework and structure. The proposed SRK framework for VR training system proved useful in guiding the design and development of the training materials. The study suggests that the design of VR as training tools should be based on user interaction and cognitive theories that support effective learning.
Study on Bolted Joints of U Frame of Simulation Turntable
Authors: Li Qiu Hong , Zhang Jia Tai , Wang Ping , Xue Kai
Published: November 2010

The simulation turntable is a high precision and semi-physical simulation installation. In order to meet high precision of turntable, the precision prescribed in all sets of axes of turntable is required during manufacturing process and assembly. Based on assembly process of three-axis simulation turntable, the detachable structure of U frame is designed. Components of the frame are formed by bolted joints. So the strength and stiffness of the U frame with bolted joints must meet initial design requirements, simple and reliable finite element simulation method of bolted joints is applied based on ANSYS software in the paper. The connection of screw threat pair is simulated by nonlinear elastic contact mode, and the preload to bolts is loaded though pretension element of ANSYS software. The numerical analysis is performed to confirm that the detachable structural U frame with bolted joints is satisfied with structural requirement and the strength of U frame is influenced by the pre-tightening force of bolt at the extent.
Bionic Research of Turtle Hydrofoil Propulsion
Authors: Xu Jian An , Sun Li Ning , Zhao Wen De , Liu Xiao Bai , Yan Na
Published: November 2010

The hydrofoil propulsion method, which takes marine turtle forelimb as representative, has the outstanding characteristics of high efficiency and low noisy so that the bionic research of turtle forelimb hydrofoil propulsion was conducted. Taking the ripe green-turtle as living prototype, the turtle hydrofoil propulsion motion principle was studied, and then the bionic hydrofoil propulsion sample was developed. According to the Newton’s second law of motion and Euler’s formula, the 6 DOF space motion expression of bionic sample was established. At last, the motion performance test experiment of bio-hydrofoil machine was carried out, and the experimental results not only provided a control element for the motion attitude control of the sample, but also validated the security and availability of the bionic system design, enriching the underwater flexible propulsion theories.
Dynamic Response of an Overhead Crane Beam Due to a Moving Mass Using Moving Finite Element Approximation
Authors: Gerdemeli Ismail , Esen Ismail , Özer Derya
Published: November 2010

In this study, dynamic behaviour of a beam system of an overhead crane is investigated. A MATLAB code is developed for numerical analyses. The moving mass on the beam is modelled as a moving finite element to include inertial effects of mass. Dynamic response of the beam is obtained depending on the mass ratio between load and beam mass. Besides, a variety of mass velocities are considered. Analysis are carried out considering mass ratio (mass of the load/mass of the beam m/M) as 0.1, 0.2, 0.4, 0.6, 0.8 and 1 and mass velocities as 1, 2, 4, 8, and 12.5 m/s. Dynamic response of the beam depends on velocity and mass of moving load. As the position of the moving mass in the span changes, it alters the natural frequency of the beam system. Generally, if the mass velocity increases, maximum beam deflection occurs far from the beam midpoint. For some values of the velocity, the maximum response may occur before the beam midpoint. At very high speeds, the maximum beam deflection occurs near the beam endpoint. At very slow speeds, the maximum beam deflection occurs near the midpoint because the system reduces to a quasi-static solution. At the same mass ratio, load velocity increases, with the increment of the beam deflection. Both mass velocity and mass ratio affects the dynamic response of the beam but the effect of velocity is greater than the mass ratio.
Porphyrins as Potential Sensitizers for Dye-Sensitized Solar Cells
Authors: Imahori Hiroshi
Published: November 2010

Recently, dye-sensitized solar cells have attracted much attention relevant to global environmental issues. So far ruthenium(II) bipyridyl complexes have proven to be the most efficient TiO2 sensitizers in dye-sensitized solar cells. However, the highest power conversion efficiency has been stagnated in recent years. More importantly, considering that ruthenium is rare and expensive, novel dyes without metal or using inexpensive metal are desirable for highly efficient dye-sensitized solar cells. To fulfill the requirement, it is crucial to develop inexpensive novel dyes that exhibit high efficiencies in terms of light-harvesting, charge separation, and charge collection. Porphyrins are important classes of potential sensitizers for highly efficient dye-sensitized solar cells owing to their photostability and potentially high light-harvesting capabilities that would allow applications in thinner, low-cost dye-sensitized solar cells. However, typical porphyrins possess an intense Soret band at 400 nm and moderate Q bands at 600 nm, which does not match solar energy distribution on the earth. Therefore, the unmatched light-harvesting property relative to the ruthenium complexes has limited the cell performance of porphyrin-sensitized TiO2 cells. Elongation of the -conjugation and loss of symmetry in porphyrins cause broadening and red-shift of the absorption bands together with an increasing intensity of the Q bands relative to that of the Soret band. On the basis of the strategy, the cell performance of porphyrin-sensitized solar cells has been improved remarkably by the enhanced light absorption. The efficiency of porphyrin-sensitized solar cells could be improved significantly if the dyes with larger red and near-infrared absorption could be developed.
Anisotropic Fracture Behaviour of Progressively Drawn Pearlitic Steel
Authors: Toribio Jesús , González Beatriz , Matos Juan Carlos , Ayaso F.J.
Published: November 2010

This paper analyses the differences in fracture behaviour of two cold drawn pearlitic steels with different degree of strain hardening: a slightly drawn bar and a heavily drawn wire. The load-displacement curve F-u was analysed in the two cases, with special emphasis in the characteristic points of the plot: the load defining the end of linear behaviour (Fe), the final fracture load (Fmax) and, in the heavily drawn steel, the pop-in load (FY). Results demonstrate that slightly drawn steels exhibit isotropic fracture behaviour with crack propagation along its own plane (mode I propagation). On the other hand, heavily drawn steels exhibit a markedly anisotropic fracture behaviour with crack deflection (mixed mode propagation), and vertical fracture embryos suddenly appear associated with the pop-in instant. This special fracture mode is a consequence of the markedly oriented microstructure of the heavily drawn steel.
Elastoplastic Seismic Response Analysis of Masonry Buildings with Variable Wall Thickness along Height
Authors: Sun Bai Tao , Chen Hong Fu
Published: November 2010

The multistory masonry buildings with variable wall thickness along the height have suffered different degrees of damage subjected to the Wenchuan earthquake. In order to study the failure mechanism of such masonry structure under the earthquake, three types of five-story structure of computational model are firstly introduced in this paper, including (1) the wall thickness of five stories is 240mm; (2) the wall thickness of the first floor is 370mm, and that of the upper four stories is 240mm; (3) the wall thickness of the first and second story is 370mm, and that of the other stories is 240mm. Then, the elastoplastic time-history dynamic analysis is carried on with the story shear model by the finite element method, and the ground motion of El Centro waves are adopted as earthquake input motion. The analysis results show that variation of wall thickness along height can easily cause stiffness mutation of the upper and lower floor, lead to local floor deformation concentration and soft floors, and the change of failure mechanism of the structure. Finally, it is suggested that some appropriate seismic resistance measures should be taken to meet the lateral stiffness ratio of the upper and lower floor in the later design of this structure, or this kind of structure should be avoided using as far as possible.
The Effect on Dynamic Properties of Reactive Powder Concrete under High Temperature Burnt and its Micro-Structure Analysis
Authors: Pang Bao Jun , Wang L.W. , Yang Z.Q. , Chi Run Qiang
Published: November 2010

In this paper, the dynamic macroscopical properties of reactive powder concrete (RPC) are studied by using the split Hopkinson pressure bar (SHPB) system. The effect on dynamic properties of RPC material with different water binder ratio (W/B) and steel fiber influence under high temperature burnt is discussed. And scanning electron microscope (SEM) technology is also used to investigate the micro-structure change under high temperature burnt. The experiment result shows: without high temperature burnt, the higher water binder ratio, the lower dynamic compression strength of RPC material. With high temperature burnt, strength decreases exquisite. However, steel fiber can prevent micro-crack from generating, the toughness effect still alive after high temperature burnt. From SEM analysis: the inner part of RPC will have a series of physical chemistry changing, such as: micro-crack generation, C-S-H gel damage. This essential change is the basic reason for dynamic properties degrade.
The Steady-State Growing Crack-Tip Field Characteristics of Mode I Elastic-Viscoplastic/Rigid Interface Cracks
Authors: Liang Wen Yan , Wang Zhen Qing , Lv Hong Qing
Published: November 2010

The existence of viscosity effect at the interface of double dissimilar materials has an important impact to the distribution of interface crack-tip field and the properties variety of the interface itself. The singularity and viscosity are considered in crack-tip, and the elastic-viscoplastic governing equations of double dissimilar materials at interface crack-tip field are established. The displacement potential function and boundary condition of interface crack-tip are introduced, and the numerical analysis of elstic-viscoplastic/rigid interface for mode I are worked out. The stress-strain fields are obtained at the crack-tip and the variation rules of solutions are discussed according to each parameter. The numerical results show that the viscosity effect is a main factor of interface propagating at crack-tip field, and the interface crack-tip is a viscoplastic field that is governed by viscosity coefficient、Mach number and singularity exponent.
Parametric Generation of Random Distribution of Fibers in Long-Fiber Reinforced Composites and Micromechanical FE Analysis
Authors: Wang Zhen Qing , Wang Xiao Qiang , Zhang Ji Feng , Zhou Song
Published: November 2010

A method for the parametric generation of the transversal cross-section microstructure model of unidirectional long-fiber reinforced composite (LFRC) is presented in this paper. Meanwhile, both the random distribution of the fibers and high fiber volume fraction are considered in the algorithm. The fiber distribution in the cross-section is generated through random movements of the fibers from their initial regular square arrangement. Furthermore, cohesive zone element is introduced into modeling the interphase between the fiber and the matrix. All these processes are carried out by the secondary development of the finite element codes (ABAQUS) via Python language programming. Based on the model generated, micromechanical finite element analysis (FEA) is performed to predict the damage initiation and subsequent evolution of the composites. The results show that this technique is capable of capturing the random distribution nature of these composites even for high fiber volume fraction. Moreover, the results prove that a good agreement with the experimental results is found.
Mechanical Behavior of Structural Concrete Made with Recycled Aggregates from Tunnel Excavation
Authors: Antonaci Paola , Masera Davide
Published: November 2010

The results of an experimental study concerning the behavior of concretes made with recycled aggregates under repeated mechanical and thermal actions are presented. A comparison with the performances achieved by similar concretes made with traditional aggregates in the same working conditions eventually made it possible to estimate the actual quality and durability of the recycled concretes examined and identify possible limitations in their use. The laboratory protocol here adopted is suggested as a practical experimental procedure to test hardened concretes and pre-qualify their performances with respect to compressive actions and thermal solicitations.
Cyclic vs. Static Loading Behaviour of Masonry Blocks: An Approach to Evaluate the Long-Term Behaviour
Authors: Antonaci Paola , Bocca Pietro G. , Masera Davide
Published: November 2010

The paper presents the results of an experimental investigation conducted on bricks. Prism-shaped specimens were produced. Laboratory tests were carried out at the Non-Destructive Testing Laboratory of the Politecnico di Torino. They were subjected to static compressive tests for the determination of their mechanical properties and cyclic compressive tests for the analysis of their fatigue behaviour. The aim of this work is to apply a failure criterion based on the observation of the static and cyclic curves to estimate the fatigue life and the long-term behaviour of the brick. Subsequently, it will be possible to give a relation between the static-displacement and cyclic-displacement of the material tested.
Environmental Fatigue of 7075-T6 Aluminum Alloy
Authors: Ebara Ryuichiro , McEvily A.J.
Published: November 2010

The fatigue lifetime of the aluminum alloy 7075-6 depends upon the cyclic stress
amplitude and the environment. At an R value of 0.05, and a maximum stress of 400 MPa the
lifetime in vacuum is an order of magnitude greater than that in air, but interestingly at a maximum
stress of 275 MPa, the lifetime in vacuum is only three times that in air. It was noted that well
defined striations were observed in air, whereas striations were absent in vacuum, instead
indications of ductile rupture were observed. The mechanism of fatigue crack initiation and
propagation behavior as influenced by the environment is discussed.
The Effect of Damage and Geometrical Variability on the Tensile Strength Distribution of Flax Fibers
Authors: Andersons Janis , Spārniņš E.
Published: November 2010

Natural fibers of plant origin are finding non-traditional applications as reinforcement of composite materials. The mechanical properties of fibers exhibit considerable scatter, being affected by the natural variability in plant as well as the damage accumulated during processing. For bast fibers, the primary damage mode is kink bands – zones of misaligned cellulose microfibrils extending across the fiber and oriented roughly perpendicularly to its axis. Another feature typical for natural fibers and contributing to the scatter of fiber strength is the variability of diameter along a fiber length and among the fibers. An analytical expression for the distribution of the longitudinal tensile strength of bast fibers has been derived, accounting for the strength variability of intact fibers and the effect of kink bands. Upon determining the relevant parameters from fiber damage and geometry characteristics by means of optical microscopy, the theoretical strength distribution function has been found to agree reasonably well with the test results of elementary flax fibers.
Asymptotic Field near the Tip of a Mode I Quasi-Statically Propagating Crack in Rate-Sensitive Materials
Authors: Li Jia Lei , Jia Bin , Wang Zhen Qing , Pang Bao Jun
Published: November 2010

An elastic-viscoplastic constitutive mode was adopted to analyze asymptotically the tip field of a mode I quasi-statically propagating crack in rate-sensitive materials under plane stress condition. Under the assumption that the viscosity coefficient is a power law function of the rate of effective plastic strain, it was obtained through dimension match that the crack tip field possesses power law singularity. And the singularity exponent is uniquely determined by the power law exponent in the supposed viscosity coefficient. The elasticity, plasticity and viscosity of material at crack-tip only can be matched reasonably under linear-hardening condition. Variations of crack tip field characters according to each material parameter were discussed by means of numerical computation. The stress intensity is dominated by the material viscosity whereas the hardening coefficient has less significant influence on tip field. Furthermore, the solution can be transformed to the elastic-nonlinear-viscous one of Hui and Riedel if the limit case of zero hardening coefficient is considered.
Toughening Analysis of Mixed Cracks in Transformation Toughened Ceramics on Influence of SD Effect
Authors: Wang Zhen Qing , Yang Zeng Jie , Tang Li Qiang
Published: November 2010

Considering the SD effect, the parabolic-type yield criterion is obtained by using a new parameter. And by analogy with associated plastic flow rule, the ceramic phase transformation constitutive model is established. Under plane strain condition, the theoretical toughening expressions of mixed-mode I-II stationary cracks and steady-state growing cracks are developed by applying the weight function method. And the toughening effect is discussed under the influence of Poisson ratio, parameter and . The simulation results show that these phase transformation toughening effects are in good agreement with experimental results. And comparing with other yield criterions, it is more in line with actual characteristics of zirconia ceramic materials, when the expression of mixed I-II crack is reduced to mode I crack. And it also could provide theoretical support and reference for the further research of ceramic phase transformation toughening.
Analysis of Thermo-Mechanical Behavior of Shape Memory Alloys
Authors: Lei Hong Shuai , Wang Zhen Qing , Zhou Bo , Wang Yu Long
Published: November 2010

Shape Memory Alloy (SMA) is widely used and plays an important role in various engineering fields due to its special characteristics of shape memory effect and super-elasticity. In this paper the phase transformation behavior and thermo-mechanics behavior of 50.0at%Ni-Ti SMA are investigated though differential scanning colorimeter (DSC) and tensional tests respectively. Optical micrographs show the transformation of austenite and twinned martensite. The comparing numerical calculation result with tensional test result shows the new macro-mechanical constitutive equation can express the thermo-mechanical behavior of SMA effectively.
Role of Rate and Temperature on Fracture and Mechanical Properties of PCD
Authors: Petrović Marin , Carolan Declan , Ivanković Alojz , Murphy Neal
Published: November 2010

Polycrystalline diamond compacts (PDC) cutters are widely used in oil and gas well drilling and a different format of the same material is also used in high speed turning. During the cutting process these tools experience very high temperatures and impact loads which lead to their sudden fracture. In this work the mechanical and fracture properties of two different grades of PCD test specimens, i.e. the Young’s modulus and fracture toughness, are measured under a range of test conditions such as temperature and loading rate, which correspond to the actual drilling conditions. The fracture is found to propagate in a highly dynamic manner, where the results show the examined properties of PCD specimens to vary with the loading rate and temperature. The study performed leads to a greater understanding of PCD behaviour, and aims to provide guidance for improved material design.
Fatigue Crack Growth Rates of HPS 485W in China
Authors: Wang Chun Sheng , Duan Lan , Hu Jing Yu
Published: November 2010

This paper provides an introduction of existing fatigue and fracture behavior studies about high performance steel (HPS). This paper is emphasis on the crack propagation studies of HPS 485W, which is a new kind of structural weathered steel produced by Wuyang Steel Company using quenching and tempering (Q&T) in China. HPS has more advantages than traditional steel, such as high fracture toughness and cracking tolerance, high strength, low preheating weld or no preheating, recycle using and so on, so it can be used in sustainable bridge and building structures with low carbon releasing. To ensure the using safety and extend applying area of the new green civil material, the key material properties of HPS should be studied, such as fatigue crack growth rate. Fatigue crack growth rate characterizes the material resistance to stable crack extension under cyclic loading. A set of 5 compact specimens were made from 8mm and 14mm thick HPS 485W separately. Fatigue crack growth rate function of crack-tip stress-intensity factor range, da/dN versus ΔK, is proposed based on the test results, which shows HPS has high cracking tolerance ability.
Floor-Beam Web Cutout Shape Analysis to Improve the Fatigue Resistance in Orthotropic Steel Bridge Decks
Authors: Wang Chun Sheng , Zhang Qin , Zhang Tao , Feng Ya Cheng
Published: November 2010

The modern steel orthotropic decks have been used in steel bridges for 60 years all over the world because of its super structural advantages. Recently, more bridge owners, engineers and researchers pay more attention to the fatigue problem of orthotropic steel decks for a large number of fatigue cracks found in steel bridges. For example, bridge engineers have detected hundreds of fatigue cracks in steel orthotropic deck on the 888-meter long box girder of Humen Bridge only ten years after opening to traffic. How to design or repair the fatigue details in orthotropic steel decks is the critical question to be solved at first step. In current paper, the elaborate numerical analysis model of the orthotropic steel bridge decks was developed using ANSYS software with different floor-beam web cutouts shapes, such as conventional ellipse, circular, trapezoid and Haibach web cutouts. The finite element models were calibrated by static test of one full size orthotropic steel bridge deck model. According to the analysis results, it should select the rational cutout shapes based on actual load and structural conditions in steel bridge deck design and strengthening.
Computational Analysis of the AFM Specimen on Mixed-Mode II and III Fracture
Authors: Li Qing Fen , Zhu Li , Buchholz Friedrich G. , Yan Sheng Yuan
Published: November 2010

Some results of 3D finite element analyses of the all fracture modes (AFM) specimen on mixed-mode II and III fracture are presented in this paper. The computational fracture analysis is based on the calculation of separated strain energy release rates (SERRs) along the crack front by the modified virtual crack closure integral (MVCCI)-method and the commercially available FE-code ANSYS. Calculation results show that under pure in-plane shear loading (mode II), not only the mode II, but also the mode III loading conditions, are generated owing to the Poission’s ratio effects. Similarly, under pure out-of-plane shear loading (mode III), besides the mode III, the mode II loading conditions are induced due to the global deformation. Nevertheless, once in-plane and out-of-plane shear loadings are superimposed, the fracture behavior appears more complex. Further discussion is given associate with some previous study.
Self-Oscillation Cavity Design and Flow Field Analysis of Pipeline Supercharger
Authors: Ren Zheng Yi , Li Qing Fen , Zhao Xiao Li , Li Li Kun
Published: November 2010

The self-oscillation device has many advantages and is therefore suggested to be used in the pipeline supercharger. Simulation and analysis on the pressure-increasing effect of the pipeline supercharging caused by self-oscillation cavity were carried out by finite element method. The cavity structure of self-oscillation device was designed using the fluid network theory, natural frequency calculation, resonance conditions and Large Eddy Simulation Theory. A series of flow field distribution chart of the self-oscillation cavity were obtained. Results validate that the self-oscillation device is effective to increase the pressure of the pipeline supercharger. The relation curves of pressure-increasing effect with different structure parameters of the cavity were further analyzed. Previous experimental results are accordant with the present simulation results. It shows that the numerical analyses are reliable.
Microbiological Influenced Corrosion Behavior of Full-Coated and Nicked-Coated Specimens
Authors: Wang Jun , Fu Yu Dong , Li Qing Fen , Li Chun Hui
Published: November 2010

The microbiological influenced corrosion (MIC) behavior of the low alloy steel with Zn-rich epoxy coating and micaceous iron oxide epoxy coating in the sterilized medium and sulfate-reducing bacteria (SRB) solution was investigated by using both full-coated and nicked-coated specimens. Results show that for steel coated with Zn-rich epoxy, the corrosion resistance of both full-coated and nicked-coated specimens was improved obviously. The Zn-rich epoxy coating protected the test steel effectively in the microbial environment with the cathodic protection in the earlier period and physical barrier protection in the later period. For steel coated with micaceous iron oxide epoxy coating, the corrosion resistance of full coated specimens was improved greatly. However, for nicked-coated specimens, corrosion was aggravated because the small anodic area around the nick accelerated the corrosion. It is concluded that the basic low alloy steel may be effectively protected by the micaceous iron oxide epoxy coating only when the steel is perfectly coated with the coating, breakage must be avoided.
Numerical Investigation of Penetration Performance of Segmented Rod Projectiles with Various Connectors
Authors: Cao Zong Sheng , Deng Yun Fei , Zhang Wei
Published: November 2010

In this paper, a series of numerical simulations have been conducted to investigate the penetration performance of tungsten alloy segmented rods with various connectors and different design parameters, and corresponding continuous rod penetrate into semi-infinite thick steel target at velocities from 1.5 km/s to 3.1 km/s. The SPH hydrocode of AUTODYN was used in this paper to reveal the influences of design parameters on the penetration performance of segmented-rod projectiles. A non-ideal segmented rod projectile includes not only segmented rods but also carrier tube and connectors for assembly and integrity purposes. The penetration performance of penetrator is evaluated by examining the crater depth in thick steel targets.