bluuebunny/crossref_metadata_2025 huggingface dataset:
Kinematics Analysis of a New 5 DOF Parallel-Serial Machine Tool Based on the Vector Method
Authors: Wang Rui , Ding Gang , Zhong Shi Sheng
Published: November 2010

A 5-axis parallel-serial machine tool is proposed, which consists of a 3-DOF parallel mechanism and a 2-DOF serial mechanism, and the kinematics analysis is discussed in detail based on the vector method. The size of the velocity transformation matrix is decreased. The problem of parameter coupling is resolved by adopting identity matrix and four-element vector. The relationship between the velocity and acceleration of the movable platform and the input parameters of the parallel mechanism is established. These algorithms are verified correct through ADAMS (Automatic Dynamic Analysis of Mechanical System) and can be referenced by kinematics analysis, dynamics analysis of parallel or parallel-serial machine tools, which have coupling kinematics parameters.
Manufacturing Quality Control Method Based on Bayesian Network Model
Authors: Dong Ye Hong , Xiang Dong , Duan Guang Hong
Published: November 2010

In order to address the problem of quality control faced in multi-type and small-batch manufacturing mode, the method based on Bayesian Network (BN) is proposed. The building, learning and evolving method as well as the quality prediction and diagnosis method of BN model are described in this paper. The combination of BN model and Shewhart control chart is also mentioned. The model building and evolving method was conducted in PCB micro-drilling process as example, verifying that the prediction accuracy increases with the evolved model. The drilling quality prediction was compared with that obtained through regression analysis and artificial neural network. The advantage of BN model in advanced manufacturing is proved.
Research on Twin-Arc TIG Welding with Ultrasonic Excitation and Its Effect to Weld
Authors: Wang Jian Jun , Hong Xiao Ou
Published: November 2010

. In order to enhance the mechanical properties of weld by using ultrasonic vibration, a new method of twin-arc TIG welding was developed. The welding will be completed by jointly using combined ultrasonic arc and ordinary DC arc technology. The ultrasonic arc was used for injecting ultrasound excitation into the molten pool to improve weld quality, and the DC arc was used as main heat source to increase deposition efficiency. The feasibility experiment of the welding system was done by using the steel 304. Metallographic analysis shows that the method can thin the microstructure of weld. The tensile testing under nature temperature indicates that the method can improve tensile properties of the weld effectively.
Particle Swarm Optimization Method for Panel Layout
Authors: Xu Yu Qing , Yang Zhi , Meng Qing Xin
Published: November 2010

Panel layout in control room of nuclear power plant requires satisfying layout principles and requirement for multiple operational conditions. Traditional panel layout methods are difficult to integrate these principles; the layout scheme heavily depends on designers’ individual judgments and experience. So the randomness of layout scheme is hard to overcome. Particle swarm optimization is a global efficient solution to complex optimization problems with multi-constraints. First, the operational efficiency is selected as optimization object. Second, objective function is constructed according to the evaluating indexes which include operation frequency, sequence and importance of components. Third, Particle swarm algorithm was used to optimize the layout scheme. A case study of layout optimization design is conducted to illustrate the proposed method.
Design and Analysis of a Tapered Deployable Mast
Authors: Deng Q. , Li Bing , Huang H.L. , Liu Rui Qing , Deng Zong Quan
Published: November 2010

. Deployable truss has a wide range application in aerospace industry. Two important issues in the design of all deployable space structures are the weight and its stiffness in the deployed state. This is because lower weight of deployable truss can greatly save the cost of launching and higher stiffness can improve the loading capacity. This paper aims to design a tapered deployable mast with lower weight and higher stiffness. The mobility analysis and geometry condition is first introduced. Then structural optimization problem with mass as its objective is solved by using ANSYS Parametric Design Language (APDL). The optimal results show the proposed tapered mast has excellent performance on mechanical properties by comparing with normal mast with identical cross section. Finally, some possible applications and problems are described.
Machine Vision-Based Intelligent Fire Fighting Robot
Authors: Ho Chao Ching , Chen Ming Chen , Lien Chih Hao
Published: November 2010

Designing a visual monitoring system to detect fire flame is a complex task because a large amount of video data must be transmitted and processed in real time. In this work, an intelligent fire fighting and detection system is proposed which uses a machine vision to locate the fire flame positions and to control a mobile robot to approach the fire source. This real-time fire monitoring system uses the motion history detection algorithm to register the possible fire position in transmitted video data and then analyze the spectral, spatial and temporal characteristics of the fire regions in the image sequences. The fire detecting and fighting system is based on the visual servoing feedback framework with portable components, off-the-shelf commercial hardware, and embedded programming. Experimental results show that the proposed intelligent fire fighting system is successfully detecting the fire flame and extinguish the fire source reliably.
Optimal Design of Gear Transmission System of Increasing Speed for Half-Direct-Drive Tidal Current Energy Station
Authors: Kong Fan Kai , Yin Su Ge , Lin Hong Yun , Sheng Qi Hu
Published: November 2010

The half-direct-drive transmission is conducted for the transmission system of tidal current power stations using a small speed-up ratio of planetary gearbox between turbine and generator. A design model is developed for the optimization of the planetary gear transmission system. And a mixed genetic algorithm is applied on the basis of fundamentals of genetic algorithm to carry out the optimization. From the example calculation, a better design scheme is obtained by the optimization.
A Dynamic Fluid Property Model for the Engineering Design of Hydraulic Dampers
Authors: Wang Wen Lin , Xia Xiao Feng , Xu Gao Xin
Published: November 2010

To improve accuracy in the engineering design of hydraulic dampers, a dynamic mathematic model for its working fluid density, viscosity, modulus and stiffness is established. The dynamic flow loss due to volumetric change and pressure leakage is also formulated, wherein the dynamic back pressure in the air chamber is coupled. Simulation results show that most of the fluid properties change obviously when the damper is subjected to external excitations, they are not constant values. The viscosity would drop 74.68% and the flow loss would soar 298.68% with the increase of fluid temperature; the modulus and the stiffness would also drop over 20% when the entrapped air ratio increases, but the density is relatively robust to both variations. The established mathematic model gives a dynamic representation of the fluid property under real service conditions, it has already been applied to the engineering design of several hydraulic damper products in industry, and the effectiveness is validated by pertinent product experiments.
The Radial Stiffness and Application of Double-Decker Ball Bearing
Authors: Zhu Yi Li , Xu Long Xiang
Published: November 2010

Single Decker Ball Bearing (SDBB) is widely used in Rotor-Bearing system. A new method using DDBB composed of two ball bearings as support bearings is proposed. The mechanical model of the DDBB based on the quasi-dynamic method is established and the corresponding calculating program compiled in Matlab is developed after considering the radial load, axial load, centrifugal force as well as gyroscopic moment acted on the bearing simultaneously. And then a simple Rotor-DDBB model is adopted to analyze the rotor unbalance response with different parameters. The simulation results show that shaft rotating speed, ball materials, axial preload and the initial contact angles to some extent impact the bearing stiffness while have little affects on system nature frequency and the rotor unbalance response which greatly affected by the system base stiffness. The results provide a theoretical basis for the design of DDBB and application in a Rotor-Bearing system.
Logistics Efficiency Improvement with Lean Management and RFID Application
Authors: Chen James C. , Wang Kung Jeng , Cheng Chen Huan , Fang Yuh Jiun , Sun Cheng Ju , Chien Jui Wei
Published: November 2010

This study illustrates the application of lean management and Radio Frequency Identification (RFID) technology to improve the logistics efficiency in a distribution center. The distribution center stores more than ten million parts belonging to about ten thousand types. There are more than ten thousand storage and retrieval operations for hundreds of part types on a daily basis. Value stream mapping was used to draw current state mapping with material flow, information flow, and time flow. Based on the concept of business process reengineering, future state mapping with RFID application was developed. Preliminary experiments showed that 100% read rate was achieved with a fixed RFID reader and an antenna installed at a garage door and Ultra-High Frequency passive tags mounted on each pallet. The benefit using RFID in the distribution center is analyzed (e.g., with a saving of cycle time and process time by 24% and 22%, respectively) and promoted.
A Version Control Approach for Workflow-Alteration in Collaborative Design
Authors: Shiang Wei Jung , Lin Mian Shiu , Rau Hsin
Published: November 2010

The workflow management system should be flexible enough to manage workflow changes caused by new partnerships, new technologies, and new strategies in collaborative design. Therefore, this paper attempts to introduce the version concept of configuration management into the workflow management system to handle this problem. In this study, the baseline is applied to record the sequence of tasks in a workflow and the version number of the baseline is given whenever the workflow is created. Whenever any change happens, the version number of the task or baseline will be modified accordingly. Both version numbers of the baseline and the tasks are checked while the workflow is being processed, so that the user could notice any differences in the tasks or workflow and decides whether to use the newly changed workflow or to keep the old version. A JADE development platform was applied to develop a prototype system and the architecture was based on Workflow Management Coalition. A scenario was shown in this paper to verify the feasibility of this study, and the result showed that users can choose whether to use the modified workflow baseline or not, for any running processes. This approach increases the workflow flexibility for collaborative design projects.
Recycling Aspect of End-of Life Vehicles – Recovery of Components and Materials from ELVs
Authors: Chamier-Gliszczyński Norbert
Published: November 2010

This paper presents the issue of recycling of end-of life vehicles. The first stage of this paper covers a presentation of the recycling system of end-of life vehicles, where the modules of the recovery of components and materials from end-of life vehicle were extended. This stage consists in the modelling of the structure of the sets of components and materials to be recovered from ELV. The third stage is related to an analysis of the processes specified in the module of the disassembly process and the shredding process in the aspect of an analysis of the economic costs of their execution.
Study on Conveyor AMESim Model and Motor Starting Interval
Authors: Li Guang Bu , Ye Ru Yu , Li Ru Qiong
Published: November 2010

This paper sets up a model of belt conveyor driven by two drive pulleys and three motors based on AMESim. The starting performance of conveyor is studied in three cases of motor starting interval: without time interval, with three second interval, and with five second interval. The conclusion is as following: the longer the time interval, the smaller the impact on the belt, and the acceleration of belt and gravity take-up. The simulation design suggests that three second interval and dual gravity take-ups should be taken. And the output torque of drive system should be reduced by 8—15%.
A Dynamic Positioning Method for Single Point Mooring System of a Catamaran
Authors: Xue Kai , Wang Wen Bin , Wang Wei Yuan
Published: November 2010

The main purpose of this paper is to solve the yawing problem of a single point mooring catamaran which designed for some special offshore operations. Dynamic characteristics of mooring system had been analyzed with the effect of wind, wave and current in early research. The results show that the yawing motion would be occurred for that system and can not be avoided without external control methods. These results are supported by sea tests of the real catamaran. Then, an azimuth thruster, set aft the ship, is used for a simple dynamic positioning (DP) system of the catamaran. The system is not a complete DP system because only one freedom can be controlled for the horizontal plane motions of the catamaran. The yawing angle is selected as control variable to meet the design requirement. The thrust is perpendicular to the longitudinal axis of the ship and can provide a maximizing yaw motion for DP system. Proportional-derivative control law is applied and the feedback variables can be obtained by global positioning system in further practices. The control effectiveness is validated by numerical results and comparisons with the non-controlled situations.
Attenuation of Structurally Radiated Sound from an Elastic Cylindrical Shell by Local Vibration Control
Authors: Jin Guo Yong , Shi Shuang Xia , Liu Zhi Gang
Published: November 2010

This paper presents a numerical and experimental study on attenuation of structurally radiated sound from an elastic cylindrical shell by local vibration control. An analytical model is developed for the active structural acoustic control (ASAC) of the cylindrical shell. A local control strategy is considered by minimization of the mean-square velocity of finite discrete locations. Numerical simulations are performed to examine and analyze the control performance. Results show that global sound attenuation of the cylindrical shell can be obtained at resonance frequencies. However, control spillover may occur at off-resonance frequencies. Modal suppression and rearrangement mechanisms may be involved in the control process. ASAC experiment was implemented by FXLMS algorithm, good agreement was observed between the numerical and experimental results, and successful attenuation of radiated sound was achieved.
Numerical Analysis of Shock Responses for a Marine Gearbox System
Authors: Wang Wei Yuan , Xue Kai
Published: November 2010

Gearbox system, as the main component of the marine power plant, is the closed drive unit that connects the main engine to the shaft. The operation state of the gearbox system has great influence for the safety and reliability of the ship. Shock loading is one of the most common external excitation for the ship and often destroys the devices and structures. Then, according to a mass of numerical calculations, this investigation develops some parameterizations for shock responses of the marine gearbox. The system modeling procedure is based on 3D finite element method which considers the effects of transient dynamic, geometrical nonlinear and impact/contact problems. Typical shock loads, which have the shape of double peak and triangle wave, were applied alone the three perpendicular directions on the bottom surface of the gearbox system to simulate the process of base excitation. The load can be described by two parameters: amplitude and wave length. Responses of the system were calculated with different load parameters and the maximum deformations were taken out by using Von Mises yield criterion. The relationship between shock parameters and structure stress were finally expressed by simulation data curve.
Application Analysis of an Improved N-R Iterative Method about Finite Element Numerical Calculation
Authors: Zhang Ling Xin , Hu Ming Yi , Wu Ping Chuan
Published: November 2010

During the numerical calculation by FE (Finite Element) method, N-R (Newton-Raphson) iterative method will be used to solve the problem such that material performing with elasto-plastic character and geometric non-linearity. However, if the problem has macro scale DOFs (degree of freedom), the classical N-R method is shown to make a low efficiency on the whole process. For this reason, in this paper, an improved N-R iterative method is proposed by creating proper mandatory limiters to change the step size of displacement field increment. In this way, the size of single iterative step is enlarged in the new method with tangent stiffness matrix used as classical N-R iterative theory as well. Furthermore, to test stability of the new method, two models of structure are chosen to be calculated with this method. In the conclusion, the improved N-R iterative method is indicated to be an efficient and stable numerical method which could solve nonlinear problems, especially with macro scale DOFs.
An Integrated Fuzzy Multi-Attribute Decision-Making Methodology for Evaluation of Mechanical Product
Authors: Chen Yuan , Li Bing , Yang Xiao Jun
Published: November 2010

The concept evaluation of mechanical product is essentially a multi-attribute decision making (MADM) problem in the fuzzy environment. In order to reduce the adverse impact of preference or judgments of decision makers on the final evaluation results, this paper attempts to propose an integrated fuzzy multi-attribute decision making methodology that combines the fuzzy TOPSIS technique and the objective weighting to evaluate mechanical product. The fuzzy TOPSIS technique is applied to rank the design alternatives, and the objective weighting method is integrated into the fuzzy TOPSIS technique to determine the appropriate criteria weights. Finally, a real application to pan mechanism selection for a cooking robot is demonstrated.
Research on Tool Flow Deadlock Based on Petri Net and Graph Theory
Authors: Zhao Dan , Liu Shao Gang , Shu Hai Sheng
Published: November 2010

Part flow and tool flow were the two mainly aspects of the workflow in flexible manufacturing system. During the past decades part flow deadlock was much more considered than that of tool flow. Tool flow deadlock problem in the condition that the production procedure can be interrupted was studied in this paper. The model of machine process based on the Petri net was set up and the definition of tool flow deadlock was proposed. Necessary and sufficient conditions for deadlock and potential deadlock were discussed according to graph theory method. A case was illustrated and showed that this method was to be correct and effective.
Power Transmission of Two Coupled Rectangular Plates with Elastically Restrained Coupling Edge
Authors: Chen Yue Hua , Jin Guo Yong , Du Jing Tao , Liu Zhi Gang
Published: November 2010

A model of two coupled rectangular plates with elastically restrained coupling edge by using the Fourier series and Rayleigh-Ritz method is employed to analyze the power transmission and dynamic response, in which the flexural and in-plane vibrations are considered simultaneously. The contributions and effects of vibrational and internal force components of both flexural and in-plane vibration to the power transmission are investigated numerically. It is shown that the transverse shearing forces, twist moments and in-plane shearing forces have little influence on the power transmission, while the bending moments and the in-plane longitudinal forces play an important role in power transmission.
Multi-Objective Optimization Design for Cutting Head of Roadheader
Authors: Zhang Xin , Liu Xiao Zhe , Zhang Jian Wu , Zeng Qing Liang
Published: November 2010

Aiming at load fluctuations and energy consumption of cutting head, a novel optimization strategy is presented in this paper, which is making every pick loaded uniformly and keeping number of picks in cutting section constant at every moment. It also considers the coal compression-tension effect and the action of pick tilt angle to pick force. The mathematical model of multi-objective optimization design for pick arrangement parameters and motion parameters of cutting head is established firstly, and then the sequential quadratic programming method (SQP) is chosen to compile the program of optimization design. The optimization example shows that in the premise of outline dimensions of cutting head unchanged, the load torque fluctuation decreases for 92%, which reduces the torsional vibration of transmission system of roadheader effectively. The swing force fluctuation also decreases for 83%, which enhances the stability of swing feed. Although the mean value of cutting head’ load decreases a little, all the load peaks decline after optimization, which avoid the single pick overload. And, the specific energy consumption decreases for 21%, which improves the energy utilization of roadheader.
Lightweight Design for Hydraulic Support
Authors: Zhang Xin , Zhang Jian Wu , Zeng Qing Liang , Wang Cheng Long
Published: November 2010

In large inclined angle mining condition, in order to decrease the effect of sliding force, a lightweight design for hydraulic support is presented in this paper. Taking minimum mass of top beam as optimization objective, the three-dimensional model of it is built firstly. The whole top beam is simplified into top plate, side plate, bottom plate and main reinforcement on the premise of unchanging its topology configuration, and only strength constraint is chosen as constraint, which reduces the number of constraint functions and calculation cycles. By means of ANSYS zero-order optimization module, the mass of top beam is decreased about 16.9%. Finally, the optimal lightweight structure is fully evaluated under the same load as pre-optimization, and finite element analysis results prove that its stress and strain satisfy the need of strength. This lightweight design measure is used in the practical manufacturing with a lower cost of materials, which also increases the stability of hydraulic support in large inclined angle mining condition.
Charge Transport and Interfacial Charge Transfer in Dye-Sensitized Nanoporous Semiconductor Electrode Systems
Authors: Jennings James R. , Wang Qing
Published: November 2010

General characteristics of dye-sensitized nanoporous semiconductor electrode systems are summarized, with a particular emphasis on dye-sensitized solar cells. Properties of these electrode systems which distinguish them from conventional bulk semiconductor electrodes are highlighted. Current understanding of electron transport in dye-sensitized solar cells, in terms of the diffusion and multiple trapping models, is reviewed. Alternative transport and recombination theories are also briefly reviewed. Electron transfer at the semiconductor/electrolyte interface in dye-sensitized solar cells is reviewed and recent experimental results obtained by the authors are highlighted. As applicable, common techniques for characterization of electron transport and transfer in dye-sensitized solar cells are described, with reference to case studies where the electron diffusion length in dye-sensitized solar cells has been estimated. The steady-state aspects of the dye-regeneration process are also reviewed, together with the cross-surface percolation of holes in the dye monolayer and the finite-length diffusion of redox species in the electrolyte.
Creep Behaviour of Reinforced Masonry Walls by CFRP Sheets and Structural Mortar
Authors: Antonaci Paola , Bocca Pietro G. , Masera Davide
Published: November 2010

An experimental analysis on a set of strengthened masonry walls has been carried out by means of cyclic loading tests in order to simulate the creep effects. Laboratory tests were carried out at the Non-Destructive Testing Laboratory of the Politecnico di Torino: ad hoc brickwork specimens were manufactured and reinforced by FRP and strengthening mortar. The main goal of this experimental work is to demonstrate that in the choice of the masonry reinforcement is important to value not only the increment of the ultimate strength of the material reinforced, but also its response and durability in term of long-term action, called as creep phenomenon.
Study on Non-Local Damage Constitutive Model of Concrete under Freeze-Thaw Action
Authors: Liu Zong Min , Mao Ji Ze , Song Hai Yan
Published: November 2010

Concrete is multi-phase composites. Due to the inhomogeneity of mechanical properties
and complexity of physical properties, constitutive relations of concrete are more complicated.
Starting from irreversible thermodynamics theory, internal state variable theory and nonlocal field
theory, non-local damage constitutive model of concrete under freeze-thaw action is established in
this paper. In the model, non-local influence functions are discussed which are used to describe
interplay of damage between adjacent point.
Out-Plane Distortion Induced Fatigue Analysis of Steel Bridges
Authors: Wu Zhi Ping , Wang Chun Sheng , Cheng Feng
Published: November 2010

Induced forces in secondary steel bridge members such as diaphragms and cross-bracing can cause out-of-plane distortion in webs that may lead to fatigue cracking. Such cracking is most likely to occur if the distortion must be accommodated in a short length of the web, such as in the gap between the end of transverse stiffeners and girder flanges, because the web gap is subject to double curvature. In this paper, the numerical analysis model of a real 3-span continue steel bridge was established using ANSYS software to calculate the real fatigue stress at the web gaps. Some key structural parameters, for example, web gap depth and web thickness, have been considered in the numerical models. The results show that web thickness and web gap depth give the great affection on the out-of-plane distortion fatigue stress at web gaps.
Evaluation of Failure Behavior and Strength of Fractured Rock Sample Using In Situ Triaxial Compression Tests and Expanded Distinct Element Method
Authors: Li B. , Jiang Y.
Published: November 2010

The in-situ tests have been widely used to directly assess the strength and deformability of rock mass, along with which, various numerical approaches were proposed to give rational interpretations to the mechanical phenomenon happening during these tests. In this study, the so-called potential cracks are introduced into DEM model, leading to expanded DEM (EDEM) approach which is capable of simulating the cracking in intact rocks. The EDEM is applied to an in-situ triaixal compression test on a fractured rock sample. The simulation has well represented the failure mode, peak stress and elastic modulus obtained from tests as well as the cracking phenomenon and the slips on fracture planes during the loading process.
Effective Young’s Modulus of Spiral Accumulating Core Used for Permanent Magnet Motor
Authors: Takase Yasushi , Takada Hisataka , Noda Naoaki
Published: November 2010

Recently, permanent magnet motors are widely used in wide industrial fields because they are suitable for compact mechanical system. The motor core is usually manufactured from magnetic steel sheet with press machine. However, usually most parts of the plate are scalped, and only small percent of the sheet is used for the core. The spiral accumulating core system is suitable for manufacturing the core more ecologically because in this system more than 50% of the magnet steel sheet can be used. In this study, therefore, the effective Young’s modulus of the spiral accumulating core is considered in order to find out a good method to fix the core. In this analysis, effective Young’s modulus of spiral accumulating core used for permanent magnet motor is considered by the application of the finite element method to 3D models, whose layers and slits are periodically arranged. Then, effects of slits, layers and embossing interlockings on effective Young’s modulus are analyzed. Finally, a convenient method of calculation based on rule of mixture is newly proposed for estimating the effective Young’s modulus of the real spiral accumulating core.
Fatigue Damage Behavior Depending on the Bonding Interface Layer in Copper Film Bonded to Base Metals
Authors: Torii Tashiyuki , Ishida Koki , Hassan Mohamed K , Shimizu Kenichi
Published: November 2010

Laminated copper films of the epoxy-bonded or diffusion-bonded to the base metal were used in order to investigate and analyze film fatigue behavior depending on the inevitable bonding interfaces for electric/functional parts used in MEMS. Fatigue damage was observed using SEM and crack initiation lives were evaluated at the notch root where the bonding interfaces could be observed directly through the thickness. These observations showed that the resin interface layer caused cracks without slips in a zig-zig pattern and also decreased fatigue crack initiation lives. On the other hand, fatigue damage was observed using an optical microscope on surface of the film with resin bonding or with diffusion bonded interfaces. In this case, many cracks were caused and propagated towards the width direction on the film bonded to the base steel with resin, while slip and cracks were caused along slip lines during fatigue on the film bonded to the base steel by diffusion. There was a significant difference in crack initiation behavior of the films between resin and diffusion bonded to base metals. This finding was not only for crack initiation site but also for roughness near the crack on the film. Using Eulerian equation of motion in continuum, this difference was discussed in terms of elastic displacement field with a wave caused from the base plate subjected to cyclic deformation. Such a wave motion enables us to understand the geometric effects of bonding interfaces on the fatigue damage behavior of the bonded film to base metal.
Modelling Aeronautical Composite Laminates Behaviour under Impact Using a Saturation Damage and Delamination Continuous Material Model
Authors: Ilyas Muhammad , Espinosa Christine , Lachaud Frédéric , Michel Laurent , Salaün Michel
Published: November 2010

We show that the behavior of T700/M21s and T800/M21s composite panels are affected by the influence of strain rates together with local shear and crush punch or global flexural strengths of the structure. A deterministic continuous composite material model has been developed as a LS-DYNA user defined material model for unidirectional composites on the basis of the Matzenmiller model widely used for woven composites. Initiation and evolution up to saturation and fracture are implemented for various and coupled damage mechanisms including delamination. Quasi-static and dynamic characterization tests laminates have been carried out on balanced angle ply [±θ] and used for calibration of numerical values. Impact induced damage from experiment’s measures and numerical predictions are compared for T800/M21S aeronautical samples impacted at 15J.
Case Study of Crack Initiation from Bi-Material Notches
Authors: Klusák Jan , Knésl Zdeněk
Published: November 2010

Conditions of damage initiation in bi-material structures are analysed in the paper. The considerations are derived from the knowledge of the stress state caused by the existence of the sharp notch and the bi-material interface. The step change of material properties and the geometrical discontinuity at the interface leads to a singular peak of stress that is similar to the stress singularity near the crack tip in homogeneous material. That fact urges to use generalized linear elastic fracture mechanics for assessment of conditions of crack initiation. In the paper crack initiation direction and quantification of the external load connected with crack initiation are discussed. Within the stability assessment, possible directions of crack initiation should be considered and tested in both material components and at their interface as well. Knowing the critical applied stresses, one can decide among the damage eventualities.
Wave Radiation from a Stick-Slip-Like Moving Source
Authors: Watanabe Kazumi
Published: November 2010

Waves generated by a moving source are discussed. Introducing a simple model for the stick-slip motion of the source, an exact response of SH-wave in an infinite elastic solid is derived. The response is composed of an infinite sum of time-harmonic wave with multiple frequency of the stick-slip motion and Doppler effects are derived from the far-field approximation. This shows that Doppler effects take place even if the source magnitude is uniform, not time-harmonic.
Fracture Properties of PCBN as a Function of Loading Rate and Temperature
Authors: Carolan Declan , Petrović Marin , Ivanković Alojz , Murphy Neal
Published: November 2010

Polycrystalline Cubic Boron Nitride (PCBN) is a super-hard material used in some of the most demanding material removal operations today. These include turning of hardened steels, as well as the machining of highly abrasive alloys. In these applications the tools are subjected to high operating temperatures, abrasive and impact loading. This can lead to the brittle fracture of the tool. Accurate determination of the fracture toughness and mechanical properties of PCBN under a wide range of operating conditions is therefore essential in order to evaluate the performance of the tool under these highly demanding conditions. For this study, a laboratory scale three point bend test rig has been used for the fracture tests. The fracture toughness of two different grades of PCBN are measured at a range of loading rates and temperatures corresponding to the actual in-service conditions. The results show the measured properties of these materials vary with both loading rate and temperature. The fracture surfaces of the specimens are examined using scanning electron microscopy to determine dominant fracture mechanisms.
Fatigue Crack Growth in Adhesively Bonded Joints with Intermittent Impacts
Authors: Ashcroft Ian A. , Casas-Rodriguez Juan Pablo , Silberschmidt Vadim V.
Published: November 2010

The use of structural adhesive joints to join carbon fibre reinforced polymer (CFRP) adherends is now well established in the aerospace industry. These joints are subjected to varied load spectra, of which one of the most damaging forms of loading is fatigue with intermittent low energy impacts, which is termed combined standard and impact fatigue (CISF) in this paper. It is seen that the rate of crack growth in impact fatigue is greater than that in standard fatigue for a given value of the strain energy release rate, moreover, it is seen that the fatigue crack growth rate (FCGR) in standard fatigue (SF) increases after a block of impact fatigue. In this paper a model is proposed to predict crack growth in bonded joints subjected to CISF. The model is based on numerical crack growth integration (NCGI) with a method of accounting for the accelerated crack growth in SF following IF. The model was seen to provide a good prediction of the fatigue crack growth in CISF.
Study on Long-Term Expansive Deformation of Self-Stressing Concrete with Combined Restrictions of Steel Fibers and Steel Bar
Authors: He Huan An , Dong Wei , Wu Zhi Min
Published: November 2010

Self-stressing concrete is sort of expansive concrete with high expansion energy which can induce prestresses with restriction in concrete, and steel fibers also enhance tensile strength of concrete. The combination of these two high performance concrete can be used to improve the cracking resistance of concrete significantly. However, like mechanical prestressed concrete, a stable long-term prestresses (self-stresses) level is a key to exploit the particular advantage of steel fiber reinforced self-stressing concrete. Self-stresses are created by restricting the expansion of self-stressing concrete with steel bars or/and steel fibers, therefore, in this paper a series of tests on long-term expansive deformation of concrete were carried out by means of measuring restrict expansive deformation of self-stressing concrete with restriction of steel fibers. The results of tests showed, based on the three-year recording, that the expansive deformation of steel fiber reinforced self-stressing concrete almost kept the same as that of 28-day without remarkable rebound which indicated that losses of self-stresses were not significant and can meet the design requirements on self-stresses level. In addition, it is proposed on the relationship between restrict expansive deformation and reinforcement ratio of steel rebars under different steel fiber volume fraction from 0-2%.
A Variational Meshless Method for Mixed-Mode Fracture Problems
Authors: Wen P.H. , M.H.Aliabadi Ferri
Published: November 2010

A variational technique has been developed to evaluate the static stress intensity factors of mixed mode problems with mesh free method in this paper. The stiffness is evaluated by regular domain integrals and shape functions are determined by both radial basis function (RBF) interpolation and moving least-square (MLS) method. The stress intensity factors are obtained by two boundary integrals with variation of crack length. The applications of proposed technique to two-dimensional fracture mechanics have been presented with several examples. Comparisons are made with benchmark solutions.
Suppression of Fatigue Crack Growth in Austenite Stainless Steel by Cavitation Peening
Authors: Takakuwa Osamu , Nishikawa Masaaki , Soyama Hitoshi
Published: November 2010

Cavitation normally causes severe damage in hydraulic machinery such as pumps and turbines by the impact produced by cavitation bubbles collapsing. Although cavitation is known as a factor of erosion, Soyama et al. succeeded in utilizing impacts of cavitation bubble collapsing for surface modification by controlling cavitating jet in the same way as shot peening. The local plastic deformation caused by cavitation impact enhances the fatigue strength of metallic materials, and the surface modification technique utilizing cavitation impact is called “cavitation peening (CP)”. It is well known that the peening improves fatigue strength by introducing compressive residual stress on the surface, but little attention has been paid to the behavior of fatigue crack growth of the material which was modified by CP. In the present study, the fatigue behavior of austenite stainless steel with and without CP was evaluated by a plate bending fatigue test, and the results revealed that the compressive residual stress introduced by CP suppresses fatigue crack growth rate by 70 % compared to that without CP.
3D Lattice Fracture Model: Application to Cement Paste at Microscale
Authors: Qian Z. , Ye Guang , Schlangen Erik , van Breugel Klaas
Published: November 2010

The fracture processes in cement paste at microscale are simulated by the 3D lattice fracture model based on the microstructure of hydrating cement paste. The uniaxial tensile test simulation is carried out to obtain the load-displacement diagram and microcracks propagation for a Portland cement paste specimen in the size of 100×100×100 µm3 at the degree of hydration 69%. The Young's modulus, tensile strength, strain at peak load and fracture energy are computed on the basis of the load-displacement diagram.
The Experimental Study on Fracture and Damage Mechanism of RC T-Beam
Authors: Zhou Mi , Zhang Yue
Published: November 2010

In order to research the stiffness degradation mechanism of RC T-beam under the condition of different damage and get the influence law of damage degree on dynamic characteristics of single beam, the dilapidated static and dynamic test on four pieces of RC simple T-beams is explained in the paper. Under different degree of damage these parameters of four pieces of RC simple T-beams with two kinds of reinforcement ratio, such as crack, mid-span deflection, basic frequency, dynamic stiffness, static stiffness are measured. The frequency and stiffness variation of RC T-beam is obtained. The functional relationships of T-beam between ratio of static stiffness to dynamic stiffness and load ratio , the frequency ratio and load ratio were established. Furthermore the numerical simulation calculation on test results is made by the finite element analysis. According to the above research, the damage mechanism and frequency variation of RC T-beam under vertical load are summarized.
Giga-Cycle Fatigue Behavior of Notched Specimens for High Speed Steel
Authors: Ebara Ryuichiro , Nakamoto K. , Ogura A. , Ishihara Y. , Hamaya S.
Published: November 2010

Giga-cycle fatigue behavior of notched specimens with stress concentration factor, Kt of
1.5, 2.0 and 2.5 for 0.65 mass% carbon matrix high speed steel, YXR3 with Rockwell C scale
hardness number of 60.7 is investigated. The higher the stress concentration factor the lower the
giga-cycle fatigue strength is. The emphasis is placed upon the subsurface crack initiation observed
on all notched specimens. Crack initiation mode of high speed steel is discussed with respect to
fracture surface morphology.
In Situ Observation of Crack Propagation in Epoxy Composite Reinforced with Crushed Silica Particles
Authors: Boonyapookana Alisa , Mutoh Yoshiharu , Nagata Kohsoku
Published: November 2010

In-situ observation of fatigue crack growth of epoxy resin composite reinforced with crushed silica particle was carried out. The test was performed under constant ΔK condition. Based on the results, the crack propagation mechanism was discussed. The in-situ observation revealed that in front of the main crack, a microcrack was nucleated at the interface of matrix/particle and then coalesced with the main crack. At the same time, new microcracking occurred ahead of the crack tip and the crack propagated by repeating these processes. Retardation of crack growth rate was found to result from crack bridging induced by microcracking at silica particles and crack deflection.
A Comparison of CMOD-Based CTOD and J-Conversion CTOD in Shallow Crack Specimens
Authors: Kayamori Yoichi , Inoue Takehiro , Tagawa Tetsuya
Published: November 2010

The ratio of J-conversion CTOD to CMOD-based CTOD was experimentally evaluated and analytically estimated in shallow crack specimens. It was demonstrated that the low strain hardening exponent in the Ramberg-Osgood relation reduced the CTOD ratio. A CTOD transformation equation, which was proposed by the authors, can transform CMOD-based CTOD into J-conversion CTOD with reasonable accuracy for 0.15≤a/W≤0.5.
Numerical Analysis of the Effect of Added Hole on the Stress Concentration of a Perforated Plate and Determining of Its Optimum Location
Authors: Khoshravan Mohammad Reza , Khalili A. , Razavi M.J.
Published: November 2010

The aim of this work was to investigate Stress Concentration Factor (SCF) variations induced by adding of holes in a perforated base plate subjected to uniaxial tension load, using Finite Element Method (FEM). Analyses were applied in 2D for different diameters, orientation angels and distances of added holes from the base hole. A parametric model in ANSYS finite element software was used to calculate the SCFs and the differences between SCFs have been shown in various graphs. To investigate the variation of SCF in perforated base plate, two holes with the same diameter were located symmetrically to the longitudinal axis with different angles and distances from the base hole. The results showed that by adding holes with a proper diameter, orientation angles and distances from the base hole, the SCFs can be reduced. Using the obtained graphs and corresponding to the base hole diameter the most adequate diameter and its position was determined. Obtained results for special statuses had a good agreement with the graphs of Peterson’s stress concentration factors.
Modeling Fracturing in Rock Using a Modified Discrete Element Method with Plasticity
Authors: Alassi Haitham , Holt Rune
Published: November 2010

In this contribution we present more developments in the modified discrete element approach (MDEM) which was proposed to model fractures propagation in reservoir rock during production and fluid injection. The new development in this paper includes adding plasticity which allows the material to go into plastic deformation before initiating fractures. Several numerical tests are performed which mimic the real lab tests usually perform on rock samples, this includes direct tension test with initial crack to model crack propagation, and several biaxial compression tests to model the development of shear bands.
Numerical Simulation of Rubber-to-Steel Bimaterial Bonded Interface Cracking Based on Cohesive Element
Authors: Liu Xiao Ying , Yang Xiao Xiang , Wang Xiu Rong
Published: November 2010

Presented herein is a finite element investigation into the damage mechanism of the adhesive interface of the rubber-steel bimaterial. The cohesive element layer is used at the interface to simulate the initial loading, initiation and propagation of the damage. From the simulation results, it is found that interface strength exert significant effects on the crack formation in the interface. Smaller interface strength could lead to crack initiation more easily.
Analysis Method of Crack Propagation Data by Genetic Algorithms
Authors: Grasso Marzio , Penta F. , Pinto Paolo , Pucillo G. P.
Published: November 2010

A practice for analyzing some raw data from fatigue crack growth tests, carried out on specimens obtained from a railway component (wheel), is presented. Despite the data sample is small, it allows to identify the material parameters of the “threshold” propagation model that make this latter amazingly realistic for the examined material. The proposed analysis method is based on the Evolutionary Algorithms theory and uses raw data obtained from C(T) specimens instrumented with crack gauges.
Anisotropic Plastic Deformation and Damage in Commercial Al 2198 T8 Sheet Metal
Authors: Steglich Dirk , Wafai Husam , Besson Jacques
Published: November 2010

Deformation anisotropy of sheet aluminium alloy 2198 (Al-Cu-Li) has been investigated by means of mechanical testing of notched specimens and Kahn-type fracture specimens, loaded in the rolling direction (L) or in the transverse direction (T). Contributions to failure are identified as growth of initial voids accompanied by a significant nucleation of a second population of cavities and transgranular failure. A model based on the Gurson-Tvergaard-Needleman (GTN) approach of porous metal plasticity incorporating isotropic voids, direction-dependent void growth, void nucleation at a second population of inclusions and triaxiality-dependent void coalescence has been used to predict the mechanical response of test samples. The model has been successfully used to describe and predict the direction-dependent deformation behaviour, crack propagation and, in particular, toughness anisotropy.
Towards Chemical Mapping at Sub-Micron Resolution: Near-Field Spectroscopic Delineation of Interphase Boundaries
Authors: Pollock Hubert
Published: November 2010

Several of the authors of this collection of papers presented at the international meeting on the mechanical behaviour of materials have been working continuously in that field for several decades. In contrast, in this instance we have an example of an author who, having some experience in nanoindentation and surface - mechanical research, now pursues interdisciplinary studies of nanoscale properties in a different field. This paper discusses how a near-field version of infrared microspectroscopy, together with multivariate data analysis points a way towards a new method for identifying biomarkers for use in biomedical evaluation procedures. We also outline some details of a non-statistical method of classification, employing fuzzy logic.