bluuebunny/crossref_metadata_2025 huggingface dataset:
Microscintillator of Ce Doped β-NaLuF4 in Uniform Hexagonal Prism Morphology by a Facile Hydrothermal Method
Authors: Liu Li Sha , Chen Hao Hong , Liu Bi Qiu , Tang Bin , Sun Zhi Jia , Zhao Jing Tai
Published: March 2014

To explore micro-or nanoscintillator with a controllable architecture, a novel facile hydrothermal method easy for commercial run was used to synthesize pure and Ce doped β-NaLuF4 microcrystals at 453K. The morphology of uniform hexagonal prism with 3.3μm in diameter and 1.4 μm in thickness, respectively, is presented by the results of scanning electron microscopy (SEM). Powder X-ray diffraction (PXRD) patterns show the products are both pure hexagonal phase. Different from the undoped product without any irradiation, the Ce doped product has given strong broad band emission attributed to 5d4f transition of Ce3+, which can be potentially used as scintillator for biomedical imaging and detectors for high energy such as X-ray and γray. This synthetical strategy extends the understanding about nanomaterial chemistry and can be also useful for other systems such as fluorides, oxides and sulfides.
Investigation of Blends of sPS/B30, B30/iPP and sPS/iPP/B30: Mechanical and Thermal Properties
Authors: Yang Xiao Yu , Wu Xin Hua , Zhao Yang Feng , Huang Qi Gu
Published: March 2014

The mechanical and thermal properties of B30/iPP, B30/sPS and sPS/iPP/B30 blends were investigated by unnotched izod impact tester, DSC and tensile strength tester. The results showed that the mechanical properties of B30/iPP, B30/sPS and sPS/iPP/B30 blends were better than that of homopolymer B30 and sPS. The blend of sPS/B30 with the ratio of 80/20, unnotched izod impact strength was 41.2 KJ/m2, tensile strength 32.5 MPa. The blend of B30/iPP with the ratio of 90 to 10, the unnotched izod impact strength was 46.2 KJ/m2 and the tensile strength 27.2 MPa; and the blend of sPS/iPP/B30 with the ratio of 90/10/10, the unnotched izod impact strength was 42.3 KJ/m2, and the tensile strength 33.7 MPa. DSC result showed that in the blend system of B30/iPP and sPS/iPP/B30 the iPP-Tg region shifted toward the sPS-Tg. However, the sPS-Tg shifted inward slightly.
Mechanical Analysis for Thin-Walled Stiffened Plates on the Base of Plants Venations Growth Algorithm
Authors: Wang Wei Yuan , Li Yuan Yuan , Wang Ping
Published: March 2014

The reinforced shin shell structures are widely used in many fields such as mechanical, architecture, aerospace and shipbuilding, etc. The leaf can be seen as shin plate structures with stiffener (vein) and the venation distributions are closed related to the external environment load. Leaf venation growing algorithm is the abstract description of vein growing process and reflects an ideological of learning from nature. This article concerns the mechanical analysis for thin-walled stiffened plates, which consist of static mechanical behavior and dynamic performance. Numerical method is used to analyze three types of plants: non-stiffened plate, traditional stiffened plate and stiffened plate optimized by leaf venations growth algorithm (VGA) method. The calculation results proved that the VGA stiffened plate has better mechanical performances than traditional method and illustrated the effectiveness of the bionic venations layout method for stiffened structures.
Comparative Study of Squeeze Casting of AA6061 with and without Employing Ultrasonic Cavitations
Authors: Azhagan M. Thirumal , Mohan B. , Rajadurai A.
Published: March 2014

The automotive and aerospace industries have been the main driving force behind the search of new production processes which are capable of producing components with high integrity. Squeeze casting is one such novel metal processing technique which combines the advantages of both casting and forging in one operation. Squeeze casting process is suited for all melting ranges of metals varying from lead to iron. But nowadays, light weight materials like aluminium and magnesium are mostly used in the above mentioned industries. Aluminium alloy 6061 is one such futuristic material that is widely employed to produce automotive and aerospace components. In this research two sets of cylindrical components of AA6061 were produced through squeeze casting where the first set of components was produced without employing ultrasonic cavitations and the second set of components was produced by employing ultrasonic cavitations and the components were tested for tensile strength and hardness respectively. It was observed that the values of tensile strength and hardness exhibited by the components produced using ultrasonic cavitations were higher when compared to the values exhibited by the components produced without employing ultrasonic cavitations.
Experimental Investigations on the Effect of Vegetable Based Cutting Fluid in Turning AISI 1040 Steel
Authors: Jhodkar Durwesh , Amaranth M. , Chelladurai H. , Ramkumar J.
Published: March 2014

Application of petroleum based cutting fluids in machining operation may cause many problems such as eye burn and skin inflation etc. Vegetables oils are good alternative to overcome such issues. In this work, experiments were carried out to study the influence of coconut oil on the performance of single point cutting tool insert in turning operation. Three cutting conditions viz. dry, wet and coconut oil were considered to evaluate the tool wear. Results obtained from the experiments highlighted the advantages of coconut oil, a considerable reduction in flank wear, crater wear and auxiliary wear was observed in the turning operation.
Experimental Study on Superficial Modification of Recycled Aggregate with Fly Ash
Authors: Wang Fu Xing , Li Guo Zhong , Chen Juan
Published: March 2014

A modification of using fly ash grout of different levels was adapted to treat the surface of recycled fine aggregate (RFA).The physical properties of RFA before and after modification and the effect on the mechanical performance of cement mortar was studied.The result indicated that the modification of RFA could strengthen the enhancement effect on mechanical performance when modified by 15wt% fly ash grout. After modification, water absorption of RFA was 6.12% and decreased by 47.5%. The 28d flexural strength was increased by 17.4% and compressive strength was increased by 24.2% of RFA cement mortar compared with the reference samples. The superficial microstructure and sectional morphology of RFA was observed by scanning electron microscopy (SEM). The modification mechanism was carried out.
Microbial Oil Production from Lignocellulosic Biomass – Recent Development and Prospect
Authors: Lin Zhang Nan , Liu Hong Juan , Wang Zhi Qin , Zhang Jia Nan
Published: March 2014

Microbial oil is one of the ideal raw materials for biodiesel production because of its rapid reproduction and less influence by the climate and season variation. However, the high cost is one of the key issues that restricted its production in a large-scale. Lignocellulosic biomass, the cheap and renewable resource, might be the best raw material for microbial oil production by oleaginous microorganisms. Recent development on the microbial oil production from lignocellulosic biomass was summarized in this paper. Furthermore, the challenges and application potential of microbial oil were prospected.
Investigation of the Solubility and Absorption Rate of CO2 in PZ Promoted K2CO3 Aqueous Solution
Authors: Zhao Shu Bin , Liu Feng , Wu Xiang Cheng , Fu Dong
Published: March 2014

The solubility and absorption rate of CO2 in piperazine (PZ) promoted potassium carbonate (K2CO3) aqueous solution were measured at 1 atm. The temperatures ranged from 328.15 to 343.15K. The mass fractions of K2CO3 (w1) and PZ (w2) respectively ranged from 0.2 to 0.25, and 0 to 0.05. The influence of the mass fractions of PZ on the solubility, CO2 loading and absorption rate was illustrated.
Winding Trajectory Generation for Composite Products
Authors: Fu Jian Hui , Yun Jae Deuk , Jung Yoong Ho
Published: March 2014

We generate geodesic or nongeodesic trajectories for filament winding based on the StereoLithography model. The discrete trajectory is traced out by constantly appending a new propagation point determined from the two most recent points of the path. According to differential geometry and discrete geometry theory, nonslippage and nonbridging conditions are added to constrain the propagation point to obtain a stable winding trajectory. This method can be applied to any convex surface, either axisymmetric or nonaxisymmetric shapes. An application for pressure vessels is implemented to validate the feasibility.
Driveline Simulation of 2013 Formula Student Electric Racing Vehicle
Authors: Li Yun Long , Kley Markus , Wang Shi Jie
Published: March 2014

The chief aim of this present work is to simulate a driveline of 2013 Formula Student electric race vehicle, in order to support the E-Motion Team (Aalen University, Germany) which will be attend to the race competition in Italy, to give previous results and also improving advises for next formula student generation. Due to the four competition events and powertrain system have been obtained, therefore the objective of this article is firstly to describe every detail of the driveline and different rules for every competition event, consequently researching the transmission calculation which is according to critical factors will be done during the second step. Furthermore with editing and loading the parameter into WINEVA programming, all the required simulation motion results were achieved. Moreover by changing different loading parameters, several critical factors will be pointed out. Finally based on the simulation results, some design and driving advises will be proposed for the next vehicle generation.
Study on Effect of the Ternary Composite Retarder on Properties of FGD Gypsum Plaster Material
Authors: Li Xiao Long , Li Guo Zhong , Liu Yu Zong , Su Deng Cheng
Published: March 2014

Each component ratio of the ternary composite retarder was determined through orthogonal test and the effect of the ternary composite retarder on physical properties of FGD gypsum plaster material was studied. The results show that when the dosage of citric acid, admixture 1, admixture 2 were 0.05%, 0.4% and 0.3% respectively in the ternary composite retarder, the FGD gypsum plaster material had the best physical properties. The initial setting time was 118min and the final setting time was 132min respectively. The flexural and compressive strength were 3.15MPa and 6.46MPa, respectively. The microstructure of FGD gypsum hydration products was analyzed by SEM and the action mechanism of the ternary composite retarder was analyzed.
Design and Analysis of UHF RFID Tag Antenna on the Surface of Cylinder
Authors: Duan Pu Yu , Wang Dong
Published: March 2014

Cylinder is a common object and used in logistics industry, such as liquid container like wine. The performance of tags that are used on these objects declines, especially the read range and the radiation pattern of the tag. In this paper, a type of UHF tag antenna directly mountable on the cylinder surface. In order to reduce the impact of the deformation, the tag is designed with meander-line but not symmetrical. Antenna is combined with T-matching network to ensure good impedance matching. Compared with the basic dipole antenna tag both cylinder and plane surface, we can get the prominent feature of the tag proposed in this paper.
Design Sheet Beam Gun for THz Traveling-Wave Tube
Authors: Wang Zhan Liang , Gong Yu Bin , Gong Hua Rong , Feng Jin Jun , Xu Xiong
Published: March 2014

The Sheet Electron Beam Vacuum Electron Device is an Attractive Choice for Generating High Power Millimeter/terahertz Wave Radiation. the Sheet Electron Beam Gun is a Key Component for the Sheet Beam Vacuum Electron Device. in this Paper, a Novel Sheet Electron Beam Gun was Proposed for a Terahertz Traveling-Wave Tube. the Theories of Sheet Beam Gun are Deduced Based on the Round Beam Gun Theories. the Track of 24.5kV, 1A, 0.4mm8mm Sheet Beam is Gained through 3D Particle-in-Cell Simulation and the Theories are Verified. the Investigation Results Show that, the Design Method of the Sheet Beam Gun is Easy and Reliable.
A Fast Digital 3D-SVPWM Algorithm for Four-Leg Converter
Authors: Song Peng Xian , Wang Ping , Li Yao Hua
Published: March 2014

The three-phase four-leg converter can be obtained by adding a bridge into the traditional three-phase three-leg converter. The average mathematical model of three-phase four-leg converter is described in this paper. The three-dimensional space vector PWM (3D-SVPWM) is analyzed. For simplifying the modulation, a fast digital SVPWM algorithm which eliminates coordinate transformation and saves calculating time was proposed. The feasibility of the proposed modulation technique is verified by computer simulation. These results show that the proposed fast digital 3D-SVPWM technique can be easily implemented without conventional computational burden.
The Floquet Analysis of Liquid Interface Wave in a Double-Frequency Excited Cylindrical Container
Authors: Chang Long , Jian Yong Jun , Sun Yan Jun , Su Jie , Liu Quan Sheng
Published: March 2014

In generally cylindrical container, by the method of separation of variables solve the Laplace equation and linearized boundary conditions and obtain amplitude equation of double-frequency excitation fluid interface waves considering surface tension effects. We use double-layer single-frequency viscous fluid damping coefficient to modify the amplitude equation, and then analyze the instability of the new amplitude equation using Floquet theory. By numerical calculation, the instability region determined by different depths, excitation frequency, excitation amplitude, relatively amplitude factor, the phase difference and the surface tension is given. Moreover, the double-frequency excitation spectrum of double critical phenomena is also discussed.
Many-to-Many Regression Analysis of Loading Characteristic in Dieless Tube Hydroforming
Authors: Tian Zhong Ke , Yang Fa He , Yin Chao
Published: March 2014

Based on uniform design, finite element simulation of dieless tube hydroforming and double-screening stepwise regression method, a many-to-many polynomial regression equation set was established, whose independent variables are time t1 at which axial compression displacement from 0 reaches 25mm and time t2 at which internal pressure from 0 achieves 65MPa in 60 seconds, while dependent variables are hoop plastic strain s11 and radial plastic strain s22 in the midmost position of hydroformed tube. Analysis of partial correlation coefficient indicates that the effect of t2 on s11 is a little stronger than t1 and there is no interaction between t1 and t2 on s11, while s22 is influenced by t22 and t1t22. The many-to-many regression model not only quantificationally describes the action of loading factors on plastic strains but also reflects the inherent relevance between plastic strains, which is more useful than several one-to-many regression models to solve problems such as loading characteristic analysis, loading parameters design and optimization, etc.
Experimental and Numerical Investigation of Circular Arc Dovetail Attachments under Fatigue Loading
Authors: Shi Liang , Wei Da Sheng , Wang Yan Rong
Published: March 2014

Fretting fatigue is an important failure mode of dovetail attachments in gas turbine engines. One of the most difficult challenges in carrying out experiments of components with actual geometry is the design of fixtures for the dovetail attachments since it can change the stress distribution under a given load. A circular arc dovetail attachment specimen with a tenon at each end respectively was designed and machined to simulate the fatigue damage that occurs in wide-chord fan blade attachments, so it can perform two dovetail attachment simulations at each time, and its related fixture was connected with the testing machine by two pins which were orthogonal to each other so as to eliminate additional bending moment. An Instron 8802 servo-hydraulic fatigue testing system was used to provide fatigue loads. Furthermore, Finite Element (FE) analysis based on the experimental configuration was carried out to obtain the stress distribution on the contact surface, crack initiation location and number of cycles to the fretting fatigue failure were predicted based on the FE results. The results show a good agreement with the experimental counterparts.
Experimental Investigation of Vibration Characteristics for Vapor Cavitation in Plain Journal Bearing
Authors: Yusof Rosli Hj , Idris Ibrahim
Published: March 2014

The phenomenon of lubricant cavitation in hydrodynamic bearings and its detrimental effects have been documented in many literatures. Collapse of
vapor cavitation bubbles may cause erosion wear that limits the life of the bearings. The ability to detect the occurrence of vapor cavitation using a well established condition monitoring technique is essential for the equipment operator. An experiment was conducted to investigate the vibration characteristics of vapor cavitation in steadily loaded plain journal bearings. Vibration data were collected from the bearings operating under the influence of vapor cavitation. It is shown that, vapor cavitation exhibits distinct characteristics on the vibration plots. Low amplitude, forward and reverse 0.063X frequency components, and a series of harmonics with frequencies lower than 0.5X, are observed on the full spectrum. A unique waveform with the positive peak amplitude fluctuating above and below the zero axis line is also observed.
The Performance of TFC Slider under Second-Order Discontinuous Boundary Conditions
Authors: Ao Hong Rui , Pan Deng , Dong Ming , Jiang Hong Yuan
Published: March 2014

In this paper, the performance of TFC slider under second-order discontinuous boundary condition was studied. A new heat transfer coefficient under this condition according to micro/nanoheat transfer theory was deduced, and the heat transfer model on the air bearing surface was established. Using the finite element method, the differences of temperature, deformation and flying-height of TFC slider under continuous and discontinuous boundary conditions were compared and analyzed. The results show that consideration of discontinuous boundary condition is critical to the simulaiton accuracy of the heat transfer at air bearing surface.
The Numerical Analysis of the Velocity and Pressure Distribution of the Oil Film in Heavy Hydrostatic Thrust Bearing
Authors: Li Jian , Chen Yuan , Yu Yang Chun , Tian Zhu Xin , Huang Yu
Published: March 2014

To study the velocity and pressure distribution of the oil film in a heavy hydrostatic thrust bearing, a mathematical model of the velocity is proposed and the finite volume method (FVM) has been used to simulate the flow field under different working conditions. Some pressure experiments were carried out and the results verified the correctness of the simulation. It is concluded that the pressure distribution varies small under different rotation speed when the surface load on the workbench is constant. But the velocity of the oil film is influenced greatly by the rotation speed. When the rotation speed of the workbench is as quick as enough, the velocity of the oil film on one radial side of the pad will be zero, that is to say the lubrication oil will be drained from the other three sides of the recess.
Dynamic Simulation of the Stack-Manipulator to Aluminum-Ingot Based on ADAMS
Authors: Xu Da Wei , Wu Hai Tao , Liu Hong Bin , Cai Jia Cheng , Yao Tian Chang
Published: March 2014

On the research and development of the Stack-Manipulator to Aluminum-Ingot, the Stack-Manipulator 3D model was established by using SolidWorks and imported into ADAMS via the interface between them. And then the authors got the torque and angular velocity curves after adding the driving and constraints. Finally, this paper chose the servo motors by using the simulated results. The results provide a reliable and scientific basis for the development of the control system.
Modeling and Simulation of Wire Electrode Deflection in WEDM
Authors: Chen Zhi , Li He , Huang Yu , Zhang Zhen
Published: March 2014

In the process of wire electrical discharge machining, the wire electrode inevitably suffers bending deformation due to wire tension, electrostatic force, electrodynamics force, etc., and the deflection would make an clearly negative impact upon the machining accuracy, productivity and stability. In this paper, first of all, a novel modeling and simulation method is proposed for quantitatively calculating the wire deflection. Secondly, the mainly impact factors and trend of wire deflection have been concluded. Moreover, the feasibility of the model is proved by comparing with other researchers models. Eventually, the practical approaches of reducing wire deflection and improving the machining accuracy have been proposed.
Study on Development of a Urea-SCR System of Diesel Engine
Authors: Qiu Tao , Li Xu Chu , Peng Jing , Lei Yan , Yue Guang Zhao
Published: March 2014

Aimed at the diesel engine, a selective catalytic reduction (SCR) system was developed. In this system, the urea pump is integrated with a urea tank, air and urea mix in the injector, catalyst convertor is based on vanadium. Combining with a self-developed control unit, the urea-SCR system was tested on the engine bench. The ESC experiment results indicate that the NOx emission can be reduced effectively which meets the China stage IV regulation.
The Design and Research of Automatic Charging Parking Space
Authors: Sun Wan Chao
Published: March 2014

Chaotic management of the roadside parking causes traffic jams. The design and research of charge parking space automatically has been done in order to achieve the unmanned management roadside parking. The automatic charging parking space is mainly composed of translation guide rail, telescopic boom, solid tire part and control module; the device with high efficiency, security and stability is fully automatic. Based on different location, it has obvious effect to ease traffic pressure through the standard management.
Simulation of TBM Mucking Process Based on the Ballast Fluidity
Authors: Huo Jun Zhou , Chen Wei , Ouyang Xiang Yu , Zhang Xu
Published: March 2014

Cutterhead is the key part of full-face rock tunnel boring machine (TBM), the design method of mucking slot of TBM is directly related to its tunneling efficiency. In this paper, the coupling model of ballast and mucking structure of TBM is built used the discrete element method (DEM), and the simulation of TBM discharge ballast is made by PFC3D discrete element software. The simulation results show that, the number of particles generated is larger than the eliminated ones at the beginning of the mucking process, but with the change of time, the difference between the numbers of generated and eliminated particles is gradually reduced; the fluctuation of the number of particles within cutterhead is progressively smaller until it becomes stabilized, it fluctuates around the mean and the amplitude of fluctuation is no more than 100. The results in this paper can provide technical support for engineers.
Finite Element Analysis of a Mud Pump Damming Machine Frame
Authors: Sun Jun Yuan , Xiao Ji Ming
Published: March 2014

The mud pump damming technology is a new idea put forward for the realization of the warping dams constructed mechanization and automation. The mud pump damming machine is researched and developed. The FEA model of the machine frame is built. The deformation state, stress distribution, natural frequencies, mode shapes and also the biggest stress under loading the exciting force are obtained by processing the static analysis, modal analysis and harmonic analysis. The results show that the mud pump damming machine can basically meet the design requirements, while the vibrating screen driving motor should be improved to adjust its working frequency to avoid severe vibration, and the welding quality should be ensured to increase its service life.
Study on the Practical Connection Mode of Microgrid Adapting to Dual Power Supply
Authors: Yang Bin , Cao Zhe , Bao Hai Long , Yuan Zhi Qiang
Published: March 2014

Microgrid is one of the most important contents of smart distribution network, and also the most effective way to converting the distributed generation into full efficiency. The connection mode of microgrid has to suite for the traditional distribution network, and also has its own characteristics. This paper discusses the principles of choosing the connection mode for microgrid, analyzes three connection modes meeting the requirements of dual power supply, and puts forwards suitable connection modes and operating modes for Chenjiazhen microgrid.
Present Situation of Exploitation and Utilization of Geothermal Resources in China
Authors: Liu Hong Bin , Shi Yong Sheng , Zhang Lei , Qiu Ming
Published: March 2014

Geothermal energy provides the renewable energy sector with an opportunity to produce base load power, whilst meeting current government objectives of many countries in relation to greenhouse gas emission and renewable energy portfolio standards. The utilization of geothermal power develops well in many developed countries, such as America, Japan, France, Italy, Iceland, etc. But it is still at an early stage in China. The development of alternative energy such as geothermal energy is as a basic national policy. It is also an important issue for China how to make good use of geothermal resource currently. In this paper, according to the distribution, we introduce the development and utilization of Chinese geothermal resources.
Safety Study of Primary Loop System of Civil Marine Nuclear Power Plant
Authors: Xu Li , Deng Ru Chao , Xu Chu , Zhang Di , Sheng Chen Xing
Published: March 2014

For evaluate the risk of civil marine nuclear power plant, through the searching related standards for ship, external environmental parameters that the nuclear ship should be suited was found. Based on the characteristics of power plant of civil nuclear-powered ship, the hierarchy system of primary loop system was established and corresponding indicator marking criteria were formulated for the risk assessment. The result shows that the Reactor Safety Injection System (RIS), the Reactor Boron and the Water Supply System (REA), the Control Rods and the Hull of Fuel Canning are the key risk factors in the primary loop system. Finally, the comprehensive evaluation was carried out for collision, stranding and swing of multi-degree of freedom, and put forward relative countermeasures to cope with the possible risks based on the comprehensive evaluation and combined with the literatures.
The Combined Solar with a Dual Heat Source Heat Pump Applied in a Greenhouse Heating System - An Operation Optimization of Water Source Heat Pump
Authors: Sun Xian Peng , Zou Zhi Rong , Zhang Yue
Published: March 2014

Based on the finite-time thermodynamic theory, an operation optimization, of water source heat pump in the combined solar with a dual heat source heat pump which is applied in a greenhouse heating system, is made. According to the ε-NTU method and entropy theory, heat exchange and balance equations are obtained. The function relationship between COP and the indoor temperature Tn, the ambient temperature Ta, low temperature heat source inlet temperature Tie and high temperature heat source inlet temperature Tic is also obtained. By means of programming, the impact of parameters on the COP and the way of regulating this water source heat pump system are presented in this article. The results show that: when a separate water source heat pump is running, by adjusting the hot water temperature and the match status of each indoor heating system, the energy-saving operation can be realized.
Optimization of Pyrolysis Technical Parameters for Cotton Stalk Based on Response Surface Methodology
Authors: Yang Ying , Zheng Wen Xuan
Published: March 2014

Biomass pyrolysis is a good high-value process of biomass conversion. Study on the pyrolysis products of crushed cotton stalks pyrolysis experiments in the self-made airtight equipment. The effects of three factors (pyrolysis temperature,pyrolysis heating rate and pyrolysis holding time) were investigated by using the mass of the solid products yield as the indexes .Box-Benhnken design ( BBD ) and response surface methodology ( RSM) were adopted to obtain the optimum parameters on the basis of results of single-factor experiments.The results show that: when pyrolysis temperature is 500°C.the heating rate is 9°C/min and holding time is 1h,solid products yield 33.4123%, liquid products yield 36.5699%, and gaseous products yield 30.0178%.
Study on Combustion and Emission Characteristics of Acidic Oil Biodiesel
Authors: Wu Jian , Hua Yang , Wang Zhan Cheng , Zhu Li Li , Wang Hong Ming
Published: March 2014

In order to develop a new fuel alternative for the diesel engine, experiment of combustion and emission characteristics was carried on a high pressure common rail diesel engine fueled with diesel and acidic oil biodiesel blends, then the results were compared and analyzed. The results indicate that after adding acidic oil biodiesel, the ignition delay is prolonged, combustion pressure, maximum rate of pressure rise and maximum combustion temperature all increase. The maximum combustion heat release rate of blended fuel is higher than diesel at low and middle loads, and lower at high load condition. Compared with diesel, HC emissions of blends decrease dramatically with the increases of blending ratio. NOX emissions of blends are slightly higher than diesel. CO emissions of blends are almost the same as that of diesel. According to the results, acidic oil biodiesel has wide application prospects as an alternative fuel.
A New Progressive Curvilinear Strain Energy-Based Crack Growth Modeling Algorithm Using Multicomplex Variable Finite Elements
Authors: Millwater Harry , Wagner David
Published: March 2014

Arbitrary, non-planar progressive fracture analysis is of critical importance to the integrity of structures. While significant progress has been made in the last 25 years, there are still technical issues regarding computational expense, robustness, and accuracy. Based upon the recent significant enhancements available through the use of multicomplex finite element methods, a new high-order progressive strain energy based progressive crack growth algorithm is proposed.
High Temperature Multiaxial Creep-Fatigue Life Prediction for YH61 Nickel-Base Single Crystal Superalloy
Authors: Wang Wen Zhu , Sakane Masao , Itoh Takamoto , Yoshinari Akira , Isobe Nobuhiro , Matsuda Noriaki
Published: March 2014

This paper discusses an evaluation method of creep-fatigue lives of YH61 single crystal superalloy under multiaxial loading at high temperature. Three types of creep-fatigue tests were performed using three types of the single crystalsuperalloy specimens at 1173K. They were push-pull tests using solid bar specimens, tension-torsion tests using hollow cylinder specimens and biaxial tension-compression tests using cruciform specimens. Anisotropic strain and Mises stress in combination with frequency modified fatigue equation were applied for evaluating the creep-fatigue lives in the three types of tests. The former parameter gave a relatively large scatter but the latter parameter a small scatter in the correlation.
Anisotropic Life Prediction for Single Crystal Nickel-Base Flat Plate with a Hole
Authors: Dong Cheng Li , Yu Hui Chen , Li Ying
Published: March 2014

The material properties of single crystal (SC) superalloys are orientation-dependent. To fully exploit the material capacity, the life modeling needs to consider the anisotropy. In the present study the life modeling of SC nickel-base superalloys is considered by employing the modified Mücker's anisotropic theory in which a Hill type function is utilized for describing the anisotropic failure. Strain-controlled low cycle fatigue (LCF) experiments of SC nickel-base superalloys at different crystallographic orientations (i.e. [00, [01 and [11) under high temperatures (i.e. 760°C) are carried out to verify the modeling availability for the modified Mücker's anisotropic theory. Further, based on the stress-strain field obtained by the anisotropic elastoplastic constitutive model coupled with the finite element method (FEM), the modified Mücker's anisotropic theory is employed to predict the fatigue life for SC flat plate with a hole.
A Brief History of Structural Fatigue Testing at Fishermans Bend Australia
Authors: Molent Lorrie
Published: March 2014

This paper presents a brief history of fatigue research at the Fishermans Bend Australia Defence Science and Technology Organisation (DSTO) facility from the early days in the 1940s when Mr. H.A. Wills, Head of the then Structures Division, foresaw with remarkable insight the emerging danger of fatigue in aircraft structures. He presented a historic paper at the Second International Aeronautical Conference in 1949 and instituted a comprehensive programme of research on the fatigue of materials and structures which proved to be invaluable within the next decade as fatigue failures began to plague first civil and then military aircraft fleets worldwide.
DSTO is still amongst the world leaders on the fatigue of aircraft structures, as many of these research programmes have won international recognition and as fatigue investigations expeditiously undertaken for the RAAF (and at times civil regulators) have supplied valuable information to the aircraft manufacturers, operators and researchers.
QinetiQ Aircraft Structural Integrity Experience and Lessons Learnt
Authors: Houston Michael , Watters Kevin , Moews Juergen , Stewart Ross
Published: March 2014

QinetiQ has been the primary engineering support contractor to the RAAF airworthiness section (ASI-DGTA) since 1996. Over that 16 year time period many airworthiness investigations and assessments of structural integrity have been performed on a wide variety of RAAF aircraft types and Army rotary wing aircraft. A complete capability has been developed to manage structural fatigue in accordance with airworthiness standards, and indeed to transition the management of an aircraft from a design standard to a preferred RAAF management standard in response to capability requirements. Many important lessons have been learnt and have reinforced the capability. This paper describes some of the major programs that QinetiQ has undertaken for the RAAF, and the lessons learnt from them.
Cost Effective Safety from Full System Teardowns
Authors: Boykett Robert
Published: March 2014

This paper describes techniques for affordable teardowns on aircraft to extract condition data for assessment of system integrity durability and damage tolerance. Studies of fleet accidents show a significant proportion are due to failures in systems other than structures and engines but knowledge of their degradation with usage and age are less well understood. Forensic results from a full teardown provide robust data that supplement design and service data to support safety assessments.
Fleet retirement is a golden opportunity to carry out a full system teardown if it is cost-effective. This permits a condition assessment of all critical systems after decades of Australianspecific configuration, roles and environment. Rapid dismantling techniques that do not destroy key information are being refined. Performance measurements are being compared with original design specifications and forensic data can be compared with non-destructive inspection data.
Development of a Probabilistic Model for the Prediction of Fatigue Life in the Very High Cycle Fatigue (VHCF) Range Based on Inclusion Population
Authors: Kolyshkin Anton , Grigorescu Andrei , Kaufmann Edgar , Zimmermann Martina , Christ Hans-Jürgen
Published: March 2014

The aim of the present work is to develop a statistical approach for the correlation between the quality of metallic materials with respect to the size and arrangement of inclusions and fatigue life in the VHCF regime by using the example of an austenitic stainless steel AISI 304. For this purpose, the size and location of about 60000 inclusions on cross sections of AISI 304 sheet in both longitudinal and transversal directions were measured and subsequently modeled using conventional statistical functions. In this way a statistical model of inclusion population in AISI 304 was created. The model forms a database for the subsequent statistical prediction of inclusion distribution in fatigue specimens and the corresponding fatigue lives. By applying the extreme value theory the biggest measured inclusions were used in order to predict the maximum inclusion size in the highest stressed volume of fatigue specimens and the results were compared with the failure-relevant inclusions. The location of the crack initiating inclusions was defined based on the modeled inclusion population and the stress distribution in the fatigue specimen, using the probabilistic Monte Carlo framework. Reasonable agreement was obtained between modeling and experimental results.
Influence of Short Thermal Cracks on the Material Behaviour of a Railway Wheel Subjected to Repeated Rolling
Authors: Caprioli Sara , Ekberg Anders
Published: March 2014

An analysis of whether and how the occurrence of shallow (radial) thermal cracks promotes additional plastic deformation of a mechanically loaded wheel tread is carried out. The study employs numerical simulations of a 2D slice of an elastoplastic railway wheel tread containing thermal (radial) cracks. The cracked wheel material is subjected to repeated passes of a frictional rolling contact load. The effect of the existing thermal cracks on bulk deformation and subsequent rolling contact promoted growth is quantified. Results indicate that thermal cracks of a depth of 0.1 mm have a negligible effect, whereas 1.0 mm cracks significantly decrease the bulk resistance of the wheel material. Further, it is shown how the magnitude of stress, strain and deformation depends on the direction of applied traction.
Fatigue Life Improvement of Laser Clad 7075 Aluminium Alloy by Deep Surface Rolling Technique
Authors: Liu Qian Chu , Zhuang Wyman , Sharp Peter Khan
Published: March 2014

The Deep Surface Rolling (DSR) technology can substantially increase the fatigue life of metallic materials due to the introduction of deep compressive residual stresses in the material surface. These beneficial compressive residual stresses can be achieved up to a depth of 1 mm. The DSR technology also produces a good surface finish unlike bead peening technology.
In this study, the main objectives were: (1) to study the feasibility of DSR for fatigue life improvement of high strength aluminium alloy (7075-T651) repaired with laser cladding technology, and (2) to investigate the effect of thermal stressing on the fatigue life improvement of DSR. Previously published results have shown that post-heat treatment of laser clad high strength Al alloy coupons improved their fatigue life. The experimental results in this paper show that the fatigue life was substantially increased using the DSR technique on laser clad 7075-T6 aluminium alloy compared to laser cladding alone and laser cladding followed by post heat treatment.
Material Modelling and Lifetime Prediction of Ni-Base Gas Turbine Blades under TMF Conditions
Authors: Gruetzner Stefan , Fedelich Bernard , Rehmer Birgit , Buchholz Bjoern
Published: March 2014

Under cyclic thermomechanical loading conditions, various damage mechanisms such as strain accumulation, creep cavitation, ageing, fatigue surface cracking etc. may take place in the material of a gas turbine blade. Depending on the loading conditions, all these effects can contribute to reduce the lifetime of the component.
Subject of the present work is the development of a material model to describe the mechanical effects mentioned above, as well as the development of a lifetime model able to discriminate the different damage mechanisms.
Evaluation of Conventional Al 2024 Fatigue Limit in Fatigue Test Using Thermographic Measurement: Effect of Frequency
Authors: Seitl Stanislav , Klusák Jan , Fernández Pelayo , Canteli Alfonso
Published: March 2014

The reliability of the conventional fatigue limit estimation of aluminum alloy Al 2024 provided by thermographic measurements according to the Risitano method is investigated in order to check their validity for practical applications. With this aim, an experimental fatigue program on Al 2024 specimens under load control using a stress ratio R = 0.1 is performed at three different frequencies. The fatigue limit methodologies is first determined according to the methodologies proposed by Risitano et al. and Canteli et al., and then compared with that resulting from the conventional Wöhler curve.
Visualization of Multiaxial Stress/Strain State and Evaluation of Failure Life by Developed Analyzing Program under Non-Proportional Loading
Authors: Liu Shu Li , Itoh Takamoto , Fujii Noriyuki
Published: March 2014

This study presents definitions of principal stress/strain range and mean stress/strain introduced by utilizing Itoh-Sakane criterion for multiaxial loading including non-proportional loading, and shows the method of calculating the non-proportional factor which expresses the severity of non-proportional loading under the multiaxial 3D loading. This paper also shows a method of visually presenting the stress/strain, the non-proportionality of loading and the damage evaluation.
Partition of Cyclic Plasticity in an Austenitic-Ferritic Duplex Stainless Steel and its Significance for Fatigue Crack Initiation under High and Very High Cycle Fatigue Loading Conditions
Authors: Dönges Benjamin , Söker Marcus , Giertler Alexander , Krupp Ulrich , Fritzen Claus Peter , Christ Hans-Jürgen
Published: March 2014

The present study documents that at loading amplitudes close to the fatigue limit, cyclic irreversible plastic deformation in form of slip band generation in the austenitic-ferritic duplex stainless steel X2CrNiMoN22-5-3 (318 LN) mainly takes place in few austenite grains without any microcrack initiation in these grains. This was shown by means of focused ion beam (FIB) cutting in combination with high resolution scanning electron microscopy (SEM) at pronounced extrusion-intrusion-pairs in several austenite grains. Investigations by means of confocal laser scanning microscopy (CLSM) revealed that the slip band density in these grains increases with the number of loading cycles and remains constant in the very high cycle fatigue (VHCF) regime. Under such loading conditions, fatigue cracks frequently initiate in the ferrite phase due to anisotropy stresses which are strongly superimposed by stress intensifications at the tip of austenite slip bands. TEM investigations revealed that austenite slip bands, which are piling up against phase boundaries, cause localized dislocation generation and motion in neighboring ferrite grains. The cyclic irreversible motion of these dislocations on several parallel slip planes is correlated with the stage of fatigue crack initiation. A crystal plasticity model based on a finite element program, which considers anisotropic elasticity, allows for the determination of crack initiation sites in real microstructures according to the above mentioned mechanisms. Crystallographic orientations, measured by means of the electron back scatter diffraction (EBSD) technique, serve as input parameters for the calculations regarding microcrack initiation as well as for the analysis of the subsequent short fatigue crack propagation, which is strongly affected by microstructural barriers such as grain and phase boundaries.
Influence of Frequency and Testing Technique on the Fatigue Behaviour of Quenched and Tempered Steel in the VHCF-Regime
Authors: Schneider Norbert , Pyttel Brita , Berger Christina , Oechsner Matthias
Published: March 2014

Today in many cases ultrasonic testing machines with a frequency of f ≈ 20 kHz are used for investigations of the fatigue behaviour up to the very high cycle regime (VHCF-regime). A question that arises is if the results of these high frequency fatigue tests are comparable to conventional fatigue tests. This paper compares the fatigue behaviour of a quenched and tempered steel 50CrMo4 in two different tempered conditions investigated at low frequencies (f ≤ 400 Hz) on a servohydraulic testing machine and at a high frequency (f ≈ 20 kHz) on an ultrasonic fatigue testing machine. Effects which can occur because of the different testing techniques and testing frequencies are investigated. A concept is derived to describe the frequency effect caused by the strain rate. The estimations are compared with results of the fatigue tests.
Influence of Process-Related Defects on the Fatigue Behaviour of Welded Aluminium Joints at Very High Cycles
Authors: Cremer Martin , Kolyshkin Anton , Zimmermann Martina , Christ Hans Jürgen
Published: March 2014

The influence of geometrical notch and weld defects (pores and incomplete fusions) on the fatigue behaviour at very high numbers of loading cycles is shown for welded samples made of the base material EN AW-5083 and EN AW-6082 and the filler material S Al 5183. High frequency fatigue tests with specimens highest stressed cross-sections representing different welding zones show no endurance limit up to 2·109 load cycles. The weakest link of the weld seams are the geometrical notch and (if present) pores and incomplete fusions in the seam interior and at the surface. Considering weld defects in the filler material as fatigue crack initiating notches, a threshold value for the cyclic stress intensity factor (ΔKmin) of 0.9 MPam was found. Using ΔKmin the fatigue life of the samples is discussed on the basis of stress amplitude, the projected area of the defect and its position. X-ray examinations revealed a good correlation between the failure-relevant defect areas and the overall fatigue life of welded samples.
Effect of Fine-Grained Microstructure Induced by Induction-Heating Fine Particle Peening Treatment on Fatigue Properties of Structural Steel (0.45%C)
Authors: Murai Kazue , Toyama Ryota , Komotori Jun , Fukazawa Kengo , Misaka Yoshitaka , Kawasaki Kazuhiro
Published: March 2014

To improve the fatigue properties of structural steel, a novel surface modification process which combines high-frequency induction heating (IH) with fine particle peening (FPP) was developed. IH-FPP treatment was performed on the surface of structural steel specimens (0.45%C) at temperatures from 600 to 750 °C, with peening times of 60 and 120 s. To determine the characteristics of the treated surfaces, the microstructure was observed using an optical microscope and a scanning electron microscope. Vickers hardness and residual stress distributions were also measured. The characteristics of fine-grained microstructures were examined by electron backscatter diffraction. Furthermore, in order to investigate the effect of the grain refinement achieved by IH-FPP treatment, rotational bending fatigue tests were performed on treated specimens. Results showed that IH-FPP treatment created fine-grained microstructures beneath the surfaces of steel samples. The average ferrite grain size was 4.06 μm for a treatment temperature of 700 °C, and finally 0.76 μm for 600 °C . This was due to dynamic recrystallization in the processed region. IH-FPP treated specimens exhibited a higher fatigue strength than untreated specimens. As almost no compressive residual stress was measured in the treated or untreated specimens, the increase in fatigue strength resulting from IH-FPP treatment was due solely to grain refinement.