bluuebunny/crossref_metadata_2025 huggingface dataset:
Discussion on the Technology Application of OFDM in the Ad-Hoc Network of Unmanned Aerial Vehicle (UAV)
Authors: Yuan Zheng , Yang Shang Dong , Liu Hong Wei
Published: December 2014

The coordination model of UAV network is attracting widespread attention. Considering from the flight characteristics of UAV, the Ad Hoc network should be adopted. This paper analyzes the characteristics of Ad Hoc network, and focuses on the further discussion on the physical layer technology OFDM to conclude that the application of OFDM technology in the UAV network communication can improve the data transmission capability.
A Novel Anti-Collision Algorithm of Tags in RFID System
Authors: Zong Xiao Ping , Lu Rui Kuan , Wang Pei Guang , Zhang Ting , Liu Sen
Published: December 2014

Anti-collision algorithm of label is a key technique to enhance identifying efficiency in the RFID system. This paper make a new conception of couple of single-bit collision that based on the elementary query tree algorithm and two improved algorithm analyzed in detail. Meliorating the both back query tree algorithm and dynamic back query tree algorithm by single-bit anti-collision algorithm could achieve the function that discern double labels at the same time by inquiry once. Simulation results show that the single-bit anti-collision could reduce times and time of total inquiries, particularly, dominant improvement of deterministic algorithm by this algorithm when the amount of labels above and beyond half capacity permitted by collision bits.
Design Method of an Intermediate Transcoding Structure Based on XML
Authors: Pu Ai Min
Published: December 2014

With the development of wireless communication and networks technologies, the WAP is widely used. For the WAP, HTML needs to be transcoded into WML pages, so as to implement information browse of wireless terminals. This paper designs an intermediate transcoding model based on XML, which can solve the problem of transcoding from HTML pages to WML pages through XML intermediate bridge. This paper implements the design of the model, and then the experiment of pages transcoding is tested based on text file examples. The experiment results show the transcoding model has more accuracy and higher efficiency than other methods.
Modulation Type Recognition of OFDM Signals Based on EMD
Authors: Gong An Min , Wang Bing He , Qu Yi , Zheng Yao Rui
Published: December 2014

This paper used the Empirical Mode Decomposition (EMD) ,solving the problem of the modulation type recognition of Orthogonal Frequency Division Multiplexing (OFDM) on blind signal Processing of communication .This method uses the characteristics of the OFDM' envelope nearly Gaussian .Using the EMD decomposition algorithm of signal decomposition, extract the intrinsic mode function (IMF) after signal decomposition and computes the correlation co-efficient of IMF and the original signal as the recognition feature .So as to achieve that identification the OFDM signals and single carrier linearly digitally modulated (SCLD) signals (MFSK(2FSK, 4FSK), MPSK(BPSK, QPSK)) without prior knowledge. Experiments show that this method has a good performance with less computation, and this method also has well Real-time and robustness compare with the methods of the wavelet transform and the higher order cumulants.
High Performance Start Node of Edge Ordering for Infrastructure Networks
Authors: Xie Bin , Liu Xuan , Mo Yu Chang
Published: December 2014

During the reliability analysis of infrastructure networks based on Binary Decision Diagram (BDD), we studied the high performance start node for edge ordering. We use node’s betweenness to divide the network into several partitions, and show the relation between high performance start nodes and network partitions. We summarized the distribution patterns of the high performance start nodes. The experiment results on selected aviation network shows that we can select high performance ordering start nodes for large-scale networks by using these patterns and network partitions. Thus, we can enhance the performance of network reliability analysis algorithm.
The Applications of Information Visualization in Power Systems
Authors: Wang Xiang Li , Lu Ming Xing , Cai Dong Dong , Nian Yu Gui
Published: December 2014

Power system visualization technology is essential in improving the power system automation and human-computer interaction environment. The power of information visualization technology can display a lot of information in a computer-generated image, and help system personnel to process and analysis of numerous grid data more efficiently. It provides a more intuitive operating platform for system operators.
The Application of Communication Network in Distribution Automation
Authors: Ding Ya Wei , Cai Dong Dong , Nian Yu Gui , Wang Yong Chao
Published: December 2014

With the rapid development of China's economy and society, the power supply quality and reliability have become increasingly demanding for power user. Distribution automation becomes a power system to be implemented one of the goals based on the gradual promotion of information technology in promoting economic construction. This paper studies the distribution network communication method to determine the communication system hierarchy. Distribution communications network will cover the entire distribution automation master, terminals and related services, enabling the communication network can effectively meet the distribution automation system needs.
The Application of Distribution GIS in Regional Distribution Network
Authors: Yang Zhao , Tang Yang , Zhang Yu Qiong , Wang Chen Chen
Published: December 2014

It used GIS approach to manage the distribution network, and it has a comprehensive analysis in the distribution network management system. It provide the distribution of professional management decision analysis that can greatly facilitate the management of the distribution network of various types of data, while the planning and management process more direct and interactive. This paper describes the application of GIS in Distribution Network.
Influence of Guide Vane Wrap Angle Key Design Parameters on Hydraulic Performance of Nuclear Reactor Coolant Pump
Authors: Jin Wei Nan , Xie Rong , Hao Mu Ting , Wang Xiao Fang
Published: December 2014

To study the effects of guide vane with different vane wrap angles and relative positions of outlet edge on hydraulic performance of nuclear reactor coolant pump, three-dimensional steady numerical simulations were performed by using CFD commercial software Numeca. The results show that the vane wrap angle changes the head and power characteristics by changing the relative velocity angle in vane outlet. The inner flow field changes while the wrap angle changes. With the wrap angle increases, the shock loss in volute is reducing, but the friction loss in vane passages is getting large. So there exists an optimum wrap angle and relative positions of outlet edge that corresponds to the highest efficiency of a pump. Numerical simulation is performed with the two key design parameters optimized through surrogate model, the internal flow field is improved and then the hydraulic efficiency is improved.
The Application of Gaussian Mixture Modeling in Traffic Flow Videos
Authors: Lv Wen Yan , Yang Hong Ye , Wang Rui , Li Jin Ying
Published: December 2014

Traffic flow video processing is an important direction of the development of intelligent transportation, Gaussian mixture background modeling is one of commonly algorithms to build background modeling that is widely used in image processing field. In order to analysis the algorithm comprehensively ,in this paper, it calculus on formula as well as tests and compares some traffic flow videos, the solution based on the K-means, EM parameters model are presented, it gets the mathematical meaning and evolution process of the algorithm clearly by calculating formulas to provide theoretical guidance for practical application; the traffic flow videos processing can get the treatment ability of this algorithm according to the different situation of videos, analyze the mixed Gauss background modeling for time migration, the light changing, moving object shadow processing ability. In this paper, the algorithm of mixed Gauss background modeling is analyzed from two aspects of theory and application.
The Application of Improved PSO Algorithm in PMMW Image OSTU Threshold Segmentation
Authors: Chen Peng , Zou Tao , Chen Jia Yong , Gao Zhi , Xiong Jing
Published: December 2014

The study of passive millimeter-wave (PMMW) image with low resolution and high noise is a research hotspot recently. Therefore, 2D OSTU threshold segmentation method is introduced into PMMW image processing. However, traditional 2D OSTU method has gorgeous calculation and low operation efficiency. As a result, Multi-Period Particle Swarm Optimization (MP-PSO) algorithm is proposed to achieve the goal of fast segmentation. Experiments show that MP-PSO can not only avoid premature convergence of PSO and improve the accuracy of the search, but also be more accurate and efficient. It is convenient for PMMW image real-time processing.
Numerical Investigation on the Flow in Tip Clearance of the Last Three Stages of Industrial Steam Turbine
Authors: Sha Zhao Jun , Xie Rong , Wang Xiao Fang , Ding Xu Dong , Sui Yong Feng
Published: December 2014

Numerical investigation was conducted on the full-three-dimensional flow in the last three stages of steam turbine using by the commercial computational flow dynamics software CFX. And the equilibrium condensation model was adopted to describe the wet steam two phase flows. This article analyzes the internal flow of the turbine with tip clearance and the structure of the leakage flow.
Synthesis and Photoelectric Properties of Donor-Acceptor-Donor Molecule Containing Perylene Diimide
Authors: Jiao Chun Ming , Yi Si Li , Zhou Gang Ming , Xu Qing
Published: December 2014

In this paper, a novel perylene diimide derivative 1, 7-bis (N, N-bis (4-phenyl) aniline) perylene diimide (PDI-TPA) was synthesized and characterized by IR spectroscopy, 1H NMR and elemental analysis. Besides, solubility and photoelectric properties of PDI-TPA were studied. Results were shown that PDI-TPA exhibited an excellent solubility in common solvents. The absorption bands spanned a wide range of the visible spectra and optical band gap was 1.68 eV. In addition, PDI-TAP exhibited an ambipolar behavior, the highest occupied molecular orbital (HOMO) energy level and the lowest unoccupied molecular orbital (LUMO) energy level were-5.64 eV and-3.94 eV, respectively.
Dynamic Analysis and Optimization of Pivot Points of Telescopic Jib Based on Genetic Algorithm
Authors: Liu Tao , Wang Wei Hui , Yuan Ren Wu , Lu Fei
Published: December 2014

Using ADAMS software to create a virtual prototype model of luffing mechanism of QY20A crane truck. The entire work process of telescopic arm is analyzed, and the result shows that luffing cylinder lifting force is maximum at the beginning moment. The luffing cylinder force is calculated in different conditions based on the analysis and select the maximum force condition as optimized conditions, make the mathematical model of optimization and optimized using genetic algorithm, which played a guiding role for the of telescopic boom design.
Finite Element Analysis of Z-Shaped Pipe in the Directly Buried Heat-Supply Pipeline with Large Diameter
Authors: Li Ming Qiang , Wang Fei , Wang Guo Wei , Lei Yong Gang
Published: December 2014

In order to improve Z-shaped pipe in the directly buried heat-supply pipeline with large diameter stress calculations, guiding the engineering design when the short arm length is less than two times the elastic arms length. The author used ANSYS software to numerical simulation analysis on Z-shaped pipe in the directly buried heat-supply pipeline of DN800, DN1000, DN1200, when the long arm length of 50 m, 100 m, 150 m, and the short arm length from two times to one times of the elastic arm length. Applying boundary conditions in different models with the short arm length shortens the process to Z-shaped pipe of the elbow stress. For Z-shaped pipe in the directly buried heat-supply pipeline the short arm from two times to one times of the elastic arm length, the elbow’s stress value is the minimum when the short arm length is 1.2 times of the elastic arm length. This article breaks the specification limits on the short arm length, improving the flexibility of directly buried heat-supply pipeline with large diameter, reducing the difficulty of construction, and it’s important for guiding the actual project.
Influencing of Combustion Ecology of Diesel Engines by their Intake Resistance
Authors: Záležák Zoltán , Bernát Rastislav , Kecskés Norbert
Published: December 2014

As it is generally known, diesel engines operate with air excess, i.e. lean mixtures. Intake resistances in intake manifolds of diesel engines negatively influence their ecological parameters. Based on these facts, we may conclude that less air in the intake manifold causes increased production of exhaust fumes and fuel consumption. One of the reasons of increased intake resistance is a blocked air filter. In the experiment, we have simulated the increased intake resistance and wished to point out possible consequences of pressure drop at the end of the compression stroke. The choking effect was realized by means of a throttle and scale, which was mounted on the air filter position. By using the dynamic method and obtained results, we found that choking at the rotation angle of 90° and 45° caused the difference of 0.16 MPa of the measured quantity during the maximum revs set on 2000 min-1. The difference in pressure at the end of the compression stroke with the rotation angle of 30° and 90° was by 0.86 MPa higher. Pressure drop in manifold showed the value 0.15 MPa. Manufacturers recommend regular replacement of air cleaners of combustion engines in service intervals; however, we must also keep in mind the environment in which the engine operates. In excessively dusty and otherwise polluted areas, it is necessary to replace cleaners a bit earlier.
Nitrogen Effect on Mechanical and Tribological Properties of STN 41 5230 Steel Surface Layer
Authors: Kováč Ivan , Mikuš Rastislav , Žarnovský Jozef , Ružbarský Juraj
Published: December 2014

The subject-matter of this article is using diffusion processes to obtain chemically stable compounds with a low reactivity and higher mechanical properties in material surface layer. These processes were implemented by remelting the surface of a given material in arc process using a TIG welding method. Nitrogen was used as an alloying element in experiments. The experiment assumed that the dissociation and ionization of gases, enabling the ionization of diffusion processes in the surface layer of remelted steel, will be achieved by means of electric arc. Conditions for the formation of hard and stable structures with required properties should have been created by enriching the surface layer. The STN 41 5230 steel was used in experiments. After remelting, samples were examined on hardness and relative abrasive wear resistance, which are crucial in terms of required properties of given surface layers. In addition to hardness values in the surface layer, also its behaviour inwards the material up to thermally unaffected base material was determined. When remelting in the environment containing nitrogen, the values of examined quantities increased.
Comparison of Spectral Reflectance and Multispectrally Induced Fluorescence to Determine Winter Wheat Nitrogen Deficit
Authors: Galambošová Jana , Macák Miroslav , Živčák Marek , Rataj Vladimír , Slamka Pavol , Olšovská Katarína
Published: December 2014

Technical and technological aspects of variable rate nitrogen fertilization receive much attention nowadays. Current commercial technology is based on the use of spectral reflectance of crop. However, these have some limitations as variety dependence, crop health effect and limited use in more developed growth stages. New parameters overcoming these problems need to be assessed and their potential in precision agriculture should be considered. Multispectrally induced fluorescence is a progressive method. In addition to chlorophyll content, it allows to determine phenolic compounds, which is a product of metabolism of the plant under nitrogen deficit and is considered as the most exact indicator of nitrogen deficit. Comparing the spectral reflectance indices (normalized difference vegetation index – NDVI and normalized difference red edge index – NDRE) and multispectral fluorescence index (nitrogen balance index – NBI), these performed similarly in terms of determining the leaves biomass and nitrogen content in %, NDRE and NBI reflected significantly also aboveground N; however, only the correlation of NDVI reflected with N uptake and with leaf area was highly significant.
Hardpan Location and Crop Yield: From Information to Precision Tillage Map
Authors: Kollárová Katarína , Žitňák Miroslav , Korenko Maroš
Published: December 2014

This paper explores the incidence of hardpans in a field of 14.27 ha. Emphasis is placed on winter wheat yield and its comparison with hardpan location. The objective of this study was to determine prescriptions of different tillage depths for a precision tillage map. In order to meet the above objectives, laboratory and field experiments were conducted based on the experiment design with 60 monitoring points. The results of experiments confirmed the within-field spatial variability of hardpans and crop yield and revealed areas where yield is influenced by detrimental compaction.
Hardness and Microstructure Analysis of Deposit Material Based on Fe-Cr-Ni
Authors: Mikuš Rastislav , Szabó Viliam , Drlička Róbert , Bakajová Jana
Published: December 2014

The paper deals with the hardness, chemical composition (using spectrometer) and microstructure (using light microscopy and scanning electron microscopy with EDX spot analysis) of the weld deposit based on Fe-Cr-Ni used for renovation of the functional surface of wheel for mineral wool spinning and with impacts of operational processes onto these characteristics. Deposit samples were analysed after service wear having an abrasive-erosive-thermal character. Analysis results were compared to a deposit sample with no wear. Based on results of weld deposit microstructure analysis, duplex ferrite-austenitic structure with ferrite matrix and austenite precipitation in various morphologies was found in the all cases. No substantial hardness changes caused by operational processes were found by comparing the analyses results. Increased melt temperature was the most important process parameter affecting the chemical and phase composition of the examined material, inducing the precipitation of new phase with a high Cr content.
Possibilities of Using Ecological Fluid in Agriculture
Authors: Kučera Marian , Bujna Marián , Korenková Marcela , Haas Peter
Published: December 2014

This paper deals with the issue of using ecological oils in the sliding pair of hydraulic and transmission systems working in the area of agriculture. The sliding pair included a B 60 bearing and a journal with contact surface made of 14 220 steel. The experimental tests were carried out with two oils: the Fuchs Plantohyd 46 S ecological oil and PP 80 reference oil (producer: Slovnaft) which is a commonly used lubricant in given conditions. The results of the experiments were statistically processed and based on them, friction coefficient and temperature, both depending on the test duration, was evaluated. Consequently, the weight loss and roughness change of both tribological elements were statistically processed.
Passivation of Zinc Coatings by Inhibition Chrome-Based Systems
Authors: Votava Jiří , Kotus Martin , Kumbár Vojtěch
Published: December 2014

The anticorrosion resistance of metal (inorganic) coatings is defined by the system of anode and cathode protection. As zinc coatings do not load the environment in such an extent like organic paint systems, current trend is to maximally prolong the service life of a zinc coating. This paper is focused on analysis of the speed of corrosion degradation of zinc coatings. The individual samples were prepared by the method of hot-dipping and galvanizing. Inhibition systems were applied only to electrolyte-applied zinc coating. There were prepared three different passivating methods: (1) slim-layer passivation with the content of Cr (III), (2) slim-layer passivation with the inhibitor Cr (VI) and (3) thick-layer passivation with Cr (III). The thickness of anticorrosion coatings has been measured by both destructive and non-destructive methods. The weight of the applied anticorrosion substrate was measured in compliance with the ČSN EN ISO 3892 standard. Ductile characteristics were analysed according to the ČSN EN ISO 1519 standard. The total evaluation of anticorrosion resistance was processed according to the ČSN EN ISO 9227 standard (salt-spray test). Based on the results of corrosion tests, the individual coatings can be analysed and their corrosion resistance can be evaluated. The service life of the zinc coating can be prolonged by sealing off the zinc coating by an appropriate inhibitor which supports the self-healing effect of the whole anticorrosion substrate.
Setting Marginal Limits of Stress of Quick-Setting Adhesives Based on Cyanoacrylates
Authors: Müller Miroslav , Mikuš Rastislav
Published: December 2014

The application of quick-setting adhesives based on cyanoacrylates is considerably spread in technical practice. The limit of these adhesives is the 'zero layer' of the adhesive. The advantage is in the speed of hardening process. A fast creation of bond, minimalizing of fixation means, and the possibility of fast manipulation with the adhesive bond are connected with that. The goal of the research is to describe the behaviour of quick-setting adhesives based on cyanoacrylates at different speed of deformation of adhesive bonds in the interval from 1 mm.min-1 to 48 mm.min-1. The change of adhesive bond strength, deformation and failure time were evaluated in experiments. A 3D model was set from experiment results by means of the least-square method.
Effects of Initial Material Conditions on the High Temperature Surface Oxidation of Press-Hardening Steels
Authors: Deng Biao , Yi Hong Liang
Published: December 2014

The 22MnB5 steel of Wuhan Iron with three early treatment (pickling, cold-rolling and cold-rolled annealing), then high-temperature oxidation, surface morphology and element of the oxide layer were observed after oxidation testing. The result shows that the oxide layer thickness of cold-rolled annealed sheet is maximal, followed by cold rolled sheet, the pickling sheet is minimum; The surface roughness is associated with degree of oxidation; Si and Cr content increase sharply in oxide layer of 22MnB5 steel after annealing, annealing and cold rolling have little effect of Mn content in the oxide layer.
Thermal and Mechanical Characteristics of a HSLA Steel as Joint Partner for Hot Stamping Tailor Welded Boron Steel
Authors: Tang Bing Tao , Wang Qiao Ling , Zheng Wei , Yuan Zheng Jun
Published: December 2014

In order to further reduce the weight and at the same time guarantee the automobile safety, hot stamping of Tailor-Welded Blanks (TWBs), is developed recently to meet the environmental and safety requirements by supplying car structural body components with functionally optimized and tailored mechanical properties. In the article, an appropriate partner material for the quenchenable boron steel B1500HS based on the phase transformation and deformation behavior under process relevant conditions is determined. Microhardness is measured and metallographic is investigated. It is verified that the B340LA steel is an appropriate joint partner with ideal thermal and mechanical properties.
Localized Austenitizing of the Blank to Make Tailored-Properties by Induction Heating
Authors: Liu Pei Xing , Yi Hong Liang , Xu Ya , Wang Yi Lin , Zhang Yi Sheng
Published: December 2014

In this research, a novel hot stamping process to make tailored-properties is proposed. The local areas of blank are heated by induction heating. In the high strength zones, they are heated to austenitizing temperature, and in the absorption zones without heating. The temperature field of transition zone is determined by the thermal conduction between austenitizing temperature and ambient temperature. This novel process can be used for industrialization without changing mold design and stamping process.
Non-Uniform Contact and Friction Sensitivity on Formability of Boron Steel in Hot Stamping Process
Authors: Liu Yong , Gui Zhong Xiang , Huang Zhi Gao , Wang Yi Lin , Zhang Yi Sheng
Published: December 2014

Hot stamping parts made of boron steel have been widely used in automotive industry. In forming process of a hot-stamped vehicle bumper, non-uniform contact and friction between the boron steel and tools caused the bumper groove sidewalls excessive thinning or crack. Increasing stamping speed could improve the non-uniformity of blank temperature field and reduce the temperature difference. Influence of the stamping speed and the friction on the forming quality were studied by numerical simulation. The results showed that increasing the stamping speed within a certain range or using reasonable lubrication could reduce the thickness reduction of the sidewall. A bumper without cracking was obtained with a high stamping speed of 300 mm/s and a certain lubrication method.
The Development and Application Research of Light Weight Heat Treated C-Grade Bullet Proof Steel
Authors: Ma Ming Tu , Chen Gang , Ma Yu Hao , Li Zhi Gang , Feng Yi
Published: December 2014

The Light weight heat treated C-grade bullet proof steel was developed through composition design and optimization based on multiplex alloying, multiplex micro-alloying design ideas and complex phase structure strengthening theory. The puzzle how to avoid the quenching deformation problem of super high strength thin sheet was solved through heat treatment in die with a suit of cooling system. Such C-grade bullet proof steel plate has fine tempered lath martensite structure and has a higher strength than production which is made by a Inc. in Sweden. The shooting and certification test results show that the shot resistance of C-grade bullet proof steel plate can met the protection demand of the Protection specification for cash carrying vehicles (GA164-2005)standard. Comparison with C-grade bullet proof steel plate made by a Inc. in Sweden, the developed C-grade bullet proof steel plate can degrease 5 to 10% weight under the same shot resistance condition. It will be in favour of lightweight for cash truck and anti-hijacking vehicle and energy conservation and emission reduction.
Hot Stamping Technology Applied on Vehicles on EuroCarBody
Authors: Zhou Jia , Ma Ming Tu
Published: December 2014

EuroCarBody, offer the most important forum for defining and discussing the state of the art in modern series car body engineering. The present paper concerns the materials of press hardened steels and its’ manufacturing technology (Hot stamping) applied on vehicle on EuroCarBody from 2009 to 2013 through presentations and benchmark datas. The using percentage of press hardening steels (PHS) on body in white (BIW) are summarized and analyzied. It can be noted that the number and weight of BIW parts using of press hardening steels are increasing from 2009 to 2013, some kind of vehicle, such as Audi A3, the using percentage of PHS reaches 21.6%. The press hardening steels have started used on commercial vehicle from EuroCarBody 2013. More and more new technologies applied on hot stamping processing, such as Joule heating for hot stamping, Hot-form-process partial tempering, Tailor Rolled Blank (TRB) technolgy, etc. With the developing of the automotive industry, more and more hot forming parts will be applied on vehicles in the future.
Ultra-High Strength Steel Hot Stamping Technology and Devices
Authors: Shan Zhong De , Yan Qin Tai , Jiang Chao , Rong Wen Juan
Published: December 2014

Ultra High Strength Steel (UHSS) hot stamping technology is a special process which can enhance the steel tensile strength to 1500MPa. Appling this technology in producing vehicle structure parts can make car lighter and safer. In China there are more and more automobile enterprises adopt this technology. To master and extend the skill, China Academy of Machinery Science & Technology (CAM) have done systematic research, such as the strengthen mechanism of the steel, hot stamping key devices designing, forming and quenching integrated mould designing, stamping process parameters optimization, etc.. By now, CAM has mastered the mass production technology of vehicle parts, which can guarantee its shape and tensile strength, and produced such typical parts as door-beam, B pillar, etc.. The paper is an introduction of the research work and achievement about UHSS hot stamping developed by CAM.
Hot Stamping Simulation with PAM-STAMP of the B-Pillar of a Well-Known SUV
Authors: Wang Wei , Ma Jie Li
Published: December 2014

Hot stamping is today the most efficient method to lighten automotive parts by keeping or even increasing vehicle security. The B-pillar of this report is from a well-known SUV’s style 2013 from a big JV OEM in Shanghai. 3 steps job were completed: die designing, blank generation and optimization, hot stamping simulation. Customer’s feedback showed a good correlation between FE analysis and trial out results.
Study on Three Dimensional Direct Coupling Simulation of Induction Heating for Hot Stamping
Authors: Li Yong , Liang Xiong , Wang Zhao Dong , Li Jia Dong , Fu Tian Liang
Published: December 2014

As to the conventional hot stamping furnance’s shortcomings of long heating time, easy oxidized, high energy consumption, the application of induction heating for hot stamping were studied. By using COMSOL Multiphysics software, we calculated the electromagnetic induction field and temperature field by use of the direct coupling (Direct Coupling Method) in the heating process of hot forming sheet and studied the influence of inductor device parameters (such as induction length, distance between inductor and sheet etc.) and various process parameters (such as the power supply frequency, current density, sheet thickness etc.) on heating rate and temperature distribution. That will have a good guidance on the application of induction heating to hot stamping field.
The Process Optimization to Prevent the Local Wrinkles of Hot Stamping Parts and the Design of Tools
Authors: Sun Shao Li , Wang Zi Jian , Yao Xiao Chun , Wang Yi Lin , Zhang Yi Sheng
Published: December 2014

During the process of hot stamping, due to the deformations of sheet metals are mainly bending and shallow drawing, as well as to prevent the temperature strikingly drop caused by the local contact of sheet metal and die, the hot stamping tool usually does not set up blank-holder. And this leads to the occurrence of local wrinkles in some types of hot stamping parts, which affect the quality of the parts. Through the hot stamping tool design and process test of a car ́s B pillar, it discovered that the local wrinkle in the part ́s big end is more severe. As a result the program was modified by taking advantage of the forming principle of the counter punch to improve the design of upper tool (die), which eliminated the local wrinkle in the big end and improved the contact cooling efficiency, consequently ensured the hot forming parts ́ quality and reduced the production rhythm.
Optimized Design and Numerical Simulation of B-Pillar Reinforcement Panel by Hot Stamping Steel
Authors: Yang Bing , Zhang Ding , Chang Zun Hui , Ge Rui , Wang Zi Jian , Zhang Yi Sheng
Published: December 2014

In a certain vehicle of Dongfeng Passenger Vehicle Company (DFPV), a new design of integrated hot stamping B-pillar reinforcement panel is introduced to replace the original design of two cold stamping parts connecting by spot-weld. A further light-weight design by thickness thinning is also attempted. All the schemes are validated by hot stamping process simulation and vehicle side impact simulation. The results show that by using hot-stamping steel of the same thickness as the original design, the performance of anti-vehicle side impact is improved; and an equivalent anti-side impact performance can be achieved by appropriate thickness reduction, while the weight of the part is lightened.
Prediction of Microstructure and Mechanical Properties in Hot Stamping
Authors: Wang Chao , Zhu Bin , Wang Yi Lin , Zhang Yi Sheng
Published: December 2014

Hot stamping process has been increasingly used in producing structural components of automobile to improve crash worthiness and fuel efficiency. Hot stamping process can produce ultimate tensile strength parts as high as 1500MPa. The high strength of hot –stamped components is attributed to the martensitic phase transformation which is transformed from austenite at elevated temperature. An improved model is developed based on Li’s phase transformation model to predict the austenite decomposition into ferrite, pearlite, bainite and martensite during arbitrary cooling paths for thin sheet boron steel. The simulated volume fractions and hardness profiles shows acceptable agreement to the corresponding experimental observations.
A Force Model for UHSS Hot-Formed Automobile Parts
Authors: Cai Wan Hua , Shan Zhong De , Ye Yong Sheng , Zhuang Bai Liang
Published: December 2014

Combined numerical simulations and experimentally measured data, the relationship between the initial temperature of the workpiece was described, the stamping speed, and the required forming force. Air cooling was included to determine the temperature of the part within the mold, and the required stamping force was optimized by studying the impact of the cooling time on the temperature of the part. The optimized model was verified and validated by comparing simulated data for an anti-collision beam with the experimental results of the hot-forming process. The results showed that the model provides a useful description of the hot-forming process; however, an empirical factor of 0.95 was required to achieve agreement between the simulated and experimentally measured data.
Simulation of Thermal Distortion in Hot Press Forming with Dissimilar Material TWB
Authors: Bok Hyun Ho , Choi Jong Won , Lee Myoung Gyu , Barlat Frédéric , Kim Dong Jin
Published: December 2014

In order to predict the shape change in hot press forming of a TWB made with HPF1470 boron steel and HSLA340 micro-alloyed steel sheets, a coupled thermo-mechanical-metallurgical finite element model was developed to simulate the process. The simulation consisted of air cooling, forming, die-quenching and, finally, by a treatment designed to relax residual stresses. It is shown in this paper that the experimentally observed distortion in the TWB part was reasonably captured by the simulations.
Experimental Platforms and Finite Element Analysis on Hot Stamping Processes
Authors: Hung Tzu Hao , Tsai Heng Kuang , Chen Fuh Kuo , Lee Ping Kun
Published: December 2014

Due to the complexity of hot stamping mechanism, including the coupling of material formability, thermal interaction and metallurgical microstructure, it makes the process design more difficult even with the aid of the finite element analysis. In the present study, the experimental platforms were developed to measure and derive the friction and heat transfer coefficients, respectively. The experiments at various elevated temperatures and contact pressures were conducted and the friction coefficients and heat transfer coefficients were obtained. A finite element model was also established with the experimental data and the material properties of the boron steel calculated from the JMatPro software. The finite element simulations for the hot stamping forming of an automotive door beam, including transportation analysis, hot forming analysis and die quenching analysis were then performed to examine the forming properties of the door beam. The validation of the finite element results by the production part confirms the efficiency and accuracy of the developed experimental platforms and the finite element analysis for the process design of hot stamping.
Microstructure Evolution Behavior of 22MnB5 Pickling Plate during Double Cold Reduction and Rapid Heating Process
Authors: Yao Sheng Jie , Sun Lei , Zhu Hai Hui , Wang Guo Dong
Published: December 2014

The microstructure evolution during rapid induction heating process of 22MnB5 steel after double cold rolling was investigated, and the effects of deformation, heating temperature and heating rate on austenitic grain size and micro-hardness of quenched samples were discussed. The results show that the austenite begins to when heated to 850 °C and the austenite grains grow significantly when heated to 950 °C during rapid induction heating process. With the deformation increasing, the austenite grain size decreases, and the austenite grain refinement weakened when the deformation increases to a certain extent; but the influence of cold rolling on micro-hardness after quenching is not significant. In addition, there is little effect of heating rate on the 22MnB5 steel austenite with large cold deformation and a certain effect on the micro-hardness after quenching.
Microstructure and Mechanical Properties of 22MnB5 Steel with Different Heat Treatment
Authors: Liu Hong Wei , Zhao Hong Yun , Yu Jing Bo
Published: December 2014

Microstructure and mechanical properties of 22MnB5 Steel were analysis with different heat treatment experiment. The result show that the martensite lath with water cooling become smaller than that with metal die cooling, The lath martensitic microstructure is disappeared with die cooling & tempered specimen. The tensile strength reaches the highest 1645.34MPa by water cooling, but the plastic strength product is lowest. Q&P and die cooling & tempering process can improve the elongation of 22MnB5 with a small amount of tensile strength decrease. The plastic strength product reaches the highest of 20312.74MPa•% by die cooling & tempering method.
Microstructure and Mechanical Properties of 22MnB5 Hot Stamping Part
Authors: Zhang Peng , Wang Gang , Pan Chun Cheng , Ren Xiao Qi
Published: December 2014

Microstructure and mechanical properties of different area of 22MnB5 hot stamping part were analysis by experiment. The results show that the maximum tensile strength reaches 1578MPa at bottom surface area, and the elongation is at the region of 8.5~12 with die cooling area, and the area of bottom surface has higher tensile strength than that of side wall area. Martensite is formed with die cooling, and tempered martensite and undissolved ferrites were found at side wall area. The microstructure of area with air cooling is composed of ferrite and pearlite, and a small amount of martensite.
Development of Niobium Alloyed Press Hardening Steel with Improved Properties for Crash Performance
Authors: Jian Bian , Wang Li , Mohrbacher Hardy , Lu Hong Zhou , Wang Wen Jun
Published: December 2014

Press hardening steel has become a much used material in car body manufacturing due to its excellent safety and lightweight potential. In some recent car models press hardening steel has reached already a weight share of more than 20% in the body structure while it is estimated that it could reach even around 40% in the future. However conventional press hardening steel based on the alloying concept 22MnB5 was designed originally not for automotive application. In spite of the high strength level, press hardening steel has generally low toughness due to the relatively high carbon content and its martensitic microstructure. Particularly important is the ductile-to-brittle transition temperature at low temperature, which might lead to unexpected failure in cold climate regions. Furthermore, hydrogen embrittlement is a major concern in press hardening steel as previous results indicated that only a few ppm of hydrogen could induce delayed cracking. Generally it is important that impact energy should be absorbed by the material to avoid unexpected disintegration of the structure. This material capability is usually characterized by the toughness. All these characteristics have not yet been systematically investigated in press hardening steel. Consequently, no attempts have been made to optimize conventional press hardening steel for obtaining better toughness, lower ductile-to-brittle transition temperature and reduced sensitivity to hydrogen induced cracking.A generally proven approach of improving the resistance against brittle failure in high strength steel is the refinement of microstructure, which can be efficiently achieved by Nb microalloying. This paper will introduce modified alloy designs for press hardening steel and explain fundamentally the metallurgical effects of Nb microalloying on the improvement of crack propagation resistance, bendability and delayed cracking behavior induced by hydrogen penetration in press hardening steel. The results reveal better toughness, improved bending behavior and increased resistance against hydrogen embrittlement.
The Comparative Study on Dynamic Flow Behaviors of Bullet-Proof Steel Using Various Constitutive Models
Authors: Zhao Yan , Ma Ming Tu , Jin Qing Sheng
Published: December 2014

In this paper, the dynamic tension of bullet-proof steels processed by hot stamping are tested on MTS810 and Hopkinson bar, in which four types of steels (B1, B2, C1 and C2) are used. For each sample, the flow behavior is predicted via Johnson-Cook (JC), Modified Johnson-Cook (MJC) and Cowper-Symonds (CS) models on the basis of experimental data, respectively, and the calculation method is also introduced. After that, the errors between prediction of each model and experimental data are analyzed and discussed. As a result, the most appropriate constitutive model for dynamic flow behaviors of bullet-proof steel is proposed. Moreover, our in-house software has been developed for calculating, comparing and selecting typical constitutive models for dynamic flow behaviors of materials, which has the functions of parameters input and output, curve plotting and data storing. The work carried out in this paper will be beneficial for accurate simulation of materials deformation.
Development of Mechanical Properties of Steel Fibers Reinforced High Strength Concrete
Authors: Vogel Filip , Holčapek Ondřej , Jogl Marcel , Kolář Karel , Konvalinka Petr
Published: December 2014

This article deals with time development of basic mechanical properties of steel fibers reinforced high strength concrete (FRHSC). The basic mechanical properties were studied at different age of the fiber reinforced high strength concrete, exactly at the age 12, 15, 18 and 21 hours and 1, 2, 3, 7, 14, 21 and 28 days. The compressive strength was determined by using cubic specimens (100 x 100 x 100 mm). The tensile strength in bending and fragment compressive strength after bending were determined by prismatic specimens (40 x 40 x 160 mm). Bulk density were determined too. The comparison of mechanical properties of fibers reinforced high strength concrete and high strength concrete is in conclusion of this article.
Latent Heat Storage Plaster: Lab-Scale Experiment and Simulation
Authors: Ostrý Milan , Charvát Pavel , Klubal Tomáš , Klimeš Lubomír
Published: December 2014

Energy storage can even out mismatches between the demand and supply of energy, thereby improving the system performance and reducing the cost of building operation. The energy storage is a key issue in the wider use of renewable energy. The experiments carried out at Brno University of Technology focus on the latent heat storage techniques for application in radiant heating and cooling of residential and office buildings. The latent heat storage techniques utilize Phase Change Materials (PCMs) as a heat storage medium and thus allow for the reduction of the amount of heat storage material due to the high heat storage density per volume or weight. In the past, much attention was paid to encapsulation of PCMs. The PCMs undergo phase change from solid to liquid and vice versa during a heat storage cycle and there is a risk of leakage of the PCMs to the building material or indoor environment. The microencapsulated organic PCMs in a mixture with gypsum plaster were used in the investigations described in this paper. The investigations involved both lab-scale experiments and numerical simulations.
Quality Characterization of Iron Dust Exhaust Thermal as Alternative Ceramic Coating Raw Materials in a Brazilian Company
Authors: dalla Valentina Luiz Oliveira Veriano , Folgueras Marilena Valadares , Knop Wanessa Rejane , do Nascimento Maria Cristina Pacheco , Prates Glaucia Aparecida
Published: December 2014

As the raw materials used in the ceramic materials manufacturing are natural, it is important to use them as a alternative materials, thus decreasing the elements demand taken from nature. This paper aims the characterization of foundry solid powder exhaust from a brazilian company located in Joinville - SC as an alternative raw material for ceramic coating by X-ray diffraction (XRD), thermal analysis (DSC) and thermogravimetric (TG). The dust depletion is caused in the manufacturing mold sand process, when the bentonita (clay), silica sand and coal during the metal parts production are mixed in green sand production. The raw materials were characterized through X-ray diffraction (XRD), thermal (DSC) and thermogravimetric analisys (TG). The atomized powder thermogravimetric analysis curve shows three intervals associated with the mass loss and it is typical of clay commercial application.
Eccentric Loading Condition Analysis of 1MN Dead Weight Force Standard Machine
Authors: Yu Li Juan , Li Gao Fei , Lei Tao , Chen Xiao Bo
Published: December 2014

With the development of science and technology , the position of the strength measurement[1] in national economic development is more and more important, In recent years, along with the computer technology, electronic technology and the development of numerical control technology, force standard machine also obtained the rapid development[2-6],dead weight force standard machine strength measuring accuracy is the highest power source device by far, in the process of weight loading, considering the axial load affect the performance of the whole machine and in order to guarantee the machine safe and reliable, it is necessary to eccentric loading conditions for mechanical properties analysis.
Characteristics Analysis and Optimization of Flying-Wing Vehicle Structure
Authors: Zhou Hong Xia , Liu Bin
Published: December 2014

To study structural characteristics of flying-wing vehicle, static and dynamic model of half wing span, static and dynamic model of all wing span, optimization model were established. Based on associated static test and ground resonance test data, these models were modified to implement static, dynamic and optimization analysis. Results demonstrated that structural bending and torsional deformations are mainly at outer wing surface. Torsion at inner wing is positive, while torsion at outer wing is negative. Total spar axial force along the wing span increases gradually from inner wing to outer wing and then decreases gradually after reaching the inner-outer wing interface. After axial force is transmitted to the inner wing, it is going to concentrate at the rear spar obviously. Structural bending rigidity and torsional rigidity satisfy requirements of both static force and flutter, without flutter problem of main structural mode. Viewed from the optimization size, ±45° and 0° skin at inner-outer wing turn thickens significantly. This can increase structural bending and torsional rigidity, which is good for satisfying multiple constraints comprehensively.