bluuebunny/crossref_metadata_2025 huggingface dataset:
CFD modelling of the condensation, evaporation, coagulation and crystallization processes in the cooling tower emissions
Authors: Ershov M I , Tuponogov V G , Abaimov N A , Gorsky M A
Published: November 2021

The aim of the paper is to develop the CFD model for the environmental impact assessment of the cooling tower. The methods applied for this problem are the single-phase turbulent multispecies flow modelling with the DPM Lagrangian particle tracking. The simulations have been carried out in the steady state SIMPLE solver using the ANSYS Fluent software. User Defined Functions have been defined to enhance the accuracy and versatility of the modelling approach in terms of turbulence, fog formation, evaporation, coagulation and crystallization modelling. The Chalk Point cooling tower experiment, laboratory tests with freezing droplets and analytical correlations are used to verify the customized parts of the new CFD model. The arbitrary small-town geometry is used to demonstrate the simulation capabilities of the fog and drift deposition as well as the temperature and relative humidity values near ground and buildings. The results indicate that the new CFD model is able to predict the cooling tower plume parameters, icing and salt contamination risks as well as drift deposition.
Investigation of the direct-flow burners and nozzles arrangement at the direct-flow-vortex coal combustion in a furnace with solid slag removal
Authors: Fomenko M V , Prokhorov V B , Fomenko N E
Published: November 2021

The paper presents results of the furnace aerodynamics investigation using direct-flow burners and air nozzles (DFBAN) with solid slag removal (SSR). The studies were performed using the computational fluid dynamics software ANSYS Fluent. The paper includes recommendations for the development of effective solid fuel combustion schemes with DFBAN, methods for researching and optimization of the combustion aerodynamics with the use of DFBAN, optimization criteria, initial data for the study. The scheme for burning Kuznetsk lean coal with the use of DFBAN and SSR was developed. Several series of calculations were performed for the developed scheme. In these calculations, the dependencies of the indicators of efficiency, furnace ecological safety and reliability on the nozzles and burners positions, which are located in the first zone of the scheme, were found. The first stage of the optimization of the developed scheme burning solid fuel with the SSR was made.
Determination of heat transfer criterial equation when cooling aluminum ingots
Authors: Gorshenin A S , Krasnova N P , Rakhimova J I
Published: November 2021

A big problem when casting aluminum ingots is the uneven structure formation, which leads to an increased rejection of products. Nonequilibrium structure elimination is carried out by heat treatment. To obtain the required aluminum ingots’ physicochemical properties, it is necessary to know the conditions of heat transfer between the ingots and the cooling air, i.e. a mathematical model of conjugate heat transfer is needed. The mathematical model obtained by the authors makes it possible to analytically investigate the ingots temperature and cooling air during heat treatment. This mathematical model assumes the heat transfer coefficient calculation. The existing criterion equations for determining the heat transfer coefficient have a drawback - the heat transfer coefficient according to these equations is calculated in circular channels, while heat transfer between aluminum ingots and air occurs in rectangular channels. The article describes the criterion equation identification for heat transfer, used in the analytical study, by the data of the experimental study.
Aerodynamics and convective heat transfer processes in cyclone chambers with external recirculation of gases
Authors: Konoplev M , Onokhin D , Zagoskin A , Karpov S
Published: November 2021

The paper presents the results of an experimental and theoretical calculation study of aerodynamics and convective heat transfer on the side surface of cyclone recirculation furnace devices. The possibility of controlling the main aerodynamic characteristics without changing the geometric parameters of the cyclone devices by organizing external gas recirculation is shown.
Investigation of boiling heat transfer in microchannel of water and isopropanol
Authors: Kuzma-Kichta Yu A , Lavrikov A V , Shustov M , Kustova E A , Ivanov N S , Kuleshov E A , Kiselev A S
Published: November 2021

Boiling curves of distilled water and isopropanol in 12.5x3x0.2 mm microchannel with rigid inlet and outlet lines are obtained. Critical heat flux is calculated for isopropanol by using the previously obtained correlation for water.
Research of condensation induced water hammer under filling a horizontal pipe with subcooled water
Authors: Volkov G J , Melikhov V I , Melikhov O I , Nikonov S M , Selkin S S
Published: November 2021

Experiments at the KGU test facility, devoted to condensation induced water hammers (CIWH) were analysed with the WAHA code. Test section of the KGU test facility is slightly inclined horizontal pipe of 3 m length and of 64 mm inner diameter. Subcooled water was supplied to the pipe inlet, pipe outlet was connected to separator vessel. Upper part of separator vessel was connected to steam source. Experiments were performed for different system pressure, different water subcooling and different mass flow rate of water supply. The performed experimental study of CIWH showed that in the investigated range of parameters, the development of CIWH occurs in different ways. At the stage of water propagation along the filled with steam horizontal pipe, water hammer was not observed. At the stage of free drainage of water from the outlet end of the pipe, water hammer was realized only when the water was sufficiently subcooled. At the stage of the water level rise in the horizontal pipe, water hammer occurred in all tests. At the last stage of filling the upper part in the separation vessel, there were small water hammers due to the collapses of the remaining steam bubbles. Numerical modelling of these experiments with the WAHA code revealed the shortcomings of the interphase heat transfer model developed for this code, which have a noticeable effect on the numerical solution.
Influence of pipeline geometry on hydrodynamics and heat transfer processes by an example of a ship steam generator
Authors: Mitrofanova O V , Fedorinov A V
Published: November 2021

The theoretical and computational analysis proposed in this work is aimed at identifying the features of thermal and hydrodynamic processes carried out in the steam-generating channels of the ship type water-moderated nuclear power installations. It is shown that the complex geometry of the thermohydraulic tract curvilinear channels of the steam generating system has a significant effect on the efficiency of the transport nuclear power installation. In addition to the formation of large-scale vortex structures and swirling flow in the pipeline, the phenomenon of the swirling flow crisis is revealed, under which the low-frequency component of the acoustic spectrum is enhanced. The scientific and applied significance of the proposed research is associated with the need to ensure a wide range of operational changes in efficient and safe operation power modes of icebreaker nuclear power installations. The research, aimed at developing the principles of physical and mathematical modeling of complex vortex flows, is necessary to optimize the design parameters of the thermal power equipment elements of new generation ship nuclear power installations in order to ensure increased safety and reliability of their operation.
Numerical simulation of fuel staged swirl combustion in the invert furnace of boiler on advanced ultra-supercritical steam parameters
Authors: Prokhorov V B , Chernov S L , Kirichkov V S , Kaverin A A , Fomenko N E
Published: November 2021

The paper considers the schemes of Kuznetsky lean coal combustion for the M-shaped boiler. With such a boiler profile, it is possible to significantly reduce the length of main steamlines, which is especially important for the advanced ultra-supercritical parameters of the superheated steam. The furnace in this boiler unit is performed downward (invert). In this work, the aerodynamics of 6 combustion schemes was simulated by means of computational fluid dynamics. All considered schemes were designed on the basis of direct-flow burners and nozzles. For the most aerodynamically reasonable scheme the thermal processes in the boiler furnace firing Kuznetsky lean coal have been simulated by means of computational hydrodynamics. The simulation results showed a high efficiency of fuel burnout: loss due to unburned combustible equaled 0.1%, carbon-in-ash loss equaled 0.8%. Carbon monoxide concentration at the furnace outlet in conversion to excess air equal α = 1.4 amounted 226 mg/m3, the nitrogen oxides concentration in the flue gases (in conversion to normal conditions) equaled 424 mg/m3. It is appropriate to use the results obtained in this research in the development of new solid fuels combustion schemes.
3D-LDA diagnostics of a swirled flow in the model of an improved four-vortex furnace
Authors: Yu Shadrin E , Anufriev I S , Alekseenko S V
Published: November 2021

The three-component Laser Doppler Anemometry method (3D-LDA) was used to study the internal aerodynamics of an experimental model of a promising furnace with a four-vortex scheme for burning coal fuel. Distributions of the averaged velocity and velocity fluctuations are obtained. There are no the pronounced peaks in the spectrum of velocity fluctuations, so we can speak about the stability of the investigated flow. The studied model is characterized by a high level of velocity fluctuations, provided for effective mixing of the pulverized coal mixture in the combustion chamber of the furnace.
Kinetic approach to solution of evaporation-condensation problems taking into account multi-particle interactions in liquid
Authors: Shishkova I N , Kryukov A P
Published: November 2021

The presented work is devoted to the study of heat-mass transfer in vapor and liquid, taking into account multi-particle interactions in the condensed phase. An appropriate numerical procedure is proposed to solve the kinetic equation, both in the vapor and in the liquid. Using this approach, the problems of thermal conductivity in liquid argon, as well as the problem of evaporation-condensation, are solved.
Experimental efficiency evaluation of the of various geometry twisted bands for heat transfer intensification in the heat-exchange channels of a nuclear power unit equipment
Authors: Sobornov A E , Dmitriev S M , Ryazapov R R , Mamaev A V , Kotin A V
Published: November 2021

The paper is devoted to experimental study of heat exchange and pressure drop of channel with various geometry twisted bands. The studies were carried out in the range of operating modes parameters of the nuclear power units’ heat exchange equipment. The three different designs of intensifiers are presented in the paper. The values of heat transfer coefficient and pressure drop are obtained. The dependences of the Nusselt number (Nu) on the Reynolds number (Re) were calculated. The comparative analysis of intensifiers is made. The efficiency factor was also calculated on experimental data. The most optimal geometry form of intensifier was selected.
Studying of the characteristics of a single bubble under subcooled liquid boiling
Authors: Vasil’ev N V , Zeigarnik Yu A , Khodakov K A , Vavilov S N , Nikishin A S
Published: November 2021

An experimental study of the characteristics of single (solitary) bubbles obtained by means of focused laser heating of the surface during the boiling of two subcooled liquids with significantly different properties: water and refrigerant R113 has been carried out. To obtain the most complete detailed information, the technique of synchronized high-speed video filming of the process in two mutually perpendicular planes with a frame rate of up to 150 kHz was used. It is shown that during the boiling of a subcooled liquid, the main mechanism of heat removal from the bubble dome into the surrounding liquid is an unsteady heat conductance. Differences in the behavior of solitary vapor bubbles in the case of boiling of two liquids (water and refrigerant R113) are shown.
Features of intensive evaporation of liquid-metal steel drops heated in a high-frequency inductor
Authors: Vinogradov D A , Glazkov V V , Ivochkin Yu P , Kubrikov K G , Teplyakov I O , Sinkevich O A , Borodina T I
Published: November 2021

The paper presents the results of experimental studies of the processes of intense melting in air of samples (solid balls) made of metals, primarily various steels. It is shown that the heating of some steels is accompanied by intense sparking - the ejection of small secondary droplets (sparks) from the primary droplet heated up to 2500 K into the surrounding space. A possible mechanism of this process is proposed and described at a qualitative level. Possible reasons for the explosive fragmentation of secondary droplets are indicated and experimentally confirmed. The vibration process of molten samples shell, caused by the vortex motion and evaporation of the melt inside the droplet, is described. The influence of spark formation on the stability of the induction melting process is demonstrated.
Conjugated Heat Exchange in Heat Treatment of Aluminum Ingots Simulation
Authors: Gorshenin A S , Rakhimova J I , Krasnova N P
Published: November 2021

Casting aluminum to obtain semi-finished products - round ingots, due to uneven cooling in the mold, leads to various defects that affect further machining. To eliminate such defects, heat treatment is carried out - homogenization annealing. One of the homogenization important stages is the cooling of the ingots after heating at a rate that does not lead to the ingot quenching. The cooling medium is air. Knowing the conditions of heat exchange between the cooling air and the high-temperature aluminum billet makes it possible to obtain the ingot’s necessary physical and mechanical properties. The article describes the developed mathematical model of conjugate heat transfer during homogenization annealing of aluminum ingot. It allows analytically calculating the temperature of the ingots depending on the cooling time. To verify the data obtained by the mathematical model, the conjugate heat transfer in the ANSYS program was simulated.
Calculation Method of Working Rotational Angle of Automobile Transmission System and Its Applications
Authors: Li Yongzhuo , Lang Chunyan , Tian Zilong , Chen Zhiyuan
Published: November 2021

The working state and operating parameters of the automobile transmission system play a key role in the vehicle noise and vibration performance. Based on the basic calculation method of relative rotational angle, this paper proposes two methods for calculating the working rotational angle and torsional stiffness of the transmission system, which can effectively obtain the key information of the transmission system under the vehicle operating state. The working rotational angle, whose initial angle should be corrected by the average angle in the neutral gear coasting condition, can reflect the actual working state of the torsional vibration damper effectively. And the accuracy of the linear torsional stiffness obtained will be above 90%. Both simulation and experimental analysis results show that these two proposed application methods have high calculation accuracies and engineering feasibility.
Design and Application of Spiral Wound Gasket Sealing for Big Opening Flange for High Temperature and Pressure Vessel
Authors: Zhai Lihong , Li Xun
Published: November 2021

Metallic spiral-wound gasket sealing are generally applicable for the service conditions, which are subject to the periodic temperature and pressure changes, shocks or vibrations. The nominal size of the largest spiral wound gasket of flanges is according to the provisions of HG/T 20631; those more than this specification are in the scope of non-standard parts, which require customization and manufacturing. This paper aims for introducing the successful experience of the first application of customized for non-standard spiral-wound gasket sealing of the large opening flange used for pressure vessel which bears high temperature and high pressure. The paper demonstrated the basic principle and critical points for the design and application of customized non-standard spiral-wound gasket sealing for the large opening flange and provided the valuable reference of actual application experience for the design and manufacturing of similar components. This paper presents the experiences summary in the study field and provides valuable reference of actual application experience for the design and manufacturing of similar components.
Research Progress of Springback in Multi-Point Forming of Sheet Metal
Authors: Li Xinqi , Hu Shicheng
Published: November 2021

In the manufacturing of sheet metal, multi-point forming replaces the traditional integral die with discrete basic body groups to adjust the height of each basic body and form the required three-dimensional curved surface, thereby facilitating flexible processing. Multi-point forming is the most common approaches for the manufacturing of sheet metal but can cause serious shape distortion due to springback phenomena. In this paper, key research on springback is categorized and analyzed from three aspects: springback theory, springback numerical simulation analysis, and springback control, followed by summary of the current research status and outlook on promising future research directions of springback in multi-point forming springback. And the conclusion is drawn: in the future, multi-point forming of sheet metal using high-frequency ultrasonic excitation for springback control during the forming process coupled with artificial intelligence for springback compensation control will be a promising research direction for controlling springback in the multi-point forming of sheet metal.
Study on Bearing Mechanism of Split Grouting Pile Based on Finite Element Simulation
Authors: Wang Jinman , Li Shaofei , Zhou Mingru , Zhong Lin , Chen Yiming
Published: November 2021

In order to realize the directional and controllable splitting of splitting grouting, the field grouting test was carried out. Using a new grouting pipe designed, the splitting direction and size of the branch vein are effectively controlled through the control of grouting pressure and grouting amount. In order to explore the bearing characteristics of split grouting pile and provide necessary parameters for the design of split grouting pile composite foundation in engineering practice, the field static load test and indoor geotechnical test of split grouting pile are designed, and the ultimate bearing capacity of single pile and necessary soil parameters are obtained. In order to make up for the limitations of field static load test, the three-dimensional finite element model of pile, soil and branch vein of split grouting pile is established by using the finite element analysis software ABAQUS. The finite element analysis results are compared with the measured values of field test, and the variation laws of pile shaft axial force, stress and displacement of branch vein at different depths, pile side friction, etc. are further explored, Through these changes, the interaction and load transfer mechanism between pile and soil are analyzed, which provides a reference for optimal design.
A Review of Dynamic-Tribological Simulation Methods for Sliding Bearings in Internal Combustion Engines
Authors: Tong Dehui , Diao Ziyu , Sun Nannan , Du Xiangning , Zhang Yanyan , Liu Zhentao
Published: November 2021

The problem of friction reduction and wear resistance of sliding bearings is one of the key factors in determining the overall performance of internal combustion engines. This paper investigated and summarized the theoretical and simulation models of multi-body dynamics of crankshaft system, tribology of sliding bearings, and the wear calculation methods of the shaft-bearing friction pairs. Existing studies show that the dynamics model, hybrid lubrication model, and the friction and wear models request to be upgraded by comprehensively considering the material, structure, manufacturing process, working conditions, and etc. Based on the research status and existing problems of the above analyses, this paper summarizes the simulation models applicable to the field of dynamics and tribology of sliding bearings and presents the prospects for optimization of wear calculation methods for sliding bearings.
Design and Implementation of a High Precision Stewart Platform for a Space Camera
Authors: Liang Fengchao , Tan Shuang , Fan Jiankai , Lin Zhe , Kang Xiaojun
Published: November 2021

In order to design and implement a high-precision Stewart platform to precisely adjust the position and posture of the secondary mirror of a space camera, the following measures were taken: firstly, the inverse mathematical model and ADAMS parametric model of the Stewart platform are established, which are the basis of structural optimization design; secondly, the structural parameters of Stewart platform are obtained through structure optimization design in ADAMS after determining the objective function; thirdly, a 50nm resolution driving strut based on brushless DC motor, ball screw, grating ruler and PI closed-loop control law is designed, which strongly guaranteed the six degrees’ resolution of the Stewart platform that mainly consist of 6 such high-resolution driving struts; finally, the accuracy of Stewart platform is tested via dual frequency laser interferometer and photoelectric autocollimator, and the test results show that the displacement resolution of the Stewart platform is 0.2 μ m, and the angular resolution is 1”, which meets the requirements of the index. The Stewart platform has been successfully applied to the space camera by tuning the secondary mirror precisely in 6 degrees of freedom in the optical alignment experiment, which lays a solid theoretical and practical foundation for on orbit application in future.
Research on High Precision Rapid Online Measurement System of Crankshaft Based on Multi-station
Authors: Gu Tingting , Qian Xiaoming , Lou Peihuang
Published: November 2021

According to the structural characteristics and production requirements of the crankshaft, the online measurement platform of crankshaft was built. The multi-station assembly line is developed to measure, to mark and to classify the parameters and measurement elements of the crankshaft. In addition, SPC software is designed to perform mathematical statistics and analysis on the measurement information. It can distinguish between normal fluctuations and abnormal fluctuations in the production process, can inform the fluctuation state to determine whether it should be adjusted, can compare the fluctuations and provide direction for improvement. Finally, through multiple measurement experiments, the feasibility and effectiveness of the synchronous measurement scheme and data processing method proposed in this paper are verified. The experimental results show that GR&R is less than 9.3%, and measurement accuracy is less than or equal to 1μm.
Numerical Simulation and Experimental Study on Rotary Cold Extrusion Forming of Screw Rod
Authors: Li Peiai , Wang Baoyu , Wang Jiapeng
Published: November 2021

The rotary cold extrusion forming process is a plastic forming process with very low material loss, especially in the production of hollow screw rods with equal wall thickness. In this work, the rotary cold extrusion forming process of a hollow T2 copper screw rod with a wall thickness of 4 mm and solid T2 copper screw rod was verified by experimental method. The finite element simulation software Deform-3D was also used to simulate the rotary cold extrusion forming process of the screw rod. The effects of the die with different heights of the working belt and the different wall thickness of the billet on the eccentricity, extrusion force, and forming torque in the forming process of the screw rod were studied. The results show that it is feasible to process hollow and solid T2 copper screw rods with equal wall thickness by rotary cold extrusion. With the increase of die working belt height, the eccentricity of the screw rod becomes smaller and closer to the ideal eccentricity. With the increase of the wall thickness of the billet, the amplitude fluctuation range of the eccentricity of the screw rod gradually decreases. The higher the height of the die working belt, the greater the extrusion force and torque required in the extrusion process, and the more intense the change of torque. These results also provide theoretical guidance for the production practice and lightweight transformation of the screw pump rotor.
Mathematical Principle Analysis of Separation Point Prediction
Authors: Yue Peng , Zhang Jinghui , Peng Dewei , Wei Sibei
Published: November 2021

During the development of fluid mechanics, fluid separation is an important issue. So far, there is no mathematical formula to reveal and describe the essence of fluid separation. At the same time, due to the high cost and limitation of the experimental method, another method is urgently needed to predict the separation position of the fluid. After axiomatizing fluid mechanics and combining the principle of excited state of quantum mechanics, this paper reveals that fluid separation is a special form of fluid in an excited state, and deduces the state conditions of fluid separation. The research results of this paper provide new ideas for solving problems in fluid separation and engineering applications.
Vibration Analysis of Hub Motor Based on ANSYS
Authors: Li Lin , Yao Xueshi , Zhang Xinghua , Zhong Xiaohua , Xiao Wanshen
Published: November 2021

The hub motor is designed with multidirectional excitation and Halbach Array, which includes inner rotor, left and right stator, outer stator, encoder and rotary transformer. The rotor consists of an axial disk and a top ring. The rotor’s permanent magnets are affixed to the left and right sides of the disk and to the outside of the top ring. The permanent magnets on the rotor adopt a Halbach Array. The three stators have not the iron core and they are arranged outside the rotor to form a three-way closed loop. The motor has high power density, high torque density, low heating, strong adaptability and no cogging effect. It is suitable for electric car control. On this basis, the dynamic equation of the hub motor is established, the vibration mode of the rotor system is analysed, when the inner rotor’s speed is 18000rpm. By use of the solid model, the hub-rotor’s accurate dynamics solution can be obtained. In the future, the effect of vertical coupling vibration will be investigated for its ride comfort and safety.
Design Based on Changing the Bucket of Small Hydraulic Excavator to Clamp Brick Machine
Authors: Hu Huali , Chen Weizhen , Ji Rui , Ban Huadian , Chen Bingsen
Published: November 2021

Small hydraulic excavators have the characteristics of multi-function and wide application range. It is an important mechanical equipment widely used in mechanized construction. It can not only be used for excavation of earth and stone, but also plays an irreplaceable role in various engineering constructions. Moreover, through the replacement of working devices, it can also be used for various operations such as lifting, loading, grabbing, piling, and drilling. This article takes a small excavator as an example. By disassembling the original bucket, the newly designed brick clamping mechanism is installed in the position of the bucket, so as to realize the purpose of clamping or moving bricks and increase the scope of use of the original excavator.
Research on Erecting Joint and Dynamic Characteristics of Four-Hinge-Point Dual-Drive Missile
Authors: Shi Chunjuan , Sun Zhiyong , Feng Gang , Cheng Yongqiang
Published: November 2021

In order to improve the quick reaction ability and stability of the missile launching erecting system, the driving mode of the erecting joint is optimized. A four-hinge-point double-driving erecting joint is proposed and the mechanical model is established, the force and time of erecting cylinder are calculated by Matlab, and compared with two kinds of three-hinge-point joint. The results show that the response speed of the four-hinged double-drive erecting joint is fast, the erecting process is fast in the early stage and stable in the later stage, and the elongation and the erecting cylinder force are between two kinds of three-hinged joints, the four-hinge erector can not only combine the advantages of the three-hinge front-mounted and rear-mounted structure, but also realize the aim of compatibility design and improve the rapidity and stability of the missile erector, it can provide an important basis for the structural design of missile launcher.
Geometric Segmentation of 3D Scanned Surfaces for Multi-Sensor Coordinate Metrology
Authors: Yu Zhiqiang , Zhang Mao , Xiao Jiaoyu
Published: November 2021

In modern industry, multi-sensor metrology methods are increasingly applied for fast and accurate 3D data acquisition. These method typically start with fast initial digitization by an optical digitizer, the obtained 3D data is analyzed to extract information to provide guidance for precise re-digitization and multi-sensor data fusion. The raw output measurement data from optical digitizer is dense unsorted points with defects. Therefore a new method of analysis has to be developed to process the data and prepare it for metrological verification. This article presents a novel algorithm to manage measured data from optical systems. A robust edge-points recognition method is proposed to segment edge-points from a 3D point cloud. The remaining point cloud is then divided into different patches by applying the Euclidean distance clustering. A simple RANSAC-based method is used to identify the feature of each segmented data patch and derive the parameters. Subsequently, a special region growing algorithm is designed to refine segment the under-segmentation regions. The proposed method is experimentally validated on various industrial components. Comparisons with state-of-the-art methods indicate that the proposed method for feature surface extraction is feasible and capable of achieving favorable performance and facilitating automation of industrial components.
Study on Counter-Roller Spinning Technology of Large Diameter Aluminum Alloy Cylindrical Parts
Authors: Huang Tao , Lu Bo , Luo Wei , Wang Jian , Guo Yaming , Ma Lijun , Ma Xiaoliang , Ma Shuai
Published: November 2021

Counter-roller spinning is an optimal process for forming large diameter cylindrical parts. In this paper, the finite element model of large diameter aluminum alloy cylindrical parts Counter-roller spinning is established, the regularities of distribution of stress and strain of each pass of the workpiece is obtained, as well as the influence of the roller feed ratio and fillet radius on the forming quality is obtained. The process parameters were optimized by grey correlation analysis. In this paper, for large diameter aluminum alloy cylindrical parts, the optimal spinning parameters are obtained as follows: the feed ratio is 1.0mm/r, the rotary roller fillet radius is 8mm. The results of numerical simulation are consistent with those of process test. The technological parameters can be used to guide the actual production of such large diameter cylindrical parts.
Research on the Operational Modal Prediction of Dry Gas Seal System Based on Response Surface Method
Authors: Liu Yun , Liu Quanxing , Yin Guofu , Luo Xiaofeng
Published: November 2021

The cross power spectrum function is used to realize the operational modal analysis and identification of the dry gas seal device system through the multi-reference point least squares complex frequency domain method. The steady state diagram and mathematical indicators MAC, MPD, MPC, MOV and MIF are used to verify the modal results. At the same time, based on the response surface method, with two different operating conditions of medium pressure and rotating speed, modal direction and modal order as the response surface variables, a time-varying modal recognition model is established. Through the Full Factorial experiment design, Box-Behnken experiment design and Central Composite experiment design, the suitable variable sample points are formed. A complete quadratic polynomial response surface model of the system operational modal parameters is established. The complex correlation coefficient, the modified complex correlation coefficient and the root mean square error are used to verify the effectiveness of the response surface model. It provides new method and technical support for realizing time-varying modal identification in this paper.
Dynamic Knowledge Graph Based Construction of Quality Infrastructure System for Non-API Oil Country Tubular Goods
Authors: Chen Xiangpeng , Xie Juntai , Gao Jianmin , Wang Rongxi , Jiang Jiandong
Published: November 2021

With the deep exploitation of oil and gas resources, the non-API oil country tubular goods (OCTG) adapted to specific environments are used widely. Therefore, how to effectively characterize the quality connotation of non-API OCTG to ensure their quality has become a challenge for the petroleum industry. We propose a dynamic knowledge graph of Quality Infrastructure (QI) to solve the problems of the diversity of non-API OCTG quality influencing factors, the concealment of the relationship, and the ambiguity of the mechanism of quality improvement. Firstly, a knowledge graph ontology framework of quality infrastructure is constructed, which realizes the effective combination of product characteristics and quality basic elements. Secondly, based on the professional dictionary in the field of OCTG, entity recognition adopts the entity recognition method of LDA-BiLSTM-CRF, which effectively improves the recognition accuracy of professional vocabulary. Finally, the relationship between entity types is defined as the edge of the knowledge graph; the graph embedding method is used to supplement the edge connection and calculation weight of the knowledge graph. The QI knowledge graph constructed with this technology can well describe the quality connotation of non-API OCTG, and provide opinions and methods for guaranteeing and improving the quality of non-API OCTG.
Research on Stability of Sand Core Handling Robot System Based on PID Control
Authors: Lin Xianxin , Li Guojin , Su Qian , Li Xi
Published: November 2021

When an industrial robot uses a gripper with half hardness and flexibility to carry a hollow sand core, mechanical vibration will cause the gripper to grasp the sand core unsteadily or cracks in the sand core due to excessive pressure. In this paper, the mathematical model is constructed based on the elements such as gripper structure, clamping pressure and mechanical vibration, the system stability is analyzed, the PID controller is added for correction, the parameter values of Kp, Ti and Td are set by Ziegler-Nichols method, the transfer function of PID controller is obtained, and then the corrected system function is calculated. The dynamic response performance of the system is simulated and analyzed by Matlab / Simulink, the parameters in the PID controller are adjusted, and the overshoot of the system is reduced from 85% to 25%, which effectively reduces the impact of mechanical vibration interference on the sand core and realizes the optimal control of the system.
Low Viscosity Epoxy Structural Adhesive Cured at Room Temperature for Crack Repair of Subway Tunnel
Authors: Xiao Ming , Sun Xiaojiang , Rong Huaqing , Bi Shuguang , Tang Jiagong , Luo Xianmeng , Ran Jianhua
Published: November 2021

Epoxy structural adhesive has good mechanical properties, especially high adhesion, low shrinkage rate, and high stability, widely used in steel plate reinforcement, crack repair, bridge splicing, and concrete bonding, etc. However, due to the high cross-linking density and high internal stress after curing, its shortcomings, such as brittleness, the poor performance of fatigue resistance and heat resistance, limit its application in special track engineering. In this work, two kinds of epoxy structural adhesives (EPA-1, EPA-2) with low viscosity and room temperature curing were synthesized by selecting different bisphenol A epoxy resin and active diluent as component A and modified amine curing agent as component B. The results showed that EPA-1 and EPA-2 presented significant toughness compared with the classic construction adhesive (AralditeXH160). The yield strengths of EPA-1 and EPA-2 were 4.88 MPa and 13.13 MPa, and the shear strengths were 11.93 MPa and 13.08 MPa, respectively, showing good adhesive properties. In addition, the viscosities of EPA-1 and EPA-2 were 127 mPa·s and 308 mPa·s, respectively, and their decomposition temperatures were all above ∼280 °C, which indicated that the self-made epoxy structural adhesives could be used for the repair of cracks in the vibration subway tunnel.
Selective Metallization on CFRP Composites by Laser Radiation and Electroless Plating
Authors: Li Jiafeng , Lin Pengting , Sun Haoran , Li Xinxin , Sang Jie , Wang Xuguang , Li Qiang , Jin Yu , Zhang Ligong
Published: November 2021

Selective metallization of carbon fiber-reinforced polymer composites (CFRP) was conducted by laser ablation with 1064 nm laser radiation and electroless plating in nickel solution. A rough caterpillar-like structure and polar surface with high property of absorption and anchoring for active seeds were produced by laser ablation. The laser treatment produce had a pronounced influence on nickel deposition. After immersed in nickel solution for 150s, a homogeneous and dense nickel film was selectively deposited on the laser treatment area of CFRP by electroless plating successfully. The Ni plating exhibited excellent adhesion on the CFRP. The technique in this study would widespread the application of CFRP in the area of spacecraft microwave components and waveguide antenna.
Strain Sensing Elastic Core-Spun Yarns Based on Long Silver Nanowires
Authors: Jia Liping , Zeng Qi , Zhu Quanquan , Cai Runxuan , Guo Wei , Ran Jianhua , Bi Shuguang , Li Shiwei
Published: November 2021

Strain sensing is one of the important functions of intelligent fabric, which can transform the external stress (or strain) into visible electrical signals and monitor the characteristics of human physiology and motion. At present, the flexible strain sensor has low sensitivity, small strain range and unstable performance after repeated stretching. In this work, core-spun yarns with polyurethane (PU) filament as core and long silver nanowires (AgNWs) loaded cotton fiber as shell was fabricated by spinning technology. The results showed that when the loading of AgNWs was 10 wt%, the strain range of the PU/cotton@AgNWs core-spun yarn was 0-60%, the gauge factor of 12.6 was linear, and the strain sensing and mechanical properties were stable after repeated stretching. This strain sensing elastic core-spun yarns constructed by spinning technology could be used as one of the important materials for intelligent wearable devices.
Achieving Mechanical and Conductive Anisotropy in Carbon Nanotubes/Cu Composites
Authors: Enana Rodophe Olivier Diabo , Zheng Zhong , Xing Fang , Tao Jiafeng
Published: November 2021

Cu matrix composites reinforced by Multi-walled Carbon Nanotubes (MWCNTs) were prepared aiming to enhance the mechanical performance of Cu through MWCNTs while preserving its excellent axial conductivity. The microscopic structure, mechanical performance and electroconductivity of the composites were characterized, and the related mechanism was discussed. MWCNTs dispersed uniformly in Cu matrix and arranged in the direction of drawing. The composites showed obvious orthogonal anisotropy. The mechanical properties of the composites increased with the content of MWCNTs. The composite with 10vol.% MWCNTs has the best strength and hardness, which was better than most of data in the literature. However, the highest enhancement efficiency of 3vol.%-MWCNTs/Cu composite was the highest. The main enhancement mechanism was load transmission effects and dislocation. The electroconductivity and thermal conductivity of 5vol.%-MWCNTs/Cu composite parallel to the drawing direction reached the maximum value. The main strengthening mechanism was that Ni-Cu coating on MWCNTs leads to strong interface combination between MWCNTs and Cu, which promotes the electron-phonon coupling and reduces electron or phonon scattering at the interface.
Research on Microstructure and Corrosion Behavior of Zinc-Magnesium Coating by Powder Impregnation
Authors: Liu Qiuyuan , Zhang Wendong , Jiang Juntao , Yue Linjiang , Shen Wei , Liu Xin , Jiang Sheming , Zhang Qifu
Published: November 2021

In order to improve the service life of railway fasteners under various environmental conditions, the Zn and Zn-Mg coating were prepared on the railway fastener gaskets by powder impregnation. XRD and SEM were used to characterize the phase composition, microstructure and morphology before and after the salt spray. The neutral salt spray test (NSST) and the electrochemical workstation were used to characterize the corrosion resistance of the two coatings. Results show that there was a large area of red rust on Zn coating after 480 hours of NSST, while there was no red rust on Zn-Mg coating after 1920 hours of NSST. The impedance of the Zn-Mg coating reached 1015.6 Ω·cm2, about 3.65 times of the Zn coating. Zn-Mg coating’ current density was 3.27 μA·cm−2, which was only 21% of the Zn coating. MgZn2 and Mg2Zn11 phases were easier to formed in Zn-Mg coating due to the infiltration of magnesium, forming a dense and protective layer, thereby greatly improved its corrosion resistance.
Effect of Rare Earth Element La on Corrosion Resistance of Powder Zinc Coating: Experiment and First Principle Calculation
Authors: Xin J P , Zhang S Y , Hu S P
Published: November 2021

Using a combination of first-principles calculations and experimental studies to study the effect of La on the corrosion resistance of Powder sherardizing layer in metal structures. Compared to other sherardizing rare earth elements (Re), La has better adsorption with the iron matrix and has the lowest binding energy on the adsorption surface (111) of the Fe matrix. Therefore, the rare earth element La is added to the powder sherardizing process for the rare earth chemical heat treatment to reduce the defects of the powder sherardizing faults formed, improve the surface uniformity and the quality of the permeation layer. On the basis of calculation, La element was added in the process of powder sherardizing, and the corrosion performance of the formed powder galvanizing layer was studied. After alternating salt spray experiments, the degree of corrosion of the layer is relatively small and the corrosion products are predominantly layered and spherical. Electrochemical tests of the layer show that the corrosion resistance of the layer after the rare earth chemical heat treatment has improved.
Effect of Temperature on Tensile Curve of Polyaspartic Ester Polyurea and Its Activation Energy Analysis
Authors: Zhang Jian , Zhai Junxue , Zhao Xijuan , Lin Jinjian , Wang Qingguo , Du Aihua
Published: November 2021

The influence of ambient temperature on the tensile stress-strain curve of polyaspartic ester polyurea (PAE-PU) was investigated to discuss the yield and breakage mechanism of tensile deformation. Temperature has a significant effect on the tensile stress-strain curve of PAE-PU. At low temperature (27, 40 °C), it shows obvious yield and forced high elasticity. After the temperature exceeds 80 °C, the yield phenomenon disappears and shows high elasticity of rubber: the strain energy and breakage energy are significantly reduced. The yield activation energy of PAE-PU was calculated by yield strain time at different temperatures. It was found that the yield activation energy decreased with the increase of tensile rate. When the tensile rate is 500mm/min, among the activation energies calculated by breakage strength, yield strength and Young’s modulus at different temperatures, the ordinary elastic deformation activation energy is higher, while the yield and breakage activation energy are close and lower. The latter two are close to the hydrogen bond energy and one order of magnitude lower than the chemical bond energy of molecular chain.
Effect of Heat Treatment Process and Composition on Deformation and Damage Behavior of WHA under Detonation Loading
Authors: Tang J J , Liang Z F , Hu X Y
Published: November 2021

The excellent material properties of tungsten heavy alloy (WHA) make it widely used in the military field. When used as killing elements of weapons, its dynamic mechanical properties under detonation loading directly determine the damage effect of weapons, which makes the research on its mechanical behaviors under high pressure and high strain rate loads such as detonation loading of great significance. In this paper, several WHAs with different compositions and processes are selected, and the mechanical properties and deformation and damage behavior under static explosion test are analyzed by combining macro and micro study, so as to provide guidance for the subsequent optimization of the performance design of WHA.
Influence of a High Static Magnetic Field on the Morphology of Primary Al3Fe Phase in Al-3%Fe Alloy
Authors: Jin Fangwei , Ji Xueying
Published: November 2021

It had been done the experiments of the solidification on Al-Fe alloy under a high static magnetic field (10T). The effect of high magnetic field on the morphology of primary Al3Fe phase in Al-3%Fe alloy solidification structure has been investigated by analyzing the microstructures. The experimental results shew that the variation of the morphology of Al3Fe phase was obvious under a high static magnetic field, and them changed to particle-likes and short needles from needle-likes, and they were arranged in chains along the direction of magnetic field to form oriented layered structure. The critical nucleation work reduced and the nucleation rate increased under the applied field, and the magnetic interaction caused by the field can suppress the growth of needle-like Al3Fe phase, both of them resulted in the particle-likes and short needles grains of primary Al3Fe phase to nucleate and grow preferentially. Under the action of magnetic moment and the magnetic interaction force a high static magnetic field, the grains of Al3Fe rotated and then polymerized, and finally formed chain arrangements and layer structures.
Microstructure Evolution and Coarsening of θ′-Al2Cu Precipitates in a Creep Aged Al-Cu-Mn Alloy
Authors: Muddassir Dar Soban , Zhao Yutao , Liao Hengcheng , Kai Xizhou
Published: November 2021

This paper describes the microstructure evolution in a creep aged Al-Cu-Mn alloy using optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Results show the sub-grains formation and accelerated coarsening of θ′ precipitates in creep aged samples. It is observed that at an applied stress of 50MPa, as the creep temperature increases the average length of θ′ precipitates increases and their aspect ratio first increases then decreases. It is also found that after 100h of creep exposure at 200°C/50MPa, θ′ precipitates have grown to an average length of 279nm; at 225°C/50MPa to an average length of 425nm and at 250°C/50MPa they have grown to an average length of 844nm. Coarsening/growth rate of the precipitates is described by Lifshitz-Slyozov-Wagner (LSW) model.