bluuebunny/crossref_metadata_2025 huggingface dataset:
A low stray inductance laminated busbar for series-parallel capacitors
Authors: Yannan GUO , Peng SUN , Yumeng CAI , Zhibin ZHAO
Published: January 2021

In the dynamic characteristics test circuit for high-voltage and high-power power electronic devices, the laminated busbar is the main connecting component. The stray inductance of the laminated busbar is one of the key factors that affect the accuracy of the dynamic characteristics. Therefore, a low stray inductance laminated busbar for series-parallel capacitors is proposed, from the perspective of reducing self inductance and increasing mutual inductance. Through finite element simulation, the result of extracting the stray inductance of the laminated busbar is 4.16nH. Compared with the most basic laminated busbar, this stray inductance is very small.
Simulation Analysis on The Influence of Temperature and Stress in The Plastic Processing of Crystal Germanium
Authors: Bi Jiao long , Shi Guang feng , Shi Guo quan , Gao Ji yu
Published: January 2021

Crystal germanium has the characteristics of high hardness and brittle quality. It is a common material for infrared optical parts. In order to explore the mechanical properties of germanium crystals in plastic processing and the influence of temperature on cutting, FEM software was used to conduct micro cutting simulation on the ultra-precision turning process of germanium crystals, and the cutting force, temperature and cutting energy in the cutting process were analyzed. The results show that the main cutting force and cutting resistance decrease with the increasing of the temperature. By calculating the unit cutting force and the unit cutting resistance, the change of cutting energy is reflected indirectly. By means of normalization of cutting force, the specific gravity of stress and temperature to the cutting process at different temperatures is obtained.
Design and analysis of retractable structure of new quadrotor landing gear
Authors: Xin Huang Bing
Published: January 2021

With the development of equipment level, the requirements for the compact-ness and light-weight of UAV become more and more stringent. In order to solve the problems such as the weight and large volume of the landing gear of the existing four-rotor aircraft, this paper developed a new four-rotor unmanned helicopter landing gear retractable structure based on the existing landing gear. The release process and retractation of retractable structure of the new landing gear are described, and its motion form and attitude are introduced in detail. In this paper, the stress of high strength flexible rope during landing gear releasing and re-tracting is analyzed, and the mathematical model is established. Adams software is used to simulate and analyze the force state of the landing gear leg when the rope is pulling at a constant speed. The results of the dynamic simulation and mathematical model are consistent, that is, the maximum force when retracted to 90° is about 30N (for a single wing). Finally, the finite element simulation software Ansys Workbench was used to carry out strength checking and deformation analysis of the wing, and the rationality of the designed me-chanical structure was verified. The research results of this paper provide a certain basis for the development of landing gear of four-rotor unmanned helicopter.
Effects of physical parameters and time-delay coefficients on the amplitude and frequency bandwidth of saturation controller for a nonlinear beam vibration
Authors: Dai Han , Zhao Yanying
Published: January 2021

This paper is focused on the effects of the physical parameters for saturation control bandwidth and the time-delay coefficient for the saturation control stability. The approximate analytical solutions are obtained when the primary external resonance and 1:2 internal resonance occur simultaneously. The effects of amplitude of excitation, nonlinear feedback coefficients and nonlinear coefficients on saturation control are investigated. It is shown that nonlinear feedback coefficients can enlarge the effective saturation control bandwidth and enhance the dynamic vibration absorber’s suppression. Two nonlinear coefficients enhance the system’s nonlinear phenomenon and remain the same saturation control regions. For the time-delay coefficient, the system begins to appear unstable saturation control regions with only a little time-delay. The increasing time-delay coefficients can enlarge the unstable saturation control regions, it should be avoided.
Effect of the stator tooth thickness on flow characteristics of high shear mixer
Authors: Kwon Cholu , Kim Kwangchol , Pak Unsong
Published: January 2021

Due to the complexity of flow field in high shear mixer, it is very difficult to measure the flow field in full three-dimensional. CFD simulation has become a powerful means in mixer research. In this study, large eddy simulation (LES) was used to simulate the single-phase flow field of a pilot scale in-line high shear mixer with ultra-fine teeth. The research results show that with the increase of the stator tooth thickness, the turbulence intensity and eddy current intensity around the outermost stator increase slightly, and the shear rate area with a larger value change slightly. This means that the stator tooth thickness has a slight effect on the flow field. These results provide important guidance for the design and optimization of high shear mixer structure.
Quantitative research on the contribution of demand-side response to the promotion of renewable energy consumption
Authors: Xiang Meng , Ji Guangya , Zou Yanhui , Dong Zichao , Shao Zhu , Tang Xingzhu
Published: January 2021

Current demand side resources gradually become an important part of promoting renewable energy given, using price, taxes, subsidies and other economic mechanism, encourage users to change electricity behavior, complete with the maximization of expected load curve fitting, to achieve the peak cut, or peak adjustment, to maximize the utilization of renewable energy power generation. Based on the reasonable classification and definition of user types and demand-side resources, this paper constructs a grid load influence degree model of compatible demand-side resources, and quantitatively studies the contribution degree of demand-side response to promoting renewable energy consumption.
An Adaptive Predictive Control Method Based on State-space Model
Authors: Luo Xiaosuo
Published: January 2021

An adaptive state-space model predictive control strategy is proposed for complex industrial processes with nonlinear, time-varying and constrained characteristics. The state-space model obtained by on-line identification algorithm is used as the system model, and the indirect form is used to design the adaptive predictive controller. The controller includes quadratic programming solution to the constraint problem. The effectiveness of the proposed control strategy is verified by the simulation experiment of 2-CSTR process control.
Research on Coordinated Control Strategy of Energy Storage Participating in Primary Frequency Regulation Considering Frequency Deviation Change Rate
Authors: Yang Bo , Weng Liguo , Li Yuelong , Zhang Yanghui , Zhou Chen
Published: January 2021

In order to further improve the performance of primary frequency modulation (PFM) by battery energy storage, a new control strategy is proposed. By analysing the characteristics of virtual inertia response and virtual droop control, the artificial dead zone of energy storage participating in frequency modulation is set based on virtual inertial control to make it respond quickly and improve the characteristics of energy storage to suppress frequency deviation change rate; In this paper, the remaining energy and load disturbance of the energy storage battery are taken as the double inputs, and the fuzzy control strategy is used to derive the function relationship between the virtual droop coefficient and the two inputs to ensure that the charging and discharging power of the energy storage battery is suitable for the actual needs. The load change rate is used to predict the load change at the next moment. Based on this, the coefficients of virtual inertia control and virtual droop control are determined, and the output coefficients of both are optimized to achieve the optimal frequency regulation effect. Three evaluation indexes are proposed to evaluate the control strategy in this paper. Finally, the simulation model is established in MATLAB/Simulink and the case study is carried out in a regional power grid. The proposed strategy can effectively improve the primary frequency regulation of power grid and has positive significance for maintaining energy storage battery.
Study on connection quality of assembled cam after hydraulic expanding
Authors: Lin SONG , Lianfa YANG
Published: January 2021

The cam is an important part of engine exhaust opening and closing. The assembled cam has completely replaced the traditional integrated cam. In this paper, several common methods for assembly effect detection of assembled cam are summarized, and five methods are analyzed and commented from the aspects of measurement form, data form, destructivity, usage scenario and economy. To measure the contact area and residual stress of the fitting surface with the assembled cam, a suitable method is selected, and the research direction is determined.
Optical Wavelength-dependent THz Wave Modulation based on Graphene Coated Germanium
Authors: Li Yuanpeng , Wen Tianlong
Published: January 2021

Optical Hz wave modulator based on semiconductor is broad used in THz imaging area due to convenient to realize. However, for a long time, the laser wavelength influence to the modulation properties is not clear. Germanium and graphene coated germanium upon different laser wavelength (638, 915 and 1550 nm) laser irradiation were investigated to clear the above influence. As a result, the THz wave modulation depth increase with the laser wavelength due to the surface recombination. And the results were proven by discussing the modulation enhancement of graphene coated germanium. In addition, the short wavelength laser would lead to slow modulation rate. As a result, it is a novel method to improve the THz modulation depth and modulation rate by using long wavelength laser.
Design of Screw Type Automatic Apple Juicer
Authors: Wu Changzhong , Ge Fan , Shang Guangchao , Wang Guitao , Zhao Mingpeng , Wu Liang , Guo Hengshuai
Published: January 2021

Based on the actual juicing test, aiming at the problems of low juice yield, easy jam of fruit dregs and difficult cleaning of juicer, a series of researches on automatic Apple Juicer were carried out, and the structure and function of main components were designed and optimized. It mainly includes the design of screw structure for the juicer, the structural design and parameter calculation for the screw rod to increase the pressing force on the fruit during juicing and improve the juicing rate; the design of separable structure for the extrusion cylinder to solve the problem of unsmooth slag discharge and realize the effective cleaning of the internal structure of the juicer. The design can automatically extract apple juice, effectively improve the juice yield, realize the separation of fruit dregs and juice, and automatically carry out effective cleaning, which is suitable for the automatic sales system.
A Potential Domestic Shrimp Deveining Machine Based on Reciprocating Motion of the cutting tool
Authors: Wang Shufan
Published: January 2021

This article proposes a design of a potentially feasible small-size domestic automatic shrimp deveining machine. In this design, a laser rangefinder is utilized to measure the shrimp’s thickness to determine how deep the cutting tool should cut into the shrimp. The specialized cutting tool, which is composed of a blade and a spoon, then cuts the shrimp’s back and exposes the shrimp vein so that the spoon can devein it later. By using SolidWorks and SolidWorks Simulation Animation, this design proves to be practical and has commercial potential.
Mechanical Fault Diagnosis Methods Based on Convolutional Neural Network: a Review
Authors: Zhang Tianzhe , Dai Jun
Published: January 2021

Deep learning is good at abstract features from massive data and has good generalization ability, which has attracted more and more researchers’ attention. The Convolutional Neural Network (CNN) is a classic structure of deep learning and which is being widely and successfully used in the fields of computer vision, target detection, natural language processing, and speech recognition. Based on a detailed analysis of the current status and needs of mechanical system fault diagnosis, this paper introduces the structure of CNN and summarizes the application of CNN in the field of mechanical faults from the aspects of input data type, network structure design, and migration learning. The problems of deep feature extraction and visualization are also discussed, and finally, the difficulties in mechanical fault diagnosis are analyzed and several problems to be solved in the field of mechanical fault diagnosis based on CNN prospect.
Research on Single-phase Grounding Line Selection Method for Distribution Network Containing New Energy
Authors: Liu Shen , Wang Shudong , Ma Chunlian , Wang Hao , Li Runqing
Published: January 2021

With energy shortages and environmental pollution problems becoming more and more serious, new energy electric energy has been rapidly developed and applied in the power system. Since most new energy electric energy needs to be connected to the power distribution system through an inverter device, this type of new energy electric energy is called an inverter-type distributed power source. With the access of distributed power sources, the power distribution system has changed from a single power source to a multi-power source system, and the system structure has changed. This brings great challenges to relay protection and fault line selection in the distribution network. Therefore, this article discusses the problem of single-phase grounding fault line selection in distribution network with inverter-type distributed power generation.
Study on the coupling effect of laser and diamond tool
Authors: Mingqiang Xia , Guangfeng SHI , Jiaolong BI , Jiyu GAO , Dawei YU , Guoquan SHI
Published: January 2021

In the process of turning hard and brittle materials with laser in-situ assisted diamond tools, the energy of the laser beam will be lost and the laser heat absorbed by the diamond tools will produce temperature fields and thermal deformations, which will affect the machining accuracy. In order to study the interaction between laser and diamond tool during laser in-situ assisted turning, a finite element model of laser and diamond tool transmission was established using COMSOL Multipysics, and the energy deposition formed on the rake face under different incident conditions was analyzed. The temperature field changes and the rule of tool tip deformation of diamond tools during laser irradiation are shown. Studies have shown that the greater the negative rake angle of the tool, the greater the power density deposited by the laser on the rake face. When the incident angle of the laser is 20°, the power density of the laser on the rake surface reaches the maximum. Under the laser irradiation, the temperature and the deformation of the tool tip increase with time, and finally reach a steady state. The research provides theoretical basis for improving the precision of laser in-situ assisted diamond processing.
Design and Implementation of Polarity Testing System of Contact-less Solenoid Valve Based on Wireless Sensor Networks
Authors: Li Yue , Zhang Xiaodong , Zhang Teng
Published: January 2021

Solenoid valves are important control components in industrial production and are used in various aerospace vehicles. In view of the characteristics and requirements of the solenoid valve polarity test of the launch vehicle power system, combined with some current research on magnetic flux leakage detection, and considering the difficulty of operation, a design scheme of a contact-less solenoid valve polarity test system based on Wireless Sensor Networks (WSN) is proposed. The solenoid valve of the launch vehicle was tested and verified. The system organically combines wireless sensor network technology, leakage magnetic field measurement technology, and rapid monitoring and interpretation technology. It has the characteristics of miniaturization, portability and cable-free. The software interface of the test instrument is more concise and beautiful, and it is accurate to the solenoid valve polarity system. Degree, portability, test coverage and user experience have all been significantly improved, which has important reference significance for the application of subsequent wireless test technology in other space vehicle tests.
Design and mechanical behavior analysis of clamping device of carbon fiber sucker rod working vehicle
Authors: Yan Wenhui , Xie Dong , Li Jie , Yuan Hengtong , Peng Yong
Published: January 2021

This paper optimizes the design of the clamping device of the carbon fiber sucker rod operating vehicle, aiming to improve the shearing problem when the carbon fiber sucker rod enters the clamping device. The structure of the clamping device is designed; Finite element software was used to simulate the state of the clamping device during actual work, the maximum displacement position of the carbon fiber sucker rod and the stress change curve of the sucker rod in the clamping device are obtained; Reasonably adjust the load distribution of the hydraulic cylinder according to the stress change curve of the sucker rod in the clamping device, so that the sucker rod in the clamping device bears a reasonable stress change, which is beneficial to reduce the shear of the sucker rod just entering the clamping device effect. The analysis shows that in the clamping device, the stress of the sucker rod is the largest when it just enters the clamping device. The load of the three hydraulic cylinders of the moving rail gradually increases from bottom to top, which can make the sucker rod bear the force uniformly and can improve the shear problem when the sucker rod just enters the guide rail.
Optimization of Aircraft Part No-Return Manufacturing Process Based on Value Stream Analysis
Authors: Haijun Yin , Yingji Shan
Published: January 2021

To target aircraft part manufacturing processes, this article analyzes the shortcomings of aircraft part “return” manufacturing process, and proposes the improvement solution of “no-return” manufacturing process optimization. By adopting measures, such as to cancel “returned” part hand-over, add work assignment to heat/surface treatment shop, add production schedule control by heat/surface treatment shop and improve part identification, etc., part fabrication cycle is reduced and part quality is improved. Based on the analysis and verification of value stream mapping before and after the improvement, the target of process optimization and restructuring is achieved.
Dispersion of Graphene Oxide in Saturated Ca(OH)2 Solution by Using Different Water-reducing Agents
Authors: Wang Yanan , Li Xiangyu , Chen Ya , Liu Zhuopeng
Published: January 2021

As a two-dimensional nano-material, graphene oxide (GO) has been found to be promising on improving properties of cement based materials. However, GO is prone to be agglomerated in the cement matrix. In this study, three different water reducing agents, including two polycarboxylate-based superplasticizers (PC1, PC2) and calcium lignosulfonate (CS), were used to study their effects on dispersion of GO in saturated Ca(OH)2 solution by conducting UV-vis analysis. The results showed the dispersion of GO can be largely improved when the mass ratio between PC1, PC2, CS and GO was 4:1, 4:1, 6:1, respectively. The UV absorptions increased with increase of the ultrasonication duration. When the ultrasonication was 10 minutes, CS showed better performance on the dispersion of GO. The dispersion of GO modified with PC1 can be improved by increasing the ultrasonication amplitude; while the amplitude showed little effect on the dispersion of GO modified by PC2 and CS.
Design of Three-chamber Ball Mill
Authors: Shang Guangchao , Wu Changzhong , Guo Hengshuai , Wu Liang , Wang Guitao , Zhao Mingpeng
Published: January 2021

Ball mill is a kind of raw material processing machinery which plays the role of grinding. Its working principle is that the movement and force are transmitted to the barrel of ball mill through reducer, transmission shaft and hollow shaft by motor. Through the continuous turnover movement of the cylinder, the grinding medium inside the cylinder is driven to crush and grind the materials. So as to obtain the product with suitable particle size. According to the specifications and parameters of the ball mill, the general layout, grinding body, lining plate, partition device, support device, transmission part and feeding and discharging device of the ball mill are designed. In this paper, the design method of three chamber ball mill is introduced. Comchambered with the design of Φ 3.5 × 13m three-chamber ball mill, the design process of ball mill is described in detail.
Analysis on affecting factors of magnetorheological finishing
Authors: Hao Lanfang , Liu Zhongling , Li Shixu , Zhu Ruiyu , Zhu Xuli
Published: January 2021

A magnetorheological finishing experimental device was designed and fabricated to explore influencing factors during polishing process. The device consists of the subsystems of mechanical transmission, workpiece clamp, magnetorheological fluid circulation and magnetic excitation. Magnetorheological fluids of different carbonyl iron volume ratio were prepared to research the effects with different workpiece speeds, polishing wheel speeds during magnetorheological finishing. The material of the workpiece is K9 glass. Experiment results show that the material removal rate increases with the workpiece speed and the speed of the polishing wheel. The increasing of volume ratio of carbonyl iron can also increase the material removal rate when the volume ratio is low, but the removal rate decreases when the volume ratio of the carbonyl iron powder reaches high value.
Analysis of single phase ground fault characteristics of low resistance ground active distribution network
Authors: Wu Na , Liu Zihui , Fan Shuxian , Dong Longjing , Yang Zhengxian , Zhou Chengxiang
Published: January 2021

A large number of distributed generators access to low resistance grounding system may have great influence on the fault characteristics of single phase ground. In view of low resistance ground active distribution network, the connection mode of Inverter-interfaced Distributed Generators (IIDG) is discussed comprehensively based on operation safety and protection requirements. The equivalent model of IIDG and simplified zero sequence network model of low resistance grounding system contain multi-IIDG for single phase ground fault are established. The amplitude and phase characteristics of zero sequence current in single phase grounding fault of the system and the characteristics of high-resistance ground fault are analyzed. Simulative results by MATLAB/Simulink verifies the correctness of the analysis results of fault characteristics. The conclusions could be provided as reference for solving the grounding protection of system with high penetration of distributed generator.
Fatigue analysis of airfoil under different working conditions
Authors: Xu Y , Zhang Y , Sun M
Published: January 2021

Within the flight mission envelope, the wing receives different aerodynamic loads in each mission stage, which results in bending and torsion alternating stress, which is prone to deformation or fatigue damage, threatening flight safety. Therefore, it is necessary to predict the fatigue life of the wing structure and maintain it in time to avoid accidents. Fluent software is used to analyze the aerodynamic load state of the wing when the lift-to-drag ratio is the largest under the three conditions of the climb, level flight, and landing, as the loading load of the wing, analyze the stress and strain of the dangerous points at each stage based on the finite element analysis platform, and determine Multiaxial fatigue state. The Brown-Miller multiaxial fatigue analysis method based on the critical surface was adopted, and the fatigue life analysis was carried out using the Fe-safe software and the Abaqus software. The results show that the minimum lifespan first appears at the root of the wing. In the Fe-safe analysis, the design life of the given wing structure is 40000 cycles, and the minimum life of the wing structure is calculated to be 58420 cycles, longer than the design life, and the life safety factor is 1.078, basically in line with the actual situation.
Research on security attack technology and detection method of RFID tag chip in intelligent electric meter
Authors: Wang Rui , Gong Qiujing , Zhen Ke , Hou Xing Zhe , He Min , Wang Ling Yu
Published: January 2021

This paper introduces the security threats faced by RFID chips of intelligent electric meters firstly, and then focuses on the attack principle and security detection methods of Side-Channel Attack, which are elaborated from four aspects: non-contact RFID card test, fault-injection test, software and hardware cooperative detection and physical detection.
An Air-Water Integrated Auxiliary Navigation System for Complex Waters
Authors: Shuang Xuecheng , Zhang Yan
Published: January 2021

The auxiliary navigation device described in this paper can effectively make up for the shortcomings of the existing navigation mode. It has designed a targeted detection module for various unstable factors in complex waters, such as large ship flow, frequent water level changes, low visibility, hidden reefs and floating ice. With the advantages of both water and air, excellent navigation performance and all-round detection means on water and underwater, the device can achieve excellent auxiliary pilot effect. In addition, the device has the advantages of low operation difficulty, short training period, high safety, good social and economic benefits, which is suitable for wide range promotion in navigation areas such as ports, inland rivers and coastal areas.
Network Security Risk Assessment of CPS System in Distribution Network Based on Attack Graph
Authors: Gangjun GONG , Peng ZHANG , Bo ZHOU , Ren QIANG , Yue SUN , Leran CHEN , Wei CHEN
Published: January 2021

With the development of advanced information and communication technology and intelligent control technology, the modern distribution network has gradually developed into a cyber-physical system of the distribution network, which also brings about the impact of information-side network security threats on the coupling failure of the physical-side power grid. In this context, a method for quantitative assessment of the network security risk of the distribution network CPS system suitable for the principle of power security protection is proposed. First of all, the physical architecture model of a typical distribution network information physical system was built; Secondly, for system network attacks, the attack path data stream related to device vulnerabilities is established, the attack behavior process is modeled based on the attack graph, and the series-parallel model is combined to calculate the success probability of attacking the target circuit breaker; Finally, the article takes the loss of load caused by the action of the attack circuit breaker as the physical consequence to quantify the risk value of the system and complete the network security risk assessment of the system.
First Order Sensitivity Calculation of Car Door Based on Combined Approximate Reanalysis Method
Authors: Feng Rui , Jin Yuchen , Yang Xiaochen , Guo Guikai
Published: January 2021

The reanalytic calculation method is a highly efficient method of reanalysing the modified structural performance, and initial structural information are used in the structural design process (optimization and modification). This method can avoid the complete analysis of the modified structure and significantly reduce the computational cost. In order to improve the efficiency of iterative calculation in the reanalysis of the door structure, this paper takes a car door as an example, and compares the sensitivity analysis with the combination of the approximate reanalysis algorithm and the current mainstream commercial software, and the calculation accuracy of the reanalysis method in this paper is verified by calculation examples.
Analysis of the Cause of Leakage Oil Defect in a Voltage-Dividing Capacitor of a 500kV Porcelain Circuit Breaker
Authors: Yang Xuefei , Li Hongkun , Wu Chunhong
Published: January 2021

In recent years, with the development and construction of the power grid system, the porcelain column circuit breaker has been popularized and applied in the 500kV substation. However, in the actual operation and maintenance process, the leakage of oil has been found in the grading capacitor. The disassemble of an oil leakage grading capacitor of a 500kV porcelain column circuit breaker is analyzed in this paper. Through carrying out the sealing test; the insulation performance test; salt spray test and simulation test. At the same time, by comparing the sealing ring and cover plate material; calculating the potential difference of the cover plate and researching electrochemical corrosion factors. We can come to an conclusion that the cause of a suspected the grading capacitor oil leakage is the oil accumulation; and the main reason for the oil leakage problem of the grading capacitor is the electrochemical corrosion phenomenon on the sealing cover plate. Finally, on the basis of the reasons, the relevant rectification measures are put forward.
Study on Corrosion Behavior of as-forged AZ81 Mg alloy in different concentrations of NaCl solution
Authors: Cao Fenghong , Qin Zhaohui , Xu Yaohui , Chen Chang
Published: January 2021

In this paper, the microstructure of as-forged AZ81 Mg alloy before and after heat treatment was analyzed by means of optical microscope and XRD, the corrosion behavior of as-forged AZ81 Mg alloy after heat treatment with different concentrations of NaCl solution was studied by static immersion weight loss method. The results show that: after solution aging heat treatment at 400°C×0.5h+200°C×20h, the grain size of the alloy is more uniform, but the effect on the average grain size is not obvious; when the corrosion time is fixed, the corrosion rate of as-forged AZ81 Mg alloy increases rapidly with the increase of NaCl concentration; with the extension of corrosion time, the corrosion rate of as-forged AZ81 magnesium alloy increases in a fluctuating manner, and then in a fluctuating decreases after reaching the peak value, and after 72h of etching, the corrosion rate of the alloy is basically unchanged; meanwhile, the corrosion in as-forged AZ81 magnesium alloy shows obvious filamentous propagation characteristics, and these filamentous corrosion characteristics basically extend and distribute along the grain boundary.
The forming tool, primary start position and toolpath angle movement effect on the geometry accuracy “springback”, part C
Authors: Abass K I
Published: January 2021

Incremental Forming process, IF is a technology for producing 3D-dimensional complex sheet profiles. The advantages of the process involve simple set tools, fixture and forming tool, shorter time for producing the pattern, and flexibility. While the main limitation of the process is the springback that represent geometry accuracy, the part profile precision limits the difficulty of forming toolpaths, including the wall angle. This work presents the forming toolpaths effect in the IF process. The supporting space and the product base dimension including wall angle is used to study the springback effect through the incremental forming process. Sheet metals Aluminium-A1025 are used for manufacturing the products. The research goals are to comprehend the springback defect behaviour which is affected by the supporting space-toolpath angle and the supporting space-product base ratios. The strain distributions and the thinning percentage of the final product section have been considered and analyzed in detail.
The modelling of detached chip area at square shafts machining with rack tools
Authors: Bordeanu M , Frumuşanu G , Oancea N
Published: January 2021

The paper deals with analyzing, by 3D modeling, the shape and the area of the chips detached during the machining of shafts with square cross section, by slotting with a rack tool. The proposed modeling requires at first to determine the tool profile. This step is accomplished by finding the equations of the surfaces family described by the tool relative to workpiece, and by using the enwrapping condition, written according to Minimum distance theorem. The generating process is modeled then, on the base of CATIA environment facilities, aiming to find, in graphical manner, the variation law of the detached chip. Solving this problem could be a primary level of analysis needed for designing the hobbing tool used for machining the same type of part. A numerical and graphical application of the proposed modeling algorithm is also included. The final goal of the research is to deliver the necessary information for smoothing the addressed machining process by modifying the kinematics of the generating process.
Estimating the warranty returns and proving root causes using statistical analysis of archived parameters measurements for an automotive mechatronic device
Authors: Braga I C , Udroiu R , Nedelcu A
Published: January 2021

In the mass production of the automotive industry, there are many cases in which a problem is not detected in the production processes of the supplier, but after delivery, in the customer’s assembly line. As a result, it is necessary to know both root causes to prevent them, but especially, if it cannot be detected even in the customer’s processes, to estimate the probability of occurrence in the warranty period. The paper’s aim is to present the analysis of the measurements of the mechatronic devices indirect parameters linked with the effect of the failure and by statistical correlation to prove the root causes. A study case will be used to understand the failure first occurrence and the duration of its effect, as the symptom description as well, in that way it will support the estimation of the warranty return number of parts, eventually, the accounting department can establish the provisions based on the output data.
Study upon the kinematic simulation of the incremental forming carried-on using a serial industrial robot
Authors: Breaz R E , Racz S G , Girjob C E , Tera M
Published: January 2021

Incremental forming with contact between tool-sheet metal workpiece in a single point is an unconventional process which allow the user to manufacture parts by combining the vertical movement of the tool along Z-axis and the horizontal movements of sheet metal workpiece, which are performed in XY plane. As technological equipment able to control coordinated movements on three axes, CNC machining centers and industrial serial robots with six degrees of freedom are the most suitable. The paper introduces a study regarding the use of robots as technological equipment for the process, by means of simulation. Supplementary degrees of freedom and singularities avoidance are also considered.
The optimization of cutting parameters at turning, using electrical current at cutting, in order to increase the durability of the cutting tool
Authors: Daicu R , Diţu V
Published: January 2021

The optimization of the turning cutting parameters was a permanent concern for research but also for production. The emergence of new metal materials to be processed as well as the development of new cutting edges has always led to new optimizations of the cutting regime. The appearance of coated plates, single layer or multilayer, determined the companies producing them to indicate information about the cutting parameters, but the values are given in a certain interval. In order to reduce the necessary experiments to indicate the optimal cutting regime, the paper proposes the analysis of the electrical current at cutting and its use for optimization. The processing of the experimental data obtained as well as the optimization of the cutting parameters was performed using Design Expert software.
Simulation research on pressure shock of load sensing system of large boom tower crane
Authors: Fei Y , Li J , Sun C
Published: January 2021

Large boom tower cranes have large masses, heavy loads, and large inertial dynamic loads during the conversion of working conditions. Even if there is a buffer device, hydraulic shock will still occur. The problem of hydraulic shock seriously affects the leakage of hydraulic oil and decreases system reliability. Now the closed hydraulic system of a certain type of boom tower crane is taken as the research object, and the joint modeling of machinery and hydraulic is completed in AMESim. Without changing the basic hydraulic components, the hydraulic system of the whole machine just adjusts the ratio of the pulley block or changes the hydraulic speed regulation method to study the hydraulic shock of the servo-sensitive hydraulic system. AMESim simulation results show that in this load-sensitive system, the double-rate hoisting of the pulley block is compared with the single-rate hoisting of the pulley block, the maximum dynamic load generated by the load off the ground is increased by 5.4%; Speed regulation of the variable pump and variable motor combination is compared with the speed control of only variable motor, the maximum dynamic load of the hydraulic system is reduced by 7.6%.
Analysis of the influence on the hydraulic lifting circuit of the boom crane when the characteristics of the steel wire rope changes
Authors: Fei Y , Jiang J , Sun C
Published: January 2021

In the process of lifting and landing of large hydraulic crane fully loaded, the working condition conversion makes the stress of steel wire rope change frequently and generate additional dynamic load, which makes the movement of the crane unstable and affects the working stability of the hydraulic system, and also leads to the fatigue damage of the tower structure and reduces the effective working life of the tower crane. In order to find the optimal dynamic characteristics of hydraulic system, the initial tension force, stiffness of hoisting wire rope and rigidity of variable amplitude wire rope of hoisting wire rope are studied respectively by means of machine-liquid integration simulation based on the AMESim, a kind of simulation software. The lifting mechanism of a type of closed hydraulic system is modelled and simulated. The results show that the maximum dynamic load of hoisting mechanism is reduced by 92.6% and the stabilization time is reduced by 49%. The optimized stiffness of hoisting wire rope reduces the dynamic load and peak pressure of hoisting mechanism by 5.2% and 4.3% respectively. The stiffness of the variable amplitude steel wire rope has little effect on the dynamic characteristics of lifting.
Application of fractal theory in fault diagnosis of nonlinear mechanical equipment system: a review
Authors: Hou X L , Wang X
Published: January 2021

Fractal theory takes the irregular and complex things as the research object, and uses the fractal dimension to describe the object. The review classifies and summarizes the application development of fractal theory in the diagnosis of common nonlinear mechanical equipment system faults such as diesel engines, gear boxes, hydraulic systems, etc. It is showed that fractal theory can extract and analyse irregular features and simplify complex research. It has certain advantages among various methods and is gradually being widely used. It provides a new reference and idea for the future research direction after fully understanding its current status and summarizing its characteristics. At present, most of the research on fault diagnosis of mechanical equipment is based on the signals under steady running state, while ignoring the transitional signals with high information content. Fractal theory has unique advantages in dealing with this kind of transitional signals such as the start and shutdown of equipment. It is a new trend to solve practical problems that study the short-time signals at transition process with strong non-linearity based on fractal theory to diagnose the fault of the mechanical equipment.
Voice frequency impact for voice control of collaborative robots
Authors: Janíček M , Holubek R , Ružarovský R , Velíšek K
Published: January 2021

The project is focused on research of voice control of collaborative robots. Previous research of voice control and speech recognition research have given examples and evidence that machines can truly be controlled by human voice. The main problem in the voice control of collaborative robots is the lack of reliability and safety of control compared to manual control. Of the results achieved, the most and least relevant voice control problem has been clearly identified, next step is voice frequency impact for voice control. The experiments were performed in the robotics laboratory at the Faculty of Materials Science and Technology in Trnava, and this using an Arduino kit and a small robot “DOBOT Magician“. In the final part of the project are summarized all experimentally found facts and confronted with the assumptions set in the design of the experiment.
Study of milling machining roughness prediction based on cutting force
Authors: Kao Y C , Chen S J , Vi T K , Feng G H , Tsai S Y
Published: January 2021

Cutting parameters can to be properly adjusted to increase machining precision, to enhance cutting efficiency, and to reduce cost. These parameters are generally chosen according to the recommended data from the tool maker’s technical manual with the synergy of the operator’s experiences. However, inappropriate parameters selection might not only damage cutter and the machine tool, but also worsen the surface roughness of the workpiece. Researches on improving surface roughness has been studied over the years, for example, on the optimization of cutting conditions, vibration measurement and analysis, and cutting forces measurement and analysis, to name only a few. However, most of them must have sensors installed on the machine tool for data collection before the analysis. This will increase the cost. Furthermore, the measurement of cutting force needs to have dynamometer which is not only expensive but is also not appropriate to be installed on a small-sized machine tool. This research focused on establishing the relationship between the cutting force and the surface roughness for the workpiece machining in a small-sized machine tool. In order to calculate the cutting force, cutting force coefficients were obtained based on the cutting test on the other machine tool rather than the small-sized machine. Tapping test was also conducted to obtain the frequency response function of the machine. The cutting forces were calculated based on the cutting force coefficients and the frequency response function. The calculated cutting forces were then converted through the proposed methodologies into eleven characteristic values. Finally, two commonly used machine learning algorithms, multivariate linear regression and generalized regression neural network were adopted for regression analysis to establish the relationship between the cutting forces and the surface roughness. The results have shown that the prediction by generalized regression neural network is better than that of multivariate linear regression. The major contribution of this paper is that appropriate algorithms have been studied, compared and verified so that the relationship between cutting force and surface roughness can be established. This means that surface roughness can be estimated based on the calculated cutting forces incorporating the machine tool’s frequency response function.
Prediction of radial clearance based on bearing vibration using artificial neural network
Authors: Knežević I , Živković A , Rackov M , Kanović Ž , Buljević A , Bojanić Šejat M , Navalušić S
Published: January 2021

Artificial neural networks are used for diagnosing of ball bearings condition. They are capable to recognize bearing fault from information extracted from signal of vibration. The aim of the work is to investigate the relationship between vibration velocity in the characteristic band frequencies and radial clearance. Changing the radial clearance during operation may indicate changes in the operation of the rotating system. Experimental research is based on deep groove ball bearings and measuring the vibration of the bearings. The vibration velocities for each bearing were measured under laboratory conditions, and the processed signals were used to train the artificial neural network. An artificial neural network trained in this way can predict the size of the radial clearance based on the vibration of the bearing.
Fabrication and service of all-ceramic ball bearings for extreme conditions applications
Authors: Li S , Wei C , Wang Y
Published: January 2021

Hot isostatic pressing silicon nitride material has properties that most metal materials do not have, such as low specific gravity, high strength, high stiffness, wear resistance, corrosion resistance, extreme temperature resistance, electrical insulation, no magnetic permeability, and excellent dimensional stability Performance, self-lubricating performance, etc. It is one of the ideal alternative materials for the manufacturing of bearings applied to various extreme conditions. This manuscript focuses on the practical needs of bearings for environmental equipment such as extreme temperature and marine corrosion. These bearings are used to improve the ultimate speed and load capacity of the whole steel bearing design system in ultra-high speed applications (such as machine tool spindle and gas turbine engine); to eliminate corrosion and reduce friction under extreme temperature or corrosion conditions, so as to improve system performance. In this paper, from the preparation of ceramic bearing materials to the ultra-precision machining process of ceramic bearing components, the development status of ceramic bearings in recent years is introduced, and the future development and application prospect of ceramic bearings are prospected.
A brief review of numerical simulation in process machining
Authors: Malea C I , Nitu E L , Iordache M D
Published: January 2021

Machining is a technological process that involves removing the material by generating chips, aiming to obtain flat, cylindrical, helical surfaces etc. This processing method is widespread in the industry and it is, therefore, necessary to define appropriate technical and economic solutions concerning the materials and geometry of the tools, the orientation and fixture of the devices, and the machine-tool used. It is also particularly important to use the most appropriate cutting parameters for modern industrial applications. Scientific research addresses these issues through analytical, semi-empirical, or numerical modeling. Numerical modeling and simulations can satisfy with very good precision the solutions of these aspects, with diverse methods and techniques used in the study of the cutting simulation. This paper presents an analysis of recent studies, briefly presenting the main approaches and techniques used in numerical modeling and simulation of machining. The input parameters, components, and output parameters of these numerical models are identified as well. Finally, the advantages and disadvantages of using these methods and techniques are summarized, as well as the problems to be developed in the area of numerical modeling and simulation of cutting processes.