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    Industrial Engineering and Lean Management for Smart Manufacturing
    QI Ershi, HUO Yanfang, LIU Hongwei
    China Mechanical Engineering    2022, 33 (21): 2521-2530.   DOI: 10.3969/j.issn.1004-132X.2022.21.001
    Abstract988)      PDF (4622KB)(671)       Save
    This paper reviewed the development routes of developed countries such as the United States, Japan, and Germany since the emergence of industrial engineering for more than 100 years, discussed the regular characteristics of enterprise management innovation, and drew the conclusion that smart manufacturing also needed IE/LM to provide management support. According to the smart manufacturing project cycle, the functions of IE/LM in smart manufacturing engineering were analyzed from the perspectives of basic preparation, scheme selection, and integration development. The framework of lean smart management system for smart manufacturing transformation of Chinese enterprises was given, and the improvement ideas and methods of smart-lean integration were explained based on a case. Finally, some key technologies of smart manufacturing management facing transformation and upgrading of Chinese enterprises were presented based on the actual needs of China. 
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    Development Status and Prospect of Key Rail Grinding Equipment and Technology of Grinding Stone
    ZHANG Wulin, FANXiaoqiang, ZHU Minhao, DUAN Haitao
    China Mechanical Engineering    2022, 33 (19): 2269-2287.   DOI: 10.3969/j.issn.1004-132X.2022.19.001
    Abstract581)      PDF (17216KB)(605)       Save
     The rail grinding strategies and techniques were reviewed, and the key equipment of the grinding methods using grinding wheels(active grinding and high-speed passive grinding)and the milling and grinding compound process were summarized. Meanwhile, the research status of rail grinding stone(grinding wheel, equipped with rail grinding train and used for cutting tools)were reviewed from ingredients, forming processes, structural design and grinding performance evaluation criterions, etc. It was concluded that the fine formula design, scientific evaluation criterions, etc. were the main challenges for the development of high-performance grinding stones. Finally, it was pointed out that the greenization, standardization, and intelligence were the important directions for future development of grinding stone technology. 
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    Rebound Law and Precision Compensation Method of Three-dimensional Laser Cutting of High Strength Steel Hot Stamping Structural Parts
    LI Shougang, LIU Peng, LIU Xiang, HU Zhili,
    China Mechanical Engineering    2022, 33 (22): 2741-2747.   DOI: 10.3969/j.issn.1004-132X.2022.22.012
    Abstract420)      PDF (7408KB)(54)       Save
    In order to reduce the influences of springback defects on the cutting accuracy in the three-dimensional laser cutting of high-strength steel body structures, the rebound characteristics was studied by applying three-dimensional laser cutting of hot stamped high-strength steel body components.For high-strength steel car body structure A-pillar, hot stamping and laser cutting finite element models were established respectively by the finite element simulation software AUTOFORM and ABAQUS respectively. The rebound value distribution diagram was obtained through numerical simulation, and the rebound law of the contour of the body structures after cutting was found. The optimal cutting contour was determined according to the direct compensation method based on rebound prediction. The compensation method was validated by cutting the A-pillar semi-finished products. The results show that the contour may be controlled within the tolerance range, the contour errors are decreased by about 28.5%, and the profile rebound is decreased by about 38.3%,by the proposed compensation method,which verify the effectiveness of the compensation method.
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    Review on Management at Mechanical Design and Manufacturing Discipline of NSFC in 2022
    YE Xin, ZHU Mingliang, HUANG Zhiquan,
    China Mechanical Engineering    2023, 34 (04): 379-386.   DOI: 10.3969/j.issn.1004-132X.2023.04.001
    Abstract389)      PDF (2658KB)(206)       Save
    The applications, evaluations and funding of projects at mechanical design and manufacturing discipline (division Ⅱ of engineering science) of the NSFC in 2022, as well as the research progresses and achievements of the executing and finished projects were reviewed. Specific measures of mechanical design and manufacturing discipline were illustrated, such as the reform of scientific fund, talent cultivation and future research. Finally, a short prospect of the work in 2023 was introduced. 
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    Modeling of Material Removal Depth in ABFW Polishing Based on Modified Preston Equation
    ZHANG Junfeng, SHI Yaoyao, LIN Xiaojun, WU Xiaojun
    China Mechanical Engineering    2022, 33 (22): 2711-2716.   DOI: 10.3969/j.issn.1004-132X.2022.22.008
    Abstract368)      PDF (4289KB)(111)       Save
    Due to the elasticity of ABFW, the actual material removal depth was not consistent with the nominal polishing depth, which directly affected the control of polishing efficiency and surface quality. Based on the Hertz elastic contact theory, the distribution function of polishing pressure and cutting speed in the contact area was established, and the material removal depth model was established according to the modified Preston equation. Based on this, the key processing parameters that affected the material removal depthi.e、abrasive particle size, spindle speed, ABFW deformation and feed rate were determined. Then, the distribution of material removal depth in contact areas and the influences of key polishing process parameters on the material removal depth were obtained. Finally, the correctness of the model and the influence law were verified by simulation and polishing experiments, the results show that the model may better predict the material removal depth of ABFW polishing. 
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    Research on Accelerated Life Test Method of Harmonic Reducers
    WANG Qiao, DU Xuesong, SONG Chaosheng, ZHU Caichao, SUN Jianquan, LIAO Delin
    China Mechanical Engineering    2022, 33 (19): 2317-2324.   DOI: 10.3969/j.issn.1004-132X.2022.19.005
    Abstract360)      PDF (5879KB)(182)       Save
    At present, there was an urgent need for an accelerated life test method of harmonic reducer in engineering to replace the full life test in order to reduce the test cycles and costs. Based on the principles of accelerated life test, a constant stress accelerated life test program  was proposed based on the failure characteristics of the harmonic reducer. The flexible wheel that was most likely to fail in the harmonic reducers was taken as the object, and the definite failure judgment, acceleration stress, acceleration factor, method of accelerating model were pointed out. In the small sample test data processing, a more accurate Weibull distribution parameter estimation was obtained by using the maximum likelihood method and Markov Monte Carlo method. The experimental results of the prototype show that the scheme may effectively describe the life of the harmonic reducers. The reliability evaluation standard of the basic rated life is 62% higher than that of the evaluation standard of the median life. The life index of the harmonic reducers was effectively evaluated. The research results have certain engineering application values. 
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    Research Review of Error Compensation Technology for Ultra-precision Machining
    CHEN Qidi, HU Xiaolong, LIN Min, SUN Xiaoxia, ZHANG Tao, ZHOU Zhixiong
    China Mechanical Engineering    2023, 34 (03): 253-268.   DOI: 10.3969/j.issn.1004-132X.2023.03.001
    Abstract336)      PDF (8557KB)(245)       Save
     Ultra-precision machining technology was a key technology in high-end manufacturing fields. At present, ultra-precision machining has entered the nano scale. Mastering the key technology of ultra-precision machining error control, ensuring and improving the machining accuracy of CNC machine tools, become a hot research point to improve the machining and manufacturing levels. This paper systematically summarized the research status and development trend of ultra-precision machining error compensation technology, and focused on the geometric errors, force induced errors, thermal induced errors and their compensation methods, which had the greatest impact on ultra-precision machining. Then, a series of problems of ultra-precision machining in geometric error separation, cutting force, thermal induced error measurement and compensation were deeply discussed, and it is further pointed out that the ultra-precision machining error compensation technology should also pay attention to the development direction of high efficiency, high precision, generalization, modularization, intelligence and flexibility.
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    Metal Defect Image Recognition Method Based on Shallow CNN Fusion Transformer
    TANG Donglin, YANG Zhou, CHENG Heng, LIU Mingxuan, ZHOU Li, DING Chao
    China Mechanical Engineering    2022, 33 (19): 2298-2305,2316.   DOI: 10.3969/j.issn.1004-132X.2022.19.003
    Abstract328)      PDF (8847KB)(196)       Save
    Aiming at the problems of large amount of parameters and calculation in the field of metal defect recognition, a metal defect recognition method was proposed based on shallow CNN and Transformer model. The shallow CNN was used to learn the local information and position information of the images, and the Transformer was used to learn the global information of the images. At the same time, the channel attention module SE was introduced to pay attention to the important feature channels to realize the defect image recognition. The effectiveness of this method was verified by introducing the open defect data set, and the universality of this method was verified by using the self-built defect ultrasonic data set. The experimental results show that the proposed method has strong universality and may effectively identify metal defect images on small and medium-sized data sets. 
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    Construction Method of Virtual-real Drive Systems for Robots in Digital Twin Workshops
    LIU Huailan, ZHAO Wenjie, LI Shizhuang, YUE Peng, MA Baorui
    China Mechanical Engineering    2022, 33 (21): 2623-2632.   DOI: 10.3969/j.issn.1004-132X.2022.21.011
    Abstract319)      PDF (2935KB)(252)       Save
     For the current problems for complex modeling and long development cycle of virtual entities such as industrial robots in digital twin workshop construction, a modular construction method of virtual-real drive systems for industrial robots in digital twin workshops was proposed, which divided the virtual-real drive systems into an interaction layer for setting model parameters and a control layer for designing configurations according to functional requirements, and then abstracted the physical industrial robots, etc. into a simulation model from coupling single functional atomic model. The modular and hierarchical approach to building virtual-reality drive systems may quickly and effectively realize the modeling of digital twin virtual entities such as industrial robots, as well as the simulation of industrial robots operating in virtual space and the simultaneous operation of virtual-reality.
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    Tooth Surface Generation and Meshing Characteristics Analysis of Low-angle Face Gear Drives
    ZHOU Ruchuan, WU Wenmin, FENG Manman, GUO Hui, LIN Yanhu
    China Mechanical Engineering    2023, 34 (06): 631-640.   DOI: 10.3969/j.issn.1004-132X.2023.06.001
    Abstract318)      PDF (6100KB)(207)       Save
     Gear geometry and meshing properties of the low-angle face gear drives were investigated in order to enhance meshing capabilities of the gear drives with small shaft angle in helicopter transmission systems. The applied coordinate systems for generation of the low-angle face gear drive were established and the equation of the tooth surface of the small cone angel face gear was derived based on gear meshing theory. The tooth surface equation of a double-crowned cylindrical involute pinion was deduced by application of a generating worm.  The generated double-crowned pinion was then introduced into the low-angle face gear drive. The TCA was implemented and the influences of misalignments on the contact were researched. Stress analysis was performed for the purpose of evaluating the performance of the proposed face gear drives. And the stresses of the low-angle face gear drive were compared with the conical involute gear and cylindrical involute gear pair. The results show that the application of double-crowned pinion avoids edge contact, providing lower contact and bending stresses compared with the face-gear drive with a longitudinal modification pinion. Under the same conditions, the contact and bending stresses of the tapered face gear are 27% decrease than that of the conical involute gears. 
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    A Collision Detection Method of Heavy-duty CNC Machine Tools Based on Digital Twin
    JIANG Xuemei, YUAN Zihang, LOU Ping, ZHANG Xiaomei, YAN Junwei, HU Jiwei,
    China Mechanical Engineering    2022, 33 (22): 2647-2654,2663.   DOI: 10.3969/j.issn.1004-132X.2022.22.001
    Abstract298)      PDF (10716KB)(173)       Save
    At present, the collision detection of CNCMTs usually used the basic simulation function of the CNC system to detect machining G codes, which only considered whether there were collisions between the tool and the ideal workbench, or the tool and fixtures on the tool path during the processes. It was difficult to meet the actual dynamic processing environments, clamping mode and fixture change of open heavy-duty machine tools. So the digital twin was introduced into the collision detection of open heavy-duty CNCMTs, and a perception-evolutionary prediction-feedback collision detection framework was constructed. By constructing digital twin of CNCMTs and dynamically sensing machining elements such as workpieces ,fixtures and cutting tools, the evolution of the digital twin should be driven by perception data, and the potential interference phenomenon would be predicted in the machining processes. Thus, the efficiency of the CNCMTs was improved, and the potential harm was avoided. The method was applied to the collision detection of heavy-duty CNC gantry boring and milling machine ZK5520, and the effectiveness and feasibility of the proposed method were proved.
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    Tribological Properties and Anti-friction Electrostatic Properties of CF/PEEK Composites
    PANG Xianjuan, YUE Shiwei, HUANG Suling, XIE Jinmeng, WANG Shuai, SONG Chenfei, YUE Yun, LIU Jian, LI Dong
    China Mechanical Engineering    2023, 34 (03): 277-286.   DOI: 10.3969/j.issn.1004-132X.2023.03.003
    Abstract291)      PDF (16300KB)(101)       Save
    CF/PEEK composites were prepared by vacuum hot pressing sintering technology. The thermal properties of the materials were tested by thermal conductivity analyzer and TG tester. Multifunctional friction and wear testing machine, 3D morphology profilometer, scanning electron microscope and friction electrometer were used to analyze the friction and wear properties and anti-friction electrostatic properties of the materials. The results show that with the increase of the forming temperature, the friction coefficient and wear rate of the materials decrease gradually. With the increase of CF contents, the friction coefficient, wear rate and friction electrostatic voltage decrease first and then increase. When the CF content is as 20%, the friction coefficient, wear rate and friction electrostatic voltage reach the lowest values, which are as 0.247, 5.6×10-6 mm/(N·m) and 3.3 V, respectively. Friction and electrostatic data show that the CF/PEEK materials prepared by this method have better friction properties and anti-electrostatic properties than that of commercial composites. The wear mechanism of CF/PEEK composites is mainly adhesive wear, accompanied by slight abrasive wear.
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    Scale Optimization of Humanoid Robotic Arms Based on Kinematic Performance Analysis
    SUN Peng, LI Yanbiao, ZHANG Cong, SHAN Xiaohang, YUE Yi, WEI Baochen
    China Mechanical Engineering    2022, 33 (19): 2331-2340.   DOI: 10.3969/j.issn.1004-132X.2022.19.007
    Abstract284)      PDF (10626KB)(327)       Save
     Aiming at the problems that the coupling effect of multi-joint series mechanisms on the kinematic performance of the end-effector, the kinematic characteristics of series-parallel hybrid mechanisms were analyzed, and a multi-parameter plane model was proposed to realize visualized design. Based on screw theory, the kinematics transfer matrices of serial and parallel joints were established respectively, and the corresponding performance indexes were set up. According to the multi-parameter plane model, the coupling relationship among parameter scale, orientation workspace, and performance indexes were further revealed through a three-dimensional visualization graphics. Finally, the values of parameters, the range of high-quality orientation workspace, and the distribution of indexes were confirmed. The results show that the global performance indexes of the shoulder and wrist joints are as 0.78 and 0.67, respectively, and the global condition number of the elbow joint is as 2.38. The hybrid configuration has functions similar to that of the human arm joints, and gives full play to the comprehensive advantages of series and parallel mechanisms. 
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    Study on Leakage Characteristics and Dynamic Characteristics of New Type of Vortex Groove Seals
    JIANG Jinyu, SUN Dan, ZHAO Huan, ZHANG Guochen, LI Yu, WEN Shuaifang
    China Mechanical Engineering    2022, 33 (19): 2306-2316.   DOI: 10.3969/j.issn.1004-132X.2022.19.004
    Abstract283)      PDF (13329KB)(116)       Save
    A new seal structure with vortex groove in the circumferential direction of the sealing inlet was proposed. The theoretical models of traditional labyrinth seal and the new type of vortex groove seal leakage characteristics and dynamic characteristics were established. Based on the model accuracy verification by means of experiments, the leakage characteristics and dynamic characteristics of the traditional labyrinth seal and the new type of vortex groove seal  were compared and analyzed under different inlet/outlet pressure ratios and pre-whirl ratios. The influence mechanism of the new vertex groove structure on the seal leakage and dynamic characteristics was studied. The results show that with the increase of the number of vortex groove, the leakage of vortex groove  seal decreases gradually. Under the same pressure ratio, the difference between the leakage of the new seal with different number of vortex grooves increases with the increase of the pressure ratio. When the pressure ratio is as 6, compared with the traditional labyrinth seal, the leakage of the 64 vortex grooves seal is reduced by 3.37%. Under the conditions of high pre-whirl ratio, the tangential airflow force of the seal with different number of vortex grooves is opposite to the direction of rotor vortex, which plays a role in inhibiting rotor vortex, the tangential airflow force increases with the increase of the number of vortex grooves. With the increase of rotor vortex frequency, the cross stiffness of seals with three different number of vortex grooves first decreases to negative value and then increases to positive value. The effective damping of the vortex groove seals is higher than that of the traditional labyrinth seals. The new vortex groove seal may improve the stability of the rotor systems. 
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    Study on Crack Repair Performance of Si3N4/TiC/ZrSi2 Ceramic Tool Materials
    ZHANG Shuai, CHEN Zhaoqiang, XIAO Guangchun, YI Mingdong, ZHANG Jingjie, ZHOU Tingting, XU Chonghai
    China Mechanical Engineering    2022, 33 (19): 2288-2297.   DOI: 10.3969/j.issn.1004-132X.2022.19.002
    Abstract282)      PDF (14085KB)(195)       Save
    To solve the problems that ceramic tools were sensitive to cracks, ZrSi2 crack repairing agent was added into Si3N4/TiC ceramic tool material matrix, which made ceramic tools have crack repairing ability. When ZrSi2 content was as 10% (volumn fraction), Si3N4/TiC/ZrSi2 ceramic tool materials had better comprehensive properties, with flexural strength of 815 MPa, fracture toughness of 8.06 MPa·m1/2, Vickers hardness of 15.91 GPa and relative density of 99.72%. Cracks were introduced into the surface of ceramic tool materials by Vickers hardness tester, and the optimal repair parameters and repair mechanism of cracks in Si3N4/TiC-based ceramic materials with ZrSi2 as repair agent were studied. The research shows that the flexural strength of Si3N4/TiC/ZrSi2 prefabricated crack specimen with 10% ZrSi2 added may be restored to 92.02% of that of smooth specimen after heat treatment at 800 ℃ for 60 min in air atmosphere, and the crack with the surface length of 300~350 μm is completely repaired, and an oxide layer mainly composed of ZrO2 and SiO2 is formed on the surface of the specimen. The mechanism of crack repair of ceramic cutting tool materials is analyzed as follows:in the air heat treatment processes, ZrSi2, a healing agent at the crack and the surface of the material, preferentially reacts with oxygen to generate ZrO2 and SiO2, which heal the crack on the surface of the material and restore the strength of the crack sample. At the same time, during cutting, ZrO2 and SiO2, oxidation products of ZrSi2 at the cracks and material surfaces, may repair the crack in time and improve the wear resistance of the tool. 
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    Low-carbon Scheduling of Multi-objective Flexible Job-shop Based on Improved NSGA-Ⅱ
    JIANG Yixiao , JI Weixi, HE Xin, SU Xuan
    China Mechanical Engineering    2022, 33 (21): 2564-2577.   DOI: 10.3969/j.issn.1004-132X.2022.21.006
    Abstract282)      PDF (6637KB)(156)       Save
     To solve the low-carbon scheduling problems of multi-objective flexible job-shops taking equipment energy consumption, tool wear and cutting fluid consumption as carbon emission sources and energy consumption and labor cost as processing cost, a low-carbon scheduling model was formulated to minimize carbon emission, makespan and processing cost, and an improved elitist NSGA-Ⅱ was proposed to solve the problem. Firstly, the chromosome composition was dynamically adjusted by encoding based on Tent chaotic map and greedy decoding based on analytic hierarchy process to improve the quality of the initial population. Then, an adaptive genetic strategy was proposed based on genetic parameters, which adjusted the crossover and mutation rates according to the population evolution stage and the population non dominated state dynamically. Finally, based on external archives an improved elite retention strategy was designed to improve the population diversity in the later stages of the algorithm and retain high-quality individuals in the evolution processes. The effectiveness of the improved algorithm was verified by standard scheduling examples and a practical case. 
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    Research on Flexible Job-shop Scheduling Problems with Integrated Reinforcement Learning Algorithm
    ZHANG Kai, BI Li, JIAO Xiaogang
    China Mechanical Engineering    2023, 34 (02): 201-207.   DOI: 10.3969/j.issn.1004-132X.2023.02.010
    Abstract279)      PDF (4473KB)(220)       Save
    The flexible job-shop scheduling problems were transformed into a Markov decision process, and an algorithm D5QN integrated with 5 kinds of deep Q-network (DQN) optimizations was proposed. In the constructing of Markov process, a set of features was extracted to describe the states, and 3 sets of actions were designed by composite rules. The rewards were mapped by direct and indirect methods. The proposed algorithm was compared with the algorithms based on rules, meta-heuristic, and other reinforcement learning, which verifies the proposed algorithm may further decrease the calculating time, and have feasibility and effectiveness. 
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    Fault Diagnosis Method of Rolling Bearings Based on Simulation Data Drive and Domain Adaptation
    DONG Shaojiang, ZHU Peng, ZHU Sunke, LIU Lanhui, XING Bin, HU Xiaolin
    China Mechanical Engineering    2023, 34 (06): 694-702.   DOI: 10.3969/j.issn.1004-132X.2023.06.008
    Abstract270)      PDF (6394KB)(190)       Save
    To solve the problem that it was difficult to obtain a large number of high-quality rolling bearing fault data in the actual industrial environment, and the generalization performance of the intelligent diagnosis model was poor, a fault diagnosis method was proposed based on simulation data driven and domain adaptation. Firstly, a physical model was established to obtain rich simulation data, which simulated different failure forms of bearings according to bearing parameters and corresponding operating conditions. Secondly, the transfer learning method was used to solve the problem of inconsistent data feature distributions between simulation and actual fault data. The residual channel attention mechanism network was used to extract the transfer fault features of different domains, and the adaptive operation of different domains in the network training processes was carried out through the condition maximum mean discrepancy metric criterion, which taken into account the conditional distribution discrepancies between different domains. Finally, different transfer model tests were carried out on the bearing data sets damaged by man-made damage and accelerated life test. The results show that the method proposed may obtain better recognition accuracy when the target domain contains a small number of labels. 
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    Strength-constrainted Topology Optimization Based on Additive Manufacturing Anisotropy
    HE Zhicheng, YANG Dingding, JIANG Chao, WU Yi, JIANG Hexin
    China Mechanical Engineering    2022, 33 (19): 2372-2380,2393.   DOI: 10.3969/j.issn.1004-132X.2022.19.012
    Abstract269)      PDF (6452KB)(135)       Save
    The particularity of additive manufacturing processes leds to the fact that the manufacturing structure exhibited anisotropic mechanics properties. In order to meet the more stringent structural strength design requirements, atopology optimization strategy considering anisotropic strength constraints was proposed based on bi-directional evolutionary structural optimization. The anisotropic Tsai-Hill failure coefficient evaluating additive structural strength was derived, and an objective function containing the constraint of failure coefficient was established by the scale factor. The sensitivity numbers were analyzed in detail, moreover, numerical methods such as sensitivity normalization were used to stabilize the optimization processes. It shows that the proposed method effectively suppresses the high failure risk area, thus, ensures the structural strength, and may obtain better results than that of von-Mesis stress-dependent design under material anisotropic strength assumption. In addition, the optimization results are deeply rely on the variation of anisotropy and the material stacking angle parameters, therefore reasonable tuning will help to optimize structural properties. 
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    Vehicle High-precision Positioning Technique Based on Multi-sensors Information Fusion
    SHI Xiaobo, ZHAO Dingxuan, KONG Zhifei, NI Tao, ZHAO Xiaolong, GUO Qinghe
    China Mechanical Engineering    2022, 33 (19): 2381-2387.   DOI: 10.3969/j.issn.1004-132X.2022.19.013
    Abstract268)      PDF (3204KB)(164)       Save
     In order to solve the positioning error problems of multi-axle emergency rescue vehicles driving in complex environments, a combined positioning system was designed based on multi-information fusion. The positioning system was mainly composed of a front-end odometer and a back-end optimization model. The three-axis vehicle kinematics modeling was completed, the inertial measurement unit-based kinematics prediction equation and global positional system-based kinematics observation equation were derived, the state was updated through the Kalman filter, and the construction of the front-end odometer was completed. The external reference calibration tool was designed based on iterative closest point matching algorithm, and a feature point cloud matching model  was constructed to complete the back-end model optimization. Finally, after simulation and experiments were carried out, the results show that the positioning errors of the system are less than 3.45 cm, the angle errors are less than 0.10 degrees, the accuracy and stability are greatly improved. 
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    Topological Structure Synthesis and Optimization of 1T2R Parallel Mechanisms
    WANG Manxin, LI Lanbin, LI Zhengliang, LIU Haitao, HUANG Tian
    China Mechanical Engineering    2022, 33 (20): 2395-2402.   DOI: 10.3969/j.issn.1004-132X.2022.20.001
    Abstract266)      PDF (6266KB)(172)       Save
    The topological structure synthesis and optimization of 1T2R parallel mechanisms was studied herein. Applying the composition principles and constraint characteristics of planar mechanisms, the topological structure of 1T2R parallel mechanisms was regarded as consisting of a 1T1R planar parallel kinematic chain connected in series with a revolute joint and two spatial unconstrained active limbs. Then the topological structure optimization and performance verification of 1T2R parallel mechanisms were carried out by comprehensively considering the criteria such as appropriateness of mechanisms pose capability, rationality of branch-chain structure mechanics, reconfigurability of robot module, simplicity of position inverse solution, and compactness of moving platform structure,etc. Then, a new five-degree-of-freedom hybrid robot module that may inherit the advantages of Tricept robots was proposed. The module has exactly the same kinematics performance as Tricept robots, and most of the components may be interchanged with Tricept robots.
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    Multi-dimensional Dynamic Bayesian Network and Its Importance Measure Analysis Method
    CHEN Dongning, HU Yanlong, YAO Chengyu, WANG Kuantong, MA Lei,
    China Mechanical Engineering    2022, 33 (19): 2340-2346.   DOI: 10.3969/j.issn.1004-132X.2022.19.008
    Abstract263)      PDF (4440KB)(119)       Save
    The Bayesian network analysis method was an important method of reliability analysis, but the traditional Bayesian network analysis method was limited to analyze the influences of single factors, and there was a large analysis deviation when the system reliability was affected by multiple factors. Therefore, a multi-dimensional dynamic Bayesian network analysis method was proposed, which used unit step function and impulse function to construct Bayesian network time continuity, and established the failure probability distribution function when the root node was affected by multiple factors. Then, a multi-dimensional dynamic Bayesian network importance measure analysis method was proposed by expanding the traditional importance measure analysis method. Through the engineering example analyses of the hydraulic system of the bucket wheel machine tensioning mechanisms, and compared with the analysis results of the discrete-time Bayesian network analysis method, the feasibility and superiority of the multi-dimensional dynamic Bayesian network and its importance measure analysis method were verified, which provides a more accurate quantitative basis for system improvement and weak link identification.
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    Research on Backlash Elimination Method of Dual-motor Precision Transmission Mechanisms
    ZHENG Jieji, CHEN Lingyu, FAN Dapeng, XIE Xin
    China Mechanical Engineering    2022, 33 (22): 2684-2692.   DOI: 10.3969/j.issn.1004-132X.2022.22.005
    Abstract261)      PDF (6537KB)(120)       Save
    Aiming at the problems of large speed fluctuation and impact caused by the gaps between the two transmission chains of the dual-motor precision transmission mechanisms, the method of eliminating the gaps of the system was studied. First, a mechanism dynamics model including the meshing clearances between the output gear of the planetary reducer and the large ring gear was established. Through the model simulation, the influences of the gap size on the system characteristics were analyzed. Then, a compound anti-backlash method was proposed combining dynamic bias torque based on speed command and cross-coupling synchronous control based on differential negative feedback. An experimental device for dual-motor precision transmission mechanisms was built, and the verification experiments of the anti-backlash method were carried out. The experimental results show that in the case of closed-loop speed, the proposed compound anti-backlash method may ensure the complete elimination of the system gaps, and may improve the system speed tracking accuracy by 73.38%, and the shock amplitude in the start-up phase may be attenuated by 76.35%. The research results lay a certain foundation for the research of the high-precision control method of the double-motor precision transmission mechanisms, and provide a reference scheme for the elimination of the gaps in the gear transmission systems. 
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    Numerical Simulation on Mounted Bolt Failures in Vehicle Subframe 
    LI Wei, ZHENG Hao, LIU Yanmei, FAN Song
    China Mechanical Engineering    2022, 33 (19): 2388-2393.   DOI: 10.3969/j.issn.1004-132X.2022.19.014
    Abstract254)      PDF (5933KB)(119)       Save
    A high-strength mounted bolt(10.9, M14)was taken as the research object, 3 bolt strength tests were designed for different loading status. The fracture strain under different stresses triaxiality was calibrated using finite element simulation and parameter reverse methods and CrachFEM shear failure model was constructed for bolt material. The shear fracture strength was studied for variable diameters of mounted bolt during tests and simulation for subframe, and it provides the stable simulation method for mounted bolt design for subframe to satisfy the crash requirements. The correlation work also demonstrates that CrachFEM model may better predict the fracture failure behavior of high-strength mounted bolts. 
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    Study on Mechanics Properties and Numerical Convergence of Gyroid Cellular Structures
    JIANG Chuangyu, ZHANG Baoqiang, CHEN Yun, WANG Cunfu, LUO Huageng, HU Jiexiang, CAO Longchao
    China Mechanical Engineering    2022, 33 (23): 2790-28000.   DOI: 10.3969/j.issn.1004-132X.2022.23.003
    Abstract254)      PDF (14171KB)(73)       Save
    In order to reveal the corresponding relationship between TPMS structure design and mechanics property parameters, the mechanics properties of Gyroid cellular structure(GCS) with different arrangements and the numerical convergence of meshes with different parameters were studied. GCS specimens with fixed volume fraction and unit size were designed. Based on the voxelization model with changing mesh parameters, the convergence analyses of GCS were conducted by finite element method. The correctness of the simulation was verified by tensile test of specimen. Finally, the mechanics properties of the GCS in different arrangements were studied in tensile and bending conditions. Results show that the relative errors of tensile strength and load limit between simulation and experiment are all less than 1.5%. Based on the voxelization method, the number of elements during convergence  may be significantly reduced by adjusting the Jacobian parameters. Quantitative analyses of mechanics properties of variable thickness GCS were conducted. In tensile tests, for 4×4×4 structures, the maximum variation of equivalent elastic modulus along the thickness direction may reach 14.41%. In bending tests, for 20×4×4 structures, the maximum difference of equivalent elastic modulus is as 21.25%. 
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    Evolution of Concept of Machine Composition from the 19th Century to Modern Time
    ZHANG Ce, YANG Tingli, LIU Jianqin
    China Mechanical Engineering    2023, 34 (10): 1135-1139.   DOI: 10.3969/j.issn.1004-132X.2023.10.001
    Abstract253)      PDF (2405KB)(319)       Save
     With increasing of productivity and development of machines, the concept of “machine composition” also evolved. The requirements of modern society for machines were gradually increasing, and complex machines came from the transformation of traditional machines. Understanding the evolution of machines was a necessary process for the transformation of traditional machines. Marx first described the composition of machines in his Das Kapital, which coincided with the start of the Second Industrial Revolution. However, within only a few years, the control system joined a machine, and Marxs “concept of machine composition” began to be broken through. In the second half of the 20th century, in the Third Scientific and Technological Revolution, the concept of mechatronics emerged, and electronic technology, control technology and sensor technology were integrated into mechanical systems. The evolution processes of the concept of machine composition were explained through the history of the development of machines herein. By analyzing the evolution of the concept of machine composition, a more accurate definition of modern mechanical systems was put forword. It may enlighten people, increase their understanding of the machine itself, which has guiding significance for modern mechanical product designers. 
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    Design of Hobbing Motion Chamfering Tools for Cylindrical Gears
    HE Kun, HE Xiaohu, DU Yanbin
    China Mechanical Engineering    2022, 33 (22): 2704-2710.   DOI: 10.3969/j.issn.1004-132X.2022.22.007
    Abstract252)      PDF (6802KB)(129)       Save
    Aiming at the high-speed tooth profile chamfering requirements of cylindrical gears in actual productions, a new method of continuous cutting hobbing motion chamfering was proposed, and the profile design of the hobbing motion chamfering tools was completed. First, referring to the hobbing motion of cylindrical gears, the initial position relationship between the tool and the gear and the tool installation pose coordinate system were established, and the tool installation pose parameters were calculated through the chamfering parameters and the established installation pose coordinate system. Secondly, according to the chamfering motion and tool installation pose, a spatial motion coordinate system and derive the transformation relationship between the coordinate systems, and a tool profile calculation method was established by continuously solving the contact point between the tool rake face and the gear chamfering target profiles. Finally, a certain type of cylindrical helical gear was selected as the chamfering object. The three-dimensional modeling of the gears and the hobbing motion chamfering tools was completed by the cutting simulation software, and the chamfering cutting simulation was realized by writing the simulation motion program, the processing experiments were performed by chamfering machine. The simulation and experimental results show that the designed chamfering tool may meet the requirements of efficient tooth profile chamfering of cylindrical gears, and the correctness of the tool profile calculation method is also verifies.
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    Friction Model of Robot Joints Considering Influences of Temperature
    ZHANG Yinan, DING Jianwan
    China Mechanical Engineering    2023, 34 (02): 127-134.   DOI: 10.3969/j.issn.1004-132X.2023.02.001
    Abstract251)      PDF (3917KB)(159)       Save
     In order to describe the influences of temperature on serial robot joint friction under continuous operations, a joint friction model was proposed considering the influences of temperature. This friction model might describe the effects of joint temperature changes on joint friction without measuring or estimating temperature. Through experiments, the friction torques of the robot joints were measured as the joint operations continuously at different angular velocities, and the data were fitted based on the theoretical model. By comparing the experimental results, the validity of the joint friction model was verified. This model may describe the variation of joint friction torques more accurately under continuous operations. 
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    Research on Prediction and Control Method of Workpiece Tooth Flank Texture during Internal Gear Power Honing
    HAN Jiang, LI Zhenfu, TIAN Xiaoqing, FEI Ningzhong, XIA Lian,
    China Mechanical Engineering    2023, 34 (01): 10-16.   DOI: 10.3969/j.issn.1004-132X.2023.01.002
    Abstract249)      PDF (3961KB)(117)       Save
    Taking the internal gear power honing process as the object, the formation mechanism of the honing texture of the workpiece tooth flanks was studied, the honing texture was predicted, and an active control method of the honing texture was proposed. Firstly, a tooth flank contact line model of the workpieces was established to simulate the honing process. Secondly, the principle of the honing wheel dressing process was studied, and the mapping relationship between the honing speed and the machining texture was obtained. Since the honing speed was controlled by the parameters such as center distance and the cross-axis angle of the workpiece gear and the honing wheel, a control method for the distribution and change trend of the tooth flank texture of the workpieces was proposed, taking the cross-axis angle and the center distance as the control objects. Finally, the gears were machined with different processing parameters, and the three-dimensional morphology of the tooth flanks were detected. The measured results of the machined tooth flanks are highly consistent with that from the prediction models, which show the method herein may realize the texture control of gear honing. 
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    Time Domain Dynamics Topology Optimization of Functionally Gradient Material Structures with Self-weight Load
    WEN Guilin, CHEN Gaoxi, WANG Hongxin, XUE Liang, WEI Peng, LIU Jie,
    China Mechanical Engineering    2022, 33 (23): 2774-2782.   DOI: 10.3969/j.issn.1004-132X.2022.23.001
    Abstract249)      PDF (9631KB)(123)       Save
     A time domain dynamics topology optimization design method of FGM with self-weight load was developed. A structural self-weight distribution strategy of FGM-SIMP gradient materials was proposed under the framework of solid isotropic material with penalization(SIMP). The dynamics topology optimization formulations were established with minimum dynamic compliance as the optimization objective and structural volume as the constraints. The sensitivity was derived in the time domain based on the adjoint method and solved by the method of moving asymptotes(MMA). The topology optimization design of FGM structures with self-weight load was systematically analyzed through 2D and 3D typical numerical examples. Besides, the effects of the self-weight loads and the direction of material gradient distribution on the topology optimization results were deeply discussed. It is found that the self-weight loads and the direction of material gradient distributions have a significant influence on the optimal configuration and dynamic stiffness of the FGM structures. Finally, taking homogeneous materials(a special case of FGM)as an example, the validity of the proposed method was verified by numerical simulations and experiments, it is found that the proposed method may effectively improve the resonance frequency and dynamic stiffness. 
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    Intelligent Fault Diagnosis of Bearings with Few Samples Based on an Improved Convolutional Generative Adversarial Network
    GUO Wei, XING Xiaosong
    China Mechanical Engineering    2022, 33 (19): 2347-2355.   DOI: 10.3969/j.issn.1004-132X.2022.19.009
    Abstract246)      PDF (4512KB)(150)       Save
     Few bearing samples usually led to inadequate learning and low diagnosis accuracy. To solve this problem, an improved convolutional generative adversarial network was constructed. It made full use of data generation ability of the GAN and learning ability of deep CNN, so that the intelligent fault diagnosis might be conducted for the bearings with few samples under varying working conditions. First, a deep convolutional GAN was constructed. The deep features in few real data were mined through adversarial learning between the generator and discriminator of GAN, and then the generator might generate simulated data exactly like real one to make up for the lack of very few samples. Then, the dense block and dilated convolutions were combined with the CNN, named as DDCNN, to improve the learning ability by extending the network depth and perception range. As a result, the DDCNN may identify tiny differences in multi-class datasets and enhance feature extraction. Finally, the proposed method was verified by using bearing datasets with few samples under fixed conditions and varying rotating speeds, and was compared with other frameworks. The experimental results indicate that DDCNN has higher diagnosis accuracy for bearings with few samples and noisy conditions. 
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    Energy Footprint Modeling and Parameter Optimization in Workshop Manufacturing Processes
    TIAN Ying, SHAO Wenting, WANG Taiyong
    China Mechanical Engineering    2022, 33 (21): 2547-2553.   DOI: 10.3969/j.issn.1004-132X.2022.21.004
    Abstract243)      PDF (2327KB)(102)       Save
     To reduce the energy consumption during the parts manufacturing processes, an energy-saving focused multi-equipment machining parameter collaborative optimization method was proposed. Taking the workshop manufacturing processes with machines and robots as target, the energy footprint models considering cutting tool degradation processes were setup for the workshop system. Considering the cost index function of tool life and stability of robotic transportation, a multi-objective collaborative optimization model of machining parameters with multi-equipment systems was established. Taking the processing time as constraint, the artificial bee colony algorithm was used to obtain the global optimal parameters. Experimental results show that the optimized parameters may reduce the energy consumption of CNC machines by 17.97%, and reduce the energy consumption of the robotic transportation by 18.13%. 
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    Topology Optimization Design of Aero-engine External System Brackets for Additive Manufacturing
    MENG Liang, ZHONG Mingzhe, LI Wenbiao, XIA Liang, GAO Tong, ZHU Jihong, ZHANG Weihong,
    China Mechanical Engineering    2022, 33 (23): 2822-2832.   DOI: 10.3969/j.issn.1004-132X.2022.23.006
    Abstract242)      PDF (8396KB)(97)       Save
    The mechanics properties of aero-engine external system supports under critical loading conditions were analyzed. The support smoothness under two kinds of ultimate load conditions was used as objective function. The topology optimization design and performance check of external system supports for additive manufacturing were conducted using transverse isotropic model of additive manufacturing materials. The results of the mechanics test of metal laser additive manufacturing samples shows that, compared with the initial structure, the support design for additive manufacturing has a 15% less material usage, the stiffness increases by about 20%, and the first-order natural frequency improves by 15%. The structural strength increases significantly. The integrated additive manufacturing with 1 external system support, 2 piping supports and 4 rivets was realized herein, which effectively improves the quality and efficiency of engine assembly. The ground static load and engine ignition tests were successfully passed. 
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    Analysis and Comparison of Kinematic Characteristics for Two Typical 6-DOF Suspension Mechanisms at High Angles of Attack
    CHEN Hengtong, WANG Xiaoguang, JIANG Hailong, LIN Qi
    China Mechanical Engineering    2023, 34 (06): 641-649.   DOI: 10.3969/j.issn.1004-132X.2023.06.002
    Abstract242)      PDF (8317KB)(129)       Save
     To meet the requirements of multi-DOF (degree of freedom) coupled motion for the aircraft model, it was urgent to develop new suspension technologies. The motion characteristics of two typical six-DOF rigid and flexible parallel suspension mechanisms at high angles of attack were investigated. Firstly, a transverse 6-PUS rigid parallel suspension mechanism was designed, and the aircraft models pose workspace was solved based on the geometric and kinematic restraints. The mechanism stiffness matrix was also derived. As to the wire-driven parallel suspension mechanism, a symmetrical configuration with 8 wires was proposed and the dynamic motion workspace was obtained. By analyzing and comparing the workspace and internal frequencies of the two mechanisms, it is known that both of the rigid and flexible suspension methods may achieve large scale 6-DOF motion, but wire-driven parallel suspension system (WDPSS) has a larger workspace in the transverse and pitch motions with high natural frequency. Finally, the feasibility and effectiveness of WDPSS is experimentally validated through an example of pitch motions at high angle of attack. 
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    Research on Tool Tip Frequency Response Prediction of Robot Milling Systems Considering Characteristics of Spindle-toolholder Interface
    LIANG Zhiqiang, SHI Guihong, DU Yuchao, YE Yuling, JI Yongjian, CHEN Sichen, QIU Tianyang, LIU Zhibing, ZHOU Tianfeng, WANG Xibin
    China Mechanical Engineering    2023, 34 (01): 2-9.   DOI: 10.3969/j.issn.1004-132X.2023.01.001
    Abstract239)      PDF (5586KB)(164)       Save
    Aiming at the problems that the tool tip frequency response of robot milling systems was posture-dependent, which made it difficult to accurately predict the stability and effectively control the machining chatters in the process of robot pose changing, a prediction method of the tool tip frequency response of robot milling systems was proposed considering the contact stiffness of spindle-toolholder interface. Based on Euler-Lagrangian method and unit area method of Yoshimura, the dynamics model of robot body and the contact stiffness model of spindle-toolholder interface were constructed, respectively. Then, based on the theory of the main and auxiliary degrees of freedom of finite element, the dynamics model of robot body and the contact stiffness model of spindle-toolholder interface were combined to construct the prediction model of tool tip frequency response of robot milling systems. The verification test of tool-tip frequency response prediction under different postures of the robot was carried out. The results show that the maximum error of the natural frequency is as 6.63% and the maximum error of the corresponding amplitude is as 9.80% compared with the frequency response function of tool-tip obtained by simulations and experiments, which verifies the accuracy of the proposed prediction model and proves that the model may realize accurate prediction of frequency response function under any postures of the robot.
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    Research on Adaptive Cutting Control Strategy of Roadheader Cutting Arms
    WANG Dongjie, WANG Pengjiang, LI Yue, GUO Mingze, ZHENG Weixiong, SHEN Yang, WU Miao
    China Mechanical Engineering    2022, 33 (20): 2492-2501.   DOI: 10.3969/j.issn.1004-132X.2022.20.013
    Abstract237)      PDF (5692KB)(140)       Save
    Aiming at the problems of low intelligent cutting degree of underground roadheaders, and the swing speed of cutting arms might not be adjusted adaptively according to the hardness of coals and rocks, an adaptive cutting control strategy of roadheader cutting arms was proposed based on multiple sensor information. On the basis of the currents of the cutting motor, the pressures of the driving cylinder of the cutting arms and the vibration accelerations of the cutting arms, the signal recognizer of the cutting loads was designed by using RBF neural network, which provided an accurate basis for the swing speed control of the cutting arms. Aiming at the complex and time-varying swing speed control system of cutting arms, based on genetic algorithm optimization, a fuzzy PID intelligent controller was designed to realize the efficient control of swing speed of cutting arms. The mathematical model of cutting arms of roadheaders was established, and the adaptive cutting simulation control system of cutting arms was built in MATLAB/Simulink. The simulation results show that the control system has fast response speed and high control precision. An airborne adaptive cutting control system of roadheaders was built based on the software of B&R Automation Studio. The simulation cutting experiments were carried out with EBZ135 roadheader in the simulated roadway of Shijiazhuang Coal Mining Machinery Co., Ltd. the experimental results show that the proposed control strategy may realize the efficient adaptive control of the swing speed of cutting arms according to the changes of cutting loads.
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    Blind Deconvolution Based on Reweighted-kurtosis Maximization for Wind Turbine Fault Diagnosis
    WU Lei, WANG Jiaxu, ZHANG Xin, LIU Zhiwen
    China Mechanical Engineering    2022, 33 (19): 2356-2363.   DOI: 10.3969/j.issn.1004-132X.2022.19.010
    Abstract232)      PDF (6124KB)(97)       Save
    Due to influences of noise and complex transmission paths, the wind turbine gear fault signatures were generally weak. To effectively diagnose the gear faults, a new blind deconvolution method  was proposed based on reweighted-kurtosis maximization. The reweighted-kurtosis possessed great robustness to single or few strong impulse interferences and did not require any prior knowledge of the fault impulse train to be restored. The proposed deconvolution method may effectively solve the problems that the classical kurtosis maximization-based methods tend to restore a single dominant impulse rather than the gear fault impulse train. At the same time, the proposed method has stronger applicability in gear fault diagnosis for industrial equipment in comparison with the common non-fully “blind” methods(relying on the prior knowledge of the fault characteristic frequency). The analysis results of the simulated signals show that the proposed method is effective in restoring fault impulse trains. The applications in wind turbine fault diagnosis demonstrate the effectiveness of the proposed method for gear fault diagnosis. 
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    Scheduling of Flexible Job Shop Based on High-dimension and Multi-objective Migrating Bird Optimization Algorithm
    WANG Qiulian, DUAN Xinghao
    China Mechanical Engineering    2022, 33 (21): 2601-2612.   DOI: 10.3969/j.issn.1004-132X.2022.21.009
    Abstract232)      PDF (3476KB)(139)       Save
     Aiming at the problems in flexible job shop scheduling, an improved multi-objective migrating bird optimization(MOMBO)algorithm was proposed to solve the high-dimensional multi-objective scheduling problem with the consideration of maximum completion time, total delay period, total load of machine, and total energy consumption. On the basis of migrating bird optimization algorithm, MOMBO algorithm introduced a selection operator based on Pareto domination and reference point to give bird population selection pressure, and the combined weight method based on attribute hierarchical mode and gray relation analysis was used to select the most suitable solution from the optimal solution sets. The effectiveness and practicability of MOMBO were verified by test instances and case study. 
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    Based on Machine Learning Intelligent Design and Properties Research of Large Sectional High Strength Martensite Steels for Petroleum Equipment
    LI Fangpo, LU Caihong, ZHAO Jingxiao, LI Xiucheng, SHANG Chengjia
    China Mechanical Engineering    2022, 33 (19): 2325-2330.   DOI: 10.3969/j.issn.1004-132X.2022.19.006
    Abstract231)      PDF (5541KB)(133)       Save
    In order to develop new materials and meet the requirements of ultra-deep petroleum and gas development, four prediction models for composition-yield strength and composition-hardness of large cross-sectional martensitic steel with the highest strength grade for equipment components were established based on machine learning and composition performance big data herein. The results show that the artificial neural network model with 4 layers of neurons and 64 layers depth has the best fitting degree for property predicting, and two optimized martensitic steels chemical composition design with yield strength greater than 1100 MPa, hardness greater than 42HRC and carbon content less than 0.22% are formed based on genetic algorithm. The experimental results show that the hardening distribution curve of designed materials is basically consistent with the predicted values, and the maximum error is less than 3HRC. According to the optimized composition, 35 batches of products were manufactured and testing results show that the materials may meet the performance requirements of 150 mm cross-sectional drilling rig components. More than 95% uniform fine acicular martensite may be obtained in the full cross-sections, yield strength is greater than 1100MPa and impact absorbed energy is greater than 45 J which meets the service requirements of petroleum equipment. The results of prediction performance are consistent with that of experiments. Material big data is combined with machine learning, which provides a new way for developing high performance petroleum equipment materials.
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    Modelling and Analysis of Multiple-cross-springs Flexure Pivots with Arc Curved Beams
    CHEN Xin, LIU Jiangnan, LONG Wangpeng, LYU Jianwen
    China Mechanical Engineering    2023, 34 (03): 269-276,286.   DOI: 10.3969/j.issn.1004-132X.2023.03.002
    Abstract231)      PDF (8936KB)(116)       Save
    It was challenge to balance the large turning angle and low stiffness of multiple-cross-springs flexure pivots with straight beams. The multiple-cross-springs flexure pivots with arc curved beam springs was designed to reduce the maximum stress and rotational stiffness. The high rotation accuracy and large stroke were obtained under pure torque driving conditions. The calculation equation of deformation stress of the arc curved beam springs was deduced, and the large deformation mechanicals analysis model of the flexure pivots was established. The accuracy of the theoretical model was verified by the rotation stiffness experiments and the deformation stress simulation calculation. Moreover, the relationship among the driving torque and deformation stress of the flexure pivots and the design variables, radius coefficient, spring curvature and configuration angle was discussed by using the deformation model. Some design schemes to reduce the rotation stiffness and deformation stress concurrently were proposed. The appropriate variable combination for the flexure pivots to obtain zero stiffness characteristics and negative stiffness characteristics were determined. The designed flexure pivots and the rotation characteristics analysis results provide a reference for the design of a new type of large-stroke flexure pivots.
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