Table of Content

    10 May 2021, Volume 32 Issue 09
    Study on Tool Interface Behavior of Silicon Carbide Toughened Alumina-based Ceramic Tools in Cutting Inconel718 Alloy#br#
    HAO Zhaopeng, HAN Xue, FAN Yihang
    2021, 32(09):  1009-1016.  DOI: 10.3969/j.issn.1004-132X.2021.09.001
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    Through macro experiments, it was found that during the cutting processes, the Al2O3/SiC interface of the tool breaks, and the macro mechanical properties of the material depended on the microstructure. Therefore, the molecular dynamics model for the cutting of Inconel718 nickel-based alloy with ceramic tool toughened alumina based on silicon carbide and the three-dimensional interface model of Al2O3/SiC were established to analyze the interface behaviors of the cutting processes of toughened alumina based on silicon carbide from the atomic scale. Based on the original potential function, the Morse potential function between the tool and the workpiece atoms, as well as between the matrix and toughening inside the tool was calculated, and the interface binding energy of single-phase Al2O3, single-phase SiC and complex phase Al2O3/SiC single interface was calculated respectively. Results show that compared with single phase interface, the complex phase Al2O3/SiC interface bonding strength is higher, SiC toughening can enhance the toughness and strength of the tools. However, during the cutting processes, the workpiece atom diffuses into the tool, and the interface bonding energy between the tool matrix and the toughened interface is calculated. It is found that the diffusion reduces the interface bonding strength of the tools and makes the tool fracture at the interfaces of Al2O3/SiC.
    Design Calculation and Performance Analysis of Elliptical Corner-filleted Hybrid Flexure Hinges#br#
    WANG Chuanli, LI Cheng, HE Tao, CHEN Guoyu,
    2021, 32(09):  1017-1026.  DOI: 10.3969/j.issn.1004-132X.2021.09.002
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     In order to meet the large compliance requirements of compliant mechanisms, a new type of elliptical corner-filleted flexure hinge was designed. Firstly, the formulas of compliance and rotation accuracy were derived on the basis of the Castiglianos second theorem. Under the limit condition of parameters, the structure of elliptical corner-filleted evolved into three other hinge forms: right circular corner-filleted, elliptical right circular and right circular flexure hinge. The calculation formulas of compliance and rotation accuracy of various flexure hinges were combined in a set of equations. The correctness of the calculation formula was verified by the finite element analysis. Secondly, the influence trend of structural parameters on compliance, rotation accuracy and compliance accuracy ratio was discussed. The analysis results show that compliance and rotation accuracy have the opposite trend with the change of parameters, and reducing the minimum thickness is the best way to improve compliance. Then, the performances of four kinds of flexure hinges were compared. The results show that the elliptical corner-filleted hybrid flexure hinge has the maximum compliance but low rotation accuracy, while the right circular flexure hinge has the high rotation accuracy and superior comprehensive performance, but the minimum compliance. Finally, the examples of the elliptical corner-filleted and the right circular flexure hinge were applied and analyzed. The analysis results show that the novel flexure hinge has significant advantages in rotation range and stress level.
    Kinematic Accuracy Analysis and Optimization Design for Spatial Steering Mechanisms with Joint Clearances#br#
    WANG Chengzhi, WANG Yunchao
    2021, 32(09):  1027-1034,1042.  DOI: 10.3969/j.issn.1004-132X.2021.09.003
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     To evaluate the influences of the joint clearances, including the joint radial clearances and the rack moving direction inclination to lateral direction of vehicle, on the steering errors of a rack and pinion steering mechanism, the joint radial clearances in the steering mechanisms were treated as joint clearance link or variable length link, and then the kinematic model of the spatial steering mechanisms with the joint clearances and the analytical relationship between the rotation angles of kingpin axis and steering wheel were deduced by using the screw theory. An optimization model for the steering mechanisms was established by aiming at minimizing steering errors and taking the maximum values of pressure angles and the minimum value of the maximum steering angle as the constrained conditions. The kinematic analysis of an example shows that the forward and the return steering processes of the steering mechanisms with joint clearances have different steering errors and the return steering errors are larger than that of the forward steering; the steering errors at the moment of revering operation increase sharply; the increase of the joint clearance or the inclination of the rack may increase the minimum steering radius of the vehicle. Steering accuracy of the steering mechanisms with joint clearances may be improved by the optimal design considering the joint clearances. 
    Experimental Research on Interactions of Slotted Parameters for Rotary Distributing Excitation Control Valves#br#
    ZHAO Guochao, WANG Hui, SUN Yuanjing, ZHANG Changshuai
    2021, 32(09):  1035-1042.  DOI: 10.3969/j.issn.1004-132X.2021.09.004
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    A rotary distributing excitation control valve was proposed. In order to determine the influences of spool slotted parameters and the interaction on the output pressure of excitation control valves, the output pressures of excitation control valves was simulated based on multi-reference systems sliding grid method by Fluent, and the simulated results were verified by experiments. A significant regression model of slotted parameters and output pressure was established by using quadratic regression orthogonal test method and central composite test method.Through the analysis of ANOVA (analysis of variance), the significant difference and the response surface under the interaction of slotted parameters affecting the output pressure were obtained. The Influence trend for interaction of slotted parameters on the output pressures was discussed.The results show that in the test space, as the slot length, slot width and slot depth increase, the output pressures of excitation control valves increase by 8.3%, 25.1% and 22.3% respectively, the order of effective extent is width, depth and length. The interactions of slot width with slot length and depth have the most significant effect on the output pressures of excitation control valves.
    Multi-objective Optimization Decision of High-speed Dry Hobbing Process Parameters Based on GABP and Improved NSGA-Ⅱ#br#
    LIU Yifan, YAN Chunping, NI Hengxin, MOU Yun
    2021, 32(09):  1043-1050.  DOI: 10.3969/j.issn.1004-132X.2021.09.005
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    A method was proposed to optimize and decide parameters in the situation of high speed dry hobbing, supported by example prediction and multi-objective genetic optimization algorithm. Based on actual processing sample sets, the subject model was a variant of NSGA-Ⅱ, the optimization goal was the maximum tool life and the minimum energy consumption.The improved GABP neural network was used to construct a prediction model for the processing optimization fitness function, and a similar instance set of the hobbing problem was obtained through the DBSCAN clustering algorithm, so as to establish multi-objective optimization constraints, and construct the multi-objective optimization model for optimizing and deciding process, which may search the optimal processing parameters iteratively. 
    Stiffness Analysis of New Type Non-pneumatic Tires Based on Pseudo-rigid-flexible Body Coupling Model#br#
    2021, 32(09):  1051-1060,1072.  DOI: 10.3969/j.issn.1004-132X.2021.09.006
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    In view of the structural characteristics of new type pseudo-rigid non-pneumatic tires, a pseudo-rigid-flexible body coupling model was established to analyze the radial stiffness characteristics. The displacement equations of the plate spring and elastic wheel disks were coupled to solve the sinkage displacement and deformation of the tires, which were derived from pseudo-rigid body theory and elastic mechanics. The results show that there is linear relation between the sinkage displacements of pseudo-rigid non-pneumatic tires and the loads, and the tire radial stiffness is larger than ordinary pneumatic/non-pneumatic tires. Ride comfort of the tires is better when working at low speed and a little bit worse at high speed. To verify the above model, the finite element solution results were compared under the same boundary conditions. The results of the coupling model and the finite element method are close to each other, and the simulation time of the pseudo-rigid-flexible body coupling model is shorter. Finally, the radial stiffness of the tires was optimized by using the coupling model and the required design size parameters were obtained.
    Cloud Platform Data-informed Leader-follower Joint Optimization of Products and Supplier Resources#br#
    ZHANG Wei, HOU Liang
    2021, 32(09):  1061-1072.  DOI: 10.3969/j.issn.1004-132X.2021.09.007
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    There were some problems in the traditional research of product and supplier resource collaboration, such as demand response lag and distortion caused by historical data or experience input and based on “normalization” or “hierarchical optimization”. Based on the analysis of the forward and backward coupling interaction characteristics of the two sides and the analysis of the data transmission path, a decision-making method of the leader-follower joint optimization system for products and supplier resources was proposed based on the DID of the cloud platform. Firstly, the collaborative configuration framework of products and supplier resources was constructed based on cloud platform DID. Secondly, the leader-follower joint optimization decision model was established based on cloud platform DID. Among them, the product configuration based on the positive customer demands acted as the leader, and supplier joint configuration acted as the follower to influence the decision-making of product configuration. The model trade-off solution was optimized by using bi-level nested genetic algorithm. Finally, a case of collaborative optimization between products and supplier resources of automobile seats was given. The results show that the proposed method has significant advantages in real representation of transfer and collaborative relationship of product and supplier joint configuration process.
    A SOM-FWFCM Based Feature Selection Algorithm for Order Remaining Completion Time Prediction#br#
    LIU Daoyuan, GUO Yu, HUANG Shaohua, FANG Weiguang, YANG Nengjun, CUI Shiting
    2021, 32(09):  1073-1079.  DOI: 10.3969/j.issn.10041132X.2021.09.008
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    Accurate ORCT prediction was helpful to adjust production schedule and optimize manufacturing processes dynamically, which ensured timely orders delivery. ORCT affected by various production factors, including materials, equipment, works-in-process, et al. The related data possessed typical characteristics of large-scale, multi-dimensions and high-redundancy. Effective feature selection might improve the prediction accuracy. On the basis of constructing candidate feature sets, a feature selection algorithm was proposed based on SOM-FWFCM algorithm. Firstly, the cluster centers of FWFCM algorithm were initialized by SOM network to reduce the reliance on initial cluster centers. Feature weights were calculated by mutual information to achieve feature clustering with guidance. Then, according to the cluster results, representational features were selected to build high-quality key feature subset. Finally, taking the production data of a machining shop as an example, the effectiveness of the proposed algorithm was verified by comparing with other four feature selection algorithms.
    Selective Asynchronous Parallel Disassembly Sequence Planning Considering Indeterminate Degree of Disassembly#br#
    GUO Jun, WANG Zhendong, DU Baigang, LI Yibing,
    2021, 32(09):  1080-1090,1101.  DOI: 10.3969/j.issn.1004-132X.2021.09.009
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    In view of the facts that the selective disassembly planning method commonly used in the recycling of waste products which might not fully considered the regeneration benefits of all parts, a method of selective asynchronous parallel disassembly sequence planning with an indeterminate degree of disassembly was proposed. The connection relation and priority constraint relation among product parts were expressed by the disassembly hybrid diagram. Based on this, the minimum required set of parts to be searched in the reverse direction was taken as the lower limit of the disassembly set to obtain the set with different disassembly degrees. Then a mathematical model was established with the optimization goals of minimum disassembly time and maximum disassembly profit, and an improved biogeographic-based optimization algorithm was proposed for solution optimization. Combined with the characteristics of the disassembly sequence planning problem, a coding method was designed based on three-layer linked list, and a random topology structure was used to improve the global search ability and local search ability of the algorithm. Finally, a mechanical arm and a two-stage cylindrical bevel gear reducer were studied as instances to demonstrate the feasibly and efficiency of the method presented.
    Analysis of Influence Laws of Blank Substrate Morphology on Powder Flow Field of Remanufacturing Coaxial Powder Feeding#br#
    GUO Chenguang, LYU Ning, GUO Hao, LI Qiang, YUE Haitao,
    2021, 32(09):  1091-1101.  DOI: 10.3969/j.issn.1004-132X.2021.09.010
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    The reflection of gas-powder impinging on the substrate surface was an important factor to affect the forming quality and efficiency for laser additive remanufacturing. Due to the various substrate shapes, the changes of the powder flow field were different after the powder impinging on the substrates. Gas-solid two-phase flow was taken as the theoretical basis, coupled simulation of EDEM and FLUENT software was used to study the gas-powder flow field distribution characteristics under three kinds of substrate changes, namely, regular substrate boundary, thin-wall substrate thickness and globoidal substrate curvature, and experimental verification was carried out. Results show that the turbulence of the gas field in the contact areas with the substrate increases as the nozzle is far away from the boundary, and the low-speed areas as well as the negative pressure range decreases. Meanwhile, the number of effective particles decrease exponentially. The gas field developes to the both sides obviously and the concentration of the machining centers decreases gradually with the increase of the thin-walled substrate width. And the powder flow rate in the effective ranges increases first and then remains. With the increase of the absolute curvature of substrates, the radial concentration of the convex substrate increases, and the focus range decreases, and the powder flow has a better convergence than that of concave substrates.
    Load Balancing Heterogeneous Parallel Slice Algorithm for Metal Additive Manufacturing#br#
    LI Huixian, MA Chuangxin, WANG Shuo, MA Liang
    2021, 32(09):  1102-1107.  DOI: 10.3969/j.issn.1004-132X.2021.09.011
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    The geometric complexity and volume of additive manufacturing models continued to increase, and the time required for model slicing increased greatly, which greatly affected the efficiency of data processing. An adaptive load balancing heterogeneous parallel slicing algorithm was proposed. Using the growing parallel computing power of GPU, the traditional slicing algorithm was GPU parallelized, and the simulated annealing algorithm was used to load balance the slicing tasks, so that the task amount among the threads was consistent. Experimental results show that the algorithm improves the slicing efficiency of the model, and is especially suitable for fast slicing tasks of large or super large 3D models.
    Effects of STL Data Processing on Surface Stripes of Laser Sintered Parts
    SUN Maoyin, WU Jian, WU Zehong,
    2021, 32(09):  1108-1113.  DOI: 10.3969/j.issn.1004-132X.2021.09.012
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    The surface stripes of nylon SLS parts for STL was studied. Based on the principle of SLS technology, storage rules of STL and formation principle of laser scanning path, the nylon SLS experiments of STL were designed, and the formation mechanism of surface stripes of STL model data sintered parts was analyzed. A method was proposed to avoid the formation of stripes.The experiments and analysis show that the surface stripes are caused by the absence or redundancy of triangles in the model data plane when the system software reads the data. The surface stripes are related to the Z coordinate value of STL in the forming coordinate system, and have certain regularity with the actual sintering layer thickness. STL surface fringes may be avoided by homogenizing the triangle of STL or making its Z coordinate values not in specific coordinates.
    Low-observable Target Detection Method for Autonomous Vehicles Based on Multi-modal Feature Fusion#br#
    ZOU Wei, YIN Guodong, LIU Haoji, GENG Keke, HUANG Wenhan, WU Yuan, XUE Hongwei
    2021, 32(09):  1114-1125.  DOI: 10.3969/j.issn.1004-132X.2021.09.013
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    Aiming at the problems of low-observable target detection in autonomous vehicles under real driving conditions, a target detection method was proposed based on multi-modal feature fusion. In order to improve the detection on the low-observable targets, the multi-modal deep convolutional neural network was designed based on Faster R-CNN to fuse the features of RGB images, polarized images and infrared images, the development of the multi-modal (three) image low-observable target real-time detection system was studied and the applications of multi-modal image feature fusion in the intelligent perception system of autonomous vehicles were explored herein. A manually labeled multi-modal image dataset of low-observable targets was built. The deep learning neural network was trained to optimize internal parameters to make the system capable for both pedestrians and vehicle recognition in the complex environments. The experimental results indicate that the deep convolutional neural network based on the multi-modal fusion has a better performance on the low-observable target detection and recognition in complex environments than that of traditional single-modal methods.
    An Improved ACO Algorithm for Automobile Mixed-flow Assembly Scheduling Problems#br#
    LI Yi, TANG Qian, LIULianchao, PENG Xiaogang, YAN Xianhong
    2021, 32(09):  1126-1133.  DOI: 10.3969/j.issn.1004-132X.2021.09.014
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    Since overload work stations were common and the vehicle assembly quality could not be guaranteed in mixed-model lines which involved a great deal of manual and human-machine operations, a bi-objective car sequencing model was proposed with load balancing at the bottleneck selection as a primary criterion, and minimizing the number of processing delay when considering the replacement and advanced operation time as a secondary criterion. Besides, an improved ACO was designed which used a specific heuristic function in the processes of pheromone global update and probability transfer rules, and changed the evaluation method of the optimal solution in the iterative processes. Compared with traditional ACO and genetic algorithm, computational experiments illustrate that both objectives may be effectively solved using the presented ACO algorithm. In addition, the algorithm may also reversely compute the planned production cycle when the second objective value is zero, which has certain guiding significance in vehicle production.