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  • WU Qilin, ZHAO Han, CHEN Xiaofei, ZHAO Yating
    Journal of Mechanical Engineering. 2023, 59(15): 1-16.
    As labour shortages and labour costs continue to rise, more and more robots are needed in growing numbers. In many application scenarios, the tasks are complex and varied, the application environment and the conditions are so varied that single-arm collaborative robots are no longer meet the requirements and multi-arm collaborative robotic systems have emerged as an important area for future development. Because of the short time frame for development, a great deal of work is still needed by developers. This research summarizes the current state of technology and applications of multi-arm collaborative robots in a more systematic way and reviews several influential aspects of multi-arm collaborative robots such as applications, mechanism and lightweight, dynamics and control, cooperative technology, and artificial intelligence. On this basis, six directions for future research and development of multi-armed collaborative robots are proposed, based on new developments in artificial intelligence and control, such as the development of application scenarios towards deep human-robot collaboration, more emphasis on high speed, high precision and high work-to-weight ratio in structures and components, and more emphasis on smooth design in dynamics. The collaborative robot system will also develop in a hierarchical and diversified manner, with control methods tending towards adaptive and flexible control and autonomous decision-making, and interaction tending towards multi-dimensional safety protection and natural interaction with multi-information fusion.
  • SHA Jingwei, FAN Mengbao, CAO Binghua, YANG Xuefeng
    Journal of Mechanical Engineering. 2023, 59(24): 1-17.
    The hardness of metallic components is a crucial indicator of their mechanical and physical properties, making hardness testing an important aspect of industrial production. Traditional methods of hardness testing, such as indentation or scratch tests, suffer from issues such as high destructiveness and low efficiency, rendering them unsuitable for modern testing needs. Therefore, non-destructive testing methods have emerged as a research hotspot. With the development of acoustic and electromagnetic technologies, non-destructive hardness testing techniques based on these technologies have been developed. Herein, a systematic description of non-destructive hardness testing techniques based on acoustic and electromagnetic methods is presented, and the influence of different material microstructural changes on the detection characteristics is explored. Through an analysis of the relationship between characteristics and microstructural changes, a deeper understanding of the principles and applications of non-destructive hardness testing techniques is gained. Subsequently, novel signal processing methods based on neural networks are reviewed, which have shown great potential in improving detection accuracy and optimizing signal processing algorithms. Finally, future development trends of non-destructive hardness testing techniques are discussed.
  • WANG Shuancheng, YANG Bing, LIAO Zhen, XIAO Shoune, KANG Guozheng, YANG Guangwu, ZHU Tao
    Journal of Mechanical Engineering. 2023, 59(16): 32-53.
    The short fatigue cracks of metal materials are systematically sorted out in terms of their definition, classification, test methods, initiation mechanism, and typical growth rate models, as well as the problems facing the current research on short crack behavior, are summarized and prospected. The results show that the microstructure of materials plays an important role in the initiation and propagation of short cracks. When the crack tip reaches the grain boundary, the growth rate of cracks decelerates due to the influence of grain orientation and grain boundary resistance, and the short crack propagation path appears to be locally deflected after the crack tip breaks through the grain boundary constraint. In terms of the short cracks propagation behavior description, the driving force of short crack propagation is related to the load level, residual stress, surface treatment and local wear condition, and so on. During propagation, the crack tip materials yield in a small area and produce a local plastic zone. At the same time, the plastic wake is gradually formed, which results in plastic-induced closure and a decrease in the crack propagation threshold value. Besides,the interaction between crystal dislocations and dislocation stacking can hinder the dislocation development. The machine learning algorithm, as an advanced technological tool, has been applied in the characterization of short crack growth behavior, which has contributed to the improvement of prediction accuracy. With further research on the behavior of short cracks in metal materials, we can focus on real-time monitoring of short crack initiation and propagation, control of test influencing factors, discrete data analysis,and engineering applications of the growth rate model in the future. The establishment of a unified characterization model for long and short crack growth rate as well as real-time monitoring and safety assessment techniques will be explored. In addition, more effective and accurate safety assessment and remaining life management of critical metal structures can be realized by combining advanced machine learning algorithms.
  • Li Fei, Zhang Huayu, Chen Huiqin
    Forging & Stamping Technology. 2023, 48(8): 231-237.
    The mechanical behavior and microstructure evolution of Mn18Cr18N steel under cycle loading in the strain amplitude range of±0.005-±0.10 were studied by room temperature tension-compression cycle loading tests. The microstructure evolution of Mn18Cr18N steel, including metallographic structure, dislocation morphology, deformation twins and other substructures, were observed by optical microscope and transimision electron microscope. The research results show that the cyclic mechanical properties of Mn18Cr18N steel are related to the strain amplitudes in the tension-compression cycle loading. With the increasing of cyclic strain amplitude, the cyclic stress amplitude of Mn18Cr18N steel shows an increasing trend. When the strain amplitude is ±0.10, the rheological stress of Mn18Cr18N steel is 988.1 MPa after one cycle loading, which is 1.6 times of the 0.2% initial yield strength. The research indicates that the cumulative plastic strain of Mn18Cr18N steel is increased by the cycle loading with large strain amplitude to significantly improve the strength. At a lower strain amplitude (±0.005-±0.01), the deformation of Mn18Cr18N steel is mainly plane slip, and the dislocation rearrangement and the activation of other slip systems are the main reasons for the cycle softening of Mn18Cr18N steel. When the strain amplitude is larger, the proliferation of high dislocation increases the internal stress of the matrix, the local area slips difficultly, the twinning mechanism is activated, and Mn18Cr18N steel generally exhibits cycle strengthening characteristics.
  • LUO Shijian, GONG Hebo, LIN Wei
    Journal of Mechanical Engineering. 2023, 59(11): 1-15.
    The vigorous development of artificial intelligence and internet of things technology supports the advancement of intelligent products and accelerates the transformation of product design. Technology can make human life better by being transformed into intelligent products through design. From industrial design, the related concepts of intelligent products and intelligent product interaction design are discussed through the research of relevant literature at home and abroad. In terms of research methods of intelligent product interaction design, three levels of models of the ontology, behavior, and value of intelligent product interaction design are proposed. This paper discusses the research content and architecture, key technologies, and existing problems of five aspects: design big data, demand-driven, and knowledge-driven design, product design scheme generation and derivation, product design standard generation, and product design scheme evaluation generation. The process and method of interaction design of intelligent products are summarized. Finally, according to the integrated development of interaction design and artificial intelligence technology, some focused research issues on intelligent products interaction design are formulated, and the future development trend is outlined.
  • GAO Zhi-guo, XU Wu-feng
    Transactions of Materials and Heat Treatment. 2023, 44(6): 11-19.
    Al-xCu aluminum alloys have received extensive attention and research due to their excellent mechanical properties and corrosion resistance. However, under extreme service conditions such as high temperature and high-speed impact, the excellent properties of the Al-xCu aluminum alloys have deteriorated significantly, which can not meet the requirements of specific working conditions. This is mainly due to the lower stability of the alloy due to the change of the aspect ratio and volume fraction of the θ' precipitated phase during service. In this paper, the basic principles of controlling the stability of the θ' precipitates in the Al-xCu alloys by microalloying, external stress aging and dislocation are reviewed. The problems of controlling the stability of the θ' precipitated phase in the Al-xCu alloys are discussed, and the future development and research focus are prospected.
  • YU Zhihui, LIANG Jun, WU Dechao, LIU Jiguang, WANG Yuanxian
    China Foundry Machinery & Technology. 2023, 58(4): 63-68.
    Based on the structural characteristics and relevant casting technical requirements of an HT200 headstock, the corresponding casting process parameters have been determined through structural and process analysis of the casting, while the preliminary design of the pouring system has been completed.The pouring, filling, and solidification processes of molten metal have been simulated by use of computer software.By setting and adjusting the size and position of the riser and cold iron, the shrinkage porosity and porosity defects in the casting have been significantly reduced, while the optimal casting process plan has been obtained.
  • TAO Fei, ZHANG Chenyuan, LIU Weiran, ZHANG He, MA Xin, GAO Pengfei, ZHANG Jiankang
    Journal of Mechanical Engineering. 2023, 59(13): 193-215.
    Relying on physical methods for planning, research, design, manufacturing, test and use of products or systems is usually constrained by time, space, cost and safety, leading to problems such as long development cycle, high operating costs, delayed response, low intelligence, and difficult system optimization. In order to address the above problems, the theory of digital engineering is introduced, which strives to fully utilize both the 'digital power' and 'intelligence power' to enhance the 'capability'. In this paper, firstly a five-phase maturity model of digital engineering is proposed to better understand, further develop and fully utilize of digital engineering based on the analysis of the current digitalization and intelligentization practices and its future development trends. Then, the 'digital power', 'intelligence power' and 'capability' of digital engineering are defined, and the demands and challenges of digital engineering in the era of New IT are expounded in detail. Furthermore, the architecture of digital engineering is designed, which consists of one 'intelligence center' and four threads (physical thread, model thread, data thread and service thread), and eight key supporting technologies are also put forward. Finally, the application outlooks of digital engineering in ten fields are discussed, including digital nuclear power plant, digital aero-engine, digital satellite internet, digital ocean and marine equipment, digital wind tunnel, digital battlefield, digital city, digital computer numerical control machine, digital energy and digital vehicles, expecting to provide references for the scientific organization, intelligent control and system optimization of complex products and systems throughout lifecycle, as well as the construction of digital earth and the development of digital economy.
  • CHEN Xuedong, FAN Zhichao, CHEN Yongdong, XU Shuangqing, CUI Jun, ZHANG Xiaohu, GUAN Weihe, AI Zhibin
    Journal of Mechanical Engineering. 2023, 59(20): 18-33.
    Pressure vessel is a kind of pressure-bearing special equipment with a large quantity and wide applications, showing the potential hazard of leakage and explosion. China lists pressure vessels as high-end equipment, requiring to improve product quality and core competitiveness. Since the beginning of this century, scientific and technological workers in China have continued to carry out research and exploration and engineering practice in pressure vessel design and manufacturing under extreme conditions, lightweight green manufacturing of heavy-duty pressure vessels, risk-based integrity management, digital design, manufacturing and maintenance, etc. The applications of these achievements have made China’s petrochemical plant high-end pressure vessels basically no longer rely on imports, the level of green manufacturing technology has been significantly improved, and the long-term operation and maintenance capability has been significantly enhanced. This paper first briefly reviews the progress of pressure vessel design, manufacturing and maintenance technology in China since the beginning of this century. Focusing on major national strategies such as advancing new industrialization, moving faster to boost China’s strength in manufacturing and product quality, implementing industrial infrastructure reengineering projects and major technical equipment research projects, the technical problems that need to be solved urgently are elaborated from four aspects including robust industrial foundations, extreme manufacturing, green manufacturing and smart manufacturing. Facing the new application scenarios and the application of a new generation of artificial intelligence technology in the next two decades, the development trend of pressure vessels is technically foreseen.
  • MAI Ge-ma
    Foundry. 2023, 72(7): 937-938.
  • ZHANG Lei, XU Tongliang, LI Siyang, CHENG Shuhui, DING Xiaolin, WANG Zhenpo, SUN Fengchun
    Journal of Mechanical Engineering. 2023, 59(20): 261-280.
    Chassis coordinated control for full X-by-wire distributed-drive electric vehicles can effectively enhance both safety and ride comfort during vehicular operation. Taking vehicle safety and ride comfort as objectives, this paper provides a comprehensive review of key technologies and challenges in the chassis coordinated control for full X-by-wire distributed-drive electric vehicles, encompassing handling stability control, fault-tolerant control, vehicle attitude control, and ride comfort control. For handling stability control, traction control and anti-lock braking methods are introduced. A systematic analysis is conducted to evaluate the advantages and disadvantages of using one single or multiple X-by-wire subsystems in lateral and roll vehicle stability control. Regarding fault-tolerance control, the paper outlines fault-tolerant control strategies that use direct yaw-moment control to complement steer-by-wire systems. The paper summarizes methods for pitch attitude control and ride comfort control using one single or multiple X-by-wire subsystems. It emphasizes the importance of simultaneously addressing vehicle attitude and ride comfort to enhance control adaptability in complex operating conditions. Finally, the paper provides insights into future directions in chassis coordinated control.
  • JIN Chuan-wei, ZHANG Ji-ming, WU Yuan-yuan
    Transactions of Materials and Heat Treatment. 2023, 44(6): 143-149.
    Martensite and austenite(MA) islands thin film samples of acicular ferrite X65 pipeline steel were accurately prepared by focused ion beam(FIB) etching method. The substructure of MA islands was characterized by electron backscatter diffraction(EBSD) technique and transmission electron microscopy(TEM), and the role of MA islands in fatigue crack propagation was studied. The results show that the MA content in the acicular ferrite X65 pipeline steel is about 5.7%, and MA islands are mainly distributed at grain boundary, with size ≤ 3 μm. The internal substructure of MA islands is divided into several blocks with different sizes by martensite and retained austenite. The retained austenite and martensite distribute alternately in the MA islands, and there is a coherent relationship between martensite and austenite in some areas. The alternately distribution of retained austenite and martensite in MA islands has a significant inhibition effect on fatigue crack propagation. When the fatigue crack propagation path encounters MA islands, the main crack propagation direction deflects and bypasses MA islands, while the branch crack is captured by MA islands and stops propagation.
  • Plant Maintenance Engineering. 2023, 0(15): 160-162.
    主给水泵负荷随机组功率变化,泵轴轴系应力变化大,泵组对中情况在运行工况下变化大,泵组停运检修时建议复测检查对中数据,发现数据超出联轴器设计可补偿范围时,需警惕膜片联轴器膜片发生疲劳断裂。轴功率大于6 MW的泵组由于在运泵组本体设计和运行工况无法改变,泵组轴系膨胀情况无法改善,最终通过重新设计联轴器,选取2.7的选型工况系数,提高联轴器抗疲劳强度解决膜片断裂问题。
  • DAI Jiajia, GONG Xiaoxi, WANG Jun
    Journal of Mechanical Engineering. 2023, 59(16): 243-253.
    A coverage path planning algorithm based on the improved WaveFront algorithm is proposed for the full coverage path planning problem of unmanned aerial vehicles(UAVs) in the 3D environment in aircraft inspection tasks. Investigating a method for extracting viewpoints on the surface of 3D models based on discrete 3D grid maps. Improving the WaveFront algorithm according to the constraint strategy of adjacent viewpoints to solve the local optimum problem caused by the same loss value in different directions.Designing the orientation evaluation function in 3D space, which, combined with the viewpoint position, can guide the forward direction of the UAV. Realizing the UAV coverage path planning based on the 3D model for the aircraft surface. The experimental results show that the algorithm can realize the automatic extraction of viewpoints on the aircraft surface, and combined with the viewpoints can autonomously plan the flight path of the UAV. Compared with the genetic algorithm, the improved WaveFront can effectively carry out path planning on the aircraft surface and ensure that the UAV maintains a collision-free state with the aircraft fuselage. According to the planned path, the UAV can complete the task of detecting the surface of the aircraft fuselage without omission.
  • ZHANG Rui, ZENG Xiangjin, XU Cheng
    Packaging and Food Machinery. 2023, 41(4): 96-101.
    For the problems of limited cargo information,collision and physical stability limitation in the 3D boxing problem,an online 3D boxing method based on constrained deep reinforcement learning was proposed.This method uses the improved heuristic search algorithm to predict the feasibility mask of placing actions,and uses this mask to adjust the action probability output by the policy network during training.The experimental results show that the algorithm improves the boxing efficiency of disordered mixed goods,the average placement time of a single cargo is only 3.9 ms,and the space utilization rate reaches 68%.The study provides a useful reference for the application of reinforcement learning in the field of combinatorial optimization.
  • Research·Review
    Yuan Zizhou, Lang Yapeng, Zhang Xiangyun
    Special Casting & Nonferrous Alloys. 2023, 43(8): 1036-1040.
    Bulk amorphous composites are a kind of structural material with excellent mechanical properties, which overcome the room-temperature brittleness of amorphous alloy and retain high strength. The investigation of superplastic deformation behavior in the supercooled liquid region can not only guide the establishment, development and perfection of theoretical model, but also accelerate the engineering application of materials.The research status on superplastic forming of bulk amorphous alloys as well as its composites were briefly introduced, focusing on the superplastic rheological behavior of bulk amorphous composites in the supercooled liquid region, microstructure evolution and variation of mechanical properties during superplastic deformation. Finally, some technical problems to be solved in superplastic forming of amorphous composites were put forward.
  • PENG Siwen, LIANG Ke, PAN Lei, WANG Yupeng
    Modular Machine Tool & Automatic Manufacturing Technique. 2023, 0(6): 31-34.
    To improve the working efficiency and stability of the manipulator, a time-optimal 3-5-3 polynomial interpolation trajectory planning algorithm based on the improved particle swarm optimization algorithm was proposed.The local and global search capability of the algorithm is optimized by dynamically adjusting the inertia weight and learning factor.Taking the UR5e robot as the research object, the joint position sequence corresponding to the path point at the end of a given manipulator was obtained through inverse kinematics, and the motion trajectory in joint space is fitted by piecewise polynomial.Then, under the velocity constraint, the improved particle swarm optimization algorithm is used to optimize the trajectory of the manipulator.Finally, the simulation and experimental analysis are carried out by MATLAB software.The results show that the improved algorithm has significantly improved convergence speed and optimization accuracy, and effectively reduces the time for the manipulator to complete the target task.
  • LYU Shufan, DU Yuhong, LIU Tong
    Machine Tool & Hydraulics. 2023, 51(14): 113-117.
    In order to measure the friction torque of bearings at different temperatures,a new type of bearing friction torque measurement equipment was designed based on the measurement principle of the transfer method.The process hole in the lower layer of the incubator in the equipment was sealed with a sealed structure,and in view of the impact problem generated by the tested bearing and the measuring spindle during the docking,a new type of rat-like detachable clamp was designed to achieve a smooth transition.LabVIEW was used to write related motion control,data acquisition,and control interface programs.After the program was calculated and processed,the bearing friction torque value,change curve and other data were obtained.Finally,this equipment was used to measure the friction torque of SKF7207 deep groove ball bearings.The results show that the maximum repeatable measurement error of the equipment is 0.000 49 N·m,which has good repeatability and meets the design requirements.
  • Research·Review
    Jin Xiaolei, Zhao Fei, Hao Xianchao, Xing Weiwei, Wang Min, Ma Yingche
    Special Casting & Nonferrous Alloys. 2023, 43(8): 1029-1035.
    Nickel-based alloys possess excellent thermal strength and service stability, which are the widely used for high temperature applications.Cobalt was initially added in the development of nickel-based alloys to improve alloy properties. However, the role of Co in nickel-based alloys is still controversial. Effects of Co on microstructure, precipitation characteristics of the γ' phase, stability and mechanical properties of nickel-based alloys were investigated, and Co action mechanism was analyzed from the aspects of effects and indirect effects.Moreover, the possibility of saving Co and replacing Co was explored, aimng to provide theoretical basis for the development of novel nickel-based alloys and application of nickel-based alloy containing Co.
  • MENG Fan-ying, ZHANG Yi-fan, YANG Jia-hui, ZHANG Wei, WANG Lin, WU Jun-xia, LI Pei-you
    Transactions of Materials and Heat Treatment. 2023, 44(6): 20-27.
    The traditional catalytic alloy materials are mostly precious metals, while the high-entropy alloy catalytic materials reported in recent years are mostly cheap metal materials, and some of them have better catalytic properties than the traditional precious metals. This paper will systematically review the five aspects of electrocatalytic hydrogen evolution reaction(HER), electrocatalytic oxygen evolution reaction(OER), ammonia decomposition reaction(NH3), electrocatalytic oxygen reduction reaction(ORR), electrocatalytic carbon monoxide reduction(CORR) and electrocatalytic carbon dioxide reduction(CO2RR). Finally, the catalytic properties of the high-entropy alloys are summarized and the future research directions are prospected.
  • XIE Jiale, LI Zengchao, WANG Guang, YAO Tianqi
    Journal of Mechanical Engineering. 2023, 59(16): 342-352.
    The thermal safety of power batteries has been widely concerned by academia and industry. The temperature information of battery system is the essential reference to make efficient thermal management strategies. Specific to cylindrical batteries, lightweight lumped-parameter temperature prediction models are developed for embedded applications. Firstly, based on an equivalent circuit model, a mass-point(MP) temperature model is formulated according to basic electrical-thermal effects by regarding the cell as an isotropic homogeneous body. On this basis, the winding and shell parts of the cell are separately studied that surface heat dissipation,heat conduction delay and reversible heat are modeled in detail and related parameters are experimentally identified, thereby deriving an improved layered-divided(LD) temperature model to predict battery kernel(internal) and shell(external) temperatures. Finally,taking an 18650 li-ion battery as the object, experimental results under different temperatures and load conditions show that the temperature prediction performance of the LD model is obviously ameliorated in contrast to the MP model; the LD model can keep high reliability subject to various working conditions. Subject to hybrid pulse excitations, the max temperature error of the LD model is about 1 ℃ after 10 minutes of open-loop simulation.
  • WANG TingXuan, WANG GuiYong, LIU Tao, WANG ZhenYa
    Journal of Mechanical Strength. 2023, 45(3): 509-518.
    The complex and changeable working conditions of mechanical equipment in industrial field lead to uneven distribution of fault samples,which brings great trouble to traditional machine learning.In order to solve this problem,proposes a bearing fault transfer diagnosis method based on domain adaptive neural network and balanced dynamic distribution adaptive.Firstly,According to the characteristics of bearing vibration fault samples,the convolution layer of convolutional neural network is improved by wavelet transform,and the characteristics of bearing samples are extracted adaptively.Then,Maximum Mean Discrepancy measure and weight regularization are used to process the generated features in the loss function to reduce the difference in sample distribution and obtain the domain adaptive neural network model.Finally,A-distance is used to improve the equilibrium distribution adaptive to make it have dynamic characteristics,further improve the difference of sample distribution,and realize bearing transfer diagnosis by KNN classifier.Through experimental verification,the proposed method can accurately migrate the bearing fault state in the same bench rig cases and cross bench rig cases,proving that the method can effectively solve the problem of uneven distribution of unlabeled samples under variable working conditions,and has the effectiveness and robustness.
  • Plant Maintenance Engineering. 2023, 0(12): 106-108.
  • CHEN Zongping, CHENG Gong, SHENG Xiaozhen
    Journal of Mechanical Engineering. 2023, 59(16): 147-156.
    In order to explore the dynamic stiffness characteristics of the high-speed railway fastening system under low temperature and high frequency conditions,Taking the existing WJ-7B and WJ-8B fasteners as the research object, firstly, a test method and theoretical model to determine the overall dynamic stiffness of the fastening system are proposed. Secondly, the simulation models of the two fasteners are established, and the model was verified with the test results. Finally, the overall dynamic stiffness characteristics of the fastener and the influence of the clip on the overall dynamic stiffness are simulated and analyzed according to the establishend modal.The results show that the dynamic stiffness of WJ-7B is greatly affected by frequency. The dynamic stiffness at 950 Hz is 15-19 times higher than that at 100 Hz; The dynamic stiffness of WJ-8B fasteners is more affected by temperature, Under-50 ℃The dynamic stiffness of the WJ-8B is 23 times greater than that at 10 ℃; The dynamic stiffness of the WJ-8B fastener is much lower than the dynamic stiffness of the railpad at the first resonance frequency, This order of resonance frequency is caused by the mass-spring system composed of the baseplate and the railpad. The overall dynamic stiffness of WJ-7B fasteners is close to the dynamic stiffness of the railpad; and the deformation of the clip has little effect on the overall high-frequency dynamic stiffness of the fastener.
  • Liu Fei, Xu Shuhui, Wang Xiaoting, Wang Xinzhuo, Feng Mengyu
    Forging & Stamping Technology. 2023, 48(8): 176-184.
    In order to suppress the vibration in vertical direction of four-roll strip mill, firstly, considering the segmental nonlinear elastic force under the influence of dynamic clearance, the dynamic model of rolling mill roll system under the joint action of segmental nonlinear elastic force and dynamic rolling force was established, and the amplitude-frequency characteristic equation of the system was solved by using the average method. Then, the time-domain characteristics and frequency characteristics of the roll system when the elastic modulus of hydraulic oil changes were simulated with the actual parameters of rolling mill, and the influence laws on the vibration behavior of the roll system was obtained. Furthermore, the change laws of the amplitude-frequency response of the roll system under different hydraulic system parameter changes were compared, the influence of the hydraulic cylinder parameter change on the vibration behavior of the system was analyzed through the bifurcation characteristics, and the parameter interval was obtained when the system cycle was running stable.Finally, a state feedback controller was designed to realize the vibration control of the dynamic clearance rolling mill roll system. The analysis of amplitude-frequency characteristics and bifurcation characteristics shows that the controller can effectively weaken the influence of the dynamic clearance on the stability of rolling mill roll system, and suppress the chaotic behavior of the roll system, which provides a theoretical reference for suppressing the vibration of rolling mill roll system.
  • JIA Zhenyuan, FU Rao, WANG Fuji
    Journal of Mechanical Engineering. 2023, 59(19): 348-374.
    Carbon fiber reinforced polymer composites (CFRPs) have significant advantages in manufacturing various components of advanced equipment in the fields of aerospace, marine, energy, etc., due to their superior characteristics, including lightweight, high strength, and feasibility of integrated manufacturing to near net shape. Machining of CFRP components is one of the most critical processes for assembly and finally achieving equipment. However, CFRPs are featured with multi-phase, laminated and anisotropic nature, and the machining of CFRP components is prone to delamination and other defects, which would seriously affect their service performance and production efficiency. Therefore, high-quality and efficient machining of CFRP components has always been a hot and challenging topic for investigation. Researchers have conducted numerous academic and engineering studies from various perspectives and achieved fruitful theoretical and technical findings. This study reviewed the important research advances of machining technology for CFRP components, summarized the traditional/non-traditional machining methods and their adaptability, and elaborated the cutting theory, cutting tools, and machining process of CFRP in detail. The development history of CFRP cutting theory is first introduced at macro and micro scales, and the guidance for restraining CFRP drilling and milling defects is discussed. Then, the design concept of drilling and milling tools is analyzed in-depth, and the cutting tool developments from traditional tool geometry optimization to novel tool geometry evolution are summarized. The influencing mechanism of machining parameters, special machining trajectory, cooling process, etc., on machining quality are discussed. Finally, the future research trend of machining theory and technology has been prospected for CFRP, and the possible challenges and opportunities in new materials, unique structural characteristics, stability, and process control have been proposed.
  • Yuan Zhizhong, Wang Mengfei, Zhang Bocheng, Duan Xubin, Li Biaomin, Yang Haifeng, Luo Rui, Cheng Xiaonong
    Heat Treatment of Metals. 2023, 48(9): 1-7.
    SKD11 steel plate after hot rolling and spheroidizing annealing was used. Two kinds of complex phase heat treatment processes, A-Q-A (Austempering-Quenching-Austempering) and Q-T-A (Quenching-Tempering-Austempering), as well asconventional Q-T(Quenching-Tempering) heat treatment process were carried out. The effect of heat treatment process on the microstructure, hardness and impact absorbed energy was studied. The results show that the microstructure of the specimens after A-Q-A and Q-T-A is the combination of lower bainite (LB) and martensite (M). The content of retained austenite is 13.2% and 18.6% for A-Q-A and Q-T-A, respectively. After A-Q-A, Q-T-A and conventional heat treatment Q-T, the hardness of the specimens is 58.5, 58.6 and 60.5 HRC and the impact absorbed energy is 31.3, 27.6 and 15 J, respectively. The excellent combination of strength and toughness of the SKD11 steel plate is realized by the duplex-phase heat treatments, which does a beneficial exploration in improving the toughness of the cold working die steel.
  • Kang Jialin, Xu Jiangli, Yao Chuan'an
    Forging & Stamping Technology. 2023, 48(7): 156-161,183.
    In order to improve the fault diagnosis ability of cold rolling mill, comprehensively using the noise reduction technology of Ensemble Empirical Mode Decomposition (EEMD) algorithm and Discrete Wavelet Transformation(DWT), a joint noise reduction technology by EEMD-DWT was designed, and it was ensured that the useful features were fully preserved under the premise of removing noise.Then, the smooth curve signal was obtained by using EEMD-DWT mode for denoising, which showed excellent denoising effect.The application signal results show that when denoising with EEMD-DWT, it includes obvious impact characteristics, which effectively reduces the noise component in the region where the amplitude is near zero, and ensures that the original vibration characteristics are effectively reserved when the noise is fully removed.When DWT or EEMD method is used alone for denoising, a large amount of effective information is lost.When the EEMD-DWT joint noise reduction method is used for processing, the ideal noise reduction effect is achieved, and the useful parameters contained in the signal are fully preserved.Thus, this research can accurately identify different fault degrees of cold rolling mill, which has good theoretical support significance for improving the fault diagnosis level of similar mechanical transmission equipment.
  • LI Zhong-shan, WANG Mei, HU Yao-bo, DAI Yuan-xiao
    Transactions of Materials and Heat Treatment. 2023, 44(7): 48-56.
    The Mg-0.7Sm-0.3Zr alloy ingots with a diameter of 80 mm were extruded into bars with a diameter of 16 mm at 350, 380 and 410℃ respectively. Microstructure, texture and mechanical properties of the Mg-0.7Sm-0.3Zr alloy extruded at different temperatures were studied by means of optical microscope(OM), scanning electron microscopy(SEM), electron backscatter diffraction(EBSD) technique and room temperature tensile test. The results show that the microstructure of the as-cast alloy is mainly α-Mg matrix with coarse grain size of 20.7 μm. The grains are obviously refined after extrusion, and the average grain size is 2.83 μm after extrusion at 410℃. There are many fine grain bands alternately distributed along the extrusion direction. With the increase of extrusion temperature, the recrystallization fraction increases gradually, the strength of the alloy decreases gradually, and the elongation increases gradually. The tensile strength, yield strength and elongation of the alloy extruded at 410℃ are 202 MPa, 144 MPa and 44.4% respectively.
  • HU Wen, DENG Zejian, ZHANG Bangji, CAO Dongpu, YANG Yanding, CAO Kai, LI Shen
    Journal of Mechanical Engineering. 2023, 59(12): 332-342.
    The lane-change safety and efficiency in the dense traffic will be greatly improved if the driver cooperativeness of the surrounding vehicles can be estimated for the autonomous heavy truck, which has inferior flexibility and dynamic stability, as well as greater destructiveness. Therefore, this study propose a lane-change decision-making and planning method based on the predicted driver cooperativeness of the surrounding vehicles and the asymmetrical risk assessment. The driver cooperativeness of the following vehicle in the target lane is estimated by considering the driving environment and the trajectories predicted by Gaussian mixture model, which is also used to construct the asymmetrical risk model. The utility theory is used to describe the probability of selecting the target lane, and then the driving decision will be made by combining the risk level of the target lane in the prediction horizon. Finally, a multi-objective cost function is designed to select the optimal trajectory from the candidates generated by the polynomial curve. The results of simulation using the naturalistic driving dataset show that the proposed method can accurately predict the driver cooperativeness and correctly recognize the risk level. Sequentially, the autonomous heavy truck can make the lane-change decision more safely and efficiently in the dense traffic.
  • ZHAO Zhibin, WANG Chenxi, ZHANG Xingwu, CHEN Xuefeng, LI Yinghong
    Journal of Mechanical Engineering. 2023, 59(19): 253-276.
    Laser powder bed fusion (LPBF) has gradually become a "potential stock" for fast, low-cost, high-performance, and short-cycle manufacturing of difficult-to-machine metal components. It is considered to be one of the most widely used metal additive manufacturing technologies, and has been widely used in aviation, aerospace and other industrial fields. However, the stability and consistency of additive manufacturing process and forming quality is a challenging problem for the industry and has become a "blocker" for LPBF to embrace the mass production. The current LPBF additive manufacturing monitoring system mainly focuses on "measuring", that is, measuring of various process information. Its quality evaluation and control technology are not mature enough, and intelligent monitoring combined with advanced sensing technology and artificial intelligence methods is expected to become a "sharp edge" for mass production of LPBF additive manufacturing. Following the trend, this paper summarizes the research progress and development status of intelligent monitoring in LPBF additive manufacturing from four aspects:LPBF defect types, process information perception, process quality intelligent evaluation, process parameter optimization and quality control. Some challenges in developing a mature intelligent monitoring system for mass production of LPBF additive manufacturing are pointed out. Finally, solutions and future prospects for addressing these challenges are discussed.
  • WANG Yuming, LI Hongliang, CHEN Liqing, LIU Jian, LIANG Xiutian
    Journal of Mechanical Engineering. 2023, 59(15): 151-161.
    In order for the transfer case in a short period time to undergo the full-range analysis of three stages of hydrodynamic lubrication, mixed friction and rough contact, the hydrodynamic lubrication models with steady and dynamic elastic qualities as well as the mechanical models for compressional lubrication phase are to be established. Simulation results on the variation curves of oil film thickness, speed difference, viscous torque, rough torque and total torque are obtained by using the established torque transmission models. Based on the above simulation, the test bed of the transfer case is constructed. After the test and verification of the models, the influence of the groove width, the surface roughness, engaging pressure, the number of friction plates, the material permeability and the thickness of the friction plate on the torque transmission process is studied by using the models. The results show that the groove width mainly affects the torque transmission of the transfer case through the viscous torque. The roughness ratio of different surfaces of the friction plate is in direct proportion to the time ratio of the achieved rough torque, while the engaging pressure mainly influences the torque transmission of friction plate through rough torque, and the engaging pressure of friction plate is in direct proportion to the rough torque transmitted by the friction plate in the process of operation.
  • ZHAO Sijie, YI Chuanming, XIAO Gang, DAI Luyi, ZHANG Ning, WAN Keqian, YANG Qinwen
    China Foundry Machinery & Technology. 2023, 58(5): 33-38.
    With the rapid development of the digital economy, the integration of additive manufacturing and digital twin technologies is an inevitable trend in the digital transformation of high-end manufacturing industry, which has attracted attention from all sectors of society.The origin, definition, and key technologies of additive manufacturing and digital twin technology have been summarized in the text.The system framework and application status of digital twin technology in the field of additive manufacturing have been analyzed.A system technology architecture based on the development of additive manufacturing digital twin products and their industry application requirements have been proposed.The key research directions and key technologies have been elaborated.The development trend and application prospects of additive manufacturing digital twin technology have been explored.This study provides innovative ideas for promoting the integration technology research of digital twins and additive manufacturing, as well as the development of applied products.
  • Plant Maintenance Engineering. 2023, 0(14): 169-171.
  • Zhang Kaifa, Yun Pengfei, Li Jiajia, Liu Hua, Yi Ke, Wang Chaonan, Li Wei
    Special Casting & Nonferrous Alloys. 2023, 43(9): 1291-1296.
    Fe distribution and macrostructure of SP700 ingot melted by vacuum arc remelting under different processes were analyzed comparatively. The results indicate that Fe in the titanium alloy presents an obvious positive segregation trend. Fe content in the core of the ingot riser is 2.38%, and cross-section range is 0.58%, while that in the core of the ingot bottom is 1.90%, and the cross-section range is 0.23%. Fe content is increased along the solidification direction and aggregate in the core and head of the ingot. The uniformity of Fe element in the electrode block is improved by adjusting the process route and selecting the appropriate intermediate alloy and distribution method. Meanwhile, Fe segregation is effectively inhibited by taking melting parameters such as strong cooling boundary, 1 000 melting current, strong stirring intensity, and long feeding time. After optimization, the composition distribution of the ingot is more uniform, and Fe content in the center of the riser is 2.03% with cross-section range of 0.21%. The grain size is reduced with homogeneous structure, and Fe segregation in the equiaxed crystal region is weakened.
  • LI Linxiang, HUANG Yanfei, XING Zhiguo, LI Zhixiong, WANG Haidou
    China Surface Engineering. 2023, 36(3): 1-21.
    Ultrafast laser texturing is a new surface processing method that uses ultrashort pulse laser technologies such as picosecond and femtosecond lasers to prepare finer texture structures based on reducing heat source damage on the surface of materials. With the development and application of bionics, the surface structure features of animals and plants have been gradually applied to the surface of materials, and surface properties such as wear resistance, anticorrosion, defrosting, antireflection, and antifouling have been obtained. However, biomimetic textures are processed by long pulse lasers. The surface is significantly affected by heat, and the texture size cannot be refined. Therefore, ultrafast laser preparation of biomimetic textures has been adopted because it can realize refined design and processing of textures and greatly improve the reproduction accuracy of biomimetic textures. Moreover, it enhances the mechanical properties of the material surface and provides better surface quality. At present, biomimetic targets for the preparation of biomimetic textures using ultrafast lasers are gradually expanding from shark skins and lotus leaves to carapaces, moth eyes, feathers, and other biological structures with surface properties. The main texture types are micro-nano composites, array geometries, and random textures. Using ultrafast lasers, a series of biomimetic texture performance studies and optimizations have been performed to explore the ablation mechanisms of different materials. In this paper, the research progress of ultrafast laser biomimetic texture is reviewed in terms of the three properties of wear resistance, wetting, and antireflection, and the processing principle of ultrafast lasers is introduced. Ultrafast lasers enable energy deposition to occur at a solid density and ultrashort pulse width, change the interaction mechanism between the laser and matter, and effectively reduce thermal effects. The ablation thresholds of different materials are summarized in this paper. Through the study of biomimetic textures such as the composite micro-convex structure of lotus leaves, accompanying wave and convex structure of insects, and ridged-scale structure on the surface of reptiles and shark skin, it was found that the density of the texture surface and direction of friction convergence are important factors affecting the frictional behavior of textures. By controlling the texture parameters, ultrafast laser biomimetic textures can reduce the friction coefficient of most metals by 20-40%. Through superhydrophobic structures such as bionic rose petals and mosquito compound eyes,the contact angle of the material surface can reach a superhydrophobic state of more than 150°, which effectively improves the anticorrosion, microchannel, and antifrost performance. In general, micropillar arrays with small diameters, dense spacings, and large depths exhibit better hydrophobic effects. However, the influence of the laser on the material surface increases its chemical polarity,leading to hydrophilicity. However, with the adsorption of carbon atoms and organic matter, the nonpolar bonds on the material surface increase, resulting in a decrease in the free energy of the material surface and causing the occurrence of the wettability transition phenomenon. Therefore, the wettability of a laser-machined surface can be changed by controlling the free energy of the material surface. Femtosecond lasers can be used to fabricate micro-to nanostructures on silicon thin films, improving their light-harvesting capabilities. Changing the laser processing medium can further increase the texture density and significantly reduce the reflectivity. Additionally, other elements can be doped into the material surface under the action of pulsed radiation, thereby further improving the antireflection performance of materials. In summary, the technology of biomimetic texture preparation using ultrafast lasers is gradually being applied in many fields such as machinery, medical treatment, aviation, and infrared detection. Using ultrafast lasers to fabricate biomimetic textures to realize and optimize various functional surfaces has become a current research hotspot. Finally, this paper summarizes the basic principles of ultrafast laser processing and comprehensively discusses the sources of biomimetic designs for three types of textures, including wear resistance, wetting,and antireflection, as well as the design and processing methods of the parameters for the three types of textures in different application environments. The action mechanism and principle of ultrafast laser biomimetic texture are analyzed. Furthermore,the ultrafast laser processing of biomimetic texture is comprehensively described and the development direction of ultrafast laser biomimetic texture preparation is provided.
  • ZUO Wenhao, CHEN Kuisheng, ZHAN Congchang, TU Fuquan, WU Lin
    Machine Tool & Hydraulics. 2023, 51(14): 182-187.
    For the multi-way directional valve,excessive steady-state flow power will cause the spool clamping and the operability of the directional valve to decrease.Base on AMESim and Fluent co-simulation,it is found that the peak of steady-state flow power usually occurs when the valve opening is small,tending to close the valve port;steady-state flow force accounts for 25.12% of the maximum operating force in reset process of spool valve;under the influence of steady-state flow force,the spool will obtain too large control force,which destroys the linear relationship between spool stroke and the reset spring force.Aiming at this situation,based on flow passage reconstruction method and special valve cavity method,a steady-state hydraulic power compensation method was proposed for spool valve,which was to set a kind of baffle boss on the valve core.The flow field simulation results of the improved spool show that the larger the diameter of the baffle boss is,the more obvious the effect of reducing the steady-state hydraulic force is,which can be reduced by 65.18% at most;however,too large diameter of the baffle will change the pressure characteristics of the multi-way directional valve,which makes the improvement effect not ideal.
  • ZHANG Zeyu, HUI Jizhuang, ZHANG Haobo, GENG Qi, BU Zhengfeng
    Journal of Mechanical Engineering. 2023, 59(16): 300-314.
    In order to avoid energy waste due to excess power of the loader transmission system, or insufficient power to affect the performance, a power matching method for the primary and secondary working conditions of the engine and the hydraulic torque converter is proposed. Based on the V-type working condition of the loader, the throttle signal, gear signal and brake signal are used as the basis for dividing the 6-segment cycle working condition, and it is subdivided into 11 working condition segments, which are further divided. It is classified into four traction stages: shoveling, lifting, starting, and constant speed. Combining the primary and secondary working conditions of the loader at different cycle stages, the power matching study of the engine and the torque converter is carried out. Using the method of primary and secondary conditions to analyze the power of the hydraulic system and the throttle opening of the engine in different traction stages, and combined with the common working characteristics of the engine and hydraulic torque converter, it is concluded that the engine almost works at the rated power point in the digging and lifting stage. Overloading shall be avoided as far as possible; during the starting and constant speed phases, the output torque point of the engine is relatively low,has the ability to withstand partial load fluctuations, and works as far as possible in the economic fuel range. Furthermore, the model of loader is constructed to compare and verify the primary and secondary working conditions with the variable power control of engine. The analysis method of primary and secondary working conditions of construction machinery based on box diagrams and the classification method of traction working conditions of loaders lay the foundation for the power matching of engine and hydraulic torque converter under different working conditions, and also for the vehicle transmission system. Performance optimization provides a reference.
  • WU Yuezhong, ZHANG Ting, FEI Minghao, WU Denghao, REN Yun
    Journal of Mechanical Engineering. 2023, 59(13): 280-289.
    Centrifugal pumps are widely used in various fields of industrial production, and they account for 22% of the industrial electricity consumption. A new sensorless online monitoring technology is proposed to achieve effective monitoring of energy consumption of centrifugal pump units by replacing the sensor monitoring methods due to high cost and high failure rate. On the basis of a standard flow rate Q and shaft power P (QP) prediction model, a multistage centrifugal pump driven by an asynchronous motor is tested in lab to obtain performance data under different operating conditions. The centrifugal pump characteristic curves at the different speeds are modified to regular speeds by using the affinity law. A predictive mathematical model of flow rate versus power and speed, and head versus flow rate and speed is developed. An improved QP model with speed difference weighting algorithm is proposed based on the results of flow and head error analysis at different speeds, and carried out error analysis on the flow rate and head estimation models with four typical weighting functions. Results showed that the improved QP model with weight function III has the smallest average prediction errors, its flow rate relative error is 3.66% and head relative error is 1.51%. The prediction accuracy is significantly improved compared with the standard QP model. The improved QP estimation model not only improves the prediction accuracy of centrifugal pump operation status, but also provides a theoretical basis for the development of senseless online monitoring technology of centrifugal pump.
  • XU Si-nuo, FENG Ying-hao, WANG Chun-hui, QIAN Ling-yun, SUN Chao-yang, FENG Shao-chuan
    Journal of Plasticity Engineering. 2023, 30(6): 67-87.
    Compared with the traditional metal plastic forming methods,ultrasonic vibration assisted technology based on Blaha effect can reduce the forming load effectively and improve the formability and surface quality of materials. After more than half a century of the development,ultrasonic vibration assisted technology has become an advanced metal plastic forming method with broad prospects,especially provides a feasible way for the plastic process of high-performance difficult-to-deform alloys. The research progress of ultrasonic vibration assisted acoustic effect mechanism including acoustic softening effect and acoustic residual hardening effect was introduced,and the constitutive model building and numerical simulation research results based on acoustic effect mechanism were presented,and the application status of ultrasonic vibration assisted drawing,punching,extruding and cutting was reviewed. The main deficiencies in the mechanism analysis and application study of ultrasonic vibration assisted forming at present were expounded,the research emphases and development trends of related problems were discussed and prospected.