Table of Content

10 June 2022, Volume 33 Issue 11

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Dimensional Parameter Optimization of Planar Closed-loop Legged Mechanisms

WANG Xianye, LIU Haitao, HUANG Tian

2022, 33(11):  1261-1268.  DOI: 10.3969/j.issn.1004-132X.2022.11.001

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Aiming at the foot trajectory outputs by Theo Jansens linkages, the dimensional parameters of a novel planar closed-loop legged mechanism were optimized. The kinematic models of the mechanism were derived using the Assur groups methods. According to the structural characteristics, the number of design variables was reduced to one by using the position limitation of a crank-rocker mechanism. A single-objective optimization problem was established by minimizing the minimal deviation of the foot trajectories of two mechanisms subjected to the geometric constraints of the dimensional parameters. This problem was solved by the one-dimensional search method, leading to the design and fabrication of an eight-leg mobile robot. The feasibility of the design was verified by experimental results.

Reliability Analysis of Machining Accuracy and Processing Parameter Optimization for Thin-plate Parts

YI Qian, LI Congbo, PAN Jian, ZHANG You

2022, 33(11):  1269-1277.  DOI: 10.3969/j.issn.1004-132X.2022.11.002

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To address the problems of low machining accuracy caused by cutting deformations during the machining processes of the thin-plate parts, a machining deformation prediction model was established by using the finite element method and Gaussian process regression algorithm. Then, the workpiece processing deformations and machine tool motion errors were considered comprehensively to analyze the reliability of the thin-plate machining accuracy. A milling process parameter optimization design model was established with machining efficiency and average machining deformation as the goal, and the machining accuracy reliability as the constraint. The multi-objective optimization algorithm was used to solve the model, determining the optimal combination of processing parameters for coordinated processing efficiency and processing deformations. The case study indicates that after the optimized design, the minimum machining accuracy reliability reaches 98.21%, the average machining deformations are reduced by 21.14%, and the machining efficiency is increased by 4.18%. A feasible method is provided for the selection of milling process parameters for thin plate parts.

Study on Effects of Tooth Root Transition Arc on Grinding Temperature and Residual Stress during Full Tooth Groove Profile Grinding

YI Jun , GONG Zhifeng, YI Tao, ZHOU Wei,

2022, 33(11):  1278-1286.  DOI: 10.3969/j.issn.1004-132X.2022.11.0003

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A three-dimensional FE (finite element) simulation model of the grinding temperature field was proposed by considering the coupling effects of three adjacent heat sources（tooth bottom heat source， transition arc heat source and tooth profile heat source）to calculate the grinding temperature in profile grinding of full tooth grooves. Then， the residual stresses caused by grinding were calculated by the FE method based on thermal structure coupling. The characteristics of the grinding temperature and residual stress fields were analyzed， as well as the influences of the size of the tooth root transition arcs on the grinding temperature and the residual stress distribution at the tooth root after grinding. The results show that the effects of the transition arc radius on the grinding temperature are relatively small， but the effects on the residual stress are relatively large. Compared with a tooth groove without transition arcs， the maximum residual stress after grinding is reduced by more than 20% when the radius of the transition arcs exceeds 2 mm. The measurement results are consistent with the FE simulation ones， which proves the correctness of the simulation results. 

Study and Optimization of Energy Storage Hydraulic Cylinders Synergistically Driving Heavy Manipulator Systems

JIN Chao, QUAN Long, XIA Lianpeng, GE Lei, ZHAO Bin

2022, 33(11):  1287-1293,1301.  DOI: 10.3969/j.issn.1004-132X.2022.11.004

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Aiming at the method of using energy storage hydraulic cylinders to coordinate the lifting of the heavy manipulators to realize the gravitational potential energy recovery and utilization, the impacts of the different area ratios of the rodless cavity for the energy storage cylinders and the driving cylinders on the energy saving effectiveness of the systems were studied. The working principles of the energy storage cylinder cooperative driving circuits were analyzed to control the boom up and down, and the mathematical system model was established. Taking a 76 t hydraulic excavator as an example, a multi-disciplinary co-simulation model of the whole machine was constructed in Simulation X, and the accuracy of the model was verified by tests. According to this model, the system energy consumption characteristics of hydraulic excavators were optimized and simulated for the area ratio of the rodless cavity for the energy storage cylinders and the driving cylinders under no-load and loaded conditions. The simulation results show that: in the same working cycle, the output energy of the hydraulic pump of the optimized energy storage cylinder cooperative drive system is about 732.0 kJ, which saves about 253.8 kJ compared with the energy before improvement, and the energy saving rate is increased from 27.2% to 46%, realizing the improvement of energy-saving effectiveness. 

High Temperature Mechanics Modeling and Experimental Research of Metal Rubber Coated Damping Structure

ZI Bao, DING Zheyu, WU Yiwan, BAI Hongbai

2022, 33(11):  1294-1301.  DOI: 10.3969/j.issn.1004-132X.2022.11.005

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 Aiming at the vibration reduction problems of pipeline systems under high temperature， a high temperature mechanics model of the metal rubber coated damping structure of the pipelines was established by equivalent linearization method. The model was used for analyzing the stiffness and response amplitude of metal rubber treated with different temperatures. The thermal-vibration joint test system of the pipelines was set up firstly. Then the damping performance of the coated damping structure of the pipelines was verified with different ambient temperatures and metal rubber densities， where the insertion loss was taken as the evaluation index. The results show that reducing the density of metal rubber may effectively increase the vibration attenuation effectiveness of the pipelines. At the same time， the effect of the ambient temperature on the metal rubber coated damping structure is negligible， indicating that the coated damping structure may work well in a high temperature environment. 

Design and Experimental Study of Piezoelectric Actuated Micro Precision Clamping Mechanisms

LI Chong, TONG Yujian, LIANG Kang, ZHONG Wei, FANG Jiwen

2022, 33(11):  1302-1308,1385.  DOI: 10.3969/j.issn.1004-132X.2022.11.006

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In order to simplify the structure of precision piezoelectric clamping mechanisms and reduce the manufacturing difficulty， a micro precision piezoelectric clamping mechanism was proposed based on flexible hinge and two clamping arms， and the working principle was analyzed. The output displacement and force model of the precision piezoelectric clamping mechanisms were established based on the nonlinear strain relation of piezoelectric materials， and the output characteristics of the precision piezoelectric clamping mechanisms were analyzed by numerical simulation. The output performance of the precision piezoelectric clamping mechanisms and the correctness of the theoretical model were verified by the experimental results. The results show that both of the experimental and simulation displacements of the two clamping arms is as hysteretic. The maximum radial displacements of the two clamping arms are as 73.8 μm and 68.6 μm at 120 V driving voltage， respectively. When the driving voltage is greater than 50 V， the output displacement errors of the two clamping arms are within 10% between the experimental values and simulation ones. When the driving voltage is as 120 V， the experimental values of the maximum tangential and axial clamping forces of the clamping mechanisms are as 7.8 N and 5.7 N， respectively. 

Study on Motion Characteristics of Double Push Rod Manipulators with Joint Clearances

ZHAO Fuqiang, LI Zhaoyu, GAO Zhiying, WU Hongqing, NIU Zhigang

2022, 33(11):  1309-1316.  DOI: 10.3969/j.issn.1004-132X.2022.11.007

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A mathematical model of the joint clearances and the kinematic model of the double push rod manipulators with joint clearances were established. The influences of the position and number of three different joint clearances including single joint clearance A, single joint clearance B, double joint clearance A and B on the trajectory, velocity and acceleration of the ends of the manipulators were analyzed by using simulation, and the absolute errors were used as the evaluation index to quantitatively analyze the influence degree. An experimental platform was built to verify the simulation results. The results show that, joint clearances lead to errors in the X-axis and Y-axis directions of the end motion trajectories of the manipulators, and the track errors caused by double joint clearance A and B are approximately the sum of the track errors of two single joint clearances. The velocity and acceleration curves at the ends of the manipulators are pulse fluctuations due to the existence of clearances. The influence degree of single joint clearances A and single joint clearances B on the curve is similar, and the influence degree of double joint clearances A and B on the curve under coupling is much greater than that of single joint clearances.

IAFSA for Solving Inverse Kinematics of Redundant Robotic Spraying System

LIU Xuemei, FENG Yan, YANG Zhen, LI Aiping, LU Junguo

2022, 33(11):  1317-1323.  DOI: 10.3969/j.issn.1004-132X.2022.11.008

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In order to solve the inverse kinematics problems of a redundant robotic spraying system for ship segments, the modified DH method was used to establish the kinematics model of the robotic systems. An optimization model for inverse kinematics of redundant robots was established to minimize position errors, posture errors and joint travels, and an IAFSA was proposed to solve the model. The dynamic adjustment strategy of visual ranges and step size based on normal distribution was introduced to enhance the precision of the solutions and reduce the computation time, improving the overall performance of the algorithm. Compared with artificial fish swarm algorithm and hybrid IAFSA, the experimental results show that IAFSA possesses stronger search ability, faster convergence speed and relatively less computation time. The high accuracy of the solutions and good stability of the errors were verified in the SolidWorks Motion simulations, which demonstrates the effectiveness of IAFSA in solving the inverse kinematics problems of redundant robots.

Intelligent Fault Diagnosis Method for Rotating Equipment Based on Full Vector Enhanced Deep Forest

JIANG Wanlu, LI Man, ZHANG Peiyao, ZHAO Yapeng, ZHANG Shuqing

2022, 33(11):  1324-1335.  DOI: 10.3969/j.issn.1004-132X.2022.11.009

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A new fault diagnosis method for rotating equipment was proposed based on deep forest improved by full vector data fusion to solve the problems that traditional intelligent diagnostic methods required expert knowledge and complex feature extraction, deep neural network model had complex structure and was difficult to construct, and the single-channel signals were incompleteness. According to the characteristics of vibration signals of rotating equipment, the full vector data fusion technology was combined with multi-grained scanning of deep forest to receive the homologous double-channel signals, so as to enhance the completeness of data. At the same time, the cascade layer of deep forest was improved to reduce the deep feature disappearance and feature redundancy. In order to verify the effectiveness of the proposed method, two fault diagnosis experiments of rolling bearing and axial plunger pump were carried out respectively. The results show that this method achieves a good diagnostic effectiveness on different rotating equipment and end-to-end fault diagnosis may be realized. In addition, it is also very excellent in fault recognition accuracy on small training data sets.

Improved SA-MEMD with Applications to Fault Diagnosis of Rolling Bearings

WU Lifeng, , LYU Yong, YUAN Rui, ZHU Xi, YOU Jun,

2022, 33(11):  1336-1344.  DOI: 10.3969/j.issn.1004-132X.2022.11.010

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The SA-MEMD algorithm reduced mode mixing by adding a sine assisted signal to an additional channel, but the algorithm was sensitive to noises, and the main frequency ratio of the auxiliary signals needed to be determined empirically. For this reason, an improved SA-MEMD was proposed. First, The non-local mean noise reduction was used to preprocess the original signals to reduce noise interference for the algorithm, then the short-time Fourier transform was used to determine the signal spectrum range, thus the optimal main frequency ratio was selected based on the minimum ensemble EMD energy entropy criterion. The steps of the SA-MEMD algorithm were used to complete signal processing. The analysis of simulation signals and actual signals proves that the improved method may alleviate the mode mixing phenomenon that exists in the traditional multivariate empirical mode decomposition methods.

Comparison of Corrosion Properties of SPFC440 Steel /5052 Aluminum Self-piercing Riveting Joints and Adhesive Bond-riveted Hybrid Joints

HUANG Zhichao, HU Zhaoxiao, LIU Shuaihong, LIN Yongcheng, JIANG Yuqiang, ZHOU Zejie

2022, 33(11):  1345-1352.  DOI: 10.3969/j.issn.1004-132X.2022.11.011

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The corrosion properties of SPFC440 steel and 5052 aluminum alloy self-piercing riveting joints were studied, and the self-piercing riveting joints and adhesive bond-riveted hybrid joints were fabricated respectively. The fatigue tests of joints with different corrosion durations were carried out, and the effects of adhesive on the corrosion and fatigue properties of riveting joints were analyzed. In addition, the fatigue fracture and crack extension were analyzed by SEM and EDS. The results show that the adhesive increases the strength of riveting joints and protects the metal interface and reduces the galvanic corrosion. The maximum static loads of adhesive bond-riveted hybrid joints are decreased continuously with the increase of corrosion durations. And the maximum static loads of self-piercing riveting joints are first increased and then decreased with the increase of corrosion durations. The tensile failure mode of adhesive bond-riveted hybrid joints is similar to that of self-piercing riveting joints. The fatigue cracks of self-piercing riveting joints are mainly concentrated in the regions of the locked sheet around the rivet. Failure mode of adhesive bond-riveted hybrid joints shows the fracture of the locked sheets. Serious fretting wear exists in the contact areas between the rivet and the locked sheet, and the contact surfaces between the pierced sheet and the locked sheet.

Research on Stability and Roundness Adaptive Control Method of Radial and Axial Ring Rolling Processes of Super Large Rings

NING Xiangjin, WANG Xiaokai, HUA Lin, HAN Xinghui, ZHANG Ke,

2022, 33(11):  1353-1360.  DOI: 10.3969/j.issn.1004-132X.2022.11.012

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In the radial and axial rolling processes of super large rings, such abnormal conditions as instability and loss of roundness often led to rolling termination and quality fluctuation. An adaptive control method of stability and roundness of ring rolling processes was proposed, and the experience of manual control was summarized from historical data. The stability control method of ring rolling was established based on fuzzy adjustment of cone roll revolution speed, and the roundness control strategy of ring rolling was developed based on the guide force feedback. Using ABAQUS software and subroutines, the adaptive control subroutines of ring rolling processes were designed, and finite element models of adaptive control of 16 m super large ring rolling processes were established. The rings offset and roundness error change rules were analyzed during ring rolling processes in different methods of cone roller revolution speed fuzzy adjustment, guide force feedback and cone roller revolution speed fuzzy adjusting integrated guidance force feedback comprehensive control. The results show that, with regard to the control method, the rings offset is reduced by 48.3% and the roundness errors are reduced by 61.8% compared with the conventional control methods.

Active Suspension System Energy Consumption and Engine Power Matching Control for Emergency Rescue Vehicles

ZHU Jianxu, ZHAO Dingxuan, , GONG Mingde, CHEN Hao, , YANG Mengke,

2022, 33(11):  1361-1368.  DOI: 10.3969/j.issn.1004-132X.2022.11.013

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Due to the mismatch between the active suspension system energy consumption and the engine power thus causing the fluctuations of pressure and flow in the hydraulic active suspension systems, and the engine over loaded even flameout, an active suspension system energy consumption and engine power matching control schemes was proposed herein. The conditions of ensuring stable operations of the engine and the active suspension systems were analyzed. In order to make the maximum power of the active suspension system less than the residual power of the engine in the current states, a control strategy of compensate the variable pump discharge control signals was proposed according to the average flow consumed by the active suspension systems. The fuzzy PID control methods were applied to design the power matching controller. The test results show that compared with the original active suspension systems, the average power consumption of the active suspension systems appied the proposed control schemes is reduced by 42%, the average torque percentage is reduced by 39.6%. The energy consumption of the active suspension systems and engine load are significantly reduced.

Research on Fracture Mechanism and Tests of Wheel Flange Lubrication Device Hangers for Metro Vehicles

ZHANG Ming, ZHI Pengpeng, HUO Wenbiao, LI Zhiyong

2022, 33(11):  1369-1376.  DOI: 10.3969/j.issn.1004-132X.2022.11.014

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Aiming at the fracture problems of the wheel flange lubrication device hangers during the service of metro vehicles, the fracture mechanism was studied by a method of combining material and dynamic stress tests with finite element simulation, and a new structural design scheme was proposed. Firstly, through the comprehensive analysis and characterization of the micro/macro fractures of the hanger, the mechanism causes of fatigue fractures were determined from the material point of view. Secondly, combined with dynamic stress tests and cumulative damage theory, the fatigue damage values at the key positions of the hanger fractures were calculated, and the structural causes of hanger fractures were determined from the perspective of line tests. Thirdly, the finite element model of the hangers was established, and the static and fatigue strength simulations were performed based on EN13749 standard. The rationality of the structural design was judged from the theoretical point of view, and compared with the results of material and line test analyses. Finally, the improvement scheme of hanger structure was proposed and verified by simulation and dynamic stress tests. The results show that the hanger fractures are due to low stress and high cycle fatigue, the source of fatigue is located inside the stiffener fillet weld, and the cumulative damage values and material utilization rates of the stiffener fillet weld are both greater than 1. The main cause of the hanger fractures is that the stiffener fillet weld bears frequent alternating loads due to unreasonable structure, and have unfazed defects. The welding quality is improved by changing the structures and materials of hangers, and the standard requirements of on-line operations for the flange lubrication devices are met.

Study on Wave Suppression Mechanism of Porous Baffles in Vehicle Fuel Tanks under Variable Conditions

SUN Chuanbin, SHEN Minmin, TONG Baohong, HUANG Hu, ZHANG Kun

2022, 33(11):  1377-1385.  DOI: 10.3969/j.issn.1004-132X.2022.11.015

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The fuel would shake violently, and interrupt the supply, or even the fuel tank structure would be damaged in variable acceleration. The fuel sloshing process was analyzed from numerical values and experiments based on the numerical simulation of dynamic grid coupled VOF, and built a horizontal excitation test platform. Taking porous baffles in the tank of a heavy-duty commercial vehicle for example, the baffles were systematically analyzed to suppress fuel sloshing and the wave suppression mechanism was discussed by porous baffles. Studies show that the porous baffle may reduce the wall pressure, the free liquid surface height and the liquid surface profile fluctuation. The transient local high pressure appears on the baffle walls during the movement of the fuel tanks, but the fatigue damage against the baffle structure is low. The pores of the baffle divide the small part of the fluid into multiple jets, which sharply slows down the transmission of the traveling wave. The flow field near the porous baffle produces vortex which accumulate and dissipate energy, and reduce the fluids velocity. It may achieve the purpose of restraining the violent shaking.