China Mechanical Engineering

Integrated Vehicle Chassis Nonlinear Robust Constrained Optimization Control Based on Dissipative Theory

ZHANG Jiaxu, ZHAO Jian, SHI Zhengtang, YANG Xiong

2021, 32(08): 883-889. DOI: 10.3969/j.issn.1004-132X.2021.08.001

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A nonlinear robust controller for integrated control of active front wheel steering subsystem and direct yaw moment control subsystem was presented based on dissipative theory. Firstly, an integrated vehicle chassis control model including body lateral and yaw motion degrees of freedom was established, and the un-modeled dynamics and the measurement errors both of the model parameters and feedback signals were regarding as the additive and multiplicative uncertainties of the system. Secondly, an integrated vehicle chassis nonlinear L2-gain control law was designed based on dissipative theory to suppress the effect of the additive uncertainties on the system performance, and an adaptive law was designed based on projection correction method to estimate and compensate the multiplicative uncertainties. Thirdly, the sequential quadratic programming method was used to realize the constrained optimal allocation of the corrected yaw moment, which was the output of the proposed integrated vehicle chassis nonlinear L2-gain control law. Finally, the feasibility and effectiveness of the proposed integrated vehicle chassis nonlinear robust controller were verified via vehicle dynamics simulation software.

Prediction of Cutting Forces for Chamfered Inserts Based on Modified Slip-line Field Model#br#

ZHUANG Kejia, HU Cheng, DAI Xing, PU Donglin, DING Han

2021, 32(08): 890-906. DOI: 10.3969/j.issn.1004-132X.2021.08.002

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Based on the material plasticity slip-line theory and flow state analysis ahead of tool edge, a modified slip-line field model was proposed considering material stagnation zone (dead metal zone), and pre-cut region in negative-rake-angle cutting processes with chamfered insert. Furthermore, an iterative sollution to material shear flow stress and edge front cutting geometry was suggested. The relationships of chamfered edge geometry and slip-line field geometry were disclosed. An analytical approach to the orthogonal cutting force prediction method was developed by applying the presented model to the cutting processes with chamfered insert. Verifications including finite element simulations and orthogonal cutting trials were carried out for the modified slip-line field model and prediction method of cutting forces. Average errors are all less than 10% in comparisons of predictions and simulations as well as measurements. Results provide references for investigating the influences of edge geometries on material flow characteristics and tool cutting performances.

Dynamics Characteristics of Rotor Systems under Magnetic Bearing Excitation

LI Shengyuan, ZHENG Longxi

2021, 32(08): 901-907. DOI: 10.3969/j.issn.1004-132X.2021.08.003

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To analyze the vibration mechanism of the rotor systems excited by magnetic bearings, a calculation model for dynamics characteristics of a double-disk rotor system was established by using one-dimensional finite element method. The dynamics behaviors of rotor system under different types of magnetic bearing excitations were studied. Results show that the co-rotating sweep frequency exciting forces excite forward whirl mode of the rotor systems, while the counter-rotating sweep frequency exciting forces excite backward whirl mode. In both cases, the rotor system whirls in a circular trajectory. The unidirectional harmonic exciting force may be decomposed into the sum of co-rotating and counter-rotating exciting forces, therefore both of the backward whirl and forward whirl modes of the rotor system are excited and the rotor system whirls with an elliptical trajectory under the effect of unidirectional harmonic sweep exciting force. Under bi-directional harmonic sweep exciting forces, the whirl direction and whirl trajectory of the rotor system depend on the phase difference of the two exciting forces. Research results provide a theoretical basis for the selection of excitation scheme of magnetic bearings when evaluating the stability of rotor systems of high-pressure compressor.

Design and Mechanics Analytical Modeling of Vertical Multistage Displacement Amplification Mechanisms

LIN Chao, SHEN Zhonglei, LI Pingyang, ZHENG Shan

2021, 32(08): 908-915，937. DOI: 10.3969/j.issn.1004-132X.2021.08.004

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Piezoelectric displacement amplification mechanisms were difficult to obtain large working strokes and high frequency bandwidth in vertical direction. Therefore, a new vertical multistage displacement amplification mechanism was proposed by integrating two compound rhombus-type mechanisms, two lever mechanisms and a rhombus-type mechanism. Analytical models of displacement amplification ratio and input/output stiffness were deduced by energy conservation method and elastic beam theory. The analytical model of natural frequency was derived based on Lagrange equation. The analytical model was verified by finite element method. The analytical model of displacement amplification ratio herein has a high prediction accuracy and may provide a reference for optimal design of vertical compliant stage with a large working stroke. After compared with several vertical displacement amplification mechanisms from references, the proposed vertical multistage displacement mechanism shows better static and dynamic performances, with a displacement amplification ratio of 43.29 and a relative high natural frequency of 561.28 Hz.

Reduced Basis Analysis Method for Static Response Characteristics of Parametric Structures#br#

ZHANG Zheng,

2021, 32(08): 916-920. DOI: 10.3969/j.issn.1004-132X.2021.08.005

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A reduced-basis analysis method was proposed for efficiently solving the sensitivity extremum problems of parametric structures. A continuous mapping relationship between the parameter domain and the static response set was established by reduced-basis equilibrium equation, and then the structural parameter sensitivity of the static response was analyzed in reduced-basis spaces. The corresponding reduced-basis extremum model in the global parameter domain was established based on the parameter sensitivity formula. The global domain sensitivity extremum and the Pareto front for parametric structures could be rapidly acquired online by solving the reduced-basis extremum model, where the scale was already reduced. The method herein shows good feasibility through the solution and demonstration of numerical examples of structures.

Stochastic Statistical Energy Method for High-frequency Analysis of Uncertain Acoustic-Structural Coupling Model#br#

HAO Yaodong, GU Cansong, ZHOU Huanyang, DONG Junhong, LI Hongliang, DENG Jianghua

2021, 32(08): 921-929. DOI: 10.3969/j.issn.1004-132X.2021.08.006

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In order to solve the uncertainty problems of vehicle statistical energy analysis, a stochastic uncertainty statistical energy method for vehicle acoustic-structural coupling model was proposed. In this method, structural and acoustic cavity material parameters were taken as uncertain variables. A statistical energy model of acoustic-structural coupling system was built. Both of damping loss factors and coupling loss factors were calculated. Their partial derivatives with respect to material parameters were analyzed. Based on the theory of stochastic algorithm, the formulas for calculating the mean and standard deviation of noise were derived under uncertain material parameters. The stochastic uncertain statistical energy method was applied to simple plate cavity model and car firewall cavity model respectively, and the noise fluctuation characteristics of the model were solved under uncertain conditions successfully.

Design of Wearable Rigid and Soft Combined Hand Rehabilitation Devices

LIU Dong, WANG Minghao, BI Cong, SHUI Shengcai, CONG Ming, DU Yu

2021, 32(08): 930-937. DOI: 10.3969/j.issn.1004-132X.2021.08.007

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Hand rehabilitation devices were used for hand function recovery treatment. Rigid devices were not flexible enough, poor fitting, and easy to cause secondary damage, and soft devices had small driving forces and the complex soft devices were not easy to make. In order to overcome the shortcomings of rigid devices and soft devices, a wearable hand rehabilitation device combining soft joints and rigid knuckles was proposed. Firstly, the biological structure of human hand was analyzed, the soft joint structure was designed and its bending characteristics were analyzed. The pneumatic finger actuator was designed based on rigid and soft combination, and finite element stress and deformation analyses were carried out. Then, the soft silicone joint mould and hand rehabilitation device were manufactured. Finally, the test platform for pneumatic finger actuators was built to test the bending characteristics and fingertip forces of the rigid and soft combined finger actuators, and hand rehabilitation devices were used to grab objects of different shapes. Results show that the designed wearable hand rehabilitation devices may realize the rehabilitation training of hand grasping and holding.

Flexible Job Shop AGV Fusion Scheduling Method Based on HGWOA

LI Xixing, YANG Daoming, LI Xin, WU Rui,

2021, 32(08): 938-950，986. DOI: 10.3969/j.issn.1004-132X.2021.08.008

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Considering the AGV only participated in loading-unloading and transport in production processes of flexible job shop scheduling problem, an integrated scheduling model was proposed to ensure the integrated optimization of AGV path planning and flexible job shop scheduling. Then a two-dimensional vector coding scheme was applied based on two sub-problems of process sequencing and machine selection, and an AGV arrangement strategy was proposed based on the principle of first service in the decoding processes. The whale optimization algorithm was discretized, and a variety of targeted population initialization strategies were designed. The crossover operations and mutation operations of genetic algorithm were introduced to improve global search capability of whale optimization algorithm. The local search algorithm was embedded to achieve the balance between global search and local search. Then, a HGWOA was built up to solve the fusion scheduling model. The performance of the algorithm was verified by classical test examples. The parameters of the algorithm were optimized by orthogonal tests. Results show that HGWOA may achieve better results in solving AGV fusion scheduling problem of flexible job shops.

Design and Master-Slave Control of Dexterous Hands with Five Fingers Based on Tendon-sheath Transmission#br#

YIN Meng, XU Zhigang, ZHAO Zhiliang, HAN Wei,

2021, 32(08): 951-959. DOI: 10.3969/j.issn.1004-132X.2021.08.009

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In order to make the dexterous hand more light and anthropomorphic, a 19 joints dexterous hand driven by steering engine through tendon-sheath transmission was designed. Firstly, the configuration of the dexterous hands was determined by referring to the human hand joints. Joint decoupling and drive postposition were realized using tendon-sheath transmission. Joint mechanisms and driving integration were designed separately. Then, a multi-fingers kinematic model of dexterous hands was established and the workspace was analyzed. The master-slave tracking control of grasping was realized based on the sensors and master-slave mapping algorithm. Finally, a prototype of dexterous hand was built, and the joint motion experiments and grasping control experiments were carried out. Experimental results show the feasibility of applying the tendon-sheath transmission to dexterous hands. The dexterous hands may grasp a variety of objects based on master-slave control.

Transition Mechanism and Law of Electrode Materials of ESD

XU Anyang, WANG Xiaoming, ZHU Sheng, HAN Guofeng, ZHAO Yang, GUO Yingchun

2021, 32(08): 960-966. DOI: 10.3969/j.issn.1004-132X.2021.08.010

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A rotating electrode ESD device was used to deposit 1 to 6 layers of copper alloy coating layer by layer on the surface of Q235 steel. The deposition thickness, transition topography, surface and cross-sectional topography of each layer were calculated and analyzed. The transition mechanism, topography and law of the electrode materials of ESD were studied. Results show that the mass variation curve of the workpiece is similar to that of the electrode. As the number of deposition layers increases, the mass variation decreases until it is stable. The deposition layers are formed by transitional deposition of molten mass topography(liquid, semi-solid).The electrode and the workpiece material penetrate each other at the interface between the deposition layer and the substrate, forming a transition layer with a thickness of about 20~30 μm. The dilution effect of the workpiece material on the deposition layer mainly occurs at the junction of transition material group, which has minimal influence on its interior, and reduces with the increasing of the number of deposition layers. The deposition layers are formed by the lamination and coating of multilayer electrode metarial. As the number of deposition layers increases, the utilization rate of discharge energy decreases, the thickness of single deposition decreases, the grinding and coating effect of the electrode on the deposited surface increases, and the deposition rate of electrode material decreases.

Study on Forming Processes for Laser Brazing of Multilayer Diamond Grains and Ni-Cr Alloy#br#

LI Shichun, ZHOU Zhenhong, MO Bin, DENG Zhaohui

2021, 32(08): 967-975. DOI: 10.3969/j.issn.1004-132X.2021.08.011

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In order to realize the layer-by-layer laser brazing of multilayer diamond abrasive particles， the multilayer laser brazing process of Ni-Cr alloy and diamond abrasive particles was studied systematically, from single channel scanning to single layer scanning and then to multilayer scanning. The brazing channel and layer of cross section shape characteristic parameters were extracted, the brazing layer section forming parameterized evaluations was carried out. Combined with the brazing layer surface morphology, the brazing layer composite forming characteristics was evaluated and discussed, the influence of brazing process parameters on forming was studied. The results show that the laser power and scanning speed are the important factors affecting brazing forming. They affect the degree of fusion of alloy powders, molten pool width, and further affect the dispersion state of diamond and performance that diamonds are infiltrated and wrapped by solders, finally affect the smoothness of the brazing layers. When the overlapping rate between channels is as 30%~40%, the brazing forming quality is better. In the reverse scanning strategy, the number of scanning channels is as 10, the fixed laser power is as 700 W, the scanning speed is as 15 mm/s, the spot diameter is as 1.5 mm, the overlapping rate is as 30%, the laser brazing of multilayer abrasives is realized, the filler metal to the diamond infiltration package is sufficient, the middle area of the brazing layer is smooth and continuous, the overall forming quality is good.

Analysis and Prediction of Working Performance of Shearer Spiral Drums under Coal Seam with Gangue#br#

ZHAO Lijuan, WANG Yadong , WANG Bin

2021, 32(08): 976-986. DOI: 10.3969/j.issn.1004-132X.2021.08.012

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Based on the interface technology of Pro/E and EDEM, a coupling model of drum and coal seam with gangue was established, and the cutting simulations were carried out. Single factor test method was used to analyze the influence trends of physical and mechanics properties of coal and rock mass, blade spiral angle, pick arrangement, shearer traction speed and drum speed on drum load, load fluctuation, cutting specific energy consumption and coal loading effectiveness. The maximum relative errors of cutting performance and coal loading effectiveness prediction of spiral drum are 3.12% and 3.26% respectively using GA-BP network. The stress magnitude and distribution of spiral drums with different structures under typical working conditions were analyzed based on Workbench, and then the preferred drums under different coal seam occurrence conditions were determined. The simulations using EDEM provide support for the optimization of structural and kinematic parameters of spiral drums under different coal seam occurrence conditions. The performance prediction using GA-BP network provides a more rapid and reliable technical mean for the selection and design of high-efficiency spiral drums.

Reaserch on Anti-rollover Model Predictive Control of Counterbalanced Forklift Trucks

XIA Guang, LI Jiacheng, TANG Xiwen, ZHANG Yang, CHEN Wuwei

2021, 32(08): 987-996. DOI: 10.3969/j.issn.1004-132X.2021.08.013

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In order to reduce the probability of forklift rollover when turning at high speed, a hydraulic support cylinder was designed as actuator to provide lateral support force for the forklift truck. Aiming at the problems of judging the safe region of forklift truck in the driving processes, the dividing strategy of forklift driving states was proposed based on zero moment point. Taking the relationships between lateral component of zero moment point and forklift support plane as dividing basis, and considering the change of forklift support plane in rollover processes, the forklift rollover processes were divided into 3 stages of safe run, danger controllable and critical rollover. In safe run stages, the cylinder didnt provide support force. In danger controllable stages, the model predictive control algorithm was used to adjust cylinder support force and forklift attitude. In critical rollover stages, the cylinder was controlled to provide the maximum support force for the body. This method took a 3-DOF forklift truck roll model as control object and as the basis of zero moment point calculation. Then an anti-roll controller was built in Matlab/Simulink to simulate under European standard working conditions and real vehicle tests were carried out. Therefore, the validity of the anti-rollover model predictive control was verified.

Multidisciplinary Optimization of Submersibles Based on Parametric Analysis of Main Body#br#

LIU Feng, ZHAO Yankai, YAO Jingzheng, WANG He

2021, 32(08): 997-1007. DOI: 10.3969/j.issn.1004-132X.2021.08.014

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In order to improve the comprehensive performance of submersibles, the discipline decomposition of submersibles was carried out based on the idea of multidisciplinary design optimization. The design parameters and data transfer relationships in the overall design model were determined. The secondary developments of ABAQUS software and STAR-CCM+software were carried out, and the structure discipline and boat shape discipline parametric analysis flows were designed, the main body parametric analyses were realized as well. A fourth order response surface model was used to establish the approximate model of boat shape discipline and structure discipline. The propulsion parameters were fitted, and the approximate model of the propulsion discipline was established. The mechanical electrical equipment discipline was treated as quantitation. Relationship among energy discipline, propulsion discipline and mechanical electrical equipment discipline was determined. Also, the analysis model of energy discipline was established. Based on the discipline analysis model, the system levels were analyzed. Then the sensitivity analyses of design variables were carried out. A multidisciplinary optimization model of the submersibles was established based on multidisciplinary feasible method, and the second generation of non dominated sorting genetic algorithm (NSGA-Ⅱ) was used to solve the problem. Results show that the optimization effectiveness of the selected scheme is obvious and the comprehensive performance of submersibles is improved.

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