China Mechanical Engineering

Evolution of Concept of Machine Composition from the 19th Century to Modern Time

ZHANG Ce, YANG Tingli, LIU Jianqin

2023, 34(10): 1135-1139. DOI: 10.3969/j.issn.1004-132X.2023.10.001

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With increasing of productivity and development of machines， the concept of “machine composition” also evolved. The requirements of modern society for machines were gradually increasing， and complex machines came from the transformation of traditional machines. Understanding the evolution of machines was a necessary process for the transformation of traditional machines. Marx first described the composition of machines in his Das Kapital， which coincided with the start of the Second Industrial Revolution. However， within only a few years， the control system joined a machine， and Marxs “concept of machine composition” began to be broken through. In the second half of the 20th century， in the Third Scientific and Technological Revolution， the concept of mechatronics emerged， and electronic technology， control technology and sensor technology were integrated into mechanical systems. The evolution processes of the concept of machine composition were explained through the history of the development of machines herein. By analyzing the evolution of the concept of machine composition， a more accurate definition of modern mechanical systems was put forword. It may enlighten people， increase their understanding of the machine itself， which has guiding significance for modern mechanical product designers.

Molecular Dynamics Simulation for Effect of Nanoparticle Additives on Boundary Lubrication

PAN Ling, LIN Guobin, HAN Yuqing, YU Hui

2023, 34(10): 1140-1156. DOI: 10.3969/j.issn.1004-132X.2023.10.002

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The boundary lubrication behavior of Cu nanoparticles in n-hexadecane was investigated under different loads by experiments and simulations herein. Boundary lubrication model with sinusoidal rough peaks was established. The density distribution of the lubricant along the film thickness with and without Cu nanoparticles were simulated at different loads using MD respectively. The shear velocity in the opposite direction was applied to the upper and lower solid walls of the system， and the stress between the wall atoms and the copper particle atoms， the friction force of the solid-liquid interface， the normal pressure and the friction coefficient were calculated. The friction coefficient of the lubricant containing nano-copper particles was measured with a micro-nano scratch meter. The results show that the base oil n-hexadecane in the two lubrication systems is stratified under different pressures. There are still a small amount of n-hexadecane molecules at the contact interface when the nano-rough peaks are directly contacted， and the arrangement direction of the molecular main chain is the same as the shear direction. Cu nanoparticles may reduce the maximum stress of solid wall by 35.3% and improve the bearing capacity of lubrication system at 200 MPa. The lubricating oil film of lubrication system without Cu nanoparticles breaks at 50 MPa， while that of lubrication system with Cu nanoparticles breaks at 200 MPa. The friction coefficient of two lubrication system under boundary lubrication is simulated， which is in accordance with the experimental measurement.

Multi Tooth Meshing Characteristics and Load Bearing Contact Analysis Method of Cycloidal-pin Wheels

WANG Yongqiang, WEI Bingyang, XU Jiake, YANG Jianjun

2023, 34(10): 1151-1158. DOI: 10.3969/j.issn.1004-132X.2023.10.003

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The tooth profile equations of cycloidal gear were derived by the envelope methods， and the tooth surface contact parameters were obtained. An accurate algorithm for the geometry analysis of the backlash was proposed， which solved the defects that the traditional backlash algorithm might only be used for the constant displacement modification. The tooth by tooth clearance elimination methods were used to solve the deformation compatibility equation， which avoided the error and uncertainty of conventional meshing analysis and improved the calculation accuracy and efficiency of load-bearing contact analysis. The complete calculation flow from tooth surface contact analysis to load contact analysis was given， and the accurate load parameters of any angle position and different modification methods were obtained.

High-precision Microsphere Radius Measurement Model and Comparation among Roundness Evaluation Methods

LI Ruijun, DUAN Liuhui, ZHAO Wenkai, CHENG Zhenying, FAN Guangzhao

2023, 34(10): 1159-1163,1171. DOI: 10.3969/j.issn.1004-132X.2023.10.004

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A high-precision microsphere radius measurement model was proposed based on the principle of rotary axis method and two-point method， and the microsphere roundness evaluation was realized based on the amount of radius changes. A model was established that might separate the spindle runout errors and calculate the corresponding radius of each measurement points. Using the microsphere roundness measurement system developed by the authors group based on a high-precision air-bearing rotary table and two Michelson interferometers， the equatorial circular cross section of a ruby sphere with a nominal diameter of 300 μm and a roundness of 250 nm was scanned and measured. The roundness of the measured microsphere was evaluated by the minimum zone circle method， based on the measured radius by the proposed model and the calculated radius by the diameter. The results show that the roundness of the microspheres obtained by the proposed model and the conventional diameter evaluation method are as 280 nm and 403 nm with standard deviations of 2 nm and 23 nm， respectively， the proposed radius measurement model is accurate and reliable， and the roundness of the microspheres evaluated by the proposed model and the minimum zone circle method is more accurate and reliable. The proposed method may be used to obtain the radius of the measured microspheres easily and accurately， and may be applied to the accurate evaluation of the roundness of microspheres.

Experimental Research of Coarse-grained Forming Grinding Wheel Dressed by EDDG

YUAN Shangyong, CHEN Genyu, DAI Longzhou, LU Enhao

2023, 34(10): 1164-1171. DOI: 10.3969/j.issn.1004-132X.2023.10.005

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The coarse-grained metal bond diamond wheel had high grinding efficiency and good surface shape accuracy retention， which might meet the precision machining of various forming parts， but the difficulty of dressing maked it difficult to popularize. In order to solve this problem， the EDDG was proposed for coarse-grained diamond grinding wheel dressing. The influences of discharge parameters on dressing efficiency and tool loss were investigated. The discharge parameters of rough dressing were selected with the dressing efficiency as the optimization objective， and the discharge parameters of precision dressing were selected with the dressing accuracy as the optimization objective. The concave and convex arc-shaped wheels with design radius of 3 mm were used for dressing experiments. After rough dressing， the radius of concave and convex arc-shaped are as 2867.510 μm and 2919.254 μm respectively， the dimensional errors are as 4.43% and 2.69% respectively， and the PV value of profile accuracy is as 54.34 μm. After precision dressing， the radius of concave and convex arc-shaped are as 3005.107 μm and 3001.588 μm respectively， the dimensional errors are as 0.17% and 0.053% respectively， and the PV value of profile accuracy is as 17.28 μm. Finally， the dimensional errors of concave and convex arc-shaped obtained by grinding silicon carbide ceramic specimens are as 0.24% and 0.045% respectively， and the surface roughness value of the workpiece is as 0.463 μm.

An Experimental Investigation of Laser Assisted Waterjet Microgrooving of GaAs Wafers

DUAN Lingyun, HUANG Chuanzhen, LIU Dun, YAO Peng, LIU Hanlian

2023, 34(10): 1172-1183. DOI: 10.3969/j.issn.1004-132X.2023.10.006

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Comparative experiments of dry laser， low-pressure waterjet assisted laser and laser assisted waterjet processing microgrooves of GaAs wafers were conducted. The results show that laser assisted waterjet processing is suitable for processing GaAs materials, which may process high quality microgrooves without contamination on the wafer surfaces， large depth， small heat affected zone width and large depth to width ratio. And the micromorphologies of the machined surfaces are uniform with few microcracks， which are better than the other two methods. The cutting performance of laser assisted waterjet microgrooving of GaAs wafers was studied experimentally. The results show that the processing factors（laser pulse energy， waterjet pressure， processing speed， waterjet inclination angle， focal plane position， and processing times）have significant influences on microgroove depth， microgroove width and material removal rate. The microgroove depth， microgroove width and material removal rate increase with increasing laser pulse energy， decrease with increasing waterjet pressure， and the material removal rate increases significantly with increasing processing speed.

Design and Experimental Study of a Flexible Winding Forming System for Carbon Fiber Reinforced Carbon/Carbon Crucible Preform

WANG Zheng, DONG Jiuzhi, CHEN Yunjun, JIANG Xiuming,

2023, 34(10): 1184-1190,1198. DOI: 10.3969/j.issn.1004-132X.2023.10.007

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In order to solve the problems of product consistency and low production efficiency caused by manually reinforced carbon/carbon crucible preforms， a flexible winding forming system of carbon fiber reinforced crucible preform was proposed. The line type design process of crucible core die for special rotary body structure with one end plane head and one end ellipsoid head was presented based on the non-geodesic method. Each module and implementation method of computer aided line type design were introduced， and the design line type was simulated. A special winding machine with four degrees of freedom was designed according to the winding characteristics. The control system of four-axis winding machine was designed based on programmable controller and touch screen， and the winding tests were carried out. It is indicated that the winding machine runs stably and the fiber may be wound continuously and stably on the surfaces of the core die， and the system may realize automatic winding of carbon fiber reinforced carbon/carbon crucible preforms.

Influences of Vibration Feed on Electrochemical Machining Flow Fields of Surface Microstructures

WANG Chen, ZHAO Jianshe, QIANG Zhiming, ZHANG Changhao, LIU Shihao,

2023, 34(10): 1191-1198. DOI: 10.3969/j.issn.1004-132X.2023.10.008

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In order to study the effects of vibration feed on the flow fields of electrochemical machining， taking the microstructure on the surfaces of the sheets as the research object， the multi-field coupled simulation models of electrochemical machining were established to simulate the electrochemical machining processes of microstructures under the conditions of continuous feed and vibration feed， and the processing tests were carried out to study the influences of vibration feed on the flow fields. The results show that vibration feed coupled with intermittent discharge may ensure that the electrolyte is updated to an initial state with uniform conductivity distribution before the power is turned on. As the increase of the machining depths， the disturbances of the vibration motions to the flow field are weakened， and the bubble distribution along the process tends to be uniform. For the surface microstructure with a processing depth of 0～0.5 mm， the vibration feed motion with an amplitude of 0.3 mm and a frequency of 40 Hz has a better effect on improving the flow field conditions， which is conducive to improve the stability， surface quality and dimensional consistency of the electrochemical machining processes of the small microstructure on the surfaces of the sheets.

Preparation and Mechanics Properties of Al2O3/ZrO2 Ceramic Tool Materials Based on Gradient Structure

ZHOU Houming, CHEN Haoyue, LI Shengui

2023, 34(10): 1199-1207. DOI: 10.3969/j.issn.1004-132X.2023.10.009

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Al2O3/ZrO2 gradient composite ceramic tool material was prepared by vacuum hot pressing sintering， and the content of ZrO2 and the layer thickness ratio of gradient structure were optimized. The Vickers hardness， flexural strength and fracture toughness of AZE20 gradient composite ceramic tool material with layer thickness ratio of 2.0 are （18.7±0.33） GPa，（937±28.5） MPa and （8.2±0.32） MPa·m1/2 respectively. Compared with the homogeneous ceramic tool material AZ20 with the best ZrO2 content， the Vickers hardness， flexural strength and fracture toughness are increased by 22%， 37.8% and 43.8%， respectively. The design of the gradient structure makes the surface layer form the residual compressive stress， the grain is refined to a certain extent， and more ZrO2 grains are stable in the T-phase ZrO2 grain size due to the size of the residual compressive stress. It is found that the fracture mode of the composite is the combination of the transgranular fracture of the surface layer and the intergranular fracture of the middle layer， and this hybrid fracture mode improves the overall mechanics properties.

High Rigidity and Lightweight Design of Purlins in Photovoltaic Tracker Bracket

DONG Xiaohu, WANG Shitao, ZHOU Dechun

2023, 34(10): 1207-1213. DOI: 10.3969/j.issn.1004-132X.2023.10.010

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In the intelligent photovoltaic tracker brackets， cold-formed purlins were used to support the photovoltaic panels， and located spannig the horizontal single-axis and the module frame. Firstly， the minimum compliance of the structures was taken as the target and relative densities of elements were taken as the design variables， and the topology optimum design models were constructed under the given volume and the first natural frequency constraints. Optimal material distributions of the purlins were obtained based on SIMP (solid isotropic material with penalization) method， and this topology optimization structure was engineering designed and manufactured. Then， test load conditions were designed according to the practical environment where the photovoltaic tracker brackets were applied under different wind loads. The static and dynamic finite element analyses of the original and optimized purlins were carried out respectively， the simulation results show that the optimized purlins are improved in terms of bending resistance， torsion resistance， and natural frequency. Thus， the effectiveness of the optimization design method is verified. After that， the optimal purlins whose mass is reduced by 8.8% were also manufactured by engineering methods， and the mechanics performances were verified by the experiments.

Structure and Performance Control Strategy of Lightweight Aluminum Alloy Wheel Hubs under Step Quenching

CHI Hui, YAN Meng, XIANG Pengfei, XU Zhengqi, AN Zijun, HUANG Huagui,

2023, 34(10): 1214-1219,1229. DOI: 10.3969/j.issn.1004-132X.2023.10.011

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In order to realize the heat treatment deformation control of lightweight aluminum alloy wheel hubs， a new step quenching process of spray+water was proposed herein. The precision heat treatment test devices were set up and the end-face deformation detection devices were designed to analyze the deformation characteristics of lightweight aluminum alloy wheel hubs. The results show that the deformation characteristics of the inner/outer rim end-faces of the wheel hubs are affected by the structural stiffness of the wheel hubs， and the deformation characteristics of the inner rim follow the deformation characteristics of the outer rim. Due to the uneven heat transfer and internal structural defects of the wheel hubs， the overall deformation presents a certain random characteristics. The mechanics properties and hardness indexes of the monitoring points of the wheel hubs meet the requirements of the national standard under the new graded zone quenching process of spray+water. The maximum reduction of the outer rim end-face deformation is as 41.5%， which may effectively improve the heat treatment end-face deformation characteristics of lightweight aluminum alloy wheel hubs.

Effects of Amount of Galvanization on Microstructure and Mechanics Properties of Joints Made by Induction-pressure Welding of Low Alloy Steel/5052 Aluminum Alloy

GAO Kai, LI Kun, GU Hongli,

2023, 34(10): 1220-1229. DOI: 10.3969/j.issn.1004-132X.2023.10.012

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Three lap joints of low-alloy steel plates with different galvanizations and aluminum alloys were prepared using IPW technique. The effects of different amounts of galvanization on the interfacial connection state， microstructure characteristics and mechanics properties of the joints were studied. The results show that the connection interfaces of the three different amount of galvanization joints are straighter and the connection quality is good. The middle interface area of the joint consists of Fe2Al5 near the steel side and FeAl3 near the aluminum side. By comparing the microstructure and morphology of the joints with three different amount of galvanization， it is found that Zn element may improve the initial wetting mechanism at the steel-aluminum interfaces， strengthen the connection effect between aluminum alloy and low-alloy steel， and improve the mechanics properties of the lap joints. When welding with a low alloy steel plate with a galvanization of 140 g/m2， a significant zinc-rich zone defect is found at the weld toe position， resulting in a sharp drop in the shear properties of the joints. The shear properties of lap joints of low-alloy steel sheets and aluminum alloys show a trend of increasing and then decreasing with the amount of galvanization， and it is important to select a moderate thickness of galvanization to improve the mechanics properties of the joints.

Mechanism and Influencing Factors of Shape Warpage of TA2/Q235B Composite Plates during Stress Relief Annealing

WANG Rui, ZHAO Zhimin, HUANG Jing, LIU Xin, JI Xiangyun, SU Chunjian

2023, 34(10): 1230-1240. DOI: 10.3969/j.issn.1004-132X.2023.10.013

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In order to explore the mechanism and influencing factors of shape warping during stress relief annealing of TA2/Q235B composite plates， a Gleeble thermal simulation experiment was carried out to obtain the true stress and strain of TA2 and Q235B materials under different working conditions. The JC constitutive model parameters of TA2 and Q235B were determined by numerical method， and the finite element simulation model of stress relief annealing was established by combining boundary conditions such as temperature and external load. The heat treatment experiments verified the accuracy of the model. The results show that a certain tensile load may improve the strain distribution， excessive tensile load results in local concentration of residual strain， and the composite ratio and the total thickness affect the stress distribution， which will affect the strain states.

Research on Multi-axis Road Simulation Test of a New Type of Commercial Vehicle Cab

ZHOU Song, CHEN Yu, DONG Hongliang, GAO Xiang, SHEN Juan, ZHOU Jia, WAN Xinming

2023, 34(10): 1241-1250. DOI: 10.3969/j.issn.1004-132X.2023.10.014

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In order to improve the control accuracy of commercial vehicle cab multi-axle road simulation test bench and accurately reproduce the collected signals of road spectrum， a control strategy of multi-axle road virtual test bench was proposed based on kinematics and dynamics analysis. According to the principle of mechanisms， the structures of the test benches were described， the kinematics analysis and calculation were carried out. The closed-loop feedback degree of freedom decoupling was carried out by using the inverse pose solution algorithm and the forward solution algorithm with Jacobian matrix. The rigid-flexible coupling multi-body dynamics models of the cabs， part of the frames and the test benches were established by measuring the relevant parameters of the cabs and combining with ADAMS software. The Femfat-lab， MATLAB/Simulink and ADAMS software interfaces were established for adaptive co-simulation calculation to realize the decoupling control of freedom of the test bench. The multi-axis virtual test benches were combined with the internal response signals of the real vehicle tests， and the signals with high signal-to-noise were selected as the target signals for iterative analysis to obtain the equivalent displacement excitation of the real vehicle positions. The typical Belgian road load spectrums were selected as the input condition of the models to reproduce the real road spectrums combined with the road tests. The research results show that compared with the indoor road simulation test benches and the conventional virtual iteration results， the number of iterations of the cabs using the multi axis virtual test benches is significantly reduced， the change trend of the time domain and frequency domain response signals obtained is consistent with the target signal， and the root mean square value of the relative error of each channel is less than the set value， so the iteration accuracy is high. Furthermore， the feasibility of the method was verified， which provided a reliable load spectrum for the subsequent fatigue life prediction of the cabs.

Pivot Steering Control of Off-road Vehicles Driven by In-wheel Motors

FU Xiang, LIU Zexuan, , LIU Daoyuan, LI Dongyuan,

2023, 34(10): 1251-1259. DOI: 10.3969/j.issn.1004-132X.2023.10.015

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In order to solve the problems of large minimum turning radius and inadequate steering maneuverability of Ackermann steering-based off-road vehicles， a road adaptive pivot steering control strategy was developed by taking advantages of the independent control of vehicle torque driven by in-wheel motors. A seven-degree-of-freedom pivot steering dynamics model was constructed to explain the evolution of the longitudinal and transverse coupled motion tire forces during pivot steering， and a quantitative model was established to quantify the pivot steering resistance moment and transverse sway moment with wheel slip rate and road adhesion coefficient. The desired trajectory of transverse sway angular velocity under different adhesion conditions was designed with steering power responsiveness as the optimization objective， and the safety threshold of each wheel slip rate was used as the stability constraint to reduce the steering center offset. The executive layer tracked the transverse angular velocity based on the model prediction algorithm， while the adaptive sliding mode controller was introduced to adjust the wheel slip rate to ensure the stability of the longitudinal and transverse motions. Simulation tests and real vehicle tests show that the developed pivot steering control strategy achieves accurate tracking of the desired pivot steering trajectory under high， medium and low adhesion surfaces， and limits the steering center offset to within 500 mm， which improves the pivot steering flexibility and lateral stability of the off-road vehicles and realizes "fast and stable" pivot steering.

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