Table of Content

10 September 2023, Volume 34 Issue 17

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Influences of Gas Port Parameters on In-cylinder Pressures of Annular Connecting Straight Cylinder Engines

XU Haijun, YANG Congnan, CAI Tong, GAO Xue

2023, 34(17):  2017-2025,2047.  DOI: 10.3969/j.issn.1004-132X.2023.17.001

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 A dynamic position gas distribution system was introduced based on airway reuse for an innovative ACSCE. Combined with the differential rotation characteristics of dual rotor cylinders， a mathematical model of the dynamic position gas distribution structure and a thermodynamic model of the working processes of ACSCEs were established， and the influences of different structural parameters of the gas distribution system， including the position angle， size and shape， on in-cylinder pressures of ACSCEs were analyzed. The numerical calculation method was used to solve the thermodynamic equations， and the results show that the position angle of the intake and exhaust ports of the central valve shaft（CVS） has a greater impact on in-cylinder pressures， while the port size of CVS has a relatively small effect， and the port size of the rotary valve（RV） also has a great impact on in-cylinder pressures， while the port shape has less effect. The results of high-pressure pneumatic experiments on the engine indicate that when the intake port position angle is as 78°， the exhaust port position angle is as 30°， the intake port size is as 10 mm， the exhaust port size of CVS is as 14 mm and the port size of RV is as 6 mm， the ACSCE may be in correct gas distribution state and work stably. 

Simulation and Experimental Study of Contact-collision of Inner Braced Manipulators for Grasping Thin-walled Fragile Cylindrical Inner Wall Workpieces

WANG Liangwen, KONG Yangguang, WANG Ruolan, ZHANG Zhigang, LIU Xuling, LI Linfeng,

2023, 34(17):  2026-2036.  DOI: 10.3969/j.issn.1004-132X.2023.17.002

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Aiming at the operation demands grasping the thin-wall fragile parts in industrial production， an inner braced working manipulator configuration with finger-palm collaborative features was proposed. In order to find the appropriate operational parameters of the manipulators fingers， and explore the stress change law on contact-collision for the grasping processes， the finite element model of the finger parts for the manipulator was established by integrating HyperMesh and LS-PrePostto model. After applying the corresponding constraints， loads and contact types to the finite element model， the stress and strain cloud images for the fingers and the fragile parts on the contact-collision processes were obtained by calculation. The simulation results show that the stresses of the fragile parts increase linearly with the increasing of the fingers impact speeds. When the speed changes from 0.5 to 2.5 mm/ms， the stress increases to 3 to 4 times the original. With the increasing of the wall thickness of fragile parts， the fragile parts stresses decrease gradually. The stress changes obviously at the stage of thin wall thickness， the average stress variation of the wall thickness of 0.51.0 mm is 67 times that of the wall thickness of 1.02.5 mm. When the manipulator applies different acceleration at the contacting fragile parts moment， as the acceleration increases， the contact stress increases accordingly， the average stress change for acceleration of 1.02.5 mm/ms2 is 89 times that of the acceleration of 0.51.0  mm/ms2. According to the existing simulation results， the Kriging agent model is established to calculate the prediction model of the contact stresses under the different wall thickness and grasping speed， which establishes the foundation for determining the grasping parameters of the manipulators， designing and optimizing the finger structures under different conditions. By constructing an experimental system， the simulation results were verified experimentally， and the correctness of the simulation results was proved. 

Influences of Horizontal Forced Vibration Finishing on Surface Integrity Parameters of TC4 Titanium Alloys

HAN Rui, LI Xiuhong, WANG Jiaming, LI Wenhui, CHENG Siyuan, YANG Shengqiang,

2023, 34(17):  2037-2047.  DOI: 10.3969/j.issn.1004-132X.2023.17.003

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 To explore the influences of horizontal forced vibration finishing on the surface integrity of TC4 titanium alloy specimens， a single factor experiment was designed to analyze the effects of main processing parameters on surface roughness， microhardness， surface residual stress and contact angle， a better combination of processing parameters was obtained. The changes of the surface morphology， microstructure and surface lattice of the specimens were analyzed before and after processing under the optimal parameters. The results show that particle diameter is the main factor affecting surface roughness， microhardness and surface residual stress. As the particle diameter becomes larger， the roughness reduction rate increases first and then decreases， and the microhardness and surface residual compressive stress become larger. With the increasing of amplitude and frequency， the decreasing rate of surface roughness， microhardness and surface residual compressive stress increase. The maximum decreasing rate of surface roughness Ra， Rq， Rz， Rt and RSm may reach 65.0%， 62.2%， 45.2%， 42.0% and 73.7% respectively. Microhardness may be increased from 320.8HV0.1 to 363.9HV0.1. The residual compressive stress may be changed from -420.38 MPa to -621.25 MPa. The surface peaks are removed. A dense layer is formed on the surface， and the grain structure is refined. The diffraction peak is shifted and the greater residual compressive stresses are introduced. 

Design and Service Performance Optimization of Induction Heating Methanol Reforming Devices Based on Fluid Pressure Drop Control

XIAO Gang, ZHANG Bin, LI Shichun, YAN Huijun, YANG Qinwen

2023, 34(17):  2048-2057,2076.  DOI: 10.3969/j.issn.1004-132X.2023.17.004

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Based on the consideration of fluid pressure drop control， a new type of induction heating reforming device was proposed. The service performance simulation model and prediction model of the system were constructed. The influences of key parameters on energy conversion and reforming transformation were analyzed， and the collaborative optimization design of the system supercharging structure and operating parameters was completed. The results show that with the increasing of the overlap degree of the pressurized heating plate， the angle toward the inlet and the acute angle decreases gradually， the electric-hydrogen energy conversion ratio， methanol conversion and hydrogen yield increase significantly. Meanwhile， the temperature difference and flow energy loss of the reaction gas before and after conversion increase. The maximum electric-hydrogen energy conversion ratio， the minimum temperature difference and flow energy loss before and after conversion were set as the comprehensive optimization objectives. The optimization was carried out by using single hidden layer back propagation（BP） neural network and genetic algorithm（GA）， and the results show that when the overlap degree of pressurized heating plate is as 0.45， the angle is as 75° toward the inlet， the reactant supply flow velocity is as 1.1 m/s， the net power of the reformer is as 460 W. Compared with the control structure without fluid pressure drop， the electro-hydrogen energy conversion ratio of the proposed reformer is improved by 64.17%. 

Quantitative Study on Magnetic Anomaly of Superalloy Surface Defects Based on Parameter Optimization of SVM

HU Bo, LUO Weitao, WANG Shaofei, LAN Xiwang

2023, 34(17):  2058-2064.  DOI: 10.3969/j.issn.1004-132X.2023.17.005

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The quantitative method of magnetic anomaly of superalloy surface defects based on the parameter optimization of SVM was of great significance to solve the engineering problems of surface crack detection for turbine disks. A sample database was constructed with 16 preset magnetic anomaly characteristic values of defects obtained by weak magnetic detection, a SVM prediction model was established to invert and quantify of defect sizes. The validity of parameter optimization and the SVM model were verified by the specimens with known defects. The results show that after parameter optimization, the prediction results of length, width and depth are improved compared with the prediction results of default parameters, especially the inversion effectiveness of length and depth are significantly improved, and the prediction accuracy of genetic algorithm is better than that of cross-validation method. When the magnetic permeability of the defect and the base material is very different, such as ferromagnetic inclusions on the surfaces of the superalloy, the characteristic value amplitude of the magnetic anomaly is more larger. After the characteristic value amplitude and area are halved, the accuracy of the results is improved by more than 20%. The SVM model with genetic algorithm parameter optimization still shows good predictive ability for data outside the sample database, and the prediction accuracy is close to 85%.

Research on Flexible Job-shop Scheduling Problems Considering Optimization of Worker Number Allocation#br#

LIANG Xianglin, SONG Yuchuan, LEI Qi, SUN Aihong

2023, 34(17):  2065-2076.  DOI: 10.3969/j.issn.1004-132X.2023.17.006

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Under the background of the shortage of workers and the increasing of workers costs， it was very important to complete the manufacturing tasks with a reasonable allocation scheme of the number of workers.  Previous studies of flexible job-shop scheduling considering worker constraints assumed that the number of workers was given.  In order to optimize the number allocation of workers with different technical levels and flexible job-shop scheduling in an integrated way， considering the penalty cost， worker base cost and performance cost， a mixed integer programming model was established to minimize the total cost， and an improved TLBO algorithm was proposed to solve the problems.  In the algorithm， an activity scheduling decoding method was designed based on the three-layer coding of worker number allocation， operation sequencing and machine selection.  A hybrid heuristic initialization method was used for initialization. An effective neighborhood structure was designed for the problem features.  The tests of several groups of examples were verified that the proposed algorithm may determine the actual number of workers with different technical levels and obtain the excellent scheduling scheme， and is superior to the comparison algorithms in performance. 

Research on Multi-objective Golden Eagle Optimizer for No-tardiness Job Shop Scheduling Problems with Overtime Consideration

SHI Shuangyuan, XIONG Hegen

2023, 34(17):  2077-2088.  DOI: 10.3969/j.issn.1004-132X.2023.17.007

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Delivery on time was one of the important goals of the production operations in make-to-order industries. When the production load of the manufacturing system was heavy， overtime work was the most commonly used effective measure to ensure the delivery time. In order to realize the no-tardiness delivery of order tasks and the optimal use of overtime hours， a multi-objective no-tardiness job shop scheduling problem considering overtime was proposed， and a mathematical model with the objective of minimizing the total overtime hours and the makespan was established. To solve the problem effectively， a multi-objective golden eagle optimizer was proposed. In the algorithm， a coding method was designed to map the continuous solution space to the discrete solution space of the problem， a two-stage decoding scheme was proposed， an elitist no-dominated sorting selection operator was integrated， and an adaptive offspring individual generation strategy was introduced. The effectiveness and superiority of the proposed algorithm were verified by comparison experiments on 23 modified job shop scheduling problem benchmarks as experimental objects. 

Research on Compliant Legs of Bionic Hexapod Robots

WANG Wei, WEI Lang, LIU Fusheng, WANG Guoshun

2023, 34(17):  2089-2094.  DOI: 10.3969/j.issn.1004-132X.2023.17.008

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In order to explore the specific influences of the curved legs with compliance on the motion performance of the bionic hexapod robots， firstly， the PRB model was used to describe the deformation features of the curved legs， and the mathematical expression of the stiffness was given.  Then， based on the stiffness model， a virtual prototype was built in the Webots simulation environment， and the changes in velocity and energy consumption rate of the bionic hexapod robots were analyzed by setting different stiffnesses of the curved legs.  Finally， the curved legs with different stiffness were fabricated and verified in the physical prototype.  The results show that the compliance of the curved legs may be more accurately described by the PRB model， which improves the velocity of the bionic hexapod robots and reduces the energy consumption. 

Numerical Simulation of Residual Stress and Welding Deformation for High Strength Steel Q960E Butt-welded Joints

LUO Wenze, CHENG Huimei, LIU Hongyan, WANG Yifeng, YE Yanhong, DENG Dean

2023, 34(17):  2095-2105,2141.  DOI: 10.3969/j.issn.1004-132X.2023.17.009

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 A multi-pass butt-welded joint of low alloy high strength steel Q960E was prepared by equal strength matching wire and mixed gas shielded welding method. Microstructure， hardness distribution， welding temperature cycles， welding deformation and welding residual stress were observed and measured by experiments. With the consideration of the microstructure characteristics of Q960E， a thermal-elastic-plastic finite element method which considered the coupling behaviors among multiple physical fields of “thermal-microstructure-stress” was developed based on SYSWELD software platform. The material model focused on solid-state phase transformation in the heat-affected zones（HAZs）. The JMAK equation was employed to describe the austenitization processes during the heating stages， while the K-M equation was utilized to simulate the martensitic transformation processes in the cooling stages. At the same time， the transformation-induced plasticity in the cooling processes was considered based on the Leblond model. The comparison between the numerical simulation results and the experimental measurements shows that both the residual stress distribution and the welding deformation obtained by the finite element model are in a good agreement with the measured data， and the numerical simulation results also show that the solid-state phase transformation has a significant effect on the distribution and magnitude of welding residual stress in the HAZ of Q960E steel butt-welded joints. 

Determination Method of Stress-Strain Constitutive Relationship of Weld Materials for High-grade Steel Pipelines

ZHANG Dong, LIU Xiaoben, KONG Tianwei, YANG Yue, WU Xuejian, WU Kai, ZHANG Hong

2023, 34(17):  2106-2114.  DOI: 10.3969/j.issn.1004-132X.2023.17.010

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As a key weak link of oil and gas pipelines， the girth weld of high-grade steel pipeline was always concerned by the engineering and scientific research communities.  As a typical welding structure， the welds had obvious heterogeneity， which led to the inability to accurately test the axial mechanics properties of girth weld materials， which seriously affected the accuracy of safety evaluation of pipeline girth welds.  Based on MATLAB-PYTHON-ABAQUS co-simulation， an optimization inversion method of the material stress-strain constitutive relationship was proposed in the weld zones for the high-grade steel pipelines.  Four groups of uniaxial tensile tests with different notch sizes were carried out， and the load-displacement curves of each sample were obtained.  The true stress-strain constitutive relationship of the weld zone materials was obtained by BRBP neural network and GWO， and the accuracy of the constitutive relationship was fully verified by the testing data， the results show that the relative error is less than 1%.  The inversion method proposed is also suitable for the determination of stress-strain curves of homogeneous metal materials in large strain ranges.  The inversion method may provide accurate stress-strain constitutive relationship and strength matching relationship for the safety evaluation of girth welds of high-grade steel pipelines， and further ensure the safe operation of oil and gas pipelines. 

Numerical Simulation and Experimental Investigation of Flow Fields in Vehicle Climatic Chambers

XU Xiang, ZHANG Yilun, MEI Zheng, LI Jian, WANG Dan, MU Liansong

2023, 34(17):  2115-2123.  DOI: 10.3969/j.issn.1004-132X.2023.17.011

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The experimental method was used to study the wind velocity distribution， boundary layer thickness， axial static pressure gradient and dynamic pressure stability and other flow field characteristics in the vehicle climatic chambers without a car. The numerical simulation method was used to establish a 1∶1 model of the vehicle climatic chambers， and the interference effects of various experimental facilities and equipment on the flow field in the climatic chambers were considered， and the numerical simulation of the flow field distribution in the climatic chambers was conducted. The results show that the flow field in the vehicle climatic chambers is relatively turbulent， and the flow field in the test section results show a dispersive jet state. The wind speed distribution at the outlet of the main fan is not uniform， and the difference between the highest and lowest wind speeds is as 36 km/h. The wind speed decays significantly after the airflow from the fan， and the axial static pressure gradient changes greatly. The boundary layer of the airflow in the test section is thicker， and the thickness of the boundary layer increases the farther away from the fan center direction. The numerical simulation results show that the installation position and size of the main fan have some influences on the flow field of the climatic chambers， and increasing the size of the fan outlet may improve the flow field quality of the climatic chamber test sections. 

Research on Influences of Main Digging Force Arm Ratio on Definition of Main Digging Area and Evaluation of Digging Performance

LI Jiahao, REN Zhigui, PANG Xiaoping, WANG Junli, CAO Shusheng, YU Songsong

2023, 34(17):  2124-2141.  DOI: 10.3969/j.issn.1004-132X.2023.17.012

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The digging performance of the main digging area was a key indicator in the analysis and evaluation of digging machine performance， and the scope definition directly affected the evaluation results， while the operating force arm was inseparable from the operating range and digging force performance. Taking a 22 t backhoe hydraulic excavator as an example， the concept of force arm coefficient was introduced and based on the force arm curve and the transmission ratio curve of each mechanism， different main digging force arm coefficients were selected and the force arm variations caused by different digging methods were used as the basis to establish the main digging force arm proportioning scheme. Based on the work domain mapping analysis method and the limit digging force model， the theoretical digging force and the limiting factors were solved to analyze the digging performance of different main digging areas separately. The results show that for the working ranges， the bucket force arm mainly affects the digging height and discharge height， the bucket bar force arm mainly affects the digging diameter and the moving arm force arm mainly affects the digging depth and digging height. For digging performance， increasing the force arm of an operating cylinder may increase the digging force， while the corresponding operating cylinder full play ratio may decrease； on the contrary， increasing the force arm of a non-operating cylinder may have less effect on the digging force， but the operating cylinder full play ratio may increase； the bucket rod force arm mainly affects its average digging force， while the bucket force arm mainly affects its maximum digging force. Then， the main digging area formed by the 0.6∶0.8∶0.6 force arm coefficient ratio for bucket rod digging and the 0.6∶0.8∶0.8 force arm coefficient ratio for bucket and compound digging is taken as the best digging performance main digging area for their respective digging methods. The paper proposes a method of defining the main digging zone by the ratio of the main digging force arm coefficient， revealing the influences of different main digging force arm ratios on the digging performance， providing evaluation indicators and reference directions for digging performance analysis and working device optimization.