Table of Content

25 June 2023, Volume 34 Issue 12

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Finite Element Analysis for Extrusion, Assembly and Loosening Processes of Hi-lock Nuts

ZHANG Jingdong, DENG BoGUI Xuewen, LI Jian, LIAO Ridong

2023, 34(12):  1387-1394，1406.  DOI: 10.3969/j.issn.1004-132X.2023.12.001

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 The FE（finite element） modeling method of UNJ threaded hi-lock nuts was investigated, and a modeling program was written to generate structured meshes, through which the fine FE meshed model was established. The extrusion process, assembly process and loosening behavior under transverse loads of hi-lock nuts were simulated by finite element method（FEM）, and the simulated locking torque was verified by tightening tests. The simulation results show that within a certain range, the maximum radial displacement and the locking torque of the hi-lock nuts are linearly related to the extrusion amount approximately. With the extrusion amount increases, the maximum radial displacement and the locking torque both increase. The higher the locking torque of the hi-lock nuts, the better the anti-loosening performance. However, there is an optimal value of the extrusion amount for the anti-loosening performance. Once the extrusion amount exceeds the optimum value, increasing the amount of extrusion does not have a significant effect on the improvement of the anti-loosening performance.

Experimental Study of Shear Cavitation in Two-dimensional Piston/Cylinder Pairs Micro-gap Flow Fields

DING Chuan, ZHANG Lichao, XIA Ning, CHEN Haoqi, RUAN Jian, MENG Bin,

2023, 34(12):  1395-1406.  DOI: 10.3969/j.issn.1004-132X.2023.12.002

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 Two-dimensional hydraulic components could benefit from the surface sealing and circumferential distribution of two-dimensional pistons, but they might face cavitation due to oil shear in the gap between the piston and cylinder body. In order to investigate the one-dimensional motions of the oil in the gap, a shear rheology device with a rotating outer cylinder was established to carry out visual studies of shearing flow, including the influences from various rotating speeds, fluid pressures, air ratios in the space above the shearing fluid field, inner cylinder outer wall surface with chute structure and micro-gap thickness. The experimental results demonstrate that the increase of flow field pressure linearly leads to larger critical shear stress， the more air there is in the space above the shearing fluid field, the stronger the effect of preventing shear cavitation， the two-dimensional pistons flow distribution groove structure will reduce the shear torque of the oil on the one hand, and change the pure shear flow field on the other hand, thus inhibiting the occurrence of shear cavitation， the decrease of gaps will decline critical shear stress, which makes the generation of the shearing cavitation ease.

Detecting Internal Leakage in Electro-Hydraulic Actuators Based on Operational States of Motor

HE Qingchuan, LIU Hui, PAN Jun, CHEN Wenhua

2023, 34(12):  1407-1414.  DOI: 10.3969/j.issn.1004-132X.2023.12.003

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 Internal leakage in an electro-hydraulic actuator（EHA） could not be identified by observation and also there were no effective methods for online detecting by using operational data. According to the relationship between state parameters of motor and leakage in closed hydraulic system, a detecting method of internal leakage by using motor current and speed signals was proposed. Based on deep learning algorithm, a convolution neural network was proposed which could be used to extract targeting weak features from monitoring data. A fault injection experiment was designed and the results show that the detection accuracy of internal leakage reaches 98.7% by using the proposed method, which provides an effective method for internal leakage detection in EHAs.

Collaborative Optimization of Stacking Sequence and Material Distribution for Wing Skins

PENG Xiang, JIANG Haohao, GUO Yuliang, LI Jiquan, YI Bing, JIANG Shaofei,

2023, 34(12):  1415-1424,1435.  DOI: 10.3969/j.issn.1004-132X.2023.12.004

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To realize the lightweight and shock absorption design of the wing skins, the hybrid composite materials were introduced into the design of wing skins, and a collaborative optimization design method of stacking sequences and materials distribution was proposed for wing skins. The stacking sequences and material distribution of the wing skins were taken as the optimization design variables, the collaborative optimization model with cost as constraint, minimization of skin mass and displacement, and frequency maximization as objectives was established. The multi-objective collaborative optimization problem of the wing skins was carried out by using the NSGA-Ⅱ based on the developed optimization design framework of the wing skins. Compared with the performance of aluminum alloy wing skins and initial structure scheme, the optimized stacking sequences and material distributions may significantly improve the comprehensive performance of the wing skins without increasing the costs, which verifies the effectiveness of the proposed method.

Design and Performance Analysis of 8R Two-translational Spatial Parallel Mechanism with Motion Decoupling and Symbolic Positive Solutions

DU Zhongqiu, SHEN Huiping, MENG Qingmei, LI Tao, YANG Tingli

2023, 34(12):  1425-1435.  DOI: 10.3969/j.issn.1004-132X.2023.12.005

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 Two new 8R two-translational(2T) spatial PMs(PM 1 and PM 2) were proposed, and their degree of freedoms(DOF) were analyzed and calculated. The forward and inverse solutions of the symbolic positions of the two PMs were derived, and the workspace of the two PMs was analyzed based on the symbolic forward solution. The stiffness and dynamics of the two PMs were modeled respectively, the stiffness performance of the two PMs was analyzed, and the driving torque of the two PMs under the same load was obtained. Finally, the kinematics, stiffness and dynamic properties of the two PMs were compared, which shows that PM 2 is the preferred model.

NURBS Curve-based Multi-objective Aerodynamic Optimization Design for Ultra-high-speed Elevator Fairings

CHEN Xiren, YE Wenhua, ZHANG Chaohong, CUI Kunkun, LENG Sheng, YE Liukang

2023, 34(12):  1436-1445,1464.  DOI: 10.3969/j.issn.1004-132X.2023.12.006

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With the increase of elevator speed, the aerodynamic drag and lift forces of the car became more and more great, which restricted the further improvement of elevator speed, and became the key factor affecting elevator comfort and safety. In order to optimize the aerodynamic performance of the elevators, a parameterized model of the elevator systems including fairing, car, counterweight and hoistway was built using NURBS curves. Taking aerodynamic drag coefficient Cd and aerodynamic lift coefficient Cl as optimization objectives, four key design parameters with the greatest impact on optimization objectives were selected by sensitivity analysis. In order to shorten the calculation time, a Kriging model was established to carry out multi-objective optimization of the fairings by checking the independence of the grid. A series of Pareto solutions were obtained. Finally, the aerodynamic performances of the fairings before and after optimization were compared and analyzed. The results show that the aerodynamic performances of elevator systems may be improved by reducing the convexity and concavity at the side and rear of the fairings and increasing the total height and rear height of the fairings. After optimization, Cd and Cl of the fairings are reduced by 26.67% and 34.27% respectively, and they have good applicability under different ladder speeds.

Study on Design of Wheel-leg Deformable Wheel and Vehicle Control

GENG Xueqing, WU Mengwu, HUA Lin,

2023, 34(12):  1446-1452.  DOI: 10.3969/j.issn.1004-132X.2023.12.007

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 In view of the demands of vehicle mobility and obstacle-crossing ability in complex terrain and road conditions, a deformable wheel structure was designed with the characteristics of switching between wheeled and legged states under different terrain and road conditions. The design principle of the deformable wheel was introduced and the structural parameters were calculated and optimized, the maximum diameter ratio of the wheel-leg deformable wheel was obtained. A set of simple and effective wheel-leg deformation control system was also designed. And then the vehicle layout design and movement process analysis was carried out. Finally, a prototype vehicle platform was made to verify the mobility and obstacle-crossing ability by physical experiments. The results show that the deformable wheel may be quickly and intelligently switched between wheeled and legged types, which enables the vehicle to run stably on both structured and unstructured roads, resulting in a high mobility and obstacle-crossing ability of the vehicle system.

Calculation Method of LCA Parameters for Green Design and Assessment Collaboration of Electromechanical Products

YAN Meng, LI Tao, YANG Chen, WANG Mingyu, YANG Dongdong

2023, 34(12):  1453-1464.  DOI: 10.3969/j.issn.1004-132X.2023.12.008

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In order to collaboratively analyze the green design and assessment processes of electromechanical products, the correlation mapping between green design and life cycle stages was established using the modeling method of multi-domain correlation of product design domain, life cycle activity domain and environmental impact assessment domain. The life cycle activity domain was correlated with the environmental impact assessment domain through the calculation method of life cycle assessment parameters.The LCA calculation tool was developed, and the calculation method of LCA parameters was applied to the whole life cycle stage of product green design. When the green design information was changed, just adjusting the corresponding parameters in the calculation tool, the environmental impact could be obtained after the design information was changed in real time, so as to help designers to re-design the product to green design. CWT3300D-165 wind turbine was used as a typical electromechanical product for application verification, and a product structure tree was established to calculate the environmental impact of the whole machine, components and parts of the product. From the calculation results, it may be seen that the two first-level components, foundation and nacelle, have the most serious environmental impact and need to focus on greenness in the product design stages and improve the green design scheme.

Assessment Method of Environmental Impact of Casting Processes Based on Digital Twin

GU Zhenyu, HE Yi, LI Dongyang

2023, 34(12):  1465-1475.  DOI: 10.3969/j.issn.1004-132X.2023.12.009

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Focusing on the new needs of foundry enterprises to carry out process environmental impacts and carbon emission evaluations, and addressing the issues of consistent management of dynamic data in dynamic evaluations of processes, the casting processes were taken as the research object and the digital twin technologies were introduced into the assessments of the environmental impacts and carbon emissions of the casting processes. A digital twin model of the casting processes for environmental impact assessments was constructed and integrated into the basic process of LCA evaluation, and a digital twin-based method for environmental impact assessments of the casting processes was proposed. By evolving from twin models to instance models and instance twins, the consistency of the process data structure was ensured, while the dynamic scene data carrying was realized by generating instance twins of different stages, and the management of dynamic process data was realized. Finally, the application of the proposed method in the environmental impact assessments of the processes was illustrated by the example of the 3.5-ton carrier V-normal casting processes in a foundry.

Operating Mechanism and Data Driven Approach for Fault Alarm of Wind Turbine Gearbox Systems

MENG Kang, TENG Wei, PENG Dikang, XIANG Ling, LIU Yibing

2023, 34(12):  1476-1485.  DOI: 10.3969/j.issn.1004-132X.2023.12.010

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Traditional machine learning methods were used in fault early warning of wind turbine gearboxes, the models were usually designed only by studying the relationship between data and faults, and the selection of parameters and model structure were lack of physical basis, resulting in poor interpretability and weak generalization capabilities of the models. The structure and actual operation control mode of the wind turbine gearbox were studied, the relationship between the operation mechanism and the data of corresponding supervisory control and data acquisition system was analyzed, and the operation data change trend was given qualitatively followed by deterioration of the typical gearbox faults. Finally, a series of one-class support vector machine(OCSVM) based models were constructed according to change law of the data distribution to realize the early fault warning of the wind turbines gearbox systems. Experimentsal results show that all of the proposed models may locate the fault positions of the wind turbine gearbox systems, which has clear physical significance. 

Knowledge Graph Construction Method for CAM Numerical Control Programming Field

FANG Xifeng, LIU Dakun, GONG Chanyuan, WANG Nan, ZHANG Shengwen, , WANG Tongyue

2023, 34(12):  1486-1494.  DOI: 10.3969/j.issn.1004-132X.2023.12.011

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In order to improve the ability of knowledge expression, management and mining in CAM numerial control programming field, a method to construct CAM numerial control programming knowledge graph was proposed. The information expression form of CAM numerial control programming stage was analyzed and the CAM information model was constructed. The ontology construction mode from concept to relation and from part to whole was adopted and semantic rules were introduced to realize the construction of knowledge graph pattern layer. Taking the historical CAM programming case base of a marine diesel engine enterprise as the data source, the feature-operation information unit model library was constructed, and the knowledge graph data layer was constructed by ontology mapping. By means of knowledge fusion and knowledge reasoning, the scale and quality of knowledge were enlarged and improved. Finally, a CAM knowledge graph Web platform was developed to verify the effectiveness of this method.

Study on Obstacle Avoidance Control of Concrete Pump Truck Booms Based on Pseudo-distance Method

HUANG Yi, HU Yong, FAN Jiayuan, HU Ming, TANG Qiying, Xiong Yingtao

2023, 34(12):  1495-1503.  DOI: 10.3969/j.issn.1004-132X.2023.12.012

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 Aiming at the problems of end obstacle avoidance and joint limitation of concrete pump truck boom, an obstacle avoidance method of pump truck boom was proposed based on pseudo-distance. Superquadratic function was used to represent space obstacle, and pseudo-distance was used as the index of proximity between boom and space obstacle. Based on the minimum pseudo-distance discriminant index, an obstacle avoidance speed was assigned to the boom of the pump truck, and the traditional gradient projection algorithm was improved to realize the safe obstacle avoidance of the boom of the pump truck under the condition of avoiding the joint movement exceeding the joint limit position, while ensuring the stability of the obstacle avoidance processes and the trajectory accuracy of the boom end. Simulation and semi-physical experiments verified the effectiveness of the algorithm in concrete pump truck boom obstacle avoidance processes, which may complete the space multi-obstacle avoidances.

Study on UWB Positioning Algorithm Based on Neural Networks and Self-adjusting Kalman Filters

GU Yufeng, DU Yujie, WANG Yuyang, LI Kunpeng, LI Chengshan

2023, 34(12):  1504-1511.  DOI: 10.3969/j.issn.1004-132X.2023.12.013

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A UWB positioning algorithm was proposed based on neural networks and self-adjusting Kalman filters for improving the positioning accuracy of current a certain three-line automatic driving rail transport system vehicles. The UWB tags and base stations were used to collect large amount of distance information between tags and various base stations and collect the actual locations of the corresponding tags, and the neural network was trained. The distance information between the tags and various base stations was sent to the centralized control center server through the network during the real-time positioning stage, and the real-time locations of the UWB positioning tags were obtained by the optimized neural network. The self-adjusting Kalman filter was used to improve the accuracy of the real-time tag positions furtherly. A set of UWB tag moving trajectories containing inclines, straight paths, and curves were designed for simulation based on the actual vehicle operation, and a UWB positioning system was built, the moving trajectories of the tags were designed, the UWB positioning algorithm combining the neural network and self-adjusting Kalman filter was verified through experiments. The results show that the maximum positioning error of the positioning algorithm combining neural network and self-adjusting Kalman filter is as 223.58 mm, and the average positioning error is as 43.16 mm, and the root mean square value of the positioning errors is as 42.06 mm. The positioning algorithm proposed combining the neural network and self-adjusting Kalman filter has the advantages of higher accuracy, better real-time performance and stability compared with the three-point positioning algorithm, Kalman filtering algorithm, and neural network algorithm, and the current positioning requirements of the three-line rail transports may be fulfilled.