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Design and physical model experiment of an attitude adjustment device for a crawler tractor in hilly and mountainous regions

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Information Processing in Agriculture 2020年第3期7卷 466-478页

作者： Jingbin Sun Chong Meng Yazhou Zhang Guoping Chu Yanjie Zhang Fuzeng Yang Zhijie Liu College of Mechanical and Electronic Engineering Northwest A&F UniversityYanglingShaanxi 712100China Scientific Observing and experimental Station of Agricultural Equipment for the Northern China Ministry of Agriculture PR ChinaYanglingShaanxi 712100China State Key Laboratory of Soil Erosion and Dryland Farming on Loess Plateau YanglingShaanxi 712100China

To address the problems of difficult leveling and poor stability of hill crawler tractors,an attitude adjustment device based on a parallel four-bar mechanism was designed,and the mechanical reasons for the sideslip instability of hill crawler tractors were *** this basis,a posture adjustment mechanism based on a parallel four-bar mechanism was proposed,and the structure of the complete attitude adjustment device was *** ensure that this device meets the strength requirements during operation,a mechanical analysis of the key components(active rocker and slave rocker)was carried out to accommodate the load during *** on ANSYS software,a finite element simulation analysis was used to determine the maximum stress position of the active and slave ***,to verify the accuracy of the above simulation analysis results and determine the influence rules of the lateral slope angle,longitudinal slope angle and loading quality on the abovementioned maximum stress,a physical model test bench of the attitude adjustment device was *** orthogonal regression experiment was carried out with the maximum stresses of the active and slave rockers as the test *** experimental data were analyzed by Design-Expert 10 software,and the results show that the order of the primary and secondary factors influencing the maximum stress of the active rocker was the loading mass,lateral slope angle and longitudinal slope *** order of the factors influencing the maximum stress of the slave rocker was the longitudinal slope angle,lateral slope angle and loading *** active and slave rockers meet the strength *** work provides technical support for the production of hill crawler tractor physical prototypes.

关键词： Hill crawler tractor Attitude adjustment Mechanical analysis physical model experiment

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The influence of inter-band rock on rib spalling in longwall panel with large mining height

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International Journal of Mining Science and Technology 2024年第4期34卷 427-442页

作者： Jiachen Wang Meng Li Zhaohui Wang Zheng Li Han Zhang Shixiong Song School of Energy and Mining Engineering China University of Mining and Technology-BeijingBeijing 100083China Coal Industry Engineering Research Center of Top-coal Caving Mining Beijing 100083China Faculty of Engineering Hokkaido UniversitySapporo 060-8628Japan

In order to improve rib stability,failure criteria and instability mode of a thick coal seam with inter-band rock layer are analysed in this study.A three-dimensional mechanical model is established for the rib by considering the rock layer.A safety factor is defined foy the rib,and it is observed that the safety factor exhibits a positive correlation with the thickness and strength of the inter-band rock.A calculation method for determining critical parameters of the rock layer is presented to ensure the rib *** is revealed that incomplete propagation of the fracture at the hard rock constitutes a fundamental prerequisite for ensuring the rib *** influence of the position of the inter-band rock in the coal seam on failure mechanism of the rib was thoroughly investigated by developing a series of physical models for the rib at the face *** best position for the inter-band rock in the coal seam is at a height of 1.5 m away from the roof line,which tends to provide a good stability state for the *** different inter-band rock positions,two ways of controlling rib by increasing supports stiffness and flexible grouting reinforcement are proposed.

关键词： Rib spalling Inter-band rock Large mining height Limit analysis physical model experiment Numerical simulation

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Hydrodynamic Performance and Power Absorption of A Coaxial DoubleBuoy Wave Energy Converter

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China Ocean Engineering 2023年第3期37卷 378-392页

作者： LI De-min DONG Xiao-chen LI Yan-ni HUANG He-ao SHI Hong-da College of Engineering Ocean University of ChinaQingdao 266400China Shandong Provincial Key Laboratory of Ocean Engineering Qingdao 266100China Qingdao Municipal Key Laboratory of Ocean Renewable Energy Ocean University of ChinaQingdao 266100China

As an important wave energy converter(WEC),the double-buoy device has advantages of wider energy absorption band and deeper water adaptability,which attract an increasing number of attentions from *** paper makes an in-depth study on double-buoy WEC,by means of the combination of model experiment and numerical *** Response Amplitude Operator(RAO)and energy capture of the double-buoy under constant power take-off(PTO)damping are investigated in the model test,while the average power output and capture width ratio(CWR)are calculated by the numerical simulation to analyze the influence of the wave condition,PTO,and the geometry parameters of the *** AQWA-Fortran united simulation sy stem,including the secondary developme nt of AQWA software coupled with the flowchart of the Fortran code,models a new dynamic *** viscous damping and hydraulic friction from WEC system are measured from the experimental results,and these values are added to the equation of *** a result,the energy loss is contained in the final numerical model the by united simulation *** the developed numerical model,the optimal period of energy capture is *** power capture reaches the maximum value under the outer buoy's natural *** paper gives the peak value of the energy capture under the linear PTO damping force,and calculates the optimal mass ratio of the device.

关键词： coaxial double-buoy wave energy converter physical model experiment numerical simulation hydrodynamic performance

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基于鸟类脖颈结构的仿生超冗余机器人

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Acta Mechanica Sinica 2023年第5期39卷 132-143页

作者：何俊峰文桂林刘杰 School of Mechanical and Electric Engineering Guangzhou UniversityGuangzhou510006China Hebei Innovation Center for Equipment Lightweight Design and Manufacturing Yanshan UniversityQinhuangdao066004China

一些鸟类的脖颈具有出色的柔性弯曲能力,模仿其特性可以设计仿生机器人.该类仿生设计的主要挑战是如何处理鸟类脖颈固有的灵活性和冗余的自由度.本文以鸡的脖颈结构为例,提出了一种模仿其脖颈结构特征的仿生超冗余机器人的设计方法.在... 详细信息

一些鸟类的脖颈具有出色的柔性弯曲能力,模仿其特性可以设计仿生机器人.该类仿生设计的主要挑战是如何处理鸟类脖颈固有的灵活性和冗余的自由度.本文以鸡的脖颈结构为例,提出了一种模仿其脖颈结构特征的仿生超冗余机器人的设计方法.在我们的设计中,首先研究鸡脖颈的多骨节连接与运动特性,并定义了一个具有弹簧和万向节组合的仿生椎骨单元(BVU)来模拟鸡脖颈结构.然后,由三根钢丝平行驱动的三个仿生椎骨单元形成单个颈椎节段.最后,连接四个相同的颈椎节段构成了所提出的仿生超冗余机器人.结合几何分析法和Denavit-Hartemberg(D-H)参数法,研究了仿生超冗余机器人的驱动空间、关节空间和任务空间的运动学关系.通过蒙特卡洛方法进一步计算了可达工作空间.此外,原型样机的单平面运动实验的最大位置偏差约为四个颈椎节段总长度的5.8%.同时,一系列空间形状的展示,包括S形仿生弯曲配置和对兴趣目标体的成功缠绕和提升,证明了所提出的设计方法的有效性、机器人具有优异的灵活性和应用潜力.

关键词： Bird’s neck Bionic hyper-redundant robot Kinematic analysis physical model experiment

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Study on Wave Dissipation of the Structure Combined by Baffle and Submerged Breakwater

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China Ocean Engineering 2017年第6期31卷 674-682页

作者： JU Lie-hong zuo Qi-hua TENG Ling WANG Xing-gang Nanjing Hydraulic Research Institute Nanjing 210029 China College of Harbor Coastal and Offshore Engineering Hohai University Nanjing 210098 China Key Laboratory of Port Waterway and Sedimentation Engineering of the Ministry of Transport Nanjing 210029 China

This paper proposes a structure combined by baffle and submerged breakwater （abbreviated to SCBSB in the following texts）. Such a combined structure is conducive to the water exchange in the harbor, and has strong capability on wave dissipation. Our paper focuses on the discussion of two typical structures, i.e., the submerged baffle and rectangular breakwater combined with the upper baffle respectively, which are named as SCBSB 1 and SCBSB2 for short. The eigenfunction method corrected by experimental results is used to investigate the wave dissipation characteristics. It shows that the calculated results agree well with the experimental data and the minimum value of the wave transmission coefficient can be obtained when the distance between the front and rear structures is from 1/4 to 1/2 of the incident wave length.

关键词： combined wave dissipation structure eigenfunction method physical model experiment transmissioncoefficient correction wave dissipation effect

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Directional arrangement of phyllite fragments in phyllite talus slopeat the eastern margin of the Tibetan Plateau

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Journal of Mountain Science 2021年第11期18卷 3069-3081页

作者： WAN Yu-hao ZHAO Xiao-yan LING Si-xiang LI Jin ZENG Cai-yun BERND Wünnemann Faculty of Geosciences and Environmental Engineering Southwest Jiaotong UniversityChengdu 611756China

Phyllite fragments are essential for accumulating and generating talus slope at the toes of hillslopes,however,how they are linked to slope failure remains *** paper reports the directional arrangement of phyllite fragments(DAPF)in phyllite talus slope at the eastern margin of the Tibetan *** investigation,mathematical statistics and model experiments were performed in order to systematically understand the influencing factors,which include fragment shape,flat ratio,dip angle(α),and fine particle content(c).The results show that the quadrilateral fragmentgenerates a similar imbricate structure more easily than the triangular and rod fragments in the phyllite talus ***,the flat phyllite fragments easily accumulate as imbricated structures on the phyllitetalus *** the dip angle(α)is in the range of 20°–30°,the minimum orientation ratio(P)is more than 50%,which means thatthe DAPF phenomenon is more obviousin the phyllite talus *** the fine particle content(c)at the same dip angle(α),the minimum orientation ratio(P)is 54%,and the minimum orientation ratio(P)correlates positively with the fine particle content(c).Therefore,compared with the homogeneous talusslope,the phyllite talusslopedisplays a special DAPF *** study provides a valuable reference and presents novel knowledgefor risk assessment and engineering design against the phyllite talus slope failure mechanism.

关键词： Phyllitefragment Talus slope Directional arrangement physical model experiment Field investigation

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LIFTING FORCE ACTING ON A GATE WITH HIGH HEAD

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Journal of Hydrodynamics 2011年第3期23卷 379-383页

作者： LIU Xiao-qing ZHAO Lan-hao CAO Hui-ying SUN Xiao-peng College of Water Conservancy and Hydropower Engineering Hohai University Nanjing 210098 China

The hydrodynamic lifting force acting on a gate with high head is one of the key factors concerning the safety and reliability of gates. The lifting force is closely related to hydrodynamic pressure, and generally, is obtained through the model test. This work presents a method of numerical simulation based on the VOF method for the flow and FEM for the structure of a gate to investigate this kind of the lifting force. The physical model experiments were conducted about the hydrodynamic pressure and the lifting force to verify the numerical results. The comparisons of those two methods show that the maximum relative error is smaller than 11.40 % and the method presented in this paper is feasible and could be used in the designs of hydropower projects.

关键词： gate pressure high head lifting force numerical simulation physical model experiment

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