Development of a design verification methodology including strength and fatigue life prediction for agricultural tractors

During the operations of an agricultural tractor, front axle and front axle support encounter the worst load conditions of the whole tractor. If the design of these components is not verified by systematic engineering approach, the operators of the tractor may face with sudden failures. This paper aims to develop a verification method, which involves testing an agricultural tractor on a special test track and agricultural field and together with the computer aided engineering analysis, in order to prevent such failures in the lifetime of the agricultural tractor. For this purpose, a strain gage data acquisition system has been designed to measure the strain values on the component in order to determine maximum principle stresses for the calculation of overload safety on the agricultural field and stress data for the prediction of fatigue life on a radial washboard test track. The cycle number of these stress data for the fatigue analysis has been established by rainflow cycle counting method. Total fatigue damage for the front axle support has been calculated considering damage accumulation hypothesis defined by Miner.     

Ridge-following control for agricultural tractors using deep learning and stereo camera

The furrow irrigation, which forms a ridge-furrow and grows several crops on the ridge, involves the seeding work using the tractor that follows the path of the ridge. This work requires long hours labor from human, and there is a possibility that the work efficiency may decrease. In this paper, we propose deep learning and stereo image-based algorithms for sowing tasks on ridges via autonomous path-following of the tractor. The collected stereo image is converted into a depth image through a matching algorithm, and the depth image is input to a MobileNetV2-based deep learning network model to obtain a center line of the ridge. In addition, the target value of steering angle control is calculated by waypoint preview control concept. so that the tractor can follow the estimated center line of the ridge. The proposed algorithm is verified by GPS-based path information of autonomous driving and comparing it with human-operated driving path.

     

Shift characteristics analysis and smooth shift for an automatic power transmission

Smooth shift is one of the key issues in automatic power transmission control systems. However, the torque sensors are too expensive to be used in shift controllers on production vehicles. In order to provide a basic strategy for smooth shifting by using RPM sensors only and in order to accomplish the shift within a designated time, this paper studies detailed characteristics of the smooth shift for clutch-to-clutch shift mechanism. A desired trajectory of slip speed is proposed for smooth acceleration shift defined in this paper. Also the clutch torque needed to achieve this trajectory is derived, and it may be used as a open loop shift control law.     

闪耀透射光栅衍射规律的分析和验证

基于标量理论研究了不同槽形角,不同刻线密度的透射式闪耀光栅对使用波段的影响,推导了闪耀透射光栅的衍射光能量分布规律。分析证明了透射闪耀光栅在衍射能量最强方向上衍射光的衍射角与入射光的入射角之间的关系满足Snell定律。给出了入射角、衍射角与槽形角之间的关系式,研究了不同刻线密度和槽形角条件下衍射光能量分布的规律。对闪耀透射光栅进行了测量和比较,结果表明:已有闪耀透射光栅测量的结果与理论计算数据相吻合。制备了聚二甲基硅氧烷(PDMS)可调谐闪耀透射光栅,应用研究的理论公式测量了该闪耀透射光栅在拉伸与自由状态下的闪耀波长和光栅刻线密度,结果显示其波长测量误差在5nm以内。拟合了光栅的等效槽形,验证了实时监测PDMS光栅槽形和刻线密度随拉力大小变化的规律。     

Analysis of the performance characteristics of a two-inertia power transmission system with a plate clutch

The performance of a plate clutch in a two-inertia power transmission system is analysed assuming negligible compliance and using a piecewise linear function to represent the clutch torque characteristic. Expressions defining, for all linear segments of the clutch torque characteristic, dimensionless input and output velocities of the clutch and dimensionless slip period are presented. The use of these expressions in preparing design charts to aid analysis and design of the plate clutch is outlined.     

新型液压无级变速器的动力仿真与设计改进

应用PRO/E软件建立了该变速器的实体模型,并检测其动、静态干涉情况;应用ADAMS软件建立了该变速器传动系统的仿真模型,并模拟装置在现实环境下的运动,通过仿真测量得到了柱塞的位移、速度、加速度及轴承处支撑反力随时间变化的曲线;最终以理论分析和仿真结果为基础,设计了配重平衡装置及零件结构改进方案。结果表明,该配重装置可大大减缓变速器低速旋转时轴承处支撑反力的波动;柱塞结构的改进可减小变速器高速运转时轴承处支撑反力的波动幅值。     

双传动滚筒动力分析与上料机传动装置设计

针对新高炉上料主胶带机双滚筒传动装置布置形式、动力分析、动力平衡及传动装置进行研究设计,为高炉上料机设计提供帮助。     

全液压飞机牵引车牵引特性分析

根据车辆液压传动系统设计的核心内容,给出全液压式飞机牵引车的参数指标,阐述其发动机与液压泵的功率匹配原理及其液压系统的驱动方式与控制方法,并针对该车的牵引性能进行试验分析,得出了试验结果.     

通用桥式起重机电动机功率的简化计算及校验

<正>由于起重机专业方面的资料很少,在设计计算时主要依据《起重机设计手册》和GB/T3811—1983《起重机设计规范》。在这些资料中对     

广角极光成像仪滤光片的热设计及试验

针对广角极光成像仪对其光学系统温度的特殊需求,对成像仪使用的高温滤光片进行了热设计及相关试验。介绍了广角极光成像仪的光机结构,尤其是滤光片组件的结构。通过建立传导和辐射热阻的计算方程组,分析了由滤光片到镜筒整个换热路径中存在的热阻及其影响因素。然后,以影响热阻的因素作为设计变量,分析了影响镜筒温度的敏感变量。最后,提出了高温滤光片的热设计方案。真空验证试验表明:在高温和低温两种极端工况下,滤光片温度水平分别稳定在105.8℃和138.2℃,其控温准确度优于±2.5℃,控温稳定度优于0.75℃/min;反射镜组和探测器窗口温度水平和温差都满足热控指标。得到的结果显示,基于热阻和温度灵敏度分析的设计方法,能够快速明确影响热阻的敏感设计变量,减少设计过程的盲目性。空间高温滤光片的热设计满足了光学系统的要求,保证了广角极光成像仪滤光片组件与反射镜之间的温差。     

新型多动力源动力耦合装置传动特性研究

多动力源动力耦合装置是混合动力电动汽车、多动力源工程机械及多动力源军用越野车辆必动部件,功率合成模式的动力耦合装置可以实现无冲击的动力合成与切换.文中介绍了由斜齿圆柱齿轮组成、按照功率合成模式工作的新型无齿圈行星齿轮多动力源动力耦合装置的结构;研究了混合动力电动汽车电动机驱动模式、发动机驱动模式的传动比计算;分析了发动机和电动机联合驱动模式的传动特性.     

PTC--打造动力传动与控制领域旗舰展会--访汉诺威展览会(中国)有限公司公关部

亚洲国际动力传动与控制技术展自1991年以来已成功举办了9届，成为同类型专业展览中的品牌展会。为促进动力传动与控制领域的技术进步并扩大国际贸易与交流，秉承了德国汉诺威工业博览会的优良传统的2005 PTC Asia将于11月28日在上海新国际博览中心拉开帷幕。众多行业内知名厂商将同场竞技，展示该领域的最新科技成果。展会将成为行业专家、企业同行及相关媒体共同关注的焦点。作为行业专业媒体，届时我刊将参加此次蛊会，在报道展会实况的同时，还将携手德国汉诺威展览公司在展会现场举办“2005流体机械论坛之——风机、压缩机行业高峰论坛”，旨在为压缩机、风机生产企业和用户行业搭建起交流平台。为了让业内人士对展会的情况有更加明了，本刊记者对展会主办方做了这次采访。[编者按]     

Analysis of rupture instability in the hydromechanical deep drawing of cylindrical cups

This paper presents analyses of tensile instability in the hydromechanical deep drawing process of cylindrical cups. Analytical models are developed based on Barlat-Lian and Hill’s non-quadratic yield criteria and the maximum permissible fluid pressure, above which rupture occurs, is achieved, assuming plane strain tensile failure. The influences of process and material variables on this critical fluid pressure are investigated. The theoretical results are compared with results obtained from experiments to verify the validity of the proposed analytical approaches.     

基于ARM的传感器校验仪GSM数据传输的研究

本文讨论了基于ARM传感器校验仪校验结果,通过GSM模块以短信形式传输的研究方案,依托现有移动通信GSM网络的SMS服务作为数据传输的通道,实现校验数据以短信形式发送上级部门,从而为安全提供了保障。     

载货汽车动力传动系统的优化设计

针对某一载货汽车的性能参数,提出原车整车匹配方面存在的问题。运用GT-DRIVE自带的DOE优化分析功能模块,优化汽车的传动系参数,通过改变主减速器速比和变速器各挡速比,提出了分别以整车动力性、燃油经济性以及权衡整车动力性、燃油经济性为目标的三种优化方案,通过分析结果,合理改变传动系参数,最终达到优化整车性能的目的。     

液压机械复合传动基本特性分析

对单行星排液压机械复合传动进行了详细分析，给出了无级调速特性、功率流特性、循环功率和传动效率等性能参数的计算式以及特性曲线。     

车辆动力传动系的耦合与匹配研究

阐述产品设计耦舍与匹配的概念，提出了车辆动力传动系统匹配的基本内容。包括结构布置、性能、控制和强刚度等4类匹配。以栽重汽车传动系各挡传动比分配为应用示例，建立优化数学模型并求解，得出比原车性能更好的传动比分配结果。     

Vibration characteristics and power transmission of coupled rectangular plates with elastic coupling edge and boundary restraints

Coupled-plate structures are widely used in the practical engineering such as aeronautical,civil and naval engineering etc.Limited works can be found on the vibration of the coupled-plate structure due...     

Increasing the stability of constant-speed hydromechanical systems

A method is proposed for increasing the stability of a constant-speed hydromechanical system developed for ground transportation. The method is based on a dynamic shock absorber in a centrifugal pendulum.