Articulated Lifting System Modeling Based on Dynamics of Flexible Multi-Body Systems

In lifting sub-system of deep-sea mining system, spherical joint is used to connect lifting pipes to replace fixed joint. Based on Dynamics of Flexible Multi-body systems, the mechanics model of articulated lifting system is established. Under the four-grade and six-grade oceanic condition, dynamic responses of lifting system are simulated and experiment verified. The simulation results are consistent with experimental ones. The maximum moment of flexion is 322 kN-m on the first pipe under six-grade sea condition. It is seen that the articulated connection can reduce the moment of flexion. The bending deformation of pipe center is researched, and the maximum is 0. 000479 m on the first pipe. Deformation has a little effect on the motion of system. It is feasible to analyze articulated lifting system by applying the theory of flexible multi-body dynamics. The articulated lifting system is obviously better than the fixed one.

Dynamic Analysis of the Seafloor Pilot Miner Based on Single-Body Vehicle Model and Discretized Track-Terrain Interaction Model

In order to achieve the complex dynamic analysis of the self-propelled seafloor pilot miner moving on the seafloor of extremely cohesive soft soil and further to make it possible to integrate the miner system with some subsystems to form the complete integrated deep ocean mining pilot system and perform dynamic analysis, a new method for the dynamic modeling and analysis of the miner is proposed and developed in this paper, resulting in a simplified 3D single-body vehicle model with three translational and three rotational degrees of freedom, while the track-terrain interaction model is built by partitioning the track-terrain interface into discrete elements with parameterized force dements built on the theory of terramechanics acting on each discrete dement. To evaluate and verify the correctness and effectiveness of this new modeling and analysis method, typical comparative studies with regard to computational efficiency and solution accuracy are carried out between the traditional modeling method of building the tracked vehicle as a multi-body model and the new modeling method. In full consideration of the particMar structure design of the pilot miner, the special characteristics of the seafioor soil and the hydrodynamic force of near-seafloor currnt, the dynamic simulation analysis of the miner is performed and discussed, which can provide useful guidance and reference for the practical miner system in design and operation. This new method can not only realize the rapid dynamic simulation analysis of the miner but also make possible the integration and rapid dynamic analysis of the complete integrated deep ocean mining pilot system in further researches.

Model Based Adaptive Control and Disturbance Compensation for Underwater Vehicles

Underwater vehicles are being emphasized as highly integrated and intelligent devices for a significant number of oceanic operations. However, their precise operation is usually hindered by disturbances from a tether or manipulator because their propellers are unable to realize a stable suspension. A dynamic multi-body model-based adaptive controller was designed to allow the controller of the vehicle to observe and compensate for disturbances from a tether or manipulator. Disturbances, including those from a tether or manipulator, are deduced for the observation of the controller. An analysis of a tether disturbance covers the conditions of the surface, the underwater area, and the vehicle end point. Interactions between the vehicle and manipulator are mainly composed of coupling forces and restoring moments.To verify the robustness of the controller, path-following experiments on a streamlined autonomous underwater vehicle experiencing various disturbances were conducted in Song Hua Lake in China. Furthermore,path-following experiments for a tethered open frame remote operated vehicle were verified for accurate cruising with a controller and an observer, and vehicle and manipulator coordinate motion control during the simulation and experiments verified the effectiveness of the controller and observer for underwater operation. This study provides instructions for the control of an underwater vehicle experiencing disturbances from a tether or manipulator.

Earth system multi-body restriction dynamics model research

Research provides a theoretical basis for an Earth system multi-body mechanics model and its dynamics, including the Earth system multi-body restriction function and its power, Earth system multi-body restriction under decreasing generalized velocity and decreasing partial palstance, the Earth system multi-body decreasing generalized force, a moving mechanics function, and the Earth system multi-body restriction's wattful and wattless forces.

An Earth multi-body system elasticity and plasticity dynamics model

Research on the elasticity and plasticity dynamics of the Earth multi-body system, including the Earth multi-body system stratum-block's equivalent inertia force system and generalized inertia force, the Earth multi-body system stratum-block's equivalent inertia force system expressed with partial velocity and partial palstance, and Earth multi-body system generalized inertia force expressed with partial velocity and partial palstance. This research provides a theoretical foundation for further investigation of Earth multi-body dynamics.

Multi-body dynamics modeling and test of an articulated steering half-track tractor

With the benefits of small turning radius and high trafficability, the articulated steering half-track tractor had been widely utilized in orchard and small spaced farmland. To study the dynamic performance of the articulated steering half-track tractor and provide a model basis for studying the path tracking control, an accurate multi-body dynamic model of the tractor was required. In this study, the crucial parameters in the dynamic model construction of the tractor were investigated. Firstly, the topology model of the components of the half-track tractor was built by RecurDyn, in which the movement subs and driver functions were given. Secondly, considering the difference of dynamic characteristic of the articulated steering tractor with respect to different pavement hardnesses, the soft and hard pavement models were constructed by employing the harmonic superposition method. Finally, the simulations of the half-track tractor under straight-line and swerve had been conducted on the two types of pavements, and the simulation results were compared with the experimental and theoretical results. The results indicated that the average speed error of the dynamic model on hard pavement and farmland soft pavement were 2.7% and 2.1% compared with the real tractor tests. At the same time, the straight-line driving offset errors of the dynamic model on the two pavements were 1.6% and 3.8% for the front wheels and the rear wheels offset errors were 3.9% and 2.4%, respectively. Furthermore, the turning radius error under front wheel steering was 8.2% and the error under articulated steering was 5.3%. It is proved that the established dynamic model had high accuracy, which provides an efficient approach to analyze the dynamic features of the half-track tractor.

基于动态磨损模型的汽车覆盖件模具磨损数值模拟研究

针对某铝合金覆盖件冲模磨损失效问题,为更加准确地预测汽车覆盖件模具的使用寿命,基于Archard磨损模型建立了动态磨损模型。该模型耦合了动态磨损系数和表面硬度变化曲线,其中,磨损系数K转化为随接触压力和相对滑移速度变化的动态磨损系数,表面硬度考虑了磨损深度的变化。利用Python语言对ABAQUS软件进行二次开发,将动态磨损模型耦合到有限元模拟中,实现了考虑磨损系数和硬化层深度变化的汽车覆盖件模具磨损计算。通过对比分析凸凹模典型位置在成形过程中的动态磨损演化规律,并以模具最大磨损深度0.5 mm作为失效判据,得到该铝合金覆盖件冲压模具的使用寿命为635428次。模具主要发生磨损的位置集中在模具合模线附近和大圆角处,在实际生产中需要对这些位置进行修模、调试,从而有效延长模具的使用寿命。

低碳技术创新、区域经济发展对汽车业碳排放的影响机制研究

为了探究低碳技术创新、经济发展对汽车业碳排放的影响,基于我国新能源汽车较为普及的7个省市2013—2020年的数据,采用静态面板模型和动态面板模型,细致分析低碳技术创新、区域经济发展对汽车业碳排放量的影响,并通过分样本回归检验低碳技术创新、经济发展对燃油车碳排放和新能源车碳排放的异质性影响。研究表明:低碳技术创新对汽车业碳排放量有显著负向影响,区域经济发展对汽车业碳排放量有显著正向影响;汽车业碳排放具有延续性特征,受前期排放量的影响较大;低碳技术水平的进步可以更有效地促进燃油车的碳减排,而经济发展水平的提高则会更显著影响新能源汽车的碳减排。

基于CFD的某特种电动汽车空气动力学分析与改进设计

为降低某特种电动汽车空气阻力,对其车身造型进行了改进设计。对初始设计的汽车模型进行CFD外流场仿真分析,得出其风阻系数为0.4173,车顶前端、前窗和尾部等有明显的涡流。选择车顶倾斜角α(1)、前窗玻璃角α(2)、前唇倾角α(3)、后背角α(4)和尾部上翘角α(5)为设计变量,仿真分析车身外形局部结构参数对汽车气动特性的影响,并提出了改进设计方案。仿真结果表明:改进后车身升力系数的绝对值为0.1141,相对初始设计提高了41.92%;风阻系数为0.3937,相对初始设计降低了5.66%,有效改善了汽车的气动特性,提升了其续航能力。

汽车发动机冷却系统参数匹配性设计分析

冷却系统匹配性直接影响到系统的散热效率,进而影响发动机的工作效率和经济性。根据工程车辆发动机冷却系统的结构特点,对冷却风量、散热量、水泵参数及系统匹配进行分析;基于分析情况,对某车型发动机的散热器和风扇参数进行设计,对匹配工作点参数进行分析;应用发动机冷却系统测试平台,对匹配设计参数进行测试,获取额定运行工况下,发动机散热器各进出水口的温度变化情况,以此验证匹配设计的准确性。结果可知:系统阻力随冷却空气流量增加而增大,与风扇特性曲线的交点,即为系统的平衡点,位于风扇曲线的稳定区和高效区。交点对应的空气流量为设计参考值;参数分析得到,车辆设计中标出点的空气流量约为14.1kg/s,静压约为850Pa,效率为36%;冷却系统经过840s,散热器各进出水口达到稳定状态,中冷散热器进出口温度为68.5℃、58.9℃;高温散热器进出口温度为85.5℃、74.9℃,满足发动机的散热需求。结果表明匹配分析的准确性,为此类设计提供参考。

Research on the Earth system multi-body force system dynamical model

This paper presents an overview of the binding force and freedom force of Earth system, and describes force moment to point and line and force system in the Earth system. It introduces the force theory of the Earth system multi-body force system from special or equivalent force system of Earth system mechanics, general force and no-power force of Earth system. Finally it describes the force and moment of nodes of Earth system and provides basic model for the research of the Earth system multi-body dynamics.

Manual Transmission Gear Rattle Vibration Research Based on Mathematical and Multi-Body Dynamics Co-simulation and Experiment

A method, which compares the angular acceleration and vibration spectrums of shafts and gears with physical characteristics of gearbox as tooth numbers and speed ratios, is proposed to find the source of gear rattle vibration. A mathematical and multi-body dynamics co-simulation model is built to reproduce the gear rattle phenomenon of one typical type of manual transmission. In the model, multi-body dynamics part is used for rotational motion and engagement simulation of gearbox shafts and gears, while mathematical part for control and data processing. The simulation results show that the sound source of the gear rattle from the first gear to the third gear is similar to the experimental results;different parameters like rotating damping, contact stiffness,contact damping, inertia moment and torque fluctuation making effects on gear rattle vibration strength are researched and simulated. The comparison of the simulation and experimental results shows that this method can provide recommendations for solving practical gear rattle problems.

基于汽车系统动力学的虚拟驾驶仿真模型研究

基于汽车系统动力学建立了一种包括发动机模型、传动系模型、离合器模型、制动系模型、汽车行驶速度模型、转向系模型的仿真模型。基于以上模型开发的汽车虚拟驾驶仿真系统可以准确地模拟汽车在起步、加速、转向以及制动等各种行驶工况的状态以及汽车的各种动力学响应。以上模型为汽车虚拟驾驶仿真系统提供了完整的汽车系统动力学模型,同时,该模型也可进一步应用于汽车的数字化设计,检验汽车的动力学性能。

汽车车身结构动力学建模方法研究

基于汽车车身结构中点焊连接界面的特性，提出了其动力学建模的简化原则，并以依维柯轻客车为对象，建立了车身结构的有限元模型， 其动态分析结果显示与车身在运行中的状态特征是一致的， 证明了所建车身动力学模型的正确性， 这为今后新车身开发打下了良好的技术基础。

汽车尾迹涡的形成及其控制

绕汽车的流场在其尾部形成非常复杂的的尾迹。本文通过大量试验研究,对尾迹中旋涡形成的机制归纳为以下几种动态仿真理论模型,即涡量注入模型、剪切层相互作用模型、涡列有限涡核稳定模型、二次分离涡振荡模型及尾流绝对不稳定模型。在此基础上研究了控制上述尾迹旋涡结构和抑制涡激振动的方法。

ADSL驾驶模拟器动力学模型的改进与验证

为了提高ADSL驾驶模拟器逼真度,研究开发了新版转向系统模型、车轮模型、制动系统模型.转向系统模型为力输入模型并计算了系统的弹性;车轮模型考虑了气胎弹性、接地印迹块动力学和接触模型;制动系统模型采用制动力矩动静摩擦分离的计算方法;从而实现了左右转向车轮协调计算、轮胎力准确计算及stand-still(起步-停车)工况、制动到零速等精确工况的仿真.通过新版模型、2000年版模型的操纵稳定性工况的仿真结果与场地试验结果的对比,验证了模型的正确性,模型精度得到了提高.

汽车再生资源利用系统建模分析

通过对汽车产品生产、销售、使用、报废、回收及再利用过程的全寿命周期的资源利用过程分析,确立了汽车再生资源利用系统各变量之间的因果关系;利用系统动态学方法建立了汽车再生资源利用系统流图,并构建了汽车再生资源利用系统数学模型;以此模型为基础对我国汽车报废量进行了预测;通过仿真对影响汽车再生资源总量变化的因素进行了分析,从而为汽车再生资源的合理利用及相关政策制定提供了可借鉴的理论方法。

车辆安全行驶动态仿真模型及应用研究

针对智能车主动安全系统中安全建模、实时求解等问题,根据车辆行驶速度与车距两个重要的安全因素,将汽车安全行驶的及时感知(检测)和处理(驾驶)分解为与速度相关的时间量,提出了汽车安全行驶仿真动态模型P2OT(环境感知、决策、驾驶操作、汽车行驶)及其时间表达式。应用分析及实验结果说明本文所讨论方法是可行的,具有实际应用价值。

时域和空间域路面激励下重型车辆动载荷仿真分析

为研究时间和空间频率路面激励下重型车辆动载特性,将车辆的轮胎、钢板弹簧视为柔体,橡胶垫块、限位块简化为具有非线性刚度和阻尼特性的力元,采用多体动力学仿真软件SIMPACK建立刚柔耦合的车辆整车虚拟样机,并采用有理函数功率谱密度的谐波叠加法建立空间域和时域路面激励数学模型,创建一个时域和空间域路面激励下车辆行驶动力学模型,仿真计算了车辆各轴轮胎的法向作用力和车轮法向动载系数。结果表明:不同车速下,时域和空间域路面激励下得到的轮胎法向作用力的变化规律和大小均不相同,而且轮胎法向作用力最大值出现的位置也不同;中、后轴车轮法向动载系数变化规律基本相似,但前轴车轮法向动载系数变化规律不同。研究结果可为轮胎动载荷计算、验证、预测提供参考依据。

混合动力汽车匀速下坡再生制动模型预测控制

基于车载导航系统(GPS/GIS等)所提供的未来一段预测路线上的汽车运行状态信息,建立中度混合动力汽车再生制动能量回收的全局优化动态规划模型;采用模型预测控制方法,将动态规划的全局优化控制策略转化成预测视距内的局部优化算法,实现滚动优化控制;为解决动态规划中的维数灾问题,确定了电池荷电状态和温度的可达区域;对模型预测控制策略、全局优化控制策略和瞬时优化控制策略进行了计算比较,在不同坡度、不同坡长的匀速下坡工况下的仿真表明:模型预测算法的计算效率显著高于全局优化策略的;应用模型预测控制策略的再生制动能量回收效率明显高于瞬时优化控制策略的,相比全局优化策略的降低不到1.31%,且采用档位提示的模型预测控制策略能量回收效果更好。