液压传动中管道非恒定流动的各相压力值

本文利用“联锁方程”来解决液压冲击的计算问题,与传统的经验公式相比,其特点是:可方便地计算出直接冲击和间接冲击的物理量;能计算出液压间接冲击的各相压力值;计算液压冲击问题时,物理概念清晰,便于加深对液压冲击内在机理以及各物理量之间变化规律的理解。     

制动力液压传力装置的节流特性研究

论述了设置液压传力装置的铁路桥梁随温度变化和制动力作用的墩顶位移对节流量的限定条件，分析确定了不同桥长的节流量范围。通过对实验液压装置的节流特性研究，提出了节流量的测试方法和选用节流阀的推荐旋口度，完成了铁路桥梁采用液压传力装置的技术可靠性论证。     

船舶综合液压推进工况配合特性研究

随着船舶向大型化、高速化方向发展,多主机并联工作模式随之出现.目前有采用电力推进以及机械推进方式来设计的,但机械传动与电力传动设备的功率重量比远小于液压传动,文中提出船舶综合液压推进.根据其推进原理绘制其工况配合特性曲线,通过该配合特性曲线图对其设计工况以及非设计工况配合特性进行了分析探讨,结果表明船舶综合液压推进具有"轻载高速,重载低速"的特点,适合于大功率船舶、工程船以及特种船舶.     

液压负载传感调速系统

液压负载传感调这具有节省功率和减少系统发热量等优点。其主要原理晃使泵根据换向控制阀口的大小而提供相应的流量，变节流调速为容积调速，从而达到最佳调速之目的。     

矿用汽车盘式制动器的设计与分析

根据矿区作业环境及满足车辆制动力矩需要选择前轮盘式制动器,通过收集关于制动器要求数据,确定选用钳盘式制动器,且制动钳装在盘后方。该制动器装有液压轮缸,通过液压作用推动制动块的摩擦力阻止制动盘运动,从而制止传动轴运动,达到制动效果。通过设计合适的感载比例阀以及ABS系统来调节制动力大小,防止车轮抱死。     

永磁同步交流伺服电动机多领域建模与仿真

多领域物理系统建模仿真技术是将机械、电子、液压、控制等不同学科领域的模型组装成为一个可以协同仿真的耦合仿真系统模型.在分析永磁同步交流伺服电动机结构与驱动控制原理的基础上,结合基于Modelica语言多领域建模原理对其进行多领域建模与仿真分析.建模与仿真过程中,对电机运动规划采用机器人常用的PTP运动规划,控制器控制方法采用PI控制.通过多领域建模与仿真分析,电机能够基本按照PTP运动规划进行运动,从而为后续的机器人仿真、数控机床仿真等提供基础.     

振动压路机振动液压系统吸空问题分析

对振动压路机振动系统闭式液压回路原理进行分析,得出停振时液压系统容易产生高压腔吸空问题的原因。提出通过延长停振时间和增加补油量来解决液压系统吸空的措施,同时,给出了在补油回路增设低压蓄能器来抑制发生吸空问题的方案。     

直齿圆柱齿轮副动力学特性分析

利用拉格朗日方程建立了含间隙直齿圆柱齿轮副的动力学模型,通过齿轮轮齿弹性变形的原理数值计算建立了时变刚度的数学模型.利用4~5阶Runge-Kutta数值积分法对系统进行了数值求解.结合Poincaré映射图、相图、FFT频谱图、系统分岔图分析了系统随激励频率和阻尼变化时的动力学行为,发现了其稳定周期运动和倍周期运动及混沌运动.通过齿轮冲击模型数值计算,找出了不同初值情况下的冲击状态.     

基于AMESim的甘蔗收割机液压系统建模与仿真研究

通过简要介绍甘蔗收割机类型和主要结构,设计出了小型整杆式甘蔗收割机的液压系统。对该液压系统的闭式行走系统的控制特点和DA阀工作原理进行了分析;对开式工作装置液压系统中采用的LUDV负荷传感控制系统的控制原理及优点进行了分析;并利用AMESim软件对部分执行机构进行建模仿真。仿真结果表明:LUDV负荷传感控制系统符合机器的工作要求。     

压力反馈控制液压夯拔装置的性能分析

对液压夯拔装置的性能进行了分析,提出了通过立柱阻力适时调节系统的冲击压力,可实现冲击能和冲击频率的独立无级调节.     

Numerical modeling of dual-pulse shock test machine for simulating underwater explosion shock loads on warship equipments

In order to qualify shock resistance performance of shipboard equipments and simulate real underwater explosion environment, a novel dual-puise shock test machine is proposed. The new machine will increase testing capability and meet special shock testing requirement. Two key parts of the machine, the velocity generator and the shock pulse regulator, play an important role in producing the positive acceleration pulse and the succeeding negative acceleration pulse, respectively. The generated dual-pulse shock for test articles is in conformity with an anti-shock test specification. Based on the impact theory, a nonlinear dynamic model of the hydraulically-actuated test machine is established with thorough analysis on its mechanism that involves conversion of gas potential energy and dissipation of kinetic energy. Simulation results have demonstrated that the proposed machine is able to produce a double-pulse acceleration shock in the time domain or a desired shock response spectrum in the frequency domain, which sets up a base for the construction of the machine.     

Numerical Simulation Research on Laser Shock Forming of Thin Metal Sheet

Laser shock forming (LSF) of sheet metal is a new technique realized by applying an impulsive pressure generated by laser-induced shock wave on the surface of metal sheet.LSF of brass sheet metal was investigated using a Q-switched Nd:YAG laser with an energy per pulse of 15～50 joules.ABAQUS software was used to simulate laser shock forming process.The central displacement of the shocked region is measured and compared with the simulation.The higher pulse energy, the higher central displacement of the shocked region were obtained.The deformation of the simulation matches the experiment quite well.     

高速交通中堵塞形成阶段的交通流模型

研究了高速交通中由于各种交通瓶颈而导致交通堵塞的过程，通过与高速空气动力学中的激波问题作比拟，建立适用于这一过程的交通流模型，包括完全堵塞和部分堵塞两种状态下的不同模型。依据实际测量数据，论证了平面交叉口绿灯转红灯时车流堵塞波的推进速度满足正态分布假设，其拟合优度高于泊松分布假设。建立的完全堵塞状态下的交通流模型揭示，随着上游来流的平均流量增加，堵塞波的推进速度呈指数规律上升，堵塞前后交通状态指数改变值在O．02～O．30范围内。根据部分堵塞状态下的交通流模型，又可以得到不同程度堵塞条件下，堵塞波的推进速度与上游来流流量之间的定量变化规律，可以作为控制上游来流流量，以减缓堵塞发展或尽快消除堵塞的计算依据。     

冲击压实技术在路基工程中的应用

冲击压实机是具有高冲击能量的压实机械,它将振动压实的高频率低振幅改为高振幅低频率。在牵引机拖动下,周期性地冲击地面,产生强烈的冲击波,向地下深层传播,具有地震波的传递特性。并对冲击压实的作用原理,压实功效以及冲击压实在填石路基中的应用作了介绍。     

Comparison on hydraulic characteristics between orifice plate and plug

Orifice plate energy dissipater as well as plug energy dissipater, as a kind of effective energy dissipater with characteristics of simple structure, convenient construction and high energy dissipation ratio, has become welcomed more and more by hydraulics researchers. The two kinds of energy dissipaters with sudden reduction and sudden enlargement forms are similar in energy dissipation mechanism, but there are differences in energy dissipation characteristics and cavitation characteristics. In the present paper, the differences between orifice plate and plug in energy loss coefficient, relating to their energy dissipation ratio, in the backflow region length, relating to their energy loss coefficient, and in the lowest wall pressure coefficient, relating to their cavitations risk, were analyzed by numerical simulations and physical experiment, and their features in above three aspects were also revealed. The results of research in the present paper demonstrate that the backflow region length of orifice plate is longer than that of plug at the same contraction ratio, the lowest wall pressure coefficient of plug is smaller than that of orifice plate at the same contraction ratio, and the energy loss coefficient of orifice plate is bigger than that of plug, which illustrates that plug is superior to orifice plate in resistance cavitation damage at the same contraction ratio.     

减振器阻尼特性仿真及结构参数影响分析

减振器阻尼特性对车辆平顺性和操纵稳定性有着重要影响。通过对一种双缸式减振器液力系统进行分析,应用液压流体力学理论建立了其数学模型,在MATLAB/Simulink中搭建了减振器仿真模型并进行仿真,其仿真结果与实验结果符合较好。在此基础上利用该减振器仿真系统分析了减振器几个结构参数对减振器阻尼特性的影响,以指导减振器的设计从而较快地获得最合适的结构参数和最优的阻尼特性。     

基于冲击模拟台的减振器冲击特性测试

针对落锤冲击试验的不足,提出了减振器冲击特性的模拟台测试方法.采用该方法对钢丝绳减振器进行测试,并与静、动态特性参数进行比较,从而进一步研究了钢丝绳减振器的特性规律.相比落锤冲击试验而言,本测试方法符合冲击隔离原理,因而测试结果对于工程应用具有更好的参考价值.     

Experimental Investigation of a Single-Stage Four-Valve Pulse Tube Refrigerator

In order to simplify the structure of the cold end of the pulse tube refrigerator (PTR) and have a better utilization of the cold energy of the system, a one-stage four-valve pulse tube refrigerator (FVPTR) with an "L" type pulse tube structure and two orifice valves at the hot end of pulse tube has been constructed. Verification experiments show that the two orifice valve structure performs better than one orifice valve structure. A lowest temperature of 67.5 K was obtained at a frequency of 2.5 Hz under a system average pressure of 1.5 MPa with 200 mesh bronze screens as regenerator material, 80 mesh copper screens as stuffing material of heat exchanger. Due to the difficulty in manufacturing the thin "L" type pulse tube, the wall thickness of the pulse tube in the experiment was relatively difficult for us to reach 0.5 mm as that of the ordinary pulse tube, which resulted in relatively big system loss and affected the minimum temperature of the system to some degree.     

水下非接触爆炸作用下浮动冲击平台运动响应试验研究

对于浮动冲击平台在水下非接触爆炸作用下的冲击响应进行了测量、分析.采用NI公司的采集机及PCB传感器对平台结构的冲击响应（速度、加速度、位移、自由场压力、应力）进行测试,得到不同爆距、平台结构的数值,分析了药量、爆距、平台结构（等爆炸因子）对冲击响应的影响,结果表明：爆距对冲击响应的影响呈非线性变化,结构对冲击响应值影响很大.     

广义势及非惯性系中的Lagrange方程

本文从动能出发,定义一系列惯性力所对应的广义势,获得非惯性坐标系中的Lagrange函数,从而将Lagrange方程推广到非惯性系,为相对运动的研究提供直捷方便的方法。