Solving Nonlinear Differential Equation Governing on the Rigid Beams on Viscoelastic Foundation by AGM

In the present paper a vibrational differential equation governing on a rigid beam on viscoelastic foundation has been investigated. The nonlinear differential equation governing on this vibrating syst...     

Д形圆柱体大角度撞水载荷计算及缓冲问题的研究

一种Д形圆柱体底部金属结构在大角度高速入水时遭受破坏,解决该问题对某工程活动具有重要意义。根据KornhauserM提出的数学模型,对该圆柱体入水载荷进行预报计算并对缓冲问题进行分析,提出了在不改变Д形圆柱体结构的情况下,使用硬质聚胺酯泡沫塑料(RPUF)作缓冲层的方案,解决了工程中遇到的难题。     

串联刚度对液压减振器特性的影响

液压减振器在铁路机车车辆上被看成是一个减振器(阻尼)和端部橡胶元件(刚度)相串联的组合部件,串联刚度对机车车辆动力性能有着较大的影响。文章讨论了串联刚度对减振器特性的影响,还介绍了减振器性能的测试方法和动力学计算中的减振器模型。     

车体弯曲振动减振法

从乘坐舒适度方面看,车体弯曲振动的减振措施主要针对车体本身,本研究包括了转向架。车体与转向架间采用的牵引装置等的参数对车体影响很大,优化这些参数对减小弯曲振动是有效的。     

Smoothing dry friction damping by dither generated in rolling contact of wheel and rail and its influence on ride dynamics of freight wagons

Friction dampers of mechanical systems are frequently exposed to medium-frequency (M-F) dither generated in the surrounding environment. A dithered system of technical importance is the railway freight wagon with friction dampers in the primary suspension developing two-dimensional friction, where dither is generated by the rolling contact of wheel and rail. This paper presents some results of the investigation of the influence of dither on dry friction damping. This influence has been studied experimentally and theoretically, and the parameters of dither influencing dry friction damping have been indicated. An experimental set-up has been designed that allows investigating friction damping in the presence of dither. The experiments have shown that friction damping in the presence of the M-F dither behaves like viscous damping. This means that dither smoothes dry friction as far as damping is concerned. To investigate this phenomenon theoretically, a rheological model of dry friction has been proposed that is applicable to one- and two-dimensional friction. In the latter case, the model takes into account friction anisotropy. According to performed numerical simulations of freight wagon motion, with dither supplied to the model through measured vertical accelerations of axle boxes, smoothing dry friction by dither strongly influences ride dynamics of the wagon with friction dampers in the primary suspension. Smoothing dry friction by dither should be accounted for in numerical simulations of motion of vehicles with friction dampers in the primary suspension by employing a proper model of the two-dimensional friction and application of realistic dither generated by rolling contact.     

基于加速度阻尼控制的半主动悬挂研究

半主动悬挂是改善铁道车辆振动、提高乘坐舒适度的有效对策。但由于铁道车辆的特殊性和复杂性,车辆动力学系统的精确数学模型很难获得,这限制了现代控制理论在实用化半主动悬挂中的应用;而天棚阻尼控制所需车体的绝对速度很难测量,若采用测得车体加速度积分得到车体绝对速度的方法,其传感器的误差和系统噪声会导致车体绝对速度产生误差,从而影响减振效果。基于上述原因,本文提出加速度阻尼控制方法,即采用与车体加速度成正比的振动衰减力来抑制车体振动,并对加速度阻尼控制方法稳定性进行理论分析和仿真研究。仿真结果证明:与被动悬挂相比,车体振动加速度有效值和最大值在各速度级分别减少了55%~63%和53%~66%,Sperling乘坐指数也得到明显改善;且加速度阻尼控制具有很好的鲁棒性和适应性。可见该方法能有效地提高铁道车辆的平稳性和乘坐舒适性。     

MATLAB软件在RLC阻尼振荡电路分析中的应用

在电路分析中经常会遇到阻尼振荡电路,由于这类电路在高压断路器开断能力测试、受控热核研究等许多重要的工程领域有着极为广泛的应用,因此有必要对此类电路的特性加以讨论研究。本文介绍了RLC振荡电路建立数学模型的方法,利用时域中传统的微分方程法和频域中经典的拉普拉斯变换法对电路进行了分析,借助MATLAB软件对一类RLC电路的过渡过程进行了仿真分析,并对其产生的误差作出了一定的解释。     

Roll stabilisation of road vehicles using a variable stiffness suspension system

A variable stiffness architecture is used in the suspension system to counteract the body roll moment, thereby enhancing the roll stability of the vehicle. The variation of stiffness concept uses the ‘reciprocal actuation’ to effectively transfer energy between a vertical traditional strut and a horizontal oscillating control mass, thereby improving the energy dissipation of the overall suspension. The lateral dynamics of the system is developed using a bicycle model. The accompanying roll dynamics are also developed and validated using experimental data. The positions of the left and right control masses are sequentially allocated to reduce the effective body roll and roll rate. Simulation results show that the resulting variable stiffness suspension system has more than 50% improvement in roll response over the traditional constant stiffness counterparts. The simulation scenarios examined is the fishhook manoeuvre.     

磁流变阻尼器对建筑结构地震响应半主动控制分析

研究目的:地震时建筑结构的大幅震动已为世人关注。国外学者将磁流变(MR)阻尼器应用到土木结构震动控制上,效果较好。为扩大其在实际工程中的应用,进一步对磁流变阻尼器对建筑结构地震响应进行了理论分析和试验。研究方法:本文首先通过磁流变阻尼器的构件参数(如:活塞的有效长度、缸体的内径、活塞直径、流体的粘度系数等)、输入电流及阻尼器活塞相对于缸体简谐运动频率的改变,分析了各参数对阻尼特性的影响,这将为设计阻尼特性较好的磁流变阻尼器提供理论依据。然后采用了磁流变(MR)阻尼器的修正Bouc-Wen模型及剪切型最优控制(Clipped-Optimal Control)算法对建筑结构地震响应进行了半主动控制分析研究,并且与结构被动控制的效果进行了对比。研究结论:在EI-centro地震激励作用下,被动控制和半主动控制对结构地震响应的水平位移与速度产生了不同的控制效果;对结构的位移及速度的控制效果,MR半主动控制均明显地优于被动控制。     

粘弹性线性复合结构动力特性分析

本文采用Ｖｏｉｇｅｔ－Ｋｅｌｖｉｎ粘弹性材料力学模型和等参元法，推导了约束阻尼层单元的刚度阵，并应用逐次逼近求解粘弹性线性复合结构特征值，讨论和分析了结构边界条件，结构刚度以及阻尼处理面积和位置对复合结构动力特性的影响，获得了一些具有工程应用价值的结论。