无砟轨道减振垫层刚度-阻尼匹配设计分析

随着高速铁路路网的不断加密,线路不可避免穿越环境敏感区,由列车运行所引起的振动问题日益严重。目前常采用减振垫层进行振动控制,但其参数取值大多从单一角度考虑,缺乏协调设计,导致减振效果不佳。为探究减振垫层刚度与阻尼合理匹配设计值,在有限元中建立车辆-减振轨道-下部结构耦合模型,利用显示动力学分析不同减振垫参数组合值下轨道结构动力响应,通过规范限值剔除极端工况,利用加速度振级、传递损失、插入损失对不同参数组合值下的减振性能进行全方位、多角度分析。结论如下:(1)轨道各结构动力响应满足规范限值要求时,减振垫层刚度应不小于60 MPa/m,阻尼不小于0.1 MN·s/m^(3);(2)减振效果总体上与刚度呈负相关趋势,在减振垫层刚度-阻尼组合值分别为60 MPa/m、0.1 MN·s/m^(3)与100 MPa/m、0.1 MN·s/m^(3)时,底座板动力响应较小;(3)从传递损失角度出发,减振垫层可有效削弱轨道中、高频段振动能量,从插入损失角度出发,虽然垫层会放大某些低频振动,但对中、高频段减振效果较好,对比后取减振垫层刚度-阻尼组合值为100 MPa/m、0.1 MN·s/m^(3)。研究结果表明,对减振垫参数进行协调设计可最大发挥其减振性能。

非线性油气悬架的阻尼特性研究

以矿车后悬的油气悬架为研究对象,利用统计线性化的方法,按照等效线性阻尼系数相等的原则,计算出了渐增、线性和渐减3种阻尼模型的参数.在稳态随机路面的激励下,利用Matlab/Simulink仿真并比较非线性刚度与3种阻尼模型匹配时的车身加速度均方根值、悬架动行程、车轮动载荷以及减振器的发热功率,得到了不同类型阻尼对上述指标的影响,对阻尼的匹配、优化设计具有参考价值.

复合材料螺旋桨流固耦合振动噪声研究综述

为了全面梳理有关复合材料桨的研究内容和方法,指出研究方向和思路,本文从稳态流固耦合变形、瞬态流固耦合振动和噪声等方面,综合国内外对弹性水翼和复合材料螺旋桨的研究进展进行了分析。国外在复合材料螺旋桨的流固耦合理论研究、测试技术等方面较为先进,可以将高阻尼材料通过完善的工艺成型方式应用于舰船螺旋桨。而国内对复合材料螺旋桨的稳态流固耦合变形研究较多,对瞬态流固耦合振动和噪声研究较少,没有形成完善的复合材料螺旋桨理论研究和测试体系,在实船应用方面更是空白。在此基础上,提出了复合材料螺旋桨减振降噪机理和刚度阻尼匹配设计方法的研究前景。

叉车振动仿真及发动机总成悬置优化

利用ADAMS软件建立某型叉车整车在怠速工况下的振动仿真模型,并进行实验验证,实验表明通过采用对连接螺栓的柔性化方法可以有效提高叉车仿真模型的准确性。在此基础上利用ADAMS试验设计方法,对整车动力总成悬置刚度阻尼匹配进行优化,结果表明通过刚度阻尼的合理匹配能在一定程度上改善整车车架上的振动情况。

Stiffness-damping matching method of an ECAS system based on LQG control

A novel method of matching stiffness and continuous variable damping of an ECAS(electronically controlled air suspension) based on LQG(linear quadratic Gaussian) control was proposed to simultaneously improve the road-friendliness and ride comfort of a two-axle school bus.Taking account of the suspension nonlinearities and target-height-dependent variation in suspension characteristics,a stiffness model of the ECAS mounted on the drive axle of the bus was developed based on thermodynamics and the key parameters were obtained through field tests.By determining the proper range of the target height for the ECAS of the fully-loaded bus based on the design requirements of vehicle body bounce frequency,the control algorithm of the target suspension height(i.e.,stiffness) was derived according to driving speed and road roughness.Taking account of the nonlinearities of a continuous variable semi-active damper,the damping force was obtained through the subtraction of the air spring force from the optimum integrated suspension force,which was calculated based on LQG control.Finally,a GA(genetic algorithm)-based matching method between stepped variable damping and stiffness was employed as a benchmark to evaluate the effectiveness of the LQG-based matching method.Simulation results indicate that compared with the GA-based matching method,both dynamic tire force and vehicle body vertical acceleration responses are markedly reduced around the vehicle body bounce frequency employing the LQG-based matching method,with peak values of the dynamic tire force PSD(power spectral density) decreased by 73.6%,60.8% and 71.9% in the three cases,and corresponding reduction are 71.3%,59.4% and 68.2% for the vehicle body vertical acceleration.A strong robustness to variation of driving speed and road roughness is also observed for the LQG-based matching method.