子系统参数对双层隔振系统隔振特性的影响

为了阐明子系统参数对双层隔振系统隔振特性的影响, 建立了针对带子系统的双层隔振系统的三自由度动力学模型; 推导了一、二级主系统与子系统振幅比的解析式; 分析了3种振幅比随子系统质量比、固有频率比和阻尼比的变化规律; 给出了子系统充当双层隔振系统吸振器时最优参数的解析解和数值精确解; 以中国首批内燃动车动力包为研究对象, 探讨了散热器子系统的刚度、阻尼和质量对动力包双层隔振系统隔振性能以及柴油发电机组和散热器本身振动烈度的影响规律; 得到了最优散热器隔振器刚度的动力包双层隔振系统样机, 并进行了振动试验。试验结果表明: 散热器隔振器刚度大于拐点处刚度1.5倍会严重恶化子系统的振动情况, 其阻尼损耗系数取0.24左右能有效抑制双层隔振系统力传递率和振动烈度比的峰值, 取较大的散热器质量能有效提高双层隔振系统的隔振性能, 减小机组和散热器本身的振动烈度; 经过设计后, 停机工况下二级隔振器最大动反力减小50%, 常规工况下二级隔振器的实测最大动反力为296N, 优于同类水平, 常规工况下机组与散热器实测振动烈度最大值分别为15.45、4.97mm·s^-1, 水平优秀。可见, 取较大的子系统质量和阻尼, 并将其视为双层隔振系统的吸振器进行优化设计, 可使双层隔振系统在柴油机启停机工况和常规工况下都具备较优的动力学性能。     

简支梁桥顺桥向地震动分析

为了计算多跨简支梁桥地震荷载, 根据弹性地基上桥墩的变形特性, 将墩顶作用单位集中力时, 桥墩静力挠度曲线方程作为基本振型, 考虑了地基变形的影响, 利用拉格朗日方程推导了多跨简支梁桥顺桥向地震振动方程, 给出了相应的基频和振型参与系数的近似计算公式。仿真计算结果表明: 简支梁桥一、二阶自振频率的计算值分别为7.43及11.19 Hz, 而其试验值分别为7.00及10.55Hz, 其误差在5.8%以内。可见, 提出的振型可以用于简支梁桥顺桥向的抗震性能评估。     

公路村镇路段横向隔离设施效果评价

选取栅栏式和花池式两种典型的路侧隔离设施,基于路段交通冲突率理论,分别对其隔离效果进行定量分析。结果表明:栅栏式和花池式路段冲突分别降低77%和50%。     

铁路车辆垂向减振与悬挂系统参数优化

为了优化铁道客车垂向悬挂系统参数的选取,建立了铁道客车垂向悬挂系统广义鲁茨卡（Ruzicka）隔振模型,研究其简谐隔振特性,应用评价函数法,对铁道客车垂向悬挂系统进行多目标、多参数优化,以使车体的垂向振动位移和加速度最小。分析比较优化后的结果可知,多目标优化结果明显优于单目标优化结果,悬挂参数的取值和优化目标有很大的关系,不同的优化目标会得到不同的优化结果。     

Steady state analysis of towed marine cables

Efficient numerical schemes were presented for the steady state solutions of towed marine cables. For most of towed systems, the steady state problem can be resolved into two-point boundary-value problem, or initial value problem in some special cases where the initial values are available directly. A new technique was proposed and attempted to solve the two-point boundary-value problem rather than the conventional shooting method due to its algorithm complexity and low efficiency. First, the boundary conditions are transformed into a set of nonlinear governing equations about the initial values, then bisection method is employed to solve these nonlinear equations with the aid of 4th order Runge-Kutta method. In common sense, non-uniform (sheared) current is assumed, which varies in magnitude and direction with depth. The schemes are validated through the DE Zoysa's example, then several numerical examples are also presented to illustrate the numerical schemes.     

海洋拖曳系统对船舶操纵性能的影响

将拖曳母船、拖缆和拖曳体视为一个相互作用的整体,利用耦合边界条件,将拖缆顶端和底端的张力与其产生的力矩,分别计入船舶操纵性运动方程和拖曳体六自由度运动方程,结合拖缆的有限差分方程,建立了船/缆/体耦合运动模型,采用数值计算方法,对比分析了海洋拖曳系统对船舶操纵性产生的影响.计算结果表明:当计入拖缆和拖曳体耦合影响后,船舶稳态运动时的速度会降低,改变量为3％～5％;船舶回转机动时,速度、回转半径与横摇角会降低,改变量分别为2％～3％、2％～4％和11％～21％.采用船/缆/体耦合运动模型计算得到的船舶操纵性能符合实际,可为预报海洋拖曳系统的运动信息提供理论依据.     

Dynamic response analysis of towed cable during deployment/retrieval

A numerical approach was developed to analyze the transient behavior of towed cable during ac- tively controlled deployment/retrieval (DR). The cable motion is described by the lumped parameter method, its corresponding boundary conditions are presented. In view of its varying length during DR, two auxiliary arguments are introduced to describe its continuous varying length and discrete number of nodes(equations), the length is determined by the pay out(or reel-in) rate, which is then used to determine the node number by a logic relation. For the discrete mathematical model of towed cable, an algorithm was developed to deal with the discrete governing equations. The simulation results indicate that the cable experiences more com- plex motions due to its varying length, and tension fluctuates seriously in the startup and ending stage of deployment/retrieval. The effect of towing ship's motion in waves on cable during deployment/retrieval is also considered via numerical simulation.     

采用电磁制动器的拖挂式房车制动力分析研究

从法规对拖挂式车辆制动力的要求出发,首次建立了采用电磁制动器的拖挂式房车制动力模型,通过改变电磁制动器电磁体通电电流,来实现对房车制动力大小的调节.得出了电磁制动器电磁体通电电流的合理控制范围,并对分析结果进行了试验验证.试验结果表明,制动器制动力模型正确、理论分析合理.为进一步研究主、房车制动力大小匹配,提高拖挂式车辆的制动稳定性,提供了重要依据.     

采用电磁制动器的拖挂式房车制动力分析研究

从法规对拖挂式车辆制动力的要求出发,首次建立了采用电磁制动器的拖挂式房车制动力模型,通过改变电磁制动器电磁体通电电流,来实现对房车制动力大小的调节.得出了电磁制动器电磁体通电电流的合理控制范围,并对分析结果进行了试验验证.试验结果表明,制动器制动力模型正确、理论分析合理.为进一步研究主、房车制动力大小匹配,提高拖挂式车辆的制动稳定性,提供了重要依据.     

Parametric vibration and vibration reduction of cables in cable-stayed space latticed structure

Mechanical model and vibration equation of a cable in cable-stayed sparse latticed structure (CSLS) under external axial excitation were founded. Determination of the mass lumps and natural frequencies supplied by the space latticed structure (SLS) was analyzed. Multiple scales method (MSM) was introduced to analyze the characteristics of cable's parametric vibration, and the precise time-integration method (PTIM) was used to solve vibration equation. The vibration behavior of a cable is closely relative to the frequency ratio of the cable and SLS. The cable's parametric vibration caused by the external axial excitation easily occurs if the frequency ratio of the cable and SLS is in a certain range, and the cable's vibration amplitude varies greatly even if the initial disturbance supplied by SLS changes a little. Furthermore, the mechanical model and vibration equation of the composite cable system consisting of main cables and assistant cables were studied. The parametric analysis such as the pre-tension level and arrangement of the assistant cables was carried out. Due to the assistant cables, the single-cable vibration mode can be transferred to the global vibration mode, and the stiffness and damping of the cable system are enhanced. The natural frequencies of the composite cable system with the curve line arrangement of assistant cables are higher than those with the straight-line arrangement and the former is more effective than the latter on the cable's vibration suppression.     

弹性支承块式无砟轨道冲击振动传递衰减特性试验

针对重载铁路弹性支承块式无砟轨道(LVT)在实际应用中出现的弹性部件变形过大、易损坏等问题, 优化设计了既有弹性支承块, 将支承块短侧边坡度由1∶17.00调整为1∶4.85, 取消了块下垫板, 并采用一体化弹性套靴; 为验证设计成果, 建立了传统型LVT和改进型LVT足尺模型, 采用质量为1 120 kg的重载货车轮对, 以20 mm的落高进行落轴冲击试验, 分别从时域和频域角度对比分析了冲击作用下竖向振动在钢轨、支承块、道床板、底座板及地面等结构部件沿线路纵、竖、横向的传递衰减特性。研究结果表明: 轮轨产生的高频振动能量沿钢轨纵向传递, 低频振动能量传递给下部其他轨道结构; 竖向冲击振动在纵、竖向传递的过程中不断衰减且衰减速率逐渐降低, 在支承块和道床板表面横向传递过程中, 向外侧边缘传递振动增大; 相比传统型LVT, 改进型LVT整体弹性系数减小21.1%, 而阻尼系数增大5.4%, 其振动周期、衰减时长、振动峰值分别比传统型LVT小37.0%、21.3%和3.4%, 各结构部位功率谱密度峰值比传统型LVT小30%以上; 改进型LVT轨道结构各部位Z振级比传统型LVT小, 在地面处减小了3.65 dB, 能更有效、迅速地衰减轮轨冲击力和轨道结构振动, 振动水平更低, 降低了冲击作用对环境的影响。研究结果对于开展LVT减振性能试验验证、优化与工程应用有参考价值。     

基于振动能量的内燃动车组柴油机组振动烈度分析

车载设备的振动水平不仅影响设备安全可靠运转,也影响周围环境的振动噪声．降低车辆的乘坐舒适度．为研究设备振动水平,本文建立了单自由度系统振动模型,分析了单自由度振动系统的振动能量特征．借鉴基于振动速度的振动烈度评价方法,推导了基于振动能量的等效振动速度的振动烈度公式,并采用基于振动速度和基于振动能量的两种方法,分别评价了某型内燃动车组（DMU）动力包的柴油机组振动烈度．结果表明：机组的振动烈度均随运转速度呈递增趋势,基于振动能量的振动烈度评价方法更能全面反映机组的振动水平和动态特性,为评估车载设备振动水平提供了新的评价方法．     

Robust Spectral Estimation of Track Irregularity

Because the existing spectral estimation methods for railway track irregularity analysis are very sensitive to outliers, a robust spectral estimation method is presented to process track irregularity signals. The proposed robust method is verified using 100 groups of clean/contaminated data reflecting he vertical profile irregularity taken from Bejing-Guangzhou railway with a sampling frequency of 33 data every 10 m, and compared with the Auto Regressive (AR) model. The experimental results show that the proposed robust estimation is resistible to noise and insensitive to outliers, and is superior to the AR model in terms of efficiency,, stability and reliability.     

能量回馈式主动悬挂的鲁棒控制器设计

为了改善具有参数不确定的能量回馈式主动悬挂系统的稳定性、减振性能以及能量回馈性能,对含摄动的系统模型进行了鲁棒控制器设计,并给出了系统的能量平衡条件.在MATLAB/SIMULINK下,对控制系统进行了仿真.结果表明,鲁棒控制器使得能量回馈式主动悬挂系统稳定;相比传统最优控制器,减振性能得到明显改善;控制作用力、悬挂动...     

汽车鼓式制动器的可靠性稳健优化设计

在汽车鼓式制动器设计中考虑不确定因素的影响,将可靠性优化理论、可靠性灵敏度分析与稳健设计方法相结合,以制动效能因数为目标函数建立制动器可靠性稳健优化数学模型。把制动力矩、摩擦衬片压力的可靠性灵敏度溶入可靠性优化设计模型之中,将可靠性稳健优化设计转化为满足可靠性要求的多目标优化问题。实例计算表明,稳健优化后的制动器不仅有较高的制动效能和可靠性,还具有较低的可靠性灵敏度,取得了满意的结果。     

鲁棒性PID控制器的自整定研究

在深入分析现有参数整定方法的缺点的基础上,提出了时域参数k,T,子与频域参数Kc,Tc之间的转换关系,并用数值方法拟合成简单的计算公式,由此提出了一种既可开环测试也可闭环测试模型参数的鲁棒性PID自整定算法。仿真表明,该自整定算法具有较快的响应速度、较小的超调量和较短的调节时间,是一种通用的、实用的算法。     

Robust Optimization Design of Metro Handrails

This paper presents the robust design and response surface method(RSM) based on finite element analysis for the optimization design of metro handrails. The response surface can be created for each output parameter. Sequential quadratic programming is used for the optimization of metro handrails. Taguchi design is employed to investigate the sensitive controlling factors for the strength and mass of metro handrails, by taking the material density, the column and cross bar thickness as controlling factors, and the acceleration, the elastic modulus and the fluctuation of material density as uncontrollable factors. Then, the best combination of controlling factors is found. The results by different methods show that the method of Taguchi design can improve the robustness of the structural performance and reduce the mass.     

桥梁抗震分析方法

介绍了现行桥梁抗震计算分析的几个方法.确定性方法中的弹性静力法,静力弹塑性分析,反应谱法,时程分析法;概率性抗震分析方法中的随机振动虚拟激励法.并对各个方法的优缺点加以说明,着重介绍了随机振动虚拟激励的基本原理和特点.最后提出了有待进一步研究的几个问题.     

桥梁抗震分析方法

介绍了现行桥梁抗震计算分析的几个方法．确定性方法中的弹性静力法，静力弹塑性分析，反应谱法，时程分析法；概率性抗震分析方法中的随机振动虚拟激励法．并对各个方法的优缺点加以说明，着重介绍了随机振动虚拟激励的基本原理和特点．最后提出了有待进一步研究的几个问题．     

曲轴扭转-纵向耦合振动分析

分析了曲轴的扭转—纵向耦合振动机理,建立了基于集总参数模型的曲轴扭—纵耦合振动数学模型．应用该模型对曲轴扭—纵耦合振动进行了数值仿真．结果表明：耦合作用会使振动加剧,但其倍频扭振响应可以忽略,而且通过改变扭振固有频率和纵振固有频率可对耦合作用进行调整。