查询词典 critical damping

Many researchers have devoted their work to the development of modal analysis extraction techniques in order to obtain more reliable identification of the modal parameters. There are many damping identification methods, but each one has different merit and defect. In order to find which one is the most reliable method with respect to certain characteristics, this thesis focus on how to identify structure's damping in time domain. The following works have been done in this thesis: 1. Investigate four modal analysis methods——the LSCE Method, the Ibrahim Time Domain Method, the Time Domain Collectivity Modal Parameter Method, the Rational Fraction Polynomial Method and improve on the ITD Method in arithmetic.

本文主要做了如下工作： 1、集中研究了四种常用的模态识别方法，即最小二乘复指数法、Ibrahim时域法、时域总体模态参数辨识法及有理分式多项式法，并对ITD法在算法上进行了一定的改进； 2、建立结构动力模型，利用这四种方法在具体条件下识别结构的阻尼，并绘制相应的图； 3、讨论不同的情况下，不同的识别方法对阻尼识别精确性的影响； 4、基于业已明确的阻尼识别的精确性，根据研究的需要，指出在实际的识别过程中，如何选择最佳的识别方法以及识别过程中需要注意的问题； 5、选择最为精确的阻尼识别方法，以导师李书进教授在日本京都大学防灾研究所强震反应实验室所做的一足尺木制结构房屋的动力测试实验为实测模型，识别其阻尼； 6、在本文的最后，尽作者所知，提出了一些需要改进的地方，并对未来的研究方向给出了作者的建议。

ABSTRACT:The half-power bandwidth method is the commonly used method at home and abroad, the authors discover that factors, such as the sampling frequency, the frequency resolution, the ratio of the sampling frequency to the signal frequency, the analyzed width and the damping ratio, make the estimated damping ratio fluctuate vastly. Mostly the result is incredible except for some conditions, the error is sometime amazing, which is not acceptable.

半功率带宽法是国内外常用的测试阻尼的方法，笔者发现半功率带宽法由于受到信号处理中的①采样频率SF②频率分辨率△f③采样频率与信号频率之比K ④采样分析的长度T和⑤阻尼比D的大小等因素的影响使得测得的阻尼比值波动很大，除少数状态是可信的外，多数状态是不稳定的，有时误差惊人，得到的测试数据不能使用，易导致错误的结论。

The effect of pre-deformation on the damping capacity was studied and the effect of the movement of Shockley partial dislocation on the damping capacity of FeMnCr alloy was analyzed by dislocation theory.

研究了不同的预变形量对FeMnCr合金阻尼性能的影响，并根据位错运动理论，分析了 Shockley不全位错的运动对该合金阻尼性能的影响。

Considered the factor of damping,a single degree of freedom s dynamic model of the high-speed cam mechanism is established.Choosing the law of sine acceleration motion as the excitation function,a displacement and acceleration dynamic response equations of the main vibration phase and residual vibration phase,the working dynamic response change curve through the inferential reasoning working end movement equation is derived.The result is obtained that different period and damping ratio have different impact

建立了考虑阻尼因素的等效单自由度高速凸轮机构的动力学模型，以正弦加速度运动规律方程为激振函数，推导出了从动件系统主振段和余振段的位移和加速度动态响应方程并绘制出了动态响应变化曲线，得出了不同阻尼比和周期比对主振段和余振段的动态响应，从而为高速凸轮机构的合理设计提供了一定的理论依据。

The article put forward "the equivalent linearization methed for the nonlinear damping in the stationary random process" in order to solve the problems of nonlinear damping, which is widely adopted in automobiles.

为了解决汽车上广泛采用的非线性阻尼问题，文中提出"平稳随机过程中，非线性阻尼的等效线性化方法"，并给出一般形式的解答。

The effects of trace Ce and La on the damping capacity of aged Zn-22%Al have been studied using TEM,SEM and room temperature low frequence torsional pendulum damping meter.

采用自然时效、人工时效等热处理工艺，借助透射电镜和室温低频扭摆内耗仪，研究了微量Ce，La对高阻尼Zn-22%Al合金时效后显微组织和阻尼性能的影响。

The influence of structural damping coefficients on the peak value of the response of the vibration generator was investigated to determine the damping parameter according to the calculations of frequency response on the vibration generator.

通过对仿真模型进行频率响应计算，研究了阻尼对振动台响应峰值的影响情况，确定了各阻尼系数的取值。

The behavior and performance of the MR valve with both annular and radial damping gaps is expressed in terms of non-dimensional parameters and the efficiency of the MR hydraulic actuator system with the MR valves with both annular and radial damping gaps in Wheatstone bridge network is studied

同时推导了基于平板模型的同时具有圆环和圆盘阻尼间隙的磁流变阀的非量纲的体积流量，得到了桥式连接的磁流变阀工作时驱动泵效率的计算模型。

It introduces a kind of novel loading test system, based on the operation principle of damper. this loading system is operated by the driving motor. it realizes the loading, in that the damper has a negative drive force that puts on the motor. Based on the ordinary electromagnetic damper, the thesis presents a novel hybrid excitation electromagnetic damper which has adjustable work characteristic, analyses the working principle and structural feature of the electromagnetic damper, deduces the formulas to calculate the eddy current density through the Electromagnetic theory, analyses the distribution of the eddy current in the cotyloid rotor, and also studies the method of calculating the damp torque, establishes the mathematical model of the electromagnetic damper, analyses the relationship between the electromagnetic damper structural parameter and damp torque, researches the engineering design and analysis method of the electromagnetic damper, provides theory foundation for the design and analysis of the electromagnetic damper, contrives a hybrid excitation electromagnetic damper that satisfies the target request, designs a set of compound excitation electromagnetic damping loading control system whose control core is AT89C51 monolithic integrated circuit, analyses the electric circuit part, and carries on the experimental test to this set of electric circuits. Finally it debugs this electromagnetic damping loading system, this system satisfies the target request proposed.

论文提出了一个全新的加载测试系统种类，该加载系统是在阻尼器工作原理基础上，利用电动机拖动阻尼器运转，从而阻尼器产生一个与运动方向相反的阻尼力矩，该力矩作用在电动机上实现对电动机加载测试；同时，论文在一般电磁阻尼器基础上提出了一种新型的可调式复合励磁电磁阻尼器结构，该种阻尼器的工作特性在一定范围内可进行调节；论文分析了电磁阻尼器的工作原理和结构特点，运用电磁场理论分析推导了电磁阻尼器的涡电流密度公式，分析了涡电流在转子杯内的分布图，并对阻尼力矩计算方法进行了研究，建立了电磁阻尼器的数学模型，分析了电磁阻尼器结构参数和阻尼力矩之间的关系，对电磁阻尼器的设计和分析方法进行了研究，为电磁阻尼器的工程设计建立了理论基础；设计了满足技术指标要求的复合励磁电磁阻尼器和一套以AT89C51单片机为控制核心的复合励磁电磁阻尼加载控制系统，对该控制系统硬件电路各部分进行了分析和设计，对软件进行了设计，并对控制电路进行了试验调试，该系统满足所提出的加载指标要求。

This is due to the dry friction damping is merely limited to shroud interface and is a standard local nonlinear problem, when directly solving it, most operations will be used meaninglessly to regenerate its linear elements except for modifications of some elements of stiffiness matrix and damping matrix.

这是由于干摩擦阻尼只局限于凸肩接触面，是典型的局部非线性问题。直接迭代求解时，除了只需对系统刚度矩阵、阻尼矩阵的个别元素进行修正外，有相当一部分运算毫无意义地用于线性元素的重新生成上。

Now she was hungry and angry.She began to smoulder.

现在她又饿又气，她开始流露难以抑制的怒火。

You have placed our iniquities before You, Our secret sins in the light of Your presence.

诗90：8 你将我们的罪孽摆在你面前、将我们的隐恶摆在你面光之中。