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[结构振动] 急问!!什么是数值阻尼

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发表于 2010-12-4 21:38 | 显示全部楼层 |阅读模式

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(numerical damping)我翻译成数值阻尼  这是个什么东西啊?   以前没听说过   说的加0.5%的数值阻尼  怎么在动力学方程中加啊??  谢谢啦@@    很着急@@
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发表于 2010-12-7 12:50 | 显示全部楼层
请问楼主是在什么文献里看到的这个词?
ANSYS的帮助里有一段,我贴在这力你看看吧。

3.4. Damping
You can specify two types of damping in ANSYS:
Numerical Damping
Structural Damping
3.4.1. Numerical Damping
Numerical damping is associated with the time-stepping schemes used for integrating second-order systems of equations over time. ANSYS provides the Newmark method and the HHT method for transient dynamic analysis of structural systems. Numerical damping for these schemes is determined by the parameter values specified via the TINTP command.
Numerical damping stabilizes the numerical integration scheme by damping out the unwanted high frequency modes. For the Newmark method, numerical damping also affects the lower modes and reduces the accuracy of integration scheme from second order to first order. For the HHT method, numerical damping affects only the higher modes and always maintains second-order accuracy.
ANSYS uses a default value (TINTP,GAMMA) of 0.005. The value that you select should be based on the problem at hand. A sensible value to try initially is 0.1. Use the lowest possible value that damps out nonphysical response without significantly affecting the final solution. Problems involving rigid body translational motion, other forms of damping, or dissipative mechanisms like plasticity or friction typically require smaller values for numerical damping. Larger numerical damping values are usually necessary for problems involving rigid body rotational motion, elastic collisions (dynamic contact/impact), and large deformations with frequent changes in substep size.
3.4.2. Structural Damping
Structural damping refers to physical damping present in the system. You can specify the damping at the material level via viscous material models or dashpots (for example, COMBIN14 elements). At the structural level, you can specify it as modal damping or Rayleigh damping. For more information, see Damping in the Structural Analysis Guide.

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发表于 2010-12-7 14:36 | 显示全部楼层
 楼主| 发表于 2010-12-10 13:02 | 显示全部楼层
O(∩_∩)O谢谢楼上两位的帮助@@
发表于 2010-12-10 16:21 | 显示全部楼层
数值阻尼应该是数值分析自身引入到系统中的附加阻尼,不同的数值分析方法有不同的数值阻尼,同意算法,采用不同的控制参数,其数值阻尼阻尼也会不同,当然有的数值算法是不会产生数值阻尼的。
数值阻尼可以从两个方面来看待
一方面数值阻尼可以提高计算过程中的收敛性,但是另一方面数值阻尼又会导致系统出现一定的滞后现象
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