damping in DTRAN

Hi,

from https://altairuniversity.com/free-ebook-learn-dynamic-analysis-with-altair-optistruct/

PARAM,G
• Structural damping (displacement proportional)
• Dimensionless, percent of stiffness
• Applied to the entire structure
• For example, to represent structural damping that is equal to 3% viscous damping at resonance, use 6% structural damping, i.e., 0.06.

 

In OptiStruct it is possible to enter this directly with the damping ratio using the following syntax: Param, G, 0.06 where 0.06 is equal to 2ζ. It is easy to find some damper values in terms of the damping ratio in the literature, this is the reason OptiStruct provides the user this possibility, but it is highly recommended that the user gets this value right for his models, and test it before use on virtual models, a wrong damper value can underestimate the dynamic responses. For some guidance on this we list typical values below:
The structural damping in general is typically 2%-10% depending on the type of construction:
Bolted steel ~6%
Reinforced concrete ~ 4%
Welded steel ~ 2%
These values should be used only for reference.

Thank you very much sir..

Suppose if i am giving any damping input value, it simulates the worst case scenario right?

So When i dot have the tested data with me i will go with no damping ?

Glad to help.

The damping effect is more pronounced at frequencies near the resonance peaks. The worst-case scenario is when the excitation frequency is near the resonant frequency and there is no damping.

When you are unsure about the damping, perform a sensitivity analysis by varying structural damping in the realistic range 2-10% and observe how much the responses of interest are affected.