How can I remove numerical damping completely with the generalized alpha method?

Rolando Ho
Rolando Ho New Altair Community Member
edited October 2023 in Community Q&A

Hi,

Is there a way to circumvent the limit of TC1 >  -0.333 in the TSTEP control card?

I’m currently running a non linear transient analysis where I wish to see the effects of material damping on my model, Consequently, any numerical damping is not desired. I am using a multiscale material model from multiscale designer, hence I can’t use any explicit time integration methods and am therefore limited to the generalized alpha method.

From the attached paper, it suggests that the parameter rho_infinity is able to control how much numerical damping is present in the generalized alpha method.

image

I wish to therefore use a rho_infinity setting of 1 as no numerical damping will be present throughout the whole frequency spectrum.

 

rho_infinity relates to the TC1 setting in optistruct the following way:

According to optistruct's documentation, TC1 corresponds to -1*alpha_f in the attached paper, which relates to rho_infinity through the following relationship:image

This suggests that a rho_infinity of 1 needs a TC1 setting of -0.5 which currently is not allowed by optistruct.

Is there currently a method to circumvent this limitation?

Thanks in advance for your help.

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