How I create Damping in Advanced Nonlinear Transient Analysis? 2

[jacksonfem]

Hi everybody!

I perform an anvanced nonlinear transient analysis with contact elements. How I give damping to elements? For example I want to force a ball by gravity and throw it to the floor. Well, I can do it, but without damping. How I do it? Also how I can give different damping to the ball and to the floor?

The dialog Load-->Dynamic analysis, don' t work in SOL601.

Sorry for my english.

 

[BlasMolero]

Dear Jacksonfem,
You have the following types of dampings in FEMAP & NX Nastran Advanced Nonlinear analysis (SOL601:

1.- Damping from numerical integration: you can achieve it by modification of the Newmark time integration parameters (alfa=0.25 & delta=0.5). The previous default values lead to no numerical damping, and higher (stable) values introduces some numerical damping. These values are defined in the "NXSTRAT Iteration & Convergence parameters" window of the Analysis Set Manager for Advanced Nonlinear SOL601,129 analysis, not in the "Model > Load > Nonlinear Analysis", this menu is only for NLSTATIC (SOL106) analysis.

2.- RAYLEIGH DAMPING: these are alpha & beta damping constants, and they are ALPHA1 & ALPHA2 in the PARAM command. Parameter ALPHA1 dampens the low frequencies (and the rigid body modes), and parameter ALPHA2 dampens the high frecuencies.
The program computes the Rayleigh damping matrix from the
stiffness and mass matrices at the time of solution start. The Rayleigh damping matrix is not updated during the solution.

3.- LOW-SPEED DYNAMIC DAMPING: if activated, the solver includes mass and damping effects in the analysis. Again these values are defined in the "NXSTRAT Iteration & Convergence parameters" window of the Analysis Set Manager for Advanced Nonlinear Analysis.

4.- The use of Damper elements: concentrated dampers and springs with dampers.

5.- Physical damping: Energy dissipation material effects (plasticity) and friction.

Also, you have CONTACT DAMPING:
• Adds normal and tangential viscous dampers to all contact nodes.
• Set via CTDAMP parameter in NXSTRAT.
• Damping can act only in the first time step (CTDAMP=1) or remain constant through out the analysis (CTDAMP=2).
• If it remains constant, the energy associated with damping is output.
• Very useful for stabilizing static problems and removing high frequency oscillations in dynamic problems.

Please revise the NX NASTRAN Advanced Nonlinear SOL601 manuals, there you have plenty of information.

Best regards,
Blas.

~~~~~~~~~~~~~~~~~~~~~~
Blas Molero Hidalgo
Ingeniero Industrial
Director

IBERISA
48011 BILBAO (SPAIN)
WEB:

http://www.iberisa.com

 

[jacksonfem]

First of all, thank you very much for the very analytical instructions!!!
I have tha manual for SOL601 but I don 't understand some things.

1)I know for Newmark parameters, but I don 't know how to use them. For example I want a damping of ?=5%. What I must input to alpha $ delta?

2)From where I adjust the Rayleigh Damping parameters alpha $ beta? I mean where is the PARAM command??

3)What is symbolize the low-speed dyn factor? I mean for ?=5% what I must input?

4)OK

5)OK

Also, what if I input damping fot the Define Material Tab? When it works? I don 't see any difference?

Thank you again Blas for your time!!!