How to create time dependant materiel properties/ time dependant friction

Which parameters do you want to be changed over time?

Is there anything else as a reference except time?

Regards,
Manuel.

There is only time as a reference.
In an orthotropic material I need to change the Young's modulus, the shear modulus and the Pioson's ratio.
I just want to change the value of friction.

Matze,

What exactly are you trying to model here?

Is it creep? In RADIOSS LAW42 you can prescribe shear modulus as function of time G(t). The function should be represented as prony series. Coefficients shall be fitted according to creep or relaxation test

See Altair RADIOSS > Reference Guide > Starter Input > Starter Keywords > /MAT:
/MAT/LAW42 (OGDEN)

Matze,

Also , if you have strain rate data you can use this in RADIOSS materials,

Strain rate is the rate of change in strain (deformation) of a material with respect to time.

Hi,
I am creating a model of two plates of an orthotropic material who are connected with a screw. The decreasing preloadforce over time is the examined subject. The changing material properties of the orthotropic material over time are known.

Hi,

Can you please refer to LAW 25 and LAW 15, where you can input orthotropic material properties.

LAW 25 is compatible with solid and shell elements whereas LAW 15 is compatible with only shell elements.

Please let us know if they are suitable for your analysis.

I am aware of these LAWs, my problem is that they are at best dependant to heat, though I need to somehow create/find an orthotropic material which is dependant to time. More precise for an solid object and with a change over time for the values of he Young's modulus, the shear modulus and the Pioson's ratio.

Matze,

currently I see only Isotropic options for time dependance,

Your model looks like a relaxation of material when stresses are redistributed and reduced when the system has reached a balanced static case, is that an accurate summation?

Jes, that is bassicly correct. I am interested in the decreasing preload force of the screw.

Are you saying it is not possible in Radioss or in Hyperworks? So is it possible with another solver?

Matze,

This should be possible, in fact I see that we may be able simulate this as a non linear quasi static with elastoplastic materials,

Please send me the material data you have so that I can better understand the physical problem we are trying to solve here,

Basicly I want to rebuild the Model in the picture below.
It simulates, as said, the loss of preload force of the screw due to the deformation of the orthotropic laminate in between.

Matze,

Since this is carbon epoxide and we can use LAW25 and /VISC/PRONY to simulate time dependence.

Of course you should understand that Radioss is an explicit code and we can not do simulation for 30h end time.

You will have to scale the time to some smaller value and simulate it quasistatically.

I thought /VISC/PRONY is only available for the material LAW66?

Matze,

It will work with Law 25 as well.

Ok, my problem then is, how to integrate /VISC/PRONY.
With Mat Law 66 there is a box, with Law 25 there is no box.

LAW 66:

Matze,

In that case is it possible to enter this card, find what it looks like in a deck with law 66 and enter this directly through the input deck.

Could you please explain this more explicid, this is Greek to me.

Matze,

you will have to add the /VISC_PRONY card manually in the 0000.rad file,

Open this file in a text editor and enter the parameters and save the file before running,

As a reference of how the card should look like, Look at the card syntax in help and perhaps you can also export the card with a law 66, look at this in a text editor and replicate this for a law 25 by manually editing the starter file (0000.rad) in a text editor.

Thanks I will try it.

Hai,

 Is it possible to simulate creep analysis with hyperworks?

If so, how can we give input values?

I have a component which is exposed to a constant temperature and load.

in this case how can I find out the life time?  

Hi Jodha,

Creep analysis is not available in OptiStruct for now.

We will let you know when it is available. 

So what about radioss?

If any possibility please let me know and also the other software which is particularly for creep analysis.

Hi,

Please replay me if anybody know anything regarding creep analysis??????????? /emoticons/default_sad.png' alt=':(' srcset='/emoticons/sad@2x.png 2x' width='20' height='20'> ....

Hi Jodha,

No, Creep material is not available in RADIOSS. RADIOSS is more focused on Explicit analysis where as creep is a slow process.

Maybe in coming releases, this might get added to RADIOSS/OptiStruct

Thanks Prakash....

thanks for your rply