how to request force-displacement curve(ls-dyna solver)

Altair Forum User

Hi,

 

 

Recently I have done a crashing simulation, but I can get force-time curve from key word RCFORCE and the displacement information from key word NODEOUT. But I just cannot combine them into force-displacement curve.

 

Is there any way that I can do it?

 

Many thanks.

Altair Forum User

Hi,

 

1. create a displacement / time curve
2. create a force / time curve
3. create a new empty curve ('Add' in define curve panel)
4. switch to 'Math' type
5. select at the 'Curves...' selection dialog your displacment / time curve for x
6. select at the 'Curves...' selection dialog your force / time curve for y
7. change the x (e.g. p1w1c1.x) into y (p1w1c1.y) at the curve for x (displacement)
8. press Apply and switch off curve one and two...

 

Best regards,
Mario

Altair Forum User

Hi Mario,

 

Thank you for your reply. I just have another question.

 

I have successfully generate the force-displacement curve by following your instructions. Is it possible to apply a SAE 10Hz filter to the force-displacement curve I just generated since I can see there is a lot of noise within the curve.

 

 

Many thanks.

Altair Forum User

forgot something in the precious post. There is only options like 60Hz, 120Hz in the menu. And if I can apply a 10Hz filter, how should I do it?

Altair Forum User

I just got another issue. when I tried to apply the SAE60 filter to the force-displacement and force-time curves, I got two same warning message: referenced page is not valid. I didn't change the file location and haven't made any modification to the files. I can't figure out the meaning of this message???

 

 

Many thanks.

Altair Forum User

Hi,

 

you can apply a low-pass filter of course only in a time domain (be sure, that you are using seconds).

Filter your force / time curve and use the new one for the creation of the force / displacement. You have to do the filtering before the creation of the new curve!!!

 

Install the MVP_Toolbar, a freeware tool from Altair. You can download it at ftp://ftp.altair.de/pub/hyperworks/support/macro_toolbars/ .

Here you have a very good menu and dialogs to adjust the filter class and so on. 

 

Your last issue i can't understand, check the parameters of your curves e.g. p1w1c1 means page 1, window 1, curve 1

 

Best Regards,

Mario

Altair Forum User

Hi Mario,

 

If I don't use the MVP tool for filter (actually it looks like bit hard for me to get started), how should I apply a 10Hz filter to the curve?

 

I saw there is one option called SAE General which I think is a self defined tool to apply any filter class. For the 10Hz class, what should I put in the three displayed fields: curve(time=second), filter class, time conv. ?

 

Many thanks.

Altair Forum User

Hi,

 

Curve: your force/time curve (double click on 'curve')

Filter class: 10 (for 10 Hz)

time scale to s: 1 (if you have seconds) (you can still have a curve in ms, scale it here to second, since filters always need seconds)

 

In any case, try to install MVP_Toolbar and the life is a lot easier...

 

Regards,

Mario

Altair Forum User

Hi Mario,

 

After adding the line '{mvp_toolbar_dir = '<adapt path>/MVP_Toolbar';include(mvp_toolbar_dir + '/preferences_macro.mvw')}' at the end of the preference file, i got a error message 'could not preprocess the file' as soon as I open the hypergraph. 

 

Also in the installation guide saying 'Load via the menu 'Set Preference File ...'', but there is no option 'set preference file' in the menu.

 

Please help.

Altair Forum User

Hi Thomas,

 

add the following lines at the end of your preferences.mvw (located in directory HW):

 

{mvp_toolbar_dir = 'C:/Altairwin64/MVP_Toolbar'}
{include(mvp_toolbar_dir + '/preferences_macro.mvw')}

 

C:/Altairwin64/MVP_Toolbar has to replace by your local location.

 

You can include the file of course in one line: {include('C:/Altairwin64/MVP_Toolbar/preferences_macro.mvw')}

Be sure that the directory points to your location.

For me it works in this way.

 

You can load preference files in Hyperview at 'Files->Load->Preference File'. First step is to register the file (press register and search your file). Second step ist to load it.

 

Best regards,

Mario

Altair Forum User

Hi Mario,

 

Thanks for your tips.

 

Now I can see *filter, *misc etc. menu as soon as I open the HV without registering. Is this normal?

 

I have a look at filter menu, it looks like there is no predefined 10Hz filter. What should I do to pick up the 10Hz filter?

 

 

Many thanks.

Altair Forum User

Hi Thomas,

 

all the menus from MVP_Toolbar have a star, thats OK.

10 Hz isn't a standard filter, so you have to go the manual way...

 

Regards,

Mario

Altair Forum User

Hi Mario,

 

If I go to the manual way, how can I apply 10H filter?

 

Thanks.

Altair Forum User

Hi,

 

it is answered some posts before... use the SAE General filter:

 

Curve: your force/time curve (double click on 'curve')
Filter class: 10 (for 10 Hz)
time scale to s: 1 (if you have seconds) (you can still have a curve in ms, scale it here to second, since filters always need seconds)

 

Regards,

Mario

Altair Forum User

good day mario

 

in define curve for load body.. how can i define the load_body curve as a horizontal line (ordinate value equal to the gravitational acceleration)

 

what value need I put in ordinate.? and also what value need I put in abscissa.?

 

hope you can help.. thanks.