Run time and load application time

Altair Forum User

Hi, 

I have query regarding analysis run time and load application time(loading condition).

Is it necessary that analysis run time and load application time should be same?

Herewith sending the a .jpg file for reference whereas run time is 500 millisecond and load application time in curve is 60000 millisecond.

Kindly suggest the solution.

Thank you.<?xml version="1.0" encoding="UTF-8"?>

Rahul Rajan_21763

Refer below link from our Radioss Ebook on Radioss file structure where we talk about Run time termination for impact & quasi static analysis.Its a 13 minute video after 5th minute you would find important parameter for Analysis.

https://altair-2.wistia.com/medias/9v47veeusj

Altair Forum User

Thanks very much Rahul R.

Now I have cleared about run time.

Will you tell me that what exactly energy balance in impact analysis?

Is there any video for energy balance??

 

 

Rahul Rajan_21763

Refer below post.

 

Altair Forum User

Hi Tushar,

The energy balance graph is plotted from the T01 file.
The physics of impact involves conservation of energy and momentum. When a moving object strikes a structure the force which decelerates the mass satisfies conservation of momentum.

 

If the energy is initially set in the model:

• Translational Total Energy (TTE) should be constant or slightly decreasing (loss of energy)

• TTE = IE + KE + RKE + CE + HE

• If energy absorption is the goal then most of the kinematic energy should be transformed to internal energy.

(IE- Internal Energy, KE- Kinetic Energy, RKE-Rotational KE, CE-Contact Energy, HE- Hourglass Energy)

 

The major points evaluated during post processing of an analysis can be viewed here: http://www.altairuniversity.com/wp-content/uploads/2012/08/WS8_Nov_2007.pdf

Please refer this case study also : http://altairatc.com/india/previous-events/2013/images/presentations/RNL-09_Frontal_Crash_SMLISUZU.pdf

 

 

Altair Forum User

Hi,

Is it necessary the energy curve should like figure1(attached)???

I run the some of analysis having different energy curve shown in figure.

Kindly clarify the same.

Thanking-You.

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Altair Forum User

Hi Thushar,

These are typical impact (fig 1) and quasi static simulation curves. Based on the loading conditions and nature of analysis, the energy graphs will vary.

 

Altair Forum User

Thanks very much for suggesting.

But how could I predict that my run is completed after observing the energy balance?

Rahul Rajan_21763

Whenever you have initial velocity as loading then its is the case of crash or Impact analysis.Then Figure 1 is the expected curve for such case.

 

I think in your case you have only gravity loading?

gopal_rathore

Hi,

Yes, it seems a drop test like scenario where after first hit, the object is bounding back and then again hitting and then again bouncing back.

Altair Forum User

Hi Tushar,

Observe your energy graph and from a point the system will be stable. That is, from that point the graphs will not have any fluctuations. In your Fig 1, it is clear that the system is stable from 0.025 seconds.  This is how you will conclude that you have ran the simulation for an ideal time.

As suggested by Rahul and Gopal your third plot is for a drop test case. These are some of the typical simulation curves we observe frequently.
 

Altair Forum User

Hi,

Thanks all of you for support.

Now, I am cleared about the energy balance.