Internal Energy Higher Than K.E

Altair Forum User

Dear Sir,

 Thanks for the help, i have run the analysis with n=5 and ishell 24 formulation in radioss but the problem couldn't be resolved

1)still the internal energy is high from the start of the run .

2) after 14 iterations its saying time step error is equal to zero, though the mass error is 1.3e-1 at that time and energy error is -8.1 which are acceptable limits.

Attached are the pics and out files and please help me with this.

Thank You.

 

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Altair Forum User

Hi Ramakiran,

I have corrected the model and it runs fine. The model has been sent to you via mail.

Changes made in the model:

As you can see there is high hourglass energy in your model. In order to fix this create an output block for all the parts and in HyperGraph plot hourglass energy for each component and thereby we can understand which component is responsible for this higher hourglass energy. In this model it was a solid component and I made the Isolid formulation to 24.

 

Another issue was the high energy error in the model. This is caused by having the master node of an RBODY attached to an element.  RADIOSS by default moves the master node of the RBODY to the center of gravity of the RBODY.  If the master node is attached to an element then this causes element deformation and adds non-physical energy to the simulation which causes the energy error. The solution is to run HyperCrash model checker and accept the automatic fix which will create a new master node not attached to an element and make the old master node a slave.  Or the model checker in HyperMesh can find all the rbodys with this issue but cannot auto fix like HyperCrash.  Instead once you isolate all the RBODY in HyperMesh you can card edit all of these /RBODY at once then then pick config=rigidlink, type=RBODY and set Icog=3 which will tell RADIOSS not to move the master node.

 

Some changes were made in the interface defined.

 

 

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