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Altair Forum User

Hello together,

 

At the moment I am working on impact simulations in Radioss. I have an aluminium cylinder (solid elements, MAT Law 2, Initial Velocity) impacting a rigid wall. The total energy (TE = KE + IE) should be constant, but there is a jump in the curve. The DTE curve remains constant. The external work shows a decrease, too. Is my simulation correct? Should i use the DTE curve instead of the TE curve for validation? 

 

 

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tinh

Hi,

how's about hourglass?

where are KE & IE curves?

Altair Forum User

Hi,

 

Can you plot IE and Hour glass energy? 

 

Taking into account the external works, the total energy must remain constant or decrease slightly. The total energy can increase at the end of the computation, during the spring back or at the beginning during the first cycles.

Internal energy + Kinematic energy + Hourglass energy + Contact Energy + … = Variation of the External Work

If under-integrated elements are used, the total hourglass energy must remain lower than 10% of the total energy. If this is not the case, the mesh should be reworked or elements with physical stabilization method should be used.

Altair Forum User

Hi,

 

the HE is constant 0, due to the usage of solid element formulation 14 (full integrated).

 

The HE; IE and KE curves are attached. 

The model is really simple. It is a cylinder (with solid elements) impacting a rigid wall.

 

 

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Altair Forum User

The slight decrease could be due to contact with the rigid wall. 

 

External work should be zero and near to zero as the energy is transformed from one form to the other. This is perfectly valid for static and quasi-static cases. 

 

 

Altair Forum User

So the simulation results are correct?

 

I made another simulation yesterday. This was a simulation of a sphere impacting a rigid wall. The sphere had the same property, material and initial velocity as the aluminium cylinder above. There was no slight decrease in the total energy. Due to this i am not shure about the above decrease

tinh

Is there any friction factor in contact?

the cylinder has sharp edge, so contact force is different from case of sphere

Altair Forum User

There is no friction factor defined...

Altair Forum User

Hi,

 

Can you share the engine .out for both the analyses? 

Altair Forum User

Hi,

 

the files (.rad, .out .h3d, t01 and so on) are attached.

Thank you