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RADIOSS BLOCK120

Hello,

I am Myadam Nikhil. I recently started my dynamic simulations of few components by simulating a crash test where the component is made to hit the wall at a certain constant velocity. The component has been modeled using an orthotropic material, the properties of which are obtained from the experimental data. The component is made to impact the wall with a certain added mass. The input energy of the system (Kinetic energy) was found out to be 393.75 J (mass = 0.315 Kg and initial velocity = 50m/sec). But when the simulation is ran for a specific end time, the energy plots showed internal energy of the system greater than the input energy. Also the energy plot doesn't follow the usual characteristics.. The internal energy gradually increases to a maximum and then decreases back to its initial state. I faced this problem quite a few times and would request you to provide me with the best possible solution.

Please find the attached 'hm' file and snapshot of the energy plot

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

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Altair Forum User

Hi Nikhil,

I don't see anything unusual in the graph.

Altair Forum User

Hello Sir,

The general expected energy patterns mostly signifies that the material is absorbing energy while it is undergoing a collision, reaches a maximum which signifies the end of crushing of material and rebounds back from the wall during which the energy absorbed by the body remains in the form of plastic deformation of material. But from the patterns I received, the material is releasing energy once the collision ends and returns back to its original shape. From whatever I have learnt over the past few years by experimentally testing different materials, this is not the expected pattern because the any crushable material doesn't show this type of behavior.

Sir, I would kindly request you to have a look into it once again and let me know if the problem could be rectified.

This is just my opinion how I see the analysis and I might also be wrong. I will consider your views and work upon it

Altair Forum User

Nikhil,

Can you plot only for the crush-able material instead of global variables?

Altair Forum User

Sir,

Sorry that I couldn't reply at the earliest.

Please find the attached plots of both internal energy and total energy of the crushable material alone

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