# JuanMiguel

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1. ## Volume in Monitored volumes

Hello George, Thank you for your answer. I do not understand yet why volume is calculated using the thermodynamic equation. So, how is calculated the initial volume if we only know the initial pressure and temperature but we do not know the initial mass inside the control volume? I though that it was calculated using a geometric approach, using the position of nodes and elements, and then using some algorithm to calculate the enclosing volume. Then this volume would be used to calculate other thermodynamic variables such as pressure or temperature, and not the reverse. That is why I supposed having common surfaces outside the volumes will cause an error in the volume calculation.
2. ## Volume in Monitored volumes

Post modified: Quoting George message
3. ## Volume in Monitored volumes

Hello, I wanted to know how Radioss calculates at every time step the volume of a monitored volume, i did not find the answer in the theory manual. I'm using four monitored volumes type COMMU1, comunicated by dummy surfaces, but the geometriy is a little bit complex and during the simulation, the common surfaces are sometimes outside the monitored volumes as you can see in the image, the green surface on the top. How this impact What would be the difference between using multiple monitored volumes COMMU1 and only one monitored volume type AIRBAG? Thank you
4. ## Time step smaller than DT/INT/DEL

Hello, I am doing a study inflating an airbag with a particular shape and there are a lot of contacts between surfaces, that I modeled with interface type 7. I have some troubles because there are some nodes that pass through master surfaces (even if the interface is activated) but then the contact is applied and the nodes can not pass through, creating high contact forces and reducing the time step. I wanted to use the control card DT/INT/DEL to delete the interface in those nodes, I fixed Tscale to 0.9 and Tmin to 1.0 e-4. When I run radioss, time step reduces up to 5e-5, some nodes are deleted but not those that passed through surfaces and have high contact forces. Any idea about how can I deactivate interfaces in nodes where the contact force is higher than a fixed value? Thank you
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