Decreasing time step on Incremental Forming

Altair Forum User

Hi, I am doing an incremental forming simulation, that I need to analyze the properties in the end of the analysis. However, my analysis is decreasing in time step or when i try to fix it, the model mass increase. Another problem is my model vibrates and I could not damped it with / DYREL. My error is very high, in the beginning it's around 100% and decrease to 50% in the end.

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Altair Forum User

Hi,

Negative Energy Error represents energy dissipated from the system and this can be from many sources. If the initial energy in the system is low, then it is possible to have large Energy Errors early in a simulation that reduce as energy is added to the system. This is because, small numerical differences in the energy causes large percentage Energy Errors. And in your case since it decreases towards the end it seems fine.

For the time step is reducing during the run :check which object is responsible for the low  time step (.out file). It can be an element, a node or an interface.

>>For an element, check the related material.There must not be an error in the units system that this data is given in. check the element size also

>>For a node, check the characteristics of connected elements. If the node is on the master side or the slave side of an interface, this interface must be verified.

>>For an interface, the gap of the interface must be verified if some failure happens on the master or the slave side of the interface.

In your model the contact energy seems to be very high. Set recommended parameter for the contact definition.

   Suggested parameters for Type 7 contact are 

          Istf=4

          Igap=2

          Fscale_Gap=0.8

          INACTI=6

          Gap_min=

          Fric = 0.1

          Iform=2

You can also remove the friction value from interface and check whether it is contributing the high energy error. If so, then you can ignore the high contact energy.

For /DYREL, please try with Relaxation factor of 1 and T=0.18