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Hi,
What is the best contact type generally?
if the answer is type7, what is the best properties of type7 contact?
There are different type of contacts available in RADIOSS and they are applied based on the applications. For example, Type 11 is defined for an edge to edge interface where Type 2 is used when user wants to kinematically connect a set of slave nodes to a master surface.
Interface type 7 is a multi-usage impact interface, modeling contact between a master surface and a group of slave nodes. Interface type 7 is a general purpose interface and can simulate all types of impact between a set of nodes and a master surface.
The suggested parameters for Type 7 contact are: Istf=4
Igap=2
Fscale_Gap=0.8
INACTI=6
Gap_min=0.1
Fric = 0.1
Iform=2
Please go through http://www.altairuniversity.com/learning-library/vii_d_sliding-interface-type-7-in-radioss/ which is a webinar on Type 7 interface.
Ifric is remained :0
but fric is 0.1
When i searched from internet , generally static friction between steel to steel is 0.8
Why is there differencies?
If you have the proper friction value you can always run with it. In many cases users may not have the value and so this value was provided, with which we can define the interface properly.
Hi, There are different type of contacts available in RADIOSS and they are applied based on the applications. For example, Type 11 is defined for an edge to edge interface where Type 2 is used when user wants to kinematically connect a set of slave nodes to a master surface. Interface type 7 is a multi-usage impact interface, modeling contact between a master surface and a group of slave nodes. Interface type 7 is a general purpose interface and can simulate all types of impact between a set of nodes and a master surface. The suggested parameters for Type 7 contact are: Istf=4 Igap=2 Fscale_Gap=0.8 INACTI=6 Gap_min=0.1 Fric = 0.1 Iform=2 Please go through http://www.altairuniversity.com/learning-library/vii_d_sliding-interface-type-7-in-radioss/ which is a webinar on Type 7 interface.
Related to this informations;
Can we make Gap_min = 0.1 in all contacts , although thicknesses of materials which get contact are more than 2mm.
If you have specific contact criteria you have to use the same. These are generalized parameters which I shared above.
Hi
What is the ideal properties for type 11 ?
You can try with the below parameters:
Istf=4
Gapmin value
Inacti=6
Idel=2
what is type 2 contact and how to apply it?
TYPE2 is a tied interface that kinematically connects a set of slave nodes to a master surface. No relative motion between the master and slave will be allowed.
Please go through https://www.youtube.com/watch?v=-HdECgBC_lM&list=PLQ7KUGFuVz4u5y3SvIEIU07427-gATaG6 which shows creating Type 2 interface.
I use these parameters and the computation time increase at least 10 times. Before I only use
Could you please explain me the reason?
Thank
Hi @pohan,
In the penalty based contact, the interaction between the bodies is handled with spring elements that model the stiffness of the contact. Deep penetrations increase spring stiffness which leads to timestep drop. Try increasing the Gapmin (set Inacti=6 and Fpenmax=0.8 to avoid initial penetrations) which will allow the contact to work sooner and prevent deep penetrations Or you could try making the interface stiffer, Istf=3 which uses the maximum stiffness of the slave and master.
If timestep is low from the beginning, make sure there are no initial penetrations or intersections:
-in Hypercrash: Quality>Check all Solver Contact Interfaces
-in Hypermesh: Tool>penetration check
The material parameters should be realistic as they can influence contact stiffnes (depending on Istf flag) and special treatment may be necessary if contact is between soft and hard part.
Hi @Ivan
Thank you very much. I tried to do as you recommended but I still have the same problems
In fact my contact is self contact!
Please check the attached document from Radioss help, section: 'What is the meaning of: WARNING ID 94 and WARNING ID 477'
If the issue persists please share the model.
Unable to find an attachment - read this blog
Thank you very much I solved my problems.
But I found that
Iform = 2 is recommended for Implicit and low speed Impact Explicit Analysis
So I think for contact type 7 we should set Iform = 1
thanks for the update.
Can you share what was the problem and the solution?
I usually set Iform=2, because this setting is recommended in combination with Advanced Mass Scaling.
My problems is when I set Igap = 1 2 or 3 I got initial penetration so I set it to 0
