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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.

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Guest

Hi,

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.

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On 29.06.2017 at 11:48 AM, George P Johnson said:

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.

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Guest

Hi,

If you have specific contact criteria you have to use the same. These are generalized parameters which I shared above.

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On 6/29/2017 at 10:48 AM, George P Johnson said:

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.

Hi

I use these parameters and the computation time increase at least 10 times. Before I only use

INACTI=6

Gap_min=0.1

Fric = 0.1

Iform=2

Could you please explain me the reason?

Thank

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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.

pohan likes this

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Hi @Ivan

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

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