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How to set up contact for two bodies with zero Gap

Dear everyone,

I have some problems about setting up contacts for two bodies with zero Gap at initial time. Type 7 was used, and two brick solid components were set for slave and master. An error message was received as follows:

INTERFACE NUMBER. . . . . . . . . . . . . . 2
INTERFACE TYPE. . . . . . . . . . . . . . . 7

GAP MIN = 0.3000000000000
POSSIBLE IMPACT NUMBER: 77 (<= 1 *NSN)
** INITIAL PENETRATION = 0.3000000E+00 IMPOSSIBLE TO CALCULATE NEW COORDINATES OF SLAVE NODE 380483

ERROR ID : 612
** ERROR IN INITIAL PENETRATION IN INTERFACE
DESCRIPTION :
-- INTERFACE ID : 2
-- INTERFACE TITLE : DiPao_WaLengZhi
INACTI = 0
SLAVE NODE 380483 IS ON THE MASTER SURFACE
** INITIAL PENETRATION = 0.3000000E+00 IMPOSSIBLE TO CALCULATE NEW COORDINATES OF SLAVE NODE 377618

How to deal with this problem? Could anyone give some advice? Thank you!

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Altair Forum User

Hi Roy,

If there is no relative motion or sliding between the master and slave components you can try defining a Type 2 interface, which kinematically connects a set of slave nodes to a master surface. Else if you are going with Type 7 interface, provide a Gapmin value (small value). And also, please clear the penetrations in the model and use Inacti=6.

If you still face trouble, please share the model file.

Altair Forum User

Hi Roy,

If there is no relative motion or sliding between the master and slave components you can try defining a Type 2 interface, which kinematically connects a set of slave nodes to a master surface. Else if you are going with Type 7 interface, provide a Gapmin value (small value). And also, please clear the penetrations in the model and use Inacti=6.

If you still face trouble, please share the model file.

Dear George P,

Type 7 interface must be used because of relative motion between the two brick components. In fact, there is no penetration for mesh at initial condition (the Gap is zero). I think penetration is detected because a none zero contact Gap is always exist for contact definition in Radioss.

However, this is a common case for two bodies with zero Gap at initial time in real world. So how to set up contact for this situation in Radioss ?

I hope I express clearly. By the way, what's your meaning for ' clear the penetrations in the model '?

Best wishes

Roy Duan

Altair Forum User

Hi Roy,

Did you provide a Gapmin value?. If not, please provide a Gapmin and try running.
From Tool Menu, select penetration and check the model for any penetrations. Please share the starter out (_0000.out) file.

Altair Forum User

Hi Roy,

Did you provide a Gapmin value?. If not, please provide a Gapmin and try running.
From Tool Menu, select penetration and check the model for any penetrations. Please share the starter out (_0000.out) file.

Dear George P,

Thank you for your reply.

I have tried a small Gapmin value, however it is still terminate with same errors as before. The physical gap of the two solid parts is zero at initial time. I think this initial contact condition is common in real world, and I believe Radioss can be used for this usual problem. So how to set up the correct contact type and contact parameters ?

The input file and starter out file have been attached. Can you help me? Thank you!

Best wishes

Roy Duan

Unable to find an attachment - read this blog

Altair Forum User

Hi Roy,

Please check the model attached.

Unable to find an attachment - read this blog

Altair Forum User

Hi Roy,

Please check the model attached.

Dear George P,

Could you please export the input file with a lower version? My solver only support version below 120. In addition, can you explain how do you solve this problem? Thanks.

ERROR ID : 266
** ERROR IN INPUT FORMAT
DESCRIPTION :
INPUT VERSION 140 IS NOT SUPPORTED

Best Wishes!

Roy Duan

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Altair Forum User

Hi,

Please find the model file. There were many penetrations in the model which were cleared.

Meanwhile, I recommend you to update to HyperWorks 14.0 Version. Please visit http://www.altairuniversity.com/get-the-free-hyperworks-14-0-student-edition/ for installation.

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Altair Forum User

Hi,

Please find the model file. There were many penetrations in the model which were cleared.

Dear George P,

The problem seems to be solved. However, in my initial model, the normal distance of the nodes on contact surface is zero (The model was built with zero physical gap, and I confirmed it in hypermesh by using distance command). So why you said there are many penetrations in the model? And how does the penetration come from?

Best Wishes!

Roy Duan

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Altair Forum User

Hi Roy,

There was an intersection in your model and contact penetrations.Solid entities overlap between solids registers as intersections, because one or more of each the solid’s faces intersect. Intersection is defined as elements that actually pass completely through one another.

I recommend you to go through HM-3320: Penetration tutorial in the Help Menu where it will show how to check penetrations and fixing the penetrations and intersections in a model.

Altair Forum User

Dear George P,

Thank you for your recommendation. From penetration check, I found only one Intersections but with none Penetrations. Attachments are the penetration check set up and check result. Is there any errors?

From this example, does it mean Radioss cannot be used for zero physic gap contact problem? In my test model, the initial physical gap is exactly zero, but Intersections was detected by using penetration check, and this Intersections result in error for running.

Best Wishes

Roy Duan

Altair Forum User

Hi Roy,

When a contact is established there are chances of intersections and penetrations on interfaces, as in your case. This penetration at the contact interface has to be cleared before running these kinds of zero contact gap problems. Penetrations can result in dropping the time step and thereby the run will be terminated.

For clearing penetrations in contact, we have a tool in HyperCrash. The rad file is imported in HyperCrash and the contact interfaces are checked for any penetrations and using the depenetration option these are removed.

Please go through the Contact in HyperCrash from Help Menu where much details are provided about this.

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

Altair Forum User

Dear George P,

Thank you for your reply. It seems that this contact problem can be solved with Type 20 (Igap=1) without do anything else to the model.

Maybe Type 7 is not appropriate for this zero gap problem. But I don't understand what's the difference between Type 7 and Type 20.

Best Wishes.

Roy Duan