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Roy Duan

How to define a proper contact for a nonlinear analysis?

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Hi all,

1、For a problem with large deformation, the contact status between two objects will change. Some location will come into contact while some other location will separate. What's more, relative sliding may also exist. How to choose the proper parameter values in contact property card for this problem?

2、If a linear static analysis is chosen, could the contact status change during deformation process?

2018-05-31_175629.png.a762feb9bf439410582867866d3bba4f.png

 

Roy

 

 

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Hi Roy,

For linear static analysis the contact status Do not change and the Contact stiffness is constant through out.

I would suggest you to proceed With NLSTAT with LGDISP for your case

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15 hours ago, Nachiket Kadu said:

Hi @Roy Duan 

If you have access to help,i recommend you to refer contacts under user guide. It will answer all your queries in detail.

Hi @Nachiket Kadu

I have read the Pcont card in the user manual. However, some questions were still confused to me.

2018-06-01_112147.png.ce649b8a269a438e99ca83620006e43a.png

When MU1=STICK, does this mean the contact cannot separate with only sliding? Could the contact status change?

When MU1=FREEZE, does this mean the contact cannot separate and without sliding? Could the contact status change?

 

Roy

 

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17 hours ago, Karthic said:

Hi Roy,

For linear static analysis the contact status Do not change and the Contact stiffness is constant through out.

I would suggest you to proceed With NLSTAT with LGDISP for your case

Hi @Karthic

Is there any example about NLSTAT With LGDISP? Both nongeom and contact nonlinearity are considered.

 

Roy

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Hi @Roy Duan,

Geometric and material nonlinearity considered in below

OS-T: 1510 Follower Loads, Nonlinear Adaptive Criteria, and Nonlinear Intermediate Results

 

For STICK contact, master and the slave can separate once the contact has been closed. Stick contact interfaces will not enter the sliding phase.

Freeze Contact enforces zero relative motion on the contact surface, the contact gap opening remains fixed at the original value.

 

 

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@Roy Duan

Further, The "contact status change" which is being refered in Reference is with regards to OPEN or CLOSED contacts. Generally for frictional contact stiffness will be evaluated using element and material property of master and slave. So two stiffness will be evaluated as in for OPEN condition and CLOSED condition. When the contact realize the interaction between master and slave, CLOSED stiffness will be applicable or else OPEN. OPEN stiffness value will be very low. The stiffness you get to chnage using PCONT card depends on the behaviour of your simulation. In general use the default setting. If you find any convergence issue you may try go for soft contact. If you find uncessary intersection between master and slave you can use hard.

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1 hour ago, Karthic said:

Hi @Roy Duan,

Geometric and material nonlinearity considered in below

OS-T: 1510 Follower Loads, Nonlinear Adaptive Criteria, and Nonlinear Intermediate Results

 

For STICK contact, master and the slave can separate once the contact has been closed. Stick contact interfaces will not enter the sliding phase.

 Freeze Contact enforces zero relative motion on the contact surface, the contact gap opening remains fixed at the original value.

 

 

Hi @Karthic

As you said, 

For STICK contact, master and slave may separate but no relative sliding. While for Freeze contact, both normal motion and sliding are not allowed. Right?

 

Roy

 

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23 minutes ago, Roy Duan said:

While for Freeze contact, both normal motion and sliding are not allowed. Right?

To better understand, relative motion is zero in any direction, 

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