Learning Forum

[rafidison23]

Hello everyone,

Grateful if someone could help me configure the contact for this type of configuration.

The interface is bonded and breaks until Tmax followed by a classic friction phenomenon. My main problem is the drop since there are two conditions, should I use a CZM material?

Kind regards

[Wenlong]

Hi,

First, sorry about the late reply. I just saw your post. 

To get started, you can look into the "static and dynamic frictional coefficient" and "frictional decay". The information can be found here: https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v201/en/ans_ctec/Hlp_ctec_realkey.html%23africtioncoeffjjs62101229

This is a quite long page, but once you go to that page, search " 3.9.5.4. Static and Dynamic Friction Coefficients" and you will see the relevant information. I will come back to you later with an example. 

Note that in order to create some friction, you will need to make the diameter of the cylinder slightly larger than the hole. 

Regards,

Wenlong

================ Note ====================

If you have trouble opening the links I attached, please see the first useful link below

 

 

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Useful Links

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• How to access Ansys Online Help Document


• How to show full resolution image


• How to use Google to search within Ansys Student Community

 

[rafidison23]

Dear M.Wenlong,

Thank you very much for your reply, it's very helpful.

Where can I define FACT (or MU)? I know the experimental value of TAUMAX therefore FACT. I obtained the value of T-max by introducing µ in my simulation and by slightly increasing the dimension of the cylinder as you advised. However, the descent is not what I expected. Should I use a command for MU or FACT entry? if yes, could you tell me how to write it in the command?

Kind regards 

[Wenlong]

Hi,

Please see below. You can use RMODIF to change the real constant of contact element. Meanings of real constants are shown in this page: https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v201/en/ans_elem/Hlp_E_CONTA174.html.

In the RMODIF command, the first input "cid" and "tid" are the contact and target element identification number, the second input is the real constant number, and 9 means the 9th real constant, the last input is the value you assign to that real constant. 

Regards,

Wenlong

 

[rafidison23]

Dear M.Wenlong,

Thanks a lot for your response.

I followed your advice and have a drop but I still have a little problem. Indeed I modelled a hole (d=0.349mm h=1mm) and a cylinder (slightly larger than a hole 0.35mm) then apply a displacement (1mm). The bond must be maintained until TAUMAX (7.3MPa) and drop to 2MPa after the same.

I introduced µ=0.1 then in the (APDL) command TAUMAX (9), FACT(21) and DC(22) as follows:

RMODIF, cid, 9, 7.3

RMODIF, cid, 21, 3.65

RMODIF, cid, 22, 0

RMODIF, tid, 9, 7.3

RMODIF, tid, 21, 3.65

RMODIF, tid, 22, 0

I expected to have the same value of TAUMAX in my results but it is not the case. The result seems to be inappropriate and changes enormously as soon as I change a parameter (mesh size for example). Have I entered my command correctly?

Kind regards

 

[Wenlong]

Sorry I made a mistake. Please delete the TAUMAX real constant as it limits your max friction value. FACT and DC will be enough. 

Here is a similar simulation I run using FACT=3, DC=0, and mu=0.01

Regards,

Wenlong