# Switch contact to tie? **URL:** \ **Category:** General Questions\ **Created:** [July 22, 2022, 12:28pm UTC](https://prepomax.discourse.group/t/switch-contact-to-tie/317 "2022-07-22T12:28:41Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![lukerickert](https://avatars.discourse-cdn.com/v4/letter/l/53a042/32.png) [@lukerickert](https://prepomax.discourse.group/u/lukerickert)\ **Post date:** [July 22, 2022, 12:28pm UTC](https://prepomax.discourse.group/t/switch-contact-to-tie/317/1 "2022-07-22T12:28:41Z")
When I was working with Abaqus and doing models using contact I would usually create the contact relations and then start running the model with as many as of those relations tied rather than in contact, it was useful for finding issues, locating problems etc and made everything run quickly. Is there a straight forward way to do that in PrePoMax or perhaps to change the input file manually? thanks Luke ---
**Author:** ![FEAnalyst](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/feanalyst/32/688_2.png) [@FEAnalyst](https://prepomax.discourse.group/u/FEAnalyst)\ **Post date:** [July 22, 2022, 12:38pm UTC](https://prepomax.discourse.group/t/switch-contact-to-tie/317/2 "2022-07-22T12:38:20Z")
You can only change the type of interaction (contact/tie) displayed in the Search Contact Pairs tool’s window. But once it’s created, you have to replace it manually. If the Search Contact Pairs tool could show existing interactions, it would be possible to make such a change easily. Maybe a “Change to tie/contact” button next to “Swap Master/Slave” would be a good idea. ---
**Author:** ![synt](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/synt/32/4658_2.png) [@synt](https://prepomax.discourse.group/u/synt)\ **Post date:** [July 22, 2022, 1:06pm UTC](https://prepomax.discourse.group/t/switch-contact-to-tie/317/3 "2022-07-22T13:06:37Z")
> [@lukerickert](#): > > Is there a straight forward way to do that in PrePoMax hi, you can do it easily to switch between contact and tie using Tied Contact types. for coarser/medium mesh density it will give better result compared to Tie Constraint. also, Tied Contact type did not sensitive for cases inappropriate definition of master/slave in the models. best, ![2022-07-22 19_57_35-Create surface interaction](https://global.discourse-cdn.com/free1/uploads/prepomax/original/1X/7e7a3486d59d1ed68717ccb34d87283c650c667e.png) ---
**Author:** ![lukerickert](https://avatars.discourse-cdn.com/v4/letter/l/53a042/32.png) [@lukerickert](https://prepomax.discourse.group/u/lukerickert)\ **Post date:** [July 22, 2022, 1:11pm UTC](https://prepomax.discourse.group/t/switch-contact-to-tie/317/4 "2022-07-22T13:11:27Z")
thanks that is a good solution, I will give it a try. ---
**Author:** ![synt](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/synt/32/4658_2.png) [@synt](https://prepomax.discourse.group/u/synt)\ **Post date:** [July 22, 2022, 1:16pm UTC](https://prepomax.discourse.group/t/switch-contact-to-tie/317/5 "2022-07-22T13:16:29Z")
> [@FEAnalyst](#): > > Maybe a “Change to tie/contact” button next to “Swap Master/Slave” would be a good idea. right, this is could be useful features. ---
**Author:** ![Matej](https://avatars.discourse-cdn.com/v4/letter/m/a698b9/32.png) [@Matej](https://prepomax.discourse.group/u/Matej)\ **Post date:** [July 23, 2022, 3:18pm UTC](https://prepomax.discourse.group/t/switch-contact-to-tie/317/6 "2022-07-23T15:18:31Z")
> [@FEAnalyst](#): > > Maybe a “Change to tie/contact” button next to “Swap Master/Slave” would be a good idea. Well, I agree that this functionallity coud improve the user experiance. But there are some considerations. 1. As already mentioned, when using the Tie constraint one surface can only be a master surface once, othervise ther will be an error. The tied conctact deos not have this limitation. 2. Do we use the tied constraint of tied contact for the “change to TIE” command. 3. How to turn a tied constraint to a contact. Which settings to use for the cotnact. Maybe I coud add an option to change the contact to tied contact in a similar maner as is now done for Activate/Deactivate option. When in tie mode an additional icon could be shown. So the user shuld prepare all the contacts and then change them to Tied contact if needed. But it would not work in the opposite direciton. ---
**Author:** ![FEAnalyst](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/feanalyst/32/688_2.png) [@FEAnalyst](https://prepomax.discourse.group/u/FEAnalyst)\ **Post date:** [July 23, 2022, 3:45pm UTC](https://prepomax.discourse.group/t/switch-contact-to-tie/317/7 "2022-07-23T15:45:27Z")
I was thinking about converting to and from a tie constraint. Tied contact is indeed a very good equivalent (and works better than tie constraint in some cases) but it’s defined differently - by changing the contact property associated with interactions. So I think that a button converting regular contact to tied contact is not necessarily needed and could bring some confusion. A button converting to tie constraint would be the way to go in my opinion but you are right that some limitations have to be considered. So maybe if you add an option to display existing interactions in the Search Contact Pairs tool (like it is in Abaqus) at some point in the future, it will also become possible to change the type of these interactions. It seems to be the safest approach in this case.