# Calculix Ok for sails simulation: membrane+beams+interactions? **URL:** \ **Category:** Uncategorized\ **Created:** [February 27, 2022, 12:00pm UTC](https://calculix.discourse.group/t/calculix-ok-for-sails-simulation-membrane-beams-interactions/1009 "2022-02-27T12:00:06Z")\ **Posts on this page:** 1\ **Showing post:** 7
**Author:** ![Calc\_em](https://avatars.discourse-cdn.com/v4/letter/c/43a26b/32.png) [@Calc\_em](https://calculix.discourse.group/u/Calc_em)\ **Post date:** [February 28, 2022, 9:52pm UTC](https://calculix.discourse.group/t/calculix-ok-for-sails-simulation-membrane-beams-interactions/1009/7 "2022-02-28T21:52:34Z")
Contact can work also when the parts don’t touch initially. Once you specify that two surfaces are in a contact pair and define the behavior in both directions (normal and tangential) the software will automatically detect whether these surfaces are in contact or not. So they can start as separated, then come into contact (and the forces will be properly transmitted through the contact interface), then separate again or slide on each other due to applied load and so on. The only problem with such cases is that convergence issues may occur in a static analysis if the model relies on contact to eliminate rigid body motions. But you could use a dynamic analysis or apply some tricks (such as displacement control) in such a case. I don’t use MPCs in CalculiX but they can be (and often are) nonlinear and are able to model quite complex interactions so maybe they could help in this case as well. After all, they are sometimes used in place of contact: > [@Modeling surface contact with point-to-point linear contact](https://calculix.discourse.group/t/modeling-surface-contact-with-point-to-point-linear-contact/874): > > Hi, I’m following the book “Practical Finite Element Analysis for mechanical engineers”, and in section 14.7.2 I find an example where the base of a fitting is in contact with a plate and this contact is modeled as a point-to-point linear contact: All the nodes of the fitting’s base have their own MPCs. The plate is not represented in the model, the MPC linear contacts are grounded. I’m using PreProMax for the FEM except for the MPCs. The CalculiX manual mentions in point 6.7.2 th… --- _[View the full topic](https://calculix.discourse.group/t/calculix-ok-for-sails-simulation-membrane-beams-interactions/1009)._