contact vs interface

[anandms]

hello everyone,


can anybody give me some information on contacts and interface in pro-mechanica.


whats the difference between them. when a contact or an interface can be used


thanks in advance

 

[jabbadeus]

Contact regions are used to define surfaces that can come into contact with one another between different components in an assembly due to applied loads and/or motion. Contact region analysis uses non-linear solutions because the contact pressure and area are not directly proportional to applied load. Contact regions also have options that allow you to specify number of intervals (to graph contact pressure as a function of load) and localized mesh refinement (change the mesh as the surfaces come into contact). Contact regions can also be applied to components that have interference fits and can be used to simulate drop tests.


Interfaces are used to change the mesh between components that are mated or touching in an assembly. By default, if two surfaces of two components are coincident with one another, when Mechanica generates the mesh, the nodes are combined. By using an interface, you can prevent the nodes from being combined. It's all about how you want to simulate forces and displacements from being transferred from one component to another.


Dave Martin

 

[anandms]

hello,


thank you for the information. if we do not use interface or contact between the assembly parts( of different materials also) it works as a single component. so it means if we use interface between parts in an assembly there may be penetration between the surfaces. is that right?


regards

 

[headrush]

Excellent question and answer. I believe this is how it works, but I am not an expert and we need a more knowlegable user to confirm this.


If two solid parts of an assembly have an interface (two surfaces) with the same dimensions the two parts are bonded by means of merged nodes.


If youcreate an "interface" on the interface surfaces, the nodes will not me merged and the parts are free to penetrateor move relative to each other


Shell elements are more complicated and I have not used them so I do not know how they work with regards to bonding.


The tricky part is knowing how much or how littleinterference or space between two surfaces results in the surfaces being bonded. Regarding this I have only the following information: "...ProE will still mesh the assembly (i.e. merge the nodes to create bonded surfaces) if the global intereference volume is very very low, up to three decimal places (0.0002cubic in.)" which I copied from this post: [url]http://www.mcadcentral.com/proe/forum/forum_posts.asp?TID=30 658&PN=3[/url]


Most meshers will merge (or not) based onthe distance between nodes, which is the distance between two surfaces. It would be nice to know the distance limit betweentwo surfaces whichwill resultin merged nodes.