Basic Rules about assemblies in Creo Simulate:
Solid Element Models…
The default interface condition between parts in an assembly is that any surface geometry, between parts, that touch each other are assumed to be ‘bonded’. This means that for structural simulations (static and modal) the displacements are connected and continuous across the interface and for thermal simulations you have perfect heat conduction across the interface.
There are other possible conditions that may be defined. For structural simulations you can define the interface to be ‘free’. Free conditions allow the two surfaces pull away or pass through each other. In thermal simulations the interface may be defined as ‘adiabatic’ with no heat flow through the interface. One part is not affected by the other at the interface. Obviously, surfaces that do not touch in an assembly are treated as free and adiabatic by default.
For static simulations you can define ‘contact’ conditions. Contact allows the two surfaces to pull away from each other but does not allow penetration. With contact you may also define friction behavior or allow the surfaces to slide freely. Note: if ‘contact’ is defined in a modal simulation it is treated as a ‘free’ condition. Contact is not supported for modal or dynamic simulations.
For thermal simulation the interfaces may be defined as a ‘thermal resistance’. This may be useful in modeling contact resistance or even thin glue layers that are not practical to physically model.
For static problems, one may ask, why not always assume contact? That would seem to be more realistic, and in many cases it may be, however, models with ‘contact’ defined become nonlinear which can increase the solution times significantly. If you can assume a ‘free’ or ‘bonded’ conditions and still get sufficient accuracy, your solution times and the versatility of the model will improve.
Contact interfaces may also be defined between surfaces that do not touch in a part or in an assembly. Initially, two surfaces may be close to each other but not in contact. As the load is applied, they may deform such that they will touch.
In addition to ‘contact’, you may also define a ‘rigid link’ connection between geometric entities. Whatever entities are connected this way, the selected entities will behave as a rigid body. This may be used to connect two parts together or it may be used to simulate the effect of one part acting upon another without actually modeling both parts, thus simplifying the model.