Creo Simulate > Modeling Structure and Thermal Problems > Idealizations > Shells > Midsurface Shells > Before You Define a Shell Model > Model Entities and Idealizations
Model Entities and Idealizations
Creo Simulate supports the same modeling entities and idealizations for both solid and shell models. However, because Creo Simulate redefines geometry during midsurface compression, you need to exercise care when placing these items. Be aware of the following factors when planning modeling entities and idealizations for shell models:
Point measure applied on top or bottom surface of the midsurface shell is projected to the compressed geometry and is equivalent to a point measure applied on the shell idealization.
You cannot place certain types of loads or constraints on entities whose type changes when Creo Simulate compresses the model. The loads and constraints that fall into this category are loads distributed or applied based on unit type.
For example, a force load with a distribution of Force Per Unit Length or Force Per Unit Area falls into this category, but a force load applied with a Total Load distribution does not. Other types of loads and constraints in this category include interpolated loads, bearing loads, heat loads distributed based on unit type, pressure loads, and convection conditions.
Following are examples of entity-type changes that invalidate these types of loads or constraints:
compressing a loaded or constrained surface to a curve. There is one exception—surface constraints that have fully fixed translations with no prescribed displacements. In this case, Creo Simulate compresses the surface constraint to an edge constraint whose translations and rotations are fully fixed.
compressing a loaded or constrained surface region to a partial curve, unless you applied the load or constraint to the curve instead of the region as a whole
compressing a loaded or constrained curve to a point
For example, if you decide to model a rectangular plate as a shell, Creo Simulate would ask you to redefine the problem load.
If you place regional loads on both pair surfaces and those loads overlap, Creo Simulate calculates the overlapping area by adding or subtracting the load values and directions for the two regions.
Creo Simulate maintains constraints applied to overlapping regions.
If you place a constraint or load on a region and omit the region when you define your pairs, the software may not include that constraint or load. In this case, Creo Simulate displays a warning message when you try to analyze the model.