supported
not supportedPTC® Creo® can be used to create a numerical FEA model, which can be exported into the FNF format to get a suitable source model for ProTOp. The FNF format supports:
Multiple load cases can be defined by defining multiple analyses. Note that ProTOp will import each analysis as a separate load case for the optimization procedure.
To prepare a ProTOp usable FEA model with PTC® Creo®, the procedure is roughly the same as preparing a usual FEA simulation model. More precisely, the following steps should done:
When PTC® Creo® is used to get the source model, two topics need special attention:
Although Creo does an excellent job when preparing the CAD and FEM model, two issues have to be kept in mind, if the FEM model has to be exported into the FNF format. These two issues are related to coordinate systems and total force loading.
It seems that the export of coordinate systems into the FNF model might be problematic under some circumstances. For this reason it is necessary that all
are defined exclusively in the global WCS coordinate system. Failure to do this can result in incorrect FNF data and incorrect import into ProTOp.
IMPORTANT. Use exclusively the global WCS coordinate system to define your CAD/FEM model.
If total force loading is used and the model has to be exported into FNF, there is one thing that needs attention: the total force load that is exported into FNF is applied separately to each surface of the container surface that was selected when applying the load.
When using the total force loading always check the loading resultant forces that are logged by ProTOp in the Optimization load cases dialog.
IMPORTANT. The total force load is applied separately to each surface of the selected container surface. Always check the loading resultants in ProTOp.
This section explains which options of PTC® Creo® are supported in ProTOp. For easier reading, the figures are decorated by the following symbols, denoting whether a particular option is supported or not:
supported not supportedThe FEA model preparation for optimization in ProTOP has to be defined in both, FEM and Structure modes. The Thermal mode for transient and steady state heat transfer analyses can not be used for optimization with ProTOp.
Figure. Creo's Home tab with marked Modes, Loads, Constraints, and other settings for the FE model preparation
A FEA model may consist of several volume and surface regions which shapes and number depend on the complexity of the model. Volume and surface regions are used to assign materials, loads, and constraints. Creo offers sub surface and volume regions definition in the Refine Model tab. Other available ribbons such as Idealization and Connections are not required when preparing a model for optimization with ProTOp.
Figure. Supported features in the Refine Model tab
The FE model from Creo is transferred to ProTOp by using the PTC FEM Neutral Format (FNF) file. Structural solid 3D multi-load-case analyses are supported by ProTOp. Modal (eigenfrequencies) analyses are not supported yet.
Figure. FEA export settings and options
Creo allows applying forces on a surface, edge or curve, and vertex or point. In this case the loads are defined by the total force or total force per unit area vectors in various forms. They can be constant or they can vary as a function of spatial coordinates.
Another option is to apply forces as total load at reference point. In this case the reference point and part geometry references are selected, and the force and moment vectors are defined at reference point.
Allowed options in Creo for Force/Moment Load:
The figure below shows the dialog box for force/moment load definition.
Figure. Force/Moment Load dialog box
These loads are defined on surfaces and sub-surface regions as a force per unit area acting in the direction normal to the surface. They can spatial vary as a function of coordinates.
Allowed options in Creo for Pressure Load:
The figure below shows the pressure load dialog box.
Figure. Pressure Load dialog box
Accelerations and/or Gravity loads are volume forces. In Creo they are defined for the whole part by the acceleration vector. Volume forces can be controlled by the material density for volume regions at given acceleration value.
Allowed options in Creo for Gravity Load:
The figure below shows the gravity load dialog box for acceleration vector definition.
Figure. Gravity Load dialog box
Centrifugal loads as a result of angular velocity are supported. They have to be defined by the angular velocity vector in the world (WCS) coordinate system only. Centrifugal loads as a result of angular acceleration are not supported.
Allowed options in Creo for Centrifugal Load (Angular Velocity only):
The figure below shows the centrifugal load dialog box.
Figure. Centrifugal Load dialog box
Structural temperature loading, defined by the prescribed difference between the given and the reference temperature, is supported. It can be prescribed either on a part, volume, surface, or edge/curve. It can spatially vary as a function of coordinates.
Allowed options in Creo for Structural Temperature Load:
The figure below shows the dialog box for temperature load definition.
Figure. Structural Temperature Load dialog box
Boundary conditions are defined by the displacement constraints imposed on a 3D solid continuum. The displacements/translations can be prescribed for a Surface, Edge/Curve, and Vertex/Point. The displacement component options are free, fixed, and prescribed displacement value in the given coordinate direction. Rotation constraints can not be used for 3D solid finite elements.
Allowed options in Creo for Displacement/Constraint (Translation only):
The figure below shows the dialog box for constraints.
Figure. Constraint dialog box
Planar, Pin, and Ball boundary conditions are also supported by ProTOp. The Planar Constraint prevents displacements in the direction being normal to the plane; in-plane displacements are allowed.
Figure. Planar Constraint dialog box
The Pin Constraint prevents displacements in the direction being normal to the cylindrical surface; optionally, displacements in the circular and/or axial direction of the cylindrical surface are also prevented.
Figure. Pin Constraint dialog box
The Ball Constraint prevents displacements in the direction being normal to the spherical surface.
Figure. Ball Constraint dialog box
Isotropic linear elastic material behavior is supported by ProTOp. It can be defined on a component/part or on a volume region. Each volume region can have its material properties.
The figure below shows the dialog box for the material definition.
Figure. Material Definition dialog box
Topology optimization requires fine meshes with uniform element sizes and undistorted shapes to obtain high quality optimization results. Adequate maximum element size is recommended to be prescribed for the entire part. The maximal element size has to be small enough so that each structural member can accommodate at least 3 finite elements in the thickness direction. Linear tetrahedral elements are generally recommended because of low RAM and CPU time consumption.
The figure below shows the dialog box for element size control.
Figure. Element Size Control dialog box