About the Shaft Turn Example | ||
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About the Model
For rotational symmetrical components, a nonsymmetrical shape should not be generated in the optimization. Therefore, the design nodes must be linked in a symmetrical way. For rotation symmetrical meshes, the standard link formulation in Tosca Structure might be used. If the meshes are not rotational symmetrical (what is often the case in tetrahedron meshes) the mesh-independent or geometrical approach in Tosca Structure must be used to maintain symmetrical behavior. The following figure illustrates the boundary conditions and the stress distribution of the initial model.
Segmentation into link groups is impossible for arbitrary meshes. The parameter SURF_TURN in the LINK_SHAPE command is used to define the restriction. This geometric approach allows the definition of turning restrictions for any finite element mesh. The rotation curve is determined automatically by the optimization system. The user only must define a surface node group that specifies the turn surface and the rotation axis using a coordinate system.
The definition of the following groups is required for the optimization task:
Procedure Summary
| Model: | shaft_turn.ext |
| Design Area: | Node group design_area |
| CS_DEF | New cylindrical coordinate system, defined by rotating the global CS by 270° around the global x-axis |
| Design Variable Constraint: | Apply boundary conditions for all nodes |
| Design Variable Constraint: | Turning restriction for node group geo_area1 in direction of the global positive y-axis |
| Design Variable Constraint: | Fixation of the displacement along the global y-axis for the node group fix_area |
| Design Variable Constraint: | Fixation of the first (radial) coordinate (in the new cylindrical coordinate system) of the displacements for the node group cylinder_circle |
| Mesh Smooth: | Mesh smoothing of all elements, while free surface nodes remain free |
| Objective: | Minimize the maximal von Mises stresses in the design area |
| Settings: | Read boundary conditions for all nodes |
| Stop Condition | The global stop condition is set to 6 iterations |