Mechanica cannot resolve certain topological conflicts when it meshes a model. While your part may appear topologically sound at the modeling stage and may mesh successfully during analysis, it may experience unacceptable topological changes when you change its shape during a sensitivity or optimization study. You can inadvertently introduce this type of problem during design parameter or feature creation.

Design parameters can cause problems if the movement of one parameter conflicts with that of another or conflicts with the natural boundaries of the part. When adding design parameters to a part, be sure that the ranges you define do not change part topology by introducing interference between features or part boundaries. You should take special care with features created by patterning or dependent mirroring.

Additionally, use special care when creating geometry using blends and sweeps. Both of these part building techniques may restrict the movement of your part and make new shapes difficult for Mechanica to mesh during a sensitivity or optimization study. Here are some tips for using blends and sweeps:

blends — Avoid building complex, multiple blends one on top of another. Mechanica may have trouble resolving the blends if the shape change twists the multiple blends in relation to one another.

sweeps — You can introduce meshing problems if you create the sweep using highly complex datum curves or irregular section-to-section transitions. Sweeps with either of these characteristics are more likely to develop topological wrinkles as Mechanica changes their shape and may fail to mesh. To avoid this, you can use advanced surfacing techniques in Pro/ENGINEER to smooth the topology of the section transitions.

To test for topology interference, animate or review your shape changes using the Analysis>Mechanica Design Controls>Shape Animate and Analysis>Mechanica Design Controls>Shape Review commands in Mechanica prior to starting your design study. Start with smaller shape changes to make sure the shape changes are realistic before specifying the full range of movement.

In addition to interference and topology problems caused by complex blends and sweeps, be aware that topology changes can introduce the following situations:

Mechanica may experience conflicts between existing loads. In this case, the software may modify one of the loads as a result of the conflict.

If the topology change is large and sudden, as with the dynamic suppression or addition of a feature through Pro/PROGRAM, the change may affect the quality of the optimization. The sudden introduction or removal of a feature can increase stresses in such a way that the optimizer stops prematurely, assuming that it has found a lower-stress design immediately prior to the topology change.

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