If your Nondesign spaces are tearing off, your result looks something like the picture below.
If a boundary condition is applied on one of these Nondesign spaces an error will occur and the optimisation will stop. The model is no longer complete and it doesn’t make sense to continue with the optimisation.
If no boundary condition is applied on one of these Nondesign spaces, a warning will occur but the optimisation will continue.
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Reasonswhy the Nondesign spaces are tearing off:
either no force or displacement is applied → no stresses are available for the stress optimization optimisation to prevent the material from being reduced
or the force applied is too small
or the additional fixation is not needed for the defined boundary conditions and optimization constraintsoptimisation constraints
If you are using the symmetry function with the whole model, the optimiser won't use the symmetrical Nondesign spaces and will notify you thereof - don’t worry everything is just as it is supposed to be
Steps to prevent this behaviour:
Either it is a design proposal you can accept/want to achieve in order to reduce the number of fixation points
Or prevent Prevent the tearing off by:
increasing the Complexity → more elements are available and a finer model is possible (calculation effort increases!)
reducing the optimization the optimisation stress goal
increasing the applied force so that the stresses and therefore the relevance of the nondesign Nondesign space is increased
creating an extra load case in which fixations and loads are switched
If you are using the symmetry function with the whole model, the optimizer won't use the symmetrical nondesign spaces and will notify you thereof - don’t worry everything is just as it is supposed to be Either it is a design proposal you can accept/want to achieve in order to reduce the number of fixation points
To reduce the number of fixations, the fixation has to be applied on all Nondesign spaces at once as one boundary condition (multi-selection)
Thus individual Fixations can tear off without an occurring error
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Boundary condition multiselection of Nondesign spaces to enable tearing off of Fixations.