Topology optimization: continuity of material in design area

Francesco Porcari

Hi everyone,

I tried to do a topology optimization of a piece made of one design and two non-design areas. I want this body to reach knew mass, inertia yy and x coordinate of cog (enter certain tolerances).

The simulation runs successfully, but in the design area there is a non continuity of material as you can see in figure attached, so a part of the piece it's fluctuating in void. 

Any idea for create continuity of material? I tried to set mindim and maxdim in desvar paramter, but no results. Maybe the design area was too large, so I can reduce it to force the creation of continuity, but I think this isn't the most elegant method... I attach also the .fem if you want to look it

 

Thanks

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link.fem

PaulAltair

The objectives and constraints are not well posed I think to get what you are looking for.

The constraint on CofG is requiring most of the material to be to the left of the constrained non-design area as we look at it, but since the loadpath from load to bcs is all between the 2 non design areas, adding material to the left does nothing really to aid the objective to reduce compliance, so OS is basically just creating a lumped mass on the left to move your cog to the requested location (somewhere to the left of the constraint) in order to meet the CofG constraint alone, this section is still joined to the whole (just with low density elements) if you want a continuous load path to the left, there needs to be some reason for it to exist (e.g. a displacement constraint or some other aim, below is with a disp constraint on the left hand end, but it likely isn't what you are after either, it effectively forces compliance up conflicting with your primary objective) 

What is the reason for constraining CofG to be on the left of the 'useful' material?