With the Loads and Boundary Condition Tools all Boundary Conditions can be created which are required for the optimization. It can be chosen between Displacement Constraints and Structural Loads.
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The acceleration only affects the design space and doesn’t need to be applied on a cell or surface!
Attention: If only an acceleration and no other load is defined in the same load case, the optimization will get rid of the whole material. The acceleration force is directly dependent on the volume of the design space. As the design space is reduced so is the acceleration force until no material is left.