Volume/Mass Constraint in the Model
In cases where volume/mass constraints are in the model, it is important to verify if the
corresponding constraint values are feasible with respect to the given FE-mesh size.
For example, if we consider a square plate that is discretized by 9 square elements
and use a relative volume constraint of 1/9, then we cannot expect a black and white
solution where some corners of the structure are connected. Set the
Minimize Volume/Mass as Objective
In cases where volume/mass is used as the objective function, follow the procedure recommendation
to avoid convergence issues. Check the displacements boundary conditions with
respect to the third direction if 3D models are used to simulate 2D structures.
Also, look for unwanted deformations and out of plane buckling. In cases where the
model uses displacement constraints, define these constraints at load application
and freeze regions around the displacement constraints. If the above setup does not help
to satisfy the constraints, then impose additional constraints on the structural
stiffness to stabilize the optimization. This is required to avoid structures acting
like compliant mechanisms. If solver convergence issues appear during the
optimization procedure, set Topology Optimization in the Context of Nonlinear Structural Analysis
The above setup is considered to be stable for running topology optimization of structures with
nonlinear behavior. Even though the settings consume more time for convergence, the
optimization can converge in the first attempt. The recommendation for the settings
is: small initial time increment, Manufacturing Constraints in the ModelIn cases where the model contains manufacturing restrictions:
Thermal Expansion in the Model For thermal expansion problems, the
recommendation is to use the Contact in the Model For highly nonlinear contact problems,
the automatic stabilization technique offered by the Abaqus solver is the recommendation. This option helps automatically control rigid body motion
before the contact closure restrains such motion, which can be activated by
Minimize Stress as ObjectiveIn cases where stress design responses are used to define the objective function, the recommendation is to give reference values for the corresponding design responses. If stress design responses are used in the model, the recommendation is to use sensitivities calculated by the Abaqus solver. |