Optimization Task

In Tosca Structure, a sensitivity-based approach is used for solving sizing problems. This algorithm uses the sensitivities of the design variables regarding the objective function and the constraints. Tosca Structure uses an algorithm based on the Method of Moving Asymptotes from Krister Svanberg (Sweden). In one optimization run approximately 10 to 15 iterations are required - much fewer compared to the sensitivity-based approach for topology optimization. The number of iterations as well as the CPU-time is independent of the number of shell element thicknesses chosen as design variables.

This page discusses:

Analysis Types

Tosca Structure.sizing supports the responses of linear static (nonconservative forces) and linear eigenfrequency (not allowed to be prestressed) finite element analysis. Temperature loading is allowed for Abaqus and ANSYS®.

Nonlinearities

Contact for Abaqus and ANSYS® is supported in- and outside the design area.

All types of constitutive nonlinear modeling are allowed; for example, a nonlinear spring. Geometrical nonlinearities are also supported.

Tosca Structure.sizing supports contact for Abaqus and ANSYS®.

In addition, prescribed displacements are allowed in the CAE model for static sizing optimization. However, prescribed displacements are not allowed for modal and frequency response analysis.

Model

Tosca Structure.sizing supports only single layered shells (admitted for sensitivity-based optimization).

In addition, “constant” temperature loading is supported.

Allowed Objective Functions and Constraints

For sizing optimization, a variety of combinations of objective functions and constraints can be selected

  • Static load cases: Stiffness (= compliance), Displacements, Forces
  • Modal eigenfrequency load cases: Eigenfrequencies
  • Frequency response, including vibroacoustic
  • Mass

Several constraints and several terms for the objective function for an arbitrary number of load cases can be specified.