Remarks for Sensitivity-Based Optimizations

Prescribed Accelerations for Sensitivity-Based Optimization Using Tosca Response Values and Sensitivities

Prescribed acceleration loading is often caused by gravity fields, centrifugal loading, and rotary acceleration loads. This chapter defines which kinds of acceleration types for the ANSYS® are feasible for sensitivity-based topology and sizing optimization. These acceleration types are not supported for shape and bead optimization.

The following commands are supported (In global Cartesian directions):

ACEL specifies the linear acceleration of the structure.
OMEGA specifies the rotational velocity of the structure.
DOMEGA specifies the rotational acceleration of the structure.

The following commands are supported (About another reference coordinate system):

CGLOC specifies the origin location of the acceleration coordinate system.
CGOMEGA specifies the rotational velocity of the global origin.
DCGOMG specifies the rotational acceleration of the global origin.

The following commands are supported (For element components):

CMDOMEGA specifies the rotational acceleration of an element component about a user-defined rotational axis.
CMOMEGA specifies the rotational velocity of an element component about a user-defined rotational axis.

Note:

Applying lumped mass matrices can be enforced using LUMPM,OFF
Applying consistent mass matrices can be enforced using LUMPM,ON

Multi CPU-Processors (MPI) in Combination with Sensitivity-Based Topology Optimization

Tosca Limitations:

Important:

There are ANSYS® elements (for example, MPC184) that are not supported during ANSYS® MPI (or the so called Distributed ANSYS) run. Those elements are not allowed when using Tosca with ANSYS® MPI.
There are ANSYS® commands (for example, PSOLVE, ELFORM) that are not supported during ANSYS® MPI run. Thus ANSYS® fails to deliver all results requested by Tosca Structure sensitivity-based topology optimization when an ANSYS® analysis is executed in Distributed mode in combination with Tosca Structure sensitivity-based topology optimization. ANSYS® failing to deliver all results requested by Tosca Structure sensitivity-based topology optimization is solved by adding the following in the OPT_PARAM command in the ".par" file,


OPT_PARAM
  ....
  PROCESSORS = MULTI
  ....

END_

Default is PROCESSORS = SINGLE.
Design responses for reaction forces and internal forces cannot be applied when PROCESSORS = MULTI is activated.

Nonlinear Sensitivity-Based Optimizations (ANSYS® 14 Required)

Displacements, internal and reaction forces, and stress values (that is, all design responses except for compliance) extracted from nonlinear static analysis require information (pseudo loads) from ANSYS® perturbation steps for sensitivity-based optimization. These perturbation analyses are only available in ANSYS® 14 or newer and allow for the elements enlisted in the table below.

Important:

Nonlinear optimizations using pseudo loads with ANSYS® versions < 14 are no longer supported. If you want to use this kind of optimizations, make sure you are using at least ANSYS® 14.

Linear perturbations in ANSYS® currently only allow the following element types:


Category	Element Name
Spars	LINK180
Beams	BEAM188 BEAM189
Pipes	PIPE288 PIPE289
2D Solids	PLANE182 PLANE183
3D Solids	SOLID185 SOLID186 SOLID187 SOLID285
Shells	SHELL181 SHELL208 SHELL209 SHELL281
Solid-Shell	SOLSH190
Interface	INTER192 INTER193 INTER194 INTER195
Contact	TARGE169 TARGE170 CONTA171 CONTA172 CONTA173 CONTA174 CONTA175 CONTA176 CONTA177 CONTA178
Specialty Sizing Optimization for Circular Beams	COMBIN14 MASS21 MATRIX27 COMBIN39(*) SURF153 SURF154 SURF156 PRETS179 MPC184 MESH200 FOLLOW201 COMBI214 HSFLD241 HSFLD242
(*) support of this element type will be added in ANSYS® 14.5

Important:

Other element types are not allowed in the model for nonlinear optimizations using pseudo loads in Tosca Structure.