SIMULIA Tosca Structure
avoids problematic eigenfrequencies in dynamic problems with a special MINMAX formulation.
Here, the object function
for eigenfrequencies by TARGET= MINMAX is given:
By minimizing this expression, the eigenfrequencies f will be moved away from the value of
.
With
as a constant, the SIMULIA Tosca Structure commands are:
DRESP
ID_NAME = dresp_eig_1
DEF_TYPE = SYSTEM
TYPE = DYN_FREQ
LC_SET = Modal,All,1
END_
...
DRESP
ID_NAME = dresp_eig_20
DEF_TYPE = SYSTEM
TYPE = DYN_FREQ
LC_SET = Modal,All,20
END_
OBJ_FUNC
ID_NAME = move_dresp_eig_from_15Hz
DRESP = dresp_eig_1, 1.0, 15.
...
DRESP = dresp_eig_20, 1.0, 15.
TARGET = MINMAX
END_

|
Convergence of eigenvalues of a bandgap optimization (15 Hz) |
The second eigenmode will be pushed away from 15.0 Hz. The weighting of the design response is 1.0.