The opposite of the former approach might also be the case—that is to force an eigenfrequency to
achieve a certain value. This might be realized using constraint functions.
DRESP
ID_NAME = dresp_eig_2
DEF_TYPE = SYSTEM
TYPE = DYN_FREQ
LC_SET = Modal,All,2
END_
OBJ_FUNC
ID_NAME = max_dresp_eig_2
DRESP = dresp_eig_2
TARGET = MAX
END_
CONSTRAINT
ID_NAME = con_dresp_eig_2_le_15Hz
DRESP = dresp_eig_2
MAGNITUDE = ABS
LE_VALUE = 15.
END_
OPTIMIZE
ID_NAME = opt
DV = my_design_nodes
STRATEGY = BEAD_SENSITIVITY
OBJ_FUNC = max_ dresp_eig2
CONSTRAINT = con_dresp_eig_2_le_15Hz
END_
The second eigenmode will be maximized, but because of the constraint
it might not become higher than 15. Hz.