Page 195 - Using ANSYS for Finite Element Analysis Dynamic, Probabilistic, Design and Heat Transfer Analysis

182 • using ansys for finite eLement anaLysis
5.2.4.3 Retrieve Results Parametrically

This is where we retrieve results data and assign them to parameters.
These parameters usually represent SVs and the objective function. The
*GET command (Utility Menu> Parameters> Get Scalar Data), which
assigns ANSYS calculated values to parameters, is used to retrieve the
data. POST1 is typically used for this step, especially if the data are to be
stored, summed, or otherwise manipulated.
In our beam example, the weight of the beam is the objective func-
tion (to be minimized). Since weight is directly proportional to volume,
and assuming uniform density, minimizing the total volume of the beam
is the same as minimizing its weight. Therefore, we can use volume as
the objective function. The SVs for this example are the total stress and
deflection. The parameters for these data may be defined as follows:
/POST1
SET,...
NSORT,U,Y ! Sorts nodes based on UY deflection
*GET,DMAX,SORT,,MAX ! Parameter DMAX = maximum
deflection
!
! Derived data for line elements are accessed
through ETABLE:
ETABLE,VOLU,VOLU ! VOLU = volume of each element
ETABLE,SMAX_I,NMISC,1 ! SMAX_I = max. stress at
end I of each element
ETABLE,SMAX_J,NMISC,3 ! SMAX_J = max. stress at
end J of each element
!
SSUM ! Sums the data in each column of the ele-
ment table
*GET,VOLUME,SSUM,,ITEM,VOLU ! Parameter VOLUME
= total volume
ESORT,ETAB,SMAX_I,,1 ! Sorts elements based on
absolute value of SMAX_I
*GET,SMAXI,SORT,,MAX ! Parameter SMAXI = max.
value of SMAX_I
ESORT,ETAB,SMAX_J,,1 ! Sorts elements based on
absolute value of SMAX_J
*GET,SMAXJ,SORT,,MAX ! Parameter SMAXJ = max.
value of SMAX_J
SMAX=SMAXI>SMAXJ ! Parameter SMAX = greater of
SMAXI and SMAXJ