NX Nastran DMAP Programmer's Guide - Kxcad.net

GPFDR
Computes grid point forces and element strain energy
TINY Input-real-default=1.E-03. Small element strain energy value. Element
strain energies less than TINY will not be printed.
XFLAG Input-integer-default=0. Strain energy method selection.
Remarks:
1. GPFDR creates the grid point force balance table for a user-selected set of points.
This table lists the forces acting at each selected point due to element constraints,
single-point constraints, and applied loads. Also listed is the sum total of these
forces which represents the balance in an opposite direction due to multipoint
constraints, general elements, round-off errors, and other nonlisted sources.
Subtotals for element sets and element types are also provided.
2. GPFDR creates the element strain energy table for a user-selected set of elements.
These selected elements are listed by type with their strain energy, percent of total
strain energy with respect to all elements and strain energy density. The strain
energy is computed by one of the following equations:
If XFLAG=0 (default):
If XFLAG=1:
0 Elemental force
1 Cross displacement. See Remark 2.
CYCLIC Input-logical-default=FALSE. Set to TRUE for cyclic symmetry models.
WTMASS Input-real-default=1.0. Specifies scale factor on elemental mass matrix.
⎧ 1⎫
⎨ue⎬ ⎩ ⎭
W e
W e
=
=
1
-- { F
2 e}
T { ue }
1⎧
1 ⎫⎧ T ⎫⎧ i ⎫
-- u
2
⎨ e ⎬⎨Ke⎬⎨ue⎬
⎩ ⎭⎩
⎭⎩
⎭
where is the displacement for the first subcase or mode and
⎧ i ⎫
⎨ue⎬ ⎩ ⎭
where is the displacement for the i-th subcase or mode.
Eq. 4-17
Eq. 4-18
3. The strain energy density is computed by dividing the strain energy by the
element volume. The total energy is computed by summing the element strain
energies of all elements for which stiffness matrices exist. General elements are
not included.
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