DTPG
Bulk Data Entry Defines parameters for the generation of topography design variables.
Format
(1)  (2)  (3)  (4)  (5)  (6)  (7)  (8)  (9)  (10) 

DTPG  ID  TYPE  PID1/ SID1 /DVID 
PID2/ SID2 
PID3/ SID3 
PID4/ SID4 
PID5/ SID5 
PID6/ SID6 

PID7/ SID7 
etc  etc  etc  etc  etc  etc  
MW  ANG  BF  HGT  Norm/ XD 
YD  ZD  SKIP  
MAXW  MAXWTH  MINHGT  ZEROB  
PATRN  TYP  AID/ XA 
YA  ZA  FID/ XF 
YF  ZF  
PATRN2  UCYC  SID/ XS 
YS  ZS  
BOUNDS  LB  UB  INIT  DDVAL  
AUTOBEAD  LAYER  REMESH 
(1)  (2)  (3)  (4)  (5)  (6)  (7)  (8)  (9)  (10) 

MAIN  
COORD  CID  CAID/ XCA 
YCA  ZCA  CFID/ XCF 
YCF  ZCF  
CSID/ XCS 
YCS  ZCS  CTID/ XCT 
YCT  ZCT 
(1)  (2)  (3)  (4)  (5)  (6)  (7)  (8)  (9)  (10) 

SECOND  DTPG_ID  SX  SY  SZ  
COORD  CID  CAID/ XCA 
YCA  ZCA  CFID/ XCF 
YCF  ZCF  
CSID/ XCS 
YCS  ZCS  CTID/ XCT 
YCT  ZCT 
Example 1
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DTPG  1  PSHELL  1  9  23  
3.0  60.0  Yes  5.0  Norm  both  
PATRN  50  0.0  25.0  0.0  0.0  1.0  0.0  
PATRN2  3  1.0  0.0  0.0  
BOUNDS  1.0  1.0 
Example 2
(1)  (2)  (3)  (4)  (5)  (6)  (7)  (8)  (9)  (10) 

DTPG  1  DVGRID  1  
5.0  75.0  YES  
BOUNDS  0.0  1.0 
Definitions
Field  Contents  SI Unit Example 

ID  Each
DTPG card must have a unique ID. No default (Integer > 0) 

TYPE  Indicate whether
DTPG card is defined for PSHELL, PCOMP, DVGRID, SET or STACK (Laminate). No default 

PID#/SID#/DVID  If TYPE
is PSHELL or PCOMP, then this
entry is a Property identification number. Use ALL if it applies to all properties of type PTYPE
in the model. Numerous PIDs may be given. If TYPE is DVGRID, this entry is the Design Variable number for a set of DVGRIDs. Only one DVID may be given. If TYPE is SET, this entry is a SET identification number referring to a set of elements. If TYPE is STACK, this entry is a STACK (Laminate) identification number. Numerous STACK ID's may be provided. Default = ALL (Integer > 0, blank or ALL) 

MW  Bead minimum width. This
parameter controls the width of the beads in the model [recommended
value between 1.5 and 2.5 times the average element width]. 1 No default (Real > 0.0) 

ANG  Draw angle in degrees.
This parameter controls the angle of the sides of the beads
(recommended value between 60 and 75 degrees). 1 No default (1.0 < Real < 89.0) 

BF  Buffer zone. This
parameter will establish a buffer zone between elements in the
design domain and elements outside the design domain. 2


HGT  Draw height. This
parameter sets the maximum height of the beads to be drawn. This
field is only valid if TYPE is
PSHELL or PCOMP. No default (Real > 0.0) 

norm/XD,YD,ZD  Draw direction. If
norm/XD field is 'norm',
the shape variables will be created in the normal directions of the
elements. If all the fields are real, the shape variable will be
created in the direction specified by the xyz vector defined by the
three fields. The X, Y, and Z values are in the global coordinate
system. This field is only valid if TYPE is
PSHELL or PCOMP. Default = NORM (NORM in norm/XD field or Real in all three fields) 

SKIP  Boundary skip. This
parameter tells OptiStruct to leave
certain nodes out of the design domain.


MAXW  Indicates that maximum bead width control is active.  
MAXWTH  Maximum width of beads.
This parameter can be used to prevent the formation of large beads.
It should be at least twice the value of the minimum bead width
(MW). No default (Real > 0.0) 

MINHGT  Minimum height ratio to be
considered as bead. Only the beads with height greater than
MINHGT*HGT would be counted in maximum width constraint. Default = 0.5 (Real ≥ 0.0) 

ZEROB  Indicates whether the
width control is applied to the beads with zero height.


PATRN  Indicates that variable pattern grouping is active. Indicates that information about the pattern group will follow.  
TYP  Type of variable grouping
pattern. Required if any symmetry or variable pattern grouping is
desired. If zero or blank, anchor node, first vector, and second
vector definitions are ignored. If less than 20, second vector
definition is ignored. 4 Default = 0 (Integer ≥ 0) 

AID/XA,YA,ZA  Variable grouping pattern
anchor point. These fields define a point that determines how grids
are grouped into variables. 3 The X, Y, and Z values are in the
global coordinate system. You may put a grid ID in the
AID/XA field to define the
anchor point. Default = origin (Real in all three fields or Integer in AID/XA field) 

FID/XF,YF,ZF  Direction of first vector
for variable pattern grouping. These fields define a xyz vector
which determines how grids are grouped into variables. 3 The X, Y, and Z values are in the
global coordinate system. You may put a grid ID in the
FID/XF field to define the
first vector. This vector goes from the anchor point to this grid.
If all fields are blank and the TYP field is not
blank or zero, OptiStruct gives an
error. No default 

PATRN2  Indicates variable pattern grouping continuation card. This card is only required when a second vector is needed to define the pattern grouping.  
UCYC  Number of cyclical
repetitions for cyclical symmetry. This field defines the number of
radial "wedges" for cyclical symmetry. The angle of each wedge is
computed as 360.0/UCYC. 4 Default = 0 (Integer ≥ 0 or blank) 

SID/XS,YS,ZS  Direction used to
determine second vector for variable pattern grouping. These fields
define a xyz vector which, when combined with the first vector, form
a plane. The second vector is calculated to lie in that plane and is
perpendicular to the first vector. The second vector is sometimes
required to determine how grids are grouped into variables. 3 The X, Y, and Z values are in the
global coordinate system. You may put a grid ID in the
SID/XS field to define the
second vector. This vector goes from the anchor point to this grid.
If all fields are blank and the TYP field
contains a value of 20 or higher, OptiStruct gives an error. No default 

BOUNDS  Indicates that information on upper and lower limits and the initial value for grid movement are to follow.  
LB  Lower bound on variables
controlling grid movement. This sets the lower bound on grid
movement equal to
LB*HGT. Default = 0.0 (Real < UB) 

UB  Upper bound on variables
controlling grid movement. This sets the upper bound on grid
movement equal to
UB*HGT. Default = 1.0 (Real > LB) 

INIT  The initial value of the
variables controlling grid movement. This sets the initial value on
grid movement equal to
INIT*HGT. Default = LB + factor*(UBLB), if LB > 0.0 and UB > 0.0 Default = UB  factor*(UBLB), if LB < 0.0 and UB < 0.0 Default = factor*max(abs(LB),UB), if LB < 0.0 and UB > 0.0 where:


DDVAL  ID of
DDVAL entry that provides a set of discrete
values. (Blank or Integer > 0; Default = blank for continuous design variables) 

AUTOBEAD  Indicates that AUTOBEAD of OSSmooth is used to interpret the results as one or two level beads.  
LAYER  Number of layers.
(Integer) 

REMESH  Element size for
remeshing.
(Real ≥ 0.0) 

MAIN  Indicates that this design variable may be used as a main pattern for pattern repetition.  
COORD  Indicates information regarding the coordinate system for pattern repetition is to follow. This is required if either MAIN or SECOND flags are present.  
CID  Coordinate system ID for a
rectangular coordinate system that may be used as the pattern
repetition coordinate system. 6 Default = 0 (Integer ≥ 0) 

CAID/XCA, YCA, ZCA  Anchor point for pattern
repetition coordinate system. The point may be defined by entering a
grid ID in the CAID field or by entering X, Y,
and Z coordinates in the XCA,
YCA, and ZCA fields. These
coordinates will be in the basic coordinate system. 6 No default (Real in all three fields or Integer in the first field) 

CFID/XCF, YCF, ZCF  First point for pattern
repetition coordinate system. The point may be defined by entering a
grid ID in the CFID field or by entering X, Y,
and Z coordinates in the XCF,
YCF, and ZCF fields. These
coordinates will be in the basic coordinate system. 6 No default (Real in all three fields or Integer in the first field) 

CSID/XCS, YCS, ZCS  Second point for pattern
repetition coordinate system. The point may be defined by entering a
grid ID in the CSID field or by entering X, Y,
and Z coordinates in the XCS,
YCS, and ZCS fields. These
coordinates will be in the basic coordinate system. 6 No default (Real in all three fields or Integer in the first field) 

CTID/XCT, YCT, ZCT  Third point for pattern
repetition coordinate system. The point may be defined by entering a
grid ID in the CTID field or by entering X, Y,
and Z coordinates in the XCT,
YCT, and ZCT fields. These
coordinates will be in the basic coordinate system. 6 No default (Real in all three fields or Integer in the first field) 

SECOND  Indicates that this design variable is secondary to the main pattern definition referenced by the following DTPG_ID entry. 6  
DTPG_ID  DTPG
identification number for a main pattern definition. No default (Integer > 0) 

SX, SY, SZ  Scale factors for pattern
repetition in X, Y, and Z directions, respectively. 6 Default = 1.0 (Real > 0.0) 
Comments
 The bead minimum width and draw angles are used to determine the geometry of the shape variables. Figure 1 shows a crosssection of a single shape variable fully extended normal to the plane of the design elements. The top of the bead is flat across the circular area with a diameter equal to the minimum bead width parameter. The sides of the bead taper down at an angle equal to the draw angle parameter.
 The buffer zone is a parameter that controls how the interfaces between design and nondesign elements are treated. If active, OptiStruct will place the shape variables far enough away from the nondesign elements so that the proper bead widths and draw angles are maintained. If inactive, the boundary between the beads and nondesign elements will have an abrupt transition. Any nodes that were skipped due to the boundary skip parameter (field 10) will also have a buffer zone created around them.
 Symmetry of topography optimization can be enforced across one, two, or three planes. Defining symmetry planes for symmetric model and loading conditions is recommended because automatic variable generation may not be symmetric if it is not enforced. A symmetric mesh is not necessary, OptiStruct will create variables that are very close to identical across the plane(s) of symmetry. If the mesh is larger on one side of the plane(s) of symmetry than the other, OptiStruct will reflect variables created on the 'positive' side of the plane(s) of symmetry to the other side(s) but will not create variables on the 'negative' side(s) of the plane(s) of symmetry that do not overlap with the positive side. The positive side of the plane(s) of symmetry is the one in which the first vector, second vector, and cross product thereof are pointing toward.
 Variable pattern grouping may be defined for
a DTPG card. OptiStruct will generate
shape variables based on the type of pattern selected in field 20. For variable
grouping pattern types 1 through 14, only the first vector and anchor node need to
be defined. For variable pattern grouping types 20 or higher, the first and second
vectors need to be defined as well as the anchor node. If a grid is used to define
the first vector, the normal vector will begin at the anchor point and extend
towards the given grid (see below). Grids or xyz data may be used for either the
first vector, second vector, or anchor point and can be a mixture, (that is the
anchor point may be determined by a grid and the first vector determined by xyz data
or viceversa).One very useful feature for topography optimization in OptiStruct is the automatic generation of shape variables in simple patterns. In many cases, due to manufacturing constraints or the risk of elements being collapsed upon them during shape optimization, it is required to create shape variables in patterns that conform to the desired shape of the part. In basic topography optimization (TYP = 0), OptiStruct creates shape variables that are circular. OptiStruct contains a library of different shape variable patterns which can be accessed using the TYP parameter on the DTPG card.The second vector is calculated by taking the grid point or vector defined in fields 22, 23, and 24 and projecting it onto plane 1. If a grid point was used to define the second vector, the second vector is a vector running from the anchor node to the projected grid point. If a vector was used to define the second vector, the base of the projected vector is placed at the anchor point.
 For a list of patterns supported by OptiStruct, refer to Pattern Grouping Options.
 Pattern repetition allows similar regions of
the design domain to be linked together so as to produce similar topographical
layouts. This is facilitated through the definition of "Main" and "Secondary"
regions. A DTPG card may only contain one
MAIN or SECOND flag. Bead parameters will
not be exported for any DTPG cards containing the
SECOND flag. For both "Main" and "Secondary" regions, a
pattern repetition coordinate system is required and is described following the
COORD flag. In order to facilitate reflection, the
coordinate system may be a lefthanded or righthanded Cartesian system. The
coordinate system may be defined in one of two ways, listed here in order of
precedence:
 Four points are defined and these are utilized as follows to define the
coordinate system (this is the only way to define a lefthanded system):
 A vector from the anchor point to the first point defines the xaxis.
 The second point lies on the xy plane, indicating the positive sense of the yaxis.
 The third point indicates the positive sense of the zaxis.
 A rectangular coordinate system and an anchor point are defined. If only an anchor point is defined, it is assumed that the basic coordinate system is to be used.
Multiple "Secondary" may reference the same "Main".
Scale factors may be defined for "Secondary" regions, allowing the "Main" layout to be adjusted.
For a more detailed description, refer to Pattern Repetition in the Topography Optimization Manufacturability section of the User Guide.
 Four points are defined and these are utilized as follows to define the
coordinate system (this is the only way to define a lefthanded system):
 REMESH function uses mixed type of elements, if input mesh contains any QUAD elements; otherwise, it only uses TRIA elements.
 This card is represented as an optimization design variable in HyperMesh.