# DSHAPE

Bulk Data Entry Defines parameters for classic and grid-based free-shape design variables.

## Format 1 (Classic)

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
DSHAPE ID TYPE
PERT DTYPE MVFACTOR NSMOOTH MXSHRK MXGROW SMETHOD NTRANS
GRID GMETH GSETID1/

GID1

GID2/

GSETID2

GID3/

GSETID3

GID4/

GSETID4

GID5/

GSETID5

GID6/

GSETID6

GID7/

GSETID7

GID8/

GSETID8

etc etc
PATRN TYP AID/

XA

YA ZA FID/

XF

YF ZF
DRAW DTYP DAID/

XDA

YDA ZDA DFID/

XDF

YDF ZDF
DRAFT
EXTR ECID XE YE ZE
GRIDCON GCMETH GCSETID1 /

GDID1

CTYPE1 CID1 X1 Y1 Z1
GCMETH GCSETID2 /

GDID2

CTYPE2 CID2 X2 Y2 Z2
etc etc
SDCON SDCID1 XL1 XU1 YL1 YU1 ZL1 ZU1
SDCID2 XL2 XU2 YL2 YU2 ZL2 ZU2
etc etc
BMESH BMID
FSSPLIT SPLIT

## Format 2 (Grid-based, Vertex Morphing)

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
DSHAPE ID TYPE
GRID GMETH ID1 ID2 ID3 ID4 ID5 ID6
ID7 ID8 etc etc
PATRN TYP AID/XA YA ZA FID/XF YF ZF
SID/XS YS ZS
BOUND TOTAL/MESHF LB UB
BOUNDARY BTYPE/SETID   SKIP
GRIDCON GCMETH GCSETID1 CTYPE2 CID1 X1 Y1 Z1
etc GCMETH GCSETID2 CTYPE2 CID2 X2 Y2 Z2
etc etc
BMESH BMID
SMOOTH METHOD NLAYER TRANS

## Definitions

Field Contents SI Unit Example
ID Each DSHAPE card must have a unique ID.

No default (Integer > 0)

TYPE Free-shape optimization type.
CLASSIC (Default)
Classic free-shape optimization method.
VERTEXM
Vertex Morphing Free-Shape Optimization, method with more flexible shape changes (including normal to the shell surface). Each DSHAPE grid point has its own design variable.

PERT Indicates perturbation information is to follow.
DTYPE Direction type for the free-shape variation.
GROW
Grids cannot move inside of the initial part boundary.
SHRINK
Grids cannot move outside of the initial part boundary.
BOTH (Default)
Grids are unconstrained.

MVFACTOR Initial limit on the movement factor of the design grids. The unit of MVFACTOR is the average mesh size of meshes adjacent to grids defined after GRID.

Only the initial value of this limit can be set. The values in subsequent optimization iterations are automatically adjusted to enhance to enhance iterative stability and convergence speed; however, they will never be greater than the initial limit.

Default = 0.5 (Real > 0.0)

NSMOOTH Number of grids layers NSMOOTH.

Default = 10 (Integer)

MXSHRK Maximum shrinking distance.

No default

MXGROW Maximum growing distance.

No default

SMETHOD Mesh smoothing method.

Method 1 is faster than method 2, but method 2 is more robust in avoiding mesh distortion.

Default = 1 (1 or 2)

NTRANS Number of design grid layers in the transition zone to non-design area, where additional treatment will be applied to produce smooth transition. 1

Default = 0 (Integer ≥ 0)

GRID Indicates that a list of grid IDs or grid sets is to follow (depending on the value of the GMETH field). These grids are design variables for the free-shape optimization.
GMETH Field indicating whether grids are to be defined by.
• Classic:
ID (Default)
The following fields on this continuation line are grid point IDs.
SET
The following fields on this continuation line are grid SET ID's.
• Grid-based:
ID (Default)
The following fields on this continuation line are grid point IDs.
SET
The following fields on this continuation line are grid SET IDs.
ELEM
The following fields on this continuation line are element IDs.
PSHELL
The following fields on this continuation line are PSHELL IDs.
PCOMP
The following fields on this continuation line are PCOMP# IDs.
PSOLID
The following fields on this continuation line are PSOLID IDs.

GID# Grid identification numbers. List of grids for which this DSHAPE card is defined (only valid if GMETH field is set to ID).

No default (Integer > 0)

GSETID# Grid SET identification number. A grid set containing design grids for free-shape optimization (only valid if GMETH field is set to SET).

No default (Integer > 0)

ID# Identification numbers. List of identification numbers that depend on the value of the GMETH field in grid-based free-shape optimization.

No default (Integer > 0)

PATRN Indicates that variable pattern grouping is active. Indicates that information about the pattern group will follow.
TYP Variable pattern grouping type. Required if any symmetry or variable pattern grouping is desired. 1
0 (Default)
No pattern grouping
10
1-plane symmetry
20
2-plane symmetry
30
2-plane symmetry

1-plane symmetry is supported for both CLASSIC and VERTEXM.

2- and 3-plane symmetries are available only for VERTEXM.

(Integer)

AID/XA, YA, ZA Variable pattern grouping anchor nodes.

These fields define a point that determines how grids are grouped into variables. 1

The point may be defined by entering a grid ID in the SID field or by entering X, Y, and Z coordinates in the XS, YS, and ZS fields. These coordinates are in the global coordinate system.

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 an xyz vector which determines how grids are grouped into variables. 1

The X, Y, and Z coordinates are in the global coordinate system.

If FID is defined, it defines a vector pointing from grid AID or point (XA, YA, and ZA) to grid FID.

If XF, YF, ZF are defined, it defines a vector pointing from point (XA, YA, and ZA) to point (XA+XF,YA+YF,ZA+ZF). (XA, YA, and ZA) are coordinates of the anchor point defined by AID or XA, YA, and ZA.

If all fields are blank and the TYP field is not blank or zero, OptiStruct returns an error.

No default

SID/XS, YS, ZS Direction used to determine second vector for variable pattern grouping. 1

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. 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 returns an error.

No default

DRAW Indicates that casting constraints are being applied. Indicates that draw direction information is to follow. Only valid for design grids on solid elements.
DTYP Draw direction constraint type.
SINGLE
Indicates that a single die will be used, the die being withdrawn in the given draw direction.
Only SINGLE is available in v9.0.

DAID/XDA, YDA, ZDA Draw direction anchor point. These fields define the anchor point for draw direction of the casting. The point may be defined by entering a grid ID in the DAID field or by entering X, Y, and Z coordinates in the XDA, YDA, and ZDA fields, these coordinates will be in the basic coordinate system.

Default = origin (Real in all three fields or Integer in first field)

DFID/XDF, YDF, ZDF Direction of vector for draw direction definition. These fields define a point. The vector goes from the anchor point to this point. The point may be defined by entering a grid ID in the DFID field or by entering X, Y, and Z coordinates in the XDF, YDF, and ZDF fields, these coordinates will be in the basic coordinate system.

No default (Real in all three fields or Integer in first field)

DRAFT Draft angle in degrees. 2

Default = 0.0 (0.0 ≤ Real < 90.0)

SDCON# Indicates that side constraints are being applied.
SDCID# The ID of a coordinate system which the following XL#, XU#, YL#, YU#, ZL#, or ZU# components are resolved in.
XL#, XU#, YL#, YU#, ZL#, ZU# Side constraints defined by lower and upper bounds of coordinates, which restrict the moving space of the design grids. Any of the six fields could be blank, which means the corresponding coordinate is not constrained.
EXTR Indicates that extrusion constraints are being applied. Indicates that extrusion information is to follow. Only valid for design grids on solid elements.
ECID The ID of a coordinate system which the following X, Y, and Z components are resolved in.
Line
ECID is a rectangular system.
Circle
ECID is a cylindrical system.

Default = 0 (Integer > 0)

XE, YE, ZE When ECID is a rectangular system ID, X, Y, and Z are components of a vector under system EID, which define the extrusion path.
GRIDCON Indicates that a list of grids with associated constraints are to follow.
Note: Grids within the smoothing zone (defined by NSMOOTH) will move during Free-shape optimization to avoid mesh distortion without changing the shape of the model. You can also constrain the movement of these grids by GRIDCON even if they are not defined after GRID.

GCMETH Indicates that a list of grids is to be defined by:
ID (Default)
A list of grid IDs
SET
A single SET reference

GCSETID# Grid SET identification numbers. IDs of certain grid SETs which are constrained to move in a predefined manner.

No default (Integer > 0)

GDID# IDs of certain grids which are constrained to move in a predefined manner.

No default (Integer > 0, ID must also be present in the list following the GRID flag)

CTYPE# Constraint type applied to the grid GDID#.
FIXED
Grid cannot move due to free-shape optimization.
VECTOR
Grid is forced to move along the vector defined by the following fields.
PLANAR
Grid is forced to remain on a plane for which the following fields define the normal direction.

No default

CID# The ID of a coordinate system which the following X, Y, and Z components are resolved in.

Default = 0 (Integer ≥ 0)

X#, Y#, Z# X, Y, and Z components of a vector, which either defines the direction in which the grid GDID# is constrained to move, or the normal of a plane on which the grid GDID# is constrained to remain.

Default = 0.0 (Real)

BMESH Indicates that a BMFACE ID is to follow.
BMID The BMFACE ID which defines a list of QUADs and/or TRIAs which define a barrier that the design surface will not penetrate during shape optimization.
FSSPLIT Indicates that the design grids in the Free-Shape design space referenced by DSHAPE are split into multiple DSHAPE's, based on their normal orientation.
SPLIT Controls the splitting of the design grids for this DSHAPE entry.
YES
Design grids are split based on their normal orientation.
NO (Default)
Design grids are not split.

BOUND Indicates that shape variable bounds are to follow.
TOTAL/MESHF Character flag indicating the bound setting way.
TOTAL
The following LB and UB are total absolute values.
MESHF
The following LB and UB are relative factors of average mesh size.

No default

LB Shape design variable lower bound.

Default value = -5.0* average mesh size

When TOTAL is specified, (Blank, Real ≤ 0.0)

When MESHF is specified, (Blank, Real ≥ 0.0)

UB Shape design variable upper bound.

Default value = 5.0* average mesh size

(Blank, Real ≥ 0.0)

FILTER Indicates that nodal shape sensitivities filtering options are to follow. 3
FTYPE Filtering type of nodal shape sensitivities. It indicates the method of nodal shape sensitivities smoothing.
GAUSS (Default)
LINEAR
CUBIC

RADIUS Sensitivities filtering radius. It requires a reasonable value based on average mesh size of design domain. It is recommended that the filter radius is not too small compared to the average mesh size or too large compared to the whole design domain. 2

Default = 4* average mesh size (Real > 0.0)

BOUNDARY Indicates that the boundary information of design domain is to follow.
BTYPE Boundary handling type for shell design domain.
FREE (Default)
The boundary edge can move during optimization.
FIXED
The boundary edge is fixed.

SETID Grid SET identification number, which contains a set of non-design grids.

No default (Blank or Integer > 0)

SKIP Boundary skip. This parameter tells OptiStruct to skip certain nodes out of the design domain.
NONE
All nodes attached to elements whose PIDs are specified, will be a part of the shape variables.
BC/SPC
Any nodes which have SPC or SPC1 declarations are omitted from the design domain.
Any nodes which have FORCE, FORCE1, MOMENT, MOMENT1, or SPCD declarations are omitted from the design domain.
BOTH (Default)
Nodes with either SPC or LOAD declarations are omitted from the design domain.

SMOOTH Flag to indicate that the parameters for mesh smoothing method are to follow.
METHOD Mesh smoothing method.
1 (Default)
Laplacian based method.
2
FEA based method.

NLAYER Number of grid layers for mesh smoothing.
ALL
Indicates that the entire model is involved in mesh smoothing.

Default = 10 (Integer > 0 or ALL)

TRANS Flag to indicate a transition zone to the non-design region.
YES
There is a transition zone to a non-design region.
NO (Default)
There is no transition zone to a non-design region.

Classic:
1. The NTRANS option allows you to achieve a smooth transition between design and non-design regions. This additional smoothness; however, comes with an inherent cost of a reduction in design flexibility. NTRANS improves design smoothness across the transition zone between design and non-design regions at the expense of design flexibility.

For detailed information illustrating the working mechanism of NTRANS, refer to Define Free-shape Design Regions in the User Guide.

2. The draft angle can be specified in degrees via the DRAFT field, as illustrated in Figure 1. Geometric constraints (GRIDCON and SDCON) may not be satisfied when the draft angle is activated:
Grid based (Vertex Morphing):
1. It is required to define the nodes on the surface, as well as the nodes in the interior region as design nodes.
2. For a given design node, the solver only considers its surrounding design nodes, which the distance to this given node is within RADIUS, for sensitivities filtering. RADIUS is quite significant to the final shape design. The shape change is drastic when RADIUS is small; therfeore, the model has higher local shape changes.
3. For a given design node, its smoothed sensitivity is ( $\frac{\sum {f}_{i}g{}_{i}}{\sum {f}_{i}}$ ),
Where,
${f}_{i}$
Filtering factor at node #i
${g}_{i}$
Sensitivity at node #i
Filtering factor is calculated based on FTYPE, Figure 2 shows the filter factor curves for each FTYPE. Generally filtering factor at this given node is 1.0, since it is at the center, and the node outside RADIUS has zero filtering factor.
4. For multiple disconnected design patches, it is recommended to define separate DSHAPE for each disconnected patch; however, it is not recommended to define multiple DSHAPE cards for connected design domains.
5. LB and UB in BOUND continuation line are applied to each design variable, not the total magnitude of a design grid, that means the total magnitude may be beyond bounds.
6. When the design domain has finer mesh and more design nodes, the optimization would take more computation time.
• For 1-plane symmetry (TYP = 10):
The symmetry plane is defined normal to the first vector (FID/XF, YF, ZF) and is located at the anchor node (AID/XA, YA, ZA).
• 2-plane symmetry (TYP = 20):

The first symmetry plane (Plane 1) is defined normal to the first vector (FID/XF, YF, ZF) and is located at the anchor node, (Figure 3).

To obtain the second symmetry plane (Plane 2), the second vector is calculated by taking the vector defined in SID/XS, YS, ZS 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. The second vector is normal to plane 2, (Figure 4).

TYP = 20 is applicable only to VERTEXM.
• 3-plane symmetry (TYP = 30):

The first and second symmetry planes (Plane 1 and Plane 2) are determined as explained above.

Plane 3 is determined to be normal to both plane 1 and plane 2, (Figure 5).

TYP = 30 is applicable only to VERTEXM.
1. This card is represented as an optimization design variables in HyperMesh.