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)
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)

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)
DSHAPE	`ID`	`TYPE`
	`GRID`	`GMETH`	`ID1`	`ID2`	`ID3`	`ID4`	`ID5`	`ID6`
		`ID7`	`ID8`	etc	etc
	`BOUND`	`TOTAL`/`MESHF`	`LB`	`UB`
	`FILTER`	`FTYPE`	`RADIUS`
	`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 (VERTEXM type is currently a Beta feature).
`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. 2 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`	Classic: Field indicating whether grids are to be defined by: 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: Field indicating whether grids are to be defined by: 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`	Type of variable pattern grouping. Required if any symmetry or variable pattern grouping is desired. Only 1-plane symmetry (`TYP`=10) is currently supported. Default = 0 (0 or 10)
`AID`/`XA`, `YA`, `ZA`	Variable pattern grouping anchor point. These fields define a point that determines how grids are grouped into variables. 1 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 an xyz vector which determines how grids are grouped into variables. 1 The X, Y, and Z values 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 gives 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. 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. For Free-Shape 9.0, only consider two simple extrusion paths: 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. 6
`FTYPE`	Filtering type of nodal shape sensitivities. It indicates the method of nodal shape sensitivities smoothing. GAUSS (Default) LINEAR QUAD 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. 5 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 `PID`s 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. LOAD 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.

Comments

Classic:

For a single plane of symmetry (TYP = 10), the plane is defined normal to the first vector and is located at the anchor node.
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.
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:

Figure 1. Grid-based Free Shape Optimization
It is required to define the nodes on the surface, as well as the nodes in the interior region as design nodes.
RADIUS is sensitivities filtering radius. 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. As a consequence, the model has higher local shape changes.
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.

Figure 2.
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.
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.
When the design domain has finer mesh and more design nodes, the optimization would take more computation time.
This card is represented as an optimization design variables in HyperMesh.