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12. Shell Elements and Shell Walls - ShellElem,ShellWall

The ShellElem and ShellWall modules together provide a comprehensive set of features for computing and visualizing shell element geometry and results. Designed primarily for applications in solid mechanics, these modules also have use in other fields of engineering analysis, such as thermodynamics, in which "shell" assumptions may be made. In general, a shell element is a specialization of a three dimensional volume in which a given direction, the shell thickness, may be assumed to be small with respect to the other two directions, the shell surface.

The ShellWall module is designed to manage the thickness properties of the shell. The ShellElem module models the complete shell element by managing the surface properties of the shell explicitly and the thickness properties using a ShellWall object as an attribute object.

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12.1 Shell Elements - ShellElem

Use the ShellElem module to draw complete shell elements. Two basic representations may be selected when drawing shell elements. The simplest representation draws the shell reference surface and one or more icons which represent the thickness properties of the shell. The icons are drawn by the ShellWall attribute object and show the direction of the shell thickness, local coordinate systems and the layer thicknesses and offsets. The second representation reconstructs the three dimensional nature of the shell to some degree by drawing the top and bottom surfaces of the shell and filling the thickness of the shell edges. The laminated nature of the shell thickness properties may be color coded. The sense of the normals of the polygons used for drawing the shell bottom face are reversed so that back face culling may be used to eliminate hidden surface artifacts. If just the reference surface of the shell element is to be drawn, it is preferable to use the Face module which will draw this simple representation of a shell more efficiently.

The ShellElem module does not directly draw results quantities on shell surfaces, however it provides functions to compute coordinates and results at shell surfaces in a form which can be easily directed to an isovalue, marker or value object for drawing the results quantities in some way.

The functions associated with a ShellElem object are the following.

Instance a ShellElem object using vis_ShellElemBegin. Set attribute objects using vis_ShellElemSetObject. ShellWall and VisContext attribute objects must be set for any computational and drawing methods. The ShellWall object defines the thickness properties of the shell element.

Tapered shells may be modelled by specifying separate scale factors to be applied to the shell wall geometry at each shell corner point. These scale factors are set using vis_ShellElemSetCornerFactors. Intermediate nodes on the shell, if they exist, are given scale factors which linearly vary between the corner points. Use vis_ShellElemDirCos to compute the local coordinate system direction cosine matrix at the shell centroid or shell nodes. Use vis_ShellElemCoords to compute the coordinates of the shell nodes at a shell wall point.

A complete shell element is drawn using vis_ShellElemCurv. If the shell topology has been set to VIS_SHAPELINE by vis_ShellElemSetTopology, then only a single shell wall is drawn. If the shell shape is VIS_SHAPETRI or VIS_SHAPEQUAD then a specified number of shell walls and the shell reference surface or top and bottom shell surfaces are drawn. Shells may be drawn with up to 13 by 13 nodes along the surface of the shell. Axisymmetric shells may be drawn by computing a series of "nodes" (less than or equal to 13) which approximate the curved shell in space.

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12.2 Attribute Objects

A ShellElem object uses ShellWall, DrawFun, VisContext, ColorMap and TransMap objects to define attributes to generate a shell element visualization entity. The ShellWall object is required for any drawing or computation functions. The DrawFun and VisContext objects are required for any drawing functions. The ColorMap and TransMap are optional. A ShellElem object uses the following VisContext components.

ElemAxes
Element local coordinate system axes flags
ElemLoc
Element locations at which element coordinate systems and shell wall icons are drawn.
ElemRep
Element representation. VIS_ELEMREP_SOLID draws the top and bottom surfaces of the shell element and fills the shell thickness along the edges of the shell. The coloring of the shell thickness fill depends upon the SHELLELEM_WALL parameter set using vis_ShellElemSetParami. If enabled, the layered nature of a shell through the thickness along the shell edges may be represented. In this case the color settings of the ShellWall attribute object are used to determine coloring of the shell thickness fill. if disabled, the shell thickness is filled using the specified Color. The element coordinate system axes are drawn. Any other element representation, such as VIS_ELEMREP_SEMI draws the shell reference surface as well as element coordinate system axes and shell wall icons at the specified element locations. The representation of the shell wall icons and shell wall layers is determined by the ShellWall attribute object.
Color
Color of reference surface or top surfaces and possibly the filled shell thickness. If the SHELLELEM_WALL parameter is set then the color of the filled shell thickness is determined by by the color settings of the ShellWall attribute object.
MinorColor
Color of bottom surface.
Edge
Edge flag, the edges of the shell surfaces are drawn. If the SHELLELEM_WALL parameter is set then the boundaries between shell layers are drawn.
Fill
Fill flag, the surfaces of the shell are drawn and the shell thickness is filled.
LineWidth
Line width of edges
AColor
Color of edges.
MinorLineWidth
Line width of element axes.
Refinement
Level of refinement
Shade
Flag to apply light source shading
Shrink
Shrink factor for shell surface directions.
Size
Length of coordinate system axes.
Trans
Surface transparency
XColor
Color of coordinate system x axes
YColor
Color of coordinate system y axes
ZColor
Color of coordinate system z axes
The result of drawing a curved triangular shell element with 4 layers is illustrated in Figure 11-1a. The ElemRep is set to VIS_ELEMREP_SEMI and the ElemLoc is set to VIS_ELEMLOC_CENTROID. The reference surface and shell wall icon of the shell element are drawn. Figure 11-1b illustrates drawing the same shell element with the ElemRep is set to VIS_ELEMREP_SOLID and the SHELLELEM_WALL parameter has been enabled using vis_ShellElemSetParami. The top and bottom surfaces of the shell as well as the shell wall layers along the edges of the shell element have been drawn. The shell wall layers have been color coded to the shell wall layer id.


Figure 11-1a, Draw Shell Wall and Reference Surface of Shell Element

Figure 11-1b, Draw Tapered Triangular Shell Element with Layers
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12.3 Function Descriptions

The currently available ShellElem functions are described in detail in this section.

Table of Contents , ShellElem

NAME

*vis_ShellElemBegin - create an instance of an ShellElem object

C SPECIFICATION

vis_ShellElem *vis_ShellElemBegin ()

ARGUMENTS

None

FUNCTION RETURN VALUE

The function returns a pointer to the newly created ShellElem object. If the object creation fails, NULL is returned.

DESCRIPTION

Create an instance of an ShellElem object. Memory is allocated for the object private data and the pointer to the data is returned. By default all attribute object pointers are NULL.

Destroy an instance of a ShellElem object using 

     void vis_ShellElemEnd (vis_ShellElem *shellelem)

Return the current value of a ShellElem object error flag using 

     Vint vis_ShellElemError (vis_ShellElem *shellelem)

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NAME

vis_ShellElemCoords - compute shell coordinates

C SPECIFICATION

void vis_ShellElemCoords (vis_ShellElem *shellelem,
                          Vint id,
                          Vint reflectflag,
                          Vfloat x[][3],
                          Vint vflag, Vfloat v[][3],
                          Vfloat xp[][3])

INPUT ARGUMENTS

shellelem    Pointer to ShellElem object.
id           Shell wall point id.
reflectflag  Reverse sense of output coordinates in array xp.
             =VIS_OFF      Do no reverse sense.
             =VIS_ON       Reverse sense.
x            Array of point locations defining shell surface.
vflag        User supplied shell normal flag
             =VIS_NODATA             No normals provided
             =VIS_VERTEXDATA         Vertex normals are provided
v            Array of user supplied shell normals

OUTPUT ARGUMENTS

xp           Array of point locations of shell at shell wall point id.

DESCRIPTION

Compute the coordinates of a shell surface passing through the shell wall point specified by id. If normals, v, are not provided the thickness direction is assumed to be normal to the shell reference surface specified by x.

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NAME

vis_ShellElemCurv - draw shell element

C SPECIFICATION

void vis_ShellElemCurv (vis_ShellElem *shellelem,
                        Vfloat x[][3],
                        Vint vflag, Vfloat v[][3])

INPUT ARGUMENTS

shellelem    Pointer to ShellElem object.
x            Array of point locations defining shell reference surface.
vflag        User supplied shell z' axis normal flag
             =VIS_NODATA             No normals provided
             =VIS_VERTEXDATA         Vertex normals are provided
v            Array of user supplied vertex normals

OUTPUT ARGUMENTS

None

ERRORS

VIS_ERROR_NULLOBJECT is generated if ShellWall and VisContext attribute objects have not been set using vis_ShellElemSetObject.

DESCRIPTION

Draw a shell element with reference points, x, and optional user supplied normals v. If vertex normals are not provided, normals are calculated from the input reference geometry. Normals are used to construct the edge "faces" of the shell element. The user can input vertex normals to represent shell elements for which the vertex normals are not truely normal to the shell reference surface.

If the shell wall is to be properly drawn be sure that the wall properties have been computed or set in the ShellWall attribute object.

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NAME

vis_ShellElemDirCos - compute shell local direction cosines

C SPECIFICATION

void vis_ShellElemDirCos (vis_ShellElem *shellelem,
                          Vint centroidflag,
                          Vfloat x[][3],
                          Vfloat tm[][3][3])

INPUT ARGUMENTS

shellelem    Pointer to ShellElem object.
centroidflag Compute direction cosine matrix at shell centroid flag.
             =VIS_OFF      Return direction cosine matrices at shell nodes
             =VIS_ON       Return direction cosine matrix at shell centroid
x            Array of point locations defining shell surface.

OUTPUT ARGUMENTS

tm           Array of direction cosine matrices at the shell nodes or
             a single direction cosine matrix at the shell centroid.

DESCRIPTION

Compute the direction cosine matrices of the shell element local coordinate system. The local coordinate system is determined by the local system convention set using vis_ShellElemSetLocalSystem.

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NAME

vis_ShellElemSetCornerFactors - set shell corner node wall factors

C SPECIFICATION

void vis_ShellElemSetCornerFactors (vis_ShellElem *shellelem,
                                    Vfloat factors[])

INPUT ARGUMENTS

shellelem    Pointer to ShellElem object.
factors      Scale factors to be applied to the shell corner node walls.

OUTPUT ARGUMENTS

None

DESCRIPTION

Set shell element corner factors. By default, the corner factors are unity. In this case the shell element has a constant thickness. It is possible to model tapered shells by setting different scale factors at the corners of the shell where factors[0], factors[1], etc. are applied to the shell wall at the first, second, etc. corners of the shell element respectively. Three factors are required for a triangle, four factors for a quadrilateral shell element. The shell wall factors are assumed to vary linearly between the corner points.

These factors are used only if a ElemRep of VIS_ELEMREP_SOLID is specified in the visualization context. The default factors are unity.

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NAME

vis_ShellElemSetEdgeFlag - set edges to be drawn

C SPECIFICATION

void vis_ShellElemSetEdgeFlag (vis_ShellElem *shellelem,
                               Vint flag)

INPUT ARGUMENTS

shellelem    Pointer to ShellElem object.
flag         Element edge bit flags to indicate which shell edges are to
             have walls drawn.

OUTPUT ARGUMENTS

None

DESCRIPTION

Set shell element edge flag. The flag argument contains bit flags indicating which shell element edges are to be drawn. For example, to draw all edges of any triangular or quadrilateral shell set flag = 15; to draw the first edge only set flag = 1.

This flag is used only if a ElemRep of VIS_ELEMREP_SOLID is specified. in the visualization context. The default edge flag is 15.

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NAME

vis_ShellElemSetLocalSystem - set local coordinate system convention

C SPECIFICATION

void vis_ShellElemSetLocalSystem (vis_ShellElem *shellelem,
                                  Vint type,
                                  Vfloat vec[],
                                  Vfloat angle)

INPUT ARGUMENTS

shellelem    Pointer to ShellElem object.
type         Local system convention
             =SYS_ELEMSYS_STANDARD   Standard orientation
             =SYS_ELEMSYS_POSITION   Orient to position vector
             =SYS_ELEMSYS_GLOBALPROJECT  Orient to global axis
             =SYS_ELEMSYS_VECTOR     Orient to direction vector
             =SYS_ELEMSYS_VECTORELEMNODE Orient to nodal direction vectors
             =SYS_ELEMSYS_BISECTOR   Orient to element bisector
             =SYS_ELEMSYS_MIDPOINT   Orient to element edge midpoints
             =SYS_ELEMSYS_FIRSTEDGE  Orient to element first edge
vec          Orientation position or direction vector(s)
angle        Angle to rotate shell x',y' axes about the shell z'
             axis in degrees.

OUTPUT ARGUMENTS

None

ERRORS

VIS_ERROR_ENUM is generated if an improper type is input.

DESCRIPTION

Specify the convention to be used to construct the orientation of the shell element local x',y',z' coordinate system with respect to the shell reference surface. The z' axis is always constructed to be normal to the shell reference surface. The orientation of the x' and y' axes in the plane of the shell reference surface is determined by type. The vec array is only used if the specified type requires position or direction vectors. An additional rotation of the x',y' axes about the z' axis can be specified with angle. By default the local system convention is SYS_ELEMSYS_STANDARD with angle set to 0.

For a description of element coordinate systems, type, and associated orientation vector data, please see
1.4 Element Coordinate Systems

Table of Contents , ShellElem

NAME

vis_ShellElemSetObject - set pointers to attribute objects

C SPECIFICATION

void vis_ShellElemSetObject (vis_ShellElem *shellelem,
                             Vint objecttype,
                             Vobject *object)

INPUT ARGUMENTS

shellelem    Pointer to ShellElem object.
objecttype   The name of the object type to be set.
             =VIS_COLORMAP           ColorMap object
             =VGL_DRAWFUN            DrawFun object
             =VIS_SHELLWALL          ShellWall object
             =VIS_TRANSMAP           TransMap object
             =VIS_VISCONTEXT         VisContext object
object       Pointer to the object to be set.

OUTPUT ARGUMENTS

None

ERRORS

VIS_ERROR_OBJECTTYPE is generated if an improper objecttype is specified.

DESCRIPTION

Set a pointer to an attribute object. The attribute ShellWall object must be set before any shell drawing or computation functions are called.

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NAME

vis_ShellElemSetParami - set shell element display parameters

C SPECIFICATION

void vis_ShellElemSetParami (vis_ShellElem *shellelem,
                             Vint ptype,
                             Vint iparam)

INPUT ARGUMENTS

shellelem    Pointer to ShellElem object.
ptype        Type of display parameter to set
             =SHELLELEM_WALL         Draw shell wall layers
iparam       Specifies the integer value that ptype will be set to.
             =VIS_OFF                Turn parameter off
             =VIS_ON                 Turn parameter on

OUTPUT ARGUMENTS

None

ERRORS

VIS_ERROR_ENUM is generated if an improper ptype is specified.

DESCRIPTION

Set shell element display parameters. The parameter SHELLELEM_WALL draws the shell wall layers. This flag is used only if a ElemRep of VIS_ELEMREP_SOLID is specified. By default SHELLELEM_WALL is set to VIS_ON.

Table of Contents , ShellElem

NAME

vis_ShellElemSetTopology - set shell element topology

C SPECIFICATION

void vis_ShellElemSetTopology (vis_ShellElem *shellelem,
                               Vint shape,
                               Vint maxi,
                               Vint maxj)

INPUT ARGUMENTS

shellelem    Pointer to ShellElem object.
shape        Element shape parameter
             =VIS_SHAPELINE          Line
             =VIS_SHAPETRI           Triangle
             =VIS_SHAPEQUAD          Quadrilateral
maxi         The number of points along the i direction.
             If maxi = 0 then the linear
             element form of the specified shape is assumed.
maxj         The number of points along the j direction.
             If maxj = 0 and 2 <= maxi <= 4, then a Serendipity
             finite element is assumed.
             If 2 <= maxj <= 4 and 2 <= maxi <= 4, then a Lagrange
             finite element is assumed.
             For triangle shapes, set either maxj = 0 or maxj = maxi.
             If shape is VIS_SHAPELINE, then maxj is ignored.

OUTPUT ARGUMENTS

None

ERRORS

VIS_ERROR_VALUE is generated if a maxi less than zero is input. VIS_ERROR_ENUM is generated if an improper shape is input.

DESCRIPTION

Set shell element topology. All subsequent draw and compute methods such as vis_ShellElemCurv assume elements of this topology. Refinement is only applied to Serendipity and Lagrange finite element topologies. If maxi or maxj > 4 then piecewise linear interpolation is used within each element. See section VisTools, Computational Cells for a description of element topology conventions.

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12.4 Shell Wall Properties - ShellWall

Use the ShellWall module to manage, compute and draw the through-the-thickness properties of shell elements. The ShellWall module can represent a laminated shell with up to 256 layers with independent material orientations and material identifiers specified for each layer. Functions are provided to draw a simple line and point representation of the shell wall layup and/or the shell wall coordinate system and material orientation axes. Overall geometric and laminate material stiffness properties of the defined laminate may be computed.

The ShellWall module may also be used as an attribute object for a ShellElem object. In this case, shell wall geometry is drawn indirectly by calling the drawing methods of the ShellElem object.

The functions associated with a ShellWall object are the following.

Instance a ShellWall object using vis_ShellWallBegin. Once a ShellWall is instanced, define the shell wall construction type using vis_ShellWallDef. Like the BeamSect module, the ShellWall module allows three basic types of shell wall constructions to be defined; 1) built-in parameterized geometries, 2) user defined laminate geometries using points and line segments and 3) general shell wall properties such as overall thickness and eccentricity and material stiffness. If a built-in parameterized geometry such as SHELLWALL_MONOCOQUE is defined, the geometry parameters or dimensions are input using vis_ShellWallSetDimensions. User defined laminates using points and line segments, SHELLWALL_GEOMETRY, are input using vis_ShellWallSetPoint, vis_ShellWallSetLayer and vis_ShellWallSetElasProp. General shellwall properties, SHELLWALL_PROPS, are input using vis_ShellWallSetProps. A generic diagram of a layered shell wall appears below illustrating the shell wall z axis system, and layer numbering convention. Use vis_ShellWallSetParami to set display options to draw the layer material orientation axes, etc.


Figure 11-2, Diagram of Shell Wall with N Layers
The shell wall geometry, coordinate system and/or layer material orientations may be drawn using vis_ShellWallDraw. General shell wall properties and material stiffnesses may be computed using vis_ShellWallProps. The user may access computed or previously defined shell wall properties using vis_ShellWallGetProps. The function vis_ShellWallStrsStrn computes the tensor stress and strain at a point within a layer given the midsurface strains and curvatures.

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12.5 Attribute Objects

A ShellWall object uses DrawFun, VisContext, Levels and ColorMap objects to define attributes to generate a shell wall visualization entity. The DrawFun and VisContext objects are required for any drawing operations. The Levels object is required for drawing shell walls with layer color mapping active. The ColorMap object is optional. A ShellWall object uses the following VisContext components.

Color
Color of line drawn in thickness direction if not mapped to color.
Spot
Spot flag, the shell wall points are drawn.
PointSize
Point size of shell wall points.
LineWidth
Line width of thickness line
MinorLineWidth
Line width of coordinate system axes
MapColor
Map shell layer id or material id to color for drawing shell thickness. Use vis_ShellWallSetParami to toggle between color mapping to shell layer id or material id.
MinorColor
Color of shell wall points.
Scale
Scale factor for shell wall point z coordinates.
Size
Length of shell wall basic coordinate system axes. The length of layer material orientation axes is .707*Size.
XColor
Color of coordinate system x axes
YColor
Color of coordinate system y axes
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12.6 Function Descriptions

The currently available ShellWall functions are described in detail in this section.

Table of Contents , ShellWall

NAME

*vis_ShellWallBegin - create an instance of an ShellWall object

C SPECIFICATION

vis_ShellWall *vis_ShellWallBegin ()

ARGUMENTS

None

FUNCTION RETURN VALUE

The function returns a pointer to the newly created ShellWall object. If the object creation fails, NULL is returned.

DESCRIPTION

Create an instance of an ShellWall object. Memory is allocated for the object private data and the pointer to the data is returned. By default all attribute object pointers are NULL.

Destroy an instance of a ShellWall object using 

     void vis_ShellWallEnd (vis_ShellWall *shellwall)

Return the current value of a ShellWall object error flag using 

     Vint vis_ShellWallError (vis_ShellWall *shellwall)

Table of Contents , ShellWall

NAME

vis_ShellWallCoords - compute coordinates on shell wall

C SPECIFICATION

void vis_ShellWallCoords (vis_ShellWall *shellwall,
                          Vint id,
                          Vfloat x[][3],
                          Vfloat v[][3],
                          Vfloat xp[][3])

INPUT ARGUMENTS

shellwall    Pointer to ShellWall object.
id           Shell wall point id.
x            Location of origin of shell wall z axis.
v            Normal vector in direction of shell wall z axis in space.

OUTPUT ARGUMENTS

xp           Location of shell wall point id.

ERRORS

VIS_ERROR_VALUE is generated if an improper id is input.

DESCRIPTION

Compute the coordinates of a shell wall point, id, given a position, x, and orientation, v, of the shell wall z axis in space. If the orientation vector is not normalized to unity, the shell wall will be correspondingly scaled in space.

Table of Contents , ShellWall

NAME

vis_ShellWallDef - define shell wall type

C SPECIFICATION

void vis_ShellWallDef (vis_ShellWall *shellwall,
                       Vint type)

INPUT ARGUMENTS

shellwall    Pointer to ShellWall object.
type         Shell wall type
             =SHELLWALL_GEOMETRY     Laminated wall
             =SHELLWALL_LAMINATE     Laminated wall
             =SHELLWALL_MONOCOQUE    Single layer wall
             =SHELLWALL_PSHELL       NASTRAN PSHELL bulk data specification
             =SHELLWALL_PROPS        Generalized wall properties

OUTPUT ARGUMENTS

None

ERRORS

VIS_ERROR_ENUM is generated if an improper type is specified.

DESCRIPTION

Define the type of shell wall construction to be represented. The types SHELLWALL_GEOMETRY and SHELLWALL_LAMINATE are essentially equivalent, they provide two different ways to specify a laminated shell wall construction.

If type is input as SHELLWALL_GEOMETRY, then the user specifies a layered shell by defining point locations, layers and material properties using vis_ShellWallSetPoint, vis_ShellWallSetLayer and vis_ShellWallSetElasProp respectively.

If type is SHELLWALL_LAMINATE the user must enter the shell wall dimensions and material identifiers using vis_ShellWallSetLaminate and material properties using vis_ShellWallSetElasProp.

If type is SHELLWALL_MONOCOQUE or SHELLWALL_PSHELL the user must enter the shell wall dimensions and material identifiers using vis_ShellWallSetDimensions and material properties using vis_ShellWallSetElasProp.

If type is SHELLWALL_PROPS, the user must enter the overall thickness, eccentricity and material stiffness matrices explicitly using vis_ShellWallSetProps.

Inquire of defined type as an output argument using 

     void vis_ShellWallInq (vis_ShellWall *shellwall,
                            Vint *type)

Table of Contents , ShellWall

NAME

vis_ShellWallDraw - draw shell wall icon

C SPECIFICATION

void vis_ShellWallDraw (vis_ShellWall *shellwall,
                        Vfloat xs[3],
                        Vfloat tm[3][3])

INPUT ARGUMENTS

shellwall    Pointer to ShellWall object.
xs           Location of shell wall thickness coordinate z = 0.
tm           Orientation of shell wall basic coordinate system.

OUTPUT ARGUMENTS

None

DESCRIPTION

Draw a shell wall icon at xs with orientation tm. The icon consists of lines and points which represent the shell wall geometry and a series of coordinate axes which represent the basic shell wall coordinate system and the orientation of the material properties in each layer.

If shell wall geometry has been defined then points are drawn at the end points of the shell layers and lines are drawn connecting the layer end points. The layer lines may be color mapped to the layer id. In addition, if the appropriate display parameters have been set using vis_ShellWallSetParami, axes are drawn to represent the basic shell wall coordinate system and/or material orientation at each layer.

If only shell wall geometry is to be drawn (no coordinate axes), then only the z' orientation need appear in the tm matrix, ie. the x,y,z coordinates of a unit vector in the z' direction tm[2][0], tm[2][1], tm[2][2].

Table of Contents , ShellWall

NAME

vis_ShellWallGetNum - get number of points and layers

C SPECIFICATION

void vis_ShellWallGetNum (vis_ShellWall *shellwall,
                          Vint *npoints,
                          Vint *nlayers)

INPUT ARGUMENTS

shellwall    Pointer to ShellWall object.

OUTPUT ARGUMENTS

npoints      Number of points defined
nlayers      Number of layers defined

DESCRIPTION

Return the number of shell wall geometry points and layers defined. The points and layers may have been explicitly specified using vis_ShellWallSetPoint and vis_ShellWallSetLayer or implicitly defined as a built-in wall geometry using vis_ShellWallSetDimensions. Information about individual points and layers may be returned using vis_ShellWallGetPoint and vis_ShellWallGetLayer.

Table of Contents , ShellWall

NAME

vis_ShellWallProps - compute shell wall properties

C SPECIFICATION

void vis_ShellWallProps (vis_ShellWall *shellwall)

INPUT ARGUMENTS

shellwall    Pointer to ShellWall object.

OUTPUT ARGUMENTS

None

ERRORS

VIS_ERROR_OPERATION is generated if no shellwall geometry has been defined. VIS_ERROR_OPERATION is generated if no material properties have been defined. VIS_ERROR_VALUE is generated if material properties are undefined for a particular layer.

DESCRIPTION

Compute the geometric and material stiffness properties of the shell wall. The computed properties will replace any previously computed properties. The geometric properties consist of total thickness and offset to shellwall midsurface. Material stiffness properties consist of the shell wall extensional, coupling, bending and transverse shear stiffness matrices. Material stiffness properties are only computed if material properties have been defined using vis_ShellWallSetElasProp. Use vis_ShellWallGetProps to return the computed shell wall properties. The shell wall properties may be explicitly set using vis_ShellWallSetProps.

Table of Contents , ShellWall

NAME

vis_ShellWallSetDimensions - set dimensions of built-in geometries

C SPECIFICATION

void vis_ShellWallSetDimensions (vis_ShellWall *shellwall,
                                 Vfloat dimes[],
                                 Vfloat phis[],
                                 Vint mids[])

void vis_ShellWallSetDimensionsdv (vis_ShellWall *shellwall,
                                   Vdouble dimes[],
                                   Vdouble phis[],
                                   Vint mids[])

INPUT ARGUMENTS

shellwall    Pointer to ShellWall object.
dimes        Dimensions of wall.
phis         Material orientation angles in degrees
mids         Material property ids.

OUTPUT ARGUMENTS

None

ERRORS

VIS_ERROR_OPERATION is generated if the shell type as defined by vis_ShellWallDef is not SHELLWALL_MONOCOQUE or SHELLWALL_PSHELL.

DESCRIPTION

Set dimensions and material orientation angles and ids for a built-in shell wall type. The number and type of dimensions required are section dependent as defined by vis_ShellWallDef. The dimensions and material identifiers required by the SHELLWALL_PSHELL type are as defined by the NASTRAN PSHELL bulk data specification. 
             MONOCOQUE  PSHELL
 dimes[0] =  t          t
 dimes[1] =             12I/t**3
 dimes[2] =             ts/t

 phis[0]  =  phi        phi

 mids[0]  =  mid        mid1
 mids[1]  =             mid2
 mids[2]  =             mid3
 mids[3]  =             mid4

Table of Contents , ShellWall

NAME

vis_ShellWallSetLaminate - set laminate properties

C SPECIFICATION

void vis_ShellWallSetLaminate (vis_ShellWall *shellwall,
                               Vfloat ecc,
                               Vint nlayers,
                               Vfloat thks[],
                               Vfloat phis[],
                               Vint mids[])

void vis_ShellWallSetLaminatedv (vis_ShellWall *shellwall,
                                 Vdouble ecc,
                                 Vint nlayers,
                                 Vdouble thks[],
                                 Vdouble phis[],
                                 Vint mids[])

INPUT ARGUMENTS

shellwall    Pointer to ShellWall object.
ecc          Offset of shell midsurface from shell reference surface
nlayers      Number of layers, nlayers > 0
thks         Layer thicknesses
phis         Material orientation angles in degrees
mids         Material property ids.

OUTPUT ARGUMENTS

None

ERRORS

VIS_ERROR_OPERATION is generated if the shell type as defined by vis_ShellWallDef is not SHELLWALL_LAMINATE. VIS_ERROR_VALUE is generated if an improper nlayers is specified.

DESCRIPTION

Set laminate properties.

Table of Contents , ShellWall

NAME

vis_ShellWallSetElasProp - set elastic material properties

C SPECIFICATION

void vis_ShellWallSetElasProp (vis_ShellWall *shellwall,
                               Vint id,
                               Vint type,
                               Vfloat material[])

void vis_ShellWallSetElasPropdv (vis_ShellWall *shellwall,
                                 Vint id,
                                 Vint type,
                                 Vdouble material[])

INPUT ARGUMENTS

shellwall    Pointer to ShellWall object.
id           Material id, 0 < id.
type         The material property type
             =SYS_MAT_ISOTROPIC      Isotropic
             =SYS_MAT_LAMINA         Lamina
             =SYS_MAT_ORTHOTROPIC    Orthotropic
             =SYS_MAT_ANISOTROPIC    Anisotropic
material     Array of material properties

OUTPUT ARGUMENTS

None

ERRORS

VIS_ERROR_VALUE is generated if an improper material id is specified. VIS_ERROR_ENUM is generated if an improper material type is specified.

DESCRIPTION

Set material properties associated with a material identifier, the material identifier, id may be any positive integer. The material properties are input in array material in the order specified for a particular type. For isotropic materials input 2 values (E,Nu). For lamina materials input 6 values (Ex,Ey,Nuxy,Gxy,Gyz,Gxz). For orthotropic materials input 9 values (Ex,Ey,Ez,Nuxy,Nuyz,Nuxz,Gxy,Gyz,Gxz). For anisotropic materials input 21 values, the lower triangle of the 6x6 material D-matrix by rows.

Table of Contents , ShellWall

NAME

vis_ShellWallSetLayer - set layer point connectivity, etc.

C SPECIFICATION

void vis_ShellWallSetLayer (vis_ShellWall *shellwall,
                            Vint id,
                            Vint ix[],
                            Vfloat phi,
                            Vint mid)

void vis_ShellWallSetLayerdv (vis_ShellWall *shellwall,
                              Vint id,
                              Vint ix[],
                              Vdouble phi,
                              Vint mid)

INPUT ARGUMENTS

shellwall    Pointer to ShellWall object.
id           Layer id, 1 <= id <= 256
ix           End point connectivity of layer
phi          Material orientation angle in degrees
mid          Material property id.

OUTPUT ARGUMENTS

None

ERRORS

VIS_ERROR_OPERATION is generated if the shell type as defined by vis_ShellWallDef is not SHELLWALL_GEOMETRY. VIS_ERROR_VALUE is generated if an improper id is input.

DESCRIPTION

Set the end point connectivity, material orientation angle and material id or layer id. The end point connectivity consists of two point ids, the points defining the bottom and top of the layer respectively. The layer ids should be consecutively numbered from the bottom to the top of the shell wall.

Inquire of layer geometry for a given layer id as output arguments using 

     void vis_ShellWallGetLayer (vis_ShellWall *shellwall,
                                 Vint id,
                                 Vint ix[],
                                 Vfloat *phi,
                                 Vint *mid)

     void vis_ShellWallGetLayerdv (vis_ShellWall *shellwall,
                                   Vint id,
                                   Vint ix[],
                                   Vdouble *phi,
                                   Vint *mid)

Table of Contents , ShellWall

NAME

vis_ShellWallSetObject - set pointers to attribute objects

C SPECIFICATION

void vis_ShellWallSetObject (vis_ShellWall *shellwall,
                             Vint objecttype,
                             Vobject *object)

INPUT ARGUMENTS

shellwall    Pointer to ShellWall object.
objecttype   The name of the object type to be set.
             =VIS_COLORMAP           ColorMap object
             =VGL_DRAWFUN            DrawFun object
             =VIS_LEVELS             Levels object
             =VIS_VISCONTEXT         VisContext object
object       Pointer to the object to be set.

OUTPUT ARGUMENTS

None

ERRORS

VIS_ERROR_OBJECTTYPE is generated if an improper objecttype is specified.

DESCRIPTION

Set a pointer to an attribute object.

Table of Contents , ShellWall

NAME

vis_ShellWallSetParami - set shell wall display parameters

C SPECIFICATION

void vis_ShellWallSetParami (vis_ShellWall *shellwall,
                             Vint ptype,
                             Vint iparam)

INPUT ARGUMENTS

shellwall    Pointer to ShellWall object.
ptype        Type of display parameter to set
             =SHELLWALL_AXESBASIC     Draw basic local coordinate system
             =SHELLWALL_AXESLAYER     Draw layer material orientation axes
             =SHELLWALL_MAPMATERIALID Map color to material id
iparam       Specifies the integer value that ptype will be set to.
             =VIS_OFF                Turn parameter off
             =VIS_ON                 Turn parameter on

OUTPUT ARGUMENTS

None

ERRORS

VIS_ERROR_ENUM is generated if an improper ptype is specified.

DESCRIPTION

Set shell wall display parameters. The parameter SHELLWALL_AXESBASIC draws the shell wall basic coordinate system x and y axes. By default SHELLWALL_AXESBASIC is set to VIS_OFF.

The parameter SHELLWALL_AXESLAYER draws the shell wall layer material orientation x and y axes. By default SHELLWALL_AXESLAYER is set to VIS_ON.

The parameter SHELLWALL_MAPMATERIALID maps layer material id to color rather than the default layer id if MapColor is enabled in the VisContext attribute object. By default SHELLWALL_MAPMATERIALID is set to VIS_OFF.

Table of Contents , ShellWall

NAME

vis_ShellWallSetPoint - set location of point on shell wall

C SPECIFICATION

void vis_ShellWallSetPoint (vis_ShellWall *shellwall,
                            Vint id,
                            Vfloat z)

void vis_ShellWallSetPointdv (vis_ShellWall *shellwall,
                              Vint id,
                              Vdouble z)

INPUT ARGUMENTS

shellwall    Pointer to ShellWall object.
id           Point id, 1 <= id <= 256
z            Z coordinate of point on shell wall

OUTPUT ARGUMENTS

None

ERRORS

VIS_ERROR_OPERATION is generated if the shell type as defined by vis_ShellWallDef is not SHELLWALL_GEOMETRY. VIS_ERROR_VALUE is generated if an improper id is input.

DESCRIPTION

Set the z coordinate of a point, id, on the shell wall. Use vis_ShellWallSetLayer to define layer geometry using points.

Inquire of point coordinate for a given point id as an output argument using 

     void vis_ShellWallGetPoint (vis_ShellWall *shellwall,
                                 Vint id,
                                 Vfloat *z)

     void vis_ShellWallGetPointdv (vis_ShellWall *shellwall,
                                   Vint id,
                                   Vdouble *z)

Table of Contents , ShellWall

NAME

vis_ShellWallSetProps - set general shell wall properties

C SPECIFICATION

void vis_ShellWallSetProps (vis_ShellWall *shellwall,
                            Vfloat props[2],
                            Vfloat abdmat[21],
                            Vfloat qmat[3])

void vis_ShellWallSetPropsdv (vis_ShellWall *shellwall,
                              Vdouble props[2],
                              Vdouble abdmat[21],
                              Vdouble qmat[3])

INPUT ARGUMENTS

shellwall    Pointer to ShellWall object.

OUTPUT ARGUMENTS

props        Overall shell wall thickness and distance of midsurface from
             reference surface (z = 0.)
abdmat       Lower triangle of extensional-bending stiffness matrix
qmat         Lower triangle of transverse shear material stiffness matrix

ERRORS

VIS_ERROR_OPERATION is generated if the shell type as defined by vis_ShellWallDef is not SHELLWALL_PROPS.

DESCRIPTION

Set the general shell wall properties. The overall thickness and eccenticity are set. The wall properties must appear as follows in the input props vector. 

props[0] - Thickness, T
props[1] - Eccentricity of midsurface from origin along z axis, Ez
The shell wall properties may be accessed for any shell type. Inquire of shell wall properties as output arguments using 
     void vis_ShellWallGetProps (vis_ShellWall *shellwall,
                                 Vfloat props[2],
                                 Vfloat abdmat[6],
                                 Vfloat qmat[3])

     void vis_ShellWallGetPropsdv (vis_ShellWall *shellwall,
                                   Vdouble props[2],
                                   Vdouble abdmat[6],
                                   Vdouble qmat[3])

Table of Contents , ShellWall

NAME

vis_ShellWallStrsStrn - compute shell stress and strain

C SPECIFICATION

void vis_ShellWallStrsStrn (vis_ShellWall *shellwall,
                            Vint id,
                            Vint pos,
                            Vfloat eks[8],
                            Vfloat strs[6],
                            Vfloat strn[6]);

INPUT ARGUMENTS

shellwall    Pointer to ShellWall object.
id           Shell wall layer id.
pos          Shell wall layer position
             =VIS_BOTTOM             Layer bottom
             =VIS_CENTER             Layer center
             =VIS_TOP                Layer top
eks          Strains and curvatures

OUTPUT ARGUMENTS

strs         Stress tensor
strn         Strain tensor

ERRORS

VIS_ERROR_OPERATION is generated if no shellwall geometry has been defined. VIS_ERROR_OPERATION is generated if no material properties have been defined. VIS_ERROR_VALUE is generated if material properties are undefined for a particular layer or an improper layer id is specified. VIS_ERROR_ENUM is generated if an improper layer position is specified.

DESCRIPTION

Compute the full stress, strs and strain, strn tensor at position, pos, in shell wall layer id given the strains and curvatures, eks. The stress and strain components are ordered (xx,yy,zz,xy,yz,zx) The components of eks are ordered (exx,eyy,exy,kxx,kyy,kxy,eyz,ezx).

Note that if the right-hand rotations about the x,y,z axes are denoted by rx,ry,rz, then the curvatures, kxx,kyy,kxy, are given by: 

   kxx =  ry,x
   kyy = -rx,y
   kxy =  ry,y - rx,x
Given this definition, the components of curvature, (kxx,kyy,kxy), do not transform as a tensor.

The transverse shear stresses, assuming that no tangential tractions are applied to the shell surfaces, must be zero at the shell surfaces and peak at the center. The transverse shear stresses are therefore adjusted by the following factor: 

     1.5*(1-r*r)
where r is the normal coordinate which varies in the interval (-1.,1.) from the bottom to the top surface.