elem offset panel

Location: 2D and 3D pages

Use the Elem Offset panel to create and modify elements by offsetting from a mesh of plate or shell elements. The element normals provide directional information.

Subpanels and Inputs

The Element Offset panel contains the following subpanels and command buttons:

Before you offset plate elements, make sure that the normals of the plate elements are properly aligned.

The offset can be a negative value.

HM_Panels_bmp00113

Elements have been selected

HM_Panels_bmp00116

This illustration shows the same elements created with initial offset= set to 40.

HM_Panels_bmp00119

This illustration shows the same elements created with no biasing factor.

HM_Panels_bmp00118

The elements in this illustration were created with a negative biasing factor.

Panel Inputs

Input	Action
elems to offset selector	Select which elements you want to offset.
along geoms to follow	These entities (surfaces or elements) act as guides for the sides of the offset elements.
numbers of layers	The number of layers of elements to build along the normal direction.
Use distr thick	Select this check box to apply the distributed BL thickness ratio that you defined in the Distributed BL Thickness Ratio dialog. To access this dialog, click Set distr thick. If you clear this check box, HyperMesh will ignore the defined distributed BL thickness ratio.
initial offset	An initial offset from the surface of the plate elements along the positive normal direction.
total thickness	The total thickness of the layers of solid elements you want to create.
biasing style	Select linear or no biasing, exponential, or bellcurve
bias intensity	Enter the biasing intensity value.
elements to current comp / original comp	Specify if you want the newly created components to appear in the current component, or in the components of the shell elements.
corners style	Square corners maintain the element normals, producing sharp corners but resulting in corner elements with severe angles. Rounded corners are similar, but adjust the element thickness as the mesh nears the corner, reducing the severity of the corner elements’ angles. CFD corners are similar to rounded corners, but they do not attempt to maintain the element normals, so all of the edges of each element are adjusted to reduce the severity of their corner angles.

elem_offset__corners

The bottom/front mesh uses rounded corners; the middle mesh uses square corners;
the top mesh uses CFD corners (notice that CFD elements "lean" toward the corners).

Comments

The command function HM_COMP_TK is called to calculate each component’s thickness. This function has one argument which must be the thickness of the component. Below is an example:

*function("HM_COMP_TKvariable1)

*components(""")

*format()

*variableset(variable1,$TK)

*output()

*return()

A template that contains the HM_COMP_TK function must be specified in the user profile.

Before you offset plate elements, make sure that the normals of the plate elements are properly aligned.

The offset can be a negative value.

HM_Panels_bmp00113

Elements have been selected

elemoff1

The elements in the illustration were created with square corners.

elemoff2

This illustration shows the same elements created with rounded corners.

elemoff3

This illustration shows the same elements created with initial offset= set to 40.

Panel Inputs

Input	Action
elems to offset selector	Select which elements you want to offset.
along geoms to follow	These entities (surfaces or elements) act as guides for the sides of the offset elements.
numbers of layers	The number of layers of elements to build along the normal direction.
initial offset	An initial offset from the surface of the plate elements along the positive normal direction.
total thickness	The total thickness of the layers of solid elements you want to create.
biasing style	Select linear or no biasing, exponential, or bellcurve.
elements to current comp / original comp	Specify if you want the newly created components to appear in the current component, or in the components of the shell elements.
corners style	Square corners maintain the element normals, producing sharp corners but resulting in corner elements with severe angles. Rounded corners are similar, but adjust the element thickness as the mesh nears the corner, reducing the severity of the corner elements’ angles. CFD corners are similar to rounded corners, but they do not attempt to maintain the element normals, so all of the edges of each element are adjusted to reduce the severity of their corner angles.

elem_offset__corners

The bottom/front mesh uses rounded corners; the middle mesh uses square corners;
the top mesh uses CFD corners (notice that CFD elements "lean" toward the corners).

Comments

The command function HM_COMP_TK is called to calculate each component’s thickness. This function has one argument, which must be the thickness of the component. Below is an example:

*function("HM_COMP_TKvariable1)

*components(""")

*format()

*variableset(variable1,$TK)

*output()

*return()

A template that contains the HM_COMP_TK function must be specified in the user profile.

The order of the buttons, offset - and offset+, is reversed compared to the other panels to remind you that in most cases, offset - is the function to use. If you build a mesh on the surface of a CAD solid body, the elements will be aligned out of the object. So, when you use this tool to offset them to the midsurface of the solid, you will want them to go in the reverse of the element normals.

This function is very similar to the Translate panel, except that instead of moving all of the elements in a fixed, uniform direction, it moves each in a direction corresponding to the local normal of the mesh in the vicinity of that element. When the selected elements are moved, entities connected to them or to their nodes, such as loads, systems, equations, or other elements, move along with them.

Panel Inputs

Input	Action
elems to offset selector	Select which elements you want to offset.
along geoms to follow	These entities (surfaces or elements) act as guides for the sides of the offset elements.
distance / distance = 1/2 element T	distance = allows you to specify a fixed distance to move the elements. distance = 1/2 of element T allows you to move the elements a distance equal to half of the material thickness of the component in which each element resides.
corners style	Square corners maintain the element normals, producing sharp corners but resulting in corner elements with severe angles. Rounded corners are similar, but adjust the element thickness as the mesh nears the corner, reducing the severity of the corner elements’ angles. CFD corners are similar to rounded corners, but they do not attempt to maintain the element normals, so all of the edges of each element are adjusted to reduce the severity of their corner angles.

elem_offset__corners

The bottom/front mesh uses rounded corners; the middle mesh uses square corners;
the top mesh uses CFD corners (notice that CFD elements "lean" toward the corners).

Comments

The command function HM_COMP_TK is called to calculate each component’s thickness. This function has one argument, which must be the thickness of the component. Below is an example:

*function("HM_COMP_TKvariable1)

*components(""")

*format()

*variableset(variable1,$TK)

*output()

*return()

A template that contains the HM_COMP_TK function must be specified in the user profile.

Use the Thicken Shells subpanel to convert thin shells into solid elements by making them thicker/adding a third dimension to them. When working with shells on an outer surface, you can choose the direction to extrude them; when working with shells on a midsurface, they are automatically extruded in both positive and negative normal directions.

Panel Inputs

Input	Action
elems to offset selector	Select which elements you want to offset.
along geoms to follow	These entities (surfaces or elements) act as guides for the sides of the offset elements.
shells are on the midsurface / shells are on an outer surface	select shells are on an outer surface: the replacement shells are formed around the selected elements. shells are on the midsurface: the replacement shells are formed above or below the selected elements.
thickness =	Thickness value.
elements to current comp / original comp	Specify if you want the newly created components to appear in the current component, or in the components of the shell elements.
corners style	Square corners maintain the element normals, producing sharp corners but resulting in corner elements with severe angles. Rounded corners are similar, but adjust the element thickness as the mesh nears the corner, reducing the severity of the corner elements’ angles. CFD corners are similar to rounded corners, but they do not attempt to maintain the element normals, so all of the edges of each element are adjusted to reduce the severity of their corner angles.

elem_offset__corners

The bottom/front mesh uses rounded corners; the middle mesh uses square corners;
the top mesh uses CFD corners (notice that CFD elements "lean" toward the corners).

Comments

*components(""")

*format()

*variableset(variable1,$TK)

*output()

*return()

A template that contains the HM_COMP_TK function must be specified in the user profile.

Use the Thin Solids subpanel to create thin solid meshes. The mesh is created by first generating a 2D mesh on a selected set of faces, and then extruding this mesh to generate solid hexa or wedge elements.


Original solid geometry representing thin, bent sheet metal.		Solid meshed with 3 layers and mixed element type.

In order to create a thin solid mesh, the solid geometry must meet certain criteria:

•	The solid entity should be a bent sheet metal solid.

•	You should be able to identify both the Source (start) faces and the Destination faces.

•	Source and destination faces must be connected by side (along) faces which are almost 90 degrees to them.

•	The number of top and bottom faces do not need to match

•	Side faces do not need to be four-sided

Panel Inputs

Input

Action

thin solid mesh: solids / elems

Use this selector to pick the solid entity or elements that you wish to create a thin solid mesh from. Use the switch to choose between solids or elems.

auto detect / detect now

Auto detect is the default, and automatically determines the faces to use for the initial shell mesh.

When toggled to display the detect now button, additional fields display to allow you to manually select along surfs and destination surfs. Clicking detect now populates these collectors as if using the autodetect feature, but gives you the opportunity to add or remove faces from each collector by highlighting it and left- or right-clicking faces in the graphics area.

save src to SAVELIST

This checkbox only displays when the detection mode is set to detect now, and is active by default. When active, the detected source faces are saved in memory (and written to the command file) for easy retrieval.

Note:

They are not saved to disk as part of the model.

along surfs / source surfs

Use the toggle to switch between these two options.

•	along surfs are surfaces that define where the edges of the extruded solid elements should fall.

•	source surfs are surfaces from which the thin solid elements will be extruded.

destination: surfs

These surfaces are the target toward which the base mesh will be extruded.

number of layers:

The number of layers of elements to build along the normal direction.

element size = / elem_size/thickness

Use the toggle to switch between these two options.

•	Elem size = allows you to specify the desired element size.

thinsolid_meshed

Elem size = 2 (3 layers)

•	elem_size/thickness = determines the element size by letting you specify the ratio of size to part thickness. Since the element size is based on the part thickness, the mesh will be finer in thinner areas.

thinsolid_meshed_sizeoverthickness

Elem_size/thicnkess = 2 (3 layers)

element type =

This determines the type of elements used in the initial shell mesh from which solid elements are created.

Select quads, trias, mixed, or R-trias to specify the type of element to use in building meshes.

R-trias are right-angle triangular elements. Mixed uses quads primarily, but inserts trias when necessary to improve mesh quality. Quads attempts to use quads only, but may still insert some trias where quads simply will not fit.

mesh_type_trias

Trias

mesh_type_quads

Quads (equal densities)

mesh_type_right_trias

Right-trias

mesh_type_mixed

Mixed (density 10 at
top, 5 at bottom)

linear or no biasing / exponential biasing /bellcurve biasing

The biasing affects element growth in successive layers, moving away from the source faces.

thinsolid_nobias

No bias applied: all layers are equal in thickness.

thinsolid_exponentialbias

Exponential bias applied: successive layers are exponentially thicker.

thinsolid_bellcurvebias

Bellcurve bias applied: layers are progressively thicker near the center, but thinner near the source and destination faces.

bias intensity =

This numeric value affects how strongly the biasing effect (described above) is. When left at zero, no biasing is applied; the examples above use a bias intensity of 10.

elements to current comp / original comp

Specify if you want the newly created components to appear in the current component, or in the components of the shell elements.

The following action buttons appear throughout the subpanels:

Button	Action
offset+	Use this button to extrude/offset shells in the positive normal direction.
offset-	Use this button to extrude/offset shells in the negative normal direction.
thicken	On the thicken shells subpanel, this button performs the thickening when shells are on the midsurface.
mesh	On the thin solids subpanel, this creates the thin solid mesh in accordance with the criteria specified in the inputs.
reject	Undo any changes made to elements, or thin solid element creations. You cannot reject changes after exiting the panel, but you can still reject after switching to a different subpanel and returning.
return	Exit the panel.

Elem Offset Panel

Elem Offset Panel

Elem Offset Panel

Subpanels and Inputs

Panel Inputs

Input

Action

Panel Inputs

Input

Action

Panel Inputs

Input

Action

Panel Inputs

Input

Action

Panel Inputs

Input

Action

save src to SAVELIST

along surfs / source surfs

destination: surfs

number of layers:

element size = / elem_size/thickness

element type =

linear or no biasing / exponential biasing /bellcurve biasing

bias intensity =

Button

Action

See Also: