Map Mid-Mesh Thickness Tool

Use the Map Mid-Mesh Thickness tool to calculate the thickness of a mid-mesh from the solid geometry. The thickness will be assigned on the mid-mesh either on node card, element card, nodal thickness on element card or also as properties on elements depending on the user profile you are using. You can access the Mid-Mesh Thickness tool by clicking Mesh > Edit > Elements > Midmesh Thickness from the menu bar when the OptiStruct, RADIOSS, Abaqus, LS-DYNA, PAM-CRASH2G, or Nastran user profiles are loaded.

The Map Mid-Mesh Thickness tool is divided into the following sections:

The mid-mesh and solid can be specified by manually selecting entities from the current HyperMesh session, or by selecting external geometry or FE solver decks as input.

map_midmesh_thickness_input

FE and Geometry displayed
Traditional Element Visualization

From the Thickness Output section, define thickness output. Click Calculate Thickness to begin the operation. The thickness will be computed and assigned on the mid-mesh.

Select one of the following thickness output options:

Output	Description	User Profile
Node	Assigns a thickness on node cards.	Abaqus
Element	Assigns a single thickness on element card.	RADIOSS, Abaqus, LS-DYNA, PAM-CRASH2G (TSHELL and SHELL card image)
Nodal Thickness on Elements	Assigns multiple thicknesses on elements for each node.	OptiStruct, LS-DYNA, Nastran
Properties on Elements	Creates properties for groups of elements, and assigns a thickness to each property.	OptiStruct, Nastran, Abaqus
Properties on Components	Creates components and properties for groups of elements, assigns a thickness to each property, and then assigns the property to a component.	LS-DYNA
Select Card Image	Assigns a thickness on INISHE entities, when you select one of the following card images from the list: SHELL, EPESP_F, STRA_F, and STRS_F.	RADIOSS
Thickness on Components	Assigns thickness on PART (SHELL, TSHEL, and MEMBR)	PAM-CRASH2G
Contact Thickness on Components	Assigns contact thickness to TCONT on PART (SHELL, TSHELL, and MEMBR)	PAM-CRASH2G

Specify a minimum thickness to assign calculated thicknesses below the specified value.

Specify a maximum thickness to assign calculated thicknesses above the specified value.

Assigns an offset value to element cards.

map_midmesh_thickness_noassignoffset

Note that the mesh deviates from the geometry; the mid-mesh node is equidistant from mesh corners, but not from
the nodes on the geometry corners.
- 2D Detailed Element Representation is active
- No Element Offset is active

map_midmesh_thickness_assignoffset

Here, the offset has caused the mesh to match the geometry, though the initial mid-mesh node remains unchanged.
such that it now matches the geometry.
- 2D Detailed Element Representation is active
- An Element Offset is active

Approximates the thickness values on individual elements to be an average value representing a group of elements.

Only available when thickness output is Elements.

Controls the number of thickness properties or groups. Enabling this option ensures that no thickness group or property will have a thickness interval range greater than the specified value. In other words it is the maximum limit on the max thickness – min thickness in a thickness group or property.

Selecting Abs (absolute) groups thicknesses in the given intervals; selecting Rel (relative) calculates the absolute thickness interval value by multiplying the given value with the average thickness of the group (that is, the given value is the ratio of the interval value to the average thickness of the group).

Only available when thickness output is Properties on elements or when Assign average thickness to element groups is selected.

Rounds the thickness values up or down to have the same number of decimal digits as the input value in the Maximum thickness range interval field.

Only available when Maximum Thickness Range Interval is selected.

The information logged during the computation can be directed the supplied file.

map_midmesh_thickness_log

Advanced Options

On elements or nodes where the thickness could not be computed correctly, there are different options to correct it:

•	Interpolate from Neighbors: An appropriate thickness value is interpolated from the neighboring element/node thickness.

•	Adjust to min/max values: If either minimum or maximum thickness is defined it is assigned on the corrected elements.

Applies a scaling algorithm when interpolating thickness values near t-junctions or corners.

•	Supplying a value less than 1 will result in linear decrease in the thickness values nearer to the junctions / corners.

•	A value of zero will result in an approximate mass-conserved thickness estimation.


Scaling at corners = 0 Thickness Contour Applied Traditional Element Visualization	Scaling at corners = 0 Thickness Contour Applied 2D Detailed Element Representation

When equal to 1, the thickness is extrapolated / interpolated without any scaling.


Scaling at corners = 1 Thickness Contour Applied Traditional Element Visualization	Scaling at corners = 1 Thickness Contour Applied 2D Detailed Element Representation

When greater than 1, the thickness will increase as you go closer to the junction.

Only available when the Correction method is set to Interpolate from Neighbors.

Defines the cut-off angle in degrees.

Enter the maximum angle (0 to 90) that the mid-mesh makes with the solid, beyond which the estimated thickness will be ignored and corrected.

For example, the images below show the midmesh in blue, and the solid in black. In the first image the midmesh and the solid form a moderate angle. However in the second image the midmesh and the solid form a larger angle. It is possible that this area is a junction, located at the solid edge, or the solid may contain some noisy features, therefore you may want to ignore the calculated thickness and interpolate that value from surroundings.

tool_map_mid_mesh_thickness_max_midmesh_solid_angle_option

Measures the change in adjacent thickness values, and restricts the gradient.

Enter the maximum change in thickness allowed across two adjacent measurement locations, as a factor of the distance between the locations. Allowable factors range from 0 to 10.

For example, the image below shows a tiny projected boss in an otherwise planar area, which you may want to ignore. Defining the Max thickness gradient specifies the cut-off for the ratio of difference in thickness at two locations to the distance between the two locations. If the ratio is more than the given value, the measured thickness is discarded, and interpolated from its neighbors.

tool_map_mid_mesh_thickness_max_thickness_gradient_option

Specify a maximum relative faceting error to use during faceting calculations.

When HyperMesh computes the proximity with a solid, it do not actually compute with the surface geometry. Instead, HyperMesh computes with the tessellated approximation (facets) of the geometry. In case of curved geometry, the facets may not exactly match the geometry, and hence the thickness is computed, causing faceting errors. Specifying the Max relative faceting error enables you to control the accuracy of the tessellation used, as a factor of the estimated thickness. The Max relative faceting error is the ratio of the maximum error of facets to the estimated thickness. If it exceeds this value, facets are further refined to better capture the geometry.

Specify the maximum distance which will be considered for searching solid proximity. This value is also used to restrict the maximum distance from which a good thickness value is considered for correcting an incorrect thickness estimate. You can also used this option to restrict the algorithm from assigning incorrect thicknesses for the mid-mesh that is out of the solid proximity.

When this option is enabled, a thickness will not be assigned to the Mid-mesh outside of the solid.

Settings

From the View section, define visualization settings for the Mid-mesh.

Sets the Element Color mode to By Thickness resulting in a contour plot of thickness.

map_midmesh_thickness_elemcolorbythickness

Thickness Contour Applied
2D Detailed Element Representation

Displays mid-mesh elements as 2D with the assigned thickness as depth.

map_midmesh_thickness_3delem_representation

2D Detailed Element Representation

Assigning a thickness for each individual node or element, enables you to assign a variable thickness to elements. You can visualize both the element and nodal thickness in the graphics area by selecting 2D Detailed Element Representation from the Visualization toolbar.

The behavior of 2D Detailed Element Representation depends on what you assigned a thickness to. For example, if you assign a component an element thickness, then the element thickness representation will be displayed. If you assign a nodal thickness to an element node, then each individual node thickness will be plotted and you will be able to see the first and second order trias and quad elements. When you assign a nodal thickness, you can select the By Thickness option in the Visualization toolbar to display each node value. If you assign a nodal thickness, and offset is on, then the element thickness from the nodes will be calculated, the element will be offset, and the nodal thickness 2D Detailed Element representation on the offset elements will be plotted.

Limitations

Currently, composites with variable thickness are not added for this new feature.

Highlights the elements whereby the thickness could not be calculated from solid, and deploys the correction method.

map_midmesh_thickness_highlight_corrected

2D Detailed Element Representation
Corrected Elements Highlighted