chapter 3: shell meshing · element quality control: check panel aspect ratio: this is the ratio of...

Copyright © 2009 Altair Engineering, Inc. Proprietary and Confidential. All rights reserved. Copyright © 2009 Altair Engineering, Inc. Proprietary and Confidential. All rights reserved.

Checking and Editing Mesh

Chapter 3: Shell Meshing

Copyright © 2009 Altair Engineering, Inc. Proprietary and Confidential. All rights reserved.

Checking and Editing the Mesh

Edges Faces

Penetration /

Intersection Check

Load

Summation

Summary

Count

Element

Check

Checks Toolbar

Length

Distance

Mass / Area

Calc

Features

Normals


Checking & Editing Mesh: Nodal connection for the 2D mesh

“Edges / T-connection” Panel or Tool - Edges

“Find Attached” Panel or Tool - Find

Allow you to verify the basic quality of your elements and to the geometric qualities of those

elements

Allow to display free edges to T-connection in the model by creating 1D elements on each one

For free edges you can also equivalence nodes within a specified tolerance


Element quality control: check panel

Allow you to verify the basic quality of your elements and to the geometric qualities of those

elements

Check element settings

Each check can be set to use a

different solver’s check method,

or you can set every check to

use the same method. When a

specified solver doesn’t support

a certain check at all,

HyperMesh uses its own method

for that check

“Check Elements” Panel or Tool - check elems

test the connectivity of a group of

elements check for duplicate elements



Chordal deviation is the perpendicular distance

between the actual curve and the

approximating line segments.

Jacobian: This measures the deviation of an element from its ideal or

"perfect" shape, such as a triangle’s deviation from equilateral.

The Jacobian value ranges from 0.0 to 1.0, where 1.0 represents a

perfectly shaped element.

Length min. :The shortest distance from a corner node

to its opposing edge (or face, in the case of tetra

elements); referred to as “height to closest node”.

Skew of triangular elements is calculated by finding

the minimum angle between the vector from each node

to the opposing mid-side, and the vector between the

two adjacent mid-sides at each node of the element.



Aspect Ratio: This is the ratio of the longest edge

of an element to either its shortest edge or the

shortest distance from a corner node to the

opposing edge ("height to closest node").

Taper ratio for the quadrilateral element is

defined by first finding the area of the

triangle formed at each corner grid point.

These areas are then compared to one half

of the area of the quadrilateral.

Warpage: this is the amount by which an element (or in the

case of solid elements, an element face) deviates from being

planar. Since three points define a plane, this check only

applies to quads. The quad is divided into two trias along its

diagonal, and the angle between the trias’ normals is

measured.

Interior Angles These maximum and minimum values

are evaluated independently for triangles and

quadrilaterals.


Checking & Editing Mesh: Element normal's

“Check Normals” Panel

Allow you to verify surface or elements normal's orientation and to adjust or reverse them


In HM10.0, there are options to remesh elements using the “automatic feature detection”,

“features” or the new option “lines”.

Automeshing: Remeshing

• Using any free form line, the automesh

functionality will remesh ensuring that

there is nodal seeding along the selected

line. The nodal seeding can be adjusted as

required

• Meshing regions where tight control over

mesh flow or mesh density will benefit

from this functionality. Other use cases

will also include defining weld/adhesive

lines.

This option in automesh panel allow you to remesh directly a selected group of elements

switch from surfs to elems


Checking & Editing Mesh: 2D page

“Smooth” panel 2D – smooth

• Improves quality of selected

elements

“Quality index” panel 2D – quality index

• Set criteria for all standard quality

checks

• Simultaneously evaluate element

quality

• Combine all checks into a single

value called “composite quality

index value”

• Edit nodes and elements

interactively or by automatically

maximizing element quality


Allow you to mesh surfaces to optimize the quality index (QI) of the elements generated

Automeshing: The Automesh Panel

“Automesh” Panel 2D – automesh – QI optimize

On the Criteria tab, you can set the target element size,

element criteria, and the method that is used to calculate

the values. An advanced criteria option can be enabled to

give more control over the intermediate QI values, but is

usually not necessary in order to obtain a good quality

mesh

Determines whether nodes generated on a surface edge can be moved

off the surface edge when the algorithm smoothes the mesh


Editing Mesh Tools: 1D, 2D, & 3D pages

“Edit element” panel 2D – edit element

• Combine – merge 2 or more elements into 1 single element

• Split – draw a line to cut elements

• Cleanup – interactively drag nodes to improve element quality

“Split” panel 2D – split

• Divide selected elements in a selected manner

“Replace” panel 2D – replace

• Merge 2 nodes into 1 node (elements are now connected)

“Detach” panel 2D – detach

• Disconnect selected elements from other elements


Checking & Editing Mesh: Utility Menu

• Add washer – add a ring of quad elements around

a hole in existing mesh

• Trim Hole – add a hole to existing mesh

• Fill Hole – remove a hole from existing mesh

• Box Trim – cut elements passing through a box

shape

• Bead – add a bead shaped mesh to an existing

mesh

“Utility” Menu Geom/Mesh page – Mesh Tools

chapter 3: shell meshing · element quality control: check panel aspect ratio: this is the ratio of...

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