automesh子面板详细解释

HyperMesh and BatchMesher

Automesh Panel

HyperWorks Desktop Applications >HyperMesh>User's Guide>HyperMesh Panels>HyperMesh Panels

Listed Alphabetically:

Automesh Panel

Location

:

The

Automesh

panel can be accessed from the menu bar by clicking

Mesh

>

Cre ate

>

2D Automesh

, or by pressing the

F12

function key.

The

Automesh

panel is used to generate a mesh of plate elements using surface

geometry or existing shell elements to define the mesh area.

Panel Usage

The options in the panel can be set in any order that you feel comfortable using.

Moving from subpanel to subpanel will not cause you to lose work. When finished

making all your selections, start the meshing process using the

mesh

button on the

right side of the panel.

?

Set the panel mode by selecting the appropriate

subpanel

?

Select the meshing method by setting the entity selector to

surfs

or

elems

?

Make the required element criteria settings

?

Set any algorithm options

?

Select the area to be meshed using the entity selector and any extended

selection methods desired.

The

unmeshed

and

failed

selection buttons on the right side of the panel

Note:

can be used to make pre-defined surface selections if desired.

Use the interactive image below to see the various options on each subpanel. To

start, click either

elems

or

surfs

in the upper left corner. To reset the image, click

the

return

button.

Subpanels and Inputs

The

Automesh

panel contains the following subpanels:

Size and Bias

Size and bias meshing is a very flexible and powerful meshing method. A minimum

of inputs are required for the element criteria settings. The algorithm options can

set preferences on how to handle certain situations when encountered in the

geometry. When using existing finite elements as the basis for mesh generation,

feature recognition settings allow the mesher to break up the areas defined by the

selected elements into logical groupings with mesh controls set for each group

meshing mode works interactively or automatically. In interactive

mode, a great deal of manual control is presented via the

Secondary Automesh

panel during the mesh generation stage. Interactive meshing allows you to control

mesh size and element type, and to set different mesh generation algorithms and

test element quality on a surface-by-surface basis. The resulting modified mesh can

be updated at any time, giving immediate feedback as to the effectiveness of the

change. When meshing in the automatic mode, the mesh will be generated using

only the settings, criteria and options set in the Automeshpanel.

Size and biasing produces a mesh with consistent element size. If meshed

interactively, the number of elements (element density) node spacing (biasing),

element type and mesh style can be modified for each surface face and edge.

Panel Inputs

Input

Action

entity

selector

Set to use

surfaces

or existing finite

elements

to define the area to

mesh. Extended entity selection options are available to populate

the selection.

feature

s

When using existing finite elements as a basis for automeshing,

feature recognition is used to define logical faces.

Use this switch to

determine how the automesher treats features:

?

connected features

automatically detects features based on

the specified

feature angle

and make additional effort to void

any

It works similarly to

auto

detect features, but includes a more rigorous check to

combine small areas and avoid creating features that end

abruptly or do not connect to any other features.

?

auto detect

features automatically detects features based on

the specified

feature angle

. In some cases this can create

?

feature edges

allows you to pick surface edges in the model to

preserve as features.

?

lines

allows you to pick lines in the model geometry to preserve

as features.

mesh

mode

toggle -

interact

ive /

automa

tic

Interactive

mode will expose the interactive Automeshing

secondary panel once the meshing has started.

Automatic

mode uses only the settings and selections made in the

panel to complete the meshing process.

element

size

Enter a floating point numeric value for the average element size.

The length of any active (shared or free) surface edge will be divided

by this number to determine the number of elements to place along

that edge.

mesh

type

Select

quads

,

trias

,

mixed

,

R-trias

,

Quads only

, or

advanced

to

specify the type of element to use in building meshes.

?

Mixed

uses quads primarily, but inserts trias when making

density transitions, resulting in

improved mesh quality.

?

Quads

attempts to use quads only--however, at least one tria

element must be created if the sum of the element densities

around the perimeter of the face or surface is odd.

The sum of element densities on the perimeter of the

lower surface is odd, resulting in a tria as indicated.

Adjusting the element densities while meshing interactively

can usually elimate all tria elements.

Adjusting the bottom edge density from 11 to 10 makes

the sum even and allows all-quads to be generated.

?

Quadsonly

uses a subdividing routine that tends to generate

more orthogonal quad elements.

Tria elements may still be introduced depending on the

density settings as with the quads type.

?

Tria

elements uses all-trias to mesh.

?

R-trias

are right-angle triangular elements.

If you select

Advanced

, choose any of the other types individually

for

mapped

elements (elements on surfaces that can be mapped to

simple geometric shapes) and

free

elements (those that cannot

easily map to simple shapes).

tA

mapped

type

Choose the type of elements (as for

Mesh type

above) to use for

surfaces that

can be mapped to simple geometric shapes.

map as circle - free

map as circle - mapped

map as rectangle - free

map as rectangle - mapped

map as pentagon - free

map as pentagon - mapped

free

type

Choose the type of elements (as for

Mesh type

above) to use for

surfaces that cannot be mapped to simple geometric shapes.

feature

angle

Specify a maximum angle across which elements can be

maintained.

Any time two adjacent elements’ normals would exceed this angle

HyperMesh creates a new set of nodes between them to maintain

clean feature lines.

Using a higher value results in elements

spanning the feature line:

With an appropriate value, the features lines are preserved.

If

feature angle =

is too high, the feature lines are blurred.

vertex

angle

When using

connected features

or

auto detect features

, this

setting is a maximum element vertex angle.

Whenever an element

vertex exceeds this angle while adhering to features, the element

will be split into two elements with correspondingly smaller vertices.

elems

to surf

comp /

elems

to

current

comp

Select the destination component for the newly created elements as

the “current” active component or the component to which the

surface belongs. The current component is indicated in the

component list of the

Model

browser, or the component status

display of the status bar.

first

order

/second

Set to create first order (linear shape function) or second order

(polynomial shape function) elements.

order

connect

ivity

Select how the connectivity between the newly created elements

and any adjacent existing elements will be handled. Choices include:

?

keep connectivity

: use the existing nodes on any shared

boundary edges.

?

redo connectivity

: re-seeds any existing nodes along the

boundary of the newly created mesh to optimize mesh quality.

?

break connectivity

: ignore any existing adjacent elements

and generate the mesh according to the size and type specified.

?

previous settings

: re-use any previous node density and

spacing settings associated to the selected surface edges.

flow:

align

Produce a more orthogonal quad-dominant mesh. Only applies to

mixed

element type.

Here, there is no flow alignment

Flow alignment is used, producing straighter rows of elements

?

flow

: align produces a more orthogonal quad dominated mesh

?

flow

: size appears only when align is active, and enforces the

global mesh element size with minimal min/max element size

variation.

map:

size

Keeps the elements roughly the same size.

map:

skew

Prevents the mesh from producing highly-skewed elements.

anchor

nodes

Designate nodes that will remain and be re-used in the new

mesh.

Anchor nodes are

move or replace them; in essence, they are exceptions to the

re-meshing operation, and the new mesh must utilize them.

link

opposit

e edges

with AR

<

Links mesh settings on opposing edges of rectangular surfaces. Any

changes applied to one linked edge will be applied to the other. A

control is available to define the maximum aspect ratio (AR) to allow

between large and small edge sizes of linked edges.

auto

corresponds to a value of 2.11. Increasing the value will add more

surfaces to the linked chain, whereas decreasing the value will

remove some surfaces from the linked chain.

Mesh without

link

opposite edges

Mesh with

linkopposite

edges

Mesh with

link opposite

edges

with AR <

selected.

with AR <

set to

auto

.

with AR <

set to

8.0

.

QIOptimize

Quality Index meshing is an iterative automatic mesh generation method driven by

element quality criteria. During the mesh generation process, the quality index of

the mesh is determined by evaluating each element against a set of element quality

tests.

If all required element quality criteria are passed, then that element has a

perfect quality index of zero. As the element quality deteriorates, the quality index

value increases; so a lower quality index score indicates an element more closely

meets the ideal quality requirements.

The compound quality index sum of the quality index values for each of the

elements that are included in the current meshing area. The quality index value

itself has no direct physical meaning; it is a way to compare one generated mesh

pattern against another pattern generated for that same area. The quality index

based mesh optimization routine attempts modify the mesh pattern and apply node

smoothing routines to obtain a lower overall quality index value.

For more on element quality index, see the

Quality Index

panel.

Panel Inputs

Input

Action

entity

selector

Set to use

surfaces

or existing finite

elements

to define the

area to mesh.

Extended entity selection options are

available to populate the selection.

features

The automesher will seed nodes along features so as to avoid

spreading elements across them.

When the entity selector is

set to

elems

, use this switch to determine how the

automesher treats features:

?

connected features

automatically detects features

based on the specified

feature angle

and make

additional effort to void any

feature lines.

It works similarly to

auto detectfeatures

,

but includes a more rigorous check to combine small areas

and avoid creating features that end abruptly or do not

connect to any other features.

?

auto detect features

automatically detects features

based on the specified

feature angle

. In some cases this

can create

?

feature edges

allows you to pick surface edges in the

model to preserve as features.

?

lines

allows you to pick lines in the model geometry to

preserve as features.

element size

Enter a floating point numeric value for the average element

size. The length of any active (shared or free) surface edge

will be divided by this number to determine the number of

elements to place along that edge.

mesh type

Select

quads

,

trias

,

mixed

, or

Quads only

to specify the

type of element to use in building meshes.

?

Mixed

uses quads primarily, but inserts trias when

making density transitions, resulting in

improved mesh

quality.

?

Quads

attempts to use quads only--however, at least

one tria element must be created if the sum of the

element densities around the perimeter of the face or

surface is odd.

Adjusting the element densities while meshing

interactively can usually eliminate all tria elements.

?

Quadsonly

uses a subdividing routine that tends to

generate more orthogonal quad elements.

Tria elements may still be introduced depending on

the density settings as with the quads type.

?

Tria

elements uses all-trias to mesh.

Use current

criteria /

Criteria file:

Use this toggle to choose between using the current element

quality criteria or specifying a criteria file that has been

previously created. When set to use

current criteria

, the

green

edit criteria

button is presented.

Edit criteria

This button only displays when

use current criteria

is

selected, and opens the

Criteria File Editor

.

feature angle

Specify a maximum angle across which elements can be

maintained.

Any time two adjacent elements’ normals would exceed this

angle HyperMesh creates a new set of nodes between them to

maintain clean feature lines.

Using a higher value results in

elements spanning the feature line:

With an appropriate value, the features lines are preserved.

If

feature angle =

is too high, the feature lines are blurred.

vertex angle

When using

connected features

or

auto detect features

,

this setting is a maximum element vertex angle.

Whenever

an element vertex exceeds this angle while adhering to

features, the element will be split into two elements with

correspondingly smaller vertices.

Smooth

across

common

edges with

check this option to allow node smoothing to move nodes

across adjacent surface edges whose

feature angle

is less

than the value specified. When this option is active, strict

adherence to the geometry of the surface edges in not

enforced for non-feature edges; some deviation from the

geometry can occur.

elems to surf

comp / elems

to current

comp

Select the destination component for the newly created

elements as the “current” active component or the

component to which the surface belongs. The current

component is indicated in the component list of the Model

browser, or the component status display of the status bar.

first order

/second

order

Set to create first order (linear shape function) or second

order (polynomial shape function) elements.

connectivity

Select how the connectivity between the newly created

elements and any adjacent existing elements will be handled.

Choices include:

?

keep connectivity

: use the existing nodes on any

shared boundary edges.

?

redo connectivity

: re-seeds any existing nodes along

the boundary of the newly created mesh to optimize mesh

quality.

?

break connectivity

: ignore any existing adjacent

elements and generate the mesh according to the size and

type specified.

?

previous settings

: re-use any previous node density

and spacing settings associated to the selected surface

edges.

flow: align

Produce a more orthogonal quad-dominant mesh. Only

applies to

mixed

element type.

Here, there is no flow alignment

Flow alignment is used, producing straighter rows of elements

?

flow: align

produces a more orthogonal quad dominated

mesh

?

flow: size

appears only when

align

is active, and

enforces the global mesh element size with minimal

min/max element size variation.

anchor nodes

Designate nodes that will remain and be re-used in the new

mesh.

Anchor nodes are

cannot move or replace them; in essence, they are exceptions

to the re-meshing operation, and the new mesh must utilize

them.

Edge Deviation

Use the

Edge Deviation

subpanel to set specific meshing parameters to limit how

far the mesh elements can deviate from the actual edges of the surfaces meshed, or

when in the case of re-meshing elements, deviation from inferred edges based on

features.

Controls for the

minimum

and

maximum

allowable element size,

edge deviation

and

maximum angle

are introduced with this method.

Edge deviation normally

occurs on curved edges, because individual elements have straight edges and

therefore can only approximate a curve.

When meshing curved surfaces as shown here, the planar

elements (tan color) can deviate from the curved grey

geometry.

Edge deviation applies to both surface geometry and when re-meshing elements.

Automeshing on the

edge deviation

subpanel automatically selects the best

element size to approximate a curve, within the limits that you specify. The

max

deviation

and

max angle

settings are the primary controls for this effect.

This differs from the

size and bias

subpanel,

which only meshes with elements of a uniform

Note:

size that you specify.

This method can produce a mesh in which the element size varies, even within the

same surface. Areas of high curvature will tend to have smaller elements than areas

of low or no curvature. The

element size

boundaries allow you to control this

effect.

Edge deviation control when meshing creates smaller elements and spaces nodes closer together to limit

how much the elements can deviate from the surface edges.

Panel Inputs

Input

Action

entity

selector

Set to use

surfaces

or existing finite

elements

to define the area to

mesh.

Extended entity selection options are available to populate

the selection.

feature

s

The automesher will seed nodes along features so as to avoid

spreading elements across them.

When the entity selector is set to

elems

, use this switch to determine how the automesher treats

features:

?

connected features

automatically detects features based on

the specified

feature angle

and make additional effort to void

any

auto detect features

, but includes a more rigorous check to

combine small areas and avoid creating features that end

abruptly or do not connect to any other features.

?

auto detect

features automatically detects features based on

the specified

feature angle

.

In some cases this can create

?

feature edges

allows you to pick surface edges in the model to

preserve as features.

?

lines

allows you to pick lines in the model geometry to preserve

as features.

mesh

mode

toggle -

interact

ive /

automa

tic

Interactive

mode will expose the interactive Automesh panel once

the meshing has started.

Automatic

mode does not allow you to modify the mesh after it is

created.

min /

max

element

size

Specify the element size boundaries. The values specified here are

rigidly enforced, even if other settings (that is

max deviation

) are

violated.

max

deviatio

n

The allowable deviation between the element edge and the surface

edge. To meet this requirement, element edge lengths along a

curved surface edge are reduced as needed down to a lower limit set

by the

min elem

size field.

max

angle

Defines the maximum allowable angle between two element

edges.

This also helps determine the size of an element to create;

if the angle formed by adjacent element edges would exceed this

value, smaller elements are tried until the angle is equal to or less

than this value.

mesh

type

Select

quads

,

trias

,

mixed

,

R-trias

,

Quads only

, or

advanced

to

specify the type of element to use in building meshes.

?

Mixed

uses quads primarily, but inserts trias when making

density transitions, resulting in

improved mesh quality.

?

Quads

attempts to use quads only--however, at least one tria

element must be created if the sum of the element densities

around the perimeter of the face or surface is odd.

Adjusting the element densities while meshing interactively

can usually eliminate all tria elements.