AnsysWorkbench学心笔记

Ansys Workbench Study

1.

SpaceClaim

Source->Make Independent;

Component, Analysis, Share Topology, Share: for meshing;

Create a coordinate system at the centre of selected objects;

Use

‘Prepare’

&

‘Repair’,

especially

’Imprint’

for

splitting

surfaces

and

‘Split

Body’

for

simplification;

No need to deal with contacts;

Do not remove duplicate faces using ‘Duplicates’, which may cause body converted to surface;

Table 1 Processes for modification in Ansys SpaceClaim

Name

Icon

Illustration

Make this copy of the component independent from all other copies

Make Independent

of this component.

Multi-body

Component

Put all the independent bodies into one component.

Share Topology

Choose “Share” from the drop

-down list to share topology for

different bodies.

Create a coordinate system at the centre of the selected objects.

Click a face, plane or an edge loop to split the body. Optionally click

regions to remove.

Merge or split objects.

Create a midsurface from groups of offset surfaces.

Detect coincident faces, edges or vertices and imprint them to allow

for mesh connections.

Origin

Split Body

Combine

Midsurface

Imprint

Interference

Rounds

Detect and fix interfering bodies.

Remove rounds from a model.

Remove features from a model by filling features or extending

Faces

neighbouring faces.

Display overlapped faces.

Search an assembly for small gaps between parts.

Stitch surfaces into a single body.

Detect and fix gaps in a surface body.

Detect and fix missing faces in a surface body.

Detect and fix coincident edges that do not mark the boundaries of

Overlap Faces

Clearance

Stitch

Gaps

Missing Faces

Split Edges

new faces.

Detect and remove edges that are not needed to define the shape of

Extra Edges

this model.

Some other functions in “Prepare” and “Repair” in the menu bar may

apply.

…

…

2.

Mechanical

：

Steady-State Thermal

Engineering Data:

Change the *.xml file version to Ansys version

For creep model, it’s one period of time that counts not transient state.

Units: ?

mks

Geometry:

Material assignment;

Named Selection: for name selection when setting boundary conditions and post

Reference temperature: for zero thermal strain reference temperature, use welding temperatures

Symmetry:

Model-

>Symmetry,

Num Repeat

2,

Method Half,

ΔX

=

1e

-14m, Workbench

Tools Appearance

Beta check;

Table 2 Processes for symmetry boundary conditions in Ansys Mechanical

Name

Icon

Illustration

To display the whole module, set Num Repeat = 2, Method = Half, ΔX(Y) =

Symmetry

1e-14m, and check Workbench > Tools > Appearance > Beta.

Meshing:

Number of Divisions 3; Geometry, select one edge and Size, select all entities with the same size;

Bias Type and Bias Factor;

Meshing method: MultiZome/Sweep; hexagonal mesh is better; If use tetrahedral mesh, do not

use degraded tetrahedral elements

Table 3 Processes for modification in Ansys Mechanical

Name

Sizing

Icon

Illustration

Number of divisions & Bias for mesh on edges

Method

MultiZone for the whole module

Boundary conditions:

For convection surfaces, select the

surfaces layer by layer, cross

use ‘Single

Select’ and ‘Box

select’,

make

full

use

of

‘Hide

Boday'

and

‘Hide

All

Other

Bodies’,

and

alternating

‘Face’

and

‘Body’;

No need deal with contacts;

Table 4 Processes for thermal initial and boundary conditions in Ansys Mechanical

Name

Initial Temperature

Icon

Illustration

The initial temperature is set as

.

Heat source from diode is 26.17 W/per diode and heat source

Internal Heat Generation

from IGBT is 96.83 W/per IGBT. For transient, the power is on

and off alternately and each state last one second.

Temperature

Perfectly Insulated

Analysis Settings:

The bottom surface of the baseplate is set as

.

All other surfaces of the model are set as insulated.

Radiosity Controls for convergence

Solution:

Solution Information: Solution Output to choose convergence curves;

3.

Mechanical: Static Structural

A

quasi-static

process

is

a

process

that

happens

slowly

enough

for

the

system

to

remain

in

internal

equilibrium.

The

thermal

stress

process

can

be

seen

as

quasi- static

process,

which

means: when the temperature changes, the stress and strain changes immediately. Therefore, it

doesn’t matter to use ‘Static Structural’ or ‘Transient Structural’ as

they give the same result.

Ansys Workbench:

From ‘Steady

-

State Thermal’ right click ‘Solution’ select ‘Transfer Data to New’ ‘Static Structural’;

Imported Load: Imported Body Temperature, Source Time: All

Thermal Conditions:

At the high temperature dwell time, relaxation will be fast compared to the low temperature range;

thus,

a

stress-free

state

much

closer

to

the

high

temperature

setpoint

will

settle

in,

with

an

overlay

of

thermal

and

mechanical

excursions.

Stresses

will

of

course

be

higher

in

the

low

temperature range. (Poech & Eisele, 2000)

Boundary Conditions:

Restrict the 6 DOF, Frictionless Support for two symmetrical surfaces, Displacement z=0 for one

point;

Or follow Figure 1 for any object.

Figure 1 Restriction of the 6 DOF

Table 5 Processes for structural boundary conditions in Ansys Mechanical

Name

Icon

Illustration

To restrict the degree of freedom in the surfaces’ normal

Frictionless Support

directions

To restrict the degree of freedom in vertical directions

Displacement

Element Birth and Death:

To activate/deactivate elements in a step.

Analysis Settings:

Set multi-step for changing loading to capture specific time points.

Initial time

step: 1e-2s, Minimum time step, 1e-30s; Maximum time

step: around 100s for long

thermal cycles;

Step

Controls

can

be

defined

by

Time/Substeps

for

convergence;

Nonliear

Controls

Force

Tolerance can be increased to 5%;

Large Deflection: On, for large deflection convergence;

Restart Controls: add load separately, can be used for substep save in case the program exit by

accident, but it will enlarge the file size dramatically!

Output controls: Specified Recurrence Rate, 2 to reduce the output file size by half.

Solution:

Neglect the warning about the CTE reference temperature.

User defined result: NLPLWK (non-linear plastic work)

APDL:

To output specific times:

! Commands inserted into this file will be executed just prior to the ANSYS SOLVE command.

! These commands may supersede command settings set by Workbench.

/NERR,,1000000

OUTRES,erase

*dim,t_out,,17! RESULTS OUTPUT TIME ARRAY

t_out(1) = 1800, 3600, 10800, 10801, 14400, 14401, 18000, 18001, 21600, 21601, 25200, 25201, 28800, 28801, 32400, 32401,

39600

OUTRES,all,%t_out% ! OUTPUT RESULTS AT TIME SPECIFIED BY THE ARRAY

! Active UNIT system in Workbench when this object was created: Metric (m, kg, N, s, V, A)

! NOTE: Any data that requires units (such as mass) is assumed to be in the consistent solver unit system.

! See Solving Units in the help system for more information.

Note: the output result will also be these specified time points! How to solve this problem?

Miscellaneous

：

Tools, Options, Mechanical, Miscellaneous, Save Options: for auto save

4.

Mechanical

：

Transient-State Thermal

Ansys Workbench:

Analysis

Settings:

loads

can

change

against

time

in

one

step;

Set

the

end

time

for

one

step;

Loads

can

be

added

directly

in

Tabular

Data;

Steps

can

be

used

for

different

processes

with

Element Birth and Death. Time steps can be controlled, APDL commands need to be added for

specific times.

Magnitude: Tabular Data/Function