09 mech-intro 13.0 l03 genprep

8/11/2019 09 Mech-Intro 13.0 L03 GenPrep

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L3-1ANSYS, Inc. Proprietary

2010 ANSYS, Inc. All rights reserved.Release 13.0

November 2010

Introduction to ANSYSMechanical

Customer Training Material

Lecture 3

General Preprocessing


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Introduction to ANSYS Mechanical



November 2010

Customer Training MaterialChapter Overview

In this chapter, using features without the use of the Wizards will be

covered

Topics:

A. Geometry

B. Contact

C. Coordinate Systems

D. Named SelectionsE. Workshop 3-1, Contact Control

The capabilities described in this section are generally applicable to

the ANSYS DesignSpace Entra licenses and above and are noted in

the lower-left hand tables


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November 2010

Customer Training Material Introduction

The Outl in e Treeis the main way of setting up an analysis

The Context Toolbar, Details View, and Graphics Window update,depending on which Outline Tree branch is selected

Use of the Outline Tree will be emphasized in this chapter

Use of the Outline Tree is

the means by which

users navigate through

the Mechanical GUI.


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November 2010

Customer Training MaterialA. Geometry Branch

The Geometry branch lists the part(s)

that make up the model.

In Mechanical, there are three types of

bodieswhich can be analyzed:

Solid bodies are general 3D or 2D

volumes/areas/parts

Surface bodies are only areas

Line bodies are only curves

Each is explained next . . .


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November 2010

Customer Training Material Types of Bodies

Solid bodies are geometrically and spatially 3D or 2D:

3D solids are meshed with higher-order tetrahedral or hexahedral solid elements

with quadratic shape functions.

2D solids are meshed with higher order triangle or quadrilateral solid elements

with quadratic shape functions

The 2D switch must be set on the Project page prior to import

Geometry type cannot be changed from 2D to 3D (or vice versa) after import

Each node has three translational degrees of freedom (DOF) for structural or one

temperature DOF for thermal

3D Solids 2D Solids

Axisymmetric

cross section


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November 2010

Customer Training Material Types of Bodies

Surface bodies are geometrically 2D but spatially 3D:

Surface bodies represent structures which are thin in one dimension (through-

thickness). Thickness is not modeled but supp l ied as an input value.

Surface bodies are meshed with linear shell elements having six DOF (UX, UY,

UZ, ROTX, ROTY, ROTZ).

Line bodies are geometrically 1D but spatially 3D:

Line bodies represent structures which are thin in two dimensions. The cross-

section is not modeled.

Line bodies are modeled with linear beam elements having six DOF (UX, UY, UZ,

ROTX, ROTY, ROTZ).

Line BodySurface Body


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November 2010

Customer Training Material Multibody Parts

In general, bodiesand partsare the same. In DesignModeler however,multiple bodies may be grouped into mult ibody par ts.

Multibody parts share common boundaries so nodes are shared at thatinterface.

No contact is needed in these situations.

Example:

Common nodes

are shared by

adjacent bodies


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November 2010

Customer Training Material Material Properties

To assign material properties to a body

highlight it and select from the available

properties in the Assignment field :

The only materials appearing in the list

will be materials added using the

Engineering Data application (see

chapter 2).

For surface bodies a thickness needs to

be supplied as well.


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November 2010

Customer Training Material Geometry Worksheet

A summary of bodies and assigned materials is available.

Select Geometry branch and toggle the Worksheet icon. Toggle between graphics or worksheet via tabs at bottom


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November 2010

Customer Training MaterialB. Contact

When multiple parts are present, a means of defining the relationship

between parts is needed.

Contact regionsdefine how parts interact with each other.

Without contact or spot welds, parts will not interact with each other:

In structural analyses, contact and spot welds prevent parts from penetrating

through each other and provide a means of load transfer between parts.

In thermal analyses, contact and spot welds allow for heat transfer across parts.

Multibody parts do not require contact or spot welds.

BA

Surface contact elements can be visualized as a skin

covering the regions where contact will occur.

Load


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November 2010

Customer Training Material Contact

When an assembly is imported contactsurfaces are automatically detected

and created: The proximity of surfaces is used to

detect contact. Tolerance for contactdetection is available in theConnections branch details.

Contact is also used for 2D geometry.Contact surfaces are represented byedges.

Certain license levels allow surface toedge, edge to edge and mixedsolid/surface contact.

Note, autom atic co ntact shou ld always

be checked and ver i f ied before

proceeding w ith an analys is.


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November 2010

Customer Training Material Contact

Connections can be grouped for convenient contact management.

In the example shown, contact has been grouped relative to varioussub assemblies in the model.

Contact can be auto defined for each group via RMB.


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November 2010

Customer Training Material Solid Body Contact

Contact elements provide the relationship between parts.

Each part maintains a separate mesh. This means that one small part will not

drive mesh density of the entire assembly and/or the user can make parts ofinterest have a finer mesh than other parts

Note the non-matching mesh at the

interface between parts.

Mix of hexahedral elements

contacting tetrahedral elements is

possible.


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November 2010


When a contact region is highlighted in the connections branch, parts are made

translucent for easier viewing.

Selecting a contact region makes non participating bodies translucent.

Contact surfaces are color coded for easy identification.


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November 2010


Go To utilities allow a more detailed investigation of contact definitions:

Corresponding bodies in tree

Bodies without contact

Parts without contact

Contact regions for selected bodies

Contacts common to selected bodies

Contacts can be quickly renamed to match part names

RMB


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November 2010


To manually define a contact pair insert a manual contact region and selectand apply contact and target surfaces.

RMB


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November 2010

Customer Training Material Advanced Solid Body Contact

For ANSYS Professio nallicenses and above,

advanced contact options are available:

Auto detection dimension and slider

Pinball control

Asymmetric contact, contact results tool and

additional formulations will be covered in a later

chapter.

Details for ConnectionsDetails for Contact Regions


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November 2010

Customer Training Material Advanced Solid Body Contact

The Pinball region represents a contact detection zone:

Contact open status is determined by the pinball radius.

Outside pinball: far field Inside pinball (not touching): near field

Closed status is either sliding or sticking.

The pinball radius may be entered so that bonded contact

is used in gaps.

Pinball radius is displayed as a sphere in the graphics

window.


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November 2010

Customer Training Material Surface Body Contact

Shell contact includes edge-to-face or edge-to-edge

contact: Shell contact is not turned on by default.

User can turn on detection of face-to-edge or edge-to-edge

contact.

Priority can be set to prevent multiple contact regions in a

given region.

Edge to Surface Edge to Edge Edge to Surface


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November 2010

Customer Training Material. . . Mesh Connections

Mesh connections can be used to joint surface

bodies at the mesh that do not share topology.

Must be a multibody part (DM).

Can include gaps/penetration.

Can use automatic or manual creation.

For manual definition:

Master geometry can be faces

or edges.

Slave geometry can only be

edges.

I d i ANSYS M h i l


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November 2010

Customer Training Material Spot Weld

Spot welds provide a means of connecting assemblies at discrete points:

Spot weld is defined in the CAD software. Currently, only DesignModeler and

Unigraphics define spot welds supported by Mechanical.

Spot weld pairs

I t d ti t ANSYS M h i l


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November 2010

Customer Training Material Contact Worksheet

The Worksheet for the Connections branch provides a summary of

various contact and spot weld definitions:



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November 2010

Customer Training MaterialC. Coordinate Systems

The Coordinate Systems branch initially contains only the global Cartesian

system.

Coordinate systems can be used for mesh controls, point masses,directional loads, and results.

Local Coordinate Systems can be created or imported from some CAD systems

(see Mechanical documentation).



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November 2010

Customer Training Material Coordinate Systems

Coordinate Systems (Cartesian or cylindrical) can be

defined by selecting Coordinate System icon from the

Context toolbar. The CS toolbar becomes available after CS is defined.

Local coordinate systems are defined either by:

Selecting geometry (Associative Coordinate System). The

coordinate system updates if the geometrys location is

updated (not during solution). Its translation and rotation

are geometry dependent.

Specifying coordinates (Non-Associative Coordinate

System). The coordinate system will remain as originally

defined i.e.: it is independent of geometry.

Translate Rotate Flip Move Up/Down

Delete



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November 2010

Customer Training Material Coordinate Systems

Coordinate systems can be used from pull-down menus in the Details

view in various applications (examples below) :

Sizing w/ Sphere of

Influence Option

Directional ResultsPoint Masses

Directional Loads

Directional Displacements



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November 2010

Customer Training MaterialD. Named Selections

The Named Select ion Toolb arprovides functionality for grouping together

geometric entities:

Named Selections allow users to group together vertices, edges, surfaces, or

bodies.

Named Selections can be used for defining mesh controls, applying loads and

supports, etc.

Provides an easy method to reselect groups that will be referenced often

Defining contact regions

Scoping results

Etc.

Create Defined Names

Manipulate Show/Hide Suppress/Unsuppress



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November 2010

Customer Training Material Defining Named Selections

To create Selections using geometry selection:

Select the vertices, edges, surfaces, or bodies of interest,

then click on the Create Selection Group icon. Enter a name in the dialog box.

The new group will appear in the Named Selection

Toolbar as well as in the Outline Tree.

Note:

Only one type of entity can be in a particular

Named Selection. For example, vertices and

edges cannot exist in the same Named Selection.

Named Selection groups can be imported from

some CAD systems (see Chapter 10).



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November 2010


Selections can be created employing various criteria using the

Worksheet method.

Add, remove, filter, etc. to stack criteria for complex selections.

Each selection is generated to complete the operation.



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November 2010


Example, select a vertex at x,y,z = 97.7, 33, 0:

Using three operations (add, filter, remove),

allows a single vertex selection.

Results in 4 vertices selected

Results in 2 vertices selected

Results in 1 vertex selected



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November 2010

Customer Training Material Using Named Selections

In many detail window fields Named Selections can be referenced

directly:

Example (pressure load):

In the Details view, change Method from Geometry Selection to Named

Selection

Select the Named Selection from the pull-down menu

Mechanical will filter non-applicable types of Named Selections.



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November 2010

Customer Training Material Using Named Selections

Named Selections can be used in other situations where geometry must

be picked:

Select Geometry from the Details view to enter picking mode

Toggle the Named Selection to select from the Toolbar

Select the applicable choice:

Select Items in Group, Add to Current Selection, Remove from Current Selection

Then, click on Apply in the Details view

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Customer Training Material

Workshop 3.1Contact Control

Goal:

Investigate several types of contact behavior.

E. Workshop 3.1Contact Control
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