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Chapter 1
Introduction
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Introduction to ANSYS 7.1 - Part 1
Table of Contents
8. Loading1. Introduction
2. FEA and ANSYS
3. ANSYS Basics
4. General Analysis Procedure
5. Creating the Solid Model
6. Creating the Finite Element Model
7. Defining the Material
9. Solution
10. Structural Analysis
11. Thermal Analysis
12. Coupled-field Analysis
13. Postprocessing
14. Short Topics
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Chapter 2
FEA and ANSYS
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Chapter 2 - FEA and ANSYS
What is FEA?
Finite Element Analysisis a way to simulate loading conditions ona design and determine the designs response to thoseconditions.
The design is modeled using discrete building blocks calledelements.
Each element has exact equations
that describe how it responds to acertain load.
The sum of the response of allelements in the model gives thetotal response of the design.
The elements have a finite numberof unknowns, hence the namefinite elements.
Historical Note
The finite element method ofstructural analysis was createdby academic and industrialresearchers during the 1950sand 1960s.
The underlying theory is over100 years old, and was the basisfor pen-and-paper calculationsin the evaluation of suspensionbridges and steam boilers.
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Chapter 2 - FEA and ANSYS
...What is FEA?
The finite element model, which has a finitenumber of unknowns,can only approximatethe response of the physical system, whichhas infiniteunknowns.
So the question arises: How good is the approximation?
Unfortunately, there is no easyanswer to this question. It dependsentirely on what you are simulating
and the tools you use for thesimulation. We will, however,attempt to give you guidelinesthroughout this training course.
Physical System F.E. Model
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Chapter 2 - FEA and ANSYS
...What is FEA?
Why is FEA needed?
To reduce the amount of prototype testing
Computer simulation allows multiple what-if scenarios to be testedquickly and effectively.
To simulate designs that are not suitable for prototype testing
Example: Surgical implants, such as an artificial knee
The bottom line:
Cost savings
Time savings reduce time to market!
Create more reliable, better-quality designs
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Chapter 2 - FEA and ANSYS
About ANSYS
ANSYS is a complete FEA software package used by engineersworldwide in virtually all fields of engineering:
Structural
Thermal Fluid (CFD, Acoustics, and other fluid analyses)
Low- and High-Frequency Electromagnetics
A partial list of industries in which ANSYS is used:
Aerospace
Automotive
Biomedical
Bridges & Buildings
Electronics & Appliances
Heavy Equipment & Machinery
MEMS - Micro Electromechanical Systems
Sporting Goods
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Chapter 2 - FEA and ANSYS
About ANSYS
Structural analysis is used to determine deformations, strains,stresses, and reaction forces.
Static analysis
Used for static loadingconditions.
Nonlinear behavior suchas large deflections, largestrain, contact, plasticity,hyperelasticity, and creepcan be simulated.
Compression of a Hyperelastic Seal
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Chapter 2 - FEA and ANSYS
About ANSYS
Dynamic analysis
Includes mass and dampingeffects.
Modal analysis calculates natural
frequencies and mode shapes. Harmonic analysis determines a
structures response tosinusoidal loads of knownamplitude and frequency.
Transient Dynamic analysisdetermines a structuresresponse to time-varying loadsand can include nonlinearbehavior.
Other structural capabilities Spectrum analysis
Random vibrations
Eigenvalue buckling
Substructuring, submodeling
Mode Shape Animation
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Chapter 2 - FEA and ANSYS
About ANSYS
Explicit Dynamics with ANSYS/LS-DYNA
Intended for very large deformation simulations where inertia forcesare dominant.
Used to simulate impact, crushing, rapid forming, etc.
Impact Analysis of a Vehicle Crash Test
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Chapter 2 - FEA and ANSYS
About ANSYS
Thermal analysis is used to determine the temperaturedistribution in an object. Other quantities of interest includeamount of heat lost or gained, thermal gradients, and thermal flux.
All three primary heat transfer modes can be simulated:conduction, convection, radiation.
Steady-State Time-dependent effects are
ignored.
Transient To determine temperatures, etc.as a function of time.
Allows phase change (melting orfreezing) to be simulated.
Transient Temperature of aWarming Clothes Iron
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Chapter 2 - FEA and ANSYS
About ANSYS
Electromagnetic analysis is used to calculate magnetic fields inelectromagnetic devices.
Static and low-frequency electromagnetics
To simulate devices operating with DC power sources, low-frequencyAC, or low-frequency transient signals.
Example: solenoid actuators,
motors, transformers Quantities of interest include
magnetic flux density, fieldintensity, magnetic forces andtorques, impedance, inductance,
eddy currents, power loss, andflux leakage.
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Chapter 2 - FEA and ANSYS
About ANSYS
High-frequency electromagnetics
To simulate devices with propagating electromagnetic waves.
Example: microwave and RF passive components, waveguides,coaxial connectors
Quantities of interest include S-parameters, Q-factor, Return loss,dielectric and conducting losses, and electric and magnetic fields.
Electric field (EFSUM) in a coaxial cable
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Chapter 2 - FEA and ANSYS
About ANSYS
Electrostatics
To calculate the electric field from voltage or charge excitation.
Example: High voltage devices, micro-electromechanical systems(MEMS), transmission lines
Typical quantities of interest are electric field strength andcapacitance.
Current Conduction
To calculate current in a conductor from an applied voltage
Circuit Coupling
To couple electric circuits with electromagnetic devices
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Chapter 2 - FEA and ANSYS
About ANSYS
Types of electromagnetic analysis:
Static analysis calculates magnetic fields due to direct current (DC) orpermanent magnets.
Harmonic analysis calculates magnetic fields due to alternatingcurrent (AC).
Transient analysis is used for time-varying magnetic fields.
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Chapter 2 - FEA and ANSYS
About ANSYS
Computational Fluid Dynamics(CFD)
To determine the flowdistributions and temperatures in
a fluid. ANSYS/FLOTRAN can simulate
laminar and turbulent flow,compressible and incompressibleflow, and multiple species.
Applications: aerospace,electronic packaging, automotivedesign
Typical quantities of interest arevelocities, pressures,temperatures, and film
coefficients.
Velocity of Fluid in a Duct Pressure Distributionon a Football
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Chapter 2 - FEA and ANSYS
About ANSYS
Acoustics
To simulate the interaction between a fluid medium and the surroundingsolid.
Example: speakers, automobile interiors, sonars
Typical quantities of interest are pressure distribution, displacements,and natural frequencies.
Contained-Fluid Analysis
To simulate the effects of a contained, non-flowing fluid and calculatehydrostatic pressures due to sloshing.
Example: oil tankers, other liquid containers
Heat and Mass Transport
A one-dimensional element is used to calculate the heat generated bymass transport between two points, such as in a pipe.
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Chapter 3
ANSYS Basics
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Output
Window
Icon Toolbar Menu
Abbreviation Toolbar Menu
Utility Menu
Graphics AreaMain Menu
Input Line
Chapter 3 The GUI
Layout
Current Settings
Raise/Hidden Icon
User Prompt Info
Command Window Icon
Model ControlToolbar
C G
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Chapter 3 The GUI
Main Menu
Tree structure format.
Contains the main functions required for ananalysis.
Use scroll bar to gain access to long treestructures.
Colors used to show tree level.
scroll bar
Chapter 3 The GUI
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Chapter 3 The GUI
Main Menu
Tree structure behavior sub branch preserved
Before collapsing Preprocessor Branch After expanding Preprocessor Branch
The tree structure is the same before
and after the Preprocessor branch ofMain Menu is collapsed
Select to collapse
Preprocessor Branch
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Chapter 3 The GUI
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Chapter 3 The GUI
Abbreviation Toolbar Menu
Contains abbreviations-- short-cuts to commonly usedcommands and functions.
A few predefined abbreviations are available, but you can add
your own. Requires knowledge of ANSYS commands.
A powerful feature which you can use to create your own buttonmenu system!
Chapter 3 The GUI
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Chapter 3 The GUI
Icon Toolbar Menu
Contains iconsof commonly used functions.
Can be customized by the user (i.e adding icons, additional
toolbars)
Pan-Zoom-Rotate
New Analysis
Open ANSYS File
Save Analysis
ANSYS Help
Image Capture
Report Generator
Chapter 3 The GUI
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Chapter 3 The GUI
.Icon Toolbar Menu
Jobname definition when using Open ANSYS File Icon:
the ANSYS jobname will be changed to the prefix of the database file being resumed.
Open ANSYS
File
When opening the blades.db database(using the Open ANSYS File Icon), the
jobname will be changed to blades.
The Open ANSYS File Icon can be used to open either ANSYS
Database or ANSYS Command file types
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Chapter 3 The GUI
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Chapter 3 The GUI
Input Window
Allows you to enter commands. (Most GUI functions actuallysend commands to ANSYS. If you know these commands, youcan type them in the Input Window).
As a command is typed, the format of the command isdynamically displayed.
Click on theX to returnthe input tothe toolbar.
Clicking on the ANSYSCommand Window Iconmoves the input line to aseparate commandwindow, which can bemoved around the screen.
Chapter 3 The GUI
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Chapter 3 The GUI
Utility Menu
Contains utilities that are generally available throughout theANSYS session: graphics, on-line help, select logic, file controls,etc.
Conventions used in Utility Menu:
indicates a dialog box
+ indicates graphical picking
> indicates a submenu
(blank) indicates an action
Chapter 3 The GUI
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Chapter 3 The GUI
Current Settings
The current element attributes settings, and currently activecoordinate system are displayed at the bottom on the GUI.
Element Attributes Active Coordinate System
Chapter 3 The GUI
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C apte 3 e GU
User prompt info
Instructions to the user are displayed in the lower left hand area ofthe GUI. The user will be given user prompt info for operationssuch as picking operations.
User Prompt Info
Chapter 3 The GUI
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Preferences
The Preferences dialog (Main Menu >Preferences) allows you to filter outmenu choices that are not applicable tothe current analysis.
For example, if you are doing a thermalanalysis, you can choose to filter outother disciplines, thereby reducing thenumber of menu items available in the
GUI: Only thermal element types will be shown
in the element type selection dialog.
Only thermal loads will be shown.
Etc.
Chapter 3 - Interactive Mode
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Graphics and Picking
A Dynamic Mode setting is alsoavailable using Pan-Zoom-Rotate .
The same mouse button assignmentsapply.
On 3-D graphics devices, you can alsodynamically orient the light source.Useful for different light source shadingeffects.
When using 3-D driver
Chapter 3 - Interactive Mode
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Training ManualGraphics and Picking
Other functions in the Pan-Zoom-Rotate dialog box:
Preset views
Zoom-in on specific regions ofthe model
Pan, zoom, or rotate indiscrete increments (asspecified by the Rate slider)
Rotation is about thescreen X, Y, Z coordinates.
Fit the plot to the window
Reset everything to default
The majority of these optionsare available in the ModelControl Toolbar.
Front +Z view, from (0,0,1)
Back -Z view (0,0,-1)
Top +Y view (0,1,0)
Bot -Y view (0,-1,0)
Right +X view (1,0,0)Left -X view (-1,0,0)
Iso Isometric (1,1,1)
Obliq Oblique (1,2,3)
WP Working plane view
Zoom By picking center of asquare
Box Zoom By picking twocorners of a box
Win Zoom Same as Box Zoom,
but box is proportionalto window.
Back Up Unzoom to previouszoom.
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Training ManualThe Database and Files
Save and Resume
Since the database is stored in the computers memory (RAM), itis good practice to saveit to disk frequently so that you can
restore the information in the event of a computer crash or powerfailure.
The SAVE operation copies the database from memory to a file
called the database file(or db filefor short). The easiest way to do a save is to click on Toolbar > SAVE_DB
Or use:
Utility Menu > File > Save as Jobname.db
Utility Menu > File > Save as SAVE command
Chapter 3 - Interactive Mode
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Training ManualThe Database and Files
To restore the database from the db file back into memory, use theRESUME operation.
Toolbar > RESUME_DB
Or use:
Utility Menu > File > Resume Jobname.db
Utility Menu > File > Resume from
RESUME command
The default file name for SAVE and RESUME isjobname.db, butyou can choose a different name by using the Save as orResume from functions.
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Training ManualExiting ANSYS
Three ways to exit ANSYS:
Toolbar > QUIT
Utility Menu > File > Exit
Use the /EXIT command in the Input Window
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Chapter 4
General Analysis Procedure
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Chapter 4 - General Analysis Procedure
O i
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Training ManualOverview
Preprocessing
Solution
Postprocessing
PreliminaryDecisions
Every analysis involves four main steps:
Preliminary Decisions
Which analysis type?
What to model? Which element type?
Preprocessing
Define Material
Create or import the model geometry Mesh the geometry
Solution
Apply loads
Solve
Postprocessing
Review results
Check the validity of the solution
Chapter 4 - A. Preliminary Decisions
Whi h l i t ?
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Training ManualWhich analysis type?
The analysis type usually belongs to one of the followingdisciplines:
Structural Motion of solid bodies, pressure on solid bodies, orcontact of solid bodies
Thermal Applied heat, high temperatures, or changes intemperature
Electromagnetic Devices subjected to electric currents (AC or DC),electromagnetic waves, and voltage or charge
excitationFluid Motion of gases/fluids, or contained gases/fluids
Coupled-Field Combinations of any of the above
The appropriate analysis type for this model is a structural analysis!
Chapter 4 - A. Preliminary Decisions
Wh t t d l?
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Training ManualWhat to model?
What should be used to model the geometry of the spherical tank?
Axisymmetrysince the loading, material, and the boundaryconditions are symmetric. This type of model would provide themost simplified model.
Rotational symmetrysince the loading, material, and theboundary conditions are symmetric. Advantage overaxisymmetry: offers some results away from applied boundaryconditions.
Full 3D modelis an option, but would not be an efficient choicecompared to the axisymmetric and quarter symmetry models. Ifmodel results are significantly influenced by symmetricboundary conditions, this may be the only option.
An axisymmetric and a one-quarter symmetry (i.e. rotationalsymmetry) model will be analyzed for this model!
Chapter 4 - A. Preliminary Decisions
Which Element Type?
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Training ManualWhich Element Type?
What element type should be used for the model of the sphericaltank?
Axisymmetric model:
Axisymmetric since 2-D section can be revolved to created 3D
geometry.
Linear due to small displacement assumption.
PLANE42 with KEYOPT(3) = 1
Rotational symmetry model:
Shell since radius/thickness ratio > 10
Linear due to small displacement assumption.
membrane stiffness only option since membrane stresses arerequired.
SHELL63 with KEYOPT(1) = 1
Since the meshing of this geometry will create SHELL63 elementswith shape warnings, a mid-side noded equation of the SHELL63 wasused:
SHELL93
Chapter 4 - B. Preprocessing
Create the Solid Model
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Training ManualCreate the Solid Model
A typical solid model is defined by volumes, areas, lines, andkeypoints.
Volumesare bounded by areas. They represent solid objects.
Areasare bounded by lines. They represent faces of solid objects, or
planar or shell objects.
Linesare bounded by keypoints. They represent edges of objects.
Keypointsare locations in 3-D space. They represent vertices ofobjects.
Volumes Lines & KeypointsAreas
Chapter 4 - B. Preprocessing
Create the Solid Model
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One-quarter Symmetry ModelAxisymmetric model
What geometry should be used to model the spherical tank?
Chapter 4 - B. Preprocessing
Create the FEA Model
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Training ManualCreate the FEA Model
Meshingis the process used to fill the solid model with nodesand elements, i.e, to create the FEA model.
Remember, you need nodes and elements for the finite elementsolution, not just the solid model. The solid model does NOT
participate in the finite element solution.
Solid model FEA model
meshing
Chapter 4 - B. Preprocessing
Create the FEA Model
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Training ManualCreate the FEA Model
What would the mesh of the spherical tank look like?
One-quarter Symmetry ModelAxisymmetric model
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T i i M l
Chapter 4 C. Solution
Define Loads
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Training ManualDefine Loads
There are five categories of loads:
DOF Constraints Specified DOF values, such as displacementsin a stress analysis or temperatures in athermal analysis.
Concentrated Loads Point loads, such as forces or heat flow rates.Surface Loads Loads distributed over a surface, such as
pressures or convections.
Body Loads Volumetric or field loads, such as temperatures(causing thermal expansion) or internal heatgeneration.
Inertia Loads Loads due to structural mass or inertia, suchas gravity and rotational velocity.
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Chapter 4 C. Solution
Define Loads
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One-quarter Symmetry ModelAxisymmetric model
Edge Symmetryconstraint
Edge Symmetryconstraint Tangential
Constraint*
Hydrostaticpressure
Hydrostaticpressure
TangentialConstraint*
Edge Symmetryconstraint
Define Loads
What are the loads on the spherical tank models?
* Tangential constraint used to allow comparison to Roarke closed form solution.
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Chapter 4 - D. Postprocessing
Review Results
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Training ManualReview Results
Postprocessing is the final step in the finite element analysisprocess.
It is imperative that you interpret your results relative to the
assumptions made during model creation and solution.
You may be required to make design decisions based on theresults, so it is a good idea not only to review the results carefully,
but also to check the validity of the solution.
ANSYS has two postprocessors:
POST1, the General Postprocessor, to review a single set of resultsover the entire model.
POST26, the Time-History Postprocessor, to review results at selectedpoints in the model over time. Mainly used for transient and nonlinearanalyses. (Not discussed in this course.)
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Chapter 4 - D. Postprocessing
Review Results
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Axisymmetric model
What are the meridional stress results in the spherical tankmodels?
One-quarter Symmetry Model
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Chapter 6 Creating the Finite Element Model
Overview
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Meshingis the process used to fill the solid model with nodesand elements, i.e, to create the FEA model.
Remember, you need nodes and elements for the finite elementsolution, not just the solid model. The solid model does NOT
participate in the finite element solution.
Solid model FEA model
meshing
Training Manual
Chapter 6 Creating the Finite Element Model
Element Attributes
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There are three steps to meshing:
Define element attributes
Specify mesh controls
Generate the mesh
Element attributesare characteristics of the finite element modelthat you must establish prior to meshing. They include:
Element types Real constants
Material properties
Section properties (for BEAM44,188, and 189, SHELL181, and PRETS179)
Training Manual
Chapter 6 Creating the Finite Element Model
Element Attributes
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Element Type
The element type is an important choice that determines thefollowing element characteristics:
Degree of Freedom (DOF) set. A thermal element type, for example,has one dof: TEMP, whereas a structural element type may have up tosix dof: UX, UY, UZ, ROTX, ROTY, ROTZ.
Element shape -- brick, tetrahedron, quadrilateral, triangle, etc.
Dimensionality -- 2-D (X-Y plane only), or 3-D. Assumed displacement shape -- linear vs. quadratic.
ANSYS has a library of over 150 element types from which youcan choose. Details on how to choose the correct element type
will be presented later. For now, lets see how to define anelement type.
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Element category
ANSYS offers many different categories of elements. Some of thecommonly used ones are:
Line elements Shells
2-D solids
3-D solids
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Line elements:
Beamelements are used to model bolts, tubular members, C-sections,angle irons, or any long, slender members where only membrane andbending stresses are needed.
Linkelements are used to model springs, bolts, preloaded bolts, andtruss members.
Spring (combination)elements are used to model springs, bolts, orlong slender parts, or to replace complex parts by an equivalentstiffness.
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Shell elements:
Used to model thin panels or curved surfaces.
The definition of thin depends on the application, but as a generalguideline, the major dimensions of the shell structure (panel) should
be at least 10 times its thickness.
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2-D Solid elements:
Used to model a cross-section of solid objects.
Must be modeled in the global Cartesian X-Y plane.
All loads are in the X-Y plane, and the response (displacements) are
also in the X-Y plane. Element behavior may be one of the following:
plane stress
plane strain
generalized plain strain
axisymmetric
axisymmetric harmonic
Y
XZ
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Plane stressassumes zero stress inthe Z direction.
Valid for components in which the Zdimension is smaller than the X and Y
dimensions. Z-strain is non-zero.
Optional thickness (Z direction)allowed.
Used for structures such as flat platessubjected to in-plane loading, or thindisks under pressure or centrifugalloading.
Y
XZ
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Plane strainassumes zero strain in the Zdirection.
Valid for components in which the Z dimension ismuch larger than the X and Y dimensions.
Z-stress is non-zero. Used for long, constant cross-section structures
such as structural beams.
YX
Z
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Axisymmetryassumes that the 3-D model anditsloading can be generated by revolving a 2-Dsection 360 about the Y axis.
Axis of symmetry must coincide with the global Y
axis. Negative X coordinates are not permitted.
Y direction is axial, X direction is radial, and Zdirection is circumferential (hoop) direction.
Hoop displacement is zero; hoop strains andstresses are usually very significant.
Used for pressure vessels, straight pipes, shafts,etc.
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3-D Solid elements: Used for structures which, because of geometry, materials, loading, or
detail of required results, cannot be modeled with simpler elements.
Also used when the model geometry is transferred from a 3-D CAD
system, and a large amount of time and effort is required to convert itto a 2-D or shell form.
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To define an element type: Main Menu > Preprocessor >
Element Type > Add/Edit/Delete
[Add] to add new element type
Choose the desired type(such as SOLID92) and pressOK
[Options] to specify additional
element options Or use the ET command:
et,1,solid92
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To define real constants: Main Menu > Preprocessor > Real
Constants
[Add] to add a new real constant
set. If multiple element types have
been defined, choose the elementtype for which you are specifyingreal constants.
Then enter the real constantvalues.
Or use the R family of commands.
Different element types requiredifferent real constants. Check theElements Manual, available on-line,for details.
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To define section properties: Main Menu > Preprocessor > Sections
Ability to Import Sections
Beam, Shell and Pretension sections can
be created. Or use the SECxxx family of commands.
Different element types require different
section properties. See the ElementsManualfor details.
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Material Properties
Every analysis requires somematerial property input: Youngsmodulus EX for structural elements, thermal conductivity KXX for
thermal elements, etc.
Refer to Chapter 7 for details on the two ways to define materialproperties.
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Most FEA models have multiple attributes. For example, the silo shownhere has two element types, three real constant sets, and two materials.
MAT 1 = concreteMAT 2 = steel
REAL 1 = 3/8 thicknessREAL 2 = beam propertiesREAL 3 = 1/8 thickness
TYPE 1 = shellTYPE 2 = beam
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Assigning Attributes to the Solid Model
1. Define all necessary element types, materials, andreal constant sets.
2. Then use the Element Attributes section of theMeshTool (Main Menu > Preprocessor > MeshTool):
Choose entity type and press the SET button.
Pick the entities to which you want to assignattributes.
Set the appropriate attributes in the subsequentdialog box.
Or select the desired entities and use the VATT,AATT, LATT, or KATT command.
3. When you mesh an entity, its attributes areautomatically transferred to the elements.
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Using Global Attribute Settings
1. Define all necessary element types,materials, real constant sets and sectionnumbers
2. Then use the Element Attributes sectionof the MeshTool (Main Menu > Preprocessor> MeshTool):
Choose Global and press the SET button.
Activate the desired combination of attributesin the Meshing Attributes dialog box. Werefer to these as the activeTYPE, REAL, MATand SECNUM settings.
Or use the TYPE, REAL, MAT and SECNUMcommands.
3. Mesh only those entities to which the abovesettings apply.
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ANSYS provides many tools to control mesh density, both on aglobal and local level:
Global controls
SmartSizing
Global element sizing
Default sizing
Local controls
Keypoint sizing
Line sizing
Area sizing
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SmartSizing
Determines element sizes by assigning divisions on all lines,taking into account curvature of the line, its proximity to holes and
other features, and element order.
SmartSizing is off by default, but is recommended for freemeshing. It does not affect mapped meshing. (Free meshing vs.mapped meshing will be discussed later.)
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To use SmartSizing: Bring up the MeshTool (Main Menu > Preprocessor >
Meshing > MeshTool), turn on SmartSizing, and set thedesired size level.
Or use SMRT,level Size level ranges from 1 (very fine) to 10 (very
coarse). Defaults to 6.
Then mesh all volumes (or all areas) at once, rather thanone-by-one.
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Examples of different SmartSizelevels are shown here for atetrahedron mesh.
Advanced SmartSize controls, such
as mesh expansion and transitionfactors, are available on the SMRTcommand or:
Main Menu > Preprocessor > Meshing >Size Cntrls > SmartSize > Adv Opts
You can turn off SmartSizing usingthe MeshTool or by issuing smrt,off.
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Global Element Sizing
Allows you to specify a maximum element edge lengthfor the entire model (or number of divisions per line): ESIZE,SIZE
or Main Menu > Preprocessor > Meshing > MeshTool; thenselect Size Controls, Global ,and [Set]
or Main Menu > Preprocessor > Meshing > Size Cntrls >ManualSize > Global > Size
Can be used by itself or in conjunction with
SmartSizing. Using ESIZE by itself (SmartSizing off) will
result in a uniform element size throughout thevolume (or area) being meshed.
With SmartSizing on, ESIZE acts as a guide,
but the specified size may be overridden toaccommodate line curvature or proximity tofeatures.
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Default Sizing
If you dont specify any controls, ANSYS uses default sizing, whichassigns minimum and maximum line divisions, aspect ratio, etc. based
on element order.
Meant for mapped meshing, but is also used for free meshing ifSmartSizing is off.
You can adjust default size specifications using DESIZE or
Main Menu > Preprocessor > Meshing > Size Cntrls > ManualSize > Global > Other
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Keypoint Sizing
Controls element size at keypoints:
Main Menu > Preprocessor > Meshing > MeshTool; then
select Size Controls, Keypt, and [Set] or KESIZE command
or Main Menu > Preprocessor > Meshing > Size Cntrls >ManualSize > Keypoints
Different keypoints can have different KESIZEs, givingyou more control over the mesh.
Useful for stress concentration regions.
Specified sizes may be overridden by SmartSizing toaccommodate line curvature or proximity to features.
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Line Sizing
Controls element size at lines:
Main Menu > Preprocessor > Meshing > MeshTool;then select Size Controls, Lines, and [Set]
or LESIZE command or Main Menu > Preprocessor > Meshing > Size Cntrls
> ManualSize> Lines
Different lines can have different LESIZEs.
Size specifications may be hard or soft. Hard sizes are always honored by the mesher, even if
SmartSizing is on. They take precedence over all othersize controls.
Soft sizes may be overridden by SmartSizing.
You can also specify a spacing ratio ratio of lastdivision to first. Used to bias the divisions towards oneend or towards the middle.
Yes for softNo for hard
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Area Sizing
Controls element size in the interior of areas:
Main Menu > Preprocessor > Meshing > MeshTool; then
select Size Controls, Areas, and [Set] or AESIZE command
or Main Menu > Preprocessor > Meshing > Size Cntrls >ManualSize > Areas
Different areas can have different AESIZEs.
Bounding lines will use the specified size only if theyhave no LESIZE or KESIZE specified and if no
adjacent area has a smaller size.
Specified sizes may be overridden by SmartSizing toaccommodate line curvature or proximity to features.
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By default, ANSYS will mesh areas or volumes in ascending entitynumber.
The AORDER field on the MOPT command instructs ANSYS to mesh a
group of areas or volumes in order of ascending size. Main Menu > Preprocessor > Meshing > Mesher Opts , or
MOPT,AORDER,ON (default is OFF)
In cases where SmartSizing does not mesh as fine as needed,the MOPT, AORDER,on command generates finer meshes incritical areas for volume meshes
This option is not available when SmartSizing is on.
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Generating the meshis the final step in meshing.
First save the database.
Then press [Mesh] in the MeshTool. This brings up a picker. Press [Pick All] in the pickerto indicate all entities.
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Demo: Resume ribgeom.db
Mesh with SMRT,6. (Not a very good mesh)
Re-mesh with SMRT,3 (good mesh)
Set ESIZE to 0.2 and re-mesh. The mesh becomes coarse even thoughSMRT is set to 3, because the smart-mesher takes ESIZE into account.Also, note that the element sizes are not uniform (because SMRT ison).
Turn off SMRT and re-mesh. Element sizes are now more uniform (but
not ideal).
Re-mesh with ESIZE set to 0.1.
Good meshes generated for this geometry with SMRT,3 or ESIZE,0.1.
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If a mesh is not acceptable, you can alwaysre-mesh the model by following these steps:
1. Clear the mesh.
The clearoperation is the opposite of mesh: it
removes nodes and elements. Use the [Clear] button on the MeshTool, or use
VCLEAR, ACLEAR, etc.
(If you are using the MeshTool, you may skip thisstep since the program will prompt you whether toclear or not when you execute step 3.)
2. Specify new or different mesh controls.
3. Mesh again.
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Another meshing option is to refinethemesh in specific regions.
Available for all area elements and onlytetrahedral volume elements.
Easiest way is to use the MeshTool:
First save the database.
Then choose how you want tospecify the region of refinement atnodes, elements, keypoints, lines, orareas and press the Refine button.
Pick the entities at which you wantthe mesh to be refined. (Not requiredif you choose All Elems.)
Finally, choose the level ofrefinement. Level 1 (minimal
refinement) is a good starting point.
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Demo: Continuing the last demo (ribgeom has been meshed with ESIZE =
0.2)
Choose refinement at Lines and press Refine
Pick the top line, then choose the default minimal refinement
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There are two main meshing methods: freeandmapped.
Free Mesh
Has no element shape restrictions. The mesh does not follow any pattern.
Suitable for complex shaped areas and volumes.
Mapped Mesh
Restricts element shapes to quadrilaterals for areasand hexahedra (bricks) for volumes.
Typically has a regular pattern with obvious rows ofelements.
Suitable only for regular areas and volumes such asrectangles and bricks.
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Free Mesh
+ Easy to create; no need to dividecomplex shapes into regularshapes.
Volume meshes can contain onlytetrahedra, resulting in a largenumber of elements.
Only higher-order (10-node)tetrahedral elements areacceptable, so the number ofDOF can be very high.
Mapped Mesh
+ Generally contains a lowernumber of elements.
+ Lower-order elements may beacceptable, so the number ofDOF is lower.
Areas and volumes must be
regular in shape, and meshdivisions must meet certaincriteria.
Very difficult to achieve,
especially for complex shapedvolumes.
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Creating a Mapped Mesh
This is not as easy as free meshing because the areas andvolumes have to meet certain requirements:
Area must contain either 3 or 4 lines (triangle or quadrilateral). Volume must contain either 4, 5, or 6 areas (tetrahedron, triangular
prism, or hexahedron).
Element divisions on opposite sides must match.
For triangular areas or tetrahedral volumes, the number of elementdivisions must be even.
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Thus mapped meshing involves a three-step procedure:
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Thus mapped meshing involves a three step procedure: Ensure regular shapes, i.e, areas with 3 or 4 sides, or volumes with
4, 5, or 6 sides.
Specify size and shape controls
Generate the mesh
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Ensure regular shapes
In most cases, the model geometry is such that the areas havemore than 4 sides, and volumes have more that 6 sides. Toconvert these to regular shapes, you may need to do one or bothof these operations:
Slice the areas (or volumes) into smaller, simpler shapes.
Concatenate two or more lines (or areas) to reduce the total number ofsides.
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Slicing can be accomplished with the Boolean divide operation.
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Slicingcan be accomplished with the Boolean divideoperation. Remember that you can use the working plane, an area, or a line as
the slicing tool.
Sometimes, it may be easier to createa new line or a new area than tomove and orient the working plane in the correct direction.
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Concatenation creates a new line (for meshing purposes) that is abi ti f t li th b d i th b f
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Concatenationcreates a new line (for meshing purposes) that is acombination of two or more lines, thereby reducing the number oflines making up the area.
Use the LCCAT command or Main Menu > Preprocessor > Meshing >Concatenate > Lines, then pick the lines to be concatenated.
For area concatenation, use ACCAT command or Main Menu >Preprocessor > Meshing > Concatenate > Areas
Concatenatingthese two linesmakes this a4-sided area
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You can also imply a concatenation by simplyidentifying the three or four corners of the area In this
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p y y p yidentifying the three or four corners of the area. In thiscase, ANSYS internally generates the concatenation.
To do this, choose Quad shape and Map mesh in theMeshTool.
Then change 3/4 sided to Pick corners. Press the Mesh button, pick the area, and then pick the 3 or
4 corners that form the regular shape.
INTRINTRINTRINTR
Training Manual
Chapter 6 Creating the Finite Element Model
Mapped Meshing
Notes on concatenation:It is purely a meshing operation and therefore should be the last step before
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It is purely a meshing operation and therefore should be the last step beforemeshing, after all solid modeling operations. This is because the output entityobtained from a concatenation cannot be used in any subsequent solid modelingoperation.
You can "undo" a concatenation by deleting the line or area it produced. Concatenating areas (for mapped volume meshing) is generally much more
complicated because you may also need to concatenate some lines. Lines areautomatically concatenated only when two adjacent, 4-sided areas areconcatenated.
Consider the add(Boolean) operation if the lines or areas meet at a tangent.
INTRINTRINTRINTR
Training Manual
Chapter 6 Creating the Finite Element Model
Mapped Meshing
Specify size and shape controls Meshing Areas:
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This is the second step of the three-step mappedmeshing procedure.
Choosing the shape is simple. In the MeshTool, chooseQuad for area meshing, and Hex for volume meshing,then click on Map.
Commonly used size controls and the order in which
they are applied: Line sizing [LESIZE] is always honored.
Global element size , if specified, will be applied to unsizedlines.
Default element sizing [DESIZE] will be applied to unsized
lines only if ESIZE is not specified. (SmartSizing is not valid.)
Meshing Volumes:
INTRINTRINTRINTR
Training Manual
Chapter 6 Creating the Finite Element Model
Mapped Meshing
If you specify line divisions, remember that:divisions on opposite sides must match but you only need to specify
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divisions on opposite sides must match, but you only need to specifyone side. The map mesher automatically transfers divisions to theopposite side.
if you have concatenated lines, divisions can only be applied to theoriginal (input) lines, not the composite line.
6 divisions specified on
each original line.
12 divisions will beautomatically applied tothis line (opposite tocomposite line).
How many divisions areused for the other twolines? (Upcoming demowill answer it.)
INTRINTRINTRINTR
Training Manual
Chapter 6 Creating the Finite Element Model
Mapped Meshing
Generate the mapped mesh
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Once you have ensured regular shapes and assigned theappropriate divisions, generating the mesh is easy. Just press theMesh button in the MeshTool, then press [Pick All] in the picker orchoose the desired entities.
INTRINTRINTRINTR
Training Manual
Chapter 6 Creating the Finite Element Model
Mapped Meshing
Question: How would youslice this model for
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slice this model formapped meshing?
Answer: It may not be worth theeffort!
INTRINTRINTRINTR
Training Manual
Chapter 6 Creating the Finite Element Model
Mapped Meshing
Demo: Resume ribfull db
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Resume ribfull.db
Bring up MeshTool and apply 6 divisions to top and right lines
Map-mesh the area using Pick corners. Notice that the left andbottom lines get only two divisions each (from DESIZE).
Now specify ESIZE,,4 (4 divisions per line) and re-mesh
Finally, clear line divisions, specify ESIZE,0.1 (size), and re-mesh
INTROINTRINTROINTR
Training Manual
Chapter 6 Creating the Finite Element Model
Hex-to-Tet Meshing
For volume meshing, we have only seen twooptions so far:
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options so far:
Free meshing, which creates an all-tet mesh. Thisis easy to achieve but may not be desirable insome cases because of the large number of
elements and total DOF created.
Mapped meshing, which creates an all-hex mesh.This is desirable but usually very difficult toachieve.
Hex-to-tet meshingprovides a third option thatis the best of both worlds. It allows you tohave a combination of hex and tet mesheswithout compromising the integrity of the mesh.
INTROINTRINTROINTRO
Training Manual
Chapter 6 Creating the Finite Element Model
Hex-to-Tet Meshing
This option works by creating pyramid-shaped elements in the transitionregion between hex and tet regions.
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Requires the hex mesh to be available (or at least a quad mesh at the sharedarea).
The mesher first creates all tets, then combines and rearranges the tet elements
in the transition region to form pyramids. Available only for element types that support both pyramid and tet shapes, e.g:
Structural SOLID95, 186, VISCO89
Thermal SOLID90
Multiphysics SOLID62, 117, 122
SOLID95
Results are good even in the transitionregion. Element faces are compatible evenwhen transitioning from a linear hexelement to a quadratic tet element.
INTROINTRO
INTROINTRO
Training Manual
Chapter 6 Creating the Finite Element Model
Hex-to-Tet Meshing
Hex-to-tet meshing is valid for both quadratic-to-quadratic and linear-to-quadratic transitions. Element type must support a 9-node pyramid for the latter.
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Hex Mesh Transition Layer Tet Mesh
10-Node Tet13-Node Pyramid20-Node Hex
Quadraticto
Quadratic
8-Node Hex 9-Node Pyramid 10-Node Tet
LineartoQuadratic
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INTROINTRO
Training Manual
Chapter 6 Creating the Finite Element Model
Hex-to-Tet Meshing
Procedure involves four steps:
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1. Create the hex mesh.
Start by map-meshing the regular-shaped volumes. (Or mesh theshared areas with quads.)
For stress analysis, use either an 8-node brick (SOLID45 or SOLID185)or a 20-node brick (SOLID95 or SOLID186).
INTROINTRO
INTROINTRO
Training Manual
Chapter 6 Creating the Finite Element Model
Hex-to-Tet Meshing
2. Activate an element type that supports both pyramids and tets. These are usually brick elements that can degenerate into pyramids
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y g pyand tets. Check the Elements Manual, available on-line, to find outwhich element types are valid.
Examples:
Structural SOLID95, 186, VISCO89
Thermal SOLID90
Multiphysics SOLID62, 117, 122
INTROINTRO
INTROINTRO
Training Manual
Chapter 6 Creating the Finite Element Model
Hex-to-Tet Meshing
3. Generate the tet mesh. First activate free meshing.
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Then mesh the volumes that are to be tet-meshed.
Pyramids are automatically generated at the interface.
INTROINTRO
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Training Manual
Chapter 6 Creating the Finite Element Model
Hex-to-Tet Meshing
4. Convert degenerate tets to true 10-node tets. The tet mesh created by the transition mesher consists of degenerate
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elements 10-node tetrahedra derived from 20-node bricks, forexample.
These elements are not as efficient as true 10-node tets such as
SOLID92, which use less memory and write smaller files duringsolution.
To convert the degenerate tets into true tets:
Main Menu > Preprocessor > Meshing > Modify Mesh > Change Tets
Or use the TCHG command.
INTROINTRO
INTROINTRO
Training Manual
Chapter 6 Creating the Finite Element Model
Hex-to-Tet Meshing
Demo: Resume hextet.db
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Show element type list using Element Type > Add/Edit/Delete. Thereare two element types: SOLID45 & 95
Bring up MeshTool and set ESIZE,1 (size)
Map-mesh the regular shaped volume
Set element type to 2, and activate tet-meshing
Free-mesh the other volume
Convert degenerate tets to SOLID92
Show element type list. There are now three element types.
Select elements of type 2 (SOLID95 pyramids) and plot elements
INTROINTRO
INTROINTRO
Training Manual
Chapter 6 Creating the Finite Element Model
Mesh Extrusion
When you extrudean area into a volume, you can extrude the areaelements along with it, resulting in a meshed volume. This is called meshextrusion.
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e t us o
Advantage: Easy to create a volume mesh with all bricks (hexahedra) or acombination of bricks and prisms.
Obvious requirement: Shape of the volume must lend itself to extrusion.
Extrude
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INTROINTRO
INTROINTRO
Training Manual
Chapter 6 Creating the Finite Element Model
Mesh Extrusion
2. Mesh the area to be extruded with MESH200 elements. Use mapped or free meshing with desired mesh density.
Main Menu > Preprocessor > Meshing > MeshTool
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Main Menu > Preprocessor > Meshing > MeshTool
3. Choose element extrusion options.
EXTOPT command or Main Menu >Preprocessor > Modeling > Operate > Extrude> Elem Ext Opts
Typical options are:
Active TYPE attribute (should be 3-Dsolid).
Number of element divisions in theextrusion direction (i.e, number ofelements through the thickness). Mustbe greater than zero; otherwise, onlythe area will be extruded, withoutelements.
INTROD
INTRO
INTROD
INTRO
Training Manual
Chapter 6 Creating the Finite Element Model
Mesh Extrusion
4. Extrude the area. First delete concatenated lines, if any. If concatenations are present,
ANSYS will not allow the extrusion operation
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ANSYS will not allow the extrusion operation.
Main Menu > Preprocessor > Meshing > Concatenate > Del Concats > Lines
Then extrude the area using any of the extrusion methods.
INTROD
INTRO
INTROD
INTROD
Training Manual
Chapter 6 Creating the Finite Element Model
Mesh Extrusion
Demo: Resume ribgeom.db
B i th El t T di l d l t PLANE82 l t t d
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Bring up the Element Types dialog, delete PLANE82 element type, andreplace it with MESH200 4-node quad
Also add SOLID45 as element type 2
Bring up MeshTool and set ESIZE,0.1
Choose free quad-meshing and mesh the area
Set extrusion options: TYPE=2, number of element divisions = 4
Rotate view to ISO
Extrude area along normal with offset = 0.4
Save the database to ribvol.db
INTROD
INTROD
INTROD
INTROD
Training Manual
Chapter 6 Creating the Finite Element Model
Sweep Meshing
Sweep meshing is yet another option available for volumemeshing. It is the process of meshing an existing volume bysweeping an area mesh
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sweeping an area mesh.
Similar to mesh extrusion, except that the volume already exists in
this case (from a geometry import, for example).
INTROD
INTROD
INTROD
INTROD
Training Manual
Chapter 6 Creating the Finite Element Model
Sweep Meshing
Advantages: Easy to create a volume mesh with all
bricks (hexahedra) or a combination
Target surface(1 area)
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bricks (hexahedra) or a combinationof bricks and prisms.
Option to tet-mesh volumes that are
not sweepable. Transitionpyramids are automaticallygenerated.
Requirements:
Topology of the volume must beconsistent in the sweep direction.Example: a block with a through hole(ok even if the hole is tapered).
Sourceand targetsurfaces must besingle areas. Concatenated areas arenot allowed for either the source orthe target.
Source surface(1 area)
Valid for sweep meshing
Not valid for sweep meshing
INTROD
INTROD
INTROD
INTROD
Training Manual
Chapter 6 Creating the Finite Element Model
Sweep Meshing
Procedure
Define and activate a 3-D hexahedral solid element
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type, such as structural SOLID45 or SOLID95.
Bring up MeshTool and choose Hex/Wedge and Sweep.
Choose how the source and target surfaces areidentified:
Auto Source/Target means that ANSYS will automatically
choose them based on the volumes topology. Pick Source/Target means that you will be choosing
them.
Press the SWEEP button and follow prompt
instructions from the picker. (Or use VSWEEPcommand.)
INTROD
INTROD
INTROD
INTROD
Training Manual
Chapter 6 Creating the Finite Element Model
Sweep Meshing
Tet-Mesh Option
A useful sweep option is to generate a tet-
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A useful sweep option is to generate a tetmesh in non-sweepable volumes.
To use this option: Make sure that the element type supports
degenerate pyramid and tetrahedronshapes. Examples:
Structural SOLID95, 186, VISCO89 Thermal SOLID90
Multiphysics SOLID62, 117, 122
Choose Main Menu > Preprocessor > Meshing> Mesh > Volume Sweep > Sweep Opts and
activate the tet-mesh option. (Or use theEXTOPT,VSWE command.)
INTROD
INTROD
INTROD
INTROD
Training Manual
Chapter 6 Creating the Finite Element Model
Sweep Meshing
Notes
To map-mesh a complex volume, you may need to slice it several
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p p , y ytimes and also do some area and line concatenations. For sweepmeshing, you typically need only a few slicing operations, and no
concatenations are needed!
You can control the source area mesh using standard meshcontrols. SmartSizing is generally not recommended since it is
meant for free meshing.
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Chapter 7
Defining the Material
INTROD
INTROD
INTROD
INTROD
Training Manual
Chapter 7 Defining the Material
Material Model GUI
Specifying Individual Material Properties
Instead of choosing a material name, this method involves directlyif i th i d ti th h th M t i l M d l GUI
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specifying the required properties through the Material Model GUI.
To specify individualproperties:
Main Menu > Preprocessor >Material Props > Material Models
Double-click on theappropriate property to bedefined.
INTROD
INTROD
INTROD
INTROD
Training Manual
Chapter 7 Defining the Material
Material Model GUI
Work through the treestructure to the materialtype to be defined.
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Then enter the individual
property values.
Or use the MP command. mp,ex,1,30e6
mp,prxy,1,.3
INTROD
INTROD
INTROD
INTROD
Training Manual
Chapter 7 Defining the Material
Listing Defined Materials
The Material Model GUI shows one material at a time. Multiplematerial properties can be listed by:
Utility Menu > List > Properties > All Materials
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Or, use the MPLIST command
Note, Nonlinear material properties can be listed using Utility Menu >
List Properties > Data Tables or via the TBLIST command.
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Chapter 8
Loading
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INTROD
INTROD
INTROD
INTROD
Training Manual
Chapter 8 - Loading
Define Loads
There are five categories of loads:
DOF Constraints Specified DOF values, such as displacementsin a stress analysis or temperatures in athermal analysis
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thermal analysis.
Concentrated Loads Point loads, such as forces or heat flow rates.
Surface Loads Loads distributed over a surface, such aspressures or convections.
Body Loads Volumetric or field loads, such as temperatures(causing thermal expansion) or internal heatgeneration.
Inertia Loads Loads due to structural mass or inertia, suchas gravity and rotational velocity.
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INTROD
INTROD
INTROD
INTROD
Training Manual
Chapter 8 - Loading
...Nodal Coordinate System
To rotate nodes, use this four-step procedure:
1. Select the desired nodes.
2. Activate the coordinate system (or create a local CS)i t hi h t t t t th d CSYS 1
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into which you want to rotate the nodes, e.g, CSYS,1.
3. Choose Main Menu > Preprocessor > Modeling >
Move/Modify > Rotate Node CS > To Active CS, then press[Pick All] in the picker.
Or issue NROTAT,ALL.
4. Reactivate all nodes.
Note: When you apply symmetry on anti-symmetryboundary conditions, ANSYS automatically rotates allnodes on that boundary.
INTROD
INTROD
INTROD
INTROD
Training Manual
Chapter 8 - Loading
...Nodal Coordinate System
Demo: Resume rib.db.
Offset working plane to center of bottom circle (using average keypoint location).
Create local cylindrical CS at working plane origin
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Create local cylindrical CS at working plane origin.
Select nodes at radius = 0.35 and plot them.
Rotate all selected nodes into active system. Apply a UX displacement constraint (or an FX force) at all selected nodes. Note
the radial direction.
Now activate global Cartesian (CSYS,0).
Rotate all selected nodes into active system.
Replot, and note the new direction of the loads.
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INTROD
INTROD
INTROD
INTROD
Training Manual
Loading & Solution
Concentrated Forces
A force is a concentrated load (orpoint load) that you can apply ata node or keypoint.
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Point loads such as forces are
appropriate for line elementmodels such as beams, spars, andsprings.
In solid and shell models, pointloads usually cause a stresssingularity, but are acceptable ifyou ignore stresses in the vicinity.Remember, you can use selectlogic to ignore the elements inthe vicinity of the point load.
INTROD
INTROD
INTROD
INTROD
Training Manual
Loading & Solution
...Concentrated Forces
In the 2-D quarter symmetry solid model shown at bottom left, notice that
maximum stress SMAX (23,590) is reported at the location of the force.
When the nodes and elements in the vicinity of the force are unselected,
SMAX ( 2 28 ) h b l f hi h i h
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SMAX (12,281) moves to the bottom left corner, which is anothersingularity due to the reentry corner. Reflected about x-z plane
half symmetry model
reentry corner
INTROD
INTROD
INTROD
INTROD
Training Manual
Loading & Solution
Concentrated Forces
By unselecting nodes and elements near the bottom left corner,you get the expected stress distribution with SMAX (7,945) nearthe top hole.
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INTRODC
INTROD
INTRODC
INTROD
Training Manual
Loading & Solution
Concentrated Forces
Note that for axisymmetric models:
Input values of forces are based on the full 360.
O t t l ( ti f ) l b d th f ll 360
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Output values (reaction forces) are also based on the full 360.
For example, suppose a cylindrical shell of radius r has an edge load of Plb/in. To apply this load on a 2-D axisymmetric shell model (SHELL51
elements, for example), you would specify a force of 2rP.
P lb/in
r
2rP lb
INTRODC
INTROD
INTRODC
INTRODC
Training Manual
Loading & Solution
Verifying Loads
Verifying applied loads
Plot them by activating load symbols:
Utility Menu > PlotCtrls > Symbols
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Utility Menu > PlotCtrls > Symbols
Commands --/PBC, /PSF, /PBF
Or list them:
Utility Menu > List > Loads >
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Chapter 10
Structural Analysis
INTRODC
INTRODC
INTRODC
INTRODC
Training Manual
Chapter 10 A. Preprocessing
Geometry
Geometry
Can either be createdwithin ANSYS or imported.
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Include details to improve results:
Goal is to sufficiently model the stiffness of the structure
Add details to avoid stress singularities (e.g. fillets)
Exclude details not in region of interest (e.g. exclude small holes)
Add details to improve boundary conditions (e.g. apply pressure to an
area rather than using concentrated load)
INTRODC
INTRODC
INTRODC
INTRODC
Training Manual
Chapter 10 A. Preprocessing
Meshing
Element type The table below shows commonly used structural element types.
The nodal DOFs may include: UX, UY, UZ, ROTX, ROTY, and ROTZ.
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2-D Solid 3-D Solid 3-D Shell Line Elements
Linear PLANE42SOLID45SOLID185
SHELL63SHELL181
BEAM3
BEAM4
BEAM188
Quadratic PLANE82PLANE2
SOLID95
SOLID92SOLID186
SHELL93 BEAM189
Commonly used structural element types
Material properties
Minimum requirement is Youngs Modulus, EX. If Poissons Ratio is
not entered a default of 0.3 will be assumed. Setting preferences to Structural limits the Material Model GUI to
display only structural properties.
Real constants and Section properties
Primarily needed for shell and line elements.
INTRODC
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INTRODC
Training Manual
Chapter 10 B. Solution
Define Loads
Structural loading conditions can be:
DOF Constraints Regions of the model where displacements are known.
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Concentrated Forces External forces that can be simplified as a point load.
Pressures Surfaces where forces on an area are known.
Uniform Temperature Temperatures applied as a body force used with a reference
temperature to predict thermal strains.
Gravity Accelerations applied as inertia boundary conditions
INTRODC
INTRODC
INTRODC
INTRODC
Training Manual
Chapter 10 B. Solution
Displacement Constraints
Displacement Constraints
Used to specify where the model is fixed (zero displacement locations).
Can also be non-zero to simulate a known deflection
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ONTOANS71
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ONTOANS71---P1
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Can also be non zero, to simulate a known deflection.
To apply displacement constraints : Main Menu > Solution > Define Loads > Apply
> Structural > Displacement
Choose where you want to apply theconstraint.
Pick the desired entities in thegraphics window.
Then choose the constraint direction.Value defaults to zero.
Or use the D family of commands: DK, DL,
DA, D.
Question: In which coordinate systemare UX, UY, and UZ interpreted?
INTRODC
INTRODC
INTRODC
INTRODC
Training Manual
Chapter 10 B. Solution
Concentrated Forces
To apply a force, the following information is needed:
node or keypoint number (which you can identify by picking)
force magnitude (which should be consistent with the system of unitsyou are using)
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8/2/2019 krb ppt
145/183
May 30, 2003
Inventory #0018702-145