mech-intro 13.0 l08 results

Customer Training Material

L t 8Lecture 8

Results and Postprocessing

Introduction to ANSYSIntroduction to ANSYSMechanical

L8-1ANSYS, Inc. Proprietary© 2010 ANSYS, Inc. All rights reserved.

Release 13.0November 2010

Introduction to ANSYS Mechanical

Customer Training MaterialChapter Overview• In this chapter, aspects of reviewing results will be covered:

A. Viewing ResultsB. Scoping ResultsC. Exporting ResultsD. Coordinate Systems & Directional ResultsE. Solution CombinationsF. Stress SingularitiesG. Error EstimationH. Convergence

• The capabilities described in this section are applicable to all ANSYSThe capabilities described in this section are applicable to all ANSYS licenses, except when noted otherwise




Customer Training MaterialA. Viewing Results

• When selecting a results branch, the Context toolbar displays ways of viewing results:

Min/Max Probe

Displacement Scaling Display Method Contour Settings Outline Display

Vector Display Controls

• In addition, the “Timeline” also has an animation toolbar which lets the user set animation controls

DistributeDistribute Export



Play Pause Markers Frame Rate Control


Customer Training Material… Displacement Scaling• For structural analyses (static, modal, buckling),

the deformed shape can be changed:– By default, a scale factor “multiplies” actual displacements. – The user can change to true scale or undeformed displays.

True ScaleAutomatic Displacement Scaling




Customer Training MaterialLegend Controls• Right Clicking on the legend in the graphics area allows the user to

modify the legend controls.

Edit Value

Export/Import/Switch to a saved legend setting

Horizontal/Vertical legend

Display Date/Time

Display Max/Min label on the legendSwitch to Logarithmic Scale

Increase/Decrease Contour Bands

g

Switch to Scientific NotationNumber of Significant Digits

• Continued



Continued . . .


Customer Training Material… Legend ControlsThe legend bounds can be manipulated to show result distributions more clearly for contour plots.

Max/Min values are unchanged

Click and drag contour dividers (or type in) to specify contour ranges.

A non-uniform distribution of



contours can be used as well.


Customer Training Material… Manipulating the Legend

• Independent Bands allow neutral colors to represent regions of the model above or below the specified legend limits.

Legend Contour Range




Customer Training Material… Display Method• The “Geometry” button controls the contour display

method. Four choices are available:IsoSurfacesExterior

“Exterior” is the default display option and is most commonly used.

“IsoSurfaces” is useful to display regions with p y gthe same contour value.

“Capped IsoSurfaces” will remove regions of the model where the contour values are above (or below) a

Slice PlanesCapped IsoSurfaces

( )specified value.

“Slice Planes” allow a user to ‘cut’ through the model visually. A capped slice plane is also available, as shown



also available, as shown on the left.


Customer Training Material… Display Method• Capped IsoSurfaces are manipulated by an independent controller:– Icons allow isosurface cap to be top or bottom.– The striped areas of the legend show what values will not be displayed.p g p y– The cap threshold can be controlled via the slider or by typing the value

directly



Top Capped Isosurface Bottom Capped Isosurface


Customer Training Material… Contour Settings• The “Contours” button controls the way in which

contours are shown on the model

Contour BandsSmooth Contours

Solid FillIsolines




Customer Training Material… Outline Display• The “Edges” button allows the user show the

undeformed geometry or mesh

No Wireframe Show Undeformed Wireframe

Show Undeformed Model Show Elements




Customer Training MaterialSection Planes

• Section Planes can be added and edited in both the preprocessor as well as the post processor.– To add a section plane select the “Draw Section Plane”

icon, then click-drag with the left mouse.Selection planes can be turned on/off using the check– Selection planes can be turned on/off using the check box in the details view.

– Delete section planes using the delete icon.– Edit section planes by highlighting desired plane name

and using the ‘handle’ in the Graphics window.g p

Move a slice plane by dragging handle Sliced view of geometry in Preprocessor

Sliced view of model in Post Processor with results

Click on one side of bar to cap view




Customer Training MaterialProbe Tool• The Probe Tool allows you to scope a result object

to a location and make that result parametric.• The Probe Tool can be scoped to geometry, a local

coordinate system or using a remote point.• The orientation of the result item can be with respect

to global or local coordinate systems.




Customer Training Material. . . Probe Tool• Probe Tool example:– Local coordinate system defined as shown– Probe located at local CS– Stress results (all) requested

Local CS

Probe Location




Customer Training MaterialCharts and Tables• Combine results data from multiple steps (static or transient) into

charts and/or tables:– Select “New Chart and Table” icon.– From the details “Apply” the desired result(s).

• Use the CTRL key to select multiple results.– Select desired display items in details.




Customer Training MaterialAnimation Controls

• The animation toolbar allows user to play, pause, and stop animations• Note: animations are accessed via the “Timeline” at the bottom of the

graphics screen

Start/Stop/PauseControl resolution and speed

Distributed animation interpolates results while results sets animates only solution points.

Export video (avi) file



Note: pause feature available during playback


Customer Training Material… Alerts• Alerts are simple ways of check to see if a scalar result quantity

satisfies a criterion:– Highlight the particular result branch, RMB and insert an Alert.– In the Details view, specify the criterion.

– In the Outline tree, a green checkmark indicates that the criterion is satisfied. A red exclamation mark indicates that the criterion was not satisfied.




Customer Training Material… Vector Plots• Vector plots involve any result quantity with direction, such as

deformation, principal stresses/strains, and heat flux– Activate vectors for appropriate quantities using the vector graphics icon

– Once the vectors are visible their appearance can be modified using the vector display controls (see next slide for examples)

Vector Length Control Vector Density Control

Proportional Vectors Equal Length Vectors Grid AlignedElement Aligned Line Form Solid Form




Customer Training Material… Vector Plots• Examples

Proportional LengthSolid Form, Grid Aligned p g



Solid Form, Equal LengthEqual Length


Customer Training Material… Multiple Viewports• Multiple viewports can be used to display various images at the same

time (model or postprocessing data).– Useful to compare multiple results, such as results from different

environments or multiple mode shapes




Customer Training MaterialB. Scoping Results• Limiting results displays can be useful when postprocessing:– Scoping automatically scales the legend to results for selected regions.

• To scope contour results:p– Pre-select geometry then request the result of interest.– The non-selected geometry will be displayed as translucent.




Customer Training Material… Scoping Surface/Part Results• Some examples of scoping results on surfaces/parts:

Scoping results on a single part

Stress results on selected surfaces



Vector Principal Stresses on single part


Customer Training Material… Scoping Edge & Vertex Results• Results can be scoped to a single edge (or vertex):– Select edge(s) for results scoping.




Customer Training Material. . . Construction Geometry• Construction geometry consists of either a

path or surface.• Paths are defined using coordinate systems,

model edges or existing points.• Surfaces are located and oriented using

coordinate systems.




Customer Training Material. . . Scoping to a Path or Surface• Results may be mapped onto construction geometry in the details:

Path Plot Example

Surface Plot Example




Customer Training Material. . . Scoping to a Path• Path results may also be displayed in graphical form.• The X axis may be displayed as path location (S) or time (transient

analyses).




Customer Training Material. . . Linearized Stress• Using the path plot feature a linearized stress calculation can be

plotted (commonly used various structural codes such as ASME).




Customer Training MaterialC. Exporting Results

• To export Worksheet tab information:– Select the branch and click on the Worksheet tab.– Right-click the same branch and select “Export”.g p

• To export Contour Results:– Right-click on the result branch of interest and select “Export”.

• Tabular data from Mechanical can be exported to Excel:p– Select the cells to be exported.– Right click > Copy cell to copy all the data from the cells.– Paste into Excel.

Export Worksheet Export Results



pExport Tables


Customer Training Material… Exporting Results• To include node locations and vector directions in results exports,

change the “Include Node Location” option to “Yes” under “Tools menu > Options… > Mechanical: Export”




Customer Training MaterialD. Coordinate Systems

• Results containing directional components can be mapped to a local coordinate system:– Select from defined coordinate systems in the drop down list shown in y p

the detail window.– Direction Deformation, Normal/Shear Stress/Strain, and Directional Heat

Flux can use coordinate systems.




Customer Training Material… Coordinate Systems• For the model shown below, displaying results in the local cylindrical

system transforms stresses into that system.

Stresses in Global Y-Direction Stresses in Local Cylindrical Y-Direction




Customer Training MaterialE. Solution Combinations

• In the project schematic, duplicating an analysis cell below the Model branch (Setup, Solution or Result), allows the creation of Solution Combinations to quickly evaluate results combinations.

• Solution combinations are only valid for linear static structural analyses.• The supports must be the same between Environments (only the loading can

change).• ANSYS Professional license and above.




Customer Training Material. . . Solution Combinations

With the Model branch highlighted a “Solution C bi ti b h f th t tCombination can be chosen from the context menu.

A new branch is inserted where combined results b t d d t i dcan be requested and retrieved.

With the Solution Combination branch highlighted, the worksheet view allows multiple environments to be combined Note: a multiplication factor mayto be combined. Note: a multiplication factor may be included in combinations (see below).



Solution Combination = Coef 1 * Environment 1 + Coef 2 * Environment 2 + . . .


Customer Training Material… Solution CombinationsExample: a brake caliper is simulated in both standing and rolling configurations. After the 2 environments have solved a2 environments have solved a resulting combination shows the effect of both.



Solution Combination


Customer Training MaterialF. Stress Singularities• In most finite-element analyses as the mesh is refined one expects to

get mathematically more precise results.– Quantities directly solved for (degrees of freedom) such as

displacements and temperatures typically converge with little difficulty.– Derived quantities, such as stresses, strains, and heat flux, should also

converge as the mesh is refined but typically not as smoothly as DOF.I th d i d titi ill t th h i– In some cases these derived quantities will not converge as the mesh is refined and may even diverge.

– These cases are sometimes the result of some form of stress singularity.

ForceAreao ce

=σ As Area Zero ∞⇒σ




Customer Training Material… Stress Singularities• In a linear static structural analysis there are several situations which

may cause artificially high stresses:

Idealized Geometry Point Constraints Point Loads

• In the above situations, refining the mesh at the artificially high stress area will keep increasing the stresses.

⇒L8-36

ANSYS, Inc. Proprietary© 2010 ANSYS, Inc. All rights reserved.


∞⇒σ


Customer Training Material… Stress Singularities• The Remedy:– If the singularity is not in an area of interest one can usually scope

results to regions of interest.– If the singularity is in the area of interest there are several ways to obtain

more accurate stress results:• Model geometry with fillets or other details which do not cause geometric

discontinuitiesdiscontinuities.• Apply loads and/or constraints spread over areas rather than point locations

(see below).

Example



Point Loading Distributed Loading


Customer Training MaterialG. Error Estimation• You can insert an Error result based on stresses (structural), or heat

flux (thermal) to help identify regions of high error (see example next page).

• These regions show where the model could benefit from a more refined mesh in order to get a more accurate answer.

• Regions of high error also indicate where refinement will take place if convergence is used.




Customer Training Material. . . Error Estimation

• Error plot shows region of high element energy where mesh refinement may improve the quality of the result.improve the quality of the result.

• In the thin plate example the initial solution shows higher energy levels between the 2 holes.between the 2 holes.

• The refined mesh (bottom plot) shows a reduction in local error.

• Please note, error is a relative measurecomparing individual elements to one another The actual value of the energy isanother. The actual value of the energy is generally not significant.




Customer Training MaterialH. Convergence

• As the mesh is refined, typically the mathematical model becomes more accurate. However, there is computational cost associated with a finer mesha finer mesh.

• Obtaining an optimal mesh requires the following:– Having criteria to determine if a mesh is adequate.

I ti l t l h d d– Investing more elements only where needed.• Performing these tasks manually is cumbersome and inexact:– The user would have to manually refine the mesh, resolve, and compare

lt ith i l tiresults with previous solutions.• Mechanical has convergence controls to automate adaptive mesh

refinement to a user-specified level of accuracy.• Convergence controls cannot be used on all result items.




Customer Training Material… Convergence

• To use this feature select a result item RMB and insert “Convergence”:– Select max/min value for convergence and allowable change.– In the Solution branch details input the max number of refinement loops.




Customer Training Material… Convergence• After the solution is complete one can view the

results and the last mesh (symbols in the tree indicate success or failure to converge):

The mesh is refined only where needed (see below)– The mesh is refined only where needed (see below).– The Convergence branch shows the trend for each

refinement loop.



Convergence Divergence


Customer Training Material… Convergence & Scoping • A useful technique to avoid stress singularities when using

convergence is to scope results away from them.• If the singularity region is not of interest, one can scope results on

selected part(s) or surface(s) and add convergence controls to those results only:– Provides control on where to perform mesh refinement.– Ignores areas of artificially high stresses which are not of interest.

– Example:

Possible stress singularity



Region of interest


Customer Training Material… Convergence & Scoping Example

Convergence controls added to the entire model.

Geometric discontinuity causes a stress singularity causing divergence.

Solution becomes verySolution becomes very costly by including the stress singularity.

Convergence controls on scoped results allows adaptive refinement only in user-specified locations.

Provides more control over the mesh and the adaptive solution.



Accurate stresses realized in the region of interest.


Customer Training MaterialI. Workshop 8.1 – Advanced Results Processing

• Workshop 8.1 – Results Processing• Goal:

A l th h i l h b l d th f– Analyze the mechanical arm shown below and then use some of the advanced postprocessing features to review the stress and estimate the error associated with a default mesh.



mech-intro 13.0 l08 results

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