sindag_femap

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Building Your First

Models in FEMAP

Network Analysis, Inc.4151 W. Lindbergh Way, Chandler, Arizona 85226

Phone 480-756-0512 Fax 480-820-1991 [email protected] www.sinda.com


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Building first models in SINDA/G for FEMAP

Third Edition January 2004

Copyright 2001 by Network Analysis Inc. All rights reserved. No part of this publication may be reproduced, storedin a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, orotherwise, without the prior written permission of the author and publisher.


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PROBLEM #1

HEATING AND CONVECTION ON A RECTANGULAR SURFACE

Outline

This problem will introduce you to basic FEMAP commands by building a simplerectangular surface. (It is assumed that you have basic knowledge of the SINDA/G input filestructure, if not, do the Introduction to the SINDA/G Thermal Analyzertutorial first). You will seehow FEMAP assigns geometry and the resulting conductance and heat capacity values to nodes.You will impose a constant heat load to the surface while cooling the surface with uniformconvection. Then you will analyze the model by running FEMAP and view the steady state nodaltemperatures in an output file. Dont worry about units for this problem; we will discuss units inlater problems.

Steps

1) Create a Surface

2) Create a Material3) Create a Property4) Mesh the Surface5) Apply Heat Loads6) Save the Model7) Run FEMAP8) Examine Results

Open FEMAP

Click the following buttons:Start, Programs, SINDAG Demo, SINDA ATM, SINDA ATM (FEMAP)

Step (1) Create a 1x2 Rectangular Surface

Convection to 25 deg

H=2.2

Total heat load = 40

Plate size 2 long 1 wide

K = 320, Density = 1, Cp = 240

A) Geometry

B) Surface

C) Corners


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Ctrl A will auto-size the geometry in the window.

Step (2) Create a Material

Click the following buttons:

The Define Material box appears

Enter (0,0,0) for the 1st

coordinate in the pop-upbox and press OK, thenenter (2,0,0) for the 2

ndpoint

OK, (2,1,0) for the 3rd

, OK,and finally (0,1,0) for the 4

th,

OK. Press ESC or Cancelto terminate this command

A) Model

B) Material

A) Fill in the Title field with Problem 1Material.

B) Fill in Thermal Conductivity box with320.

C) Fill in the Density box with 1.

D) Fill in the Specific Heat box with 240.

Note the material record is assigned an IDnumber.

Click OK. A box to define a second materialpops up which we dont need, so click Cancel.


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SINDA/G Advanced Modeler 5

Step (3) Create a Property


The Define Property box appears

A) Model

B) Property

A) Fill the Title field with Prop1.

B) Select the material recordyou just created by clicking

the arrow in the Materialbox. The property recordhas ID = 1.

C) Enter 1 in the

Thicknessesbox located in

the Property Valuessection.

Click OK. Again you areprompted to create anotherproperty. We wont need this,so click Cancel.


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Step (4) Mesh Surface


The Default Mesh Size box appears

A) Mesh

B) Mesh Control

C) Default Size

Note the default size is set at1 length unit. You can set thesize of the mesh in this box.1 is OK for this problem.

Click OK.


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Next, click:

The Entity Selectionbox appears

The Automesh Surfaces box pops up

A) Mesh

B) Geometry

C) Surface

Select the surface withthe cursor or Select All.

Click OK.

Assign your property record by

clicking on the Propertyboxarrow.

Click OK.


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Right click anywhere in the window and choose Workplane.

The Workplane Management box appears.

Ctrl G, will remove the ruler lines by regenerating the drawing. See below.

Step (5) Apply Heat Loads

We will now heat the surface uniformly and apply convective cooling.


Uncheck the Draw Workplane

box.

Click Done.

A) Model

B) Load

C) On Surface

You have now meshed your original

1x2 surface into two elements, each1x1 in size. The elements havenodes at each corner with the centernodes shared by the two elementsfor a total of 6 nodes.


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The Create or Activate Load Set box opens

The Entity Selection box appears

The Create Loads on Surfacesbox appears

The Entity Selection box appears again

Fill in the Title box with Heat Load and Convection.

Click OK.

Click Select All on the pop-up box to select the surface.Click OK.

A) Select Nodal Heat Flux.

B) Enter 40 for the Flux value.

Click OK.

We should note here that FEMAPdoes not use correct thermalterminology. This option will apply40 power units total to the surface.

Click Select All on theSurfaces box.

Click OK.


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The Create Loads on Surfaces box appears again

Lets change the view:

Press F8.

Your window should look similar to the figure below.

Drag the cursor over the figure and note the node numbering. Click on the box again and repeatfor the other options.

A) Select Convection.

B) Fill in 2.2 for the Coefficient.

C) Fill in 25 for the Temperature.

Click OK.

We dont have any more loads to applyso hit Cancel on the pop-up box.

Select Dimetric.

Click OK.

This makes the loading a littleeasier to see.

Click the button in the lower righthand corner that says off.

Select Node. . .in the pop-up box.


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The FEMAP dashboard will appear

Lets examine the input file.

Click SINDA/G Input File (.SIN)

This will bring up the .SIN file.

Hit the Translate and run SINDA/G buttons.

We will run in the default mode, which is thesteady state routine SNSOR.

The SINDA/G

translator converts theFEMAP neutral file

into a SINDA/G input

file (.SIN extension)


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Before we analyze our model, lets note how the FEMAP/SINDA/G translator assignssurface area to the nodes and constructs conductors between the nodes. The elements aredivided in s. Each corner node will be assigned of the element while the center nodes (2and 5) will get two s. This will be reflected in the capacitance values assigned to the nodes andthe conductance values for the conductors between the nodes. The translator constructsconductors between the nodes by placing conductors around the perimeter of the elements andtwo diagonal conductors.

Label the diagram below with the node numbers, nodal capacitance values, conductor values andpowers by examining the data blocks as described below. Node numbers were noted in Step (5).

Consider how the geometry affects these values.

In the NODE DATA block, besides the 6 nodes we had in FEMAP, SINDA/G has created aconvection node, node 7. It is a boundary node (denoted by the minus sign) with a temperature of

25. Note in the capacitance field that the capacitance values are proportional to the areas (reallyvolumes) assigned to the nodes.

Notice in the CONDUCTOR DATA block that conductors have been constructed between thesurface nodes and the convection node with conductance values proportional to areas assignedto the nodes. What is the conductance in the Y direction across an element? Do the conductorson one element add up to the elemental conductance?

In the SOURCE DATA block, the power assigned to each node is proportional to the areas

assigned to the node with the total power equal to 40. This is true with the Nodal Heat Fluxoption we took.


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Step (8) Examine Results

Congratulations! You have finished your first FEMAP model. Please direct all comments andquestions to [email protected].

Close the .SIN file and click (A) SINDA/GOutput (.SOT)

Now we can examine the output file.

Scroll down to the bottom of the file andnotice the surface node temperatures of34.0907 and the node 7 temperature is 25.Also note that SENGIN= 4.00000E+01.SENGIN is the total energy input into thesystem.

Close the .SOT file.

Click (B) Exit to SINDA/ATM, button and

return to FEMAP.


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PROBLEM #2

STEADY STATE AND TRANSIENT ANALYSIS OF A PC BOARD

FEMAP is a model builder and results processor for the SINDA/G Thermal Analyzer. TogetherFEMAP and SINDA/G provide a powerful and flexible thermal design system. In this problem youwill see how to:

Build geometry

Run steady-state and transient analysis

Modify your model, adding heat and cooling

Alter the input file

Create time-dependent heat sources

Post-process your model to create color temperature contours suitable forpresentations and even use animation to create a movie

Quickly view your results in SINDAPLOT, the plotting package that is included

with FEMAP. It is also easy to create output files for importing into Excel or otherspreadsheets.

Outline

In this problem you will create a model of a PC board. We will analyze the board under differenttemperature, heating and cooling conditions. In the first section we will use FEMAP to build amodel that has its ends fixed at T = 25

oC with a uniform heating applied to the board. We will then

analyze the model with SINDA/G, compare the results with the analytical solution, and create acolor contour map. Next we will add, remove and mix different temperature, heating and coolingconditions and then post-process and graph the results.

The basic steps are:

1) Create a Surface2) Select Units3) Create a Material4) Create a Property5) Mesh the Surface6) Create Load Sets7) Save the Model8) Run FEMAP9) Examine the input and output files10) Post-Process11) Create Load Set with Convective Cooling12) Combine Load Sets 1&2

13) Run SINDA/G14) Examine the .SIN and .SOT files15) Post-Process16) Create a Time-Dependant Heat Source17) Combine Load Sets 3&418) Run and Analyze the Model19) Plot Results using SINDAPLOT20) Post-Process with Animation


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Step (1) Create a 8x12 Rectangular Surface

Open FEMAP, if it is not open, (under Programs, SINDA ATM (FEMAP)) click the followingbuttons:

The Locate box appears

Enter (0,0,0) for the 1st

coordinate in the pop-up box and press OK.

Enter (12,0,0) for the 2nd

point and press OK.

Enter (12,8,0) for the 3rd

point and press OK.

Enter (0,8,0) for the 4th

point and press OK.

Press ESC or Cancel to terminate this command.

CtrlA, will automatically size the geometry in the window.

A) Geometry

B) Surface

C) Corners


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Step (3) Create a Material


The Define Materialbox appears

A) Model

B) Material

Click Load.

Select Copper C10200.

Click OK.

The title field is automatically filledin. You can change it if you like.

Click OK.

A box to define a 2nd

material popsup which we dont need so Cancelor Esc.

You can select from large

library of material

properties or create yourown libraries or manually

enter the values in the

property fields.


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Step (4) Create a Property


The Define Property box appears

Again you are prompted to create another property. We wont need this.

Click Cancel.

A) Model

B) Property

A) Fill in theTitlefieldwith Cu Cladding.

B) Select the materialrecord you just createdby clicking the arrow in

the Material box.The property recordhas ID = 1.

C) Enter 0.00615 in the

Thicknesses box.

D) Click OK.


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The Entity Selectionbox appears

The Automesh Surfaces box appears

The Workplane Management box appears

Select the surfacewith the cursor orclick Select All.

Click OK.

Click the Property box andchoose your property.

Click OK.

You have created 24 elementson the surface, the elementshave nodes at each corner,there is a total of 35 nodes.

Your window should looksimilar to this window.

Right click on the window andchoose Workplane

Uncheck the Draw Workplanebox.


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Run the cursor over the left end of the board, notice the left edge becomes highlighted. When theedge is highlighted left click on your mouse this will select the curve.Do the same for the right edge. OK.

The Create Loads on Curves box appears

You are placed back in the Entity Selectionbox to pick another load on another curve; wewont need this so click Cancel.


A) Select the Temperature

option.

B) Fill in the Temperature fieldwith 25.

C) Click OK.

A) Model

B) Load

C) On Surface


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The Create Loads on Surfaces box appears

To view the model from a different angle, press F8.

The View Rotate box appears

This will rotate the view, if the previous view is desired, XY Top will restore the view.After rotating, your window should look similar to this:

Select the surface with yourmouse or hit the Select Allbutton.

Click OK.

A) Pick Nodal Heat Fluxoption.

B) Enter 8 into the Fluxfield.

Click OK.

Click Cancel to close the

Entity Selection box thatappeared.

Select Dimetric.

Click OK.


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Step (7) Save the Model


Before we run the analysis, lets see what the analytical result should be. Onecan compute the temperature at the midpoint position by evaluating the following equation:

wdk

QLTmid 8

25+=

Where:

Q= 8 watts, the power inputL = 12 inches, the length of the boardw= 8 inches, the width of the boardd= 0.00615 inchesk= 9.93553 watts/inch-

oC, thermal conductivity of the copper

For these values =Tmid 49.55o.

A) File.

B) Save As.

Enter Problem2 for yourmodel. Dont use spaces inyour name for the time being.

Click Save.


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Step (8) Run SINDA/G


The SINDA/ATM Thermal Solution Managerbox appears

A) Click on SINDA/G.

B) Click Run SINDA/G.

Click Translate and run SINDA/G.

We will run in the default mode, whichis the steady state routine SNSOR.


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The Select Postprocessing Data box appears

Now click the Contour button on the right.This will draw the color contours onto your model drawing.Your drawing should look similar to this one.

Click the button (on the Status Bar, see arrow above) in the lower right hand corner that saysOff and select Node if it is not selected already. Drag the cursor over the figure and note thenode numbering and the temperatures of the nodes. Click on the button again and repeat for theother options if you like.

Select 31..temperature in theContour field.

Click OK.

Contour


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Ctrl G will redraw the picture showing that Load Set 2 is active; this is also shown in the Status

Bar.

Your drawing should be similar to this one.

Select the surface by left clickingon the surface of the drawing.

Click OK.

A) Select Convection.

B) Enter 0.002 in the Coefficientfield.

C) Enter 25 in the Temperaturefield.

Click OK.

Click Cancel on the Create Loads on

Surfaces box.


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Step (13) Run SINDA/G

Prior to running the model, make sure that Load Set 3 is active. Cntrl G will redraw the loads, anduse F8 if you would like to change the view.

Follow the instructions in Step (8). (If an overwrite message pops up, click Yes.)

Step (14) Examine the .SIN and .SOT files.

Follow the instructions in Step (9) in order to examine the.SIN and .SOT files.

You will notice that the .SIN is the same as before exceptthere is now an additional boundary node set at 25

o.

Additional convection conductors connect this node andthe nodes on the surface. The nodal temperatures in the.SOT file are accordingly adjusted.

If you like, manually change some of the conductancevalues in the conductance fields (the 4

thcolumn) and

re-run the model.

Step (15) Post-Process

Examine the results in FEMAP.

You are not limited to FEMAP

when you would like to alter your

models. In your text editor you

can, for example, change the

temperature of the boundary

nodes, alter the conductance

values, add nodes and conductors

etc. It is possible to put in

capacitance field formulas like: =

CP*XMASS or replace the

conductance field with:

= COND*AREA/XLEN. You can

add if then statements and other

logic. SINDA/G is very powerful

and flexible.


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We will now apply this power function to a single node.



Using your cursor to navigate and left clicking, select a node where you want to supply the power.For this example node 34 was chosen (or type in 34 in the ID field).

Create a new Load Set by clicking the Ld:3button.

Change the ID to 4.

Change the Title to Power Function.

Click OK.

A) Model

B) Load

C) Nodal

The x,y data can be exported to and

imported from the Function

Definition box to a spreadsheet

using the Get and Put

commands. Put will put the data

on the clipboard and Get will getit from the cli board.


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The Transient SINDA/G Solution Setup box appears


Click Translate and run SINDA/G. (If you would like to change the TIMEND or OUTPUT fields forsubsequent runs youll need to Click Set Operations Block to incorporate the changes you justmade.)

Examine the .SIN and .SOT files as performed previously. You will notice that the power functioninformation is contained in an array listed in the ARRAY DATA block, you can modify this array ifyou like, the first number is the array name. The power function that uses the array is called inthe SOURCE DATA block with the SIT function. In the .SOT file you can see the temperatureslisted for all the nodes at each output time.

Step (19) Plot the Results Using SINDAPLOT

A) SNDUFR

B) Fill in the TIMEND field with 20.

C) Fill in the OUTPUT field with 0.2.

This will produce a transient run for 20seconds with node temperatures written tothe .SOT file every 0.2 seconds. (SNDUFRis one of many transient routinesavailable.)

OK.

Click SINDAPLOT then SINDA Output File in thepop-up box. Next click Select and then Quick Plot. Atemperature vs. time plot for all the nodes will then bedrawn.


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Your plot should look similar to the diagram above.

You can zoom in on a section of the plot by clicking Plot, Zoom. Left click to draw a box aroundthe desired section and left click again. Repeat this if you like. UnZoom under the Plot button willredraw the plot to the original size.

SindaPlot is a full-featured program. You can select data from different model runs to plottogether and there is even an equation editor. Under the Plot, List commands you can selectdata points to copy into a spreadsheet or text editor.

Close SindaPlot and return to the SINDA/ATM dashboard.

Step (20) Post-Process with Animation

Because FEMAP used bitmap images to construct the temperature contour drawings you will belimited to the number of frames that can be constructed. The number of frames is limited by yourcomputers amount of RAM, virtual memory and video settings etc. So to reduce the amount offrames, increase the Output time to 1 sec.

A) On the SINDA/ATM Dashboard, click TR Setup, change the OUTPUT field to 1.B) Click OK.C) Click Set Operations Blocks.D) Click OK on the Caution box that appears.E) Click Run SINDA/G.F) Return to FEMAP by clicking Exit to SINDA/ATM

Then repeat the steps for importing the data just like you did in Step (10). Then enter31..Temperature in to the Deformation field.


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Now you will need to click the View Select button on the top tool bar as shown in the figure on thefollowing page.

The View Select box appears, click these buttons:

View Select

A) Select Animate-MultiSet.

B) Check Contour.

C) Check Skip Deformation

D) Click Deformed and ConData.


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The Select PostProcessing Data box appears, chose, as shown below, the beginning and endtimes for the animation interval you wish to view. Increase the increment size if you wish. Placingan n in this box will animate every nth output set.

Now click the following buttons:

A) View

B) Advanced Post

C) Animation


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Step (4) Viewing the Post-Processed Model with the Dynamic Viewing

Options

A) Close FEMAP and reopen it. The file is too large to save in the demo mode. OpenCadPart.MOD located in the in the C:\SGDEMO\FEMAP\Examples directory using the File,

Open, commands. You should see a color contour model of the part.

B) Click View, Advanced Post, Dynamic Cutting Plane Grab the control button with yourmouse (see the figure below) and drag it back and forth and watch the cutting planes movethrough the part. The colors dont show in the demo mode. By clicking on Plane you can defineother planes and opening Methods^, will allow you to define planes by clicking on nodes, points,normals, etc.

Dynamic Cutting Plane view of temperature contours

We hope you enjoyed this short tutorial introducing you to some of the power and flexibility of theFEMAP model builder with the SINDA/G analyzer.

Please direct all comments and questions to: [email protected]


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