COMPUTER AIDED DESIGN
COMPUTER AIDED DESIGN MECH 403
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Date Created: 10/19/15
CosmosWorks Three Material Thermal Study draft22l20l06 Introduction When you are learning a powerful system like SolidWorks and CosmosWorks it is wise to reproduce problems with known solutions to verify that you have properly mastered the interface The purpose ofthis study is to demonstrate how to combine parts with different material properties in a thermal analysis The basic outline is that you must create a SolidWorks part file for each single material part combine them into a SolidWorks assembly and mate the touching surfaces Then you can open the assembly in CosmosWorks specify the material properties of each part bond surfaces where needed apply loads and restraints and solve the equations Usually you will also need to postprocess the results for items of interest Here you will utilize a known 1D solution to verify your use of a 3D code Then you should have no trouble mastering parts of arbitrary 3D geometry The popular heat transfer text by Chapman 1 provides several analytic and numerical studies that can be used a validation exercises One such application Example 22 1 gives the analytic solution for steady temperature and heat ow through a at wall made of three layers of bonded materials The outside of the wall has natural convection to air at 35 C with a convection coef cient of h1 300 Wmquot2 C The outer facing brick has a thermal conductivity of k1 132 Wm C and a thickness of10 cm It bonds to a 15 cm layer of common brick with k2 069 Wm C It in turn is covered with plaster that is 125 cm thick having k3 048 Wm C Finally the plaster convects to inside air at 22 C and has a convection coefficient of h2 8 Wmquot2 C You want to know the inner and outer surface temperatures and the heat flux per unit area through the wall In a 1D solution the temperature through a at wall without internal heat generation will wary linearly with position in each region of constant conductivity k It will be continuous at the bonded material interface but the slope is discontinuous where k changes Likewise the heat ux should be constant and the same in each material You need to determine the two wall surface temperatures at the air and the heat ow through the wall At the end ofthis study the analytic 1D temperatures and head ux will be compared to the computed results The three material part geometries Face brick part Since CosmosWorks defaults to 3D solids you will need to build three different solid parts one for each segment of the wall The respective lengths are specified above The thickness and width of each brick shape to define the wall area needs to be the same Their values can be arbitrary and are usually picked to give good aspect ratios for the elements Here the vertical height is assumed to be 2 cm and the horizontal width is 1 cm Start SolidWorks and begin by specifying the units to be utilized in building the first part Page 1 OH Copyright JE Akin All rights reserved Use Toolsoptionsanocument PropertiesUnits in tne Units panei check ces cm gram sec as yourUnit system it you WWSH seieot feet as tne optionai Duai units for dimensions Tnese units onoioes are seen in Figure 1 wrx System upiianS Daeuneni Pi vemes r Deemei r Fiaciinns Rmin in quot951 Nadiaquot Figure1 selecting the units fortheflrst part We irst part facing bnckWiH Simpiy be an extruded reotangie Buiio it Witn i i dick on Frontinsert SketchRectangie 5 art one corner at tne Origw i drag out tne reotangie Smart dimension tne iengtn to m Pick Eatrude ass oss icon to get tne Extnide pa i oiino extmaion in Direction 1 of arbitrarywid 0M cm OK ne tn FileSaiie as riiename FaceiBnck sioort see Figure 2 new C I m V I 0 His name Fan MKSLDF RI m Figure 2 sketch extruae and save the me brick Page 2 of 17 Copyright JE Akin AH ngnts reserved Common brick and plaster parts Follow a similar process to create the Co mmon Brick part and the Plaster part as summarized in Figure 3 Remember to start with Tools0ptionsDocument Properties Units Fllename Duecllnnl A E W v I39 a lEIEIm 1 Fllename PlasterSLDPRl Figure 3 Forming the nexttwo wall layers Building and mating the assembly needed 2 0 EDS P ewAssembly0K Right click on quotim an assembly insertion progress see Figure 4 In the Insert Component panel highlight the FaceBrick part to start the assembly and to locate all other parts relative to it Click on the CommonBrick art and drag it into the assembly Finally click on the Plaster part and drag it into the assembly L CII parts as in Figure 5 n 1 r surfaces intended for mating are close to each other 0K Page 3 of 17 Copyright JE Akin All rights reserved Wmdaw He D N ma 3 a bnmtatmns Matzvu mt weaned guzer 3 Saw Eldesil nant Emv re mger gamma Anmtztmn neenar nut Evenweb r aNm m 5 an Email Figure 5 Starling the assemth prncvss a w 5 sum Men Mate the touching surfaces perpendwcu ar edges be corncrdent 1 Se ectme pa er chp Mate rcon ust above tne Move Component con 2 Prcktne node 1 crn too homzoma edge or tne race onck and tne correspondmg too outer edge or tne common onck 3 n tne Coincident panel 5e ect corncrdent as tne standard Mater 0K wntersecung tn panel 5e ect corncrdent as tne standard Mater 0K see Frgure 6 Page 4 or 17 Copyngm J E Akm AH ngnts reserved 5 Use the same patrotcothetdeht rhates at the common bhehptaster htertaee 6 Vertfy the rhated asserhbty of the three dtrtereht rhatehats as h thure 7 Use FileSave as to create the Assembly name of HouseiwaH DK thure 7 Figures check and rearrange the assembly orthree pans Figures Mahethefaclng and common buck tmemce N w you have bth a sohd asserhbtywhteh ts eduwateht to the 1D vertftcatton probterh Thts was cteahy a tot more work just to get started than the Mt 1D ahatyttc sotutton But after become t WhHe the very dtmeutt ahd trhpraetteat Page 5 of 17 Copyrtght J E Akm AH hghts reserved Male Selections A Slandaid Males m Emncidenl Slandaid Male E Emnciderl File name Huus wall SLDA Figure 7 Beginning the CosmosWorks Model Pick the CosmosWorks icon fourth from the left ameStudyto get the Study anel thermal as the Analysis type and select a shell as the Mesh type try repeating this laterwith a solid mesh 0K see Figure B an 3quot m E 2 a 7quot 0 mi 93 gt m m 0 a E lt Mesh we siieiim lzlriaJllISLE Figure 3 Eeginng a thermal study of an assembly Select the shells and assign materials Had you picked a solid mesh type you could next directly de ne the three sets ofma 39al properties F the chosen shell type ofmesh using su aces you must rst select the three connected surfaces to be meshed wi h shells ince the problem is really 1D you cou select a y n ofthe four sets ofthree connected faces runningt the front face of the assembly will be employed Now you are using a 2D model to solve the 1D problem Start with the face brick 1 Right clic u panel I get Page 6 of 17 Copyright JE Akin All rights reserved 2 n e Shell Definition paneli set tne Type to him plckthe model from surrace of tne facing brick as tne Selec ed entity as illustrated in Figure Set tneTnickness to 1 an OK Especially note tnis step since tne extrusion tnat option here but 3 u assigned in r is not mailaole nere Whatwould nappen lfyou lnconslstentlytype in 2 cm use i cm tortne nexttwo s s of shells lntneiiiaiiag ipaii i nen 39 39 39 5 Check Custom definedi enter FaceiBrlck as tne Material name type tne tnermal Conductivity value KX as i 32 WmAZ 0 0K see Figure l 6 Repeatmls process forme nexttwo materials as in Figure ii and Figure 12 O Q was a iiin r hch seieieu eniiies mama Figures De netnelaeing hriek shell surlaee area we LlnialElasllcsa DDc v Urlls si r UsiSleaKsmalella i snaanaenaa r L2H ueiniei name Figure in Inpullhe cuslnm material pmpenylnrlhelzce brick Page 7 of 17 Copyright u E Akin All rignts reserved Malanalneme Ca onEvick Selecled enlilies g snaxr Tensile slienglh Nm 2 slaxc Compressive shength Nmquot2 Thickness EIEVLD Yield st m Nm Z ALPx Theimal expansion cuelllcie New m l39 vx Thelma nonducllvily n 59 Wm K Figure 11 thirknp u Salaried eMilEr dens ly Tenxile sirenglh wwz susxc Compresswe slienglh NMAZ mm SlGYLD Yield suen in mm Theimal BXDansIon coelllcia Melvin Wquot 39 Kgtlt Thermal conducle u 48 Wm Kl Figure 12 Setthe shell surface thickness and property forthe plaster Control and create the mesh Knowing the analytic result each layer ofthe wall could be solved exactly with one rectangular element or two triangular elements forming the rectangle However you will generate a general 2D or 3D mesh with a few coarse elements to avoid long skinny high w u an nu y 1 In the manager panel right click on MeshApply Control 2 In the Mesh Control panel select the three faces orthree bodies if3D as the Selected Entities and set Control Parameter element size to a relatively large number li e cm see Figure 13 for example 3 MeshCreateMesh panel enter similar coarse element sizes 0K Page 8 of 17 Copyright JE Akin All rights reserved Mesh Cunlml Selected Enlllles A Eanllal Palamelels l7 Use same elemenl Size Eamvanenl elgmrleenee Low High a l l em v Figure 13 Select the shell regions and force a crude mesh Mequot 39 39 r 39 r 39 r MeshShow mesh Mainly you need to look for bad aspect ratios For shell element assure that the color coded top or bottom sides of all e ements Ge their normal vecto aret e same That is very important 39n shell bending structural models Here the e all gray or orange bottom side color coded Note that he common brick region of elements needs to be Tlippedquot To x that new e w u 39 lg 39 2 MeshFlip shell elements 0K Double check the mesh Muuelneme Housewell sluuy name Summ Meshlype snellmesh Wall using sunam En Hide Mesh Modean Ho s in well Study name Swims Wall Meshtype mums using Figure 14 Assure that all 2D elements have the same top orientation Page 9 of 17 Copyright JE Akin All rights reserved Impose convection loadings panel Loaleestraintsionvection to open tne Convection anel At tne inside Wall picktne edge or race in 3D as tne Selected Entity Set Convection Parameters to n 8 WmAZ c and 295 k as tne air temperature OK Note tne inconsistent need to convert tne airto degrees kelvin Flgure15 or a user 1 wmg1 error garbage in garbage out 4 Repeat step 3rortne outside convection edge race in 3D Cumemuquot onve on gteleclej tnll le anedlan reieneei A unit 5 Czleclzd mils Binecllm Falamelas A i kill 5 39 X wrKZKI l39 295 krivm Figure 15 Seline inside and nutside convection lands 5 3U wwz K I zoo keivn lnsulated segments ThuSi any user action no otner boundary condition is applied to a surrace Essential boundary condition o least one known temperature point via LoaleestraintsTemperature Here you nave done tnat indirectly because or tne nature or any convection boundary condition Thug no be solved ror tne urikriowri temperatures Page 0 or 7 Copyrignt J E Akin All rignts reserved Solve for the temperatures nvoke the equatroh soher h the manager rrght chck Assembly nameRurr fyou Wrsh You to you rtyou have to come backto rtrh a few Weeks or years The resurts of such reharhrhg can be seen rh Frgure16 Summerwur 3 She W g SheHrlGFatejnck39 SheHr ammuni nck39 htanvettmn eutsrue Figure 16 Renamethe material reginns ahu cnhvec Inn lnzds Postprocessing After u uah m ahar r mu r u H You Remember rh ouahtrtres The temperature graorehts and heat tqu are the east accurate You shouro w w w WhHe the other arso rhvohes the rhaterrar propemes Temperature results AS n Vd or rrrrgur 17 Mauerhehe houseweu stuuY heme summeryveu 239 5 PMwa rherheww w 1 rrrestep 1 azsemm memm auremm zssemm zasemm wemm zsaemm zsaemm Figure 17 Linearterrrrrerature drnps Ihrnugh each material Page 11 of 17 Copyngm u E Akm AH Hgms reserved shgh y rhore mermaIWe set ofmformauon rs to probe tor the convecuon surtace aho oossroty the rhte ace temperatures t to tchckm the graohrcs area and setect Probe 2 Ptck oorhts atthe outsroe arr they are about 33 9 C Ptck oorhts atthe rhsroe arr they are about 25 3 C as m thure 18 and the part name Where the probe occurred 313 32 Qi i u rehp cereue 1vp 1twematewm1 mm Beam 3 out ameoum R 2 seem eueum meum zsaeoum Stueyhehe Suhhewteu Ptutupe therhetpun TWE SAED t 22o mat zattzpteetert Figure 13 Prnhing the temperature extremes Graphing Temperatures hsts of therr vatues oh setecteo hhes or surtaces wrth t Rrg tchckm graohrcs area List Selected 2 Setect a the of mterest say the tacrhg b ck oase 3 thth Summary tor the the see Frgure 19 Each hooat vatue rs hsteo h the oahet 4 mm 39 terhperatur retattve postuon on the We thure 20 top Page 12 of 17 Copyngm u E Akm AH hghts reserved Edrt De mtmn Ammate Chvwnq pm 0mmer av Vaclav Mm M Axes Mm me Lumber Figure 19 Selecting lacing hrickln Iisuempemunzs n a swm arfasmon you can prcmne pase ofme common rntenor pncmo hat and grapn Frgure 20 r Tne pra r r grapn a s Frgure 2o ower ngnt Heat flux results erer nonce that the numbers are the sarne except ror sorne roundroff errors Check the p ot an es 1 Rrgnr chckm the grapnrcs area Edit De nitionSettings F zmm NW 39 contour range revers Smce they are both the sarne 27 2 WrnA2 needed a contour p ot rs not Page 13 or 17 Copyngm J E Akm AH ngnrs reserved Aglzl PH 0mm HnlD Study name ChapmnvLZZ Plnl ype ThermaH lutl 35 34 Lin E u 29232nm mmnznaav SUSUSEW 32 N 285 um i an 4 3 4 H H t an m 2 n3 n4 us us 7 an as m Save Hum mm Elase Halv J J A 1 pmmpm Smdy nnme chnpmnngz Slullynume channmuz Pluttyne nemuwma Pinuype Thermaerlml an m z n 4 35 a n7 n as w 2m m Wm Figure 20 Graphing the listed line temperatures 3 To double check this click in the graphics area and select Probe Figure 21 4 Picking nodes on the plaster and facing brick veri es the heat ux result Study name SummelWall Plul lype39 ThermalPlun Time stem 5W ammm 7 quot 39 M Nude lHFquN Mnrz x mm Y mm 2 mm Campunents 7 Dismaylegend r Aulumalic 253 2 7224301 224 21 334 23 412 Plastavr l 2722 257 2 722UUl 224 1 3343 23 412 Plasle 155 2 7234301 738 504 21 334 23412 FaceAEnckrl Max 27 224 175 2 7ZeUUl 8504 1 3343 23 412 FeceEnck1 Figure 21 Probing the constant heat flux Page 14 of 17 Copyright JE Akin All rights reserved You Tne llst can be saved to place ln vour analvsls report Use 1 Under tne studv name ThermalListList Thermal panel 2 t it t tn 7 39 UXN as tne Component 0K 3 Tne List Results panel WlH appear as seen ln Flgure 22 mutant mam omewn mth l l jun same lelaenee gennelly WA Llslavllnn r game Erlelm rbedutsMEx v F Sorlbttalle Waldo s j E Wk Deflne ContactG Eammrem HFLUXN Remlbrlnealnux sepvnta r Figure 22 List the maximum heal ux lnund in the mesh Validation 1 plaster surtace temperature to be 25 4 c 77 7 F and tne constant neat ux per unlt area to be 27 2 WmA2 8 63 Btun m2 Tnls problem was also solved Wltn a 17D nnlte element elements uslng Matlao o o respectlvelv Refere 1 Alan J Chapman Fundamentals of Heat Transfer MacmlHan New York 1987 2 J Ed Akln Flnlte Element Analyslsvvltn EnorEStlmatorS Elsevler 2005 Page ls or 17 Copvngnt u E Akln All ngnts reserved Temperature Through a Three Material Wall 0 Nodalvalues lt1 Airsurface 015 Position m Figure 23 Onedimensional validation plot Page 16 of 17 Copyright JE Akin All rights reserved Conduction through three layered planar wall with convection Ref AJ Chapman quotFundamentals of Heat Transferquot Macmillan 1987 Example 22 pages 46 47 Outside o convection at 35C to facing brick f to brick b to wall plaster 4p to inside 7i convection at 22C Note the essential BC are hidden in the convection air temperatures convection x71 x72 x73 x74 convection air hio T70 1 2 3 air hii T71 T71 T72 T 3 T 4 Pl L2 L2 L2 Pl Connectivity list e i j l l 2 L2 2 2 3 L2 3 3 4 L2 4 l 0 Pl 5 4 0 Pl Set given constants L f 0l L b 015 L p 00125 conduction lengths Kf l 32 Kb 069 Kp 048 thermal conductivities T o 35 T i 22 air temperatures out in ho 30 hi 8 convection coefficients Manually assemble 4 by 4 square matrix terms DOF l 2 3 4 SK7fL7fhio K7fL7f 0 0 K fL f K fL f K bL b K bL b 0 of 7 KbLb 7 7 KbLbK7pL7pl KipLip O 0 dipLip KipLipmii l C hioT4o 0 0 h7iT7i Assemble 4 by 1 source terms T S C Solve for four temperatures C q f K7f T2 Tl Lif heat flux through wall WmA2 Figure 24 Script for 1D FEA model Page 17 of 17 Copyright JE Akin All rights reserved