2008 International ANSYS Conference

Transcription

1 28 International ANSYS Conferene Piezoeletri Fan Moeling FSI Analysis using ANSYS an CFX Courtesy of PIEZO Systems In. Rih Lange, Stephen Sampoli, Naseem Ansari, an Dan Shaw ANSYS In. 28 ANSYS, In. All rights reserve. 1 ANSYS, In. Proprietary

2 Sope of Presentation Outline the workings of the Piezoeletri fan Disuss the proessing of the Piezoeletri ata Show analysis settings Disuss the Coupling with CFX Show results 28 ANSYS, In. All rights reserve. 2 ANSYS, In. Proprietary

3 The Piezoeletri Fan Piezoeletri Fan Spot Cooling for Eletroni Components Low Magneti Permeability Blae riven by Piezoeletri Bimorph Courtesy: PIEZO Systems In Bimorph Blae FR4 Boar 28 ANSYS, In. All rights reserve. 3 ANSYS, In. Proprietary

4 Piezoeletriity Piezoeletriity is a property of some materials (notably rystals an ertain eramis) to generate an eletri potential in response to applie mehanial stress Piezoeletri effet is reversible Materials exhibiting the iret piezoeletri effet (stress eletriity) also exhibit the onverse piezoeletri effet (eletriity stress) For example, lea zironate titanate rystals exhibit a maximum strain rate of ~.1% For stress inue eletriity in piezo-materials, voltage often varies in time 28 ANSYS, In. All rights reserve. 4 ANSYS, In. Proprietary

5 Finite Element Moel with Bounary Conitions Courtesy: PIEZO Systems In Fix Support at holes Bottom piezoeletri Layer: Volt Top Piezoeletri Layer: 115 [V] sin((2π/.4[s])t) The voltage variane proues the fan motion. Two piezoeletri layers 28 ANSYS, In. All rights reserve. 5 ANSYS, In. Proprietary

6 28 ANSYS, In. All rights reserve. 6 ANSYS, In. Proprietary Piezoeletris - Equations L F V u K K K K V u C C V u M V Z Z u v u T Strutural Terms noal fores noal isplaements mass amping stiffness Dieletri Terms amping permittivity eletri potential eletri harge oupling terms

7 Moel Input The equation esribing the voltage variation is reate in ANSYS Classi equation eitor Create the funtion an save it One the onstants in the equation are efine, a table is reate in ANSYS that esribes the speifi equation The log file of the resulting table an easily beome a Comman objet in Simulation The bounary onition then simply gets applie as a tabular loa 28 ANSYS, In. All rights reserve. 7 ANSYS, In. Proprietary

8 Funtion an Table Ansys Utility Menu Parameters> Funtions> Define/Eit Enter the funtion, efining the voltage as a onstant Volume File>Save (give a name) Ansys Utility Menu Parameters>Funtions>Rea From File 28 ANSYS, In. All rights reserve. 8 ANSYS, In. Proprietary

9 Resulting Log File This is representative of what will go in the omman snippet to represent the table 28 ANSYS, In. All rights reserve. 9 ANSYS, In. Proprietary

10 Voltage Bounary Conitions - Comman Snippets Bottom Layer: Voltage = Volt Snippet for entering a formula in SIMULATION Top Layer: Voltage = 115 [V] sin((2π/.4[s])t) 28 ANSYS, In. All rights reserve. 1 ANSYS, In. Proprietary

11 Piezoeletri Material Data Input Piezoeletri material ata is supplie in ifferent formats Disusse in ANSI/IEEE St , Stanar on Piezoeletriity All inustry stanar material property ata formats are not ompatible with ANSYS Data must be onverte into ANSYS ompatible form Also, material ata is typially supplie with the polarization iretion as Z (or 3), the longituinal iretion as X (or 1), an the transverse iretion as Y (or 2) In our example, the polarization iretion is Y, the longituinal iretion X, an the transverse iretion Z. Thus, the supplie material ata must be transforme appropriately 28 ANSYS, In. All rights reserve. 11 ANSYS, In. Proprietary

12 Introution (ont) For stati or low frequeny evies (e.g., sensors), material property ata are typially provie as Compliane measure uner onstant eletri fiel [s E ], Piezoeletri strain matrix [], an Relative permittivity measure uner onstant stress [ε T ] For higher frequenies evies (e.g., resonators), material property ata are typially provie as Stiffness measure uner onstant eletri fiel [ E ], Piezoeletri stress matrix [e], an Relative permittivity measure uner onstant strain [ε S ] 28 ANSYS, In. All rights reserve. 12 ANSYS, In. Proprietary

13 Require Material Properties For stati analyses, piezoeletri materials are haraterize by Strutural elastiity Piezoeletri oupling Dieletri permittivity For ynami analyses, aitional ata are require Density Strutural amping Dieletri amping Piezoeletri behavior an be efine using ifferent material properties Strutural elastiity Mouli of elastiity Stiffness matrix Compliane matrix Piezoeletri oupling Piezoeletri matrix Dieletri permittivity Relative permittivity Relative permittivity matrix 28 ANSYS, In. All rights reserve. 13 ANSYS, In. Proprietary

14 ANSYS Commans MP Comman Material properties are entere into ANSYS using either the MP (for isotropi or orthotropi properties) or TB ommans (when tabular input is require) TB, LAB, MAT, NTEMP, NPTS, TBOPT, EOSOPT LAB: material moel PIEZ = piezoeletri matrix ANEL = anisotropi elasti matrix TBOPT: options within material moel (stress or strain base) EOSOPT: equation of state TBDATA omman enters the values into the table Defines ata for the table speifie on the last issue TB omman at the temperature speifie on the last issue TBTEMP omman TBDATA, STLOC, C1, C2, C3, C4, C5, C6 STLOC: starting loation C1, C2, C3, C4, C5, C6: ata to be input 28 ANSYS, In. All rights reserve. 14 ANSYS, In. Proprietary

15 Elasti Coeffiients IEEE Stanar 176 speifies stanar 6x6 format for elastiity matrix Row orer is {x, y, z, yz, xz, xy} ANSYS uses the stanar strutural mehanis format Row orer is {x, y, z, xy, yz, xz} Orer of the shear terms is ifferent IEEE Stanar 176 row 4 is equivalent to ANSYS row 5 IEEE Stanar 176 row 5 is equivalent to ANSYS row 6 IEEE Stanar 176 row 6 is equivalent to ANSYS row 4 28 ANSYS, In. All rights reserve. 15 ANSYS, In. Proprietary

16 Elasti Coeffiients (ont) For ANSYS piezoeletri elements to be ompatible with other ANSYS elements, elastiity matries must use onsistent formats Shear rows must be reorere IEEE Stanar 176 Format ANSYS Format ANSYS, In. All rights reserve. 16 ANSYS, In. Proprietary

17 Anisotropi Elasti Coeffiients (ont) Elastiity matrix is input in Stiffness form using TB,ANEL with TBOPT = Input orer is base on position in the matrix C E ANSYS N m 2 TB,ANEL,mati#, TBDATA,1,13.2,7.1,7.3 TBDATA,7,13.2,7.3 TBDATA,12,11.5 TBDATA,16,3 TBDATA,19,2.6 TBDATA,21, ANSYS, In. All rights reserve. 17 ANSYS, In. Proprietary

18 Input Elasti Coeffiients As with stiffness matrix, if elastiity matrix is provie as a ompliane matrix at onstant eletri fiel (s E ) in IEEE Stanar 176 form, it must be onverte to ANSYS format IEEE Stanar 176 format onvert to ANSYS format by rearranging rows s s E IEEE E ANSYS N m 2.6 N m ANSYS, In. All rights reserve. 18 ANSYS, In. Proprietary

19 Input Elasti Coeffiients For this example, in aition to onverting the elastiity ata from the IEEE format to the ANSYS format, it must be also rotate so that the polarization iretion is Y rather than Z s E ANSYS Z ata beomes Y ata Y ata beomes Z ata X ata remains the same N m s E ANSYS Orer for the TBDATA ommans follows the shemati on the right han sie See Comman Snippet for the TBDATA ommans N m 2 28 ANSYS, In. All rights reserve. 19 ANSYS, In. Proprietary

20 Piezoeletri Coeffiients IEEE Stanar 176 uses a stanar textbook 3x6 format for the piezoeletri oupling matrix Orer is {x, y, z, yz, xz, xy} ANSYS uses a 6x3 format for the piezoeletri matrix Orer is {x, y, z, xy, yz, xz} As with elastiity matrix, orer of shear terms is inompatible between IEEE Stanar 176 an ANSYS an must be reorere In aition, rows an olumns are transpose To onvert piezoeletri oeffiient ata provie in the IEEE Stanar 176 format into the ANSYS format Matrix must be transpose Rows 4, 5, an 6 must be appropriately interhange 28 ANSYS, In. All rights reserve. 2 ANSYS, In. Proprietary

21 28 ANSYS, In. All rights reserve. 21 ANSYS, In. Proprietary Piezoeletri Coeffiients (ont) Typial Piezoeletri Matrix Transpose Piezoeletri Matrix ANSYS Piezoeletri Matrix Transpose Piezoeletri Matrix

22 Piezoeletri Coeffiients Piezoeletri oeffiients are provie in stress form in IEEE Stanar 176 format To onvert to ANSYS format, first transpose the matrix T IEEE N C Then rearrange rows 4, 5, & ANSYS, In. All rights reserve. 22 ANSYS, In. Proprietary ANSYS, Z 1.5

23 Piezoeletri Coeffiients Finally, Y being the iretion of polarization instea of Z must be aounte for Piezoeletri oeffiients in the stress form are input using TB,PIEZ with TBOPT = Input orer is base on position in matrix ANSYS, Z ANSYS,Y x y z xy yz zx x y z x z y xz zy yx x z y See Comman Snippet for TBDATA ommans 28 ANSYS, In. All rights reserve. 23 ANSYS, In. Proprietary

24 Piezoeletri Material Define - Comman Snippets Couple Element 226 Anisotropi Elasti matrix Piezoeletri matrix 28 ANSYS, In. All rights reserve. 24 ANSYS, In. Proprietary

25 Piezoeletri Solution Stati SPARSE is the reommene solver Transient SPARSE is the reommene solver reommene TINTP (transient algorithm) settings ALPHA =.25 DELTA =.5 THETA =.5 Moal Blok Lanzos is the reommene solver Harmoni SPARSE is the reommene solver harmonially varying isplaement proues a urrent applie urrent proues a vibration 28 ANSYS, In. All rights reserve. 25 ANSYS, In. Proprietary

26 Eletri Potential 28 ANSYS, In. All rights reserve. 26 ANSYS, In. Proprietary

27 Blae Movements t=.1 Se t=.3 Se Displaement Exaggerate an Not to Sale Equivalent stresses 28 ANSYS, In. All rights reserve. 27 ANSYS, In. Proprietary

28 CFX Moel Flow omain internal bounary is the evie. Blue arrows represent Opening Conition Flui may move in an out suh bounaries 28 ANSYS, In. All rights reserve. 28 ANSYS, In. Proprietary

29 CFX Setup Flow omain Default is the FSI bounary Fore Displaement transfers 28 ANSYS, In. All rights reserve. 29 ANSYS, In. Proprietary

30 CFX Setup In some ases, the MFX two way proeure is mae more robust with the use of an Impliit form of Artifiial Compressibility This is implemente by setting up a zero flui mass soure on the FSI bounary an using a Total Mass Soure Pressure Coeffiient as shown 28 ANSYS, In. All rights reserve. 3 ANSYS, In. Proprietary

31 Blae Displaement at.1 se ANSYS CFX 28 ANSYS, In. All rights reserve. 31 ANSYS, In. Proprietary

32 Blae Displaements at.3 se ANSYS CFX 28 ANSYS, In. All rights reserve. 32 ANSYS, In. Proprietary

33 Veloity Contours in CFX Time =.1 se..2 se..3 se..4 se. 28 ANSYS, In. All rights reserve. 33 ANSYS, In. Proprietary

34 Summary Demonstrate the Multiphysis analysis of a piezo-eletri fan with ANSYS an CFX in the MFX Solver The Workbenh platform is shown to be flexible enough to hanle non-native appliations Proeures exist to easily onvert the piezoeletri property ata to the ANSYS format The robustness of Two-Way FSI oupling is enhane with artifiial ompressibility 28 ANSYS, In. All rights reserve. 34 ANSYS, In. Proprietary