Modal analysis and partecipatign ratio

AndreaC91AndreaC91
I'm trying to carry out a modal analysis of a structure made of beam and plate elements. I have already obtained the natural frequencies but I'm now wondering if Mecway allows to calculate the modal mass partecipating ratios for each mode.

Thanks,
Andrea

Comments

  • JohnMJohnM
    Run in CCX, look at output files, I think you may find what you need.

    https://mecway.com/forum/discussion/1025/modal-vibration-3d
  • prop_designprop_design
    edited June 2022
    If you are using CCX, you can find the following info in the *.dat file:

    E I G E N V A L U E O U T P U T

    MODE NO EIGENVALUE FREQUENCY
    REAL PART IMAGINARY PART
    (RAD/TIME) (CYCLES/TIME (RAD/TIME)

    1 0.8390526E+05 0.2896640E+03 0.4610147E+02 0.0000000E+00
    2 0.8391433E+05 0.2896797E+03 0.4610396E+02 0.0000000E+00
    3 0.5512280E+06 0.7424473E+03 0.1181642E+03 0.0000000E+00
    4 0.5516372E+06 0.7427228E+03 0.1182080E+03 0.0000000E+00
    5 0.1944621E+07 0.1394497E+04 0.2219410E+03 0.0000000E+00
    6 0.1946785E+07 0.1395272E+04 0.2220645E+03 0.0000000E+00
    7 0.3960162E+07 0.1990016E+04 0.3167208E+03 0.0000000E+00
    8 0.3960404E+07 0.1990076E+04 0.3167305E+03 0.0000000E+00
    9 0.5876384E+07 0.2424125E+04 0.3858116E+03 0.0000000E+00
    10 0.5878300E+07 0.2424521E+04 0.3858744E+03 0.0000000E+00
    11 0.7892330E+07 0.2809329E+04 0.4471186E+03 0.0000000E+00
    12 0.7895262E+07 0.2809851E+04 0.4472017E+03 0.0000000E+00
    13 0.1726901E+08 0.4155600E+04 0.6613842E+03 0.0000000E+00
    14 0.1729721E+08 0.4158991E+04 0.6619240E+03 0.0000000E+00
    15 0.2104282E+08 0.4587246E+04 0.7300828E+03 0.0000000E+00
    16 0.2104766E+08 0.4587773E+04 0.7301668E+03 0.0000000E+00
    17 0.3086707E+08 0.5555814E+04 0.8842353E+03 0.0000000E+00
    18 0.3094685E+08 0.5562989E+04 0.8853773E+03 0.0000000E+00
    19 0.3889258E+08 0.6236392E+04 0.9925526E+03 0.0000000E+00
    20 0.3891166E+08 0.6237921E+04 0.9927960E+03 0.0000000E+00

    P A R T I C I P A T I O N F A C T O R S

    MODE NO. X-COMPONENT Y-COMPONENT Z-COMPONENT X-ROTATION Y-ROTATION Z-ROTATION

    1 -0.2720479E-01 0.2605309E+00 -0.1612773E+01 -0.3360309E-01 0.2352765E+00 0.1460069E+01
    2 0.1706726E+00 -0.1634563E+01 -0.2571631E+00 0.2107912E+00 -0.1475562E+01 0.2328573E+00
    3 -0.2112369E-01 0.1609956E+00 0.2096349E+00 -0.1499918E-01 -0.1658846E-01 -0.1613380E+01
    4 0.2991901E+00 -0.2276897E+01 0.1478210E-01 0.2122181E+00 0.2351388E+00 -0.1141795E+00
    5 0.8555255E-03 -0.1009717E-01 -0.1015959E+01 0.2434534E-03 0.5879486E-02 -0.1117842E+01
    6 -0.1343981E+00 0.1689704E+01 -0.6062664E-02 -0.4046722E-01 -0.9546351E+00 -0.6836879E-02
    7 0.2419247E+00 -0.8097142E-01 -0.1086501E+01 0.9951712E-01 -0.9065159E+00 -0.1548650E+00
    8 -0.1908563E+00 0.6407194E-01 -0.1376550E+01 -0.7853967E-01 0.7153224E+00 -0.1959894E+00
    9 0.2138500E-01 0.5708599E-01 -0.1207198E+01 0.1756586E-01 -0.8243791E-01 -0.4091105E+00
    10 -0.2053191E+00 -0.5470218E+00 -0.1257587E+00 -0.1688549E+00 0.7919456E+00 -0.4261783E-01
    11 0.1348559E+00 -0.2795495E+00 -0.1106301E+01 0.6479987E-01 -0.1545806E+00 0.2683080E+00
    12 -0.4957035E+00 0.1026792E+01 -0.3010554E+00 -0.2381408E+00 0.5679981E+00 0.7299830E-01
    13 0.5186416E-01 -0.1667556E+00 -0.3420819E-02 0.1993517E-01 0.8457660E-02 0.4292614E+00
    14 -0.3798697E+00 0.1214103E+01 -0.6028701E-03 -0.1458152E+00 -0.6143391E-01 0.5907253E-01
    15 0.1321420E+00 0.2033892E+00 -0.5258879E+00 0.9620336E-01 -0.2223979E+00 -0.1059341E+00
    16 -0.1403058E+00 -0.2163954E+00 -0.4946892E+00 -0.1021690E+00 0.2361640E+00 -0.9989290E-01
    17 -0.7480601E-02 0.2388227E-01 -0.1334235E+01 -0.1010582E-02 -0.1195809E-01 -0.4621756E+00
    18 -0.3803811E+00 0.1171401E+01 0.2760411E-01 -0.4797618E-01 -0.6051167E+00 0.9386340E-02
    19 -0.1432703E+00 -0.4575675E-01 0.4455106E+00 -0.1803580E+00 0.5474655E+00 0.2334144E-01
    20 -0.4403464E-01 -0.1382175E-01 -0.1461632E+01 -0.5492541E-01 0.1657235E+00 -0.7661719E-01

    E F F E C T I V E M O D A L M A S S

    MODE NO. X-COMPONENT Y-COMPONENT Z-COMPONENT X-ROTATION Y-ROTATION Z-ROTATION

    1 0.7401009E-03 0.6787634E-01 0.2601038E+01 0.1129167E-02 0.5535504E-01 0.2131801E+01
    2 0.2912912E-01 0.2671796E+01 0.6613284E-01 0.4443293E-01 0.2177285E+01 0.5422253E-01
    3 0.4462102E-03 0.2591957E-01 0.4394680E-01 0.2249754E-03 0.2751769E-03 0.2602996E+01
    4 0.8951473E-01 0.5184260E+01 0.2185105E-03 0.4503652E-01 0.5529027E-01 0.1303695E-01
    5 0.7319239E-06 0.1019528E-03 0.1032173E+01 0.5926955E-07 0.3456836E-04 0.1249572E+01
    6 0.1806284E-01 0.2855099E+01 0.3675589E-04 0.1637596E-02 0.9113281E+00 0.4674292E-04
    7 0.5852756E-01 0.6556371E-02 0.1180484E+01 0.9903657E-02 0.8217710E+00 0.2398318E-01
    8 0.3642612E-01 0.4105213E-02 0.1894890E+01 0.6168480E-02 0.5116862E+00 0.3841184E-01
    9 0.4573182E-03 0.3258810E-02 0.1457327E+01 0.3085595E-03 0.6796008E-02 0.1673714E+00
    10 0.4215591E-01 0.2992329E+00 0.1581524E-01 0.2851197E-01 0.6271778E+00 0.1816279E-02
    11 0.1818610E-01 0.7814794E-01 0.1223902E+01 0.4199024E-02 0.2389518E-01 0.7198920E-01
    12 0.2457220E+00 0.1054302E+01 0.9063434E-01 0.5671105E-01 0.3226219E+00 0.5328751E-02
    13 0.2689891E-02 0.2780745E-01 0.1170201E-04 0.3974109E-03 0.7153201E-04 0.1842653E+00
    14 0.1443010E+00 0.1474047E+01 0.3634523E-06 0.2126208E-01 0.3774125E-02 0.3489564E-02
    15 0.1746150E-01 0.4136719E-01 0.2765581E+00 0.9255087E-02 0.4946083E-01 0.1122203E-01
    16 0.1968571E-01 0.4682697E-01 0.2447174E+00 0.1043850E-01 0.5577345E-01 0.9978592E-02
    17 0.5595940E-04 0.5703630E-03 0.1780184E+01 0.1021276E-05 0.1429960E-03 0.2136063E+00
    18 0.1446898E+00 0.1372181E+01 0.7619870E-03 0.2301714E-02 0.3661662E+00 0.8810338E-04
    19 0.2052639E-01 0.2093680E-02 0.1984797E+00 0.3252900E-01 0.2997185E+00 0.5448228E-03
    20 0.1939049E-02 0.1910409E-03 0.2136367E+01 0.3016800E-02 0.2746428E-01 0.5870194E-02
    TOTAL 0.8907180E+00 0.1521574E+02 0.1424368E+02 0.2774656E+00 0.6316088E+01 0.6789640E+01

    T O T A L E F F E C T I V E M A S S

    MODE NO. X-COMPONENT Y-COMPONENT Z-COMPONENT X-ROTATION Y-ROTATION Z-ROTATION

    0.7827053E+02 0.7821689E+02 0.7889396E+02 0.2095702E+01 0.8865407E+01 0.8550270E+01

    These are deleted if you close the model. So you have to look in the 'Temp' folder where CCX is saving the solve. In my case it's in the user, app data, local, temp folder. The folder name will be a somewhat random name with Mecway in it. If you have did several solves there can be several folders. You have to poke around to find the right file.
  • AndreaC91AndreaC91
    edited June 2022
    Thanks for your answers.
    Is there no output file to be checked in case I use the Internal solver?
    Is there no way of calculating the mass partecipation factors with the Internal solver?

    By the way, I get completely different natural frequencies by running the Internal solver or CCX solver.
    Please find attached the file for your reference.
  • VictorVictor
    edited June 2022
    Regarding different modes between solvers, refine the mesh and they match. Mesh refinement is the solution to most errors in FEA.

    No mass participation factors for the internal solver, sorry.
  • AndreaC91AndreaC91
    The mesh in the attached file is a pretty standard one I've already used with other FEA softwares. By the way, with this mesh the internal solver provides very close frequencies with respect to the ones I got with another software.

    I've tried to double the numbers of elements (which I fell unpractical for this kind of structure) but the CCX solver still provides completely different results.
    Did you get similar frequencies with a refined mesh? If yes, how refined is the mesh?

    Thanks,
  • VictorVictor
    The CCX beams being solids can require refinement where traditional beam elements may give an exact solution with a single element.

    This picture shows the close match I see after refining




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