Natural Frequaency Analysis - Mass Participation Factor 1

[Srki1982]

Hello,

I am trying to find a way to extract the mass participation factor from the Normal Modes/Eigenvalue Analysis for different natural frequencies. I receive 10 modes with frequencies and I need to see if the first frequency is dominating by checking if the mass participation is minimum 90 %.
I have tried to enable the "Summary" and "Modal Participation Factors" in the NASTRAN XY Output Modal Analysis Output Requests and chosed a reference node (is it required ?). How can I calculate or find the mass participation factor for each frequency? I have opened the file xxxxxx.f06 and I can see at the end of the file following information, but I don't know how to interpret this correclty (it should be 0.9 < mass participation < 1):


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

TOTAL EFFECTIVE MASS FRACTION
REFERENCE POINT AT ORIGIN OF BASIC COORDINATE SYSTEM


T1 T2 T3 R1 R2 R3
3.818382E-01 3.819357E-01 8.221074E-02 5.752988E-01 3.228863E-01 3.785327E-01




EFFECTIVE MASS MATRIX
*** ***
* 1.443387E-01 3.651784E-03 -1.024220E-02 -2.381894E+00 1.155805E+02 -4.732883E+01 *
* 3.651784E-03 1.443069E-01 4.299510E-03 -1.204771E+02 -4.921949E-04 -1.045348E+02 *
* -1.024220E-02 4.299510E-03 3.101931E-02 9.204855E+00 2.176511E+01 -2.006953E-01 *
* -2.381894E+00 -1.204771E+02 9.204855E+00 1.151057E+05 8.755245E+03 8.790510E+04 *
* 1.155805E+02 -4.921949E-04 2.176511E+01 8.755245E+03 1.286155E+05 -3.808336E+04 *
* -4.732883E+01 -1.045348E+02 -2.006953E-01 8.790510E+04 -3.808336E+04 1.394250E+05 *
*** ***

A-SET RIGID BODY MASS MATRIX
*** ***
* 3.780101E-01 0.000000E+00 0.000000E+00 0.000000E+00 1.250144E+02 -1.395959E+02 *
* 0.000000E+00 3.778304E-01 0.000000E+00 -1.250226E+02 0.000000E+00 -2.767815E+02 *
* 0.000000E+00 0.000000E+00 3.773146E-01 1.393326E+02 2.767366E+02 0.000000E+00 *
* 0.000000E+00 -1.250226E+02 1.393326E+02 2.000798E+05 1.011640E+05 9.113691E+04 *
* 1.250144E+02 0.000000E+00 2.767366E+02 1.011640E+05 3.983307E+05 -4.281954E+04 *
* -1.395959E+02 -2.767815E+02 0.000000E+00 9.113691E+04 -4.281954E+04 3.683300E+05 *
*** ***

1 LOAD CONDITION 5: NATURAL FREQUENCY ANALYSIS APRIL 16, 2013 NX NASTRAN 1/24/13 PAGE 25055

0

MODAL PARTICIPATION FACTORS

MODE FREQUENCY T1 T2 T3 R1 R2 R3
NO.

1 2.141795E+01 -1.172308E-02 3.375057E-01 -6.450092E-03 -3.191174E+02 -1.879256E+01 -3.099261E+02
2 3.098532E+01 -2.464878E-01 -9.047390E-02 -6.103943E-03 7.929072E+01 -2.312487E+02 -4.555993E+00
3 3.355923E+01 -2.637012E-01 6.451740E-02 -5.132771E-03 -6.460348E+01 -2.492967E+02 1.778659E+02
4 4.458456E+01 1.063708E-02 -1.492380E-02 1.102647E-02 1.615704E+01 2.963749E+01 -4.103033E+01
5 5.547067E+01 1.028126E-02 -5.272186E-04 -4.136376E-03 -1.803132E+01 5.883485E+00 8.463337E-03
6 7.324319E+01 -9.173676E-03 -5.452555E-02 1.245523E-02 1.794196E+01 9.677306E+00 4.780940E+01
7 8.605404E+01 1.940518E-02 -3.057752E-02 -1.186010E-03 1.479761E+01 1.121702E+01 -5.887019E+00
8 9.510368E+01 -1.492823E-02 1.013157E-01 1.326378E-01 2.153884E+01 7.332193E+01 -6.277428E+01
9 1.065708E+02 -3.781700E-02 -5.778564E-02 8.814560E-02 2.697997E+01 6.770162E+01 5.433641E+01
10 1.082683E+02 -1.075832E-01 -1.771199E-02 7.250129E-02 2.214056E+01 3.931290E+01 2.858033E+01

 

[BlasMolero]

Hello!,
In the Output Request of the Modal Analysis (SOL103) simply select the first one SUMMARY and the last one MODAL EFFECTIVE MASS FRACTION:

After performing the Modal Analysis (SOL103) you will see in FEMAP different functions created of MASS FRACTION and MASS SUM in the three axis X,Y,Z, then simply plot them and you will have the mass accumulated mode by mode in each direction (SUM MASS) and also the fraction mass mode by mode ( MASS FRAC), is so easy:

Best regards,
Blas.

~~~~~~~~~~~~~~~~~~~~~~
Blas Molero Hidalgo
Ingeniero Industrial
Director

IBERISA
48011 BILBAO (SPAIN)
WEB:

http://www.iberisa.com

Blog de FEMAP & NX Nastran:

http://iberisa.wordpress.com/

 

[Srki1982]

Thank you Blas!

I did not see that after the analysis FEMAP generates functions for this.

Best regards

 

[BlasMolero]

Hello!,
I run FEMAP V11 & NX NASTRAN 8.5, maybe FEMAP with other solvers do not generate the mass participation functions. This is not a problema of FEMAP, but the FEA solver you use, then let us know the name of the FEA solver you run.
Best regards,
Blas.

~~~~~~~~~~~~~~~~~~~~~~
Blas Molero Hidalgo
Ingeniero Industrial
Director

IBERISA
48011 BILBAO (SPAIN)
WEB:

http://www.iberisa.com

Blog de FEMAP & NX Nastran:

http://iberisa.wordpress.com/

 

[Srki1982]

Hello Blas,

I run the same version as you so there is no problems
I just meant that I didn't see that FEMAP generates the functions automatically. I can see that now so there is no more problems. Thank you

Best regards