Is there any problems with ERR % -99.9 when rayleigh damping is applied?

gslee
gslee New Altair Community Member
edited October 2020 in Community Q&A

Hi,

 

I applied rayleigh damping using /DAMP

 

Result is as follows.

 

 NC=       0 T= 0.0000E+00 DT= 6.0221E-07 ERR=  0.0% DM/M= 0.0000E+00

 

 NC=     500 T= 2.2232E-04 DT= 4.4566E-07 ERR=-32.8% DM/M= 0.0000E+00
 ELAPSED TIME=          2.12 s  REMAINING TIME=      19105.88 s

 

 NC=    1000 T= 4.4058E-04 DT= 4.3447E-07 ERR=-37.1% DM/M= 0.0000E+00
 ELAPSED TIME=          2.55 s  REMAINING TIME=      11554.85 s

 

 NC= 4673500 T= 1.9996E+00 DT= 4.4771E-07 ERR=-99.9% DM/M= 0.0000E+00
 ELAPSED TIME=       4238.97 s  REMAINING TIME=          0.82 s

 

 NC= 4674000 T= 1.9998E+00 DT= 4.4771E-07 ERR=-99.9% DM/M= 0.0000E+00
 ELAPSED TIME=       4239.43 s  REMAINING TIME=          0.34 s
     

 

Because of damping, 

Does this result seem to be no problem?

image.png.b6d5a64fac5bb77d38b7c92d500fe0f7.png

 

 

 

Thanks

 

 

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Answers

  • Crashphys
    Crashphys Altair Community Member
    edited August 2019

    Negative energy error can be reasonable depending on your model. A negative energy error makes sense when you have things like friction or damping. What I think may be happening is your damping is so high it is absorbing all the energy, so double check your values for damping.

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