Want on obtain vibration transmissibility
rahull roy
James M. Kennedy
Dear Rahull,
See if these presentations can serve as some help.
This paper introduced a set of new features of LS-DYNA for solving frequency domain vibration and acoustic problems. They included random vibration and fatigue analysis, frequency response function, steady state dynamics, response spectrum analysis and BEM/FEM acoustics. Some examples were given to illustrate how to use these features. The objective of implementing these features was to provide users the capabilities to deal with frequency domain vibration and acoustic problems, which are very common in auto and aerospace industries and many other industries:
Huang, Y., Souli, M., Ashcraft, C., Grimes, R., Wang, J., Rassaian, M., and Lee, H.-C., "Development of Frequency Domain Dynamic and Acoustic Capabilities in LS-DYNA", 8th European LS-DYNA Users Conference, Strasbourg, France, May, 2011.
http://www.dynalook.com/8th-european-ls-dyna-conference/session-23/Session23_Paper3.pdf
Benchmark solutions were provided showing how LS-DYNA handles the basic linear normal modes analyses using standard finite elements (beams, plates, solids and rigid links) with a comparison to an industry standard Nastran solver:
Laird, G. "Large Scale Normal Modes and PSD Analysis with Nastran and LS-DYNA", 12th International LS-DYNA Users Conference, Dearborn, Michigan, June, 2012.
https://www.dynalook.com/international-conf-2012/simulation10-f.pdf
A large composite shipping container was analyzed for drop, impact, PSD random vibration and general stress analysis. The main shell of the container was a glass-fiber vacuum infused composite with closures made of aluminum. The progressive composite failure was modeled using *MAT_054 (multiple sets of fiberglass data included). The Mortar contact was used for both implicit and explicit simulations:
Jensen, A., Laird, G., and Tayne, A., "Broad-Spectrum Stress and Vibration Analysis of Large Composite Container", 14th International LS-DYNA Users Conference, Dearborn, Michigan, June, 2016.
Presentation regarding FRF (frequency response function), SSD (steady state dynamics), random vibration analysis, response spectrum analysis, and modal transient analysis vibration solvers; BEM, FEM, and SEA for high frequency acoustic solvers; and frequency and time domain fatigue solvers:
Huang, Y., and Cui, Z., "Vibration, Acoustic and Fatigue Solvers", NVH Analysis, DYNAmore GmbH, Stuttgart, Germany, October, 2017.
https://www.dynamore.de/en/downloads/infodays/dokumente/2017-nvh-frequency-domain-fatigue/nvh-frequency-domain-fatigue-en/Infoday_Acoustic_20171010.pdf
Sincerely,
James M. Kennedy
KBS2 Inc.
March 5, 2021
p.s.
Mondal, P. and Arunachalam, S., “Finite Element Modelling of Car Seat with Hyperelastic and Viscoelastic Foam Material Properties to Assess Vertical Vibration in Terms of Acceleration”, Engineering, Vol.12, pp. 177-193, 2020.
https://www.scirp.org/html/3-8103407_99015.htm
Dorugade, D.V., Rakheja, S. and Boileau, P.E., “Modeling and Validation of Static and Dynamic Seat Cushion Characteristics”, 12th European LS-DYNA Conference, Koblenz, Germany, May 2019.
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rahull roy
James M. Kennedy
Dear Rahul,
Please take a look at the examples found here:
https://ftp.lstc.com/anonymous/outgoing/huang/examples/random.vibration.fatigue/
I would thing that you could remove the FATIGUE components and you should have
the base DOMAIN_RANDOM_VIBRATION input/output:
*FREQUENCY_DOMAIN_RANDOM_VIBRATION_{OPTION}
Available options include:
<BLANK>, FATIGUE
Purpose: Set random vibration control options. When the FATIGUE keyword option is
used, compute fatigue life of structures or parts under random vibration (see Remark 2).
2. Fatigue. MSTRES must be set to 1 in the keyword *CONTROL_IMPLICIT_-
EIGENVALUE for the FATIGUE keyword option because the fatigue analysis
is depends on stresses.
-----------------------------------------
I believe that you could modify this entry plus remove other various cards involving
FATIGUE option (from one of the examples cited in above link):
$*FREQUENCY_DOMAIN_RANDOM_VIBRATION_FATIGUE
*FREQUENCY_DOMAIN_RANDOM_VIBRATION
$# mdmin mdmax fnmin fnmax restrt restrm
1 15 0. 90000.
$# dampf lcdam lctyp dmpmas dmpstf dmptyp
0.03
$# vaflag method unit umlt vapsd varms npsd nftg
1 1 0 1 1
$# ldtyp ipanelu ipanelv temper dsflag
$# sid stype dof ldpsd ldvel ldflw ldspn cid
3 2001
$# mftg nftg sntype texpos strsf inftg
$ 1 1 1.44e+7
$# pid lcid ptype ltype a b sthres snlimt
$ 4075 -1 1.e+06 3 2
$ 4075 100
*DATABASE_FREQUENCY_BINARY_D3PSD
$# binary
1
$# fmin fmax nfreq fspace lcfreq
0.100 2.000 5
*DATABASE_FREQUENCY_BINARY_D3RMS
$# binary
1
$*DATABASE_FREQUENCY_BINARY_D3FTG
$# binary
$ 1
-----------------------------------------
Sincerely,
James M. Kennedy
KBS2 Inc.
March 5, 2021
From: ls-d...@googlegroups.com [mailto:ls-d...@googlegroups.com] On Behalf Of rahull roy
Sent: Friday, March 05, 2021 3:30 PM
To: LS-DYNA2 <ls-d...@googlegroups.com>
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