Time Domain Fatigue Analysis
tevfik...@gmail.com
l...@schwer.net
You need to include the keyword *DATABASE_D3FTG and associated parameters.
--len
From: ls-d...@googlegroups.com <ls-d...@googlegroups.com> On Behalf Of tevfik...@gmail.com
Sent: Thursday, October 13, 2022 7:59 AM
To: LS-DYNA2 <ls-d...@googlegroups.com>
Subject: [LS-DYNA2] Time Domain Fatigue Analysis
Hi all
I want to perform time domain fatigue analysis but when I performed this there weren't any steps for df3ftg file. Can you help me please?
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tevfik...@gmail.com
l...@schwer.net
Download the keyword manual and have a look.
https://ftp.lstc.com/anonymous/outgoing/jday/manuals/LS-DYNA_Manual_Volume_I_R13.pdf
--len
From: ls-d...@googlegroups.com <ls-d...@googlegroups.com> On Behalf Of tevfik...@gmail.com
Sent: Thursday, October 13, 2022 8:18 AM
To: LS-DYNA2 <ls-d...@googlegroups.com>
Subject: Re: [LS-DYNA2] Time Domain Fatigue Analysis
I added *DATABASE_D3FTG and then I got an error. You mentioned about associated parameters. What was these? I am beginner level user.
13 Ekim 2022 Perşembe tarihinde saat 18:06:09 UTC+3 itibarıyla L...@Schwer.net şunları yazdı:
You need to include the keyword *DATABASE_D3FTG and associated parameters.
--len
From: ls-d...@googlegroups.com <ls-d...@googlegroups.com> On Behalf Of tevfik...@gmail.com
Sent: Thursday, October 13, 2022 7:59 AM
To: LS-DYNA2 <ls-d...@googlegroups.com>
Subject: [LS-DYNA2] Time Domain Fatigue Analysis
Hi all
I want to perform time domain fatigue analysis but when I performed this there weren't any steps for df3ftg file. Can you help me please?
--
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Tevfik Melhem
Tevfik MELHEM
Makina Mühendisi
James M. Kennedy
Dear Tevfik,
This paper reviews the recent development in fatigue solvers in LS-DYNA. Fatigue analysis is critical to the design and safety evaluation of metal structures and components. Both frequency domain and time domain fatigue solvers have been implemented to LS-DYNA, to meet the requirements of users from different industry areas. Examples are provided in this paper, to illustrate how to use these fatigue solvers for real problems and do post-processing on the results. The plan on future development of the fatigue solvers in LS-DYNA, is also discussed.
Huang, Y., and Cui, Z., “Recent Updates in Fatigue Analysis with LS-DYNA”, Livermore Software Technology Corporation; Livermore, California, February, 2028.
Tabiei, A., and Zhang, W., "Fatigue Life Prediction of Composite Adhesive Joints using LS-DYNA", 15th International LS-DYNA Users Conference, Dearborn, Michigan, June, 2018.
LS-DYNA was employed in the numerical simulation of clinching. A modal analysis for the cantilevered clinched joints analyzing the influence of parameter combination of different elastic modulus, density and Poisson's ratio on natural frequency:
Feng, M.-S., "Study of Fatigue Properties of Clinched Joint", Master's Thesis, Mechanical Manufacturing and Automation, China, May, 2012.
http://www.globethesis.com/?t=2211330368981162
http://www.eng-paper.com/study-of-fatigue-properties-of-clinched-joint/
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
A new feature of random vibration fatigue analysis has been implemented to LS-DYNA, to perform the structural fatigue analysis in random vibration environment. This feature computes accumulative damage ratio and expected fatigue life for structures, based on the Palmgren-Miner's role of cumulative damage ratio and material's S-N fatigue curve:
Ringeval, A., and Huang, Y., "Random Vibration Fatigue Analysis with LS-DYNA", 12th International LS-DYNA Users Conference, Dearborn, Michigan, June, 2012.
https://www.dynalook.com/international-conf-2012/simulation10-d.pdf
This paper introduced a new feature of LS-DYNA for solving frequency domain random vibration fatigue. The feature provided cumulative damage ratio calculation and fatigue life prediction for structures subjected to random vibration excitations based on various theories. Dirlik method which has been long considered to be one of the best methods was demonstrated. The service life for UAV landing gear was predicted using this new feature:
Al-Bahkali, E., Elkenani, H, and Souli, M., "NVH and Random Vibration Fatigue Analysis of a Landing Gear’s Leg for an Un-Manned Aerial Vehicle Using LS-DYNA", 9th European LS-DYNA Users Conference, Manchester, United Kingdom, May, 2013.
A number of frequency domain features (frequency response function, steady state dynamics, random vibration and fatigue, acoustic analysis by BEM/FEM, and response spectrum analysis) have been implemented towards NVH, durability analysis of vehicles and other vibration and acoustic analysis:
Huang, Y., and Cui, Z., "New Frequency Domain Feature in LS-DYNA", 2013 Developer Forum, Stuttgart-Filderstadt, Germany, September, 2013.
A series of frequency domain features have been implemented to LS-DYNA since version 971 R6 to perform vibration, acoustic and fatigue analysis for users from various industries:
Huang, Y., and Cui, Z., "Updated Frequency Domain Analysis in LS-DYNA", 13th German LS-DYNA Form, Bamberg, Germany, October, 2014.
New features for BEM and FEM acoustic analysis plus fatigue analysis were presented:
Huang, Y., and Cui, Z., "Frequency Domain Analysis in LS-DYNA", 2nd China LS-DYNA Users’ Conference, Shanghai, China, November, 2015.
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.
*MAT_ADD_FATIGUE
The ADD_FATIGUE option defines the S-N fatigue property of a material model.
Fatigue analysis based on SSD
This is a simplified bumper model with base acceleration. It shows how to fatigue analysis for sine sweep testing with *FREQUENCY_DOMAIN_SSD_FATIGUE and how to postprocess with *DATABASE_FREQUENCY_BINARY_D3SSD and *DATABASE_FREQUENCY_BINARY_D3FTG. Example 5.5 from LS-Dyna training class NVH, Fatigue and Frequency Domain Analysis with LS-DYNA by Yun Huang.
Fatigue analysis based on SSD — Welcome to LS-DYNA Examples
LS-DYNA Tutorial | Fatigue Life estimation of Rocket nozzle subjected to Power Spectrum Density load
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Please take a look at the examples found here:
https://ftp.lstc.com/anonymous/outgoing/huang/examples/random.vibration.fatigue/
I would think 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.
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Sincerely,
James M. Kennedy
KBS2 Inc.
October 13, 2022
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