• Fatigue Analysis Force-Time history

    Younghoon KIM
    Younghoon KIM
    Hi, I try to conduct fatigue analysis by using SACS. With very useful answer in the communities, fatigue analysis was successful. However, I also want to conduct a fatigue experiment for some members based on results from fatigue analysis by SACS…
    • Answered
    • over 6 years ago
    • MAXSURF | MOSES | SACS | OpenWindPower
    • MAXSURF | MOSES | SACS | OpenWindPower Forum
  • RE: Can we use load RAOs to generate common solution file with inertia loads for fatigue analysis. If yes, how it can be done?

    Geoff McDonald
    Geoff McDonald
    Anupam, Let's first look at the input requirements for a tow fatigue analysis: Fatigue Input File (ftginp) Common Solution File (saccsf) Seastate Input File or Tow Input File (towinp) The fatigue input file defines the fatigue cases which…
    • over 6 years ago
    • MAXSURF | MOSES | SACS | OpenWindPower
    • MAXSURF | MOSES | SACS | OpenWindPower Forum
  • RE: USER DEFINED SCF FOR TUBULAR CONNECTION

    Geoff McDonald
    Geoff McDonald
    C.karthikeyan, You can specify SCF overrides in a variety of ways in your fatigue input file, the most common being the SCF line and the CONSWF for plate girders. The SCF line can be used to override SCF's for all plate girder connections whereas the…
    • over 6 years ago
    • MAXSURF | MOSES | SACS | OpenWindPower
    • MAXSURF | MOSES | SACS | OpenWindPower Forum
  • RE: How to perform spectral fatigue analysis using SACS

    Geoff McDonald
    Geoff McDonald
    Stephen, You need to do a Tow Fatigue analysis. Tow Fatigue will analyze fatigue damage of a structure by generating transfer functions using motion RAO's (Velocity, Motion or Acceleration RAO's) and combining those transfer functions with the wave…
    • over 6 years ago
    • MAXSURF | MOSES | SACS | OpenWindPower
    • MAXSURF | MOSES | SACS | OpenWindPower Forum
  • RE: Wave spreading application

    Geoff McDonald
    Geoff McDonald
    Sanjay, That is not how the wave spreading works in SACS. When you select the wave spreading option, SACS will take the load cases from +- 90 degrees from the fatigue load case direction and factor those load cases using cos^n(theta) so that total equivalent…
    • over 6 years ago
    • MAXSURF | MOSES | SACS | OpenWindPower
    • MAXSURF | MOSES | SACS | OpenWindPower Forum
  • RE: SACS - Morison Drag Linearisation for Frequency Domain Analysis

    Geoff McDonald
    Geoff McDonald
    Kasiphon, The nonlinear drag component in spectral wave fatigue analyses is addressed by using constant steepness waves when generating transfer functions. See Section 16.7.2.3 of ISO 19902. Regards, Geoff
    • over 7 years ago
    • MAXSURF | MOSES | SACS | OpenWindPower
    • MAXSURF | MOSES | SACS | OpenWindPower Forum
  • RE: SACS Broad-Band Random Process

    Geoff McDonald
    Geoff McDonald
    Kasiphon, The broad band option in SACS utilizes the equations presented in Application of computers in fatigue analysis ( Dirlik 1985). Dirlik uses an empirical formula to calculate the rainflow range density for various sea-states including double…
    • over 7 years ago
    • MAXSURF | MOSES | SACS | OpenWindPower
    • MAXSURF | MOSES | SACS | OpenWindPower Forum
  • RE: SACS - how to display fatigue lives via labelling in v10.1

    Geoff McDonald
    Geoff McDonald
    Sam, I would definitely rerun the fatigue analysis in the new version if you are using the fatigue extract file with the new viewer. I believe there is some additional information that is saved to the fatigue extract file which may cause errors in Precede…
    • over 7 years ago
    • MAXSURF | MOSES | SACS | OpenWindPower
    • MAXSURF | MOSES | SACS | OpenWindPower Forum
  • RE: Thickness Reference (tref) in SACS Built-in S-N Curve

    Geoff McDonald
    Geoff McDonald
    Kasiphon, When selecting the NT option for the Norsok 'T' SN curve, SACS actually uses the 3.2 cm minimum thickness instead of the 2.5 cm minimum output (See below). There is currently no way to override the minimum thickness used for thickness correction…
    • over 7 years ago
    • MAXSURF | MOSES | SACS | OpenWindPower
    • MAXSURF | MOSES | SACS | OpenWindPower Forum
  • Thickness Reference (tref) in SACS Built-in S-N Curve

    Kasiphon Kurojjanawong
    Kasiphon Kurojjanawong
    Dear Sir, Do we have any command to change thickness reference in built-in S-N curve in SACS? For example, Thickness reference for tubular connection should be 32mm for DNVGL-RP-0005 (2014) S-N "T" Curve. However, SACS used tref = 25mm for…
    • over 7 years ago
    • MAXSURF | MOSES | SACS | OpenWindPower
    • MAXSURF | MOSES | SACS | OpenWindPower Forum
  • RE: DNVGL-RP-0005 (2014) : Reduction factor for root stress of single-sided welded in tubular joints

    Geoff McDonald
    Geoff McDonald
    Kasiphon, The DNV reduction factors for single sided welds were added to SACS 10.0. Use 'ERD' in columns 78-80 on the FTOPT line to select this option. See the SACS 10.0 Connect Edition Release Notes for more information. Regards, Geoff
    • over 7 years ago
    • MAXSURF | MOSES | SACS | OpenWindPower
    • MAXSURF | MOSES | SACS | OpenWindPower Forum
  • RE: foundation superelements for various purposes

    Geoff McDonald
    Geoff McDonald
    The pair of forces are for the X and Y components of the pilehead stiffness as they are calculated independently. Refer to section 2.5.1 of the PSI manual. You want to linearize the piles using the loading that will be closest to the actual loading…
    • over 7 years ago
    • MAXSURF | MOSES | SACS | OpenWindPower
    • MAXSURF | MOSES | SACS | OpenWindPower Forum
  • RE: Fatigue analysis process

    Geoff McDonald
    Geoff McDonald
    1. You only need the scatter diagram data for the fatigue input file which is based upon the environment. There is no iterative process since the environment is not dependent upon your structure. 2. The fraction of design life is the ratio of the time…
    • over 7 years ago
    • MAXSURF | MOSES | SACS | OpenWindPower
    • MAXSURF | MOSES | SACS | OpenWindPower Forum
  • RE: A couple of questions

    Geoff McDonald
    Geoff McDonald
    In the case of tow fatigue, the naval architect would typically provide the structural engineer with response amplitude operators (RAO's) which are calculated using their hydrodynamic analysis in MOSES. The structural engineer would then calculate the…
    • over 7 years ago
    • MAXSURF | MOSES | SACS | OpenWindPower
    • MAXSURF | MOSES | SACS | OpenWindPower Forum
  • RE: Combining Fatigue Damages

    Geoff McDonald
    Geoff McDonald
    You can combine multiple fatigue analyses by generating fatigue damage files. On the first fatigue analysis, select the "output fatigue damage file" option in column 76 on the FTOPT2 line in the fatigue input (ftginp) file. A fatigue damage (ftgdmg…
    • over 7 years ago
    • MAXSURF | MOSES | SACS | OpenWindPower
    • MAXSURF | MOSES | SACS | OpenWindPower Forum
  • RE: User Defined SCF Values in SACS

    Geoff McDonald
    Geoff McDonald
    Kapildeb, I apologize for the confusion. It appears that the CONSCF card image was generated incorrectly for the manual and needs to be fixed. I have attached an older version of the same card image with the correct input for that table and I have submitted…
    • over 7 years ago
    • MAXSURF | MOSES | SACS | OpenWindPower
    • MAXSURF | MOSES | SACS | OpenWindPower Forum
  • RE: Spectral Fatigue Analysis

    Geoff McDonald
    Geoff McDonald
    Nalinii, The typical steps to perform a spectral fatigue analysis in SACS are as follows: Create pilehead superelement (optional) Extract mode shapes Transfer function generation Spectral fatigue It appears that you have already performed…
    • over 7 years ago
    • MAXSURF | MOSES | SACS | OpenWindPower
    • MAXSURF | MOSES | SACS | OpenWindPower Forum
  • Fatigue calculations

    Marwane Boutfirass
    Marwane Boutfirass
    Hello friends, I'm an internship in a Offshore Oil and Gas service and supply company and I started working with SACS recently. I have a question concerning fatigue analysis: What are the steps to follows to do a time history fatigue analysis knowing…
    • over 7 years ago
    • MAXSURF | MOSES | SACS | OpenWindPower
    • MAXSURF | MOSES | SACS | OpenWindPower Forum
  • SACS v5.3 fatigue analysis (warnings questions)

    fernando berra
    fernando berra
    Hi. I have been trying to make a fatigue analysis and I have some problems with the results of the analysis. First, when I make the dynamic analysis to extract modes and shapes, the result gives me a warning of no unity check option selected. what does…
    • over 9 years ago
    • MAXSURF | MOSES | SACS | OpenWindPower
    • MAXSURF | MOSES | SACS | OpenWindPower Forum
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