Spectral Fatigue Analysis

Hello sir/madam,

I am Nalinii here and I am a final year student from UTP.I need to run spectral fatigue analysis for jacket platform.I would like to know the step to conduct spectral fatigue analysis in SACS.I would be really glad if sir or madam will be able to help me to show me  the procedure  especially after the eigenvalue analysis because I am having problem starting from that part.

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  • Nalinii,

    The typical steps to perform a spectral fatigue analysis in SACS are as follows:

    1. Create pilehead superelement (optional)
    2. Extract mode shapes
    3. Transfer function generation
    4. Spectral fatigue

    It appears that you have already performed step 2 so you should have your mass matrix (dynmas) and mode shape (dynmod) files. You then need to generate a transfer function which is used to convert the wave spectra into stress ranges for the fatigue analysis. This wave response analysis utilizes the dynmod and dynmas files to generate a SACS common solution file (saccsf) which contains the responses which define the transfer function. You can then run a spectral fatigue analysis on this saccsf file to generate your fatigue damage.

    I would recommend looking at Sample08 located in your SACS installation directory which contains a working example of what I just described. You may also want to refer to Section 4.3 of the fatigue manual for a more in depth discussion of spectral fatigue as well as Sample Problems 1 and 2 in Section 6.0 of the manual for other examples of this type of analysis.

    Regards,

    Geoff

  • Hi Geoff,

    Sorry to use this post to ask, i feel it is related. When I chose the General Wave Response or Deterministic/Transfer Function, there were no SACS common solution file generated as output. I would like to know if this is a software bug or do I need to modify any parameter in the input files so that I can get the (saccsf) file.

    Thanks a lot for your help

  • Quoc,

    Sometimes analysis options may be available only when certain input is in your input files. It is possible that you are missing some critical input in the wave response input file. Unfortunately, it is difficult to say without looking at your files. If you would like, you can submit a service request  and attach your files so that one of our technical support representatives can take a closer look at the problem.

    Regards,

    Geoff

  • Geoff,

    Thank you for your quick reply. I could not access to service request (access denied). I send you the snapshot of my input file as below, hope you can help. I used the (seainp) file with Force Transfer Function so there is no wave response input file, this can be chosen in <Edit Dynamic Wave Options>. Please advise the method (other than service request) that I can send the file to you for investigation.

Reply Children
  • Quoc,

    It is possible that the "Use Wave Response Input File" option is set to "No" in your Dynamic Wave Options. Make sure this option is set to "Yes". I would recommend trying to recreate the analysis from scratch to ensure that the runfile options are not causing a problem. Otherwise, I don't think I can make any other comments without looking at your analysis files directly.

    Unfortunately a service request is the only method by which you can securely send and receive files. You may need to login to Bentley.com before trying to access the service request page. Try logging into https://connect.bentley.com/ and clicking the New Service Request link at the bottom of the page.