• How to get the linear damping coefficient considered in time domain?

    Mahesh Talagana
    Mahesh Talagana
    I wanted to compare the damping coefficients considered in time domain against the coefficients calculated using BV NR 493 rules (attached). Can anyone tell me how to get the linear damping coefficients used in time domain? Otherwise, can we input the…
    • over 1 year ago
    • MAXSURF | MOSES | SACS | OpenWindPower
    • MAXSURF | MOSES | SACS | OpenWindPower Forum
  • Damping of SPAR floating structure using heave plate

    Gilrandi Adi Negoro
    Gilrandi Adi Negoro
    Hi all, I really need some help with my undergraduate thesis. So, I've been analyzing the effects of heave plate in the keel of SPAR to motion response of the SPAR structure using MOSES, and experimental trials. so here is my question. As far as I know…
    • over 4 years ago
    • MAXSURF | MOSES | SACS | OpenWindPower
    • MAXSURF | MOSES | SACS | OpenWindPower Forum
  • PDF

    A BRIEF NOTE ON INERTIA & DAMPING COEFFICIENTS in MOSES

    Bit-na Seo
    Bit-na Seo
    This document explains how the added inertia coefficients and linearized damping coefficients are calculated and reported in MOSES. Often asked questions are also discussed at the end of the document.
    • DampingNotes_v.1.pdf
    • View
    • Hide
    • over 4 years ago
    • MAXSURF | MOSES | SACS | OpenWindPower
    • MAXSURF I MOSES I SACS I OpenWindPower Files
  • MOSES Add Linear Damping Force to a System

    Bit-na Seo
    Bit-na Seo
    This document and a set of sample files are intended to describe how to add linear damping force to a system using #DRAG command.
    • #drag.zip
    • over 5 years ago
    • MAXSURF | MOSES | SACS | OpenWindPower
    • MAXSURF I MOSES I SACS I OpenWindPower Files
  • Basis for the suggested added mass and damping for launch barges

    Jason Forcier
    Jason Forcier
    Q: What is the basis for the suggested added mass and damping for launch barges? REV 7.04 A: Originally these numbers were based on the high frequency results in a frequency domain analysis for nominal launch barge in a nominal launch position. These…
    • over 7 years ago
    • MAXSURF | MOSES | SACS | OpenWindPower
    • MAXSURF | MOSES | SACS | OpenWindPower - Wiki
  • Remove all viscous damping terms

    Jason Forcier
    Jason Forcier
    Q: How can I remove all viscous damping terms in the damping matrix when computing RAOs? REV 5.03 A: Do not include any Morrison elements, #PLATE or #AREA commands. Also, the Tanaka damping must be turned off using the A_TANAKA BNAME NONE command, and…
    • over 7 years ago
    • MAXSURF | MOSES | SACS | OpenWindPower
    • MAXSURF | MOSES | SACS | OpenWindPower - Wiki
  • Alter damping values for really large structures

    Jason Forcier
    Jason Forcier
    Q: Should I alter the default damping values for really large structures, such as big TLPs? REV 5.10 A: You should turn off the Tanaka damping and use -cs_curr 1 1 1 on PGEN or &describe piece. This adds some viscous damping to the problem, which is…
    • over 7 years ago
    • MAXSURF | MOSES | SACS | OpenWindPower
    • MAXSURF | MOSES | SACS | OpenWindPower - Wiki
  • Add a damping of some percentage of critical

    Jason Forcier
    Jason Forcier
    Q: How can I add a damping of some percentage of critical? REV 6.01 A: A problem here is the definition of critical damping. Critical damping is defined in terms of the natural period, but there is no "natural period". There is another FAQ on natural…
    • over 7 years ago
    • MAXSURF | MOSES | SACS | OpenWindPower
    • MAXSURF | MOSES | SACS | OpenWindPower - Wiki
  • Low frequency damping

    Jason Forcier
    Jason Forcier
    Q: How does MOSES get low frequency damping? REV 7.00 A: SRESPONSE does not include low frequency damping. The only damping here is due to viscous effect, so you can claim that this is conservative. In time domain, there is ample damping from all the…
    • over 7 years ago
    • MAXSURF | MOSES | SACS | OpenWindPower
    • MAXSURF | MOSES | SACS | OpenWindPower - Wiki
  • Input a 6x6 damping matrix

    Jason Forcier
    Jason Forcier
    Q: How can I input a 6x6 damping matrix? REV 7.00 A: In MOSES you model physical things. Thus, there is no need to input a 6x6 matrix. Consider for example, a single dashpot. This can be modeled as either damping added to a GSPR connector or one term…
    • over 7 years ago
    • MAXSURF | MOSES | SACS | OpenWindPower
    • MAXSURF | MOSES | SACS | OpenWindPower - Wiki
  • Model of the BALDER have #TUBEs added for viscous damping

    Jason Forcier
    Jason Forcier
    Q: Why does the model of the BALDER have #TUBEs added for viscous damping when your answer to a FAQ says to use -CS_CURR 1 1 1? REV 7.04 A: The #TUBEs are included in the model so that we can show the effects of using them. See Section XIII of the verification…
    • over 7 years ago
    • MAXSURF | MOSES | SACS | OpenWindPower
    • MAXSURF | MOSES | SACS | OpenWindPower - Wiki
  • Types of damping

    Jason Forcier
    Jason Forcier
    Q: What is the difference between damping, drag, drag caused by current, and drag caused by waves? REV 7.04 A: First let's us agree that drag and damping are considered the same. Now, divide damping into radiation damping and viscous damping. The first…
    • over 7 years ago
    • MAXSURF | MOSES | SACS | OpenWindPower
    • MAXSURF | MOSES | SACS | OpenWindPower - Wiki
  • Damping

    Daniel Veen
    Daniel Veen
    This section contains frequently asked questions on the subject of damping and/or drag.
    • over 4 years ago
    • MAXSURF | MOSES | SACS | OpenWindPower
    • MAXSURF | MOSES | SACS | OpenWindPower - Wiki
  • "*** WARNING: Negative On Diagonal Of Damping

    Jason Forcier
    Jason Forcier
    Q: What does the message "*** WARNING: Negative On Diagonal Of Damping" mean? REV 5.10 A: It means you have negative values in either your damping values and/or your added mass values resulting from the hydrodynamic pressure computation. We discovered…
    • over 7 years ago
    • MAXSURF | MOSES | SACS | OpenWindPower
    • MAXSURF | MOSES | SACS | OpenWindPower - Wiki
  • Linear radiation damping and viscous damping coefficients

    Jason Forcier
    Jason Forcier
    Q: Do the damping matrices obtained using the v_matrices command include both linear radiation damping and viscous damping coefficients? REV 7.01 A: No, what you get with MATRICES in FREQ_RESP contains both, what you get with V_MATRICES in HYDRODYNAMICS…
    • over 7 years ago
    • MAXSURF | MOSES | SACS | OpenWindPower
    • MAXSURF | MOSES | SACS | OpenWindPower - Wiki
  • Viscous damping linearization

    Jason Forcier
    Jason Forcier
    Q: Is the viscous damping linearized stochastically or harmonically? REV 7.02 A: By default, MOSES linearizes harmonically via a "equivalent linearization". If you tell it to, MOSES will perform a spectral linearization. Remember that the viscous forces…
    • over 7 years ago
    • MAXSURF | MOSES | SACS | OpenWindPower
    • MAXSURF | MOSES | SACS | OpenWindPower - Wiki
  • Damping in a cable

    Jason Forcier
    Jason Forcier
    Q: How can I include damping in a cable? REV 7.04 A: Use the -DAMPING option on the class definition command.
    • over 7 years ago
    • MAXSURF | MOSES | SACS | OpenWindPower
    • MAXSURF | MOSES | SACS | OpenWindPower - Wiki