An analysis of the suppression of the heaving motion of surface platforms of spherical, 1/4 ellipsoidal, and 1/8 ellipsoidal hull form by means of dynamic tuning is presented. The system is comprised of a flat, circular damper disk suspended from a surface platform by means of an elastic wire rope. The analysis attempts to determine the proper combination of damper-wire rope characteristics for maximum motion attenuation for each platform shape over the entire range of expected wave frequencies. The system is mathematically modeled as two coupled, non-linear, ordinary differential equations. The system is assumed to possess two vertical degrees of freedom with the surface platform subject to sinusoidal excitation determined by the Haskind relations. Provisions are made in the analysis for the possibility of the wire rope connection going slack. The problem is solved for twenty foot long platforms by a form of the Runge-Kutta numerical technique. Results indicate the spherical form to be superior in degree of motion suppression by means of the dynamic tuning. A preliminary design of the damper-wire rope characteristics of these perameters for arbitrary sized spheres is also illustrated.

  • Supplemental Notes:
    • Resulted from a joint program at Department of Ocean Engineering, MIT, and Woods Hole Oceanographic Institution.
  • Corporate Authors:

    Massachusetts Institute of Technology

    Department of Ocean Engineering, 77 Massachusetts Avenue
    Cambridge, MA  United States  02139
  • Authors:
    • Simonetti, P J
  • Publication Date: 1973-6

Subject/Index Terms

Filing Info

  • Accession Number: 00048349
  • Record Type: Publication
  • Source Agency: Massachusetts Institute of Technology
  • Report/Paper Numbers: MS Thesis
  • Files: TRIS
  • Created Date: Oct 31 1973 12:00AM