CALCULATION OF NATURAL VERTICAL HULL-VIBRATIONS

When a hull is represented by a non-prismatic box-type Timoshenko beam-system for the calculation of hull vibrations at the design stage, bending stiffness and shear stiffness are among the information required for computer input. In a previous article the Author discussed the determination of shear stiffness for the calculation of the higher natural frequencies and modes of vertical hull-vibrations. In the present article, he investigates various methods of determining bending stiffness for the calcualtion of the natural vertical vibrations, and compares the results obtained for a number of general cargo ships with vibration measurements carried out in the ships. The calculations take the effect of the superstructure in to account, and an approximate method for this is described, The computer program VERSCHWI was used in the calculation of the natural frequencies and modes; the method employed is explained. The bending-stiffness reduction factors (for plating effects) gave better results for a closed idealised hull cross-section than for an open one, For the rough caluclation of vibration in the early design stage, when an accurate stiffness distribtuion is not usually available, the Author recommends the use of standard bending and shear stiffness distributions (for which only the midship-section stiffnesses need be known), and includes diagrams for this purpose based on a number of cargo ships of different types, Order from: BSRA as No. 47,279.

• Corporate Authors:

  Institut fuer Schiffbau

  Wismarsche Strasse 617
  25 Rostock,   Germany 
• Authors:
  • PALM, L
• Publication Date: 1977

Language

• German

Media Info

• Features: References;
• Pagination: 5 p.
• Serial:
  • Schiffbauforschung
  • Volume: 16
  • Issue Number: 1/2
  • Publisher: Institut fuer Schiffbau

Subject/Index Terms

• TRT Terms: Bending; Cargo ships; Computer programs; Hulls; Measurement; Natural frequency; Shear stress; Stiffness; Vibration; Vibration control
• Uncontrolled Terms: Natural frequencies
• Old TRIS Terms: Bending stiffness; Computer programs (Hull vibration); Hull vibration; Shear stiffness; Vibration measurement
• Subject Areas: Design; Marine Transportation;

Filing Info

• Accession Number: 00173032
• Record Type: Publication
• Source Agency: British Ship Research Association
• Report/Paper Numbers: No.3/4
• Files: TRIS
• Created Date: Apr 12 1978 12:00AM