STRENGTH CONSIDERATIONS IN CONTROLLABLE PITCH PROPELLER DESIGN

Strength calculations for propellers are usually made using nominal static load values with fluctuations due to circumferential wake field variations superimposed. The allowable load is then determined by applying experimentally obtained material properties (Smith/Goodman diagrams) on the computed stress pattern. Approval of the final calculations by the Classification Societies is contingent upon the strengthening of certain components to ensure a higher survival rate in off-design conditions. Poor engineering judgement in applying these heavy duty requirements can lead to constructions where strength levels at several critical points is badly harmonized. This can lead to severe damage to the propeller, shafting, gearbox or even the hull. The paper presents an analysis of two such cases resulting from grounding incidents. The requirements of Lloyd's Register, Germanischer Lloyd and Det norske Veritas for ice strengthening are compared with those of the Finnish- Swedish rules for the extreme ice class and shown to differ considerably. The Finnish-Swedish rules show a substantial increase in thickness of the blades for the lower power range, whereas the Lloyd's register percentage method results in a superfluous blade thickness for the high powers. A simplified analysis of the effects of underwater explosions on propeller and shafting is given and the paper concludes with examples of the calculation of stresses in complex shaped and loaded parts using modern numerical methods.

  • Supplemental Notes:
    • Third Lips Propeller Symposium, Drunen, Holland.
  • Corporate Authors:

    Lips Propeller Works

    Drunen,   Netherlands 
  • Authors:
    • Beek, GHM
    • HEIDEMANS, J
  • Publication Date: 1976-5

Media Info

  • Features: References;
  • Pagination: 13 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00152578
  • Record Type: Publication
  • Source Agency: British Ship Research Association
  • Files: TRIS
  • Created Date: May 11 1977 12:00AM