SLAMMING IMPACT PRESSURE

The objective of the work is to explore and resolve apparent differences in slamming pressure measurements from drop tests and seakeeping model tests so that results from both kinds of experiments can be used as a design basis. Specific areas covered include the influence of hull curvature and elasticity on slamming pressure, the effect of impact velocity on pressure, and the effects of entrapped air on impact pressure. A theoretical result for absolute impact pressure which includes both effects of structure elasticity and a liquid-air mixture is obtained. On the basis of the theory both a 'weak' slam which is a linear function of velocity and a 'strong' slam which is a quadratic function of velocity are identified. Model data were presented in the form of ratios of absolute impact pressure to ambient pressure and correlated on the basis of a theoretical model structure impedance ratio and a non-dimensional impact velocity. It is concluded that impact pressure results from drop tests of models whose non-dimensional impact velocity corresponds to the full-scale appear to provide a satisfactory design basis when the structure impedance ratio is scaled. In addition, it is concluded that seakeeping model impact pressure data does not appear to be a reliable design basis due to the relatively low impact velocity ratios associated with such tests. (Author)

  • Corporate Authors:

    MPR Associates, Incorporated

    1140 Connecticut Avenue, NW
    Washington, DC  USA 
  • Authors:
    • Sellars, F H
  • Publication Date: 1971-6

Media Info

  • Pagination: 81 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00025595
  • Record Type: Publication
  • Source Agency: National Technical Information Service
  • Report/Paper Numbers: MPR-282
  • Contract Numbers: N00014-71-C-0045
  • Files: TRIS
  • Created Date: Feb 4 1972 12:00AM