Accession Number:

ADA243077

Title:

A Frequency-Domain Method for Estimating the Incidence and Severity of Sliding

Descriptive Note:

Final rept. 1 Jan-30 Aug 1991

Corporate Author:

DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP HYDROMECHANICS DEPT

Report Date:

1991-08-30

Pagination or Media Count:

46.0

Abstract:

A frequency-domain method of predicting the incidence of personnel or equipment sliding is presented which includes the linearized forces due to roll, pitch, longitudinal, lateral and vertical accelerations, and also the effects of non-zero mean heel. The predictions of the method are compared with the results of observations of at-sea sliding incidents, and good correspondence is obtained. A simple approximation for the duration of threshold exceedance probability density is described, and used to develop a method for predicting the incidence of slides greater than a certain severity. The method applies for arbitrary lateral and vertical acceleration, but only to the case in which the longitudinal acceleration is negligible. An example of the application of the method is presented. It is argued that ship motions such as roll, pitch, lateral and longitudinal accelerations are the wrong physical parameters for expressing seakeeping criteria. These criteria become simpler when expressed in terms of the incidence of degrading events such as helicopters sliding, and are equally applicable to all vessel types.

Subject Categories:

  • Numerical Mathematics
  • Marine Engineering

Distribution Statement:

APPROVED FOR PUBLIC RELEASE