Accession Number : AD0670482

Title :   THE EFFECT OF A SECOND MODE AND NEARBY STRUCTURES ON SHOCK DESIGN VALUES.

Descriptive Note : Interim rept.,

Corporate Author : NAVAL RESEARCH LAB WASHINGTON D C

Personal Author(s) : O'Hara,G. J. ; Petak,L. P.

Report Date : 05 APR 1968

Pagination or Media Count : 29

Abstract : A dynamic design-analysis method developed at NRL for shipboard equipment requires the use of design-shock spectrum values, which provide appropriate input data. These design values are derived from measured data of a number of realistic shock tests. Theoretical and experimental investigations of the past provided insight which has resulted in a set of design data for use with the design-analysis method; these are the presently specified inputs, and studies continue to improve them. The investigation reported here attempts to show the effects upon design-shock spectrum values of a second mode and a nearby structure. This is done by comparing the design-shock spectrum value of a simple, single-degree-of-freedom structure with the design spectrum values obtained for a two-mode structure and with the design value obtained when another simple structure is placed adjacent to the original one. The results indicate that for a wide range of weight and frequency parameters the design spectrum value obtained using a simple model is not greatly sensitive to the effects of multimodes and adjacent structures and, thus, sufficiently defines the appropriate input value. However, for certain ranges of the weight and frequency parameters, gross differences can occur between the design values for the simple system and those of the more complex systems. (Author)

Descriptors :   (*STRUCTURES, *SHOCK RESISTANCE), (*SHIP STRUCTURAL COMPONENTS, SHOCK RESISTANCE), SENSITIVITY, INTERACTIONS, STRESSES, SHOCK(MECHANICS), UNDERWATER EXPLOSIONS, EQUATIONS OF MOTION, MATHEMATICAL MODELS

Subject Categories : Marine Engineering
      Structural Engineering and Building Technology
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE