Accession Number : AD0638206

Title :   MECHANICAL IMPEDANCE AND MOBILITY CONCEPTS.

Corporate Author : NAVAL RESEARCH LAB WASHINGTON D C

Personal Author(s) : O'HARA,G. J.

Report Date : 29 JUL 1966

Pagination or Media Count : 14

Abstract : The purpose of the report is to discuss fundamental concepts involved in mechanical impedance and mobility. The equations used in the formulation of the concepts are examined as to meaning and content. It is demonstrated for any prescribed structure that every possible observed mobility element is independent of the number and location of the other measurement points and that every possible observed mechanical impedance element is not. The effects upon the mobility and impedance arrays are examined for simple expansions and contractions of the tensor. Since mobility is not affected by changes in the number of observation points, remeasurement is not required at the observation points that are retained during expansion or contraction of the tensor; but since any changes in the observation points for impedance measurements requires changes in the blocking forces, the observation points that are retained are affected. An undamped lumped parameter system (a three-mass system on a rigid base and constrained to unidirectional motion) serves to illustrate the effects on the tensor elements of impedance or of mobility of the choice of the number and location of measurement points. (Author)

Descriptors :   (*MECHANICAL PROPERTIES, *TENSOR ANALYSIS), (*MOBILITY, STRUCTURES), ELASTIC PROPERTIES, MEASUREMENT, FORCE(MECHANICS), VIBRATION

Subject Categories : Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE