Accession Number : AD0753900

Title :   Elastic Wave Propagation in a Porous Laminated Composite.

Descriptive Note : Report for Feb-Jul 72,

Corporate Author : AEROSPACE CORP EL SEGUNDO CALIF LAB OPERATIONS

Personal Author(s) : Sve,Charles

Report Date : 28 DEC 1972

Pagination or Media Count : 40

Abstract : An analysis is presented for linear elastic wave propagation normal to the laminations of a periodically laminated porous composite. The porosity is randomly distributed throughout one constituent and is composed of small spherical voids. This type of porosity is called randomly periodic and produces Rayleigh scattering where the wavelength of the incident wave is much larger than the void diameter. Porosity also reduces the wave speed in a constituent and thereby affects geometric dispersion. A DISSIPATIVE EQUATION OF MOTION IS DEVELOPED FOR POROUS MATERIAL THAT INCLUDES A POROSITY-DEPENDENT WAVE SPEED AND A SCATTERING TERM THAT PROVIDES SPATIAL ATTENUATION. This equation is then used for a constituent of a composite, and a dispersion relation and pulse solution are obtained to determine the significance of porosity in a laminated composite. It is concluded that Rayleigh scattering produces a small damping effect in far-field pulse shapes and small-void porosity can be adequately simulated with an effective wave speed. (Author-PL)

Descriptors :   (*COMPOSITE MATERIALS, MECHANICAL WAVES), LAMINATES, POROUS MATERIALS, RAYLEIGH SCATTERING, EQUATIONS OF MOTION

Subject Categories : Laminates and Composite Materials

Distribution Statement : APPROVED FOR PUBLIC RELEASE