Accession Number : AD0702108

Title :   FURTHER INVESTIGATIONS INTO THE MICRODYNAMICS OF WAVE PROPAGATION.

Descriptive Note : Annual summary rept. Jun 68-Jun 69,

Corporate Author : WHITTAKER CORP SAN DIEGO CALIF RESEARCH AND DEVELOPMENT/SAN DIEGO

Personal Author(s) : Haener,Juan ; Puppo,Alberto

Report Date : AUG 1969

Pagination or Media Count : 40

Abstract : This continuing analytical program is concerned with establishing equations to define wave propagation in unidirectional, multi-fiber reinforced composites. It was found that the exact solution and the approximate solution yield the same numerical results for displacements, stresses, and propagation velocities for a model of rotational symmetry. It was also found that only the fundamental propagative mode in a composite materials can propagate waves. The higher modes have cut-off frequencies below shich propagation is impossible. They are strongly attenuated just below the cut-off frequency, and immediately above it dispersion is very high. The more commonly used fiber composites materials, glass epoxy, may be used for an example. Those with a fiber content of 60% have a cut-off frequency of 10 times 10 to the sixth power cycles/second for the first higher mode; those with a fiber content of 80% have a cut-off frequency of 26 times 10 to the sixth power cycles/second. It is therefore justifiable to use solutions in which the dynamics of the system are simplified or solutions which are approximated in such a way that they deal mainly with the fundamental mode. (Author, modified-PL)

Descriptors :   (*REINFORCED PLASTICS, MECHANICAL WAVES), GLASS TEXTILES, EPOXY RESINS, LOADS(FORCES), PROPAGATION, STRESSES, APPROXIMATION(MATHEMATICS), PARTIAL DIFFERENTIAL EQUATIONS

Subject Categories : Laminates and Composite Materials
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE