Accession Number : AD0657461

Title :   DISPERSION OF FREE HARMONIC WAVES IN FIBER-REINFORCED COMPOSITES.

Descriptive Note : Technical rept.,

Corporate Author : NORTHWESTERN UNIV EVANSTON ILL STRUCTURAL MECHANICS LAB

Personal Author(s) : Achenbach,Jan D. ; Herrmann,George

Report Date : JUN 1967

Pagination or Media Count : 26

Abstract : A set of displacement equations of motion is proposed that is suitable for the dynamic analysis of fiber-reinforced composites. In deriving the equations, representative elastic moduli are used for the binder, and the elastic and geometric properties of the fibers are combined into effective stiffnesses. With the aid of certain assumptions regarding the deformation of the fibers, and by employing a smoothing operation, approximate kinetic and strain energy densities for the fiber-reinforced composite are obtained. Application of Hamilton's principle yields the displacement equations of motion. The proposed set of equations is employed to study the propagation of plane harmonic waves propagating in the direction of the fibers and normal to the fiber direction. Plane transverse waves propagating in the direction of the fibers are dispersive, and dispersion curves are shown. By proper choice of the representative elastic moduli of the binder, the phase velocity at infinite wave length for transverse waves propagating in the direction of the fibers, and the constant phase velocities for longitudinal waves and waves propagating in the other directions, agree with the values predicted by the effective modulus theory. (Author)

Descriptors :   (*MECHANICAL WAVES, *COMPOSITE MATERIALS), DEFORMATION, KINETIC ENERGY, EQUATIONS OF MOTION, SCATTERING, ELASTIC PROPERTIES, THEORY, FIBERS, PROPAGATION, DYNAMICS, REINFORCING MATERIALS

Subject Categories : Laminates and Composite Materials
      Textiles
      Radiofrequency Wave Propagation

Distribution Statement : APPROVED FOR PUBLIC RELEASE