Accession Number : ADA336551

Title :   Viscoelastic Response of Prestressed Composite Cylinders for Rotating Machinery Applications

Descriptive Note : Final rept. Oct 95-Dec 96

Corporate Author : ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD

Personal Author(s) : Tzeng, Jerome T.

PDF Url : ADA336551

Report Date : JAN 1998

Pagination or Media Count : 43

Abstract : Energy storage devices such as composite rotors are built with radial pre-compression to enhance mechanical performance; however, the pre-load might decrease due to the viscoelastic behavior of materials at elevated temperatures. In this investigation, an analytical solution is developed to study the viscoelastic problem of thick-walled cylinders. The analysis accounts for ply-by-ply variations of properties, fiber orientations, and temperature gradients through the thickness of cylinders. Fiber reinforced composite materials generally illustrate extreme anisotropy in viscoelastic behavior. The viscoelasticity exists mainly in matrix-dominant properties such as transverse and shear while the fiber-dominant properties behave more like elastic mediums. Accordingly, the viscoelastic characteristics of composite cylinders are quite different from those of isotropic cylinders. Currently, finite element packages such as ABAQUS, ANSYS, and DYNA3D are not suitable for the viscoelastic analysis of composite cylinders because of the lack of anisotropic viscoelastic elements. The pre-stress in the hoop-wound fibers, which generates radial compression in the cylinders, might decrease due to Poisson's effect alone from the creep behavior in the transverse properties of composite. The result also shows the effects of lay-up construction and fiber orientations on the anisotropic behavior of composite cylinders.

Descriptors :   *VISCOELASTICITY, *FIBER REINFORCED COMPOSITES, MECHANICAL PROPERTIES, TEMPERATURE GRADIENTS, CYLINDRICAL BODIES, ANISOTROPY, SHEAR STRESSES, CREEP, ENERGY STORAGE, POISSON EQUATION, PRESTRESSING, FLYWHEELS.

Subject Categories : Laminates and Composite Materials
      Machinery and Tools

Distribution Statement : APPROVED FOR PUBLIC RELEASE