Accession Number : ADA306404

Title :   Viscoelastic Behavior of a Nonlinear, Fiber-Reinforced Plastic. Part 2.

Descriptive Note : Final rept. 1 Jan-31 Dec 68,

Corporate Author : PURDUE RESEARCH FOUNDATION LAFAYETTE IN

Personal Author(s) : Lou, Y. C. ; Schapery, R. A.

PDF Url : ADA306404

Report Date : APR 1969

Pagination or Media Count : 63

Abstract : The nonlinear mechanical properties of a unidirectional, glass fiber-epoxy composite at 164 F are characterized by using creep and recovery tests together with a constitutive equation based on a thermodynamic theory. Our experimental effort covers studies on specimens with fiber orientations at theta = 0 deg, 30 deg, 45 deg, 60 deg and 90 deg with respect to the uniaxial loading 0 direction. The results for theta = 0 deg specimen show that the composite is linearly elastic for the load range studied, but nonlinear viscoelastic behavior is observed for the other orientations. Guided by the nonlinear constitutive equation, the creep and recovery data are plotted on double-logarithmic paper, and the material properties are found by shifting the data to form a master curve' for each fiber orientation. Prediction of master curves of theta = 45 deg and 60 deg from master curves of theta = 0 deg, 90 deg and 30 deg is made. Four principal creep compliances are estimated by using the master curves and tensor transformation relations. Finally, we use the nonlinear equation to predict strain response due to multiple-step loading and unloading.

Descriptors :   *FIBER REINFORCED COMPOSITES, *ORIENTATION(DIRECTION), *REINFORCED PLASTICS, MECHANICAL PROPERTIES, THERMODYNAMICS, VISCOELASTICITY, ELASTIC PROPERTIES, STRAIN(MECHANICS), SHEAR STRESSES, GLASS FIBERS, CREEP, EPOXY COMPOSITES, AXIAL LOADS.

Subject Categories : Laminates and Composite Materials

Distribution Statement : APPROVED FOR PUBLIC RELEASE