Accession Number : ADA326167

Title :   Load Transfer Characteristics and Residual Stresses in Composite Material Systems.

Descriptive Note : Final rept. 1 Dec 92-30 Sep 96,

Corporate Author : UTAH UNIV SALT LAKE CITY DEPT OF MATHEMATICS

Personal Author(s) : Folias, E. S.

PDF Url : ADA326167

Report Date : FEB 1997

Pagination or Media Count : 67

Abstract : In this study, the load transfer characteristics of a broken fiber are investigated. The problem consists of a cylindrical fiber that is embedded into a matrix material. The fiber axis is assumed to coincide with the z-axis and a crack is assumed to be present on the plane z =0 and for r < a. Far away from the crack, the fiber is subjected to uniform external load of sigma sub 0. Moreover, adjacent to the crack and along the interface, the matrix and fiber surfaces are assumed to slide along the interface length -c < z < c, where there is a nonuniform friction. On the other hand, perfect bonding is assumed to prevail all along the remarking interface. Residual stresses due to curing and thermal stresses due to differences between the thermal expansion coefficients of the matrix and fiber may have a major effect on the microstresses within a composite material system and must be added to the stresses induced by the external mechanical loads. Such microstresses are often sufficient to produce microcracking even in the absence of external mechanical loads, example during the cooling process. In this report a few selected results are presented for a material system consisting of SIC-6 cylindrical fibers which are periodically embedded into a plate matrix consisting of beta21 material. The results are based on a linear elastic-micromechanics model which provides the stress profiles due to (1) a uniform load perpendicular to the direction of the fibers and (2) due to a thermal expansion mismatch.

Descriptors :   *FIBER REINFORCED COMPOSITES, *MATRIX MATERIALS, *RESIDUAL STRESS, *MICROCRACKING, INTERFACES, LOADS(FORCES), ELASTIC PROPERTIES, SURFACES, THERMAL EXPANSION, TEMPERATURE COEFFICIENTS, MICROMECHANICS, FRICTION, THERMAL STRESSES.

Subject Categories : Laminates and Composite Materials
      Mechanics
      Thermodynamics

Distribution Statement : APPROVED FOR PUBLIC RELEASE