Accession Number : ADA305294

Title :   Lamination Residual Stresses in Hybrid Composites. Part 1.

Descriptive Note : Final rept.,

Corporate Author : IIT RESEARCH INST CHICAGO IL

Personal Author(s) : Daniel, I. M. ; Liber, T.

PDF Url : ADA305294

Report Date : JUN 1976

Pagination or Media Count : 168

Abstract : An experimental investigation was conducted to study lamination residual stresses for various material and loading parameters. The effects of hybridization on residual stresses and residual properties after thermal cycling under load were determined in angle-ply graphite/Kevlar/epoxy and graphite/S-glass/epoxy laminates. Residual strains in the graphite plies are not appreciably affected by the type and number of hybridizing plies. Computed residual stresses at room temperature in the S-glass plies reach values up to seventy-five percent of the transverse strength of the material. Computed residual stresses in the graphite plies exceed the static strength by approximately ten percent. In the case of Kevlar plies, computed residual stresses far exceed the static strength indicating possible early failure of these plies. Static testing of the hybrids above indicates that failure is governed by the ultimate strain of the graphite plies. In thermally cycled hybrids, in general, residual moduli were somewhat lower and residual strengths were higher than initial values.

Descriptors :   *RESIDUAL STRESS, *EPOXY LAMINATES, *GRAPHITE EPOXY COMPOSITES, STRESS STRAIN RELATIONS, STRESS ANALYSIS, STATIC LOADS, DEFORMATION, TENSILE STRESS, STIFFNESS, MATRIX MATERIALS, ROOM TEMPERATURE, THERMAL EXPANSION, SHEAR STRESSES, FLEXURAL STRENGTH, TENSION, DYNAMIC LOADS, FAILURE(MECHANICS), COMPRESSIVE STRENGTH, THERMAL CYCLING TESTS, THERMAL STRESSES, STATIC TESTS, AXIAL LOADS, CYCLIC LOADS, TRANSVERSE, UNIDIRECTIONAL, SHEAR STRENGTH, SILICA GLASS, HYBRIDIZATION, STRESS RELAXATION, STRUCTURAL INTEGRITY.

Subject Categories : Laminates and Composite Materials
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE