Accession Number : ADA113601

Title :   Residual Stresses in Adhesive Joints.

Descriptive Note : Final rept. 1 Jul 79-15 Aug 81,

Corporate Author : TEXAS A AND M UNIV COLLEGE STATION MECHANICS AND MATERIALS RESEARCH CENTER

Personal Author(s) : Weitsman,Y.

Report Date : OCT 1981

Pagination or Media Count : 235

Abstract : This final report contains several theoretical and experimental investigations related to the response of adhesives and adhesive joints due to mechanical and environmental effects. The theoretical investigations strive to highlight some of the features that are attributable to the time-dependent behavior of polymeric resins. These include a thermoviscoelastic analysis of residual stresses where it is shown that viscoelastic relaxation may reduce those stresses by about 20% and that the non-linear behavior tends to redistribute the stresses, reducing the magnitudes of stress concentrations as time progresses. An analysis of moisture effects indicates that under exposure to cyclic relative humidity the most severe states of stress may occur under partial drying rather than at the fully saturated case. Numerical schemes are provided to assist in computations of non-linear viscoelastic stresses and in determining moisture profiles under transient conditions. Experimental investigations are presented for the characterization of the time-dependent mechanical response of FM-73 unscrimmed adhesive at various levels of stress and temperature. The response is related by means of a non-linear viscoelastic constitutive relation. The results are restricted to a uni-directional case with limited damage growth. In addition, it was shown experimentally that the effects of cure shrinkage on residual stresses are negligible whenever such shrinkage is not constrained against dilatational strain. (Author)

Descriptors :   *Adhesive bonding, *Bonded joints, *Residual stress, *Numerical analysis, Mathematical models, Stress analysis, Mechanical properties, Thermal properties, Viscoelasticity, Time dependence, Relaxation, Transients, Moisture, Humidity, Stress strain relations, Computations

Subject Categories : Adhesives, Seals and Binders
      Numerical Mathematics
      Couplers, Fasteners, and Joints
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE