Type of Document	Dissertation
Author	Humfeld, G.Robert Jr.
URN	etd-05416181972480
Title	Mechanical Behavior of Adhesive joints Subjected To Thermal Cycling
Degree	Master of Science
Department	Engineering Science and Mechanics
Advisory Committee	Advisor Name Title D. A. Dillard Committee Chair T. C. Ward none V. Giurgiutiu none
Keywords	thermal cycling adhesive bond polymer residual thermal stress viscoelasticity fracture mechanics thermal ratchetting
Date of Defense	1997-02-07
Availability	unrestricted
Abstract The effect of thermal cycling on the state of stress in polymeric materials bonded to stiff elastic substrates was investigated using numerical techniques, including finite element methods. The work explored the relationship between a cyclic temperature environment, temperature-dependent viscoelastic behavior of polymers, and thermal stresses induced in a constrained system. Due to the complexity of developing a closed-form solution for a system with time, temperature, material properties, and boundary conditions all coupled, numerical techniques were used to acquire approximate solutions. Descriptions of attempted experimental verification are also included. The results of the numerical work indicate that residual stresses in an elastic-viscoelastic bimaterial system incrementally shift over time when subjected to thermal cycling. Tensile axial and peel stresses develop over a long period of time as a result of viscoelastic response to thermal stresses induced in the polymeric layer. The applied strain energy release rate at the crack tip of layered specimens is shown to similarly increase. The rate of change of the stress state is dependent upon the thermal cycling profile and the adhesive¹s thermo-mechanical response. Discussion of the results focuses on the probability that the incrementing tensile residual stresses induced in an adhesive bond subjected by thermal cycling may lead to damage and debonding, thus reducing durability.
Files	Filename       Size       Approximate Download Time (Hours:Minutes:Seconds)     28.8 Modem   56K Modem   ISDN (64 Kb)   ISDN (128 Kb)   Higher-speed Access    etd.pdf 565.40 Kb 00:02:37 00:01:20 00:01:10 00:00:35 00:00:03   ETD.pdf 565.40 Kb 00:02:37 00:01:20 00:01:10 00:00:35 00:00:03

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