"Finite element modeling techniques for studying mechanical properties of nonlinear viscoelastic structural adhesives are presented here. Long term mechanical properties of the Ashland Urethane and Araldite Epoxy adhesive systems have been studied. The stress and strain based modified free volume theories developed at the University of Texas-Austin are verified by using them to model the nonlinear material properties of the aforementioned viscoelastic adhesives. The modified free volume theories work on the fundamental assumption that all viscoelastic material nonlinearities are dependent on free volume and that they can be captured entirely in a nonlinear shift factor definition. These shift factor definitions incorporate parameters to model the nonlinearities observed in shear dominated loading. Ashland Urethane and Araldite Epoxy were modeled using the stress and strain based approaches respectively. The modified free volume theories were incorporated into the NOVA-3D finite element analysis code, which was then used to simulate uniaxial tensile tests and biaxial Arcan tests. In an effort to analyze the effects of such adhesives on the overall mechanical properties of bonded structures, the effect of cohesive crack growth within a finite thickness adhesive layer was studied. Strain energy release rates for stationary cracks in double cantilever beam (DCB) specimens were modeled for the purpose of comparison with published data. Strain energy release rates for a DCB specimen made out of viscoelastic urethane and epoxy adhesives were computed for comparison with exact solution"--Abstract, page iii.
Dharani, Lokeswarappa R.
Mechanical and Aerospace Engineering
M.S. in Mechanical Engineering
University of Missouri--Rolla
viii, 80 pages
© 2000 Sreesh Kumar Inguva, All rights reserved.
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Inguva, Sreesh Kumar, "Finite element modeling of structural adhesives using nonlinear viscoelastic analysis" (2000). Masters Theses. 1928.
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