Description
TitleOn the interaction of thermal buckling and debonding of patched structures
Date Created2011
Other Date2011-05 (degree)
Extentxvi, 201 p. : ill.
DescriptionThe widespread use of patched assemblies in engineering structures creates the need for better fundamental understanding of the failure phenomena of such structures to ensure their safe and effective usage. A structure possessing two substructures, the
“patch” and “baseplate”, with mismatched coefficients of thermal expansion is studied under thermal loading for two extreme edge conditions. The composite structure is taken as initially flawed, such that partial separation exists at the edges of the patch between the
two substructures. Two relevant failure mechanisms are sling-shot buckling and edge debonding (separation). Sling-shot buckling, first observed for perfectly intact structures under thermal loads, occurs when the structure dynamically slings from one equilibrium configuration to another in an opposite sense of deflection at a critical load. It is desired
to be able to predict and characterize buckling of the structure, and its coupling with debonding. The geometrically nonlinear problem is formulated via a variational formulation, which allows the boundaries of the domains of the structure to vary in addition to the displacements. The vanishing of the first variation of the potential energy yields governing equilibrium equations, boundary/matching conditions, and transversality
conditions. The transversality condition yields a Griffith type delamination criterion. A closed-form solution is obtained after recasting the problem in a mixed formulation. A stability analysis is performed using the second variation of the potential energy functional. The partially debonded structure is seen to possess a “dual nature”, where it is structurally different depending on the deflection, due to the existence of the initial
flaw. It experiences sling-shot buckling, which, coupled with the structure’s duality leads to what we refer to as “Buckle Trapping.” It is suggested that, for certain critical
temperature fields, the structure oscillates dynamically between unstable equilibrium configurations. In addition, examination of the energy release rate against the bond size reveals a variety of possible behaviors, dependent on flaw size, temperature difference,
and bond strength. It is observed how and when separation leads to thermal buckling, and vice versa. Through this analysis, the onset, extent, and stability of debonding, as well as the relationship with buckling, are diagnosed and characterized.
NotePh.D.
NoteIncludes bibliographical references
NoteIncludes vita
Noteby Pamela Marie Carabetta
Genretheses, ETD doctoral
Languageeng
CollectionGraduate School - New Brunswick Electronic Theses and Dissertations
Organization NameRutgers, The State University of New Jersey
RightsThe author owns the copyright to this work.
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