Type of Document Dissertation Author Tiwari, Nachiketa Author's Email Address email@example.com URN etd-051199-082137 Title Secondary Buckling of Laminated Composite Plates Degree PhD Department Engineering Mechanics Advisory Committee
Advisor Name Title Hyer, Michael W. Committee Chair Johnson, Eric R. Committee Member Librescu, Liviu Committee Member Plaut, Raymond H. Committee Member Ragab, Saad A. Committee Member Keywords
- snap through
- secondary buckling
- boundary conditions
Date of Defense 1999-05-03 Availability mixed AbstractSECONDARY BUCKLING OF LAMINATED COMPOSITE PLATES
Michael W. Hyer, Chairman
The postbuckling load carrying capacity of composite plates offers
immense potential to their applications for loads exceeding their primary
buckling load. However, such an efficient and economical usage of these
plates can be reliable only if the nonlinear postbuckling behavior of
these plates, which includes a good understanding of secondary buckling,
is understood thoroughly. The present investigation is an attempt to
understand secondary buckling of almost square composite clamped-simply
supported plates, both unstiffened as well as stiffened, in some detail.
With the help of the finite element method, a large number of numerical
studies have been conducted to understand the secondary buckling
characteristics. The sensitivity of these characteristics to variations
in boundary conditions, lamination sequence, imperfections, and stiffener
geometry has been considered. It has been found that the occurrence of
secondary buckling in clamped-simply supported plates under uniform end
shortening critically depends on the intensity of restrictions imposed on
the inplane normal displacements along the unloaded simply supported
edges of the plate. These restrictions could be due to the actual
boundary conditions at these edges, or due to the presence of stiffeners
along these edges. It has also been found that the presence of
imperfections significantly delays the event of secondary buckling.
Finally, it has been found that changes in lamination sequence of the
plate alter its secondary buckling characteristics in ways that are, in
general, quantitative in nature. The numerical investigations were
followed by a limited number of experiments involving the testing of
unstiffened as well as stiffened composite plates with the intent of
augmenting the confidence in the numerical predictions made. Three
different lamination sequences were considered during the testing phase
of this investigation. It was found that the agreement between
experimental data and numerical predictions was quite good. The
occurrence of secondary buckling followed the predictions closely.
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