Title page for ETD etd-32498-145636


Type of Document Dissertation
Author Hause, Terry J.
Author's Email Address anon2247@vt.edu
URN etd-32498-145636
Title Thermomechanical Postbuckling of Geometrically Imperfect Anisotropic Flat and Doubly Curved Sandwich Panels
Degree PhD
Department Engineering science and Mechanics
Advisory Committee
Advisor Name Title
Librescu, Liviu Committee Chair
Hajj, Muhammad R. Committee Member
Henneke, Edmund G. II Committee Member
Kapania, Rabesh K. Committee Member
Librescu, Liviu Committee Member
Thangjitham, Surot Committee Member
Keywords
  • Sandwich Structures
  • Buckling and Postbuckling
  • Geometrically Nonlinearities
  • Snap-Through
  • Geometric Imperfections
Date of Defense 1998-04-17
Availability unrestricted
Abstract
Sandwich structures constitute basic components of advanced supersonic/hypersonic flight and launch vehicles. These advanced flight vehicles operate in hostile environments consisting of high temperature, moisture, and pressure fields. As a result, these structures are exposed to large lateral pressures, large compressive edge loads, and high temperature gradients which can create large stresses and strains within the structure and can produce the instability of the structure. This creates the need for a better understanding of the behavior of these structures under these complex loading conditions. Moreover, a better understanding of the load carrying capacity of sandwich structures constitutes an essential step towards a more rational design and exploitation of these constructions.

In order to address these issues, a comprehensive geometrically non-linear theory of doubly curved sandwich structures constructed of anisotropic laminated face sheets with an orthotropic core under various loadings for simply supported edge conditions is developed. The effects of the radii of curvature, initial geometric imperfections, pressure, uniaxial compressive edge loads, biaxial edge loading consisting of compressive/tensile edge loads, and thermal loads will be analyzed. The effect of the structural tailoring of the facesheets upon the load carrying capacity of the structure under these various loading conditions are analyzed. In addition, the movability/immovability of the unloaded edges and the end-shortening are examined.

To pursue this study, two different formulations of the theory are developed. One of these formulations is referred to as the mixed formulation, While the second formulation is referred to as the displacement formulation. Several results are presented encompassing buckling, postbuckling, and stress/strain analysis in conjunction with the application of the structural tailoring technique. The great effects of this technique are explored. Moreover, comparisons with the available theoretical and experimental results are presented and good agreements are reported.

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