Title page for ETD etd-07102002-135308


Type of Document Dissertation
Author Goyal, Vijay Kumar
Author's Email Address vgoyal@vt.edu
URN etd-07102002-135308
Title Dynamic Stability of Uncertain Laminated Beams Subjected to Subtangential Loads
Degree PhD
Department Aerospace and Ocean Engineering
Advisory Committee
Advisor Name Title
Kapania, Rakesh K. Committee Chair
Johnson, Eric R. Committee Member
Plaut, Raymond H. Committee Member
Singh, Mahendra P. Committee Member
Thangjitham, Surot Committee Member
Keywords
  • Dynamic Stability
  • Nonconservative Loading
  • Finite Element
  • Probabilistic Mechanics
  • Uncertainties
  • Laminated Beams
Date of Defense 2002-07-02
Availability unrestricted
Abstract
Because of the inherent complexity of fiber-reinforced laminated composites, it can be challenging to manufacture composite structures according to their exact design specifications, resulting in unwanted material and geometric uncertainties. Thus the understanding of the effect of uncertainties in laminated structures on their static and dynamic responses is highly important for a reliable design of such structures. In this research, we focus on the deterministic and probabilistic stability analysis of laminated structures subject to subtangential loading, a combination of conservative and nonconservative tangential loads, using the dynamic criterion.

Thus a shear-deformable laminated beam element, including warping effects, is derived to study the deterministic and probabilistic response of laminated beams. This twenty-one degrees of freedom element can be used for solving both static and dynamic problems. In the first-order shear deformable model used here we have employed a more accurate method to obtain the transverse shear correction factor. The dynamic version of the principle of virtual work for laminated composites is expressed in its nondimensional form and the element tangent stiffness and mass matrices are obtained using analytical integration. The stability is studied by giving the structure a small disturbance about an equilibrium configuration, and observing if the resulting response remains small.

In order to study the dynamic behavior by including uncertainties into the problem, three models were developed: Exact Monte Carlo Simulation, Sensitivity-Based Monte Carlo Simulation, and Probabilistic FEA. These methods were integrated into the developed finite element analysis. Also, perturbation and sensitivity analysis have been used to study nonconservative problems, as well as to study the stability analysis using the dynamic criterion.

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