Title page for ETD etd-12192005-135309


Type of Document Dissertation
Author Hassan, Noha Mohamed
Author's Email Address nhassan@vt.edu
URN etd-12192005-135309
Title Damage Development in Static and Dynamic Deformations of Fiber-Reinforced Composite Plates
Degree PhD
Department Engineering Science and Mechanics
Advisory Committee
Advisor Name Title
Batra, Romesh C. Committee Chair
Case, Scott W. Committee Member
Hyer, Michael W. Committee Member
Inman, Daniel J. Committee Member
Thangjitham, Surot Committee Member
Keywords
  • Continuum damage mechanics
  • Inelastic behavior
  • Composite
  • Blast loads
Date of Defense 2005-12-13
Availability unrestricted
Abstract
A three-dimensional finite element code to analyze coupled thermomechanical deformations of composites has been developed. It incorporates geometric nonlinearities, delamination between adjoining layers, and damage due to fiber breakage, fiber/matrix debonding, and matrix cracking. The three damage modes are modeled using the theory of internal variables and the delamination by postulating a failure envelope in terms of the transverse stresses; the damage degrades elastic moduli. The delamination of adjoining layers is simulated by the nodal release technique. Coupled nonlinear partial differential equations governing deformations of a composite, and the pertinent initial and boundary conditions are first reduced to coupled ordinary differential equations (ODEs) by the Galerkin method. These are integrated with respect to time with the Livermore solver for ODEs. After each time step, the damage in an element is computed, and material properties modified. The code has been used to analyze several static and transient problems; computed results have been found to compare well with the corresponding test results. The effect of various factors such as the fiber orientation, ply stacking sequence, and laminate thickness on composite's resistance to shock loads induced by underwater explosions has been delineated.
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