Type of Document	Dissertation
Author	Engelstad, Stephen Philip
URN	etd-08252008-162620
Title	Nonlinear probabilistic finite element modeling of composite shells
Degree	PhD
Department	Engineering Mechanics
Advisory Committee	Advisor Name Title Reddy, Junuthula N. Committee Chair Cramer, Mark S. Committee Member Frederick, Daniel Committee Member Johnson, Eric R. Committee Member Singh, Mahendra P. Committee Member
Keywords	Composite materials
Date of Defense	1990-11-05
Availability	restricted
Abstract A probabilistic finite element analysis procedure for laminated composite shells has been developed. A total Lagrangian finite element formulation, employing a degenerated 3-D laminated composite shell element with the full Green-Lagrange strains and first-order shear deformable kinematics, forms the modeling foundation. The first-order second-moment technique for probabilistic finite element analysis of random fields is employed and results are presented in the form of mean and variance of the structural response. The effects of material nonlinearity are included through the use of a rate-independent anisotropic plasticity formulation with the macroscopic point of view. Both ply-level and micromechanics-level random variables can be selected, the latter by means of the Aboudi micromechanics model. A number of sample problems are solved to verify the accuracy of the procedures developed and to quantify the variability of certain material type/structure combinations. Experimental data is compared in many cases, and the Monte Carlo simulation method is used to check the probabilistic results. In general, the procedure is quite effective in modeling the mean and variance response of the linear and nonlinear behavior of laminated composite shells.
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