Title page for ETD etd-07282008-134336
|Type of Document
||Janajreh, Ibrahim Mustafa
||An efficient technique for structural reliability with applications
|Heller, Robert A.
|Mook, Dean T.
|Plaut, Raymond H.
|Singh, Mahendra P.
|Date of Defense
An efficient reliability technique has been developed based on Response Surface Methodology
(RSM) in conjunction with the First Order Second Moment (FOSM) reliability method. The
technique is applied when the limit state function cannot be obtained explicitly in terms of the design
variables, i.e., when the analysis is performed using numerical techniques such as finite elements.
The technique has proven to be efficient because it can handle problems with large numbers
of design variables and correlated as well as nonnormal random variables. When compared with
analytical results, the method has shown excellent agreement. The technique contains a sensitivity
analysis scheme which can be used to reduce the computation time resulting in nearly the same
accuracy. This technique allows the extension of most finite element codes to account for probabilistic
analysis, where statistical variations can be added to the design variables.
An explicit solution for rocket motors consisting of propellant and steel case under environmental
temperature variations is compared to the RSM technique. The method is then used for
the analysis of rocket motors subjected to mechanical loads for which the stress analysis is performed
using the finite element method. The technique is also applied to study the reliability of a
laminated composite plate with geometric nonlinearity subjected to static and time dependent
loadings. Different failure modes were considered as well as different meshes. Results have shown
that when the relative size of the element is introduced into the probabilistic model, the same reliability
value is obtained regardless of the number of elements in the mesh. This is good because
it allows the technique to be used for problems where the failure region is unknown.
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