On the dynamic analysis of engineering structures with high and low level random uncertainties

Cheepsomsong, Thana (2014) On the dynamic analysis of engineering structures with high and low level random uncertainties. Doctoral thesis (PhD), University of Sussex.

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Abstract

The ability to predict the effect of dimension and thickness variability on the dynamic
response of realistically uncertain engineering structures is examined in this thesis.
Initially, available methods for predicting key response statistics and probabilities, for
both low and high frequencies are examined to establish their strengths and limitations
for specified levels of random dimension variability. For low frequency applications,
the ability of Direct Integration (DI) and the First-Order Reliability Method (FORM) to
predict exceedance probability is examined. For high frequency applications, the ability
of the methods of Statistical Energy Analysis (SEA) and DI to predict the mean and
standard deviation of the energy response is examined.

The use of Extreme Value (EV) theory is included as a way to bound responses using
simulated or measured responses. The strengths and limitations of Monte Carlo
simulation methods are explored for both low and high frequency responses of
randomly uncertain structures using both simple mode superposition plate-structure
solutions and (commercially available) finite element solutions for coupled plate
structures.

To address, without the need to undertake expensive Monte Carlo simulation, the
problem of predicting response bounds for structures with varying levels of uncertainty,
a novel DI-EV method is developed and examined. It is tested first on a simple plate
structure, then on a coupled plate structure, with low-level and high-level random
dimension and thickness uncertainty. In addition, the method is compared with the
SEA-EV method.

The thesis shows that the results from the existing SEA-EV bounding approach gives
good bounds only at particular frequencies and mainly for low levels of dimension
variability. In contrast, the proposed DI-EV bounding approach compare extremely well
with Monte Carlo simulations, which is not only at all frequencies but also with both
low-level and high-level uncertainties, for simple and coupled plate structures with
dimension and thickness variation.

Item Type: Thesis (Doctoral)
Schools and Departments: School of Engineering and Informatics > Engineering and Design
Subjects: T Technology > TA Engineering (General). Civil engineering (General) > TA0630 Structural engineering (General)
Depositing User: Library Cataloguing
Date Deposited: 29 Oct 2014 06:52
Last Modified: 25 Sep 2015 13:49
URI: http://sro.sussex.ac.uk/id/eprint/50745

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