Dynamic simulation of beam-like structure with a crack subjected to a random moving mass oscillator

                                                        M. M. Ettefagh, M. H. Sadeghi and M. Rezaee

Vibration and Modal Analysis Laboratory, 51666-14766, Department of Mechanical Engineering, University of Tabriz, Tabriz, Iran

Abstract: In this paper, dynamic simulation of a beam-like structure with a transverse open crack subjected to a random
moving mass oscillator is investigated. The simultaneous effect of a crack and a random oscillator has not been addressed
up to now. The crack in the beam at different locations and with different depths is considered as one group of damage, each
as an individual imperfection. In addition, bearing immobility is considered as another type of problem in the beam. Mass,
stiffness, damping and velocity of the oscillator are assumed to be random parameters. An improved perturbation technique
is applied to reduce the simulation time. It was found that there is a maximum value of the variance of each uncertain
parameter, in which the maximum reliability of the perturbation method can be achieved, and that this maximum value can be
obtained by the Alpha-Hilber Monte-Carlo simulation method. The simulation results reveal that the mass and the velocity
uncertainty cause high uncertainty in the deflection of the beam. Also, the pattern of the deflection is not affected by different
random oscillator parameters, and as a result, the type of damage can be identified even with high uncertainty. Moreover,
the deflection in the nodes around the mid-span of the beam provides the best information regarding the imperfections, and
consequently leads to the best sensor locations in an actual experiment.

Keywords: bridge-vehicle interaction; moving mass oscillator; random parameters; Monte-Carlo simulation; perturbation

                      method



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