Plenary Lecture

Special and Unusual Aspects Regarding Real Scale Impact Testing Methods for Large Beams

Dr. Carmen Debeleac
Research Center for Mechanics of Machines and Technological Equipments
University "Dunarea de Jos" of Galati
Calea Calarasilor 29, 810017, Braila

Abstract: The study deal with some particular aspects connected to the impact testing methods on real scale intended for instrumental dynamic analysis of large beams. Large beams for viaducts, bridges and other special construction applications necessitate a strictly analysis of transient states when are subjected both to regular and to fortuitous dynamic charges. Experimental tests of these elements are developed both in special setup places for a singular element, and "in situ" for the serviceable montage. The most usual way to give it a try of these beams with impulsive loads for real scale experiments is to use a special truck that passed over the transversal obstacles with known characteristics and installed directly upon the rolling way. In this case the instrumental data have to be complete by theoretical study that validate and give it a final confirmation of the qualitative and quantitative results.
The impulsive charge result as a function of the singular obstacle shape, dimensions and material characteristics, and of the number, characteristics and geometrical configuration and distribution of tires. This real scale impact test configuration has the main advantage of a great similarity with the transient charges that will happen in the future exploitation, and the experimental results produce a most realistic characteristic of beams. But, it required a very fine tuning between the obstacles setup montage with the truck movement parameters and the tires characteristics, so that the impact shock has both the necessary energy, and the suiting spectral distribution.
The author develops an analytic method useful in virtual simulation of these complex phenomenon and try to dignify the next major aspects: denote leading parameters of the process, order in a systematic manner the whole parameters that have influences, more or less, in the tire obstacle road interactions, put into the evidence the transient behavior of the large beams subjected to an intensive and various impulsive charges with direct relevance in power spectral distribution, and try to establish the right number of traducers and their spatial distribution (based on the optimum ratio between the instrumental requirements and the results accuracy). Also, it was made a computational dynamics study based on the classical wave equation with the final scope of marking out the longitudinal and transversal propagation phenomenon and their interferences.
A few partial concluding remarks are: the special aspects regarding this study results from the great number of parameters and the complexity of their relationships, the unusual aspects was dignified by the comparison between the experimental data and the computational models, the complexity and the difficulties of tuning do not recommend this method for ordinary tests, but the realistic manner of action and the final results accuracy propose it for each case.

Brief Biography of the Speaker:
Carmen Debeleac (born in 1972) received the PhD degree in Mechanical Engineering from University "Dunarea de Jos" of Galati, Romania, in 2006. She obtained a Master degree in Mechanics - Dynamics of Construction Equipments, in 2002, at the same University, and a Senior Manager degree for Scientific Research Projects at "Politehnica" University - AMCSIT Center, Bucharest, Romania, in 2006. Since 1997 she is a senior research scientist at the Research Center for Mechanics of Machines and Technological Equipments, at Engineering Faculty in Braila, University "Dunarea de Jos" of Galati, Romania. She is author of numerous research articles in referee journals and international conferences, covering theory of mechanics, dynamics of construction equipments, vibrations, modelling and simulation of dynamic phenomenon, technologies for construction equipments, and is co-author of the book (with G. Axinti, N. Dragan) Analytic Mechanics with Applications. She has led and was involved in various research projects and has a plenary lecture at WSEAS Intl. Conf. Recent Advances in Automation & Information 2009. She is a member of International Association of Engineers, Romanian Society for Theoretical and Applied Mechanics, Romanian Society of Acoustics, Romanian Association for Construction Technologies, Equipments and Mechanization, and she is managing editor, associate editor and reviewer for national and international journals and conferences.




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