Search academic texts

Information × Registration Number 0209U002512, 0106U002864 , R & D reports Title The research of dynamic characteristics of cylindrical elements of constructions with fillers by experimental and numerical methods popup.stage_title Head Boodak Valerij Dmitrovich, Registration Date 16-02-2009 Organization Nykolayiv state pedagogical university popup.description2 The work is dedicated to the defining of the main dynamic features of thin shell, and to the study of influence effects of liquid to the amplitude-frequency features of self-vibrations in cantilever-supported shells. The important and timely problem here is a detail and maximally precise account of factors, which influence the character of self-vibrations in shells that are filled with liquid partially and fully. Highly accurate effective approach on basis of holographic interferometery method is proposed for the solving of this problem. There is received the regular spectrum of the first sixteen frequencies and vibration forms in filled shells, at research of which it is set, that the interferential picture of vibration forms is stable, the deformation of interferential band is absent. It is found that for the prospected empty shells the regularity of bendings character of shell surface of proper vibrations forms is preserved. It is experimentally confirmed that minimum fundamental frequency changes with the change of length of shell and proper by it form of vibrations as well. For the prospected shells, the calculation of minimum fundamental frequency according by the method of progressive approximations with the help of Electronic calculable machine and frequency parameter on the known formulas is conducted. Comparison of results of calculation with the experimental finding, made by author, allows drawing a conclusion about their satisfactory coincidence. A regular spectrum of the first sixteen frequencies and vibration forms in cantilever-supported shells for the different levels of liquid filling is got. Considerable influence of liquid level on the vibration forms and complex character of bendings at the shell surface in lengthwise direction is exposed. It is set the unmonotony of changes of vibrodisplacement of shell surface in antinode of vibrations. It is defined that the value of self-vibrations frequencies changes unmonitonically according to the liquid filling level. The value of the frequencyis on the horizontal plateau or decreases. The maximal diminishing of frequencies is found out under conditions of the fully filled shell for the vibration forms with the bellow amount of circulated half waves. It is set that the displacement of nodal line among the vibrations antinodes and the value of coordinate of maximal bending of shell surface in lengthwise direction influences the character frequency change. it is confirmed experimentally, that with the increasing of liquid filling level the vibration form, which is proper to minimum frequency, can change. in this case the amount of half-waves increases circle-wise. A calculation of the self-vibrations frequencies in fully filled shells is conducted according to the known formulas. The limits of satisfactory concordance of the calculated data with the results of the experiment are conducted. The approach realized in the work has wide possibilities for the study of dynamic features of shells of different forms and structures under boundary conditions.It can be used for making conclusions about approximations of the built theoretical modes and about the accuracy of the figure-analytic methods of solving corresponding groups of tasks. Key-words: a thin cylindrical shell, liquid, inner vibrations, holographic interferometery. Product Description popup.authors popup.nrat_date 2020-04-02 Close