to Determine Natural Oscillation Frequencies of a Cylindrical Shell, Fastened by Vari-Distant Rigidity Ribs

摘要

The problem of free oscillations of a cylindrical shell, reinforced by stringers, which have various geometric and elastic qualities and situated along the shell, at arbitrary distance from each other, is considered as a contact problem, by the theory of shells and rods of open profile. Solving equations of shell oscillations, is sought in form of derivative of three functions. Introduced are two methods of comparing a frequency equation of a stringer reinforced shell. Frequency equation was obtained in form of a determinant of 8-th magnitude and in form of determinant of k-magnitude, where k is the number of stringers. In first form, the frequency equation is suitable for numerical calculations, and in second one - for qualitative analysis of frequency spectrum of shell, fastened by stringers. Thoroughly investigated, was the frequency spectrum of a shell, fastened by one stringer. It was established that it bears a discrete nature and that in it may be contained eight frequencies of a nonreinforced shell. It was shown, how elastic and geometric characteristics of the stringer, as well as its disposition, on the shell, affect the magnitude of eight frequencies of a reinforced shell. (Author)