Nonlinear vibroacoustical free oscillation method for crack detection and evaluation
Leonid M. Gelman, Sergey V. Gorpinich · The Journal of the Acoustical Society of America · 1998
For detection and evaluation of cracks, the vibroacoustical method of free oscillations, based on nonlinear dynamics of a tested object, is widely used. However, in spite of wide practical application, the theoretical basis of this method is insufficiently investigated. The theoretical research of the decrement of the damped nonlinear free oscillations is given in the presence of a crack in a tested object. New generalizations of the decrement for nonlinear oscillations are proposed and investigated. New analytical expressions between the decrement and relative size of a crack, factors of damping, and the natural frequency of a tested object without a crack are received, on the basis of which a new testing feature is proposed and investigated. The cases of small and large damping are considered. The results obtained allow one to explain the phenomena that appeared at the method usage. [Work supported in part by the John D. and Catherine T. MacArthur Foundation.]