Determination of the Vibration Diagnostic Parameters Indicating the Presence of a Mode I Crack in a Blade Airfoil at the Main, Super- and Subharmonic Resonances

Finite Element Model for Analysis of Characteristics of Shrouded Rotor Blade Vibrations

“…Its detailed consideration and analysis allow one to draw the following conclusions: 1. The character of the AFC is almost identical during in-phase excitation using both nonlinear and linearized calculation models [5]. 2.…”

“…For the purposes of simulating the shrouding of the blades, the procedure described earlier [5,13,15] was proposed, whose main thesis are as follows:…”

“…Thus, the modeling of contact interaction between the shrouds (it is generally of nonlinear nature) requires its linearization. The values of contact pressure and its distribution over the planes of contact between the shrouds required to perform the numerical experiments are taken from [5,10,15]. Based on these calculation results, the natural frequencies of vibrations of the blade assembly under investigation were determined for the selected variants of the contact interaction between the shrouds.…”

“…The calculations on the determination of the influence of contact interaction modeling of the shrouds were made employing the assembly consisting of two blades, which is the simplest regular system as shown in [5,15]. Here it is possible to fully investigate the influence of different factors on the vibrations of the studied structures.…”

“…Rotor blades with flange shrouding are the most critical and, at the same time, most heavily-loaded structural elements of gasturbine engines. Finite element modeling (FEM) of rotor blades should consider the features of the airfoil geometry, contact interaction between the shrouds of adjacent blades, as well as their possible local damages in the engine operation [3,5,7].…”