National Repository of Grey Literature 2 records found  Search took 0.01 seconds. 
Modelling approaches to the stress wave propagation in a cracked specimen
Kruisová, Alena ; Kopačka, Ján ; Kober, Jan
One of the essential tasks of non-destructive testing is to detect a crack in a specimen. It is well known that a component with a crack exposed to a harmonic excitation of a given frequency\nhas a nonlinear response as a function of the excitation amplitude. The focus of this paper is the numerical modelling of this phenomenon using the finite element method with the consideration\nof the contact constraint at the crack interface. In addition to the nonlinear transient dynamic problem solved by explicit time integration, a more efficient procedure based on the harmonic\nbalance method is developed. The results of numerical simulations are also compared with experimentally obtained data.
Efficient numerical computation of the steady-state response and stability analysis of the rotor systems with squeeze film dampers
Molčan, M. ; Ferfecki, P. ; Zapoměl, Jaroslav
The aim of this paper is to demonstrate capabilities of the created numerical procedure, which is based on harmonic balance method. Furthermore, the procedure incorporates the alternating frequency-time domain technique and the arc-length parameterization to solve the steady-state response of nonlinear systems in efficient manner, including unstable branches. The stability of the motion was assessed by two methods: the 2n-pass method and Hill’s method. The procedure was verified on an example from literature to prove its sufficient accuracy and subsequently, the procedure was applied on the finite element model of the rotor systém mounted on the squeeze film dampers. The carried out computational simulations confirmed that the created procedure is efficient for the strongly nonlinear response and it gives similar results as the time integration.

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