Fuzzy analysis of a friction-induced vibration system: frequency and time aspects
Résumé
In fuzzy sets theory, the reference method, used to propagate uncertainty, relies on the Zadeh’s Extension Principle. For finite element mechanical applications, a direct implementation, practically based on a full design of experiments, entails a large computational time and is not conceivable in design step. So, a complete strategy is here proposed to calculatefuzzy frequencies and fuzzy coalescence graph for a friction-induced vibration problem. Firstly, to reduce the number ofdeterministic simulations, a functional dependence analysis for frequencies is performed and an optimization problem is thendefined for specific values of friction coefficient to determine the extreme variation of behaviors. Secondly, to reduce the computational cost of each deterministic evaluation, several methods are proposed to reanalyse with precision the frictional contact problem and modified frequencies. A specific focus is here proposed concerning the use on a high order discrete-time system to control the mechanical contact conditions. A numerical application is proposed to show the efficiency of the proposed strategy and to highlight the effects of the input variations on instabilities