Identification of the operating parameters for the mechanical systeIdentification system using EMD algorithm

J Jonak,A Machrowska,J Bęc,J Podgórski,M Belhaq

doi:10.1051/matecconf/20168305001

Abstract

The subject of paper was a research on mechanical system with pneumatic coupling, consisting of a compressor turbine (T I ) and of so-called free driving turbine (T II ). The purpose of the tests is to determine the applicability of Empirical Mode Decomposition (EMD) algorithm to identify operating parameters of the mechanical system, which is necessary to build a system for structure condition monitoring with use of vibroacoustic method. There has been assumed possibility of easy separation of working frequencies of these components on order to estimate amplitudes generated by them.

Highlights

Identification of the operating parameters for the mechanical systems is crucial for the construction and development of monitoring and diagnosis systems
As an interesting example of the difficulties associated with the identification of operating parameters, which occur during vibration analysis we can indicate fluctuating load conditions [1] or changes in rotational speed of mechanical system components [2]
According to Huang [8], function h1(t) is an Intrinsic Mode Functions (IMFs), when it satisfies two conditions: in the whole data set, the number of extremes and the number of zero crossings must be either equal or differ at most by one, at any point the mean value m1(t) of the envelope defined by the local maxima, and the envelope defined by the local minima is zero

Summary

Introduction

Identification of the operating parameters for the mechanical systems is crucial for the construction and development of monitoring and diagnosis systems. Each of the elements of the monitored object is characterized by a number of frequency bands. Knowledge of these bands determines the correctness of the technical condition assessment. Input signal obtained as a result of measurements may constitute a nonlinear and non-stationary data set, resulting in significant limitations in case of application of commonly known analytical methods. As an interesting example of the difficulties associated with the identification of operating parameters, which occur during vibration analysis (performed by conventional techniques) we can indicate fluctuating load conditions [1] or changes in rotational speed of mechanical system components [2]. The object of research was the mechanical system, whose essential components were two turbines (TI and TII turbine) coupled pneumatically

EMD algorithm

Signal preprocessing

Results of EMD algorithm

EMD limitations

Conclusions