Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
ANALYSIS OF THE FATIGUE LIFE PREDICTION OF OVERHEAD CONDUCTORS CONSIDERING THE TIME AND FREQUENCY DOMAIN
Submission Author:
Emanuely Ugulino Cardoso , DF
Co-Authors:
Emanuely Ugulino Cardoso, JORGE FERREIRA
Presenter: Emanuely Ugulino Cardoso
doi://10.26678/ABCM.COBEM2021.COB2021-0472
Abstract
Overhead conductors are the most requested components in a transmission line, due to the vibratory movement resulting from the action of the wind. In Brazil the highest incidence is associated with aeolian vibration, being the main cause of conductor fatigue failure. Fatigue can be defined as a progressive failure of a component under repetitive, cyclic or oscillating loads and the fatigue damage over time is irreversible and cumulative. One of the main methodologies for life estimation is based on the fatigue curve of the S-N (stress-life) material. In many cases, stresses have random characteristics, and the estimate of fatigue damage depends on the loading history. Thus, the life estimate can be performed in the time domain, from the cycle count in each stress level of the recorded signal, based on rainflow cycle counting, or in the frequency domain based on power spectral density moments of the structure. Considering the results of fatigue tests carried out with the CAA 397.5 MCM - IBIS conductor which are available in the literature, this research aims to reconstruct the stress histories at critical points of the conductor and estimate his life. From the estimates made with the reconstructed signals it will be possible to compare them with the results obtained from the tests and verify the efficiency of the methodology employed. The analyses consider the effect of discretization of the power spectrum and the technique of simulation of stochastic processes in the fatigue life predictions, so that predictions will be made through spectral and time models. From the results it was noticed that when making estimates in the time domain, fatigue life values are more variable than in the frequency domain, because the statistics and spectral measures are less influenced by the signal size, thus, the most accurate models were Rayleigh and Dirlik.
Keywords
conductors fatigue, aeolian vibration, Power Spectrum, rainflow
