Banca de DEFESA: Felipe Maganha de Lima

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : Felipe Maganha de Lima
DATE: 21/12/2023
TIME: 14:15
LOCAL: Microsoft TEAMS
TITLE:

STOCHASTIC MODELING AND FATIGUE PREDICTION APPROACHES FOR OVERHEAD CONDUCTOR UNDER RANDOM LOADING CONDITIONS

KEY WORDS:

Overhead Conductor; Aeolian vibrations; Stochastic modeling; Fatigue life prediction

PAGES: 186
BIG AREA: Engenharias
AREA: Engenharia Mecânica
SUMMARY:

Overhead conductor are subjected to natural loads due to wind action, which can result in severe levels of mechanical vibrations known as aeolian vibration. The wind speed induces cyclic loads with variable and random amplitude behaviors. Depending on the degree of material damage generated by the mechanical component over time, these loads can impact the fatigue life of the conductor cable by contributing to the fatigue failure process of internal and external wires.
To comprehend and mitigate the effects of wind-induced fatigue, in addition to considering the variability of wind speed that defines the prevailing wind patterns in the region, it is crucial to take into account the conductor characteristics such as stiffness, constructive geometry, self-damping response, and the failure mechanism’s behavior (quantity and distribution of broken wires). In this way, the study consisted of an analysis set responsible for identifying, in the time and frequency domains, the optimal fatigue life prediction model for validation with experimentally observed fatigue life. It also involved the stochastic modeling of the failure process, aiming to identify and keep track of parameters associated with the failure mechanism of this type of mechanical component (peak-to-peak displacement, stress amplitude, percentage damage contribution, and others).
Vibratory tests were conducted with stationary and ergodic excitation conditions in a weak sense to evaluate the statistical and spectral characteristics of the dynamic response of the conductors, specifically the vibratory response at 89 mm from the last point of contact between the conductor and the clamp. Samples of CAA 397.5 MCM IBIS and CAL/AAAC 838 MCM cables were subjected to an Everyday Stress (EDS) of 20\%, and tested under various acceleration classes. The intention is to assess the conductor's vibratory responses associated with these types of excitations characterized by narrow-band behaviors, because the severe levels of vibration amplitude can be considered a potential intensifier of the material damage process, reducing the fatigue life of the component. After the tests and data analysis, the obtained results were statistically evaluated to identify the level of stationarity present in the sample functions. Additionally, a comparison was made between the developed methodologies for fatigue life prediction in the time domain and in the frequency domain.
In summary, wind-induced fatigue in transmission line conductor cables is a significant phenomenon that demands attention in design and maintenance programs. Understanding fatigue mechanisms, appropriate stochastic modeling, and consideration of environmental loading effects are essential to ensure the safety, reliability, and longevity of these critical energy infrastructures.

COMMITTEE MEMBERS:
Externo à Instituição - ANDRÉ LUIS PINTO - IFB
Interno - 1523261 - COSME ROBERTO MOREIRA DA SILVA
Presidente - 1249764 - JORGE LUIZ DE ALMEIDA FERREIRA
Externo ao Programa - 1509037 - LUIS AUGUSTO CONTE MENDES VELOSO - null