Banca de DEFESA: Thiago Arnaud Abreu de Oliveira

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : Thiago Arnaud Abreu de Oliveira
DATE: 24/11/2023
TIME: 09:00
LOCAL: TEAMS
TITLE:

AUTOMATION OF PARIS PARAMETERS IN AIRCRAFT FUSELAGE PANEL DESIGNS

KEY WORDS:

Multiscale analysis; Fatigue life; Aircraft fuselage; Boundary element method; Optimal Function

PAGES: 146
BIG AREA: Engenharias
AREA: Engenharia Civil
SUBÁREA: Estruturas
SPECIALTY: Mecânica das Estruturas
SUMMARY:

The problem addressed in this work focuses on resolving the need to establish a secure relationship between the C and m parameters of the Paris Law and the number of fatigue life cycles in aircraft fuselage designs. This relationship is particularly important for designers who are constantly seeking rapid and reliable simulation methods that produce secure average data, thereby avoiding damage processes and, consequently, the occurrence of accidents.
To achieve this, this work has developed a new damage tolerance philosophy based on critical compliance, as an alternative to the classical method that considers the critical crack size. In this new methodology, it is assumed that the structure, even when damaged, is capable of withstanding the actions for which it was designed until the detection of local instability when compliance reaches the critical value. Thus, the overall objective is to obtain the optimal function of the Paris parameters that withstands the required number of cycles.
To accomplish this objective, the methodology employed here hinges on a multiscale approach comprising two key stages. In the initial stage, the macro model is utilized to analyze internal stresses and pinpoint the critical point's location. In the subsequent stage, the micro model is implemented to assess the number of cycles leading to local instability. As a result, the optimal N(C, m) curve (representing the number of cycles as a function of C and m) is derived, ensuring structural integrity.
To validate this methodology, three case studies were conducted utilizing BEMCRACKER2D and BEMLAB2D programs. These studies entailed the analysis of internal stress fields for each model, followed by simulations of crack propagation, ultimately yielding critical compliance and estimates fatigue life. Consequently, the m(C) function, which correlates the Paris parameters with the required number of cycles in each model, was established.
In conclusion, the developed technique facilitates generalization to various other models. By providing data on the Paris parameters C and m, this approach presents an innovative means to correlate these parameters with the required number of cycles in the design. Furthermore, the methodology based on critical compliance offers a fresh perspective for evaluating damage tolerance, signifying a substantial advancement in the safety and reliability of structures subject to fatigue.

COMMITTEE MEMBERS:
Presidente - 1439182 - GILBERTO GOMES
Externo ao Programa - 404714 - JOSE MANOEL MORALES SANCHEZ - UnBExterno à Instituição - Davidson de Oliveira França Júnior
Externo à Instituição - Iago Freitas de Almeida
Externo à Instituição - LUIZ CARLOS WROBEL - PUC - RJ