Eventos Anais de eventos
MECSOL 2022
8th International Symposium on Solid Mechanics
PLASTICITY EFFECT ON FATIGUE LIFE OF AERONAUTICAL STRUCTURES CONSIDERING A VARIABLE AMPLITUDE LOADING
Submission Author:
Natan Reis , SP
Co-Authors:
Natan Reis, Mariano Arbelo, Carlos Eduardo Chaves
Presenter: Natan Reis
doi://10.26678/ABCM.MECSOL2022.MSL22-0009
Abstract
This work analyzes the effect of plasticity in the fatigue life of aeronautical structures that experience a variable loading scenario, by comparing a strain-based fatigue approach against a classical stress-based fatigue approach, which is lately modified to account for plastic deformation through a simple plasticity correction model. This work uses a representative loading scenario based on what airplanes experience throughout their operational life, by implementing the standardize TWIST loading sequence. Moreover, the MINITWIST was used to verify the impact of a reduced spectrum that intends to be more suitable for testing. The material analyzed was aluminum 2024-T351 alloy and the geometry considered was an open-hole plate with 5 different stress concentration factors (1.0, 2.0, 2.5, 3.0, 3.33). Rainflow cycle counting method is used to quantify the number of cycles per flight. A stress-life curve coupled to the SWT’s mean stress correction and the Palmgren-Miner cumulative damage rule is used to determine the total fatigue damage. In addition, plastic deformation effects are accounted by adjusting the maximum stresses of cycles who overcome the material yield strength, using Neuber’s rule and Ramberg-Osgood equations iteratively. Results show that, for the spectra considered, the consideration of plasticity effects have increased the fatigue life by approximately 23% for a stress concentration factor of 3,33. Besides that, the use of MINITWIST loading spectra presented similar results of the TWIST, indicating that small amplitude load cycles do not affect much in fatigue life.
Keywords
TWIST fatigue method, fatigue strain-based approach, variable amplitude loading
