25 documents found, page 1 of 3
Experimental analysis of the plastic CTOD to characterize the variable amplitud...
Gómez Gonzales, Giancarlo Luis; Vasco-Olmo, Jose Manuel; Antunes, Fernando; Neto, Diogo M.; Díaz, Francisco A.In this paper, the plastic component of the crack-tip opening displacement (CTODp) is experimentally evaluated to characterize the fatigue crack growth behavior in a Grade 2 titanium sample under single overload with constant amplitude loading conditions. The CTOD measurements were performed with the 2D-Digital Image Correlation (DIC) technique. The experimental results show a linear correlation between CTODp a...
Experimental determination of the reversed plastic zone size around fatigue cra...
Gómez Gonzales, Giancarlo L.; Ortiz González, Julián A.; Antunes, Fernando; Neto, Diogo M.; Díaz, Francisco A.This paper provides an experimental methodology to determine the reversed plastic zone size at the crack tip under cyclic loading through high-resolution DIC measurements. Due to the small size of this region, a 3D-DIC system based on two cameras in a stereoscopic setup with an optical microscope was used in the experimental setup. Fatigue crack growth tests were performed on AISI 1020 steel specimens to evalua...
Fatigue crack growth modeling considering a hybrid propagation strategy
Sérgio, Edmundo R.; Antunes, Fernando; Neto, Diogo M.Fatigue results from the occurrence of several damage mechanisms and their interactions. The cyclic plastic strain and damage accumulation at the crack tip are widely pointed as the main agents behind fatigue crack growth (FCG). In this work, the authors propose the prediction of FCG through a node release numerical model that offers several possibilities regarding the modeling of the mechanisms behind fatigue....
Fatigue Crack Propagation under Christmas Tree Load Pattern
Neto, Diogo M.; Sérgio, Edmundo R.; Jesus, Francisco; Newman, James C.; Antunes, FernandoMost mechanical components are subject to dynamic loads, which can cause failure in service. This study aims to evaluate the effect of variable amplitude loadings on fatigue crack growth (FCG) in CT specimens produced with the AA2024-T351 aluminum alloy. Specifically, it is intended to predict the FCG rate when the specimen is subjected to a complex loading pattern, named the “Christmas Tree Spectrum”. Crack gr...
A Novel Specimen Produced by Additive Manufacturing for Pure Plane Strain Fatig...
Jesus, Joel de; Borges, Micael; Antunes, Fernando; Ferreira, José; Reis, Luis; Capela, CarlosFatigue crack growth is usually studied using C(T) or M(T) specimens with throughthickness cracks. The objective of the present study is to propose a cylindrical specimen with central crack, produced by additive manufacturing. This geometry allows to have pure plane strain state along the whole crack front, avoiding the complexities associated with corner points, crack shape, and variation of crack closure alon...
Fatigue Performance of Thin Laser Butt Welds in HSLA Steel
Riofrío, Patricio G.; Antunes, Fernando; Ferreira, José; Batista, António Castanhola; Capela, CarlosThis work is focused on understanding the significant factors affecting the fatigue strength of laser-welded butt joints in thin high-strength low-alloy (HSLA) steel. The effects of the weld profile, imperfections, hardness, and residual stresses were considered to explain the results found in the S-N curves of four welded series. The results showed acceptable fatigue strength although the welded series present...
Numerical simulation of fatigue crack growth based on accumulated plastic strain
Borges, M. F. M.; Neto, D. M.; Antunes, FernandoFatigue crack growth (FCG) is simulated here by node release, which is made when the accumulated plastic strain reaches a critical value. The numerical procedure is very robust, showing a very fast stabilization and independence relatively to the load considered for node release. A critical accumulated plastic strain of 110% was obtained for the 2024-T351 aluminium alloy, comparing the experimental value of da/...
Fatigue Crack Growth from Notches: A Numerical Analysis
Borges, Micael Frias; Caldas, Manuel; Antunes, Fernando; Branco, Ricardo Nuno Madeira Soares; Prates, Pedro André DiasA numerical approach based on plastic crack tip opening displacement (CTOD) was followed to study fatigue crack growth (FCG) from notches. The identification of fundamental mechanisms was made considering notched and unnotched models, with and without contact of crack flanks. Di erent parameters were studied, namely, notch radius, crack length, stress state, and material. The notch increases the plastic CTOD, a...
A noção de ideia e o problema da representação na ética de Espinosa
Antunes, FernandoOrientador: Prof. Dr. Paulo Vieira Neto; Dissertaçao (mestrado) - Universidade Federal do Paraná, Setor de Ciencias Humanas, Letras e Artes, Programa de Pós-Graduaçao em Filosofia. Defesa: Curitiba, 24/09/2010; Inclui referências; Área de concentraçao: História da filosofia moderna e contemporânea; Resumo A noção de ideia pode assumir basicamente três sentidos distintos na Ética de Espinosa. No primeiro a compr...
Fatigue Crack Growth in Maraging Steel Obtained by Selective Laser Melting
Antunes, Fernando; Santos, Luís; Capela, Carlos; Ferreira, José A. M.; Costa, José; Jesus, Joel de; Prates, PedroSelective Laser Melting (SLM) is an additive manufacturing technology, ideal for the production of complex-shaped components. Design against fatigue is fundamental in the presence of cyclic loads, particularly for these materials which typically have significant porosity, high surface roughness and residual stresses. The main objective here is to study fatigue crack growth (FCG) in the 18Ni300 steel obtained by...