19 documents found, page 1 of 2
Interpolating CTS specimens' mode I and II stress intensity factors using artif...
Miguel Gomes Simões Baptista, Ricardo; Infante, Virgínia; Borrego, L. F. P.; Sérgio, Edmundo R.; Neto, Diogo M.; Antunes, F. V.Fracture mechanics parameters, such as the stress intensity factor (SIF), are fundamental for the analysis of fracture, fatigue crack growth and crack paths. SIFs of a cracked body can be determined either experimentally or numerically. Analytical solutions of SIF are very useful, but their determination from discrete values can be extremely complex when there are many independent variables. In this paper, arti...
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...
Considering the stiffness of the forming tools in the numerical analysis of the...
Oliveira, Marta C.; Neto, Diogo M.; Alves, J. L.; Menezes, Luís F.Ironing can occur in cylindrical cup drawing whenever the thickness of the drawn flange is larger than the gap between the punch and the die. This is particularly relevant for materials that present r-values lower than 1.0, such as the aluminium alloys, since they tend to present more thickening of the flange. The aim of this study is to evaluate numerically the impact of the elastic deformation of the forming ...
Effect of L‐T and S‐T orientations on fatigue crack growth in an aluminum 7050‐...
Borges, Micael F.; Antunes, Fernando V.; Jesus, Joel; Branco, Ricardo; Prates, Pedro; Neto, Diogo M.This study is focused on the anisotropic fatigue crack growth (FCG) behavior of an aluminum AA7050-T7451 plate. L-T and S-T orientations were studied in M(T) samples with W = 50 mm, in mode I loading, with R-ratio of +0.05. A numerical approach was used, assuming that crack tip plastic strain is the crack driving force. A purely kinematic elastic–plastic model was calibrated using experimental data from low cyc...
Effect of Residual Stresses on Fatigue Crack Growth: A Numerical Study Based on...
Neto, Diogo M.; Borges, Micael F.; Sérgio, Edmundo R.; Antunes, Fernando V.Residual stresses affect the fatigue behavior, given that compressive stresses delay the phenomenon, while tensile stresses accelerate it. However, the mechanisms behind the effect of residual stresses are not totally understood. A numerical study is developed here to understand the effect of thermal residual stresses (TRSs) on fatigue crack growth (FCG). The crack driving force was assumed to be the cumulative...
Analysis of ESAFORM 2021 cup drawing benchmark of an Al alloy, critical factors...
Habraken, Anne Marie; Aksen, Toros Arda; Alves, J. L.; Amaral, Rui L.; Betaieb, Ehssen; Chandola, Nitin; Corallo, Luca; Cruz, Daniel J.This article details the ESAFORM Benchmark 2021. The deep drawing cup of a 1 mm thick, AA 6016-T4 sheet with a strong cube texture was simulated by 11 teams relying on phenomenological or crystal plasticity approaches, using commercial or self-developed Finite Element (FE) codes, with solid, continuum or classical shell elements and different contact models. The material characterization (tensile tests, biaxial...
On the effect of the tension-compression ratio on forming of isotropic materials
Oliveira, Marta C.; Prcela, Ivan; Cvitanić, Vedrana; Neto, Diogo M.; Alves, J. L.; Menezes, Luís F.It is generally believed that the choice of the yield criterion used to describe the plastic behaviour of isotropic metallic materials does not affect much the accuracy of the predictions of forming operations. For this reason, the von Mises yield criterion is widely used for modelling their plastic behaviour. However, according to the von Mises yield criterion, the ratio between the yield stresses in tension a...