40 documents found, page 1 of 4
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...
Propagation of notch fatigue cracks on maraging steel under biaxial conditions
Cruces, A.S.; Exposito, A.; Branco, R.; Borrego, L. P.; Antunes, F. V.; Lopez-Crespo, P.The current work aims at characterizing the fatigue behaviour of an additively manufactured maraging steel. This is a class of highstrength steels widely used in aircracft, aerospace, offshore and military industries thanks to its good performance in terms of strength, toughness, ductility, dimensional stability and weldability. Fabrication of such steel via laser-beam powder bed fusion (additive manufacturing)...
Effect of variable amplitude block loading on fatigue crack growth
Neto, D. M.; Borges, M. F.; Silva, J. M.; Antunes, F. V.The objective is to study the effect of load blocks on fatigue crack propagation. To carry out this study, the finite element program DD3IMP will be used, with the fatigue crack propagation being controlled by the value of the plastic deformation at the end of the crack. The material used was the Ti6Al4V alloy obtained by the selective laser fusion manufacturing process. Regarding the studied load patterns, two...
Influence of specimen orientation on fatigue crack growth in 7050-T7451 and 205...
Jesus, J. S.; Antunes, F. V.; Prates, P.; Branco, R.; Antunes, P. V.; Borrego, L. P.; Neto, D. M.The effect of L-T and S-T orientations on FCGR is here in studied in 7050-T7451 and 2050-T8 aluminum alloys. The Low-cycle fatigue tests and hardness measurements have shown that specimen orientation has a minor effect on material plastic hardening. Lower FCG rates are obtained for both materials in the L-T orientation, which can be associated to the resistance at grain boundaries. The larger cyclic plastic zon...
Multiaxial fatigue behaviour of maraging steel produced by selective laser melting
Branco, R.; Costa, J. D.; Capela, C.; Antunes, F. V.; Macek, W.; Ferreira, J. A. MartinsThis paper studies the multiaxial fatigue behaviour of maraging steel samples produced by selective laser melting. Hollow cylindrical specimens with transverse circular holes are subjected to different in-phase bending-torsion loading scenarios. Fatigue crack initiation sites and fatigue crack angles are predicted from the first principal stress field. Fatigue lifetime is computed using a straightforward approa...
Effect of remaining ligament on fatigue crack growth
Jesus, Joel; Neto, D. M.; Fernandes, R. F.; Borges, M. F.; Antunes, F. V.; Sérgio, E. R.Fatigue crack growth (FCG) has been studied assuming that Keff is the crack driving force. However, the effect of crack ligament on FCG rate is not clear. Experimental-numerical work was developed in the 18Ni300 maraging steel considering different load blocks with the same initial K. No effect of crack ligament was observed experimentally, which was explained by the inexistence of crack closure effects. In t...
Single overloads FCG modeling considering damage accumulation
Sérgio, E. R.; Borges, M. F. M.; Neto, D. M.; Antunes, F. V.; Pais, J. P.In this study, Fatigue Crack Growth (FCG) in a CT specimen, submitted to single overloads, is predicted by a node release numerical model, which considers the plastic strain to be the main FCG driving force. The Gauss-Tvergaard-Needleman (GTN) damage model was implemented to account for the, inevitable, growth and nucleation of microvoids in the occurrence of high levels of plastic strain. Crack closure shown t...
Simulation of crack growth in T-welded joints - residual stress field effect
Ramalho, A. L.; Antunes, F. V.; Ferreira, J. A. M.In this article, a three-dimensional finite element model is used to predict the growth of cracks at the weld toe of a T-joint. The model is developed using the MSC Marc software. Fatigue life is estimated by integrating the Paris-Erdogan law and the stress intensity factors are obtained by the virtual crack closure technique. The influence of residual stresses generated by plastic deformation at the weld toe o...
Influence of the mesh size on plastic CTOD
Sanchez-Mancera, J.; Camas, D.; Prates, P. A.; Antunes, F. V.The fatigue crack growth rate is experimentally correlated to the applied range of stress intensity factor, ΔK. However, the crack growth is taking place in an area where there are significant plastic deformations. At the same time, ΔK is an elastic parameter that cannot predict the influence of the load stress ratios and load history. Elastic-Plastic Fracture Mechanics parameters such as the energy release rat...
Fatigue crack propagation analysis in 2024-T351 aluminium alloy using nonlinear...
Borges, M. F.; Lopez-Crespo, P.; Antunes, F. V.; Moreno, B.; Prates, P.; Camas, D.; Neto, D. M.In this work, fatigue crack growth (FCG) in the 2024-T351 aluminium alloy is studied using the plastic CTOD range, Δδp. Experimental tests were performed on 12 mm thick CT specimens in order to obtain FCG rate and in cylindrical specimens to obtain stress–strain loops. A numerical analysis replicated the experimental work in terms of material, geometry and loading conditions, but assuming pure plane strain stat...