PSI - Issue 5

Behzad V. Farahani et al. / Procedia Structural Integrity 5 (2017) 981–988 Behzad V. Farahani et al./ Structural Integrity Procedia 00 (2017) 000 – 000

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5. Concluding final remarks In this study, the fracture behaviour of a bi-failure specimen made of an Aluminium alloy AA6061-T6 was experimentally and computationally investigated. Meanwhile, the reaction force response in terms of the vertical displacement was evaluated in addition to the failure evolution in different modes of stress triaxialities. Experimentally, a non-contact full-field optical technique so- called “Digital Image Correlation - DIC” was employed to measure the displacement variations on the specimen surface. Using the acquired DIC data, it was possible to correlate the reaction force response (derived from the load cell) with the vertical displacement field at the central section of the specimen where the final failure mode occurred on. In order to assess the performance of numerical methods, the problem was solved using Finite Element Method formulation simulated in ABAQUS©. The geometrical properties and boundary conditions of the numerical model were considered as close as possible to the real model to accurately reproduce the experimental conditions. To simulate the failure phenomenon, a well-known failure criterion for ductile material behaviour, Gurson – Tvergaard – Needleman (GTN) was used to obtain numerical results. The force response with respect to the displacement field was thereby evaluated and compared to the experimental DIC solution. The numerical result was in a reasonable agreement with the experimental one, which allow to validate the proposed FE analysis. The first author truly acknowledges the funding provided by Ministério da Educação e Ciência, Fundação para a Ciência e a Tecnologia (Portugal), under grants PD/BD/114095/2015 and SFRH/BPD/111020/2015. Dr. Moreira acknowledges POPH - QREN-Tipologia 4.2 - Promotion of scientific employment funded by the ESF and MCTES. Authors gratefully acknowledge the funding of Project NORTE-01-0145-FEDER-000022 - SciTech - Science and Technology for Competitive and Sustainable Industries, cofinanced by Programa Operacional Regional do Norte (NORTE2020), through Fundo Europeu de Desenvolvimento Regional (FEDER). References Abendroth, M. & Kuna, M., 2006. Identification of ductile damage and fracture parameters from the small punch test using neural networks. Engineering Fracture Mechanics , 73(6), pp.710 – 725. Alves, M. & Driemeier, L., 2010. A Bi-Failure Specimen for Accessing the Performance of Failure Criteria. In IMPLAST . Basaran, M., 2011. Stress State Dependent Damage Modeling with a Focus on the Lode Angle Influence . Rheinisch Westflischen Technischen Hochschule Aachen. Benseddiq, N. & Imad, A., 2008. A ductile fracture analysis using a local damage model. International Journal of Pressure Vessels and Piping , 85(4), pp.219 – 227. Brünig, M., Gerke, S. & Hagenbrock, V., 2014. Stress-state-dependence of damage strain rate tensors caused by growth and coalescence of micro-defects. International Journal of Plasticity , 63, pp.49 – 63. C.H.L.J., Lambriks, M.P.J. & Unruh, K., 2009. Testing methods for fracture modelling. Tata Steel . Chaboche, J.-L., 1990. On the description of damage induced anisotropy and active/passive damage effect. In Damage Mechanics in Engineering Materials . pp. 159 – 166. Chen, J. et al., 2015. Improved extended digital image correlation for crack tip deformation measurement. Optics and Lasers in Engineering , 65, pp.103 – 109. Chu, C.C. & Needleman, A., 1980. Void Nucleation Effects in Biaxially Stretched Sheets. Journal of Engineering Materials and Technology , 102(3), p.249. Cintrón, R. & Saouma, V., 2008. Strain Measurements with the Digital Image Correlation System Vic-2D , Boulder. Driemeier, L. et al., 2015. A bifailure specimen for accessing failure criteria performance. International Journal of Plasticity , 71, pp.62 – 86. Acknowledgements