Contents lists available at ScienceDirect Engineering Fracture Mechanics journal homepage: www.elsevier.com/locate/engfracmech Mechanical characterization of the AlSi9Cu3 cast alloy under distinct stress states and thermal conditions S. Gain a,b , T.E.F. Silva a,b , A.M.P. Jesus a,b, ⁎ , A. Cavaleiro a , P.A.R. Rosa c , A. Reis a,b a INEGI, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal b Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal c IDMEC, Instituto Superior Técnico, University of Lisbon, 1 Av. Rovisco Pais, 1049-001 Lisboa, Portugal ARTICLE INFO Keywords: AlSi9Cu3 cast alloy Mechanical testing Constitutive modelling Plasticity Damage ABSTRACT This paper presents the results of several mechanical tests aiming at characterizing the con- stitutive behaviour of the AlSi9Cu3 cast alloy, covering different temperatures and stress fields, including tensile and compressive tests of smooth and notched specimens as well as combined shear/tension and shear/compression with special designed specimens. The Johnson-Cook model was able to correlate the flow stress under quasi-static uniaxial compression, including thermal effects. However, under tension the yield stress does not reduces monotonically and gradually with temperature, which impedes the application of Johnson-Cook model for positive triaxial- ities. At room temperature, the AlSi9Cu3 alloy shows significant asymmetrical tensile and compressive behaviours requiring a plasticity model sensitive to the stress triaxiality such as the Drucker-Prager. As regards the ductility limits of the material, different data was analysed to generate fracture loci for the material where equivalent fracture strains were plotted against the stress triaxialities. The calibrated Drucker-Prager constitutive model together with a damage approach based on the fracture loci generated was successfully verified using test data from specimens loaded under combined shear/tension or shear/compression. The AlSi9Cu3 cast alloy exhibits a sharp reduction in ductility between the negative stress triaxiality cut-off and -0.1, keeping at low levels above this triaxiality value. 1. Introduction Environmental and governmental pressure to decrease fuel consumption and emissions in transportation, particularly in the automotive and aerospace industry, has challenged the main manufacturers to find solutions either by changing to lighter alloys as well as by using unconventional geometries of components. These challenges have pushed engineers to develop and optimize pro- cesses, particularly related to aluminium alloys [1]. Aluminium alloys are being used intensively in the automotive, aerospace and marine industries due to their low weight, high specific strength, high wear resistance, good corrosion resistance, high chemical inactivity and suitable mechanical properties at ambient and moderate temperatures, while allowing to be processed easily by inexpensive manufacturing processes. Casting is one of the main processes utilized for the production of parts made of aluminium alloys, because: (i) allows the production of complex parts; (ii) requires small amount of post processing; (iii) is a cost-efficient process for large series production; and (iv) allows materials recycling (recasting). The European Union is highly interested in the secondary or recycled aluminium https://doi.org/10.1016/j.engfracmech.2019.106499 Received 17 January 2019; Received in revised form 9 May 2019; Accepted 29 May 2019 ⁎ Corresponding author. E-mail address: ajesus@fe.up.pt (A.M.P. Jesus). Engineering Fracture Mechanics xxx (xxxx) xxxx 0013-7944/ © 2019 Elsevier Ltd. All rights reserved. Please cite this article as: S. Gain, et al., Engineering Fracture Mechanics, https://doi.org/10.1016/j.engfracmech.2019.106499