PSI - Issue 2_A

M. Wicke et al. / Procedia Structural Integrity 2 (2016) 2643–2649 M. Wicke et al./ / Structural Integrity Procedia 00 (2016) 000–000

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kind of a dendritic structure. In order to investigate the structural influence of the pores, their geometry was converted into 3D volumetric models. A deviation analysis indicated the precise conversion of the surface geometry of each pore revealed by μ-CT, ensuring the accurate consideration of the real 3D morphology in the numerical computation. The pores, inserted in a finite element model of a cylindrical volume, were rotated simultaneously around the axes of a coordinate system centered in the pore center of gravity to localize regions of elevated stress in dependency of the load direction. Results indicate that the peak stress concentration is particularly located in a hole on the defect geometry, which can thus be identified as hot spots. The automatization of the numerical treatment provides a comfortable investigation of additional casting defects reconstructed in terms of highly stressed regions, which could be used for a fracture mechanics assessment. Further work should focus on advanced methods such as the extended finite element method (XFEM) for analyzing the propensity of these defects towards crack initiation. 5. Acknowledgements The authors would like to thank the Hessen State Ministry of Higher Education, Research and the Arts - Initiative for the Development of Scientific and Economic Excellence (LOEWE) - for financial support of the special research project “Safer Materials”. 6. References Ashtari, P., Tezuka, H., Sato, T., 2003. Influence of Sr and Mn Additions on Intermetallic Compound Morphologies in Al-Si-Cu-Fe Cast Alloys. Materials Transactions 44, 2611-2616. Buffière, J-Y., Savelli, S., Jouneau, P.H., Maire, E., Fougères, R., 2001. Experimental study of porosity and its relation to fatigue mechanisms of model Al-Si7-Mg0.3 cast Al alloys. Materials Science and Engineering A316, 115-126. Couper, M.J., Neeson, A.E., Griffiths, J.R., 1990. CASTING DEFECTS AND THE FATIGUE BEHAVIOUR OF AN ALUMINIUM CASTING ALLOY. Fatigue & Fracture of Engineering Materials & Structures 13, 213–227. Dinnis, C.M., Taylor, J.A., Dahle, A.K., 2006. Iron-related porosity in Al-Si-(Cu) foundry alloys. Materials Science and Engineering A425, 286 296. Ferrié, E., Buffière, J.-Y., Ludwig, W., 2005. 3D characterisation of the nucleation of a short fatigue crack at a pore in a cast Al alloy using high resolution synchrotron microtomography. International Journal of Fatigue 27, 1215-1220. Gao, Y.X., Yi, J.Z., Lee, P.D., Lindley, T.C., 2004. The effect of porosity on the fatigue life of cast aluminium-silicon alloys. Fatigue & Fracture of Engineering Materials & Structures 27, 559-570. Li, P., Lee, P.D., Lindley, T.C., Maijer, D.M., Davis, G.R., Elliot, J.C., 2006. X-ray Microtomographic Characterisation of Porosity and its Influence on Fatigue Crack Growth. Advanced Engineering Materials 8, 476-479 Lu, L., Dahle, A.K., 2005. Iron-Rich Intermetallic Phases and Their Role in Casting Defect Formation in Hypoeutectic Al-Si Alloys. Metallurgical and Materials Transactions A36, 819-835. Nicoletto, G., Konečná, R., Fintova, S., 2012. Characterization of microshrinkage casting defects of Al-Si alloys by X-ray computed tomography and metallography. International Journal of Fatigue 41, 39-46. Puncreobutr, C., Lee, P.D., Kareh, K.M., Connolley, T., Fife, J.L., Phillion, A.B., 2014. Influence of Fe-rich intermetallics on solidification defects in Al-Si-Cu alloys. Acta Materialia 68, 42-51. Skallerud, B., Iveland, T., Härkegård, G., 1993. Fatigue life assessment of aluminum alloys with casting defects. Engineering Fracture Mechanics 44, 857-874. Taylor, J.A., Schaffer, G.B., StJohn, D.H., 1999. The Role of Iron in the Formation of Porosity in Al-Si-Cu-Based Casting Alloys: Part I. Initial Experimental Observations. Metallurgical and Materials Transactions A30, 1999-1643. Vanderesse, N., Maire, É., Chabod, A., Buffière, J.-Y., 2011. Microtomographic study and finite element analysis of the porosity harmfulness in a cast aluminium alloy. International Journal of Fatigue 33, 1514-1525. Wang, Q.G., Apelian, D., Lados, D.A., 2001. Fatigue behavior of A356-T6 aluminum cast alloys. Part I. Effect of casting defects. Journal of Light Metals 1, 73-84. Yi, J.Z., Gao, Y.X., Lee, P.D., Lindley, T.C., 2004. Effect of Fe-content on fatigue crack initiation and propagation in a cast aluminum–silicon alloy (A356–T6). Materials Science and Engineering A386, 396-407.