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L. Marsavina et alii, Frattura ed Integrità Strutturale, 34 (2015) 387-396; DOI: 10.3221/IGF-ESIS.34.43 395 criteria MTS, SED, Gmax, respectively ESIF, and a good agreement was observed. This allows to conclude that the theoretical fracture criteria developed for a solid material could be used with success to predict the crack propagation angles in cellular materials like PUR foams. Crack paths presented in Figs. 4 and 5 show that crack initiates in mixed mode or mode II, but grows to regain the symmetry and to eliminate mode II. 0 10 20 30 40 50 60 70 80 90 2.66 4 6 8 12 30  c [degrees] Support position S 2 [mm] ASCB specimens 100 145 300 Density 0 10 20 30 40 50 60 70 80 90 0 30 45 60 90  c [degrees] Loading angle [degrees] SEC specimens 100 145 300 Density a. ASCB specimens b. SEC specimens Figure 8 : Effect of density on crack initiation angle. A CKNOWLEDGMENTS his work was supported by a grant of the Romanian National Authority for Scientific Research, CNCS – UEFISCDI, project PN-II-ID-PCE-2011-3-0456, contract number 172/2011. Dr. E. Linul was partially supported by the strategic grant POSDRU/159/1.5/S/137070 (2014) of the Ministry of National Education, Romania, co-financed by the European Social Fund – Investing in People, within the Sectoral Operational Programme Human Resources Development 2007-2013. Dr. D.A. Apostol was partially supported by the strategic grant POSDRU/ POSDRU/159/1.5/S/137390/ (2014) of the Ministry of National Education, Romania, co-financed by the European Social Fund – Investing in People, within the Sectoral Operational Programme Human Resources Development 2007- 2013. R EFERENCES [1] Gibson, L.J., Ashby, M.F., Cellular solids, structure and properties, Second edition, Cambridge University Press, (1997). [2] Srivastava, V., Srivastava, R., On the polymeric foams: modeling and properties, J. Mater. Sci., 49 (2014) 2681-2692. [3] Marsavina, L., Fracture mechanics of foams, in H. Altenbach, A. Ochsner (Eds.), Cellular and porous materials in structures and processes, Springer, Wien, (2010) 1-46. [4] Marsavina, L., Constantinescu, D.M., Failure and damage in cellular materials, in H. Altenbach, T. Sadowski (Eds.), Failure and damage analysis of advanced materials, Springer, Wien, (2015) 119-190. [5] Huang, J.S., Gibson, L.J., Fracture toughness of brittle foams, Acta Metall. Mater., 39 (1991) 1627-1636. [6] Choi, S., Sankar, B.V. Fracture toughness of carbon foam, J. Compos. Mater., 37 (2003) 2101-2116. [7] Danielsson, M., Toughened rigid foam core material for use in sandwich construction, Cell. Polym., 15 (1996) 417- 435. [8] Viana, G.M., Carlsson, L.A., Mechanical properties and fracture characterisation of cross-linked PVC foams, J. Sandw. Struct. Mater., 4 (2002) 91-113. [9] Kabir, M.E., Saha, M.C., Jeelani, S., Tensile and fracture behavior of polymer foams, Mat. Sci. Eng. A-Struct., 429 (2006) 225-235. T