Issue 37

J. Kramberger et alii, Frattura ed Integrità Strutturale, 37 (2016) 153-159; DOI: 10.3221/IGF-ESIS.37.21 159 C ONCLUSIONS n this paper, the response of lotus-type porous material is investigated to biaxial loading that is applied with displacements rate control. It is shown that different pore morphology has some effect on multiaxial LCF-life, but only in form of statistical scatter band. It is shown that adjacent large pores are critical areas for crack formation and growth under given boundary conditions. Furthermore, it is shown, that with increase of crack length reaction force magnitude decreases towards zero. The tension/compression reaction force drops almost to zero, but shear reaction force remains at 0.3% of the initial shear reaction force. Possible explanation for this phenomenon are local bending-like conditions, which appear near large pores. Large pore radii then serve as stress relaxation areas. Presented numerical approach for low-cycle multiaxial fatigue failure study based on direct cyclic algorithm and inelastic strain energy is general and efficient. However, further research on modelling other general porous structures will be our tendency in this field. R EFERENCES [1] Banhart, J., Manufacture, characterisation and application of cellular metals and metal foams, Progress in Materials Science, 46 (2001) 559-632, DOI: 10.1016/S0079-6425(00)00002-5. [2] Smith, B., Szyniszewski, S., Hajjar, J., Schafer, B., Arwade, S., Steel foam for structures: A review of applications, manufacturing and material properties, Journal of Constructional Steel Research, 71 (2012) 1-10, DOI: 10.1016/j.jcsr.2011.10.028. [3] Lefebvre, L., Banhart, J., Dunand, D., Porous Metals and Metallic Foams: Current Status and Recent Developments, Advanced Engineering Materials, 10 (2008) 775-787, DOI: 10.1002/adem.200800241. [4] Vesenjak, M., Kovacic, A., Tane, M., Borovinsek, M., Nakajima, H., Ren, Z., C ompressive properties of lotus-type porous iron, Computational Materials Science, 65 (2012) 37-43, DOI: 10.1016/j.commatsci.2012.07.004. [5] Seki, H., Tane, M., Nakajima, H., Fatigue crack initiation and propagation in lotus-type porous copper, Materials Transactions, 49 (2008) 144-150, DOI: 10.2320/matertrans.MRA2007623. [6] Amsterdam, E., De Hosson, J., Onck, P., Failure mechanisms of closed-cell aluminum foam under monotonic and cyclic loading, Acta Materialia, 54 (2006) 4465-4472, DOI: 10.1016/j.actamat.2006.05.033. [7] Olurin, O., McCullough, K., Fleck, N., Ashby, M., Fatigue crack propagation in aluminium alloy foams, International Journal of Fatigue, 23 (2001) 375-382, DOI: 10.1016/S0142-1123(01)00010-X. [8] Zhou, J., Gao, Z., Cuitino, A., Soboyejo, W., Effects of heat treatment on the compressive deformation behavior of open cell aluminum foams, Materials Science and Engineering a-Structural Materials Properties Microstructure and Processing, 386 (2004) 118-128, DOI: 10.1016/j.msea.2004.07.042. [9] Seki, H., Tane, M., Nakajima, H., Effects of anisotropic pore structure and fiber texture on fatigue properties of lotus- type porous magnesium, Journal of Materials Research, 22 (2007) 3120-3129, DOI: 10.1557/JMR.2007.0385. [10] Seki, H., Tane, M., Otsuka, M., Nakajima, H., Effects of pore morphology on fatigue strength and fracture surface of lotus-type porous copper, Journal of Materials Research, 22 (2007) 1331-1338, DOI: 10.1557/jmr.2007.0164. [11] Vesenjak, M., Borovinšek, M., Fiedler, T., Higa, Y., Ren, Z., Structural characterisation of advanced pore morphology (APM) foam elements, Materials Letters, 110 (2013) 201-203, DOI: 10.1016/j.matlet.2013.08.026. [12] Vesenjak, M., Ren, Z., Ochsner, A., Dynamic behaviour of regular closed-cell porous metals – computational study, International Journal of Materials Engineering Innovation, 1 (2009) 175-196, DOI: 10.1504/IJMATEI.2009.029363. [13] Ingraham, M., DeMaria, C., Issen, K., Morrison, D., Low cycle fatigue of aluminum foam, Materials Science and Engineering a-Structural Materials Properties Microstructure and Processing, 504 (2009) 150-156, DOI: 10.1016/j.msea.2008.10.045 [14] Allison, P.G., Hammi, Y., Jordon, J.B., Horstemeyer, M.F., Modelling and experimental study of fatigue of powder metal steel (FC-0205), Powder Metallurgy, 56 (2014) 388-396, DOI: 10.1179/1743290113Y.0000000063. [15] Abaqus/CAE User's Manual (ver. 6.12), Dassaults Systemes Inc, 2011. [16] Kramberger, J., Šraml, M., Glodež, S., Computational study of low-cycle fatigue behaviour of lotus-type porous material, International Journal of Fatigue, In Press (2016), DOI: 10.1016/j.ijfatigue.2016.02.037. I