Issue 42

M. Peron et alii, Frattura ed Integrità Strutturale, 42 (2017) 223-230; DOI: 10.3221/IGF-ESIS.42.24 229 being outside of this range). The few data which exceed the band fall however in the safety region of the plot. The averaged SED criterion appears suitable for fracture strength assessment of cracked specimens made out of Terfenol-D alloy, under mode I condition, in presence or absence of the magnetic field and with variable loading-rate. In the authors' opinion the result is satisfactory and the SED criterion permits the reliable assessment of Terfenol-D brittle failure by means of coarse mesh based finite element models. The proposed relationship between the size of the control volume and the loading-rate also permit to take into account the loading-rate by means of static analyses. Some future developments will involve also high temperature applications [26]. Figure 3 : Mean fracture loads as a function of the loading-rate and the magnetic field B. C ONCLUSIONS combined experimental and numerical study was conducted to understand the defect sensitivity of giant magnetostrictive materials. Under mode I loading condition, it has been found that Terfenol-D shows a decrease in fracture load in presence of a magnetic field. This behavior in justified by the increase of the strain energy with increasing magnetic fields. Terfenol-D also shows a decrease in fracture loads as the loading-rate decreases. Results indicate that SED criterion in able to capture this behavior if a linear relationship between the size of the control volume and the loading-rate is assumed. A good match between experimental results and numerical predictions has been found and a substantial mesh insensitivity of SED approach has been proved. R EFERENCES [1] Zhao, X., Lord, D.G., Application of the Villari effect to electric power harvesting, J. Appl. Phys., 99 (2006) 08M703 [2] Peterson, D.T., Verhoeven, J.D., McMasters, O.D., Spitzig, W.A., Strength of Terfenol-D. J. Appl. Phys., 65 (1989) 3712. [3] Lazzarin, P., Comportamento a fatica dei giunti saldati in funzione della densità di energia di deformazione locale: influenza dei campi di tensione singolari e non singolari, Frattura ed Integrità Strutturale, 9 (2009) 13-26. [4] Maragoni, L., Carraro, P. A., Peron, M. and Quaresimin, M., Fatigue behaviour of glass/epoxy laminates in the presence of voids, Int. J. Fatigue, 95 (2017) 18–28. [5] Brotzu, A., Felli, F. and Pilone, D., Effects of the manufacturing process on fracture behaviour of cast TiAl intermetallic alloys, Fract. Struct. Integr. 27 (2013), 66-73. [6] Narita, F., Morikawa, Y., Shindo, Y., Sato, M., Dynamic fatigue behavior of cracked piezoelectric ceramics in three- point bending under AC electric fields, J. Eur. Cera. Soc., 32 (2012) 3759–3766. [7] Ayatollahi, M.R., Razavi, S.M.J., Rashidi Moghaddam, M., Berto, F., Mode I fracture analysis of Polymethylmetacrylate using modified energy—based models. Phys. Mesomec., 18 (2015) 53-62. A