Issue 48

V. Giannella et alii, Frattura ed Integrità Strutturale, 48 (2019) 639-647; DOI: 10.3221/IGF-ESIS.48.61 646 The corresponding load levels are those listed in Tab. 1 and, in particular, load step 1 (static load = 3 kN; cyclic load = ±24 kN) was applied for 15.000 fatigue cycles whilst load step 2 (static load = 12 kN; cyclic load = ±24 kN) was applied for 5.000 more fatigue cycles. Results for this test are shown in Fig. 9 showing a satisfactory agreement. (a) (b) Figure 9 : Results for Test II: (a) crack-growth rates; (b) DBEM crack-growth directions; experimental crack-growth direction shown in Fig. 4b. C ONCLUSIONS ruciform specimens subject to static loading in one direction and cyclic loading in the other orthogonal direction were simulated by a DBEM and a FEM code. Experimental tests were performed on cruciform specimens undergoing various combinations of static and cyclic loads. Regarding the DBEM, a peculiar procedure for crack propagation angle assessment was pointed out and the allowance for friction between crack faces was provided when required. The agreement among experimental and numerical results in terms of crack-growth rates and crack paths seems to be very good. R EFERENCES [1] Newman, Jr., J.C. and Raju, I.S. (1979). Analysis of surface cracks in finite plates under tension or bending loads, NASA TP-1578. [2] Wawrzynek, P.A., Carter, B.J. and Ingraffea, A.R. (2009). Advances in simulation of arbitrary 3d crack growth using FRANC3D/NG, in: Proceedings of the 12th international conference on fracture, Ottawa, Canada. [3] Bremberg, D. and Dhondt, G. (2009). Automatic 3 ‐ D crack propagation calculations: a pure hexahedral element approach versus a combined element approach, Int J Fract., 157, pp. 109 ‐ 118. DOI: 10.1007/s10704-009-9313-z. [4] Citarella, R., Lepore, M., Maligno, A. and Shlyannikov, V. (2015a). FEM simulation of a crack propagation in a round bar under combined tension and torsion fatigue loading, Frattura ed Integrità Strutturale, 31, pp. 138-147. DOI: 10.3221/IGF-ESIS.31.11. [5] Citarella, R., Giannella, V., Lepore, M. and Dhondt, G. (2018). Dual boundary element method and finite element method for mixed-mode crack propagation simulations in a cracked hollow shaft, Fatigue Fract Eng Mater Struct. 41, pp. 84-98. DOI: 10.1111/ffe.12655. [6] Citarella, R. and Cricrì, G. (2014). Three-dimensional BEM and FEM submodelling in a cracked FML full scale aeronautic panel, Appl. Compos. Mater., 21(3), pp. 557–577. DOI: 10.1007/s10443-014-9384-5. C