Issue 35

R. Citarella, Frattura ed Integrità Strutturale, 35 (2015) 523-533; DOI: 10.3221/IGF-ESIS.35.58 532 da c (mm) K G (MPa*mm 1/2 ) K R (MPa*mm 1/2 ) 0.0 1829 680 0.7 1823 1176 1.8 1828 1421 2.8 1842 1611 3.7 1870 1755 4.6 1908 1875 5.3 1968 1956 5.7 2063 2006 5.9 2198 2026 Table 2 : K R , K G data for the crack tip N. 1 ( K G calculated with Irwin correction). C ONCLUSIONS he procedure presented turn out to be a very effective way to model the assembly and exhibits a satisfactory agreement with experimental results, very attractive run times and an easy pre-processing phase (the mesh generation is very easy because based on monodimensional elements). The main advantages of the proposed DBEM two-dimensional approach to lap joint modelling are [see also 15-16]: each layer can be considered as an individual two-dimensional structure; individual layers can be explicitly modelled and connected with rivets (in case of need this provide a way to enhance the accuracy with respect to the simplified approach adopted in this work); the determination of the SIFs is straightforward with the J-integral technique; rivets can be modelled as separate DBEM zones, interacting with the main zone by gap elements (in case of nonlinear contact analysis) or by interface spring of negligible stiffness (to disconnect the pin-hole interface) or by simply enforcing continuity conditions. B IBLIOGRAPHY [1] Broek, D., The Effects of Multi-Site-Damage on the Arrest Capability of Aircraft Fuselage Structures , FractuREsearch, TR 9302, (1993). [2] Nesterenko, GI., Multiple site fatigue damages of aircraft structures, NASA, N96-24270, (1995). [3] Samavedam, G., Hoadley, D., Thomson, D., Full-scale testing and analysis of curved aircraft fuselage panels. FAA, DOT/FAA/CT- 93/78 (1993). [4] ASTM ES61-94, Standard practice for r-curve determination for simple metal sheets, Annual book of ASTM standard, , American Society for Testing and Materials, Philadelphia, (2010) B42 - B60. [5] DeWit, R., Fields, R. J., Low III, S. R., Harne, D. E., Foecke, T., Fracture Testing of large-Scale Thin-Sheet Aluminum Alloy , DOT/FAA/AR-95/11, Federal Aviation Administration, (1996). [6] Calì, C., Citarella, R., Residual strength assessment for a butt joint in MSD condition, Advances in Engineering Software, 35 (2004) 373-382. [7] Silva, L. F. M., Gonçalves, J. P. M., Oliveira, F. M. F., de Castro, P. M. S. T., Multiple-site damage in riveted lap- joints: experimental simulation and finite element prediction, International Journal of Fatigue, 22 (4) (2000) 319-338. [8] Citarella, R., Cricrì, G., Armentani, E., Multiple crack propagation with Dual Boundary Element Method in stiffened and reinforced full scale aeronautic panels, Key Engineering Materials, 560 (2013) 129-155. [9] Calì, C., Citarella, R., Perrella, M., Three-dimensional crack growth: numerical evaluations and experimental tests, European Structural Integrity Society, Biaxial/Multiaxial Fatigue and Fracture, Eds. A. Carpinteri, M. de Freitas, A. Spagnoli, 31 (2003) 341-360. [10] Citarella, R., Perrella, M., Multiple surface crack propagation: numerical simulations and experimental tests, Fatigue and Fracture of Engineering Material and Structures, 28 (2005) 135-148. [11] BEASY V10r14, Documentation, C.M. BEASY Ltd; (2011). [12] Citarella, R., Non Linear MSD crack growth by DBEM for a riveted aeronautic reinforcement, Advances in Engineering Software, 40 (4) (2009) 253–259.