Issue 49

B. El-Hadi et alii, Frattura ed Integrità Strutturale, 49 (2019) 547-556; DOI: 10.3221/IGF-ESIS.49.51 555 As expected above by analyzing the distribution of stress intensity factors, Fig. 12.a shows that the fatigue lifetime obtained from using of the stress intensity factor (avg-all) and to a lesser extent the results obtained from using the (avg- 9.mid) , (K.mid) and (avg-K.rms) respectively, gives a precise results for the case of thin repaired plates .This is evident through a good agreement of FEM curve results obtained from (avg-all) with experimental curve. On another side, Fig.12.b shows that the values obtained from the root mean square stress intensity factor (avg-K.rms) and to a lesser extent obtained from the (K.mid), (avg-9 .mid) and (avg-all), respectively gives precise results for the case of the thick repaired plates. this is evidenced by the good agreement of the numerically obtained lifetimes with those obtained experimentally. C ONCLUSION his study focused on the fatigue crack growth behavior of center cracked aluminum plate repaired asymmetrically with bonded composite patch .The analysis led to the following conclusions: - The stress at the crack tip in the patched side of the plate is much smaller than that in the un-patched side of the plate. - The maximum length of crack whose position exactly corresponds to the position for the maximum value of stress intensity factor. - The crack front shape differs between the thin and thick plates. - Reliance on the stress average all (avg-all) in the calculate the fatigue life of the thin plates repaired asymmetrically. Showed excellent accuracy compared with experimentally reverse thick plates which the stress root mean square (K.rms). R EFERENCES [1] Baker, A.A., Rose, L.R.F., Jones, R. (2002). Advances in the bonded composite repair of metallic aircraft structure, Killington, Elsevier Publications. [2] Bianchi, R. W., Kwon, Y. W., Alley, E. S. (2019). Composite Patch Repair for Underwater Aluminum Structures, Journal of Offshore Mechanics and Arctic Engineering, 141(6), p. 064501. DOI: 10.1115/1.4042940. [3] Umamaheswar, T.V.R.S., Ripudaman, S. (1999). Modelling of a patch repair to a thin cracked sheet, Eng Fract Mech., 62(2-3), pp. 267-289. DOI: org/10.1016/S0013-7944(98)00088-5. [4] Mahadesh, K.A., Hakeem, S.A. (2000). Optimum design of symmetric composite patch repair to center cracked metallic sheet, Compos Struct. 49(3), pp. 285–292. DOI:org/10.1016/S0263-8223(00)00005-2. [5] Brighenti, R. (2007). Patch repair design optimization for fracture and fatigue improvements of cracked plates. Solids Struct. 44(3-4), pp. 1115–1131. DOI: org/10.1016/j.ijsolstr.2006.06.006. [6] Rachid, M., Serier, B., Bachir Bouiadjra, B., Belhouari, M. (2012). Numerical analysis of the patch shape effects on the performances of bonded composite repair in aircraft structures, Compos B: Eng. 43(2), pp. 391–397. DOI: org/10.1016/j.compositesb.2011.08.047. [7] Bachir Bouiadjra, B., Fari Bouanani, M., Albedah, A., Benyahia, F., Es-Saheb M., (2011). Comparison between rectangular and trapezoidal bonded composite repairs in aircraft structures: a numerical analysis, Mater Des. 32(6), pp. 3161–3166. DOI: org/10.1016/j.matdes.2011.02.053. [8] Kashfuddoja, M., Ramji, M. (2014). Design of optimum patch shape and size for bonded repair on damaged Carbon fibre reinforced polymer panels, Mater Des. 54, pp. 174-183. DOI: org/10.1016/j.matdes.2013.08.043. [9] Soutis, C., Hu, F.Z. (1997). Design and performance of bonded patch repairs of composite structures, Proc Inst Mech Eng G: Aerospace Eng. 211(4), pp. 263–271. DOI:org/10.1243/0954410971532668. [10] Besseghier, E.H., Djebli, A., Bendouba, M., Aid, A. (2017). Effect of Patch Shape on the Repair Efficiency of a Cracked Aluminum Panel, Materials and Engineering Structures, 4, pp. 225–233. [11] Shiuh-Chuan, H., Chao, M.N. (2011). Adhesively bonded patch repair of composite laminates, Adhes Sci Technol. 25(18), pp. 2569–2585. DOI: org/10.1163/016942411X580234. [12] Turaga, V.R.S., Ripudiman, (1999). Modeling of patch repairs to a thin cracked sheet. Engn. Fract. Mec. 74, pp. 431- 443. [13] Cheng, P., Xiao-Jing, G., Hearn, D., Aivazzadeh, S. (2011). Tensile behaviour of patch- repaired CFRP laminates, Compos Struct. 93(2), pp. 582–589. DOI: org/10.1016/j.compstruct.2010.08.021. T