Issue 49

N. Kaddouri et alii, Frattura ed Integrità Strutturale, 49 (2019) 331-340; DOI: 10.3221/IGF-ESIS49.33 335 Figure 4 : Mesh details of repaired plate. 0 10 20 30 40 50 0 2 4 6 8 10 12 14 J-Integral (mj/mm²) Crack length (mm) Plate unrepaired Plate repaired Figure 5: Variation of the J-Integral as a function of the length of the crack to the damaged plates and repaired by composite patch. The choice of the laminate sequence for a patch is also important. For this we took 6 laminated with different fibers orientation ( see Tab. 4), the variation of the J-Integral is similar whatever the sequence of stacking, the value of the J- Integral is low for the patch that has the sequence [0] 8 ,this value increases if the sequence of the patch is [0 2 /75 2 /- 75 2 /90 2 ]s, for the laminate sequence [0] 8 the patch has the highest mechanical properties according to the loading direction and thus absorbed more stresses. However, if the fibers orientation angle tends toward 90°, the mechanical properties of the patch are declining and therefore less of load transfer from the damaged area. If the length of the crack is too small than the width of the plate, the effect of the sequence of stacking disappears. The J-Integral increases with the increase in the size of crack. The lowest values of the J-Integral are noted for the case of repair by patch for which the sequence of stacking is [0 8 ]s, for this orientation the composite presents the mechanical properties high and therefore a better transfer of charge of the damaged plate through the adhesive.