Issue 49

N. Kaddouri et alii, Frattura ed Integrità Strutturale, 49 (2019) 331-340; DOI: 10.3221/IGF-ESIS49.33 336 5 10 15 20 25 30 35 40 45 50 55 0,10 0,15 0,20 0,25 0,30 0,35 0,40 0,45 0,50 0,55 J-Integral (mj/mm²) Crack length (mm) [0] s [0 2 /15 2 /-15 2 /90 2 ] s [0 2 /30 2 /-30 2 /90 2 ] s [0 2 /45 2 /-45 2 /90 2 ] s [0 2 /60 2 /-60 2 /90 2 ] s [0 2 /75 2 /-75 2 /90 2 ] s Figure 6 : Variation J-Integral in function of the length of the crack for a different sequence of stacking. 0 5 10 15 20 25 30 35 40 45 50 55 6 8 10 12 14 16 Shear stress (MPa) Crack length (mm) [0] s [0 2 /15 2 /-15 2 /90 2 ] s [0 2 /30 2 /-30 2 /90 2 ] s [0 2 /45 2 /-45 2 /90 2 ] s [0 2 /60 2 /-60 2 /90 2 ] s [0 2 /75 2 /-75 2 /90 2 ] s Figure 7: Variation of the adhesive Shear Stress τ 23 in function of the the length of the crack for a different sequence of stacking. The distribution of shear stresses is the same whatever the sequence of stacking in the composite. The more low stresses are for the patch with a sequence of stacking [0 8 ]s this is due to the fact that the majority of stresses in the Adhesive are absorbed by the patch. For the other stacking sequences the transfer of stresses is minimal to the patch and therefore of high stresses in the adhesive. By analyzing, the peel stress according to the thickness of the patch. If the length of the crack is minimum than the width of the patch, the peel stresses value is identical, a maximum is on the side in contact with the adhesive and a minimum on the other face which is in contact with the plate. Only the sequence [0 2 ] 8 presents a continuity in the peel stress distribution since the different layers present the same properties and the same orientation of fiber, however for the other stacking sequences the stress distribution is in the