Issue 62

S.Ch.Djebbar et alii, Frattura ed Integrità Strutturale, 62 (2022) 304-325; DOI: 10.3221/IGF-ESIS.62.22

b=30 - a=2.5 [mm]

b=30 - a=10 [mm]

1

2

1

2

plate

Adhesive

Patch

b) Figure 14: a ) Traction curves associated with the geometric modification of the patch, and b) Stress levels in different substrates for two applied loads level. The stress level in the patch shows that regardless of the change made, the patch ensures the stress transfer of the damaged plate. The stress level in the adhesive shows that the stress distribution is practically the same regardless of the values of parameters ‘a’ and ‘b’. The rounding created at the corners of the patch improves the stress distribution in the adhesive and minimizes the stress concentration due to the patch-edge plate interaction. The maximum stresses are concentrated at the edges of the notch. These stresses increase with the increase of the applied load. Once the applied load reaches the value necessary to damage the adhesive during the load transfer, a zone of detachment appears at the edges; its size depends on the values of the two parameters ‘a’ and ‘b’. If the value parameters ‘a’ is high, the area of disbonding is more remarkable since it will have an interaction edge notch and a zone of fore stress concentration will be localized. This detachment zone propagates as the applied load increases. This causes low resistance vis-à-vis the tensile load when the value of parameter ‘a’ is significant.

Figure 15: Variation of the maximum tensile force and maximum displacement according to the geometric parameter “a” of the modification of the edges of the patch.

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