PSI - Issue 38

248 Hamza Abbad El Andaloussi et al. / Procedia Structural Integrity 38 (2022) 238–250 Hamza Abbad El Andaloussi, Luc Mouton, Firas Sayed Ahmad, Xabier Errotabehere, Stéphanie Mahérault-Mougin, Stéphane Paboeuf/ Structural Integrity Procedia 00 (2021) 000 – 000 11 The interfacial design S-N curve is calculated based on the below main conditions: • 25 tensile fatigue tests ; • A probability of failure 2.50% and a confidence level of 90%; • The S-N curve parameters are determined between 10 3 and 10 7 cycles. The coefficients of the interfacial design S-N curve are: • m = 9.78 • log(K P ) = 13.86 Figure 8 presents design S-N curve for the studied bonded reinforcement (called “ColdShield - Metal”):

Figure 8 Interfacial linearized DESIGN S-N curve for bonded reinforcement

This interfacial design S-N curve is then used to determine the fatigue life of the bonded reinforcements installed on-site. 6. Discussion and conclusion 6.1. Representativeness and robustness of the approach It is well known that bonded assemblies’ strength is dependent of the adhesive thickness Erreur ! Source du renvoi introuvable. . Therefore, full-scale specimens have been manufactured in terms of edifice: • The reinforcement exhibits a full-scale thickness; • The adhesive injected to bond the reinforcement to the steel substrate exhibits a nominal thickness of 5 mm in the leading edge. So, it should be noted that the final S-N curve, which constitutes the main outcome of this work, is strictly applicable for this bonded reinforcement exhibiting a nominal adhesive thickness. Additionally, the representativeness of this work is to be highlighted as the installation process of this specimen follows the industrial process: • Manufacturing is fully controlled in factory and witnessed by Classification society; • Surface preparation of the steel substrate follows offshore surface preparation standards controlling degree of cleanliness, dust level, surface salinity and roughness; • The injection process (allowing to bond the reinforcement onto the steel substrate) done in this work is exactly the same as the one done offshore. It uses a tailor-made vacuum assisted injection machine that controls the humidity level between the reinforcement and the substrate around 1% RH during the bonding. In other words, the full sequence (reinforcement manufacturing, steel substrate surface preparation, reinforcement bonding) is representative of an offshore installation. For the tested specimens, the adhesive is in contact with air with a lab humidity level, while the adhesive of the assemblies installed offshore is protected from marine environment and any moisture by the peripheral