Strength Assessment Methods for Adhesively Bonded Repair

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Abstract Bonding is an attractive assembly solution in many ways. Indeed, it is a non-intrusive and cold solution enables to assemble mono or multi-material structures. This assembly technique is particularly interesting for the installation of equipment or repairs when welding is prohibited, such as in ATEX-type risk areas. For many years, COLD PAD has been developing bonded structural repair solutions and non-intrusive mechanical fasteners for marine environment. Their reinforcement product ColdShield™ [1], has been validated thanks to a previous collaboration with Bureau Veritas. From his side, Bureau Veritas is updating the guidance Note NI613 Adhesive Joints and Patch Repairs [2] to consider new development and innovation achieved in this technical domain. The objective of this paper is initially to present the different methods for evaluating the resistance of bonded assemblies proposed by Bureau Veritas. Two application cases of bonded repair will be detailed with the associated lessons learnt in terms of reliability. The first one concerns a conventional steel-steel bonded repair, one of studied applications within the framework of the JIP Strength Bond Offshore [3]. For this application, the stress approach and the combined stress-energy method will be explained as well as the use of cohesive elements for numerical simulations. The second one is the design assessment of the ColdShield™ reinforcement solution [4], which contributes to hull girder strength for Floating Production Storage and Offloading (FPSO) hull repair, and for which a stress approach is possible due to the specificity of the design. Results of both applications are analysed, compared and commented. In conclusion, the paper will highlight the importance of the calculation methodology and its robustness to avoid a misinterpretation of the strength.