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The present paper derives best practices to accurately simulate the installation process of a Blind Rivet Nut (BRN) using FEA. A BRN is a mechanical fastener used to equip plate material with a threaded part. The installation of a BRN inherently induces a high contact force which can have detrimental consequences when applied to non-metals such as polymer composite materials. The effects of the localized stress in the plate on the mechanical performance of the BRN can be studied with the aid of finite element simulations. To this end, the joining by forming process itself is accurately simulated using a computational efficient axisymmetric 2D model. The 2D model enables to predict the metal flow and internal state of stress after setting with sufficient accuracy. The latter is validated using a full 3D model and a multitude of experimental observations. It is shown that the large strain flow curve of the BRN material needs to be adequately identified. An industrially relevant calibration procedure is presented mitigating the experimental effort. In addition, material test selection in case of highly anisotropic BRN Van de Velde A.

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Weight reduction is often a key factor in modern mechanical design, therefore materials such as carbon fibre reinforced plastics (CFRP) are increasingly used and integrated within multi-material structures using adhesive technologies, which require high effort and are difficult to disassemble. The capability of a blind rivet nut (BRN) to join different materials without these disadvantages has created a growing industrial interest in the fastener. However, installing a BRN in CFRP laminate induces a significant stress concentration in the plate, which potentially causes damage. Given that ‘damage free’ joints are demanded by the industry, the BRN is often not considered as a suitable joining technique. In the present research, an experimental campaign is performed to investigate the fatigue resistance of a BRN joint in CFRP. It is demonstrated that the resulting compressive stress after installing a BRN can enhance the fatigue resistance of the specimen. The results increase the potential of the BRN as a fastener for CFRP.

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