On the numerical prediction of the torque-to-turn-value of a blind rivet nut

© 2019, Springer-Verlag France SAS, part of Springer Nature. In the present paper, finite element simulations are used to gain a better understanding of the setting process of a blind rivet nut. A blind rivet nut is a mechanical fastener capable of clinching materials whilst providing a threaded solution without the need for thread forming. The technique relies on plastic deformation introduced by axial compression of the rivet nut in such a way that a counter head is formed on the opposite side of the work piece. For certain applications, stresses in the plate material induced by the setting process are detrimental for the fastener’s integrity. Hence an improved design of the fastener is desired. To embark on such a redesign, an appropriate numerical model to reveal the influence of several parameters is indispensable. In this work, a strategy is presented to simulate the setting process involving large plastic strains and contact pressures. An FE based inverse method was used to identify the local plastic material properties of the blind rivet nut. The forming simulation was validated in terms of predicted shape of the rivet nut and the evolution of the setting force. A quasi-static FE model using the shape and solution variables of the deformed rivet nut was used to reproduce the torque-to-turn resistance as a function of the setting force. The strategy was successfully applied on two blind rivet nuts, different in geometry and base material. Finally, three industrial case studies confirmed the viability of the model.

Publication year:2019

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Authors from:Private, Higher Education

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