Effects of geometric parameters of screw type blind rivet joints on large blind head formation and pre-load

Abstract

Due to the labor-saving one-sided installation and little composite damage, screw type blind rivets are widely used for clinching composite structures in the aerospace field. However, there is a lack of comprehensive understanding of their setting process and the effects of geometric parameters on the large blind head formation and pre-load. In this paper, a 3D finite element model of a typical screw type blind rivet was built and validated by experimental results. According to the simulation results, it was found that the large blind head’s shape and pre-load were highly sensitive to the thickness ratio of insert and sleeve, the height ratio of insert and sleeve, the tapered angle of the nut body nose and the inclining angle, while the tapered angle of sheet and the height ratio of insert and sleeve’s inner stepped surface had relatively little impacts. Specifically, the thickness ratio, height ratio and nose angle had the suitable ranges, not within which an unqualified blind head with minor pre-load, small diameter, or (and) prohibited double flexures would occur. The pre-load is inversely proportional to inclining angle, whose optimum is 0°. In addition, the divided stages revealed the drop of pre-load caused by instability, while no instability took place in large thickness ratio. The accurate and reliable 3D model would build confidence in improving joint integrity and in further studying the failure mechanisms of joints, including loosening and composite damage.