Difference between friction type and bearing type connection of high strength bolts
Datetime:2016.10.09 From:HanDan HaoQiang Fastener Manufacturing Co.,Ltd
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The high strength bolt connection is to clamp the plate parts through the large tightening pretension inside the bolt, which can produce large friction force, thus improving the integrity and stiffness of the connection. When the shear force is subjected to the different design and force requirements, it can be divided into two kinds of high strength bolt friction connection and high strength bolt bearing type connection. The essential difference between the two is the difference in the limit state. Although it is the same kind of bolt, it is very different in the calculation method, the requirement, the scope of application and so on. In the shear design, the friction type connection of high strength bolts is the maximum possible friction force provided by the bolt tightening force between the contact surfaces of the plate parts as the limit state, that is, to ensure that the shear force is not more than the maximum friction force during the whole operation. Relative slip deformation will not occur in the plate (the gap between the screw and the hole wall is always maintained), and the connecting plate is loaded according to the elastic whole. In the shear design, the shear strength of the high strength bolt allows the external shear to exceed the maximum friction force, and the relative slip deformation occurs between the connecting plates until the bolt rod contacts with the hole wall. After that, the connection depends on the shear of the bolt body and the pressure of the hole wall and the friction force between the contact surfaces of the plate. Finally, the bar body is cut. The failure of cut or hole wall is the ultimate state of shear connection. In a word, friction high-strength bolts and compressive high-strength bolts are actually the same bolts, but whether the design considers slip or not. The friction type high strength bolt can not slide, the bolt does not bear the shear, once the slip, the design is considered to reach the state of failure, the technology is more mature; the pressure type high strength bolt can slide, the bolt also bears the shear, and the final damage is equivalent to the failure of the ordinary bolt (bolt shear broken or steel plate crushed).
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