STUDY ON EFFECT OF BOLT'S HEAD OPENING ANGLE ON SLIP STRENGTH OF HIGH DURABILITY FRICTION GRIP JOINTS WITH HIGH STRENGTH COUNTERSUNK HEAD BOLTS

Abstract

This study focused on the opening angle of a countersunk head bolt which may have an effect on slip strength. By slip tests and Finite Element Analysis, it was found that as the opening angle increases from 90° to 96°, slip strength was improved. This is because as the opening angle increases, plastic deformation in the vicinity of the countersunk hole can be suppressed. Thereby the reduction in bolt axial force can also be suppressed. However, if the angle is more than 92° the bolt's head will be projecting from the surface of the splice plate. In such a case, the coating failure might be occurred, and corrosion durability will be decreased. Therefore, the optimum angle that can improve both slip strength and corrosion durability is 92°.