A Method to Determine the Plastic Bending Angle of Dowel-Type Fasteners

Abstract

In timber joints with dowel-type fasteners, the yield moment of the fastener is an important parameter. For fasteners of hardened steel, e.g. self-tapping screws, the yield moment cannot be calculated and has to be measured in a bending test as established in EN 409. The yield moment is defined at a plastic bending angle of α = 45°/d 0.7. Therefore, the determination of the plastic bending angle is important to derive the characteristic yield moment of fasteners. For a proper derivation of the fastener’s yield moment, the onset of plastic deformations must hence be identified in order to be able to determine the correct plastic bending angle. A new method for the determination of the plastic bending angle was developed which is independent of a ductile or brittle behaviour of the fastener. The method is generally applicable to different fastener types with various diameters.