Initial plastic yielding in notch bend tests

Abstract

T heoretical plane-strain solutions are presented for the initial plastic yielding of notched bars bent either under four-point loading or as in the Izod or Charpy tests, and having either a V notch or a notch whose root is a circular arc. These solutions provide estimates of the stresses in the plastic regions, the mode of yielding, and the corresponding yield-point loads. Calculations are made of the maximum tensile stress below the notch root and of the smallest depth of notch for which initial yielding does not extend to the notched surface. The theoretical solutions are confirmed by experimental observations of the yield-point loads in slow bend tests, and of the modes of deformation in slow and impact tests ; the latter are found to be very similar. The ductility transition is discussed in relation to this and other work.