Pressure calculation for preliminary formation of undercuts prone to defect of fold type

Abstract

The paper presents the calculation of the pressure at the first transition during the formation of the “undercuts” on which corrugation takes place. The formulas in general form for the stresses at the first transition and the required pressure depending on the length of the sweep are derived. The results with the finite element analysis of formation and field experiments are compared. The conclusions about the verification of the results are drawn.