Study of Influence of Superimposed Hydrostatic Pressure on Ductility in Ring Compression Test

The effects of superimposed hydrostatic pressure on the ductility of compressed rings are investigated numerically by using the finite element method and employing the Johnson–Cook (J–C) model. The ductility and fracture strain increase considerably by imposing hydrostatic pressure, which delays the initiation of cracks at the corners of the rings. Furthermore, the sensitivity of the ductile fracture parameters in the J–C model on compressibility and crack initiation is considered. The effect of the shape factor on fracture in compressed rings under hydrostatic pressure is also investigated, and the predicted fracture strains are compared. Results show that fracture strain increases linearly with hydrostatic pressure regardless of the geometry of the rings. However, the initial value of fracture strain is small for tall rings. The numerical results are found to be in good agreement with experimental observations.