Study of Influence of Superimposed Hydrostatic Pressure on Ductility in Ring Compression Test
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Study of Influence of Superimposed Hydrostatic Pressure on Ductility in Ring Compression Test Amir Partovi
, M.M. Shahzamanian, and P.D. Wu
(Submitted February 13, 2020; in revised form July 7, 2020) 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. Keywords
compressibility, finite element analysis fracture, superimposed hydrostatic pressure
(FEA),
1. Introduction Axial compression tests have been widely used in the past few decades to analyze the structural behavior of workpieces under static loading, in which the material experiences large plastic deformations to obtain a desirable shape, such as in metal forming. The mechanical properties of metals can be investigated through a compression test. The effects of hydrostatic pressure on ductility have been experimentally studied. However, to the best of our knowledge, the effects of superimposed hydrostatic pressure on the fracture and compressibility of metal rings have not been considered numerically in detail elsewhere. The ring compression test was originally introduced by Kunogi (Ref 1) to determine friction. Male and Cockcroft (Ref 2) modified this technique by introducing calibration curves on the basis of the deformation of a compressed ring. They used a ring geometric ratio of 6:3:2 (outer diameter:inner diameter:height, OD:ID:H), which was subsequently used as the standard geometry for ring compression tests. Avitzur (Ref 3) presented a mathematical analysis of the ring compression test and proposed a relation for the friction factor based on ring geometry. Ring compression tests for various geometries and industrially important materials have been performed by many researchers in the last three decades, and numerous review papers emphasizing the technique have been published (Ref 49). Increasing the formability of metal workpieces has always been interesting to the industry and to researchers. There are Amir Partovi, M.M. Shahzamanian, and P.D. Wu, Department of Mechanical Engineering, McMaster University, Hamilton, ON L8S 4L7, Canada. Contact e-mails: [email protected] and [email protected].
Journal of Materials Engineering and Perf
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