Enhancement of plastic flow in lateral direction by torsional oscillation in upsetting and lateral extrusion

Mechanical Modelling of the Plastic Flow Machining Process

Materials ◽

10.3390/ma11071218 ◽

2018 ◽

Vol 11 (7) ◽

pp. 1218 ◽

Cited By ~ 4

Author(s):

Viet Vu ◽

Yan Beygelzimer ◽

Roman Kulagin ◽

Laszlo Toth

Keyword(s):

Finite Element ◽

Hydrostatic Pressure ◽

Plastic Flow ◽

Deformation Gradient ◽

Back Pressure ◽

Extrusion Ratio ◽

Finite Element Simulations ◽

Analytical Modelling ◽

Lateral Extrusion ◽

Lateral Channel

A new severe plastic deformation process, plastic flow machining (PFM), was introduced recently to produce sheet materials with ultrafine and gradient structures from bulk samples in one single deformation step. During the PFM process, a part of a rectangular sample is transformed into a thin sheet or fin under high hydrostatic pressure. The obtained fin is heavily deformed and presents a strain gradient across its thickness. The present paper aims to provide better understanding about this new process via analytical modelling accompanied by finite element simulations. PFM experiments were carried out on square commercially pure aluminum (CP Al) billets. Under pressing, the material flowed from the horizontal channel into a narrow 90° oriented lateral channel to form a fin sheet product, and the remaining part of the sample continued to move along the horizontal channel. At the opposite end of the bulk sample, a back-pressure was applied to increase the hydrostatic pressure in the material. The experiments were set at different width sizes of the lateral channel under two conditions; with or without applying back-pressure. A factor called the lateral extrusion ratio was defined as the ratio between the volume of the produced fin and the incoming volume. This ratio characterizes the efficiency of the PFM process. The experimental results showed that this ratio was greater when back-pressure was applied and further, it increased with the rise of the lateral channel width size. Finite element simulations were conducted in the same boundary conditions as the experiments using DEFORM-2D/3D software, V11.0. Two analytical models were also established. The first one used the variational principle to predict the lateral extrusion ratio belonging to the minimum total plastic power. The second one employed an upper-bound approach on a kinematically admissible velocity field to describe the deformation gradient in the fin. The numerical simulations and the analytical modelling successfully predicted the experimental tendencies, including the deformation gradient across the fin thickness.

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Lateral Extrusion of A6063 Pipes with a Lost Core of Alumina Powder Bonded with Wax

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.523-524.1006 ◽

2012 ◽

Vol 523-524 ◽

pp. 1006-1011

Author(s):

Takahiro Ohashi ◽

Ngoquang Thanh ◽

Ryosuke Miyajima

Keyword(s):

Low Temperature ◽

Extrusion Process ◽

Core Material ◽

Alumina Powder ◽

Mixing Ratio ◽

Lateral Direction ◽

Lateral Extrusion ◽

Melting Material ◽

Alumina Ball ◽

Temperature Melting

The authors have developed a lateral extrusion process with a lost core. The outline of the process is as follows. First, the cavity of a pipe, or a channel material, is filled up with liquid of a low-temperature melting material. The low-temperature melting material is then solidified to become a soluble core of the pipe. The authors call this soluble core the lost core. Next, the material is compressed longitudinally as a composite billet and extruded in the lateral direction. After deformation, the low-temperature melting material is melted and removed. The process can performed in a compression state to control the precise appearance of the product. This study examines a new core material, alumina powder (alumina ball) bonded with wax, as a core material. A mixing methodology for wax and alumina powder is discussed along with the effect of their mixing ratio on the deformation of the pipe.

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ANALYSIS OF TEMPERATURE DISTRIBUTION AND PLASTIC FLOW DURING SPOT FRICTION STIR WELDING

Equipment ◽

10.1615/ihtc13.p13.30 ◽

2006 ◽

Cited By ~ 1

Author(s):

S. Hirasawa ◽

K. Okamoto ◽

S. Hirano ◽

T. Tomimura

Keyword(s):

Friction Stir Welding ◽

Temperature Distribution ◽

Plastic Flow ◽

Friction Stir

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Fore-Aft Forces in Tire-Wheel Assemblies Generated by Unbalances and the Influence of Balancing

Tire Science and Technology ◽

10.2346/1.2141713 ◽

1991 ◽

Vol 19 (3) ◽

pp. 142-162 ◽

Cited By ~ 4

Author(s):

D. S. Stutts ◽

W. Soedel ◽

S. K. Jha

Keyword(s):

Mathematical Model ◽

Elastic Foundation ◽

Torsional Oscillation ◽

Vertical Direction ◽

Torsional Stiffness ◽

Rolling Motion ◽

Vertical Force ◽

Horizontal Force ◽

Wheel Rim ◽

Open Question

Abstract When measuring bearing forces of the tire-wheel assembly during drum tests, it was found that beyond certain speeds, the horizontal force variations or so-called fore-aft forces were larger than the force variations in the vertical direction. The explanation of this phenomenon is still somewhat an open question. One of the hypothetical models argues in favor of torsional oscillations caused by a changing rolling radius. But it appears that there is a simpler answer. In this paper, a mathematical model of a tire consisting of a rigid tread ring connected to a freely rotating wheel or hub through an elastic foundation which has radial and torsional stiffness was developed. This model shows that an unbalanced mass on the tread ring will cause an oscillatory rolling motion of the tread ring on the drum which is superimposed on the nominal rolling. This will indeed result in larger fore-aft than vertical force variations beyond certain speeds, which are a function of run-out. The rolling motion is in a certain sense a torsional oscillation, but postulation of a changing rolling radius is not necessary for its creation. The model also shows the limitation on balancing the tire-wheel assembly at the wheel rim if the unbalance occurs at the tread band.

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Features of plastic flow of sintered Al-12Si-xSn alloys

Physics and Chemistry of Materials Treatment ◽

10.30791/0015-3214-2018-6-48-59 ◽

2018 ◽

pp. 48-59

Author(s):

N.M. Rusin ◽

◽

A.L. Skorentsev ◽

Keyword(s):

Plastic Flow

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MANUFACTURE INVESTIGATION OF CARTRIDGE WITH BOTTOM-MOST PART FLANGE BY DIRECT EXTRUSION WITH COUNTERPUNCH. REPORT 13. DETERMINATION OF DEFORMED STATE UNDER STRAITENED EXTRUSION IN FOURTH CENTRAL AREA OF PLASTIC DEFORMATION

Technology of metals ◽

10.31044/1684-2499-2020-0-4-43-51 ◽

2020 ◽

Vol 0 (4) ◽

pp. 43-51

Author(s):

A. L. Vorontsov ◽

◽

I. A. Nikiforov ◽

Keyword(s):

Plastic Deformation ◽

Plastic Flow ◽

Central Area ◽

Direct Extrusion ◽

Deformed State ◽

Cumulative Deformation ◽

The Given ◽

General Method

Formulae have been obtained that are necessary to calculate cumulative deformation in the process of straitened extrusion in the central area closed to the working end of the counterpunch. The general method of plastic flow proposed by A. L. Vorontsov was used. The obtained formulae allow one to determine the deformed state of a billet in any point of the given area. The formulae should be used to take into account the strengthening of the extruded material.

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