Plastic flow pressure

Collapse and Bursting Pressure. If the pressure is sufficiently large to push the plastic—elastic boundary to the outer surface of the cylinder so that the fibers at that surface yield, then there is nothing to restrain the wad, and the cylinder is said to codapse. With an ideal material which does not work harden the codapse pressure, P, sometimes caded the full plastic flow pressure, the full overstrain pressure or the full thickness yield pressure, would be the bursting pressure of the cylinder. It is given by equation 10 when thus... 

As two surfaces are brought together, the pressure is extremely large at the initial few points of contact, and deformation immediately occurs to allow more and more to develop. This plastic flow continues until there is a total area of contact such that the local pressure has fallen to a characteristic yield pressure of the softer material. 

Bridgman, P.W. (1952) Studies in Large Plastic Flow and Fracture, with Special Empha.sis on the Effects of Hydrostatic Pressure (McGraw-Hill, New York). 

Fliess-barkeit,/. flowing quality, fluidity fusibility. -bereich, m. plastic range, -betrieb, m. — Fliessarbeit. -druck, m. flow pressure hydraulic pressure, -eigenschaf /. rheologic property. 

Pressure Welding a welding process in which a weld is made by a sufficient pressure to cause plastic flow of the surfaces, which may or may not be heated. 

Other possibility is the application of sonication during the dissolution of electrodeposited metals such as copper or nickel [74]. For both, the texture coefficient of the dissolved plane is affected, and is dependent on the plastic deformation by the shock wave and jet flow pressures. For both metals, the author sees that the greatest effect of ultrasound is located around 20 and 40 kHz. However, there is a marked difference between the two metals. Copper demonstrated the greatest effects at 45 kHz while nickel was most dramatically affected at the lower frequency of 28 kHz, but the possible reasons for that are not provided by the authors. 

Both the indenter and the specimen surfaces should be smooth and homogeneous in order to minimize friction. If the indenter is not smooth, under pressure that is sufficient to cause plastic flow. The specimen will become embossed by the indenter, tending to lock the surfaces. This will induce a large effective friction coefficient. 

The net area of this intimate contact is called the real area of contact Areai. It is assumed that plastic flow occurs at most microscopic points of contact, so that the normal, local pressures correspond to the hardness aj, of the softer of the two materials that are in contact. The (maximum) shear pressure is given by the yield strength cry of the same material. The net load L and the net shear force Fs follow by integrating aj, and cry over the real area of contact Areai. That is, L = cs, Arca and Fs = ayAreai. Hence, the plastic deformation scenario results in the following (static) friction coefficient ... 

In aU wrought processes, the flow of metal is caused by application of an external force or pressure that pushes or pulls a piece of metal or alloy through a metal die. The pressure required to produce plastic flow is determined primarily by the yield stress of the material (cf. Section 5.1.4.3) which, in turn, controls the load capacity of the machinery required to accomplish this desired change in shape. The pressure, P, used to overcome the yield stress and cause plastic deformation is given by... 

Fig. 2.1. Relationship of pressure Pv under indenter and the corresponding initial plastic flow and flow limit aT with uniaxial compression. (After Kelly, 1973)...

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