Self-Hooping

Application of cold extrusion process to manuf of artillery shells is discussed in Refs 8, 9. 10. 12, 13 14 and its application to manuf of gun-barrels is briefly discussed as the Auto-frettage or Self-hooping in Vol 1, p A510-R of this Encycl... 

Radial Expansion. A method of making gun tubes by expanding steel cylinders under internal pressure until the interior diameter has been permanently enlarged. This method is also known as cold working and auto-frettage (Fr term meaning self-hooping )... 

Self-Hooping. See Autofrettage A510-R Semi-Gelatine (A British Ammonium Nitrate Not-Permitted Dynamite) A368 (table)... 

Multiwall—Begins with a core about ll in. to 2 in. thick. Outer layers about the same thickness are successively shrunk fit over the core. Tliis creates compressive stress in the core, which is relaxed during pressurization. The process of compressing layers is called autofrettage from the French word meaning self-hooping. ... 

Zhang L, Bartels C, Yu Y, Shen H, Eisenberg A. Mesosized crystal-like structure of hexagon-ally packed hollow hoops by solution self-assembly of diblock copolymers. Phys Rev Lett 1997 79 5034-5037. 

FIGURE 7.30. Different morphologies found upon self-assembly of PS-fr-PAA copolymers, (a) micellar spheres (b) micellar rods (c) lamellae (d) vesicles (e) hexagonally packed hollow hoop (HHH) structures (f) LCMs and (g) the internal structure of a LCM. Reproduced with permission from the Canadian Chemical Society. 

Fig. 11.3. A representative synthetic barrel-stave pore self-assembled from four p-octiphenyl monomers (left). Molecular model with p-octiphenyl staves in grey, j -sheet hoops in yellow, external fullerene ligands in gold and an internal a-helix blocker in red (right, adapted from Ref. 4).

Brown MD, Gray AI, Tetley L, Santovena A, Rene J, Schatzlein AG, Uchegbu IF (2003) In vitro and in vivo gene transfer with poly(amino add) vesicles. J Contr Release 93(2) 193-211 Zhang L, Bartels C, Yu Y, Shen H, Eisenbeig A (1997) Mesosized crystal-Uke stmcture of hexagonally packed hollow hoops by solution self-assembly of diblock copolymers. Phys Rev Lett 79 5034-5037... 

The simplest design is a unimolecular ion channel. Nevertheless, designing and synthesizing such macromolecules is complicated, and numerous examples of ion channels rely in the self-assembly of several structures within the membrane to form the functional pore. Depending on the type of molecules macrocycles, staves, or even smaller molecules can form barrel-hoop, barrel staves, or barrel rosette structures (Figure 7). 

Shki ls with Self-supportivi Roofs. A seIf-sup M r(-ing roof is one which is. supported only on its peripfiery, without added structural support. Such roofs cause a compressive stress in the roof plates, wliich i.s transferred to the shell as hoop tension. A stiflfening angle should be ai ded to the top shell course at the junction of the roof and shell to al orb the stress as a tensile load. The forces acting on the ring are shown in Fig, 3.19. 

The autofrettage process, which can be described as a self-shrinking process, provides beneficial compressive hoop stresses at the bore of hollow component, for example, a tube. 

The autofrettage process, which can be described as a self-shrinking process, provides beneficial compressive hoop stresses at the bore of hollow component, for example, a tube, and prolongs their fatigue lifetime, where fatigue life refers to the number of the allowed design cycles by the code or the number of cycles to initiate first cracks. 

Base plate uplifting in those tanks referred to as unanchored or self-anchored, apart from its effect on the base plate connection may lead to an increase of the compressive vertical stress in the shell, which is critical for buckUng-related modes of failure. At the wall side opposite to the uplifted area, vertical compression is maximum and hoop compressive stresses are generated in the shell, due to the membrane action of the base plate. The uplifting parameters of the tank can be seen in (Fig. 10). 

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