Spherical Acrylic Plastic Hulls Under External Explosive Loading

1977 ◽  
Vol 99 (2) ◽  
pp. 469-479
Author(s):  
J. D. Stachiw
Keyword(s):  
Internal Surface ◽  
Explosive Loading ◽  
Impulse Loading ◽  
Underwater Explosions ◽  
Acrylic Plastic ◽  
Explosive Charges ◽  
Sufficient Magnitude ◽  
Peak Pressures

NEMO-type acrylic spherical hulls have been subjected to underwater explosions in order to determine their resistance to hydrodynamic impulse loading. Six 15-in. OD and one 66-in. OD spheres have been subjected to explosions of sufficient magnitude to initiate fracture in the hull. The tests were conducted at simulated depths of 10, 100, 1000, and 2000 ft utilizing explosive charges of 1.1, 8.2, 14.6, 169.9, 387.8, and 688.6 grams. The tests have shown that an acrylic sphere will fracture in 0–50 ft depths range under dynamic peak pressures that are smaller in magnitude than static pressures required for general implosion of the sphere. At depth that is equal to 0.2 of static implosion pressure, the magnitude of dynamic peak pressures must be in excess of the static implosion pressure before fracture of the acrylic sphere is initiated. Fractures were generally initiated on the internal surface of the sphere at two locations: (a) at a point closest to the explosive and (b) at a point most remote from the explosive. The fractures were generally in the shape of a star.

Shock Resilience of Structural Pillars in Naval Vessels

2017 ◽  
Vol Vol 159 (A1) ◽  
Author(s):  
J C Rigby ◽  
C Moss ◽  
G Thomas
Keyword(s):  
Impulse Loading ◽  
Structural Members ◽  
Open Spaces ◽  
Underwater Explosions

Although structural pillars are extensively used in commercial vessels, traditionally their use on board UK warships has been discouraged. This is due to the tendency of pillars to “punch through” the deck when subjected to the high impulse loading of shock from underwater explosions (UNDEX). There are however many spaces within naval ships that would significantly benefit from the wide-open spaces created from the use of pillars as opposed to full bulkheads, such as machinery rooms, mooring decks and accommodation flats. This paper re-addresses the question of a shock capable pillar, looking at how a pillar can be designed or mounted to increase its resilience to shock from underwater explosions. It is proposed that the advice against the use of pillars in warships could be unfounded; this is supported by the fact that not all navies reject their use. The results of this study imply that as long as the pillar is sited properly on primary structural members, then pillar buckling should occur long before “punch though”.

Deformation and fracture produced in thick cylinders by impulse loading

1970 ◽  
Vol 5 (4) ◽  
pp. 249-254
Author(s):  
J E Cousins
Keyword(s):  
Mild Steel ◽  
Circumferential Strain ◽  
Explosive Loading ◽  
Impulse Loading ◽  
Deformation And Fracture ◽  
Internal Explosive Loading ◽  
Increasing Load

The deformation and fractures produced by internal explosive loading in thick cylinders are different to those caused by a gradually increasing load. Graphs showing the variation in circumferential strain for cylinders of different lengths and diameters are presented and the fractures discussed. The similarity between the fracturing of perspex and mild-steel cylinders is also shown.

SHOCK RESILIENCE OF STRUCTURAL PILLARS IN NAVAL VESSELS

2021 ◽  
Vol 159 (A1) ◽  
Author(s):  
J C Rigby ◽  
C Moss ◽  
G Thomas
Keyword(s):  
Impulse Loading ◽  
Structural Members ◽  
Open Spaces ◽  
Underwater Explosions

Although structural pillars are extensively used in commercial vessels, traditionally their use on board UK warships has been discouraged. This is due to the tendency of pillars to “punch through” the deck when subjected to the high impulse loading of shock from underwater explosions (UNDEX). There are however many spaces within naval ships that would significantly benefit from the wide-open spaces created from the use of pillars as opposed to full bulkheads, such as machinery rooms, mooring decks and accommodation flats. This paper re-addresses the question of a shock capable pillar, looking at how a pillar can be designed or mounted to increase its resilience to shock from underwater explosions. It is proposed that the advice against the use of pillars in warships could be unfounded; this is supported by the fact that not all navies reject their use. The results of this study imply that as long as the pillar is sited properly on primary structural members, then pillar buckling should occur long before “punch though”.

What catalysis needs from the electron microscopist

1988 ◽  
Vol 46 ◽  
pp. 694-695
Author(s):  
Alexis T. Bell
Keyword(s):  
Active Sites ◽  
Heterogeneous Catalysts ◽  
Catalyst Deactivation ◽  
Surface Composition ◽  
Internal Surface ◽  
Active Phase ◽  
Atomic Scale ◽  
Metal Catalyst ◽  
Internal Surface Area ◽  
Porous Support

Heterogeneous catalysts, used in industry for the production of fuels and chemicals, are microporous solids characterized by a high internal surface area. The catalyticly active sites may occur at the surface of the bulk solid or of small crystallites deposited on a porous support. An example of the former case would be a zeolite, and of the latter, a supported metal catalyst. Since the activity and selectivity of a catalyst are known to be a function of surface composition and structure, it is highly desirable to characterize catalyst surfaces with atomic scale resolution. Where the active phase is dispersed on a support, it is also important to know the dispersion of the deposited phase, as well as its structural and compositional uniformity, the latter characteristics being particularly important in the case of multicomponent catalysts. Knowledge of the pore size and shape is also important, since these can influence the transport of reactants and products through a catalyst and the dynamics of catalyst deactivation.

The distribution and density of ciliary tufts on the siphons of Anodonta cygnea (Mollusca: Bivalvia)

1990 ◽  
Vol 48 (3) ◽  
pp. 518-519
Author(s):  
Wen-lung Wu
Keyword(s):  
Osmium Tetroxide ◽  
Internal Surface ◽  
Mechanical Stimuli ◽  
Type Ii ◽  
Sensory Receptors ◽  
Anodonta Cygnea ◽  
Type Iv ◽  
Sem Study ◽  
Inhalant Siphon ◽  
Type V

The mantle of bivalves has come entirely to enclose the laterally compressed body and the mantle margin has assumed a variety of functions, one of the pricipal ones being sensory. Ciliary tufts, which are probably sensory, have been reported from the mantle and siphons of several bivalves1∽4. Certain regions of the mantle margin are likely to be more or less, sensitive to certain stimuli than others. The inhalant siphon is likely to be particularly sensitive to both chemical and mechanical stimuli, whereas the exhalant siphon will be less sensitive to both. The distribution and density of putative sensory receptors on the in-and ex-halant siphon is compared in this paper.The excised siphons were fixed in glutaraldehyde and osmium tetroxide, the whole procedure of SEM study is recorded in Wu's thesis.Type II cilia cover the tips of tentacles, 6.13um. Type IV and type V cilia are found on the surface of tentacles. Type IV cilia are occasionally present at the tips of tentacles, 8 um long. They are the commonest type on the surface of tentacles. Type VI cilia occor in the internal surface of the inhalant siphon, but are not found on the surface of tentacles, 6.7-10um long.

Internal surface finishing

2018 ◽  
Author(s):  
JIANG GUO
Keyword(s):  
Internal Surface ◽  
Surface Finishing

This entry introduces five kinds of established internal surface finishing technologies.

Physical and Optical Properties of The Films Ð’i2Te3-Bi2Se3

2015 ◽  
Vol 11 (2) ◽  
pp. 3017-3022
Author(s):  
Gurban Akhmedov
Keyword(s):  
Thin Film ◽  
Optical Properties ◽  
Surface Temperature ◽  
Thermal Evaporation ◽  
Low Voltage ◽  
Internal Surface ◽  
Differential Resistance ◽  
Work Cycle

Results of researches show, that film p-n the structures received by a method of discrete thermal evaporation in a uniform work cycle, are suitable for use in low-voltage devices.  As a result of work are received p-n heterojunctions in thin-film execution, described by high values of differential resistance. Show that, thermo endurance - T0 maybe using as characteristic of thermo endurance of optic materials. If heating flow, destruction temperature and internal surface temperature is measured during test, it is possible to determine value T0 and other necessity characteristics. As a result of the taking test was lead to comparison evaluation of considered materials. Working range of heating flow and up level heating embark have been determined.

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