scholarly journals Discussion: “Critical Pressure of Spherical Shell Acrylic Windows Under Short-Term Pressure Loading” (Stachiw, J. D., 1969, ASME J. Eng. Ind., 91, pp. 573–584)

1969 ◽  
Vol 91 (3) ◽  
pp. 584-584
Author(s):  
Kiyoshi Tsuji
Keyword(s):  
Spherical Shell ◽  
Critical Pressure ◽  
Pressure Loading ◽  
Short Term

Critical Pressure of Spherical Shell Acrylic Windows Under Short-Term Pressure Loading

1969 ◽  
Vol 91 (3) ◽  
pp. 573-584
Author(s):  
J. D. Stachiw
Keyword(s):  
Spherical Shell ◽  
Atmospheric Pressure ◽  
Convex Surface ◽  
Low Pressure ◽  
Full Scale ◽  
Pressure Loading ◽  
Short Term ◽  
Model Scale ◽  
Hydrostatic Loading ◽  
Sector Angle

Model and full scale acrylic windows in the form of spherical shell lenses with parallel convex and concave surfaces have been imploded by loading their convex surface hydro-statically at 650 psi/min rate while their concave surface was exposed to atmospheric pressure. The thickness of the model scale windows varied from 0.250 to 1.200 in. and of the full scale windows from 0.564 to 4.000 in., while the included spherical sector angle of the lens varied from 30 to 180 degrees in thirty degree increments. The low pressure face diameters of the model scale windows varied from 1.423 to 5.500 in., while those of the full scale windows varied from 6.200 to 35.868 in. In addition to critical pressures, displacement of the lens under hydrostatic pressure has been recorded and plotted as functions of pressure. The critical pressures of spherical acrylic windows have been found to be consistently higher than those of conical or flat disc acrylic windows of same thickness and low pressure face diameter subjected to short-term hydrostatic loading.

Spherical Shell Sector Acrylic Plastic Windows with 12,000 ft Operational Depth for Submersible Alvin

1976 ◽  
Vol 98 (2) ◽  
pp. 523-536 ◽  
Author(s):  
J. D. Stachiw ◽  
R. Sletten
Keyword(s):  
Stress Distribution ◽  
Spherical Shell ◽  
Critical Pressure ◽  
Catastrophic Failure ◽  
Ocean Bottom ◽  
Uniform Stress ◽  
Short Term ◽  
Single Pass ◽  
Sustained Loading ◽  
The Cost

It has been found that the 90-deg plane conical frustum windows with t/Di = 0.7 ratio in ALVIN submersible can be replaced with 90-deg t/Di = 1 spherical shell sector windows without any modification of window seat flanges. The 90-deg spherical shell sector windows with t/Di = 1.0 possess not only a higher short term critical pressure but also develop more uniform stress distribution during a typical dive to 12,000 ft than the t/Di = 0.7 acrylic conical frustum windows that they replace. The 90-deg t/Di = 1.0 spherical shell sector windows (1) withstood, without catastrophic failure, 100 hr sustained loading to 20,000 psi, (2) 33 pressure cycles of 7-hr duration to 13,500 ft depth without any signs of fatigue, and (3) experienced less than 15,000 μin. strain during a simulated typical prooftest dive to 13,500 ft depth. The 90-deg t/Di = 1 spherical shell sector window presents a 50 percent larger view in water than a 90-deg t/Di = 0.7 conical frustum window that it replaces. This permits the observer inside the submersible to cover visually more ocean bottom during a single pass along the bottom and thus decreases the cost of a typical bottom search mission for a submersible.

Flanged Acrylic Plastic Hemispherical Shells for Undersea Application

1975 ◽  
Vol 97 (1) ◽  
pp. 1-9 ◽  
Author(s):  
J. D. Stachiw ◽  
J. R. Maison
Keyword(s):  
Finite Element ◽  
Hydrostatic Pressure ◽  
Stress Distribution ◽  
Boundary Conditions ◽  
Critical Pressure ◽  
Convex Surface ◽  
Elastic Analysis ◽  
Short Term ◽  
Acrylic Plastic ◽  
Hemispherical Shells

The effects of an equatorial flange and a nonuniform wall thickness upon the critical pressure and stress distribution in acrylic plastic hemispheres have been investigated by experimental and analytical methods. Forty acrylic hemispheres were fabricated and tested to destruction under short term hydrostatic pressure applied on the convex surface. Dome apex displacements were obtained from each specimen and strains were obtained from a selected few. A finite element elastic analysis was performed on one window configuration for two different boundary conditions and the experimentally derived stresses were used to determine which boundary conditions was the best for analytical analysis.

Nonlinear Stability Analysis of the Vaulted Roofs With Corrosion Defects of Oil Storage Tank

2009 ◽  
Author(s):  
Baosheng Dong ◽  
Xinwei Zhao ◽  
Hongda Chen ◽  
Jinheng Luo ◽  
Zhixin Chen ◽  
...  
Keyword(s):  
Spherical Shell ◽  
Nonlinear Stability ◽  
Storage Tank ◽  
Critical Pressure ◽  
External Pressure ◽  
Shallow Spherical Shell ◽  
Nonlinear Stability Analysis ◽  
Spherical Shells ◽  
Oil Storage ◽  
Oil Storage Tank

The vaulted roofs of oil storage tank are usually designed as the shallow spherical shells subjecting to a uniform external pressure, which have been widely observed that these shallow spherical shells undergo various levels of corrosion in their employing conditions. It is important to assess the stability of these local weaken shallow spherical roofs due to corrosion for preventing them from occurring unexpected buckling failure. In this paper, the uniform eroded part of a shallow spherical oil tank vaulted roof is simplified as a shallow spherical shell with elastic supports. Based on the simplification, a general pathway to calculate the critical pressure of eroded shallow spherical shell is proposed. The modified iteration method considering large deflection of the shell is applied to solve the problem of nonlinear stability of the shallow spherical shells, and then the second-order approximate analytical solution is obtained. The critical pressure calculated by this method is consistent with the classical numerical results and nonlinear finite element method, and the calculation errors are less than 10%. It shows that it is feasible to apply the method proposed here.

Effect of Temperature and Flange Support on Critical Pressure of Conical Acrylic Windows Under Short Term Pressure Loading

1972 ◽  
Vol 94 (4) ◽  
pp. 853-861
Author(s):  
J. D. Stachiw
Keyword(s):  
Critical Pressure ◽  
Effect Of Temperature ◽  
Short Term ◽  
Ambient Temperatures ◽  
Seating Arrangement ◽  
Hydrostatic Loading ◽  
Percent Increase ◽  
Standard Of Comparison ◽  
The Relationship ◽  
Percent Decrease

Temperature and the seating arrangement in the flange have a significant effect on the critical pressure of conical acrylic windows. Over 400 acrylic windows with 90 deg conical angle were used in this study to establish experimentally the relationship between thickness to minor diameter ratio (t/D), temperature, seating arrangement in the flange, and critical pressure under short term hydrostatic loading. The data indicates that utilizing 70 deg F as standard of comparison, there is, approximately 20 percent increase in critical short term pressure when 32 deg F, and 20 percent decrease when 90 deg F ambient temperatures are utilized, respectively. It was also found that the short term critical pressure of some conical acrylic windows is influenced by the seating arrangement in the flange. As a rule, an increase in the ratio of minor window diameter to minor flange opening diameter (D/Df) raised the short term critical pressure of windows with t/D ≥ 0.375 significantly. For windows with t/D < 0.375, it did not raise the critical pressure.

Lower critical pressure for dynamic stability of a spherical shell

1971 ◽  
Vol 23 (1) ◽  
pp. 337-367
Author(s):  
A. I. Zagustin ◽  
E. A. Zagustin
Keyword(s):  
Spherical Shell ◽  
Dynamic Stability ◽  
Critical Pressure

Spherical Sector Windows With Restrained Edge for Undersea Applications

1977 ◽  
Vol 99 (2) ◽  
pp. 459-468
Author(s):  
J. D. Stachiw
Keyword(s):  
Spherical Shell ◽  
Experimental Evaluation ◽  
Cyclic Fatigue ◽  
Bearing Surface ◽  
Short Term ◽  
Cyclic Pressure ◽  
Fatigue Data ◽  
Vertical Bearing ◽  
Radial Thrust

A new concept for the mounting of spherical sector windows has been experimentally evaluated under short-term, long-term, and cyclic pressure loadings. The new mounting concept requires that the spherical sector windows be provided with square edges instead of conical edges. The horizontal bearing surface of the square edge carries the axial and the vertical bearing surface the radial thrust of the spherical sector window. Experimental evaluation of the new mounting concept has shown that the spherical windows with square edges are subjected to larger flexure moments than similar windows with conical edges. However, the short-term critical pressures of spherical sector windows with square edges and included angle 75 deg &lt; α &lt; 180 deg were found to be only 10 percent less than those of similar windows with conical edges. For spherical sectors with α &lt; 75 deg the square edge mounting provides significantly higher short-term implosion pressures than conical edge mountings. Based on the short-term critical pressures, strains, stresses, and cyclic fatigue data generated by this study, the spherical shell sector windows with square edge mounting are considered acceptable for service in manned submersibles, habitats, or diving bells.

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