scholarly journals Discussion: “Critical Pressure of Conical Acrylic Windows Under Short-Term Hydrostatic Loading” (Stachiw, J. D., 1967, ASME J. Eng. Ind., 89, pp. 417–425)

1967 ◽  
Vol 89 (3) ◽  
pp. 425-426
Author(s):  
A. B. Rechnitzer
Keyword(s):  
Critical Pressure ◽  
Short Term ◽  
Hydrostatic Loading

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.

Critical Pressure of Conical Acrylic Windows Under Short-Term Hydrostatic Loading

1967 ◽  
Vol 89 (3) ◽  
pp. 417-425
Author(s):  
J. D. Stachiw
Keyword(s):  
Experimental Study ◽  
Critical Pressure ◽  
Short Term ◽  
Included Angle ◽  
Hydrostatic Loading

An experimental study has been conducted to determine the critical pressure of conical acrylic windows under short-term hydrostatic loading. Conical windows with 30, 60, 90, 120, and 150 deg included angle, and thickness-to-diameter ratios in the 0.125 to 1.0 range have been tested to destruction. Both their critical pressures and displacements through the mounting have been recorded and plotted for ready reference of designers.

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.

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.

Flanged Acrylic Plastic Hemispherical Shells for Undersea Systems—Part 2: Static and Cyclic Fatigue Life Under Hydrostatic Loading

1978 ◽  
Vol 100 (2) ◽  
pp. 249-260
Author(s):  
J. D. Stachiw ◽  
R. Sletten
Keyword(s):  
Fatigue Life ◽  
Fatigue Cracks ◽  
Cyclic Fatigue ◽  
Bearing Surface ◽  
Short Term ◽  
Ring Groove ◽  
Working Pressure ◽  
Temperature Range ◽  
Acrylic Plastic ◽  
Hydrostatic Loading

Over 25 acrylic plastic windows with t/Ri = 0.364 in the shape of hemispherical domes with equatorial flanges have been thermoformed from flat sheets and tested under short term, long term, and cyclic pressure loading at 65–75°F ambient temperature. Two kinds of flanges with O-ring grooves on the bearing surfaces were experimented with: Type 1, a flat lip with a rounded heel and instep, and Type II, a conical lip with a rounded heel. The 14,500 psi short term critical pressure of hemispherical windows with t/Ri = 0.364 was found to be independent of the equatorial flange configuration. Both the static and cyclic fatigue lives of the windows were also found to be independent of equatorial flange configuration. In either case, the maximum acceptable working pressure for 65–75°F temperature range was found to be 1000 psi. Only by elimination of the O-ring groove in the bearing surface of the window flange and the use of a thin neoprene bearing gasket between the arylic flange and the steel is it possible to extend the working pressure to 2000 psi for 65–75°F temperature range. Operating the flanged windows at pressures in excess of the safe working pressures shown above will generate fatigue cracks in the bearing surface of the flange in less than 1000 pressure cycles; at 5000 psi pressure the cyclic fatigue life decreases to less than 100 cycles.

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.

scholarly journals EXPERIMENTAL VERIFICATION OF CONSTRUCTIVE SOLUTION OF A NEW TYPE FRAMEWORK

2021 ◽  
Vol 1 (161) ◽  
pp. 38-45
Author(s):  
V.S. Shmukler ◽  
O.I. Lugchenko ◽  
A.H. Nazhem
Keyword(s):  
Experimental Verification ◽  
Test Procedure ◽  
Field Testing ◽  
Building Structures ◽  
Reinforced Concrete Frame ◽  
Short Term ◽  
Concrete Frame ◽  
Hydrostatic Loading ◽  
National University ◽  
Object Of Study

Experimental verification is an integral part of the study for both new designs and new materials and technologies. To assess the features of deformation of the lightweight frame, a series of tests using the method of hydrostatic loading, developed at the Department of Building Structures O.M. Beketov national university of urban economy in Kharkiv. A fragment of a monolithic reinforced concrete frame with a floor slab with a span of 6.0 m and a thickness of 500 mm (thickness of both claddings 100 mm, liner thickness 300 mm) was selected as the object of study. The purpose of the study is to assess the deformability of lightweight frame structures. The tests were implemented under the action of short-term and long-term evenly distributed loads, and were carried out in accordance with the method of hydraulic tests of plates and shells on the basis of the requirements of DSTU B B.2.6-7: 95. For research the research method based on hydrostatic loading of object when loading is set by weight of water is used, and its size is regulated by height of a water column. To carry out the described test procedure on the mezzanine floor of the seventh floor was assembled inventory pool of formwork panels with dimensions in terms of 5.2x2.8 m and a board height of 1.15 m. To register the measured displacements, sensors are supplied to the object under study, which allow to establish the characteristics of the stress-strain state of the object of study. Use of this method, in comparison with other existing, allows to define durability and deformability of various full-scale designs at short-term and long loading without their destruction and a stop of production process. The obtained results of field testing of a fragment of a lightweight frame indicate that the nature of the deformation of the floor under load correlates with the results of similar studies that have been repeatedly conducted for the frames of buildings with load-bearing elements with a continuous cross section.

Conceptual short-term memory (CSTM) supports core claims of Christiansen and Chater

2016 ◽  
Vol 39 ◽  
Author(s):  
Mary C. Potter
Keyword(s):  
Working Memory ◽  
Rapid Serial Visual Presentation ◽  
Language Comprehension ◽  
Short Term Memory ◽  
Visual Presentation ◽  
Long Term Memory ◽  
Short Term ◽  
Term Memory ◽  
Use Of Knowledge

AbstractRapid serial visual presentation (RSVP) of words or pictured scenes provides evidence for a large-capacity conceptual short-term memory (CSTM) that momentarily provides rich associated material from long-term memory, permitting rapid chunking (Potter 1993; 2009; 2012). In perception of scenes as well as language comprehension, we make use of knowledge that briefly exceeds the supposed limits of working memory.

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