Prediction of the service life of deep-sea conical acrylic portholes at designing

Burdun, Yevgen; Kochanov, Vladimir; Yuresko, Tetyana

doi:10.15587/1729-4061.2020.194584

Cited by 3 publications

(7 citation statements)

References 5 publications

(7 reference statements)

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“…This phenomenon was also observed during full-scale tests of the porthole. These results confirmed the conclusions of [12,25,31].…”

Section: Experimental Research and Discussion Of Resultssupporting

confidence: 92%

“…Equivalent stresses acquire minimum values when the tapering angle is in the range of 75-105° (when the relative thickness increases, the optimal tapering angle becomes smaller). These results confirmed the conclusions of [27,31], obtained with the use of a series of finite-element calculations. After hydrostatic loading, we also observed plastic wrinkling of the material with the formation of "silver" cracks in the area of the edge of the low-pressure surface (Figure 9) of full-sized translucent elements.…”

Section: Experimental Research and Discussion Of Resultssupporting

confidence: 89%

“…Equivalent stresses acquire minimum values when the tapering angle is in the range of 75-105° (when the relative thickness increases, the optimal tapering angle becomes smaller). These results confirmed the conclusions of [27,31], obtained with the use of a series of finite-element calculations. Analysis of the influence of porthole geometric characteristics on the stress-strain behaviour showed that increase in the tapering angle at the constant relative thickness of the translucent element reduced its axial displacement in all cases.…”

Section: Experimental Research and Discussion Of Resultssupporting

confidence: 89%

“…The experiments and numerical calculations of the stress-strain behaviour of PMMA portholes at different levels of hydrostatic pressure to develop a method of optimal designing regarding operating conditions are described in [31]. Experimental dependences of displacements of portholes made of PMMA at long-term and cyclic impacts of hydrostatic pressure are obtained.…”

Section: Introductionmentioning

confidence: 99%

“…These difficulties, together with the limited choice of fundamental functions from the full range of solutions for the axisymmetric problem of the elasticity theory, do not allow the boundary conditions of the translucent element to be fully met, while the most stress points are always on the surface of the deformable body. However, based on these methods it is possible to obtain relatively simple but fairly accurate applied solutions to the problems [31,34].…”

Section: Introductionmentioning

confidence: 99%

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Influence of Geometric Parameters of Conical Acrylic Portholes on Their Stress–Strain Behaviour

et al. 2022

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Translucent elements in the form of truncated cones, which are made of organic glass, are widely used in the structures of portholes, submersible vessels, space vehicles, pressure chambers, teleboxes and other types of technical equipment. The decisive factor in designing portholes is to ensure the strength of their translucent elements. In order to reduce the weight of portholes and, accordingly, to increase the payload, it is necessary to optimise the geometric parameters of the translucent elements, which include the tapering angle and the ratio of thickness to radius of the smaller base. The paper deals with development of the applied (engineering) method for determining the stress–strain behaviour of the conical translucent elements of portholes made of organic glass under the action of a uniform hydrostatic pressure. Finite-element modelling of the translucent element of the conical porthole is performed, with the calculation of its stress–strain behaviour. External hydrostatic pressure of 10 MPa, absence of loads from the inside and continuous sliding of the translucent element with friction along the conical supporting surface of the porthole metal body are the boundary conditions for the computational model. Full-scale tests of translucent elements of portholes made of organic glass were performed under the action of uniform hydrostatic pressure. Analysis of the influence of geometric characteristics of the portholes on stress–strain behaviour showed that the increase in the tapering angle at the constant relative thickness of the translucent element reduced its axial displacement in all cases. Equivalent stresses acquire minimum values when the tapering angle is in the range from 75° to 105° (when the relative thickness increases, the optimal tapering angle becomes smaller). It is shown that the developed method for determination of the stress–strain behaviour of the conical translucent elements of portholes made of organic glass reflects the real picture of deformation and agrees with the results of full-scale tests. Results of the work allow us to choose the rational parameters of the translucent element for increasing the reliability of portholes through the creation of an effective distribution of stresses and strains in the translucent element, and improving its optical characteristics due to a relatively small deflection in operation.

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“…This phenomenon was also observed during full-scale tests of the porthole. These results confirmed the conclusions of [12,25,31].…”

Section: Experimental Research and Discussion Of Resultssupporting

confidence: 92%

Section: Experimental Research and Discussion Of Resultssupporting

confidence: 89%

“…Equivalent stresses acquire minimum values when the tapering angle is in the range of 75-105° (when the relative thickness increases, the optimal tapering angle becomes smaller). These results confirmed the conclusions of [27,31], obtained with the use of a series of finite-element calculations. Analysis of the influence of porthole geometric characteristics on the stress-strain behaviour showed that increase in the tapering angle at the constant relative thickness of the translucent element reduced its axial displacement in all cases.…”

Section: Experimental Research and Discussion Of Resultssupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Influence of Geometric Parameters of Conical Acrylic Portholes on Their Stress–Strain Behaviour

et al. 2022

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Durability of Acrylic Products during Heat Aging

Kondratiev

Kochanov

Yuresko

et al. 2022

SSP

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Currently, the areas of application of polymethyl methacrylate plastic (acrylic) owing to its unique properties (most notably, lightness, plasticity, exceptional transparency and high impact resistance) range widely from modeling, lighting technology and medicine, automotive industry and watchmaking to aviation, shipbuilding, rocket engineering and production of military equipment. Mechanical characteristics of polymethyl methacrylate plastic, like most polymers, change significantly over time when exposed to temperature. The temperature impact extends to all volume of the material and leads to its “heat aging”, which should be considered when designing the products made of polymethyl methacrylate plastic. The process of thermal destruction is long enough, so it is reasonable to predict the changes in the properties of polymethyl methacrylate plastic using accelerated methods of material specimen aging with subsequent testing under simple loading. The paper deals with the experimental study of the process of changing of physical and mechanical characteristics of polymethyl methacrylate plastic during thermal destruction. Heat aging of the material is identified with the process of the thermal oxidative destruction occurring at a constant rate and specified temperature. It is assumed that the change in polymer’s mechanical properties is proportional to the change in number of its functional groups. The tests were performed on cylindrical specimens with fillets at the ends at three levels of temperature: 40, 70 and 100°C. Specimens were held at each temperature for 2; 5; 10; 20 and 30 days. According to results of statistical processing of experiments, we obtained the average values of ultimate strains for each temperature-time regime. The obtained ultimate strain values were the basis for the construction of long-term aging curves. For the minimum allowable value of ultimate strain in operation, the period of operation of polymethyl methacrylate plastic was determined for different aging temperatures. At the operating temperature of 20oС the period of operation was 12 years. During this period, the ultimate deformability of polymethyl methacrylate plastic decreases to 3%, which is approximately equal to elastic deformations. The results will allow us to predict the period of operation of polymethyl methacrylate plastic products for different values of the ultimate strain and operating temperature.

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Evolving Methods for Design by Analysis for Glassy Polymers in Marine Applications

Kemper¹,

Stromer

2023

Day 3 Wed, May 03, 2023

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The use of glassy polymers such as acrylics and polycarbonate for marine hulls, windows, and transparent housings has been in more demand due to increasing use of ROVs, AUVs, and smaller non-military submarines. New "Design By Analysis" (DBA) methods will provide for innovative applications while maintaining safety, reliability, and traceability. The new approach will account for the type of application while enabling new materials and shapes through a combination of experimental and computational methods based on Verification, Validation, and Uncertainty Quantification (VVUQ). Previous standards for life-critical applications like diving systems and submarines were locked into 1970's empirical methods based on defined shapes without directly using material properties. Other uses of glassy polymers, like camera housings, have been more ad-hoc. The method under development will give equipment designers the option to use modern methods like Finite Element Analysis and Computational Fluid Dynamics to innovate within existing engineering code processes. American Society of Mechanical Engineers (ASME) Pressure Vessels for Human Occupancy (PVHO) codes and standards was developed in the 1960's and 1970's based on US Navy-funded experiments. It has a proven safety record, so much so it was recently incorporated into the ASME Boiler and Pressure Vessel Code for industrial equipment. Limited by its empirical basis, it does not use material properties directly to allow you to reduce the thickness by increasing the strength, as one example. Another limitation is the tables in the code are limited to a specific range of shapes and geometric parameters, all of which were set over 50 years ago without any provision to add new shapes or parameters. These limitations have constrained later equipment development, particularly where there are requirements for engineering code compliance. The proposed DBA method under development through ASME uses PVHO applications as the benchmark for the most extreme risk, given the issue of having humans in a confined space under pressure. Once established, this method can be used for other applications ranging from spaceflight to autonomous vehicles to architectural use with the design margins adjusted based on risk analysis, all with traceability provisions for design, materials, manufacturing, and testing. The techniques proposed for this DBA method are proven and can be used immediately by equipment designers regardless of being part of an ANSI-approved engineering standard.

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Prediction of the service life of deep-sea conical acrylic portholes at designing

Cited by 3 publications

References 5 publications

Influence of Geometric Parameters of Conical Acrylic Portholes on Their Stress–Strain Behaviour

Influence of Geometric Parameters of Conical Acrylic Portholes on Their Stress–Strain Behaviour

Durability of Acrylic Products during Heat Aging

Evolving Methods for Design by Analysis for Glassy Polymers in Marine Applications

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