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An Investigation of Geometry and Stress for the Mylar Balloon and Tendon Reinforced Inflatables.

紀錄類型:	書目-語言資料,手稿 : Monograph/item
正題名/作者:	An Investigation of Geometry and Stress for the Mylar Balloon and Tendon Reinforced Inflatables./
作者:	Tersigni, Jacob Nemeth.
面頁冊數:	1 online resource (276 pages)
附註:	Source: Masters Abstracts International, Volume: 85-03.
Contained By:	Masters Abstracts International85-03.
標題:	Mechanical engineering. -
電子資源:	click for full text (PQDT)
ISBN:	9798380363266

An Investigation of Geometry and Stress for the Mylar Balloon and Tendon Reinforced Inflatables.
Tersigni, Jacob Nemeth.

An Investigation of Geometry and Stress for the Mylar Balloon and Tendon Reinforced Inflatables. - 1 online resource (276 pages)

Source: Masters Abstracts International, Volume: 85-03.

Thesis (M.S.)--University of Colorado at Boulder, 2023.

Includes bibliographical references

This thesis aims to use experimental and numerical methods to evaluate the geometry and stresses within inflatable structures, and to compare results to analytical models. Because geometry and forces are coupled for inflatable structures, determining both the shape and stresses becomes nontrivial. Specifically, the thesis focuses on the Mylar balloon and tendon reinforced balloons. The particular tendon reinforced balloon variant we examine is the Ultra High Performance Vessel (UHPV), which is constructed by adding tendons to a pair of inflated disks joined at the perimeter. Since the Mylar balloon is also constructed from inflated disks, their behaviour is highly relevant to the study of UHPV balloons.In the first part of the thesis, 3D scanning is used to capture the inflated shape of Mylar balloons as a function of pressure. Using 3D scan data, the shapes of the balloons are compared to analytical models developed for the Mylar balloon. These analytical models rely on two major assumptions: first, that the balloon membrane is inextensionable, and second, that membrane wrinkling leads to an absence of membrane tension in the circumferential direction. Our results show that deformation of the membrane in inflated Mylar balloons causes deviations from the expected shape. These deviations in geometry also correspond to differences between the experimental stress results and those presented in the literature. Strain measurements are also taken on the balloon membrane using microscopic imaging techniques which show that high strains near the balloon poles cause an increase in curvature not predicted by the analytical models. However, the applicability of these strain measurements is limited by a simplified material model which assumes the membrane is isotropic and disregards time-dependent viscoelastic behaviour. A new numerical model is then created which expands on existing models by incorporating membrane extension. Numerical results provide an improvement over current models, but are limited by our material model. The wrinkling behaviour of Mylar balloons is also examined, and the area lost to wrinkling is evaluated using 3D scan data. These results are then compared to the analytical estimates for area loss, which serve as a reasonable estimate when membrane strain is small. Finally, the patterns of wrinkling and clefting in the balloon membrane are examined using a Fourier Transform. Results show that the number of clefts which form in the balloon remains constant at high pressures.The second part of the thesis focuses on the UHPV balloon, for which reinforcing tendons are added to the basic Mylar balloon architecture. These tendons are shorter than the initial arc length of the balloon, and thus lobes are created upon inflation. An analytical model is first developed in order to estimate the geometry of UHPV balloons using simplifying assumptions commonly cited in the literature. Using this model, we evaluate the sensitivity of balloon shape to the number of tendons and the tendon shortening ratio.3D scanning is then used to capture the shape of two UHPV balloons with 16 and 40 tendons respectively. Using the balloon shape, we estimate the tension present in each of the reinforcing tendons, and compare the results to estimates from the literature. Results indicate that, while analytical models provide a reasonable estimate for average tendon tension, they underestimate tendon tension at the equator. The 3D scanning data is also used to evaluate the shape of UHPV lobes. Unlike other tendon reinforced balloon architectures, UHPV lobes do not form arcs with constant curvature. By assuming constant curvature, analytical models underestimate the stress present in the balloon membrane. Furthermore, previous research has shown that small changes in lobe shape have a large influence on the stability of tendon reinforced balloons, which have a propensity to buckle during inflation. Lastly, we examine the distribution of wrinkles in the balloon membrane adjacent to the reinforcing tendons. Results show that because the tendons are free to slide on the balloon surface, the distribution of wrinkles is not uniform and changes with the number of tendons. These results also show that current finite element models for UHPV balloons which assume the tendons are fixed to the membrane do not accurately characterize the wrinkling distribution.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2024

Mode of access: World Wide Web

ISBN: 9798380363266Subjects--Topical Terms:

557493
Mechanical engineering.
Subjects--Index Terms:

BalloonsIndex Terms--Genre/Form:

554714
Electronic books.

An Investigation of Geometry and Stress for the Mylar Balloon and Tendon Reinforced Inflatables.
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520 $a This thesis aims to use experimental and numerical methods to evaluate the geometry and stresses within inflatable structures, and to compare results to analytical models. Because geometry and forces are coupled for inflatable structures, determining both the shape and stresses becomes nontrivial. Specifically, the thesis focuses on the Mylar balloon and tendon reinforced balloons. The particular tendon reinforced balloon variant we examine is the Ultra High Performance Vessel (UHPV), which is constructed by adding tendons to a pair of inflated disks joined at the perimeter. Since the Mylar balloon is also constructed from inflated disks, their behaviour is highly relevant to the study of UHPV balloons.In the first part of the thesis, 3D scanning is used to capture the inflated shape of Mylar balloons as a function of pressure. Using 3D scan data, the shapes of the balloons are compared to analytical models developed for the Mylar balloon. These analytical models rely on two major assumptions: first, that the balloon membrane is inextensionable, and second, that membrane wrinkling leads to an absence of membrane tension in the circumferential direction. Our results show that deformation of the membrane in inflated Mylar balloons causes deviations from the expected shape. These deviations in geometry also correspond to differences between the experimental stress results and those presented in the literature. Strain measurements are also taken on the balloon membrane using microscopic imaging techniques which show that high strains near the balloon poles cause an increase in curvature not predicted by the analytical models. However, the applicability of these strain measurements is limited by a simplified material model which assumes the membrane is isotropic and disregards time-dependent viscoelastic behaviour. A new numerical model is then created which expands on existing models by incorporating membrane extension. Numerical results provide an improvement over current models, but are limited by our material model. The wrinkling behaviour of Mylar balloons is also examined, and the area lost to wrinkling is evaluated using 3D scan data. These results are then compared to the analytical estimates for area loss, which serve as a reasonable estimate when membrane strain is small. Finally, the patterns of wrinkling and clefting in the balloon membrane are examined using a Fourier Transform. Results show that the number of clefts which form in the balloon remains constant at high pressures.The second part of the thesis focuses on the UHPV balloon, for which reinforcing tendons are added to the basic Mylar balloon architecture. These tendons are shorter than the initial arc length of the balloon, and thus lobes are created upon inflation. An analytical model is first developed in order to estimate the geometry of UHPV balloons using simplifying assumptions commonly cited in the literature. Using this model, we evaluate the sensitivity of balloon shape to the number of tendons and the tendon shortening ratio.3D scanning is then used to capture the shape of two UHPV balloons with 16 and 40 tendons respectively. Using the balloon shape, we estimate the tension present in each of the reinforcing tendons, and compare the results to estimates from the literature. Results indicate that, while analytical models provide a reasonable estimate for average tendon tension, they underestimate tendon tension at the equator. The 3D scanning data is also used to evaluate the shape of UHPV lobes. Unlike other tendon reinforced balloon architectures, UHPV lobes do not form arcs with constant curvature. By assuming constant curvature, analytical models underestimate the stress present in the balloon membrane. Furthermore, previous research has shown that small changes in lobe shape have a large influence on the stability of tendon reinforced balloons, which have a propensity to buckle during inflation. Lastly, we examine the distribution of wrinkles in the balloon membrane adjacent to the reinforcing tendons. Results show that because the tendons are free to slide on the balloon surface, the distribution of wrinkles is not uniform and changes with the number of tendons. These results also show that current finite element models for UHPV balloons which assume the tendons are fixed to the membrane do not accurately characterize the wrinkling distribution.
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