منابع مشابه
Cosmic balloons.
Cosmic balloons, consisting of relativistic particles trapped inside a spherical domain wall, may be created in the early universe. We calculate the balloon mass M as a function of the radius R and the energy density profile, ρ(r), including the effects of gravity. At the maximum balloon mass 2GM/R ≈ 0.52 for any value of the mass density of the wall. [email protected] Domain walls may fo...
متن کاملStability of Lobed Balloons
This paper presents a computational study of the stability of simple lobed balloon structures. Two approaches are presented, one based on a wrinkled material model and one based on a variable Poisson’s ratio model that eliminates compressive stresses iteratively. The first approach is used to investigate the stability of both a single isotensoid and a stack of four isotensoids, for perturbation...
متن کاملShape Optimization of “Pumpkin” Balloons
This paper is concerned with the optimization of the cutting pattern for the lobes of pumpkin-shaped balloon structures. Pumpkin balloons, currently developed for the NASA Ultra-Long Duration Balloon (ULDB), consist of stiff meridional tendons that constrain a thin plastic film. The present study shows that the maximum stability of pumpkin balloons is reached if their surface area is minimized ...
متن کاملMaximally stable lobed balloons
Article history: Received 25 March 2009 Received in revised form 23 September 2009 Available online 23 February 2010
متن کاملViscoelastic behaviour of pumpkin balloons
The lobes of the NASA ULDB pumpkin-shaped super-pressure balloons are made of a thin polymeric film that shows considerable time-dependent behaviour. A nonlinear viscoelastic model based on experimental measurements has been recently established for this film. This paper presents a simulation of the viscoelastic behaviour of ULDB balloons with the finite element software ABAQUS. First, the stan...
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ژورنال
عنوان ژورنال: The Permanente Journal
سال: 2018
ISSN: 1552-5775
DOI: 10.7812/tpp/18-024