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Self-shadowing of a spacecraft in the computation of surface forces. An example in planetary geodesy

Balmino G., Marty J. C.

Artificial Satellites : Journal of Planetary Geodesy

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2018

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Vol. 53, No. 1

1--27

EN

We describe in details the algorithms used in modelling the self-shadowing between spacecraft components, which appears when computing the surface forces as precisely as possible and especially when moving parts are involved. This becomes necessary in planetary geodesy inverse problems using more and more precise orbital information to derive fundamental parameters of geophysical interest. Examples are given with two Mars orbiters, which show significant improvement on drag and solar radiation pressure model multiplying factors, a prerequisite for improving in turn the determination of other global models.

2

Exact solution to the structural instability of a parallel array of mutually attracting identical simply-supported plates

Wang X., Liu L.

Archives of Mechanics

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2017

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Vol. 69, nr 3

243--256

EN

By means of the theory of elasticity, we investigate the structural instability of a parallel array of identical simply-supported plates. One plate interacts with the neighboring plates through surface attractive forces. The proposed method is based on the 2 × 2 transfer matrix for a plate and on the solution of the generalized eigenvalue problem for the plate array. Analytical expressions of the critical interaction coefficients for two, three and four interacting plates are obtained when the end-effect of the plates at the ends of the parallel array and the surface energy of the plates are ignored. The influence of the end-effect and surface energy on the critical interaction coefficient is also numerically studied. Our solution is valid whether the plates are thin or extremely thick.

3

Zastosowanie metody ortogonalizacyjnej do zagadnienia stateczności powłoki kulistej obciążonej siłami powierzchniowymi o kierunku równoleżnikowym

Joniak S.

Zeszyty Naukowe Katedry Mechaniki Stosowanej / Politechnika Śląska

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2005

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z. 29

169-174

PL

Rozpatrywany jest problem utraty stateczności powłoki kulistej w zakresie sprężystym. Powłoka jest obciążona rownómiernie rozłożoną silą powierzchniową o kierunku równoleżnikowym. Równaniami problemu są równanie: nierozdzielności i równowagi. Rozwiązuje się je metodą Bubnowa-Galerkina po przyjęciu postaci funkcji sił i funkcji ugięcia; spełniają one warunki brzegowe zagadnienia. Ostatecznie uzyskuje się równanie algebraiczne na bezwymiarowy parametr obciążenia. Z równania tego należy wyznaczyć minimalną wartość tego parametru; jest to wartość krytyczna tego parametru. Praca konczy się przykładem liczbowym.

EN

The shell is loaded by uniformly distributed surface load of a parallel direction. A problem of elastic stability loss of the shell is considered. The problem is solved by the orthogonalization method. Once a stress function is accepted that strictly satisfies some of boundary conditions whereas the other are satisfied with accuracy respected to a constant, the coefficients of the stress functions are determined by the solution of compatibility equation with Bubnov -Galerkin method. Next, a deflection function is accepted after stability loss. This function fulfils the boundary conditions of the problem. Stress function and deflection function are subsequently inserted to equilibrium equation that is solved by Bubnov - Galerkin method. Hence, an algebraic equation for dimensionless parameter is obtained. This equation allows a minimal value of this parameter; this is a critical value of load parameter. A numerical example is included.