Inflation and Packaging Simulation of IMOD with The Implicit Non Linear Code SAMCEF
Cruccas, C¹; Bruyneel, M²; Granville, D²; Jetteur, P²; Nebiolo, M³; Palmieri, P³; Augello, G³; Manfredi, L³; Stephane, L^4
1Samtech Italia; ²Samtech s.a.; ³Thales Alenia Space Italia; ⁴ESA/ESTEC

Over the last years, several improvements have been made in SAMCEF Mecano, a general implicit non-linear software developed by Samtech, for providing an industrial solution for the analysis of inflatable and membrane structures. Most of the developments have been carried out under an ESTEC contract, in the frame of PASTISS project – Professional Analysis Software Tool for Inflatable Space Structure [1,2].

SAMCEF has been recently used during the Phase 2 of the Inflatable Module (IMOD) program, SAMTECH being a partner of Thales Alenia Space Italia (TAS-I).

This paper describes this study and provides the details of the solutions obtained with a non linear implicit code (and not an explicit one). The analyses carried out by SAMTECH have been the simulation of the packaging and the inflation process of the IMOD.

For the packaging process of the structure, a refined modelling was necessary in order to consider the real folded and wrinkled deformations. A new shell element formulation without rotational degrees of freedom [1,2] and other SAMCEF modelling capabilities (cyclic symmetry, multi-layered element, etc) have been adopted in order to save computational time. An important issue was the law of adopted material. The comparison between simple linear elastic and non-linear elastic materials with low compression stiffness has shown big differences between the results. This confirms that these kinds of structures are very sensitive to the material law definition, which should be accurate, as much as possible.
The simulation of the entire process has been defined as a whole transient characterised by several phases in order to take into account residual effects between each phase and the next one. The phases are the radial and lateral folding phases, the tie up and release of circumferential belts, and finally the inflation. The simulation achievements are described and documented by dedicated movies and pictures.

[1] Jetteur Ph. and Bruyneel M. (2008). "Advanced capabilities for the simulation of membrane and inflatable space structures using SAMCEF", Recent Advances in Textile Membranes and Inflatable Structures, (Oñate E., Kröplin B., eds.), Springer-Verlag. To appear.

[2] Jetteur Ph. Bruyneel M., Cugnon F. and Granville D. (2006). "Professional Analysis Software Tool for Inflatable Space Structures", Third European Workshop on Inflatable Space Structures, October 10-12, ESA/ESTEC, Noordwijk, The Netherlands, 2006.