The analysis of the impact of the method of fastening on strain-stress behavior of composite overwrapped pressure vessel

Currently, composite overwrapped pressure vessels (COPV), with high weight efficiency, are widely used in spacecraft (SC). In satellite construction COPVs provide necessary volume of working fluid for the realization of a highly efficient scheme of raising SC into geostationary orbit using standard electric propulsion engines. The issue of using such vessels in order to increase the period of active lifetime of SC and the implementation of deep-space exploration programs is relevant as well. The urgent task is to ensure the reliability of COPVs. The study of foreign literature suggests that fastening elements in direct contact with the vessel, have an important impact on the strain-stress behavior (SSB) of the vessel. The paper discusses the basic methods of fastening large-sized COPVs having a spherical shape - an adapter module is made in the form of a “skirt” and a cable-stayed system. We have created a finite element model (FEM) of COPV to analyze the effect of fastening elements on SSB of COPV. The analysis of the obtained results of the calculation shows that a cable-stayed system has almost no effect on SSB of COPV, in contrast to a composite “skirt”, which reduces the effective stresses in the place of attachment to the vessel by two times or more, causing uneven distribution of stresses. The composite “skirt” directly transfers its buckling mode to the vessel, which reflects the significant effect of the “skirt” on the vessel’s SSB. The use of a composite “skirt” in comparison with a cable-stayed system has high probability of COPV failure. The obtained results show that a cable-stayed system is more effective way to fasten COPV than a composite “skirt”.