Analysis of failure loads and optimal design of composite lattice cylinder under axial compression

Deformation and failure mechanisms of lattice cylindrical shells under axial loading

Analysis of practical experience in the construction and operation of the main fairings of launch vehicles has revealed the currently widely used sandwich structures with composite load-bearing sheathing combined with a cellular filler. The considered structures are characterized by a rather large number of parameters whose variation significantly changes the mass of an article. An approach to optimizing such structures as the main fairing of a launch vehicle in terms of mass has been further developed. The approach includes the essentially improved components of fragments of known analogs, previously developed by a team of authors, as well as the new fragments, which were not taken into consideration before. In contrast to known works, the approach has made it possible to solve the complex multi-parametric task on the optimal design of the considered class of equipment, almost without loss of accuracy. To this end, the optimization process was divided into several stages based on the reasonable levels of parameters’ significance that are included in the objective function ‒ a minimal mass. An analysis of effectiveness of the reinforcement structure for bearing sheaths has been performed, as well as the preliminary optimization of a cellular filler’s properties, which significantly simplified the selection of their optimal parameters. It has been shown that at a minimum gain in mass due to the optimal reinforcement scheme, which is approximately 5 % compared to a quasi-homogeneous sheath, there is an actual risk of a two-fold increase in the mass of a sheath when choosing a substantially non-optimal structure of the sheath. The result of this study is the established rational parameters for a scheme of reinforcement of bearing sheaths and a cellular filler, as well as their geometric parameters, which ensured a reduction in the mass of the main fairing in comparison with the basic variant, by 51 % or 118.2 kg. The results obtained allow further development and improvement, with almost no changes in its concept and structure in the direction of integration of auxiliary structural elements of the head fairing into optimization

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S. Vijayakumar

Papers

Parametric based design of CFRP honeycomb sandwich cylinder for a spacecraft