Lattice cylindrical shell with a round transverse profile and variable stiffness

Now in the aerospace technology there are three main constructive and technological concepts - supported, sandwich and lattice. Basic feature of the first two concepts is that load is generally perceived by a covering, and edges or filler provide flexural rigidity and resilience to stability loss. In lattice constructions the basic bearing elements are ribs which provide at the same time membrane and flexural rigidity of construction and are made of the unidirectional carbon fiber composite material having high specific rigidity and durability. Composite lattice cylindrical shells are widely applied as load-bearing units of spacecrafts. In use as a part of the spacecraft such shells are exposed to complex influences of static and dynamic loadings. Influence of these loadings leads to emergence of tension differing in different parts of a shell in ribs of lattice structure. The construction considered in this article has additional longitudinal ribs in the areas of coverage of axial loadings. Depending on value of these loadings it is possible to regulate distribution of longitudinal ribs on perimeter, and also their quantity and length. Efficiency of entering into lattice structure of a shell of longitudinal ribs is shown in this article. The task of determination of the first frequency of longitudinal and cross oscillations of a lattice cylindrical shell with spiral and ring ribs and also of a shell with variable rigidness is solved. The analysis of influence of number of pairs of spiral ribs and their angle of unwinding on value of the first oscillation frequency is made. For a shell with variable rigidness influence of these parameters on its level of deforming from action of the lateral bending force is shown, and also assessment of cross stability is made.