Bending of a thin sheet into a circular cylinder with two free edges for the moon conditions

Thin-walled shell structures are widely used in various branches of the machinery industry. The durability and reliability of chemical engineering machines, pipelines, and elements of aircrafts, ships, and other types of shell structures considerably depend on the accuracy in determining their stress–strain behavior. The thin-walled metal products in the form of developable surfaces are usually manufactured by a parabolic bending of a thin flat preform into the desired product, and the bending is conducted without occurring of tears and folds and that is very important if it is made on the moon surface. Parabolic bending takes place with the conservation of rectilinear generators of developable middle surface, and shell thickness remains constant. But in real shell structures due to the Poisson’s ratio, inner bending moments appear in two directions, so the rectilinear generators of developable middle surface will be bent. This situation can be corrected if to make boundary bending moments at both opposite edges not coinciding with the rectilinear generators. The process of parabolic bending of a thin plane slab or a shell with the middle developable surface provokes the appearance of internal normal stresses which can mount to yield strength. The results of the research can be used in marine design, civil engineering, air-space industry, and other manufacturing processes. © 2020, Univelt Inc. All rights reserved.