shell, stability, defects, bulk material, bending, critical force, sample.

The limit state for bending thin-walled cylindrical shells with initial geometry imperfections has been studied experimentally and theoretically. High-quality samples are made by deep drawing in a matrix from a sheet and from a pipe by turning on a lathe, which have geometric imperfections (thickness, diameter). The material of the samples is aluminum alloys 3004 and D16T. Before testing, the samples were carefully measured and examined for defects. A special stand was made, to which samples were rigidly attached at one end, while the other end was free. A transverse force was applied to the free end in steps until it lost stability. Empty and iron-powder-filled samples were tested. The load and deflection of the free end of the sample were recorded by an ICH-10 clock type indicator. Linear dependences of the deflection on the load were obtained; stability was lost in elasticity. Numerical calculations were performed in the Dynamics-3 software package. Ideal samples were taken for calculations. Comparing the critical loads obtained by experiments and numerical calculations, we judged the effect of initial imperfections on the limit state. The numerically calculated critical force was always greater than the experimental value. Initial imperfections of the samples reduced the critical force from 2.3% to 32.5%. For samples with small dents in the zone of loss of stability, the critical force decreased by 1..2 times. In iron powder-filled samples, the critical force was greater by up to 40.5% than in empty samples.

Mikhail Vasilyevich Petrov, Doctor of Engineering, Professor, Chuvash state University named after I. N. Ulyanov, Cheboksary, Russia.

Ekaterina Grigoryevna Gonik, Senior Lecturer, Chuvash state University named after I. N. Ulyanov, Cheboksary, Russia.

Boris Vasilyevich Mikhailov, Candidate of technical Sciences, Associate Professor, Chuvash state University named after I. N. Ulyanov, Cheboksary, Russia.