shell, stability, experiment, calculation, technique, bulk material, torque.

In this work, an experimental study of the stability of cylindrical shells filled with granular material - iron powder, during torsion, was carried out and a method for the operational approximate calculation of the critical torque was developed. Experiments have shown that the stability of shells is lost in elasticity. Linear dependences of the angle of rotation of the cross sections on the torque are constructed, except for shells filled with bulk material at the initial moment of motion. Here, a nonlinear dependence of the angle of rotation of the shell sections on the torque is obtained due to the action of the torque on the friction forces between the powder and the inner wall of the sample. The dependence of the angle of rotation on the torque in both cases is parallel, but for the filled samples, the dependence was shifted by the amount of torque on the friction forces. To verify the correctness of the statement about the effect of friction force on the critical torque, experiments were performed with coating the inner wall of the samples with a lubricant. In this case, the critical torque for samples filled with bulk material coincided with the critical torque for empty samples. To calculate the torque from friction forces, the method for calculating the pressure force of a granular medium on the sample wall was used, which was multiplied by the friction coefficient and the radius of the middle surface of the sample.

The critical torque of the samples filled with iron powder was determined by the sum of the critical torque for empty samples calculated according to the Volmir formula with a torque from friction forces.

The critical torques obtained by calculation were compared with experimental values. Satisfactory convergence within 16% was obtained. The calculation method is recommended for the operational calculation of the critical torque, for shells filled with bulk material, during torsion.

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

Alexander Ivanovich Kibets, Doctor of Physics and Mathematics, Professor, Chief Researcher, Research Institute of Mechanics, N.I. Lobachevsky State University of Nizhny Novgorod, Nizhny

Novgorod, Russia,

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

Ekaterina Grigoryevna Gonik, Ass. Professor, Chuvash state University named after I. N. Ulyanov, Cheboksary, Russia,

Viktor Anatolyevich Ivanov, Senior Lecturer, Chuvash state University named after I. N. Ulyanov, Cheboksary, Russia.