Nikolai Chetaev

Born Nov. 23 (Dec. 6), 1902, in the village of Karaduli, in what is now Laishevo Raion, Tatar ASSR; died Oct. 17, 1959, in Moscow. Soviet scientist; specialist in mechanics. Corresponding member of the Academy of Sciences of the USSR (1943).

Chetaev graduated from the University of Kazan in 1924. In 1929, after completing his graduate study, he was sent to Göttingen for advanced study. From 1930 to 1940 he was a professor at the University of Kazan, where he established a school of specialists in theory of the stability of motion. From 1940 he worked at the Institute of Mechanics of the Academy of Sciences of the USSR and was a professor at Moscow State University.

In 1934, Chetaev established the general theorem of the instability of motion, and in 1938 he further developed Lagrange’s theorem of dynamic equilibrium; in 1949 he proposed methods for solving problems of the stability of unsteady motion. He also found the sufficient conditions for the stability of rotary motion of artillery shells. A number of his works were devoted to analytical dynamics. He extended the principle of least constraint to the case of a nonholonomic constraint.

Chetaev received the Lenin Prize in 1960. He was awarded the Order of Lenin, the Order of the Red Banner of Labor, and several medals.