Friday 29 May 2015

29-may-1972 :- Death Of Stephen Timoshenko , Developed Timoshenko Beam Theory.

Stepan Prokopovych Timoshenko 
(December 22, 1878 – May 29, 1972) was a Russian engineer of Ukrainian origins. He is believed to be the father of modern engineering mechanics. A founding member of the Ukrainian Academy of Sciences, Timoshenko wrote seminal works in the areas of engineering mechanicselasticity and strength of materials, many of which are still widely used today. Having started his scientific career in the Russian Empire, Timoshenko emigrated to Yugoslavia during the Russian Civil War and then to the United States.

Timoshenko Beam Theory
The Timoshenko beam theory was developed by Russian scientist and engineer of Ukrainian ethnicity Stephen Timoshenko early in the 20th century. The model takes into account shear deformation and rotational inertia effects, making it suitable for describing the behaviour of short beams, sandwich composite beams or beams subject to high-frequency excitation when the wavelength approaches the thickness of the beam. The resulting equation is of 4th order, but unlike ordinary beam theory - i.e. Euler–Bernoulli beam theory - there is also a second order partial derivative present. Physically, taking into account the added mechanisms of deformation effectively lowers the stiffness of the beam, while the result is a larger deflection under a static load and lower predicted eigenfrequencies for a given set of boundary conditions. The latter effect is more noticeable for higher frequencies as the wavelength becomes shorter, and thus the distance between opposing shear forces decreases.

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