Energy method of some dynamic strengh calculations

Abstract

The known energy method based on the law of mechanical energy conservation of the mechanical system with one degree of freedom is generalized in the article, that makes it possible to decide the questions of natural frequencies and dynamic coefficient at different types of deformations. Considering Hooke's law on dynamic loading true and deformations and tensions increase gradual, (having potential energies on a static loading), we consider impact potential energy equal to initial kinetic energy of the mechanical system. Dynamic coefficient at torsion, flexural and longitudinal impacts has been got, and the literary source is indicated for the flexural impact in different points of a beam, taking into account the masses of the struck bodies. The obtained maximal stresses obtained at torsion and longitudinal impacts testify that in contrast to static stresses dynamic stresses at impact depend on the volume (but not on the area) of the struck body. Attention is drawn to the circumstance, that the dynamic coefficient at vibrations depends on natural frequency. Therefore the designers of machines must select inertness and other properties of the studied objects so that natural frequencies did not coincide with the shaft rotation frequencies and with the disturbance factors frequencies. Algorithm of calculations of dynamic–response factor at impact taking into account the struck body mass as well as algorithm of getting natural frequencies of longitudinal and torsion, flexural vibrations for some widespread calculation charts have been offered. The material of the article is taken from the known sources and generalized in a condensed form, (suitable for students and beginning designers) with the purpose of implementation of strength calculations of dynamic models with one degree of freedom