Analysis of Flexible Metal Hoses Frequency Characteristics

The article describes various types and sources of flexible metal hoses (FMH) vibration. Depending on the direction of vibration displacements, basic variations of sleeves vibration are identified: transversal, longitudinal and torsional. The distinguished forces, that excite vibration in FMH, acting on it, are divided into static and dynamic loads. The most common type of vibration - transverse vibration of flexible sleeves is considered in more details. Also, the ripples - one of the main causes of transverse vibration, which significantly degrade hydraulic performances of pipeline communications, are investigated. The paper presents the analysis of characteristics of the bending and longitudinal stiffness, which implies that the stiffness increases with increasing internal pressure, the diameter of the sleeve and the number of braids. To determine frequency characteristics of FMHs, the bar, with reduced parameters of elasticity and mass, has been chosen as FMH mathematical model. The research results of an influence of various factors on the metal sleeves eigenfrequencies have been studied.