Abstract
Fatigue failure of a hydraulic hose systems, caused by violent vibrations, has become a critical factor creating operational and maintenance cost for the end user of rock drill equipment. Similar behavior is also appearing in, for example, forestry machines. Hoses are used as parts of the energy feeding system in machines such as the ones use for mining and civil construction operations. This work aims to create an understanding of the dynamic behavior of a selected hydraulic hose. The numerical modeling approach selected includes a boundary element method approach in the fluid-elastic analysis of the dynamics of a pressurized hose with conveying fluid. Experimental modal analysis was used to validate the numerical model. Pre-tension and pressure-induced tension were monitored with an in-house-developed strain gauge–based load cell. The analysis and experiments show that a complex coupling, of pure structural bending modes, appears when the hose is subjected to internal flow. Some of the modeshapes show a circular motion of the hose cross sections. As shown in this article, these coupled modes become increasingly sensitive to external or internal excitation with increasing flow rate. To illustrate the strength of the proposed approach, the second part of the work in this article presents a parametric study of hose dynamics for hoses with typical dimensions used in industrial applications. This investigation of how different parameters influence the dynamic characteristics of hydraulic hoses shows, for example, that hose end-support stiffness has a large impact on the stability and dynamic behavior of the hose. A soft support tends to create a static instability–type behavior where the lowest frequency mode frequency decreases to levels close to zero with increasing flow speed. Pre-tension of the hose has a stabilizing effect on the hose dynamics. In the case when the internal pressure of the hydraulic hose does not generate tension of the hose, then the increase or decrease in the internal pressure has limited influence on the hose dynamics: this is at least a conclusion valid in the investigated 100–210 bar pressure range. In addition, a smaller diameter hose is more sensitive than a larger diameter hose, and this is valid as long as the pre-tension is high enough to maintain static stability in the entire flow rate range.
Highlights
Vibration phenomena requiring understanding of fully coupled fluid–structure systems, including fluidconveying tubes, pipes, and so on, are a dynamic type of problem that have been investigated by numerous authors
This is due to the increasing need for stability and reliability in a broad range of industrial applications: applications ranging from nuclear reactors, heat exchangers, ocean mining pipes, and drill strings as described by, for example, Paidoussis,[6] Xia et al.,[7] and Zhang et al.[8]
The phenomena of dynamics related to the internal and or external axial flow fluid–structure interaction (FSI) is a relatively new area of research unlike the case of vibration of slender structures subjected to cross flow
Summary
Vibration phenomena requiring understanding of fully coupled fluid–structure systems, including fluidconveying tubes, pipes, and so on, are a dynamic type of problem that have been investigated by numerous authors.
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