Natural Frequency Analysis of Pipe with Different Boundary Conditions Using Analytical and Finite Element Method

Abstract

AbstractVibration-induced failures in piping systems often result from the excitation of natural frequency of an individual piping span. In this paper, vibrations characteristics of pipe with different pipe end conditions have been analysed using the analytical and finite element approach. The natural frequencies of the pipe are investigated by varying the length of the pipe with fixed-free end support and fixed–fixed end support, with and without fluid. Finite element models of the pipe structure are prepared using ANSYS Workbench software. The natural frequency for fixed-free pipe is much lower than fixed–fixed pipe for both with and without fluid. The natural frequency for pipe with fluid is lower than the pipe without fluid for both boundary conditions. The results are compared with analytical method in order to validate the finite element model. A good agreement is found between the analytical and the numerical results. Linear equations that predict the first natural frequency are formulated using regression analysis. It is found that the regression equations describing the correlation of the first natural frequency on the length of the pipelines has the form of power function for all pipe end conditions. This approach can be used with subsequent dynamic analyses such as response spectrum analysis or harmonic analysis for further research.