Multi objective optimization of the vibration analysis of composite natural gas pipelines in nonlinear thermal and humidity environment under non-uniform magnetic field

The fluid-conveying pipe is a fundamental dynamical problem in the field of fluid– structure interactions. In recent years considerable attention has been given to the lateral vibrations of pipes containing by a moving fluid. In this paper, the vibration analysis of composite natural gas pipeline in the thermal and humidity environment is studied. The effect of the non-uniform magnetic field is investigated. By applying the Hamilton’s principle, the equation of motion is derived for the pipe with the effects of both linear and non-linear stress temperature cases. The differential quadrature method (DQM) has been utilized in computing the results for the pipe conveying fluid. The Bees algorithm and Genetic algorithm NSGA II for multi-objective optimization of a pipe model are used. Sample results are presented for several cases with varying values of the system parameter. Results are demonstrated for the dependence of natural frequencies on the flow velocity as well as temperature change and humidity percent. The influence of temperature change on the critical flow velocity at which buckling instability occurs is investigated. It is concluded that the effect of temperature change on the instability of conveyed fluid pipe is significant.