Fluid-conveying pipeline natural frequency optimization method based on discrete stiffness of elastic supports

Objective This paper aims to address the problem of the unsatisfactory vibration reduction (i.e., unsatisfactory optimal assignment of natural frequencies) using a continuous-stiffness based optimal natural frequencies assignment method. As the stiffness parameter is often discretized in implementation, this paper proposes a novel method for optimizing the natural frequency of fluid-conveying pipelines based on the discrete stiffness of the elastic supports.

Methods The proposed method uses the derived sensitivity formula of the target natural frequency to the stiffness parameters as the core algorithm, and takes the continuous-optimal stiffness parameters as the initial value. The discrete-optimal stiffness parameters of the elastic supports are solved by minimizing the disturbance deviation between the natural frequency and target frequency. The proposed method is then demonstrated by employing both numerical and experimental models of a U-shaped fluid-conveying pipeline.

Results The results show that the discrete-optimal stiffness parameters obtained by the proposed method can accurately achieve the optimization of the first two natural frequencies of the U-shaped fluid-conveying pipeline with a maximum deviation of no more than 2%.

Conclusions The proposed method is proven to have a fast computation speed, good convergence, and the ability to significantly reduce the disturbance deviation of the assigned natural frequencies, providing an effective solution to the problem of unsatisfactory optimal natural frequency results caused by errors between calculated continuous-optimal stiffness and discrete stiffness in actual engineering.