Optimal design of the positions of the hoops for a hydraulic pipelines system

This paper focuses on decreasing the vibration and improving the dynamics performances for a hydraulic pipelines system. The parametric model of the hydraulic pipelines system under the random excitations is constructed and the dynamics characteristics are obtained by the finite element analysis, then an optimization model is presented to reduce the vibration by rationally designing the positions of the hoops in the pipelines system. The dimensions determining the locations of the hoops are defined as design variables, and the dynamics performances, such as the maximum displacement, the maximum axial stress, the maximum shear stress, the maximum axial strain, the maximum hoop strain, the maximum shear strain and the failure probability of the first passage are regarded as nonlinear constraints whereas the failure probability of cumulative fatigue damage is viewed as an optimization objective. The results show that the dynamics performances of the hydraulic pipelines system are distinctly improved by the optimization procedure, such as, the maximum displacement and velocity are reduced by 67.5% and 58.6%, respectively, and the maximum axial stress and strain are both decreased by 61.5% while the maximum shear stress and strain are reduced by 66.1%, and the failure probability of the first passage and cumulative fatigue damage are allayed by more than 99%, etc.