Semi-analytical dynamic modeling of parallel pipeline considering soft nonlinearity of clamp: A simulation and experimental study

Clamp is a crucial support structure to secure and connect the parallel pipeline system. Since the metal felt of the clamp is composed of metal rubber material, as well as the clamp structure using bolted connections, clamp is prone to cause nonlinear force during vibration. Nevertheless, no relevant paper has been reported to study the influence of soft nonlinearity of clamps on parallel pipelines. To bridge this gap, the present study introduces a novel semi-analytical dynamic model that effectively considers the influences of nonlinear clamps in parallel pipeline systems. The proposed model simulates the clamp's vertical hysteretic restoring force using the Bouc-Wen model. The clamp parameters are identified using Particle Swarm Optimization (PSO) with experimental and simulation errors as the objective function. Subsequently, the model is then validated by conducting modal and response tests. The numerical results are consistent with the experimental results. In order to prove the validation of the proposed model, experiments are conducted using dual clamps at different positions, and it can be observed that the nonlinear parameters of the clamps still meet the accuracy requirements. Moreover, the influences of fluid parameters on frequency are compared with the ANSYS software and the proposed model, and the influence trends exhibit consistency. By considering the nonlinear effects of clamps, the proposed model facilitates enhanced accuracy in predicting vibration responses.