Fluid-Induced Vibration of a Hydraulic Pipeline with Piezoelectric Active Constrained Layer-Damping Materials

The basic structure of a pipeline is complex due to the narrow installation space of a pipeline system. Thus, a considerable number of complex pipelines are adopted in a pipeline system. When a hydraulic pipeline works, it is impacted by fluid, which produces vibration. It is necessary to implement an effective method to control the vibration of a pipeline system. In recent years, the research on active constrained layer damping (ACLD) technology is increasing. However, there are few studies on the vibration characteristics of the ACLD pipeline system conveying fluid. The damping and vibration characteristics of ACLD pipeline system conveying fluid are studied in this paper. Considered the influence of the fluid–structure interaction, the motion equations can be derived, and the finite element model established of the pipeline based on ACLD treatment. The effect of the elasticity modulus, the thickness of the viscoelastic and constrained layer, the length and position of the ACLD patch, the velocity and pressure of fluid, and the voltage for the constrained layer, are all considered. The results show that ACLD technology has great damping influence on the conveying fluid pipeline.

Dynamic modelling and analysis of smart carbon nanotube-based hybrid composite beams: Analytical and finite element study

In this work, the carbon nanotube-based hybrid carbon fibre-reinforced composite smart beam constraining the layer of an active constrained layer damping treatment is investigated using an in-house finite element model based on first-order shear deformation theory. The effect of in-plane and transverse-plane actuation of the integrated active constrained layer damping treatment layer on the damping characteristics of the novel smart cantilever hybrid carbon fibre-reinforced composite beam is considered. The parameters affecting the damping characteristics of the hybrid carbon fibre-reinforced composite substrate beam such as the volume fraction of both carbon nanotubes and carbon fibre, and the aspect ratio are also studied. Besides, the micromechanical model based on the mechanics of materials approach is developed to estimate the effective elastic coefficient of novel hybrid carbon fibre-reinforced composite lamina. The effective properties of hybrid carbon fibre-reinforced composite are predicted quantitatively by considering non-bonded interaction formed between carbon nanotubes and the polymer matrix. It is revealed that due to the incorporation of carbon nanotubes into the epoxy matrix, the effective longitudinal, transverse and shear properties of the hybrid carbon fibre-reinforced composite lamina are significantly enhanced. Our outcomes explore that the damping performance of the laminated hybrid carbon fibre-reinforced composite smart beam considering the incorporation of carbon nanotubes shows substantial improvement as compared to the base composite. To bring more clarity, the quantitative relative performance of hybrid carbon fibre-reinforced composite and base composite is presented. Our fundamental analysis sheds the light on the opportunities of developing efficient, high-performance and lightweight carbon nanotubes-based micro-electro-mechanical systems smart structures such as sensors, actuators and distributors.

Vibration and Damping Analysis of Pipeline System Based on Partially Piezoelectric Active Constrained Layer Damping Treatment

Pipelines work in serious vibration environments caused by mechanical-based excitation, and it is thus challenging to put forward effective methods to reduce the vibration of pipelines. The common vibration control technique mainly uses the installation of dampers, constrained layer damping materials, and an optimized layout to control the vibration of pipelines. However, the passive damping treatment has little influence on the low frequency range of a pipeline system. Active control technology can obtain a remarkable damping effect. An active constrained layer damping (ACLD) system with piezoelectric materials is proposed in this paper. This paper aims to investigate the vibration and damping effect of ACLD pipeline under fixed support. The finite element method is employed to establish the motion equations of the ACLD pipeline. The effect of the thickness and elastic modulus of the viscoelastic layer, the laying position, and the coverage of ACLD patch, and the voltage of the piezoelectric material are all considered. The results show that the best damping performance can be obtained by selecting appropriate control parameters, and it can provide effective design guidance for active vibration control of a pipeline system.