# Vibration Control of an Aero Pipeline System with Active Constraint Layer Damping Treatment
## 1 Introduction
(2) controlling the vibration of the pipeline through the active control components. The research on the control method of ACLD structure is still insufficient. The control methods used by most researchers are PD control and simple LQC control. PD control is too simple, and simple LQC control is difficult to make optimal in practical applications due to various conditions [14; 15; 16]. The existing active vibration control on different objects [17; 18; 19; 20; 21] has a better control effect on low frequency, strong adaptability to the external environment, and can automatically follow the change of vibration characteristics [22]. The design flexibility is great, but the closed-loop control system has many links, and the stability of the system needs to be further improved. In recent years, some scholars have proposed a new active control method, that is, the active constraint layer damping (ACLD) treatment. The mechanism of this method is: (1) Actively adjusting the damping characteristic of the substrate through the active constraint layer damping. When the substrate vibrates, the viscoelastic damping layer takes shear deformation and dissipates the vibration energy. Meanwhile the deformation of the active constraint layer increases the shear deformation of the viscoelastic layer to improve the energy dissipation of vibration. (2) The active constraint layer damping treatment has a similar damping effect as an active damping control system. Due to the active control strategy, the ACLD structure not only greatly reduces the weight of the system, but also effectively enhances the dissipation of vibration energy. Some scholars [23; 24; 25] have analyzed the effectiveness of ACLD in vibration control from a structural perspective. Application of ACLD treatment on vibration control of different objects is also a major research area [26; 27]. These studies showed that: (1) ACLD can effectively suppress the vibration of the controlled structure; (2) the ACLD structure can suppress the vibration level of the passive structure more effectively than the pure passive damping structure; (3) The active control part of the ACLD structure is capable of adaptively adjusting the structural damping, while the passive control part can increase the gain and phase margin of the control system. However, existing research focused mainly on the damping mechanism of ACLD and its application on plates and cylindrical shells. Research about ACLD treatment and the influence of its control parameters in pipeline vibration control, especially in the field of aero pipeline system is less common. In this paper, a method of applying ACLD to vibration control of aero pipeline is proposed based on the vibration and stress distribution. The driving force transmission characteristics under different voltages were analyzed. The numerical calculation of the vibration control of the pipeline with ACLD patches under different voltages is carried out. The effectiveness of the proposed method on vibration control is verified, and the influence of control parameters and structural parameters on the vibration control effect is analyzed. The vibration control platform was built, and the voltage negative feedback control software and vibration monitoring software were developed. The influence of structure parameters and control parameters on the damping effect shows that the ACLD treatment has a favorable damping effect on the vibration of pipelines.