# Vibration Control of an Aero Pipeline System with Active Constraint Layer Damping Treatment
## 2 Materials and Methods
### Experimental Validation of Active Constraint Layer Damping Treatment  
The vibration control of the pipeline is implemented by the ACLD patches. The structural parameters and control parameters of the active constraint layer damping will significantly affect the vibration control effect. To verify the vibration damping performance of the active constraint layer damping, a vibration control platform is set up as shown in Figure 9. The control system mainly consists of a vibration control part and a vibration monitoring part.  
A diagram of a vibration control platform for a pipeline with ACLD pat  
Figure 8: Acceleration response under excitation from base.  
Figure 9: Schematic diagram of vibration control platform for pipeline with ACLD patches.  
The hardware of the vibration control platform mainly includes the following equipment:  
1. Vibrostand: Provide a sinusoidal excitation for the pipeline. Output excitation frequency range: 5 to 5000 Hz.
2. Sensors: The sensors used in this paper include acceleration sensors and piezoelectric ceramic sensors.
3. Signal collector: (1) The voltage acquisition and output module comprise 16 voltage input channels and 2 output channels, wherein the input channel is used for feedback vibration response of the pipeline, the output channel is used for outputting control signals through the controller; (2) The acceleration acquisition module has 8 acceleration input channels to monitor the vibration of the pipeline.
4. Controller: The controller is used as a lower computer to run the control program. The input vibration signal is computed to obtain the control voltage signal. The controller is a National Instruments PXI controller.
5. Voltage amplifier: Amplify the control voltage signal outputted by the controller. The voltage amplification factor can be up to 15 times. The voltage signal input range is 0-10 V, and the no-load full-scale bandwidth is 1000 Hz.  
The software the vibration control platform includes: vibration monitoring software and control software. The function of the vibration monitoring software is to collect, process, display and save the vibration response data of the pipeline. The vibration control software functions are: signal acquisition, signal filtering, signal processing, overload protection and signal output.  
Vibration monitoring software mainly consists of channel parameter setting, acceleration data acquisition, strain data acquisition and data storage. The channel name, sensor sensitivity, and sampling frequency of the data acquisition need to be set in the channel parameter setting part. The data acquisition part displays the time and frequency domain of the collected data. The data storage part names and saves the collected data files. Hardware timing single-point sampling is used as the voltage sampling mode. The hardware timing single-point sampling enables continuous sampling or sample generation. Unbuffered hardware timing sampling can eliminate the time delay caused by data buffering.  
The vibration control software mainly consists of channel parameter, sampling frequency setting, data filtering, control waveform adjustment, overload protection and data display. The voltage input/output channel name and the channel sampling frequency need to be set in the channel parameters setting part. Since the piezoelectric material is used as the sensor to collect the voltage,  
Figure 10: Diagram of experiment platform.  
there is a common signal interference, so the collected data needs to be filtered. A waveform chart is set on the front panel to display the collected data.  
As is shown in Figure 11, the ACLD patches is adhered to the middle and root surface of the pipeline, the piezoelectric sensor is adhered to the middle surface of the pipeline and is opposite to the ACLD patches. Two ends of the pipeline are clamped through the fixed support.