An Integrated Control Study On The Noise Characteristics Of Elastic Cavity With ACLD

In recent years, with the development of large-scale digital informationprocessing technology, the new control theory and new materials, the constraintdamping (CLD) has been widely used in the structural acoustic active control. CLDis mainly divided into active constrained damping (ACLD) and passive constraineddamping (PCLD)，the difference of the ACLD and PCLD is that ACLD usespiezoelectric materials instead of general elastic constrained material in PCLD,twotypes of these structures can consume great amount of vibrational energy byviscoelastic layer shear deformation constrained, they have a great effect in inhibitingand reducing the structural vibration and noise. The study of this paper is to controlnoise of elastic cavity with ACLD, which uses advanced digital electronic technologyand a new type of smart piezoelectric materials, the control voltage of activeconstrainted layer PVDF come from master controller based on digital signalprocessor (DSP), the control system with adaptive, can be able to automaticallyadjust control variable to inhibit noise according to the intensity of noise, the maincontent of this study are the following：(1) using finite element method, based on the Hamilton principle and the principleof virtual work, established finite element dynamic equation of the active constrainedstructure (board, elastic cavity), and analyzed of its dynamic characteristics by digitalsimulation with Matlab programming。(2) analyzed of noise characteristics of an ideal elastic cavity with ACLD,studingthe effect of ACLD reducing cavity noise。(3)studied the acoustic characteristics control strategy of the ideal elastic cavitywith ACLD, solved modal damping ratio approximately,used modal damping ration tosimplify the dynamic equations, based on implified equation, then use the multivariateMIC single neural PID to control it。(4) designed the controller of acoustic characteristics integrated control of elasticcavity with ACLD, according to control requirements, to design main controller basedon large-scale digital processing DSP, and also designed new type smart piezoelectricsensors, smart piezoelectric actuators, and other appropriate auxiliary curcuit,copletedhardware design of the entire control system。(5) designed the control software of acoustic characteristics integrated control ofelastic cavity with ACLD,On the basis of the hardware circuit, according to thecontrol algorithm to design control software, the software combined with a variety ofadaptive algorithm, for example, model reconstruction, correction, and single nervePID control,so that the control of ACLD flexible structures become easy,despite of itscontrol model changed generally。 (6)experimental verification, based on the design of control systems and someexisting laboratory equipment, tested the sensor output voltage in the pure cavity andpartial active constrained damping conditions, as well as to test the output voltage ofpiezoelectric driver in partial active constrained damping, and also tested the soundpressure changes under a certain frequency range harmonic force to verify thecorrectness of the model, as well as the effectiveness of the control system andself-adaptive.The research methods used in this paper is mainly theoretical modeling,simulati-on,simulation and combining with experimental test, the designed control systemwhich used ACLD structure to reduce noise of elastic cavity has a lot of meaning andvalue in practical application.