On the large-amplitude vibration of rotating pre-twisted graphene nanocomposite blades in a thermal environment

Vibration analysis of rotating pretwist FG sandwich blades operating in thermal environment

A quasi-3D dynamic model for free vibration analysis of rotating pre-twisted functionally graded blades

This paper investigates the vibration control of a rotating functionally gradient material (FGM) beam under thermal environment by using an enhanced active constrained layer damping (EACLD) treatment. The present model is extended from a newly developed dynamic model for composite EACLD beams. The difference is that the base beam is composed of temperature-dependent FGM that was widely used in the aerospace industry as advanced heat-resisting composite and the temperature dependence of viscoelastic material in the constrained layer is also considered. The active piezoelectric layer has edge elements at both ends, which are modeled as equivalent springs and mass points. The Lagrange’s equation is used to derive the dynamic equations of the system and the deformation of the beam is described by the assumed-mode method. Based on the rigid-flexible coupling dynamic theory, the dynamic responses of the rotating FGM beam with various temperature differences are investigated. Simulation results show that the vibration suppression performance of the EACLD beam is better than the ACLD beam. The equivalent springs have more significant influences on the structural vibration suppression effect than the mass points. The larger the temperature difference is, the larger the thermal induced flutter of the structure is. The influences of VEM damping layer thickness, rotating speed, and control gain on the vibration of the structure with EACLD treatment are also discussed.

Vibration suppression of a rotating functionally graded beam with enhanced active constrained layer damping treatment in temperature field

Three-dimensional vibration analysis of rotating pre-twisted cylindrical isotropic and functionally graded shell panels

Quasi-3D dynamic analysis of rotating FGM beams using a modified Fourier spectral approach

A hybrid active sound quality control system, in which a hybrid feedforward and feedback structure is applied, can not only be used in cases where the line-spectrum noise is obtained easily with reference sensors, but it can also improve the comfortability of noise and eliminate unexpected Gaussian random noise. However, the traditional structure for a hybrid active sound quality control system, whereby a reference signal in the feedback control structure is synthesized by the output signals of the feedforward control filter, feedback control filter, and line-spectrum noise cancellation control filter, introduces couplings of the three control filters. To remove the coupling interactions of the feedforward and feedback control structures and to reduce the complexity of the control system, two modified structures with less computational complexity or a smaller increase in computation are investigated in this paper. The first one involves a simplified structure in which the reference signal in the feedback control structure is replaced by the summation of the residual error signal and the output signal of the line-spectrum noise cancellation control filter, and the second one is a modified structure which integrates the output signals of the feedback control filter and the line-spectrum noise cancellation control filter for the reference signal in the feedback control structure. Numerical simulations are carried out to show the performance of the modified structures. The results illustrate that the two modified structures have the ability to cancel Gaussian random noise and to reduce or enhance the amplitude of line-spectrum noise to promote sound quality. Moreover, a simplified structure with a new leaky filtered-x least mean square (FxLMS) algorithm is proposed to upgrade the noise reduction performance and elevate stability in the feedback control structure. The effectiveness of the proposed algorithm also is proven by the simulation results.

https://www.mdpi.com/2076-3417/10/2/510/pdf

Modified Structures for Hybrid Active Sound Quality Control System Disturbed by Gaussian Random Noise

The invention aims to provide a ship acoustic feature intelligent active control method. According to the control method, a perception sensor is used for detecting acoustic and environmental information such as noise signals, pressure and temperature nearby a ship body under the water surface; an acoustic analysis and feature extraction module is used for extracting required radiation noise signals and acoustic situation information nearby the ship body; a control module generates signals at specific frequency and amplitude through an adaptive control algorithm according to the acoustic features and the acoustic situation information and finally realizes control over the acoustic features through a driving module and a transducer. Through the ship acoustic feature intelligent active control method, the voice print features of a ship can be changed to realize acoustic false camouflage for cheating and confusing the opposite side; moreover, noise nearby the ship body under the water surface can be actively offset when necessary to cut down acoustic feature signals of the ship body and conceal itself to achieve intelligent acoustic stealth. Thus, the intelligent active control and acoustic stealth performance of the ship can be improved.

Ship acoustic feature intelligent active control method

The invention aims to provide a ship structure acoustic radiation characteristic intelligent active control method which is used for detecting ship vibration noise, pressure, temperature, and the likeacoustic and environmental information using perception sensors, extracting required ship radiation noise signals and acoustic situation information through an acoustic analysis and feature extraction module, generating signals with specific frequency and amplitude by using a self-adaptive control algorithm according to the ship radiation noise signals and the acoustic situation information usinga controller, and finally controlling the acoustic radiation characteristics of the ship structure through a driving module and an active actuator. According to the method, ship voiceprint characteristics can be changed, acoustic false indication camouflage for spoofing and puzzling the opposite side can be realized, and ship radiation noise reduction, acoustic characteristic signal reduction, hiding and intelligent sound stealth can be realized when necessary, so that the ship intelligent active control and sound stealth performance can be effectively improved.

Li Shanjun

Papers

Quasi-3D dynamic analysis of rotating FGM beams using a modified Fourier spectral approach

Vibration analysis of rotating pretwist FG sandwich blades operating in thermal environment

Modified Structures for Hybrid Active Sound Quality Control System Disturbed by Gaussian Random Noise

Ship acoustic feature intelligent active control method

Ship structure acoustic radiation characteristic intelligent active control method