The paper deals with determination of specific material properties of a complex material architecture consisting of the elastic layer of finite thickness, the thin viscoelastic layer and the porous halfspace. Those pr...
详细信息
ISBN:
(纸本)0819417912
The paper deals with determination of specific material properties of a complex material architecture consisting of the elastic layer of finite thickness, the thin viscoelastic layer and the porous halfspace. Those properties should sustain specific external thermomechanical loadings.
Analytical and experimental studies undertaken for controlling noise in the interior of a 3D enclosure with a flexible boundary are presented. The rigid boundaries are constructed from acrylic material, and the flexib...
详细信息
ISBN:
(纸本)0819417920
Analytical and experimental studies undertaken for controlling noise in the interior of a 3D enclosure with a flexible boundary are presented. The rigid boundaries are constructed from acrylic material, and the flexible boundary is constructed from aluminum materia. Noise generated by an external speaker is transmitted into the enclosure through the flexible boundary and active control is realized by using Lead Zirconate Titanate piezoelectric actuators bonded to the flexible boundary. Condenser microphones are used for noise measurements. For panel and cavity controller modes, analog controllers based on feedforward schemes using acoustic error signals are developed and discussed.
This paper studies the vibration control of a flexible beam using a constrained viscoelastic damping treatment and layered shape memory alloy (SMA). The SMA layer is used as an actuator, which is capable of changing i...
详细信息
ISBN:
(纸本)0819417920
This paper studies the vibration control of a flexible beam using a constrained viscoelastic damping treatment and layered shape memory alloy (SMA). The SMA layer is used as an actuator, which is capable of changing its elastic modulus and recovery stress. A linear control law is determined based on optimal regulator theory. The control results are discussed.
A new and novel quasi-static (or passive-adaptive) control strategy using embedded piezoelectric actuators to alter the vibration response of a composite beam model is analytically investigated. Non-linear equations o...
详细信息
A new and novel quasi-static (or passive-adaptive) control strategy using embedded piezoelectric actuators to alter the vibration response of a composite beam model is analytically investigated. Non-linear equations of motion of the composite beam are developed, which incorporate the influence of initial in-plane loads generated by the piezoelectric layers. It is shown that the natural frequencies of a simply-supported composite beam can be Varied substantially by applying a voltage to the piezoelectric layers. The influence of the embedded piezo-actuator thickness on the performance of the passive-adaptive control strategy is discussed. The application of three practical piezoelectric materials, piezo-ceramics (PZT), polyvinylidene fluoride (PVDF) and copolymer, are also discussed.
The mathematical model of a flexible beam covered with shape memory alloy (SMA) layers is presented. The SMA layers are used as actuators that are capable of changing the elastic modulus and recovery stress, thus chan...
详细信息
ISBN:
(纸本)0819417920
The mathematical model of a flexible beam covered with shape memory alloy (SMA) layers is presented. The SMA layers are used as actuators that are capable of changing the elastic modulus and recovery stress, thus changing the natural frequency of and adjusting the excitation to the vibrating beam. A linear control law is determined based on optimal regulator theory. The control results are discussed.
One major problem in magnetic resonance image equipment is the high-level noise borne by the vibration of the cylindrical shell to support coils for gradient magnetic fields. The vibration of the shell is excited by t...
详细信息
ISBN:
(纸本)0819417920
One major problem in magnetic resonance image equipment is the high-level noise borne by the vibration of the cylindrical shell to support coils for gradient magnetic fields. The vibration of the shell is excited by the Lorentz force between the pulse current applied to the coils and the main magnetic field. In order to suppress the noise inside the cylindrical shell, it is aimed to control the vibration of the shell. In this paper, simulation is carried out on the vibration control of the shell by using distributed piezoelectric actuators. The actuators produce bending moment or in-plane force when pulse voltages are applied synchronously with the pulse current of the coils. Coupling of actuators and vibration modes, and parameter optimization are also discussed. The simulation results show that the vibration level is successfully reduced in the frequency range of 400 approximately 1200 Hz.
This paper first presents the methodology to design and optimize a feasibility demonstrator for low frequency active control of a composite plate. The demonstrator has been achieved and the experimental results are sh...
详细信息
ISBN:
(纸本)0819417920
This paper first presents the methodology to design and optimize a feasibility demonstrator for low frequency active control of a composite plate. The demonstrator has been achieved and the experimental results are shown. The major steps to design a smart structure are described. A review of active control strategies with associated hardware requirements as well as different implementation methods shows that the final system is strongly related to the problem to be solved due to the complexity of the structure, the computer efficiency and the expected final response quality. The aim of the study is to prove the feasibility to control the low-frequency (less than 100 Hz) vibrations of a carbon/epoxy composite plate under various mechanical excitations. Experiments were driven to characterize mechanically the composite plate as well as the PZT piezoceramic actuators. An original approach with dual analog-digital controller has been designed and realized, resulting in a simple system: microprocessor programmable switched capacitor low-pass filters and a PC fitted with a timing and digital interface board were used for the controller. Performances using analog filters and a least mean square algorithm are presented.
The approach to modeling and control of smart flexible structures presented in this paper is based on the claim that an intelligent structure requires an internal knowledge of self which may be acquired from local mod...
详细信息
ISBN:
(纸本)0819417912
The approach to modeling and control of smart flexible structures presented in this paper is based on the claim that an intelligent structure requires an internal knowledge of self which may be acquired from local models of substructure dynamics. This approach employs analog models of the flexible structures in model-based controller designs. These analog models are created using VLSI circuitry and are embedded into the physical structure. The model of a composite structure is formed by interconnecting the analog models of single finite elements. The goal of this research is to devise such analog VLSI circuit models of single elements that can be easily connected together to model flexible structures. The circuit models are highly repetitive and, thus, are amenable to integration on a VLSI chip. A simple finite element circuit model has been integrated on an analog VLSI chip. Results clearly show that the poles of the circuits correspond very closely with the theoretical poles of the beam.
This paper describes the use of MEMS in smartstructures. A smart skin concept is described in which an array of sensors and actuators may be incorporated onto the surface of a structure. A hear flux sensor array conc...
详细信息
ISBN:
(纸本)0819417971
This paper describes the use of MEMS in smartstructures. A smart skin concept is described in which an array of sensors and actuators may be incorporated onto the surface of a structure. A hear flux sensor array concept is described, and shear stress sensors are presented as examples of MEMS devices for structure surfaces. MEMS devices may also be embedded into a structure. For example, pressure and temperature memory sensors are presented for a smart-tire application, in which the MEMS device may be embedded into the tire to provide tire-monitoring capabilities.
Matrix second order systems arise in a variety of structural dynamics and control problems. The analysis and design of such systems is traditionally done in frequency domain or in time domain (state space framework). ...
详细信息
ISBN:
(纸本)0819417912
Matrix second order systems arise in a variety of structural dynamics and control problems. The analysis and design of such systems is traditionally done in frequency domain or in time domain (state space framework). The formulation of the control design problem in matrix second order form (i.e., configuration space framework) has many advantages over first order state space form. In this paper, a novel approach for designing a stabilizing controller in a second-order model of piezoelectrically controlled flexible beam is proposed.
暂无评论