It is demonstrated by experimental realization that vibration of the CD-ROM drive base can be effectively reduced by activating the proposed piezoelectric shunt circuit. It is experimentally verified that vibration of the HDD system can be effectively reduced by enabling the proposed piezoelectric shunt circuits.
N EW A DVANCES IN D ESIGN AND P REPARATION
OF E LECTRORHEOLOGICAL M ATERIALS
AND D EVICES
Abstract
I Design and Preparation of Electrorheological Materials 1 Introduction
Interestingly, the process of changing the viscosity or liquid-solid state of the ER fluid is reversible as soon as the applied electric field is removed. A popular characterization of the ER effect is to evaluate the rheological response with constant shear under an electric field.
2 ER Mechanisms
Polarization Mechanism
E H , where H0,Hp and Hc are respectively the vacuum dielectric constant and the real dielectric constant for particles and oil phase. The Maxwell–Wagner model is the simplest description of particle polarization, accounting for the bulk conductivity of the particles and fluid, as well as their dielectric constant.
Electric Double Layers and Water Bridge Model
When the field is removed, water is withdrawn due to surface tension or dissociative pressure. The water bridging mechanism gives good correspondence with many water-containing ER material systems, in which a reduced ER effect has been found with decreasing water content.
Conduction Model
The ultimate goal of ER mechanisms is to attempt to predict the yield stress and rheological properties of an ER fluid under electric and shear fields. Therefore, current mechanisms still cannot predict yield stress well based on the physical properties of ER suspension components and operating conditions such as field strength, temperature, frequency, etc.
3 Components of Electrorheological Fluids
But the ER effect or shear stress is relatively weak when the particle volume fraction is very low due to the difficulty of forming chain or fibrous structures. Particle shapes also have an influence on the ER effect according to theory and experimental results [28,29].
4 Design and Preparation of ER Materials
ER Materials Based on Molecular and Crystal Structure Design
- Inorganic ER Materials Aluminosilicates
- Organic ER Materials Polymeric semiconducting material
The ER effect of a typical Y-doped BaTiO3 ER suspension is ten times greater than that of a pure BaTiO3 ER suspension. The dielectric properties of these host-guest complexes also demonstrated that the properties of the guest can influence the ER effect.
ER Materials Based on Nanocomposite and Hybrid Design
- MMT Based Nanocomposite ER Materials
- Kaolinite Based Nanocomposite ER Materials Polar liquid interacted kaolinite ER material
- Mesoporous Silica Based Nanocomposite
Recently, Xiang et al [68] designed a new type of montmorillonite ER nanocomposite material coated with TiO2 nanocrystal (MMT/TiO2) that showed high ER effect as well as good temp. Because no ions are introduced into the kaolinite/titanium oxide core/shell material, its current density is very low (5ȝA/cm2 below 4kV/mm) and thus the ER effect is quite low.
Molecular-Scale Organic/Inorganic Hybrids
- Polysaccharide / Titania Hybrid Gel
- Glycerol/Surfactant/Titania Hybrid Gel
This advantage of glycerol will merit to increase the dielectric properties of titanium gel and avoid the large leakage current density through ER liquid as adsorbed water. Furthermore, glycerol's high boiling point and low volatility may merit the temperature stability of ER fluid at high temperature.
II Design and Manufacturing of Electrorheological Devices 1 Electrorheological Self-Coupled Dampers
- Introduction
- Working Principle of Self-Coupled ER Dampers
- The First Generation Product: Adaptive ER-piezoceramic Damper
- Spring-Direct-Pressing Type Damper [101]
- Wedge-Push Type Damper [102]
- Vibration Suppression Properties
- The Second Generation Product: Self-Coupled ER Damper
- Configuration of the Self-Coupled ER Damper [106]
- Vibration Properties of Dampers [107]
- Theoretical Model for the Self-Coupled ER Damper [107]
This is probably caused by non-linear factors in the shock absorber system, such as friction between the wedge piston and the key of the ceramic box, the non-linearity of the torsional force compared to the vibration displacement, and the fluctuation of the ER fluid in the shock absorber. Simulation results for vibration of self-coupled ER damper (a) without piezo-ceramic output voltage and (b) with piezo-ceramic output voltage.
2 Flexible Sound-Tunable ER Composite Layer 2.1 Introduction
Sound Tunable Characteristics of Flexible ER Layer [131]
The vibrational properties of ER fluid under an electric field are controlled by the electrically induced viscoelasticity in the material. Thus, the coupling vibration in the upper plastic film is amplified after the electric field is applied.
Vibration-Radiation Model of the ER Layer [134]
The vibration in the upper plastic film generated by the ER fluid is therefore weak and leads to a low sound radiation from the surface of the upper plastic film [133]. The complex viscoelasticity in ER fluids causes the complexity in the vibrational properties in the ER layer.
The sound pressure at point P, which is on the center-vertical axis and at a distance z from the center of the piston, can be expressed as [133].
Frequency (Hz)
Sound radiates directly from the surface of the top plastic film, so the speed of the top plastic film is of primary importance and can be calculated as For example, the vibrations of a four-sided attached ER layer can be much more complex, and the storage and loss moduli vary with frequency.
Summary
These tunable characteristics provide a methodology for designing phononic crystals with a tunable acoustic gap in the low-frequency region. For example, these ER layers could be used as inclusion layers in layered one-dimensional phononic crystals or used in a unit cell composite as a design element in multidimensional phononic crystals.
Acknowledgements
Within the 80–150 Hz band, the flexible ER liquid thin film exhibits obvious tunable properties. In addition, ER's own flexible thin films can be used to develop controllable acoustic devices such as audio amplifiers and phase tuners.
Zhao, Temperature effect of TiO2 rare earth doped electrorheological fluids, Journal of Physics D: Applied Physics. Zhao, Temperature effect of TiO2 rare earth doped electrorheological fluids, Journal of Physics D: Applied Physics.
E LECTROELASTICITY P ROBLEMS
OF P IEZOELECTRIC M ATERIALS AND A F ULL
S OLUTION OF A D IELECTRIC C RACK
1 Introduction
Furthermore, in Section 5, the COD intensity factor is proposed as a suitable fracture criterion, indicating that when field stress is prescribed, applied positive electric field reduces fracture toughness, while negative electric field increases fracture toughness. However, when far-field deformation is prescribed, applied positive electric field increases fracture toughness, while negative electric field decreases fracture toughness.
2 Electroelasticity Problems
Basic Equations
However, when far-field stress is described, the applied positive electric field increases the fracture toughness, while the negative electric field decreases the fracture toughness. transversely isotropic piezoelectric ceramics takes the following form. 3c) Here the stress and electric field components can be expressed in terms of elastic displacements and electric potential, respectively, with the following equations.
Boundary Conditions
Due to the opening of cracks, the interior of the crack, such as vacuum, can actually be treated as a dielectric; so there is an electrical potential difference across the opening crack. Note that ∆u and ∆φ are final values of crack opening displacement and potential difference across the crack surfaces behind the deformation, not before the deformation.
3 Two-Dimensional Problems
- Dielectric Crack Problems
- Electric Displacement at the Crack Surfaces
- Full Electroelastic Field in the Entire Piezoelectric Plane
- Asymptotic Crack-Tip Field
It is clear that a comparison of (73b) and (80a) shows that σzz(x,0) at the crack plane is independent of applied electric charge and material properties. 6 it is seen for a vacuum crack, the electrical displacements at the crack surfaces lie between those for an impermeable crack and a conductive crack.
4 Three-Dimensional Problems
General Solution
The above system of partial differential equations has non-trivial solutions, so the coefficients must satisfy the relations, which are the same as in the two-dimensional case. Once generalized harmonic functions Fj are found, the elastic displacement and potential are expressed in terms of Fj as follows.
Dielectric Crack Problems
Furthermore, in the case of prescribed strains∞ = 2×10−4, the impermeable crack does not close for E∞ < 18 kV/cm for the two-dimensional case, while the crack closes at about E∞ = 14 kV/cm for the two-dimensional case. a three-dimensional example that can be found in Fig. Therefore, explicit analytical expressions for the entire electroelastic field in terms of elementary functions are given.
Asymptotic Crack-Tip Field
From the above, the stress, strain, electric displacement and electric field intensity factors near the crack front are according to their definitions. This means that the applied mechanical load strongly affects the electrical displacement singularity near the crack front, and its intensity factor also changes with the dielectric permittivity of the crack interior.
5 Fracture Criterion
The reason is that the applied positive field can induce the piezoelectric ceramic to expand along the pole direction and help crack growth when the cracked piezoelectric body is not restrained. Despite the above, if the cracked piezoelectric body is fixed at a certain distance, which can be described by prescribed elastic strain or displacement, this, in turn, causes the cracked piezoelectric stiffness to expand along the opposite direction , i.e.
6 Conclusion
It is interesting to note that all curves intersect at E0 = 0. This suggests that the values of KCOD under purely mechanical loading are the same for any dielectric crack in a piezoelectric solid. Effects of electric field on crack growth for a penny-shaped dielectric crack in a piezoelectric layer J.
A NALYSIS OF H YBRID A CTUATED L AMINATED P IEZOELECTRIC S ANDWICH B EAMS AND A CTIVE
V IBRATION C ONTROL A PPLICATIONS
Since an orthorhombic crystal system of mm2 class has five piezoelectric constants and they can couple electric fields with strain fields, studies have been done to investigate new smart structure concepts using them (Barrett, 1992; Zhang and Sun Benjeddou et al Aldraihem and Khdeir, 2000, Raja et al., 2002). Intelligent constructions of sandwich structures are proposed, in which piezoelectric materials are either bonded to the surface or placed as a core together with the regular soft-core material (Koconis et al., 1994).
2 Extension and Shear Actuations
- Basic Equations and Weak Formulation
- Constitutive Models
- Stress-Strain Relations for Extension Actuated Lamina (EAM) The active lamina properties with respect to material axes are defined as follows
- Stress – Strain Relations for Shear Actuated Lamina (SAM)
- Stress Resultants of Hybrid Actuated Sandwich Beam
- Electric Field to Potential Relations
- Finite Element Formulation for Hybrid Actuated Beam
- Displacement Field Equations and Kinematic Relations
- Smart Sandwich Beam Finite Element
The shear strain of the sandwich beam cross section is obtained from the shear deformation of the core laminate using the small shear approximation. I I is the mean potential, I1i Ii Ii is the potential difference (Figure 3), and hk is the distance of the kth layer from the mid-plane of the sub-laminate.
3 Bending and Free Vibration Behaviour of Smart Sandwich Beams
Bending Behaviour of Hybrid Actuated Sandwich Beams
In the second analysis, a hybrid-operated cantilevered sandwich beam is constructed with superimposed slide and extension actuators and the beam configuration is shown in Figure 9. The Clamped-Free (C-F), Clamped-Clamped (C-C), Clamped-Hinged (C-H) and Hinged-hinged (H-H) boundary effects are included in the analysis.
4 Distributed Active Vibration Control
Active Control Strategies
- Displacement Feedback (Proportional Control)
- Velocity Feedback (Derivative Control)
The electric charge (q) indicates the displacement of the system, so the velocity of the charge (dq/dt = i: sensor current) is the velocity of the system. In velocity feedback control, the trigger signal is in phase with the system velocity (900 phase guide with system lag), so that a dissipative force (active damping) is introduced into the system (see Figure 17 b).
State-Space Formulation
- State-Space Models in Physical Domain
It can be observed that the sensor patch senses the charge induced due to the associated node displacements and outputs it as sensor voltage. The speed information from the sensor patch can be further obtained by differentiating the charge signal using a differentiator (analog or digital).
ª ºªº
44) 4.2.2 State-Space Models in Modal Domain
- Modal Control
- State Feedback
- Output Feedback
- Condensation of System Matrices
- Pole Placement and Mode Shape Control
- Active Vibration Control and Modal Response Analysis
- Pole Placement and Mode Shape Control
The system response u(t) can be represented as a linear combination of the set of desired Eigenvectors Saravanos, D.A. og P.R.Heyliger, 1995, "Coupled Layerwise Analysis of Composite Beams with Embedded Piezoelectric Sensors and Actuators," Journal of Intelligent Material Systems and Structures, Vol.6 (3), s.350-363. Tzou, H.S., og C.I.Tseng, 1990, "Distributed Piezoelectric Sensor/Actuator Design for Dynamic Measurement/Control of Distributed Parameter Systems - A Piezoelectric Finite Element Approach," Journal of Sound and Vibration, Vol.138 (1), s.17 -34. So far, numerous research activities on the vibration suppression of the feed system have been undertaken. However, the study on the dynamic characteristics of the CD-ROM drive base is considerably rare. Figures 5 and 6 present the measured piezoelectric shunt damping performance for two target frequencies in the frequency and time domain. Vibration reduction by the piezoelectric shunt damping is expected to significantly improve the performance of the CD-ROM drive. The generalized electromechanical coupling coefficient of the proposed shunt system is used as one of the main modal parameters. Furthermore, since the desired design objective of the optimal design is to maximize the shunting damping performance with minimal variation in the dynamic drive characteristics, the vector of modal parameters is chosen by . Z ǻȟ However, the experimental results show that the shunt damping using the proposed piezoelectric bimorph can be effectively applied to the vibration suppression of HDD disk-spindle system. Measured frequency responses of the drive shaft system using piezoelectric damping (impact point, measurement point). J., (1996), Multimode Passive Vibration Suppression with Piezoelectric Materials and Resonant Shunts, Journal of Intelligent Material Systems and Structures, 5, 49-57. W., (2001), Active-Passive Hybrid Piezoelectric Networks for Vibration Control: Comparison and Improvement, Smart Materials and Structures. P ROGRESS IN S TRUCTURAL H EALTH M ONITORING AND N ON - DESTRUCTIVE E VALUATION U SING P IEZO - IMPEDANCE T RANSDUCERS The recent developments facilitate a much broader and more meaningful application of the EMI technique for SHM/NDE of a wide spectrum of structural systems ranging from aerospace components to civil structures. In principle, this technique is comparable to the global dynamic techniques, but the sensitivity is of the order of the local ultrasonic techniques. Similarly, H33T H33T (1 G j) is the complex electrical permittivity of the PZT material at zero voltage, G is the dielectric loss factor. Similarly, electrical loss is caused by the phase lag of the electrical displacement behind the electric field. 4), the magnitude of the force in the PZT patch (or structure) can be calculated as Feq KSlSeq. Furthermore, the mechanical impedance Z of the structure is by definition related to the axial force F in the PZT patch at . The electromechanical admittance of the entire PZT patch can be obtained simply by multiplying the above expression by a factor of 2.4, which shows the effect of damage on the conductance signature of a PZT patch bonded on a steel beam. As such, Zhou et al. cannot be used to experimentally determine the mechanical impedance of the drive point. To alleviate the shortcomings inherent in existing models, Bhalla and Soh (2004b) proposed a new PZT-structure interaction model based on the concept of 'effective impedance'. The effective driving point (EDP) impedance of the host structure can also be defined along similar lines. The overall planar force (or the effective force), F, is related to the EDP impedance of the host structure by.
5 Conclusions
V IBRATION C ONTROL OF CD-ROM AND HDD S YSTEMS U SING P IEZOELECTRIC S HUNT C IRCUITS
2 CD-ROM Drive Base 2.1 Admittance Analysis
Shunt Performance
3 HDD Disk-Spindle System 3.1 Shunt Circuit Design
Sensitivity Analysis
Z ǻȥ
Shunt Performance
4 Conclusion
Introduction
Piezoelectric Constitutive Relations
Existing PZT-Structure Interaction Models
1sin1
Effective Mechanical Impedance and Associated Modelling
