|
Semi-active vibration control using piezoelectric actuators in smart structures
Jinhao QIU, Hongli JI, Kongjun ZHU
Front Mech Eng Chin. 2009, 4 (3): 242-251.
https://doi.org/10.1007/s11465-009-0068-z
The piezoelectric materials, as the most widely used functional materials in smart structures, have many outstanding advantages for sensors and actuators, especially in vibration control, because of their excellent mechanical-electrical coupling characteristics and frequency response characteristics. Semi-active vibration control based on state switching and pulse switching has been receiving much attention over the past decade because of several advantages. Compared with standard passive piezoelectric damping, these new semi-passive techniques offer higher robustness. Compared with active damping systems, their implementation does not require any sophisticated signal processing systems or any bulky power amplifier. In this review article, the principles of the semi-active control methods based on switched shunt circuit, including state-switched method, synchronized switch damping techniques, and active control theory-based switching techniques, and their recent developments are introduced. Moreover, the future directions of research in semi-active control are also summarized.
Figures and Tables |
References |
Related Articles |
Metrics
|
|
Integrated design of legged mechatronic system
Chin-Yin CHEN, I-Ming CHEN, Chi-Cheng CHENG
Front Mech Eng Chin. 2009, 4 (3): 264-275.
https://doi.org/10.1007/s11465-009-0060-7
This paper presents a system based on the integrated design and experiment for a one degree-of-freedom (DOF) legged mechatronic system (LMTS). A six-bar linkage mechanism, which is derived from a four-bar linkage with a symmetrical coupler point and pantograph into one, is designed, and common controllers are used to control the velocity and position loops. For system-based dynamic optimization, the design for control (DFC) approach is used to integrate the structure and control for improving dynamic performance with reduced control torque. Finally, for a rapid 3D graphical based implementation of the system, high-level computer-aided rapid system integration (CARSI) technology is used to integrate the structure design, controller design, and system implementation into the design and analytical software environment based on Pro/engineer, XML syntax, Simmechanics, and Simulink. Thus, the development time for the LMTS is reduced.
Figures and Tables |
References |
Related Articles |
Metrics
|
|
Identification of dynamic stiffness matrix of bearing joint region
Feng HU, Bo WU, Youmin HU, Tielin SHI
Front Mech Eng Chin. 2009, 4 (3): 289-299.
https://doi.org/10.1007/s11465-009-0064-3
The paper proposes an identification method of the dynamic stiffness matrix of a bearing joint region on the basis of theoretical analysis and experiments. The author deduces an identification model of the dynamic stiffness matrix from the synthetic substructure method. The dynamic stiffness matrix of the bearing joint region can be identified by measuring the matrix of frequency response function (FRFs) of the substructure (axle) and whole structure (assembly of the axle, bearing, and bearing housing) in different positions. Considering difficulty in measuring angular displacement, applying moment, and directly measuring relevant FRFs of rotational degree of freedom, the author employs an accurately calibrated finite element model of the unconstrained structure for indirect estimation. With experiments and simulation analysis, FRFs related with translational degree of freedom, which is estimated through the finite element model, agrees with experimental results, and there is very high reliability in the identified dynamic stiffness matrix of the bearing joint region.
Figures and Tables |
References |
Related Articles |
Metrics
|
|
Monitoring corrosion of reinforcement in concrete structures via fiber Bragg grating sensors
Zhupeng ZHENG, Xiaoning SUN, Ying LEI
Front Mech Eng Chin. 2009, 4 (3): 316-319.
https://doi.org/10.1007/s11465-009-0040-y
Corrosion of steel and rebar in concrete structures is one of the most frequent reasons for civil infrastructure failures. Thus, improving the effective corrosion sensor technology can greatly reduce cost and provide safe structures with long service lives. However, assessing the corrosion condition of rebars is not simple because they are buried in concrete. In this paper, using fiber Bragg grating (FBG), a corrosion sensor for monitoring steel rebars embedded in a concrete structure is developed and validated by experiments. Based on the fact that the volume and diameter of a rebar embedded in concrete will enlarge due to corrosion, an FBG packaged with fiber-reinforced plastics (FRP) is wrapped on the steel bar. During corrosion, the increase in the bar diameter leads to the increase in fiber strain, which can be measured by the shift of the wavelength of FBG. Performances of the corrosion sensor are validated by accelerating corrosion in lab experiments. The corrosion sensor is embedded in a concrete specimen put in a 5% sodium chloride solution with a constant current. Experimental results show that the corrosion sensor can monitor the concurrence of corrosion of rebars in concrete. The corrosion extent can be quantitatively evaluated through the change in the wavelength of FBG. Therefore, the corrosion sensor developed in this paper is feasible for monitoring the early corrosion of rebars in concrete.
Figures and Tables |
References |
Related Articles |
Metrics
|
|
Microstructure and electrical properties of NaNbO3-BaTiO3 lead-free piezoelectric ceramics
Shihui XIE, Kongjun ZHU, Jinhao QIU, Hua GUO
Front Mech Eng Chin. 2009, 4 (3): 345-349.
https://doi.org/10.1007/s11465-009-0050-9
Lead-free piezoelectric ceramics (1-x)NaNbO3-xBaTiO3 have been fabricated by a traditional ceramic sintering technique. The effects of BaTiO3 (BT) synthesized by hydrothermal method on crystal structure, density, dielectric, piezoelectric, and electromechanical properties were investigated. Results show that the phase structure transforms from the orthorhombic phase to the tetragonal phase with the increase of the content of BT, and the two phases co-exist when 0.08<x≤0.10. However, the optimum composition for (1-x)NaNbO3-xBaTiO3 ceramics is 0.90NaNbO3-0.10BaTiO3. The 0.90NaNbO3-0.10BaTiO3 ceramics sintered at 1250°C have higher properties: piezoelectric constant d33 of 120 pC/N, dielectric constant ?r of 718, planar electromechanical coupling factor kp of 24%, planar frequency Nd of 3 MHz·mm, and the mechanical quality factor Qm of 138, respectively. The results show that the (1-x)NaNbO3-xBaTiO3 ceramics is one of the promising lead-free materials for high-frequency applications.
Figures and Tables |
References |
Related Articles |
Metrics
|
|
Polymer nanocomposites for microactuation and magneto-electric transduction
Kaori YUSE, Benoit GUIFFARD, Rabah BELOUADAH, Lionel PETIT, Laurence SEVEYRAT,, Daniel GUYOMAR
Front Mech Eng Chin. 2009, 4 (3): 350-354.
https://doi.org/10.1007/s11465-009-0056-3
In the last decade, electroactive polymers have attracted much attention especially because of their very actuating capabilities. Large strain is experimentally observed, but under quite high electrical field, which can be a severe drawback for actuating applications. First part of the present paper is concerned with the reduction of applied field onto electroactive polymer films to get a given strain level. Polyurethane (PU) films filled with carbon black (CB) nanoparticles exhibit relatively high strain level under a field of only 12.5 kV/mm. The simple easy-to-make method solution cast method was applied. Even though the generated stress level is still quite low, the present work shows high strain level under quite low field appliance by easy manufacturing, lightweight, and flexible polymer film. Besides, another interest of the present paper is in magneto-elasto-electric effect of a polymer film filled with some magnetic nano particles. Films filled with nonpiezoelectric but with magnetite particles has still short history. With the use of magneto materials, a large magnetic DC bias field is generally required, and it causes big problem on application. The films filled with some magnetite nanoparticles (Fe3O4 and Nickel) are fabricated then examined. It is clearly demonstrated that our films do not require any DC bias. Although linear polarization value is relatively small, the first step of the studies on magnetite nano-filled film is presented.
Figures and Tables |
References |
Related Articles |
Metrics
|
17 articles
|