Introduction
Chapter 1: Introduction
1.6 Research motivation and objectives
Suresh Kumar and Ray (2012) developed a three-dimensional model of a sandwich plate integrated with ACLD treatment and studied the performance of vertically/obliquely reinforced 1-3 PFC as the material of active constraining layer.
Li and Narita (2013) presented the ACLD treatment of laminated composite plates for arbitrary boundary conditions. Zhang and Zheng (2014) studied the partial ACLD treatment of plates by developing a hybrid controller where it is demonstrated that the controller effectively reduces the displacement-amplitude through the combined feed forward and feed backward control actions. Ni et al.
(2013) investigated the active-passive damping in shells of revolution for ACLD treatment according to a specified control strategy and reported that the ACLD treatment is more effective at low frequency of vibration. Aravinda Kumar et al.
(2016) presented nonlinear frequency responses of heated FG plates integrated with the ACLD treatment where the active constraining layer is made of an extension mode 1-3 PFC. By developing a three-dimensional FE model, Kundalwal and Ray (2016) investigated the ACLD treatment of smart fuzzy fiber reinforced composite (FFRC) plates. Li et al. (2016) studied the suppression of random vibration of laminated composite rectangular plates using ACLD treatment and 1-3 PFC for the material of active constraining layer. Lu et al. (2017) presented a theoretical study on the partial ACLD treatment for control of vibration of thin plates at low frequency, and the corresponding observations have also been verified experimentally.
Chapter 1: Introduction
used in micro-valves, micro-pumps, micro-switches, implantable medical devices, oil storage tanks, brake systems of vehicles, airfoil cascades, oceanographic applications, etc. (Bambill et al., 2004; Buffum and Fleeter, 1986; Cao et al., 2001;
Cha et al., 2015; Kim and Ha, 2003; Sergienko et al., 2008; Shi et al., 2017). But, it has been observed that a few studies on the active control of annular/circular plates have been reported in the literature utilizing the monolithic piezoelectric actuators. Moreover, the utilization of any of the available PFCs for active control of annular/circular plates has not yet been addressed in the literature. This may be due to the fact that the principal material coordinate system of the existing PFCs is the rectangular coordinate system, and thus these PFCs may not be well-qualified materials for distributed actuators where the mechanically induced stresses/strains arise in cylindrical coordinates. So, to employ the concept of PFC for efficient control of plane structures of revolution, the microstructure of the PFC is to be designed in the cylindrical coordinates with the special attentions on the flexibility, conformability, magnitudes of piezoelectric coefficients, strain energy density, directional actuation capability and manufacturing difficulties. The research in this line is not yet addressed in the literature. Thus, the primary objective of the present research is identified as the design of extension/shear mode PFCs with 1-3/2-2 connectivity for efficient control of plane structures of revolution like annular/circular plates. As these plates often undergo bending mode of deformation under operation, the primary intent in this design of 1-3/2-2 PFCs is to achieve the in-plane extensional/transverse shear actuation forces in the cylindrical coordinates, and also to utilize these PFCs in an appropriate manner for efficient control of annular/circular plates.
The 1-3/2-2 PFCs are usually comprised of unidirectional continuous piezoelectric fibers with a high fiber-volume fraction. The long, thin and brittle piezoelectric fibers within these PFCs may break during operation under the moderate/large amplitude of vibration or during its integration with the host structure of complex geometry. This breakage of fibers eventually degrades the actuation capability of PFC, and thus the PFCs are generally used in the form of the patch. But, the shortcoming of fiber damage may persist depending on the size of the patch and also on the complexity of geometry of the host structure. An alternative way is to compose the PFC using short piezoelectric fibers retaining their uniform orientation for directional actuation. But, one has to put particular attention in the design of this PFC because of the possibility of degraded actuation
capability due to the use of the short piezoelectric fibers. In view of these practical issues in the design and applications of 1-3/2-2 PFCs, the second objective of the present research is identified as the design of an extension mode short piezoelectric fiber composite (SPFC) in the cylindrical/rectangular coordinates.
For effective control of any mode of vibration of a smart plate, the piezoelectric actuator is generally used in the form of patches. The size and locations of these patches over the plane of the plate are decided by means of an optimal algorithm.
This analytical procedure for determining the appropriate configuration of the patches becomes a little difficult when several modes of vibration of the plate within an operating frequency-domain are to be attenuated effectively. In this issue, the studies have been carried out by several researchers using various optimization algorithms and extension mode piezoelectric actuators (Hwang and Park, 1993;
Hwang et al. 1993; Ramesh Kumar and Narayanan, 2008; Ray, 1998). Further research in this line may be done in the quest of a simple analytical/numerical procedure for configuring the patches in such a manner that all the modes of vibration of the smart plate within an operating frequency-domain can be attenuated efficiently. Also, the same procedure may be extended for the shear mode piezoelectric actuators as this kind of study is not yet available in the literature. Thus, the third objective of this research is decided as the study on configuring the shear mode piezoelectric patches and controller for efficient control of all the bending modes of vibration of a smart annular plate in an operating frequency-domain.
The piezoelectric actuators possess low control capability with reference to the rigidity of the host structure, and this fact often results in their inefficient control activity in attenuation of structural vibration. Owing to this shortcoming, the use of the piezoelectric actuators along with the viscoelastic materials of low stiffness has been suggested by several researchers (Arafa and Baz, 2000a; Arafa and Baz, 2000b; Baz and Ro, 1995; Baz and Tempia, 2004; Gentilman et al., 1994;
Ghoneim, 1993; Ghoneim, 1996; Reader and Sauter, 1993; Shi et al. 2004). In these studies, the piezoelectric actuator is primarily utilized to enhance the viscoelastic damping in a smart structure. In this context, various hybrid damping treatments of structural vibration have been proposed in the literature like Electro- Mechanical Surface Damping (EMSD) (Ghoneim, 1993; Ghoneim, 1996), Conventional Active Piezoelectric-Damping Composite (CAPDC) (Gentilman et al.
1994; Reader and Sauter, 1993), Active Piezoelectric Damping Composite (APDC)
Chapter 1: Introduction
(Arafa and Baz, 2000a; Arafa and Baz, 2000b; Baz and Tempia, 2004), Active Constrained layer damping (ACLD) (Baz and Ro, 1995; Shi et al., 2004), etc. Among these hybrid damping treatments, the ACLD treatment has gained its credential to become the most efficient means of exploiting the piezoelectric materials for achieving active control of thin-walled structures. Extensive research on the ACLD treatment of structural vibration has been reported in the literature. But, all these studies have been carried out by taking the extension mode piezoelectric actuators.
Since no report on the use of shear mode piezoelectric actuator in the ACLD treatment is available in the literature, one more objective of this research is chosen as the performance of the presently designed shear mode PFC actuator in the ACLD treatment of vibration of annular plates.
In order to fulfill the aforesaid objectives in this research, the following theoretical studies have been carried out:
(a) Design of an extension mode short piezoelectric fiber composite actuator in cylindrical/rectangular coordinates.
(b) Control capability of an extension mode short piezoelectric fiber composite (SPFC) actuator in cylindrical/rectangular coordinates.
(c) A comparative study on the smart damping-capabilities of cylindrically orthotropic piezoelectric fiber composite actuators in vibration control of annular plates.
(d) An annular PFC actuator for shear mode piezoelectric actuation of plane structures of revolution.
(e) Active control of vibration of annular plates using a new shear mode PFC actuator with cylindrically periodic microstructure.
(f) Active-passive damping characteristics of a smart annular sandwich plate using a new shear mode PFC actuator.