Review of State of Art of Smart Structures and Integrated Systems

Review of state of the art in smart rotor control research for wind turbines

The growth of piezo science is phenomenal since the discovery of piezoelectricity in 1880. Among various piezoelectric materials, lead zirconate titanate (PZT) is a very popular and exhaustively studied piezo system which allows synthesis of large number of materials with wide range of properties due to formation of solid solutions over large range of Zr:Ti ratio. Also, this system accommodates wide range of dopants for modification of crystal structure. Due to this versatile nature, PZT has emerged as very popular among users and researchers worldwide. However, considering the toxicity of lead oxide, development of lead free piezo ceramics is encouraged in recent years. Some lead free piezo material systems such as BNT, BKT, KNN, BZT-BCT have been explored. However, development of lead free piezo devices and their performance in comparison with PZT devices are yet to be established. At this juncture, it was felt that an article reviewing the current status of development of piezo materials highlighting t...

PZT to Lead Free Piezo Ceramics: A Review

This article presents in a unified way, the various optimization criteria used by researchers for optimal placement of piezoelectric sensors and actuators on a smart structure. The article discusses optimal placement of piezoelectric sensors and actuators based upon six criteria: (i) maximizing modal forces/moments applied by piezoelectric actuators, (ii) maximizing deflection of the host structure, (iii) minimizing control effort/maximizing energy dissipated, (iv) maximizing degree of controllability, (v) maximizing degree of observability, and (vi) minimizing spill-over effects. Optimal piezoelectric sensor and actuator locations on beam and plate structures for each criterion and modes of interest are presented in a tabular form. This technical review has two objectives: (i) practicing engineers can pick the most suitable philosophy for their end application and (ii) researchers can come to know about potential gaps in this area.

Optimization Criteria for Optimal Placement of Piezoelectric Sensors and Actuators on a Smart Structure: A Technical Review

In this review, recent progress in the mechanical, thermal and interfacial properties of graphene/CNT multiphase polymer composites is examined. Progress in the mechanical and thermal properties of CNT (1D) and graphene (2D) nanostructure materials is also reviewed and compared. Furthermore, this review highlights the improvements in the mechanical, thermal and interfacial properties of two- and three-phase composites, owing to the addition of graphene/CNT. In particular, analysis of several notable papers on hybrid composites (graphene/CNT) provides an intensive review of synergetic effects on the overall properties of the corresponding composites. This holistic review describes an improved interface between fibers and a nanofiller-reinforced matrix. Although the presence of nanofillers even at low loadings confers an overall improvement in composite properties, the exact ratios of individual fillers and combined forms remain to be discussed in depth. Finally, potential applications, current challenges and future perspectives for use of these multiphase composites are discussed with regard to their extraordinary capabilities and promising developments in graphene/CNT family-based composite materials.

Carbon nanotube- and graphene-reinforced multiphase polymeric composites: review on their properties and applications

We have used quasi-static equations of piezoelectricity to derive a finite element formulation capable of modelling two different kinds of piezoelastically induced actuation in an adaptive composite sandwich beam. This formulation is made to couple certain piezoelectric constants to a transverse electric field to develop extension-bending actuation and shear-induced actuation. As an illustration, we present a sandwich model of three sublaminates: face/core/face. We develop a control scheme based on the linear quadratic regulator/independent modal space control (LQR/IMSC) method and use this to estimate the active stiffness and the active damping introduced by shear and extension-bending actuators. To assess the performance of each type of actuator, a dynamic response study is carried out in the modal domain. We observe that the shear actuator is more efficient in actively controlling the vibration than the extension-bending actuator for the same control effort.

http://iopscience.iop.org/article/10.1088/0964-1726/11/1/307/pdf

Active vibration control of composite sandwich beams with piezoelectric extension-bending and shear actuators

Vibro-acoustic response and sound transmission loss analysis of functionally graded plates

Flutter control of a composite plate with piezoelectric multilayered actuators

A coupled piezoelectric field is modelled with an expansion strain in the numerical formulation to analyse piezohygrothermoelastic laminated plates and shells. Finite element actuator and sensor equations are derived using a nine-noded field consistent shallow shell element. Thermally induced vibration control is attempted using piezoelectrically developed active damping. The influence of piezoelectric anisotropy on active damping is evaluated, adopting a simple modelling technique. With 40% reduced actuation capability in the lateral direction, the directionally active lamina is observed to be equally efficient in controlling the vibration. In general, the directionally active lamina is efficient if the primary actuation direction is oriented along the fibre direction or in the direction of bending. The directional actuation appeared to be more effective in the velocity feedback control for cantilevered plates and shells. However, in the simply supported case, a balanced actuation effort is required to provide better controllability, which can be achieved by tailoring the directional actuation. The importance of geometric curvature for the actuator performance is also highlighted.

Thermally induced vibration control of composite plates and shells with piezoelectric active damping

The influence of actuator damage on the performance of closed loop vibration control is numerically evaluated. Debonding is considered a damage mode and finite element procedures are subsequently developed to introduce its effect on system matrices, namely elastic and electro-elastic stiffness. A simple modelling scheme for multiple debonding is proposed, which can also idealize multiple delamination in the host laminate. Debonding in actuators in general has reduced their load carrying appreciably as well as vibration control characteristics. Therefore, incorporating such a damage mode in the control design as an uncertainty parameter would help to realize a damage-tolerant active vibration control system. It is interesting to note that debonding in actuators has influenced both active damping and active stiffening effects.

https://iopscience.iop.org/article/10.1088/0964-1726/16/5/012/pdf

S. Raja

Papers

Active vibration control of composite sandwich beams with piezoelectric extension-bending and shear actuators

Vibro-acoustic response and sound transmission loss analysis of functionally graded plates

Flutter control of a composite plate with piezoelectric multilayered actuators

Thermally induced vibration control of composite plates and shells with piezoelectric active damping

Active vibration control of smart plates with partially debonded multilayered PZT actuators