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In the last few decades, piezoceramic (PZT) transducers have been extensively used either as actuators or as sensors in the vibration and noise control of aero, civil, and mechanical (ACM) systems. Only in the last decade, PZT transducers have been used in the electromechanical impedance (EMI) models as both sensor and actuator for the structural health monitoring of ACM systems. In the EMI models, the PZT transducers are generally surface bonded to the host structure and are then subjected to one-dimensional (ID) voltage to interrogate the structure for the desired frequency range. The interrogation results in the prediction of electromechanical admittance signatures. These signatures serve as indicators of the health/ integrity of the structure. However, the existing single PZT--structure interaction models consider the PZT transducer to be negligible in mass and thus ignored. Moreover, they impose restrictions on the PZT shape, size, and isotropy. This paper presents it novel semianalytical multiple three-dimensional PZT--structure interaction model which considers the 'mass' of the PZT transducers, and the transducers are subjected to parallel (1D) sinusoidal voltage. Further, the model does not impose restriction on the shape (square or rectangular), size (thin or thick), and electrical properties (isotropic or anisotropic) of PZT. The derived model is also experimentally verified using lab-sized aluminum plate. As it is generic, the model is expected to be applicable for the nondestructive evaluation of most ACM systems. DOI: 10.1061/(ASCE)0893-1321(2008)21:1(35) CE Database subject headings: Three-dimensional models; Vibration; Noise control; Sensors; Nondestructive tests.

Piezoceramic transducers (PZTs) are extensively used in vibration and noise control, and damage detection of various engineering structures. In the last decade, its application has been extended to include their interactions with the host structure in electromechanical impedance models. The interaction between the host structure and PZT is governed by both the extensional and longitudinal vibrations of the transducer. However, the interaction models developed in the last decade consider only the one-dimension or two-dimension extensional actuations, ignoring the longitudinal actuations. This study examines the three-dimensional (3D) interaction of a transducer with the host structure, considering both the extensional and the longitudinal actuations of the transducer. It does not impose any restriction on the shape, size, and electrical properties of the PZT and thus contains additional features over the existing PZT-structure interaction models. This paper is Part I of a two-part paper, which presents a new 'directional sum' numerical-analytical admittance formulation with experimental verification. Part II of this paper will elaborate on the damage analysis and characterization of PZT properties for the new 3D model. DOI: 10.1061/(ASCE)0893-1321(2007)20:1(53) CE Database subject headings: Structural reliability; Monitoring; Three-dimensional models; Damage.

Piezoceramic transducers (PZTs) are extensively used in the nondestructive evaluation of damages in various engineering structures. This paper, the second of a two-part paper, focuses on the application of a PZT using three-dimensional (3D) directional sum impedance (DSI). The semianalytical 3D admittance has been formulated and experimentally validated in the first paper. This part deals with the application of the 3D DSI model in damage analysis where by damages were numerically simulated for various types of specimens and the DSI admittance signatures were predicted and compared. The deviations of the signature from that of the undamaged state provide an indicator for the health of the structure. This technique is nondestructive in nature, and the damages were quantified using root-mean-square deviation in signatures with respect to the undamaged state signature. In Part I, the properties of the PZT and their influences on admittance signatures were briefly presented. In this part, a thorough investigation was made and the importance of all the PZT properties in damage analysis was presented. DOI: 10.1061/(ASCE)0893-1321(2007)20:1(63) CE Database subject headings: Structural reliability; Monitoring; Three-dimensional models; Damage.

Asia is the largest and most populous continent in the world with over 45 million square kilometers of land mass and 4.5 billion people. Asia is characterized by numerous densely populated cities. Structural health monitoring is a non-issue for the underdeveloped countries where basic amenities of survival are more important. However, structural health monitoring is crucial for the developing countries, especially those with densely populated cities like Singapore, Mumbai, and Hong Kong, where any infrastructural failure could be devastating to their society and economy. Structural health monitoring of mechanical and aerospace structures is mostly similar worldwide, but of civil infrastructures could vary due to socio-economic, cultural, geographical, and governmental reasons across countries, and even across states within the same country. This article, which is an enhancement to the keynote paper of the International Workshop on Structural Health Monitoring (IWSHM 2015, Stanford University, USA), presents some of the better known structural health monitoring studies of key civil infrastructures in a few Asian countries. In addition, the authors’ research and applications of structural health monitoring technology carried out at the Nanyang Technological University for civil infrastructures in Singapore are presented. At the end, the authors also discuss recent work on energy harvesting using piezoelectric transducers as an alternative to wired structural health monitoring for automated and self-powered structural health monitoring. [ABSTRACT FROM AUTHOR]

The recent advent of highly durable engineering materials and the advancement of latest structural design theories have made possible the fabrication of more efficient engineering structures. However, the safety and reliability of these structures remains the primary challenge and concern for engineers. Especially, for those structures which involve human traffic and huge investments such as the aerospace structures and bridges. Therefore, there is a compelling need to have high-quality online structural health monitoring (SHM) of such structures. The development of a real-time, in-service, and smart material-based SHM method has recently attracted the interest of a large number of academic and industrial researchers. In the recent past, piezoceramic (PZT) transducer has evolved as an efficient smart material, which is usually employed in electro mechanical impedance (EMI) and guided ultrasonic wave propagation techniques. In EMI technique, a PZT transducer interact with the host structure to result in unique health signature, as an inverse function of structural impedance, when it is subjected to high-frequency structural excitations in the presence of electric field. Using the self-actuating and sensing capabilities of PZT transducers, the EMI models attempted to detect loadings on, and damages in, the structures to be monitored. This article reviews some of the advancements in the field of PZT-based SHM made over the past two decades in engineering structures. This article also provides an insight into the possible future work and improvements required for PZT-based EMI technique. [ABSTRACT FROM AUTHOR]