Lead zirconate titanate (PZT) based impedance transducers have been widely used in structural health monitoring (SHM).
They have shown excellent capabilities in evaluation of structural health in terms of damage, deformation and load
monitoring. However, in applications of large scale structures or in the case that structure to be monitored is difficult to
access, the accuracy of data acquired is compromised due to long cables used to connect sensors and data acquisition
equipment. Wireless technology is therefore desired in controlling health monitoring of aerospace, civil and mechanical
structures to solve the problem. This paper presents a newly developed wireless impedance analyzer which is applied to
monitor structural damage. The reliability of the wireless data acquisition system is analyzed by comparing signatures
acquired using wireless impedance analyzer against those obtained from traditional cable connection.
Recent advances in fibre Bragg grating (FBG) and piezoceramic lead zirconate titanate (PZT) sensors have enhanced
their applicability in structural health monitoring (SHM). FBG belongs to fine class of fibre optical sensors which are
extensively used in noise and vibration control and SHM of engineering structures. FBG sensors utilize intensity
modulation or phase modulation techniques for sensing. On the other hand, PZT impedance sensors work on the
principle of electromechanical impedance (EMI). In the EMI technique, PZT works as both sensor and actuator. When
an electric field is applied on PZT, it vibrates the local area of the structure where the PZT is bonded. These vibrations
are then captured by the sensing capability of PZT in terms of EMI signatures. The present paper examines the
combination of FBG and PZT sensors for load monitoring. A number of FBG and PZT sensors are experimentally tested
for load monitoring on various metallic specimens. The two types of sensor were bonded to a protective mounting
instead of being directly bonded to host structure such that they can be removed after test and used for future application.
The results are compared using statistical indices like root mean square deviation index.
Lead Zirconate Titanate (PZT) transducers have been extensively used in the electromechanical impedance (EMI) based
structural health monitoring (SHM). Many EMI models have been developed for damage assessment, mostly focusing
on single damage identification. However, in real life, structures are frequently subjected to multiple or progressive
damages. Specifically, structural components such as beams and columns are subjected to loading, vibration, wear and
tear which could cause multiple damages. Once damages occur, they usually propagate along certain directions due to
continuous usage or inadequate protection. Moreover the increase in severity of damages may lead to failure of the
structural components or even the whole structure. The EMI technique which is based on the electromechanical
interaction between the PZT transducer and its host structure has been found to be effective in damage detection.
However, systematic study on monitoring the progressive of damage in multiple directions in the structures is still in
need. In this paper, the EMI technique using surface bonded PZT transducers is employed to obtain the structural health
signature. Experimental tests are carried out to study the damage propagation on aluminum plates, where damages are
created along the length and width directions of the plates by drilling holes in sequence. Structural health signatures are
obtained for each damage state and compared with the signature of non-damage state, followed by the discussion on the
characteristics of damage propagation. In addition, for different damaged states, finite element modeling is carried out to
verify the experimental signatures. The acquired numerical results are analyzed both qualitatively and quantitatively.
Both experimental and numerical results demonstrate the capability of EMI technique for damage propagation