The sensitivity of the technique is important to know how to identify the appearance of cracks
The term 'sensitivity' has wide range of meaning. For impedance-SHM, it is defined as the capacity to show effective deviation in measured parameter relative to change in physical properties of substrate/host. You can go through my 'Measurement' papers to know more about calculating sensitivity of impedance-based SHM for identifying concrete beam crack.
The term 'sensitivity' has wide range of meaning. For impedance-SHM, it is defined as the capacity to show effective deviation in measured parameter relative to change in physical properties of substrate/host. You can go through my 'Measurement' papers to know more about calculating sensitivity of impedance-based SHM for identifying concrete beam crack.
Thank you, Moin Ul Haq . I would like to better understand the sensitivity of the SHM technique, observing the resistive impedance of the structure as a function of frequency. Understand the changes in the signal that a crack, originating from a concrete beam in continuous operation, causes.
If possible, I would like you to share me your publications on this subject.
Dear Philippe César Fernandes Teixeira, the electrical impedance (EI) measurements obtained from PZT gives the information about the local state of the material. The changes in concrete, within the zone of influence of PZT, reflects in the measured EI response.
According to my research, the EI measurements are sensitive to the distributed damage present within the zone of influence of PZT. If the cracking in concrete is localized (single dominant crack), then the EI measurements are not very sensitive, even if the crack is located within the zone of influence. But the interesting study can be finding the distance between PZT and localized cracking in concrete (along with characteristics of the crack) so that it can sensitively be detected in EI measurements.
I provided the links for the zone of influence of the PZT, the response of PZT to the localized cracking in concrete, and the response of the PZT to the distributed damage in concrete below:
Article Understanding the Coupled Electromechanical Response of a PZ...
Article PZT Sensor Array for Local and Distributed Measurements of L...
Article Embedded Smart PZT-based Sensor for Internal Damage Detectio...
Article Experimental evaluation of load-induced damage in concrete f...
Dear Philippe,
From the research I have conducted on this topic, it is evident the sensitivity of the EMI technique is strongly dependant on the hosting material, or if you wish to say the monitored material mechanical properties and especially the damping properties of the material. If we defined the ' sensitivity term' as the distance in which the admittance response generated from the piezo material renders sensitivity to the mechanical changes, and by considering localized damage, this distance is greatly varying from steel to timber to concrete due to the difference in their damping properties. Also, the type and the piezoelectric specifications of the used trancducer play a role in the sensitivity of the technique.
Here is a link to a paper our research group has published about the sensitivity of the EMI technique to localized damage in cementitious mortars through both damage and repair, hopefully, it helps!
https://www.mdpi.com/582758
Dear Philippe César Fernandes Teixeira ,
yes, the EI measurements do depend on the stiffness of the medium, damping of the medium, Poisson's ratio of the medium, size of the medium, the excitation energy of PZT, frequency of excitation of the PZT, as Hussameldin Taha pointed out. The zone of influence of the PZT does depend on all these factors.
In my previous answer, I am purely talking about the distance between PZT and localized cracking from the point of view of matured concrete (assuming the properties of matured concrete remains more or less constant).
Thank you,
K Amarteja
Amarteja Kocherla and Hussameldin Taha Thanks for the contributions. It will certainly contribute a lot to the evolution of my research.
Dear Philippe,
Electro-mechanical impedance technique using peizo sensors uses ultra sonic frequencies because of which the sensitivity is very local as the modes of vibration are local modes. This technique is very sensitive to incipient damages
I partially agree with Dr. Visalakshi. It may be difficult to capture local modes, whose participation in the global response will be too small (hope, I am not wrong). Appropriate filtering techniques may be needed to identify those modes. Further, a base line data is needed, to compare pre and post damage data.
- Badges
- Science topic