Prognosis of fatigue and impact induced damage in concrete using embedded piezo-transducers – sciencedirect natural electricity examples

Concrete structures are often subjected to a wide array of load conditions, such as fatigue and impact, and the consequent damages. Recently, smart materials, in particular the piezoelectric materials, have received high attention from the point of view of structural health monitoring (SHM). In this connection, the electro-mechanical impedance (EMI) is one of the latest and most effective techniques. The technique harnesses the piezoelectric property of lead-zirconate-titanate (PZT) patches to sense any incipient damage. In the research covered in the paper, embedded PZT patches are employed to monitor the accumulating damage in plain cement concrete subjected to fatigue and impact type loadings. Concrete specimens (150 mm cubes and 100φ × 200 mm cylinders) of grade M-25 are cast with embedded concrete vibration sensors (CVS). The impact loading is simulated by a free falling iron-ball of mass 5 kg dropped from variable heights of 2 m, 2.5 m and 3 m above the top surface of the test cubes. For fatigue tests, a 4000 kN cyclic compression testing machine is used to apply the fatigue load in a sinusoidal form. The admittance signatures from the embedded PZT patches for impact and fatigue tests are acquired using an LCR meter. These signatures are used to determine the PZT-identified equivalent system properties (damping, stiffness and mass) of the specimens at varying damage states. For impact tests, strain history during the impact process is acquired in addition to the admittance signatures. The results for impact tests show an increase in the maximum strain induced in the patch with the number of impacts, while the equivalent damping computed from the admittance signature is found to decrease with increasing damage. For fatigue tests, the equivalent damping is again found to decrease with increasing damage, finally undergoing a phenomenal increase near the failure. Based on these measurements, separate relationships have been developed for impact and fatigue induced damages linking the PZT-identified damping with remaining life.

Mr. Anjaneya Dixit is currently a Research Scholar in the Department of Civil and Environmental Engineering, National University of Singapore. Mr. Dixit completed his Bachelor of Technology in Civil Engineering from the Indian Institute of Technology (IIT)-BHU, Varanasi in 2011. Before obtaining his Masters in Structural Engineering from IIT-Delhi in 2016, Mr. Dixit worked as an ‘Engineer’ in the ‘Bharat Heavy Electricals Limited’ (a Govt. of India undertaking) between 2011–2014. His main areas of interest are smart structures, structural health monitoring, electro-mechanical impedance (EMI) technique, energy efficient buildings, phase change materials and ultra-high performance concrete. Mr. Dixit has been the recipient of the 2nd Best Paper award at the ‘2nd International Conference on Fatigue, Durability and Fracture Mechanics, Bangalore (2016)’, the ‘Silver Medal’ awarded by the Dept. of Civil Engineering, IIT-BHU (2011) and ‘Certificate of merit’ for outstanding academic performance (2009 and 2010).

Dr. Suresh Bhalla is currently Professor at the Department of Civil Engineering, IIT Delhi. His main areas of interest are smart structures, structural health monitoring, electro-mechanical impedance (EMI) technique, bio-mechanics/ bio-medical applications of smart materials, piezoelectric energy harvesting and engineered bamboo structures. Dr. Bhalla has been the founder of the “Smart Structures and Dynamics Lab” at IIT Delhi. Dr. Bhalla has published over 50 papers in international journals, and over 70 in international/ national refereed conferences/ workshops. He has co-authored two books “Smart Materials in Structural Health Monitoring, Control and Bio-mechanics (Springer)” and “Piezoelectric Materials: Applications in SHM, Energy Harvesting and Bio-mechanics (Wiley)”. He has also contributed chapters for three other books. A finalist of the SCOPUS Young Scientist Award 2014, Dr. Bhalla has been the recipient of several other laurels, such as the award for teaching excellence (2011), outstanding young faculty fellow (2008), NSTB gold medal for best Master’s thesis (2001) and the Institute silver medal (1995). Dr. Bhalla has four invention disclosures to his credit, three of which have been applied for patent.