PSI - Issue 58

K N Pandey et al. / Procedia Structural Integrity 58 (2024) 122–129 K. N. Pandey and G. Singh / Structural Integrity Procedia 00 (2019) 000–000

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2.2 The Lead Zirconate Titanate (PZT) The piezo-electric sensor used in the present study is lead zirconate titanate (PZT) which acts as a sensor and actuator both and PIC 151 complaint ceramic sensor. These sensors of dimension 10mm×10mm×0.2 mm, were obtained from Central Electronics Limited, Industrial Area, Sahibabad, Uttar Pradesh (India). The physical, electrical, and mechanical properties of PZT sensor are shown in Table 2.

a

b

Fig. 1. (a) Compact Tension (CT) specimen dimensions; (b) CT specimen with surface bonded PZT patch.

The electrodes provided on the top and bottom of the PZT sensor were connected to high voltage and low voltage terminals of the LCR meter for getting signature. The PZT patches were pasted on the specimen near the crack tip by an araldite epoxy but in a way so that it may not damage due to propagation of the crack, Fig. 1 (b) (Soh et al., 2011). 2.3 Experimental procedure Life of a component under random loading conditions can be obtained by converting the random loading into a block loading sequence. In that case the sequence of block load affects the life. Therefore, in the present study sequence such as low-high and high-low are considered. The fatigue tests were conducted on a 25 kN servo-hydraulic test set up of make TWI USA at MNNITA Prayagraj (India). These tests were conducted under load control and 10 Hz frequency. The conductance and susceptance signatures were obtained by stopping the fatigue test at certain cycles of operation and connecting the terminals of the PZT patch pasted on the CT-specimen to a LCR meter of make Hioki (model IM3536) as shown in Fig. 2. The instantaneous length of the crack was measured by a COD gauge. The data acquisition system of the test system collected the instantaneous displacement related data providing the advancement of the crack (Lim and Soh, 2014). The loading conditions for fatigue crack growth tests are given in Table 3.