**2.4 Acoustic emission system**

This system includes an acoustic emission sensor, a preamplifier, and acoustic emission software. The acoustic emission sensor used in this test is made of Lead-Zirconate with a diameter of 5 mm and a height of 4 mm of broad-band type and is connected to the preamplifier via a cable. The preamplifier has an input that can gain the signal received from the acoustic emission sensor with coefficients of 20, 40, and 60 dB. In this test, a coefficient of 40 dB was used and the output part sends the signal by cable to the computer for processing. The software installed on the computer is called AEwin for PCI-2, which allows us to set the parameters of acoustic emission testing, interpretation, display, and analysis of waveforms, adjust and display and compare several graphs, etc. [9]. **Figure 6** shows the schematic of acoustic emission system. After plotting various diagrams such as acoustic emission

**Figure 5.** *Schematic and component of tensile machine.*

**Figure 6.** *Schematic of acoustic emission system.*

signal amplitude vs. standard cycle diagram and acoustic emission cumulative count vs. standard cycle diagram by the acoustic emission system, and by analyzing the acoustic emission parameters such as signal amplitude, counts, rise time and duration time (In this test, acoustic emission amplitude and count were used), the crack initiation and crack growth can be determined.

The threshold was determined based on ambient noise in the bending fatigue test of 45 dB and in the tensile test of 20 dB, the frequency between 20 kHz to 1 MHz and the sampling rate of 2 MHz per second were determined in acoustic emission software.
