PSI - Issue 64

Rui-Xin Jia et al. / Procedia Structural Integrity 64 (2024) 799–806 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

802

4

2000mm

1500mm

Pressure sensor

Receiving sensor

Nut Excitation sensor

Rebar

Jack

Load system

Signal Excitation and Acquisition System

Fig. 2 Layout of the experimental system

Table. 1. Rebar material parameters Material parameters

Value

Material parameters

Value 314.5

Cross-section area /mm 2

Modulus of elasticity E /GPa

208

Density ρ /kg·m -3 Poisson's ratio v

7800

Yield strength /MPa

500 157

0.3

Yield force /kN

3.2. Measurement of first wave speed According to the above, the cylindrical group velocity dispersion curve has a single mode for the guided wave within 150 kHz. The guided wave excitation signal is selected as a 5-cycle sinusoidal signal through the Hanning window with center frequencies of 50 kHZ, 75 kHZ and 100 kHZ. The first wave speed is measured using the time of arrival of the first wave crest as received by the sensors at the different locations mentioned above. The received signals were acquired through an acoustic emission system with a sampling rate of 1MHz.The received signal carries the noise signal generated by the device, which is filtered and processed for noise reduction using a low-pass filter. The received waveforms after processing are shown in Fig.3 and 4.

(a) 0kN force

(b) 140kN force

Fig. 3 The signal received by the excitation sensor

(a) 0kN force

(b) 140kN force

Fig. 4 The signal received by the receiving sensor

4. Analysis of results 4.1. Bare rebar experimental results

The first wave speeds are calculated for different tension forces and the results are shown in Table.2. From the table, it can be seen that at the same tension, the first wave speed decreases with the increase of frequency. It can