PSI - Issue 64

Alamgir Khan et al. / Procedia Structural Integrity 64 (2024) 539–548 Alamgir khan / Structural Integrity Procedia 00 (2019) 000–000

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3.2 Piezoresistivity investigation at room temperature Fig. 3 (a-d) illustrates the frictional changes in the electrical resistivity, repeatability, and strain sensitivity correlation of the CNCB1-CNCB2, under cyclic compression loading at room temperature. The FCR response of CNCB1-CNCB2, was investigated for five repeatable cyclic compression loadings at amplitudes of 10, 15, and 20 kN. The overall FCR mechanism trend was the same for CNCB1-CNCB2 at different loading amplitudes; as the load/strain increased, the FCR decreased, and the load/strain decreased the FCR. The FCR response of CNCB1 decreased as the load/strain increases from 10-20kN amplitudes by 13%, 14%, and 16%, corresponding to different cyclic compression loading amplitudes. CNCB2 exhibited a high load/strain sensitivity and a high FCR response of 25%, 30%, and 33%, under 10-20 kN, owing to the high number and closer MWCNT/NCB composite filler conductive paths, which greatly improved the FCR response and reversibility.

(b) CNCB1

(a) CNCB1

10 15 20

Strain FCR

Load FCR

2E−2

10 15 20

20

Loading Unloading

1E−2

10

0 5

0 5

0E+0

0

Strain

−1E−2

−20 −15 −10 −5

-20 -15 -10 -5

FCR (%)

FCR (%)

-10 Load (kN)

−2E−2

-20

Decreasing FCR Increasing FCR

−3E−2

0 100 200 300 400 500 600 700 800 900 -30

0 100 200 300 400 500 600 700 800 900

Time (s)

Time (s)

40

40

(c) CNCB2

(d) CNCB2

Strain FCR

Load FCR

3E-2

30

30

20

2E-2

20

20

10

1E-2

10

10

0

0

0E+0

0

Strain

-10

-10

-1E-2

FCR (%)

FCR (%)

-10 Load (kN)

-20

-20

-2E-2

-20

-30

-30

-3E-2

-40

0 100 200 300 400 500 600 700 800 900 -30

-40

0 100 200 300 400 500 600 700 800 900

Time (s)

Time (s)

Fig. 3 Piezoresistivity of MWCNT/NCB composite fillers at room temperature

3.3 Piezoresistivity investigation at 200 ˚ C temperature The variations in the electrical resistivities of CNCB1 and CNCB2 after exposure to an elevated temperature of 200 °C are shown in Fig. 4 (a-d). After exposure to CNCB1 and CNCB2, their peak FCR responses corresponded to