Optical Extensometer Based on Telecentric Lens and Biaxial Field-of-View Splitting Technique

Sipeng Fu; Junjie Li; Feipeng Zhu

doi:10.3788/LOP230965

Laser & Optoelectronics Progress, Volume. 60, Issue 15, 1512003(2023)

Optical Extensometer Based on Telecentric Lens and Biaxial Field-of-View Splitting Technique

Sipeng Fu, Junjie Li, and Feipeng Zhu^*

Author Affiliations

College of Mechanics and Materials, Hohai University, Nanjing 211100, Jiangsu, China

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Abstract Get PDF(in Chinese)

Figures & Tables(15)

Fig. 1. Schematic diagram of the arrangement of four rhombic prisms

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Fig. 2. Measurement schematic diagram of proposed optical extensometer. (a) Optical arrangement; (b) a recorded image

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Fig. 3. Schematic diagram of gauge-length calibration

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Fig. 4. Physical picture of FOV-splitting device. (a) Side view of FOV-splitting device; (b) front view of FOV-splitting device

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Fig. 5. Physical picture of calibration piece

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Fig. 6. Experimental content. (a) Stainless steel specimen; (b) experimental equipment

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Fig. 7. Strain-time curves of different extensometers. (a) Axial strain-time curve; (b) transverse strain-time curve

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Fig. 8. Strain error between two optical extensometers and strain gauges. (a) Axial strain error; (b) transverse strain error

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Fig. 9. Strain measured by two optical extensometers and strain gauges. (a) Axial strain; (b) transverse strain

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Fig. 10. Strain errors of two optical extensometers. (a) Axial strain error;(b) transverse strain error

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Fig. 11. Comparison of mechanical parameters measured by different optical extensometers. (a) Elastic modulus; (b) Poisson's ratio

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Table 1. Axial calibration parameters
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Table 1. Axial calibration parameters
Parameter FOV₁ FOV₃
Coordinate point A P₁ B C P₃ D
Scale /mm 14.6 13 10.8 10 11.6 13.6
Abscissa /pixel 51 511 1148 1380 1844 2421
Magnification K /（pixel·mm^-1） 288.68 289.16

Table 2. Root mean square error of biaxial optical extensometer in cyclic loading test
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Table 2. Root mean square error of biaxial optical extensometer in cyclic loading test
Root mean square error Group 1 Group 2 Group 3
Axial strain error /με 7.23 7.03 6.25
Transverse strain error /με 7.22 5.36 5.04

Table 3. Root mean square error of biaxial optical extensometer in uniaxial tensile tests
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Table 3. Root mean square error of biaxial optical extensometer in uniaxial tensile tests
Root mean square error Group 1 Group 2 Group 3 Group 4
Axial strain error /με 4.04 3.49 5.02 3.04
Transverse strain error /με 4.17 3.82 5.42 4.13

Table 4. Measurement error of elastic modulus and Poisson's ratio

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Table 4. Measurement error of elastic modulus and Poisson's ratio

Data set	Elastic modulus		Poisson’s ratio
Data set	Conventional optical extensometer	Proposed optical extensometer	Conventional optical extensometer	Proposed optical extensometer
Group 1	5.24	0.56	13.72	1.42
Group 2	9.22	0.62	8.85	0.94
Group 3	9.69	0.39	10.02	2.86
Group 4	6.43	0.07	16.17	0.30
Mean value	7.65	0.41	12.19	1.38

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Sipeng Fu, Junjie Li, Feipeng Zhu. Optical Extensometer Based on Telecentric Lens and Biaxial Field-of-View Splitting Technique[J]. Laser & Optoelectronics Progress, 2023, 60(15): 1512003

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Paper Information

Category: Instrumentation, Measurement and Metrology

Received: Mar. 28, 2023

Accepted: Apr. 20, 2023

Published Online: Aug. 18, 2023

The Author Email: Feipeng Zhu (zhufeipeng@hhu.edu.cn)

DOI:10.3788/LOP230965

Topics

laser devices and laser physics

Lasers and Laser Optics

Laser physics

laser manufacturing

Instrumentation, Measurement and Metrology

Table 1. Axial calibration parameters

Table 1. Axial calibration parameters

Table 2. Root mean square error of biaxial optical extensometer in cyclic loading test

Table 2. Root mean square error of biaxial optical extensometer in cyclic loading test

Table 3. Root mean square error of biaxial optical extensometer in uniaxial tensile tests

Table 3. Root mean square error of biaxial optical extensometer in uniaxial tensile tests

Table 4. Measurement error of elastic modulus and Poisson's ratio

Table 4. Measurement error of elastic modulus and Poisson's ratio