Juan C. Briñez-de León,1,2,*
Mateo Rico-García,1
and Alejandro Restrepo-Martínez2
1Institución Universitaria Pascual Bravo, Facultad de ingeniería, Departamento de ingeniería electrónica Grupo GIIAM-Calle 73 # 73A, 226, Medellín, Código Postal 050034, Colombia
2Universidad Nacional de Colombia-Sede Medellín-Facultad de Minas, Departamento de Ingeniería Mecánica, Grupo GPIMA-Núcleo el Río, Bloque 04, Carrera 64C No. 63, 120, Medellín, Código Postal 050034, Colombia
Juan C. Briñez-de León, Mateo Rico-García, and Alejandro Restrepo-Martínez, "PhotoelastNet: a deep convolutional neural network for evaluating the stress field by using a single color photoelasticity image," Appl. Opt. 61, D50-D62 (2022)
Quantifying the stress field induced into a piece when it is loaded is important for engineering areas since it allows the possibility to characterize mechanical behaviors and fails caused by stress. For this task, digital photoelasticity has been highlighted by its visual capability of representing the stress information through images with isochromatic fringe patterns. Unfortunately, demodulating such fringes remains a complicated process that, in some cases, depends on several acquisitions, e.g., pixel-by-pixel comparisons, dynamic conditions of load applications, inconsistence corrections, dependence of users, fringe unwrapping processes, etc. Under these drawbacks and taking advantage of the power results reported on deep learning, such as the fringe unwrapping process, this paper develops a deep convolutional neural network for recovering the stress field wrapped into color fringe patterns acquired through digital photoelasticity studies. Our model relies on an untrained convolutional neural network to accurately demodulate the stress maps by inputting only one single photoelasticity image. We demonstrate that the proposed method faithfully recovers the stress field of complex fringe distributions on simulated images with an averaged performance of 92.41% according to the SSIM metric. With this, experimental cases of a disk and ring under compression were evaluated, achieving an averaged performance of 85% in the SSIM metric. These results, on the one hand, are in concordance with new tendencies in the optic community to deal with complicated problems through machine-learning strategies; on the other hand, it creates a new perspective in digital photoelasticity toward demodulating the stress field for a wider quantity of fringe distributions by requiring one single acquisition.
Data underlying the results presented in this paper are not publicly available at this time but may be obtained from the authors upon reasonable request.
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Advantage: Capability of evaluating principal stress difference (isochromatic) with a single polariscope configuration. Non inconsistencies or ambiguities
Disadvantage: Three load movements
Disadvantage: Tuning the load movements that produce appropriate phase shifts. Additional procedures for unwrapping the phase map.
Advantage: Capability of evaluating principal stress difference (isochromatic) with a single polariscope configuration. Non-inconsistencies or ambiguities.
Advantage: Half of the acquisitions compared with initial load stepping method
Disadvantage: Three load movements
Disadvantage: Tuning the load movements that produce appropriate phase shifts. Additional procedures for unwrapping the phase map.
Advantage: Capability of evaluating principal stress difference (isochromatic) with a single polariscope configuration. Non-inconsistencies or ambiguities.
Disadvantage: A color comparison chart is required per every experimental condition, introducing sensibility to experimental variations
Disadvantage: Color search strategies must be included
Advantage: Capability of evaluating principal stress difference (isochromatic) with a single polariscope configuration. Non-inconsistencies or ambiguities.
Disadvantage: A seed point to start must be carefully introduced- Disadvantage: The fringe demodulation is obtaining by solving a cost function per every point
Disadvantage: Color search strategies must be included
Table 2.
Representation of Isochromatic Patterns in the Hybrid Load Stepping Methoda
Representation of a disk observed through a dark field polariscope when $F = 2500N$ load compression, and $\Delta F = 10\% F$.
Table 3.
Photoelasticity Images from a Similar Model but Different Stress Magnitude
Table 4.
Effect of Light Sources Within the Fringe Visualization Processa
Stress maps were normalized with respect to a maximum value of six fringe orders.
Table 5.
Isochromatic Fringes from Applications of Different Engineering Areas
Table 6.
Benchmarks for Experiments in Photoelasticity Studies
Advantage: Capability of evaluating principal stress difference (isochromatic) with a single polariscope configuration. Non inconsistencies or ambiguities
Disadvantage: Three load movements
Disadvantage: Tuning the load movements that produce appropriate phase shifts. Additional procedures for unwrapping the phase map.
Advantage: Capability of evaluating principal stress difference (isochromatic) with a single polariscope configuration. Non-inconsistencies or ambiguities.
Advantage: Half of the acquisitions compared with initial load stepping method
Disadvantage: Three load movements
Disadvantage: Tuning the load movements that produce appropriate phase shifts. Additional procedures for unwrapping the phase map.
Advantage: Capability of evaluating principal stress difference (isochromatic) with a single polariscope configuration. Non-inconsistencies or ambiguities.
Disadvantage: A color comparison chart is required per every experimental condition, introducing sensibility to experimental variations
Disadvantage: Color search strategies must be included
Advantage: Capability of evaluating principal stress difference (isochromatic) with a single polariscope configuration. Non-inconsistencies or ambiguities.
Disadvantage: A seed point to start must be carefully introduced- Disadvantage: The fringe demodulation is obtaining by solving a cost function per every point
Disadvantage: Color search strategies must be included
Table 2.
Representation of Isochromatic Patterns in the Hybrid Load Stepping Methoda
Representation of a disk observed through a dark field polariscope when $F = 2500N$ load compression, and $\Delta F = 10\% F$.
Table 3.
Photoelasticity Images from a Similar Model but Different Stress Magnitude
Table 4.
Effect of Light Sources Within the Fringe Visualization Processa
Stress maps were normalized with respect to a maximum value of six fringe orders.
Table 5.
Isochromatic Fringes from Applications of Different Engineering Areas
Table 6.
Benchmarks for Experiments in Photoelasticity Studies