Real-Time Digital Image Correlation for Dynamic Strain Measurement

Wu, Rong; Kong, Chen; Li, K.; Zhang, D.

doi:10.1007/s11340-016-0133-6

Cited by 51 publications

(24 citation statements)

References 39 publications

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“…Conversely, the DIC technique can be easily implemented, as demonstrated by its wide range of applications [ 19 , 20 , 21 , 22 , 23 ]. Video extensometry, initially based on feature-based image registration techniques that is evolving into a real-time DIC [ 24 ], can measure high strain level with small errors. However, strain errors increases if the specimen’s dimensions decrease [ 25 ].…”

Section: Introductionmentioning

confidence: 99%

Experimentally Achievable Accuracy Using a Digital Image Correlation Technique in measuring Small-Magnitude (<0.1%) Homogeneous Strain Fields

2018

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Measuring small-magnitude strain fields using a digital image correlation (DIC) technique is challenging, due to the noise-signal ratio in strain maps. Here, we determined the level of accuracy achievable in measuring small-magnitude (<0.1%) homogeneous strain fields. We investigated different sets of parameters for image processing and imaging pre-selection, based on single-image noise level. The trueness of DIC was assessed by comparison of Young’s modulus (E) and Poisson’s ratio (ν) with values obtained from strain gauge measurements. Repeatability was improved, on average, by 20–25% with experimentally-determined optimal parameters and image pre-selection. Despite this, the intra- and inter-specimen repeatability of strain gauge measurements was 5 and 2.5 times better than DIC, respectively. Moreover, although trueness was also improved, on average, by 30–45%, DIC consistently overestimated the two material parameters by 1.8% and 3.2% for E and ν, respectively. DIC is a suitable option to measure small-magnitude homogeneous strain fields, bearing in mind the limitations in achievable accuracy.

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Section: Introductionmentioning

confidence: 99%

Experimentally Achievable Accuracy Using a Digital Image Correlation Technique in measuring Small-Magnitude (<0.1%) Homogeneous Strain Fields

2018

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“…3 In contrast, the proposed DIC approach can achieve accurate strain measurement at 60 Hz in a 2-D application. 21 In this study, a robust and automatic strategy for real-time measurement of 3-D motion has been presented. As shown in Table 1, a measurement accuracy of −0.25% in the x-direction (in-plane) and 1.17% in the z-direction (out-of-plane) was achieved.…”

Section: Discussionmentioning

confidence: 99%

“…As reported previously, this algorithm has been applied in fatigue testing for real-time characterization of strain at a rate of 60 Hz for a camera with sampling rate of 62.5 fps. 21 In 3-D measurements, the motion of the object is recorded in sequences with two synchronized cameras. To achieve real-time measurement, the aforementioned correlation algorithm is conducted between image pairs and two sequential images, respectively.…”

Section: Real-time Three-dimensional Digital Image Correlationmentioning

confidence: 99%

Real-time three-dimensional digital image correlation for biomedical applications

Wu¹,

Arola

et al. 2016

J. Biomed. Opt

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Digital image correlation (DIC) has been successfully applied for evaluating the mechanical behavior of biological tissues. A three-dimensional (3-D) DIC system has been developed and applied to examining the motion of bones in the human foot. To achieve accurate, real-time displacement measurements, an algorithm including matching between sequential images and image pairs has been developed. The system was used to monitor the movement of markers which were attached to a precisely motorized stage. The accuracy of the proposed technique for in-plane and out-of-plane measurements was found to be ?0.25% and 1.17%, respectively. Two biomedical applications were presented. In the experiment involving the foot arch, a human cadaver lower leg and foot specimen were subjected to vertical compressive loads up to 700 N at a rate of 10??N/s and the 3-D motions of bones in the foot were monitored in real time. In the experiment involving distal tibio fibular syndesmosis, a human cadaver lower leg and foot specimen were subjected to a monotonic rotational torque up to 5 Nm at a speed of 5 deg per min and the relative displacements of the tibia and fibula were monitored in real time. Results showed that the system could reach a frequency of up to 16 Hz with 6 points measured simultaneously. This technique sheds new lights on measuring 3-D motion of bones in biomechanical studies.

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“…Since then, almost all the researches related to DIC adopted IC-GN algorithm for sub-pixel registration, which can be summed up as first-order and second-order IC-GN. First-order IC-GN is extensively used for real-time human pulse monitoring [ 18 ], real-time dynamic strain measurement [ 19 ], and 3D shape measurement [ 7 ]. It is worth noting that first-order warp function is a linear transformation, which can only characterize local translation, rotation, and uniform mapping.…”

Section: Introductionmentioning

confidence: 99%

Comparative Analysis of Warp Function for Digital Image Correlation-Based Accurate Single-Shot 3D Shape Measurement

Yang

Chen

2018

Sensors

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Digital image correlation (DIC)-based stereo 3D shape measurement is a kind of single-shot method, which can achieve high precision and is robust to vibration as well as environment noise. The efficiency of DIC has been greatly improved with the proposal of inverse compositional Gauss-Newton (IC-GN) operators for both first-order and second-order warp functions. Without the algorithm itself, both the registration accuracy and efficiency of DIC-based stereo matching for shapes with different complexities are closely related to the selection of warp function, subset size, and convergence criteria. Understanding the similarity and difference of the impacts of prescribed subset size and convergence criteria on first-order and second-order warp functions, and how to choose a proper warp function and set optimal subset size as well as convergence criteria for different shapes are fundamental problems in realizing efficient and accurate 3D shape measurement. In this work, we present a comparative analysis of first-order and second-order warp functions for DIC-based 3D shape measurement using IC-GN algorithm. The effects of subset size and convergence criteria of first-order and second-order warp functions on the accuracy and efficiency of DIC are comparatively examined with both simulation tests and real experiments. Reference standards for the selection of warp function for different kinds of 3D shape measurement and the setting of proper convergence criteria are recommended. The effects of subset size on the measuring precision using different warp functions are also concluded.

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Real-Time Digital Image Correlation for Dynamic Strain Measurement

Cited by 51 publications

References 39 publications

Experimentally Achievable Accuracy Using a Digital Image Correlation Technique in measuring Small-Magnitude (<0.1%) Homogeneous Strain Fields

Experimentally Achievable Accuracy Using a Digital Image Correlation Technique in measuring Small-Magnitude (<0.1%) Homogeneous Strain Fields

Real-time three-dimensional digital image correlation for biomedical applications

Comparative Analysis of Warp Function for Digital Image Correlation-Based Accurate Single-Shot 3D Shape Measurement

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