scholarly journals Accurate Measurement of Strain in Noncontact Surface Deformation Using Subset-Based Digital Image Correlation

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
S. Agnes Shifani ◽  
M. S. Godwin Premi
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Surface Deformation ◽  
Computational Cost ◽  
Computation Time ◽  
Image Correlation ◽  
Step Size ◽  
Time Required ◽  
Precision Rate ◽  
Number Of Iterations

The measurement of strain using some contact techniques has some drawbacks like less accuracy and it takes larger computation time for finding each location of subpixels. Thus, a faster noncontact Digital Image Correlation (DIC) mechanism is utilized along with the traditional techniques to measure the strain. The Newton-Raphson (NR) technique is considered to be an accepted mechanism for accurate tracking of different intensity relocation. Generally, the issue regarding the DIC mechanism is its computational cost. In this paper, an interpolation technique is utilized to accomplish a high precision rate and faster image correlation; thereby it reduces the computation time required for finding the matched pixel and viably handles the rehashing relationship process. Hence, the proposed mechanism provides better efficiency along with a reduced number of iterations required for finding the identity. The number of iterations can be reduced using the Sum of Square of Subset Intensity Gradients (SSSIG) method. The evaluation of the projected scheme is tested with different images through various parameters. Finally, the outcome indicates that the projected mechanism takes only a few milliseconds to match the best matching location, whereas the prevailing techniques require 16 seconds for the same operation with the same step size. This demonstrates the effectiveness of the proposed scheme.

scholarly journals Accurate Measurement of Strain in Non-Contact Surface Deformation Using Subset Based Digital Image Correlation

2021 ◽  
Author(s):  
Agnes Shifani S ◽  
Godwin Premi M S
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Surface Deformation ◽  
Computational Cost ◽  
Computation Time ◽  
Image Correlation ◽  
Step Size ◽  
Interpolation Technique ◽  
Time Required ◽  
Precision Rate

Abstract The measurement of strain using some contact techniques has some drawbacks like less accuracy and it takes larger computation time for finding each location of sub-pixels. Thus, a faster non-contact Digital Image Correlation (DIC) mechanism is utilized along with the traditional techniques to measure the strain. The Newton-Raphson (NR) technique is considered to be an accepted mechanism for accurate tracking of different intensity relocation. Generally, the issue regarding the DIC mechanism is its computational cost. In this paper an interpolation technique is utilized to accomplish a high precision rate and faster image correlation, thereby it reduces the computation time required for finding the matched pixel and viably handles the rehashing relationship process. Hence the proposed mechanism provides better efficiency along with a reduced number of iterations required for finding the identity. The number of iteration can be reduced using the Sum of Square of Subset Intensity Gradient (SSSIG) method. The evaluation of the projected scheme is tested with different images through various parameters. Finally, the outcome indicates that the projected mechanism takes only a few milliseconds to match the best matching location whereas the prevailing techniques require 16 seconds for the same operation with the same step size. This demonstrates the effectiveness of the proposed scheme.

Predicting strains in embedded reinforcement based on surface deformation obtained by digital image correlation technique

2021 ◽  
Author(s):  
Ali Mirzazade ◽  
Cosmin Popescu ◽  
Thomas Blanksvärd ◽  
Björn Täljsten
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Surface Deformation ◽  
Local Strain ◽  
Surface Strain ◽  
Image Correlation ◽  
Correlation Technique ◽  
Proposed Model ◽  
Structural Inspection ◽  
Semi Empirical

<p>This study is carried out to assess the applicability of using a digital image correlation (DIC) system in structural inspection, leading to deploy innovative instruments for strain/stress estimation along embedded rebars. A semi-empirical equation is proposed to predict the strain in embedded rebars as a function of surface strain in RC members. The proposed equation is validated by monitoring the surface strain in ten concrete tensile members, which are instrumented by strain gauges along the internal steel rebar. One advantage with this proposed model is the possibility to predict the local strain along the rebar, unlike previous models that only monitored average strain on the rebar. The results show the feasibility of strain prediction in embedded reinforcement using surface strain obtained by DIC.</p>

scholarly journals A Review of Surface Deformation and Strain Measurement Using Two-Dimensional Digital Image Correlation

2016 ◽  
Vol 23 (3) ◽  
pp. 461-480 ◽  
Author(s):  
Sze-Wei Khoo ◽  
Saravanan Karuppanan ◽  
Ching-Seong Tan
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Strain Measurement ◽  
Surface Deformation ◽  
Optical Measurement ◽  
Image Correlation ◽  
Two Dimensional ◽  
Full Field ◽  
Computation Efficiency ◽  
Dimensional Measurements

Abstract Among the full-field optical measurement methods, the Digital Image Correlation (DIC) is one of the techniques which has been given particular attention. Technically, the DIC technique refers to a non-contact strain measurement method that mathematically compares the grey intensity changes of the images captured at two different states: before and after deformation. The measurement can be performed by numerically calculating the displacement of speckles which are deposited on the top of object’s surface. In this paper, the Two-Dimensional Digital Image Correlation (2D-DIC) is presented and its fundamental concepts are discussed. Next, the development of the 2D-DIC algorithms in the past 33 years is reviewed systematically. The improvement of 2DDIC algorithms is presented with respect to two distinct aspects: their computation efficiency and measurement accuracy. Furthermore, analysis of the 2D-DIC accuracy is included, followed by a review of the DIC applications for two-dimensional measurements.

The Wavelike Plastic Deformation of Single Crystal Copper

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Russell J. McDonald ◽  
Christos Efstathiou ◽  
Peter Kurath
Keyword(s):  
Plastic Deformation ◽  
Digital Image Correlation ◽  
Strain Rate ◽  
Single Crystal ◽  
Digital Image ◽  
Surface Deformation ◽  
Image Correlation ◽  
Nominal Strain Rate ◽  
Single Crystal Copper ◽  
Nominal Strain

The purpose of this work is to explore nonuniform plastic flow at small length- and time-scales. Pure single crystal copper tensile specimens were pulled along the [6¯ 5 6] crystal axis at three nominal strain-rates: 0.01%/s, 0.04%/s, and 0.10%/s. Simultaneously, the surface deformation was monitored with in situ digital image correlation over a length-scale of ∼100 μm and a time-scale of 0.07–0.2 s. Sequential digital image correlation strain-rate fields show compelling evidence of a wavelike plastic deformation that is proportional to the nominal strain-rate and decelerates with increasing strain hardening. While a mechanism responsible for the waves is not identified, a methodology correlating observations of multiple researchers is forwarded.

scholarly journals Key aspects of digital image correlation in impact tests of reinforced concrete beams

2019 ◽  
Author(s):  
Morgan Johansson ◽  
Rasmus Rempling ◽  
Gonzalo S. D. de Ulzurrun ◽  
Carlos Zanuy
Keyword(s):  
Reinforced Concrete ◽  
Digital Image Correlation ◽  
Digital Image ◽  
High Speed ◽  
Concrete Beams ◽  
Computational Cost ◽  
Reinforced Concrete Beams ◽  
Image Correlation ◽  
High Speed Photography ◽  
Key Aspects

<p>This paper studies 2-D high speed photography combined with digital image correlation (DIC) applied to experimental research of reinforced concrete beams at moderate loading rates. The aim of the present research is to understand the influence of 2-D DIC set-up parameters in the results. Drop-weight tests have been completed in 1180 × 100 × 100 mm longitudinally reinforced concrete beams. The study has confirmed results sensitivity to image subdivision and mesh properties. While smaller subdivision sizes allow to obtain results nearby boundaries, being more suitable to study local effects, larger sizes enhance computational cost, increase mesh stability and accuracy. A discussion of key aspects of 2-D DIC for measuring different parameters (such as acceleration, displacements, strains and strain-rate) is presented along this paper.</p>

Determination of Flexural Properties of Rigid PUR Foams Using Digital Image Correlation

2014 ◽  
Vol 216 ◽  
pp. 116-121 ◽  
Author(s):  
Tudor Voiconi ◽  
Emanoil Linul ◽  
Liviu Marşavina ◽  
Tomasz Sadowski ◽  
Marcin Kneć
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Surface Deformation ◽  
Flexural Modulus ◽  
Image Correlation ◽  
Flexural Properties ◽  
Cell Diameter ◽  
2D System ◽  
Increase In Accuracy

Cellular materials represent a new class of materials; main parameters that characterize the cellular structure are relative density, shape of the cell (open or closed), wall thickness and cell diameter. The purpose of this paper is to investigate the microstructure of foams materials and also to determine the flexural properties of this rigid PUR foams using Digital Image Correlation (DIC). The rigid PUR foams cells morphology and pore distribution for three densities (100, 145 and 300 kg/m3) were studied before testing through scanning electron microscopy. Determination of flexural properties was carried out on rectangular beam samples using ARAMIS 2D system. This method provides a substantial increase in accuracy for measuring strain and is based on the calculation of surface deformation using a set of digital images from undeformed stage to different deformed stages. The specimens were subjected to static three points bending tests with loading rate of 2 mm/min, at room temperature and loading was applied in rise direction of the foam. Experimental results show that main mechanical properties such as flexural modulus and flexural strength values increases with increasing of density.

scholarly journals Quantification of Three-Dimensional Surface Deformation using Global Digital Image Correlation

2013 ◽  
Vol 54 (4) ◽  
pp. 557-570 ◽  
Author(s):  
J. van Beeck ◽  
J. Neggers ◽  
P. J. G. Schreurs ◽  
J. P. M. Hoefnagels ◽  
M. G. D. Geers
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Surface Deformation ◽  
Three Dimensional ◽  
Image Correlation ◽  
Dimensional Surface
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