scholarly journals DIGITAL IMAGE CORRELATION IN ASSESSING STRUCTURED-LIGHT 3D SCANNER’S GANTRY STABILITY: PERFORMING DAVID’S (MICHELANGELO) HIGH-ACCURACY 3D SURVEY

2021 ◽  
Vol XLVI-M-1-2021 ◽  
pp. 463-469
Author(s):  
F. Mugnai ◽  
G. Tucci ◽  
A. Da Re
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Ad Hoc ◽  
Structured Light ◽  
Image Correlation ◽  
3D Scanner ◽  
Freedom Of Movement ◽  
Stability Threshold ◽  
Deformation Patterns ◽  
Dic Technique

Abstract. The paper presents results from applying Digital Image Correlation (DIC) technique to determine deformations and verify stability on a gantry during surveying operations on the Michelangelo’s David at the Galleria dell’Accademia di Firenze museum in Florence. An advanced hi-resolution Structured-light 3D scanner has been used to create a hi-detailed digital twin of the masterpiece. Considering the high scanner sensitivity, a contactless, remote and passive monitoring system of the gantry stability has been chosen to guarantee maximum freedom of movement around the David and avoid any interference during scanning operations. Due to the remarkable elevation of the statue, which reaches almost 7 meters on his pedestal, and considering the cramped operating area around the statue, an ad-hoc gantry has been designed and deployed. The sophisticated scanner’s technique and the extreme hi-resolution required for the survey needed firm gantry stability during scanning operations from one side. The complex geometries and the considerable extension of the statue surface impose extended flexibility and a nimble elevation platform from the other side. Thanks to the DIC technique the gantry stability has been constantly monitored with an accuracy of 0.03 ÷ 0,04 pixels, optimising scanning scheduling and, consequently, operations efficiency. A comparison of scans with post-processed deformation patterns allowed to optimise the scanning schedule, minimising downtime, and maintaining the needed platform stability threshold for effective scanning.

Comparison of Digital Image Correlation (DIC) Technique with Nanomaterial-Based Sensor for the Analysis of Strain Measurements

2021 ◽  
pp. 2150032
Author(s):  
A. Deepak ◽  
D. F. L. Jenkins
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Standard Specimen ◽  
Strain Sensor ◽  
Constant Load ◽  
Strain Sensors ◽  
Image Correlation ◽  
Strain Measurements ◽  
American Society ◽  
Dic Technique

Digital Image Correlation (DIC) techniques can be used to visually map and measure strain in materials such as metals and metallic alloys. The strain induced in an American Society for Testing and Materials (ASTMs) standard specimen can be measured using a DIC technique. Image patterns indicating the localized strain variations as a function of time for the constant load applied were also obtained. Results obtained using the DIC technique were more accurate compared to conventional strain sensors. DIC results were also compared with nanomaterial-based strain sensor output. Localized strain induced in the material can be visualized and quantified analytically using DIC.

scholarly journals Study of size effect using digital image correlation

2015 ◽  
Vol 8 (3) ◽  
pp. 323-340 ◽  
Author(s):  
A. H. A. SANTOS ◽  
R. L. S. PITANGUEIRA ◽  
G. O. RIBEIRO ◽  
R. B. CALDAS
Keyword(s):  
Digital Image Correlation ◽  
Size Effect ◽  
Digital Image ◽  
Concrete Beams ◽  
Image Correlation ◽  
Displacement Fields ◽  
Bending Tests ◽  
Three Point Bending ◽  
New Methods ◽  
Dic Technique

Size effect is an important issue in concrete structures bearing in mind that it can influence many aspects of analysis such as strength, brittleness and structural ductility, fracture toughness and fracture energy, among others. Further this, ever more new methods are being developed to evaluate displacement fields in structures. In this paper an experimental evaluation of the size effect is performed applying Digital Image Correlation (DIC) technique to measure displacements on the surface of beams. Three point bending tests were performed on three different size concrete beams with a notch at the midspan. The results allow a better understanding of the size effect and demonstrate the efficiency of Digital Image Correlation to obtain measures of displacements.

Development of a Railway Track Displacement Monitoring by Using Digital Image Correlation Technique

2014 ◽  
Vol 548-549 ◽  
pp. 683-687 ◽  
Author(s):  
Lenny Iryani ◽  
Hery Setiawan ◽  
Tatacipta Dirgantara ◽  
Ichsan Setya Putra
Keyword(s):  
Digital Image Correlation ◽  
Stress Field ◽  
Digital Image ◽  
Displacement Field ◽  
Image Correlation ◽  
Railway Track ◽  
Remaining Life ◽  
Full Field ◽  
Field Displacement ◽  
Dic Technique

To avoid an unnecessary catastrophic accident due to a failure of a railway track, it is important to have a reliable condition monitoring system for the railway track. The integrity of the railway track can be assessed by monitoring the displacement field of the track, which can then be used to determine the strain and stress field. By knowing the stress history of the track and the S–N curves of the track material, the remaining life of the railway track can be predicted. In the present work, a simple system to monitor and record the displacement field of the railway track has been developed by using Digital Image Correlation (DIC) technique. The set–up to monitor the displacement field of the railway track was developed using a high speed video camera of Nikon J1 to capture the image of the railway track when the train passing through. The DIC technique was then employed off line to measure the displacement field of the 2D image captured. The results showed that the full field displacement measured by using DIC technique gives a good agreement compared to the finite element results. The full field displacement can be used to calculate the strain-stress field, and later on the remaining life assessment can be conducted based on the results.

scholarly journals Vibration Analyses of a Gantry Structure by Mobile Phone Digital Image Correlation and Interferometric Radar

Geomatics ◽  
2021 ◽  
Vol 2 (1) ◽  
pp. 17-35
Author(s):  
Francesco Mugnai ◽  
Antonio Cosentino ◽  
Paolo Mazzanti ◽  
Grazia Tucci
Keyword(s):  
Digital Image Correlation ◽  
Mobile Phone ◽  
Digital Image ◽  
Ad Hoc ◽  
Stability Control ◽  
Image Correlation ◽  
Remote Monitoring System ◽  
Stability Control System ◽  
Survey Accuracy ◽  
Year 2000

The study presents results from applying the Real Aperture Radar interferometry technique and Digital Image Correlation through a mobile phone camera to identify static and dynamic deformations of a gantry during surveying operations on the Michelangelo’s David at the Galleria dell’Accademia di Firenze Museum in Florence. The statue has considerable size and reaches an elevation of more than seven meters on its pedestal. An ad-hoc gantry was designed and deployed, given the cramped operating area around the statue. The scanner had a stability control system that forbid surveying in instrument movements. However, considering the unicity of the survey and its rare occurrence, the previous survey had been carried out in the year 2000; verifying stability and recording deformations is a crucial task, and necessary for validation. As the gantry does not have an on-board stability sensor, and considering the hi-survey accuracy requested, a redundant, contactless, remote monitoring system of the gantry and the statue stability was chosen to guarantee the maximum freedom of movement around the David to avoid any interference during scanning operations. Thanks to the TInRAR technique, the gantry and the statue were monitored with an accuracy of 0.01 mm. At the same time, a Digital Image Correlation analysis was performed on the gantry, which can be considered a Multi-Degree-Of-Freedom (MDOF) system, to accurately calculate the vibration frequency and amplitude. A comparison between TInRAR and DIC results reported substantial accordance in detecting gantry’s oscillating frequencies; a predominant oscillation frequency of 1.33 Hz was identified on the gantry structure by TinSAR and DIC analysis.

scholarly journals Inverse problems with the digital image correlation: approach and applications

2021 ◽  
Vol 15 (57) ◽  
pp. 300-320
Author(s):  
Emanuele Sgambitterra ◽  
Fabrizio Niccoli
Keyword(s):  
Digital Image Correlation ◽  
Inverse Problems ◽  
Digital Image ◽  
Ad Hoc ◽  
Solid Mechanics ◽  
Iterative Algorithms ◽  
Image Correlation ◽  
Estimation Errors ◽  
Pipe Coupling ◽  
Viable Approach

A viable approach to solve inverse problems in elasticity is proposed. It is based on regression algorithms to estimate materials and/or loading parameters by fitting the experimentally-evaluated displacement field to representative analytical solutions. Displacements are measured by the digital image correlation (DIC) technique and they are used as input for numerical procedures able to minimize the estimation errors of the unknowns and to quantify the unavoidable rigid body motions of the samples/components. In addition, thanks to ad-hoc developed iterative algorithms, non-linear phenomena related to high and localized stress/strain states, can be captured successfully. This latter represents a relevant novelty of the methodology as it allows to investigate plasticity-induced mechanisms in solid mechanics which are impossible to analyze with more traditional DIC-based approaches. Three different case studies are considered: 1) estimation of the stress intensity factor in fracture mechanics problems, 2) estimation of the elastic properties of a material by the Brazilian tests, 3) estimation of the contact pressure generated by thermally activated shape memory alloy (SMA) rings used for pipe coupling. The reliability and the accuracy of the method is demonstrated through systematic comparisons of the results with conventional techniques in experimental mechanics.

scholarly journals Analysis for Shear Behavior of SRC Deep Beams Based on Tests, Digital Image Correlation Technique, and Finite Elemental Simulation

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Buqing Chen ◽  
Jun Wu ◽  
Changjun Liu ◽  
Yanhua Liu ◽  
Wenmei Zhou ◽  
...  
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Failure Modes ◽  
Parameter Analysis ◽  
Image Correlation ◽  
Superposition Method ◽  
Deep Beams ◽  
Shear Span ◽  
Depth Ratio ◽  
Dic Technique

Seven steel-reinforced concrete (SRC) deep beams were tested to investigate the shear performance, including peak loads, failure modes, mid-span deflections, and cracking patterns. The parameters include the shear span-to-depth ratio and the dimensions of the steel skeleton. The digital image correlation (DIC) technique was utilized for real-time recording of the in-plane strain and deformation. The experiment results show that the failure modes of specimens could be concluded as two forms: diagonal compression failure and shear failure. The DIC technique was proved to be efficient for tracking the development of crack patterns and recording the failure modes. The corresponding numerical analyses based on experiments were carried out and demonstrated to be a reliable method to simulate the shear response. Furthermore, the most significant parameters and their interactions were identified by finite element models parameter analysis. The steel skeleton height and shear span-to-depth ratio were the main parameters affecting shear capacity. A design formula based on the strength superposition method was presented. The calculated results were basically in agreement with the test results, where the mean and coefficient of variation were 1.04 and 0.09, respectively.

Characterization of LIGA Microsystems Using Digital Image Correlation Technique and SEM Imaging

Aerospace ◽  
2005 ◽  
Author(s):  
Helena (Huiqing) Jin ◽  
Wei-Yang Lu ◽  
Jeff Chames ◽  
Nancy Yang
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Speckle Pattern ◽  
Image Correlation ◽  
Specimen Surface ◽  
Correlation Technique ◽  
Sem Images ◽  
Full Field ◽  
Speckle Patterns ◽  
Dic Technique

A new experimental technique was developed to characterize the mechanical properties of LIGA (an acronym from German words for lithography, electroplating, and molding) materials. An advanced imaging capability, scanning electron microscopy (SEM), with an integrated loading stage allows the acquisition of in situ microstructural images at the micro scale during loading. The load is measured directly from a load cell, and the displacement field is calculated from the SEM images based on the digital image correlation (DIC) technique. The DIC technique is a full-field deformation measurement technique which obtains displacement fields by comparing random speckle patterns on the specimen surface before and after deformation. The random speckle patterns are typically generated by applying a thin layer of material with high contrast to a specimen surface. Alternatively, DIC can also be applied using the microstructural features of a surface as texture patterns for correlation. DIC technique is ideally suited to characterize the deformation field of MEMS structures without the need to generate a random speckle pattern, which can be very challenging on the micro and nanoscale. In this paper, the technique is experimentally demonstrated on a LIGA specimen. The digital images showing LIGA surface features acquired during the loading can serve as random patterns for the DIC method. Therefore, full-field displacement and strain can be obtained directly on the specimen and the errors incurred by the testing system can be eliminated.

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