Digital Image Correlation Based Method of Crack Growth Rate and Fracture Toughness Measurements on Mini-Samples

2013 ◽  
Vol 586 ◽  
pp. 96-99
Author(s):  
Tomasz Brynk ◽  
Anatolii Laptiev ◽  
Oleksandr Tolochyn ◽  
Zbigniew Pakiela
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Mechanical Tests ◽  
Image Correlation ◽  
Optical Measurements ◽  
Displacement Fields ◽  
Strain Measurements ◽  
Special Approach ◽  
Tip Position ◽  
Sintering Method

Modern materials fabrication methods which utilize severe plastic deformation (SPD) do not often allow to obtain enough volume of material to prepare standardized samples for mechanical tests. Therefore, there is a need for mini-samples testing. Mini-samples tests require special approach in terms of precise strain measurements. Accurate strain measurements may be achieved by means of non-contact optical method, namely Digital Image Correlation (DIC). The aim of this work is to present the methodology and results of mini-samples tests in which displacement fields measurements performed by means of DIC and inverse method were utilized for calculation of stress intensity factors and crack tip position tracking. The influence of the subarea of optical measurements for which calculation were performed on the calculations results has been investigated during tests in SPD processed Al alloys and brittle WC-Co sinters produced by means of impact sintering method.

An Experimental Assessment on Umbilical Cable Crushing Using Digital Image Correlation

2016 ◽  
Author(s):  
Caio C. P. Santos ◽  
Celso P. Pesce ◽  
Guilherme R. Franzini ◽  
Olaf O. Otte Filho
Keyword(s):  
Digital Image Correlation ◽  
Cross Sections ◽  
Digital Image ◽  
Mechanical Tests ◽  
Image Correlation ◽  
Displacement Fields ◽  
Element Analysis ◽  
Analysis Methodology ◽  
Correlation System ◽  
Umbilical Cable

Focusing on the integrity of umbilical cable components during the laying operation, particularly on hoses integrity, this paper assesses displacement fields on umbilical cable cross-sections by means of a special crushing test setup. Using a high resolution Digital Image Correlation system (DIC), experiments with two umbilical cables are carried out in a 250 kN mechanical tests rig. Besides measuring the components displacements, applied crushing forces and shoes displacements are acquired. The experimental samples are taken from two HCR-hoses umbilical cables, which have been cases of study of a finite element analysis methodology, recently proposed and presented in OMAE2015, [12]. Experimental analysis and a theoretical-experimental correlation are presented, for both umbilical cables.

scholarly journals Experimental Characterization of the FRCM-Concrete Interface Bond Behavior Assisted by Digital Image Correlation

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1154
Author(s):  
Dario De Domenico ◽  
Antonino Quattrocchi ◽  
Damiano Alizzio ◽  
Roberto Montanini ◽  
Santi Urso ◽  
...  
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Mechanical Tests ◽  
Image Correlation ◽  
Front Face ◽  
Full Field ◽  
Bond Behavior ◽  
Externally Bonded ◽  
Strengthening Technique ◽  
Concrete Interface

Digital Image Correlation (DIC) provides measurements without disturbing the specimen, which is a major advantage over contact methods. Additionally, DIC techniques provide full-field maps of response quantities like strains and displacements, unlike traditional methods that are limited to a local investigation. In this work, an experimental application of DIC is presented to investigate a problem of relevant interest in the civil engineering field, namely the interface behavior between externally bonded fabric reinforced cementitious mortar (FRCM) sheets and concrete substrate. This represents a widespread strengthening technique of existing reinforced concrete structures, but its effectiveness is strongly related to the bond behavior between composite fabric and underlying concrete. To investigate this phenomenon, a set of notched concrete beams are realized, reinforced with FRCM sheets on the bottom face, subsequently cured in different environmental conditions (humidity and temperature) and finally tested up to failure under three-point bending. Mechanical tests are carried out vis-à-vis DIC measurements using two distinct cameras simultaneously, one focused on the concrete front face and another focused on the FRCM-concrete interface. This experimental setup makes it possible to interpret the mechanical behavior and failure mode of the specimens not only from a traditional macroscopic viewpoint but also under a local perspective concerning the evolution of the strain distribution at the FRCM-concrete interface obtained by DIC in the pre- and postcracking phase.

scholarly journals Super Resolution Digital Image Correlation (SR-DIC): an Alternative to Image Stitching at High Magnifications

2021 ◽  
Author(s):  
R. S. Hansen ◽  
D. W. Waldram ◽  
T. Q. Thai ◽  
R. B. Berke
Keyword(s):  
High Resolution ◽  
Digital Image Correlation ◽  
Spatial Resolution ◽  
Digital Image ◽  
Super Resolution ◽  
Image Correlation ◽  
Low Resolution ◽  
Strain Measurements ◽  
Resolution Image ◽  
High Resolution Image

Abstract Background High-resolution Digital Image Correlation (DIC) measurements have previously been produced by stitching of neighboring images, which often requires short working distances. Separately, the image processing community has developed super resolution (SR) imaging techniques, which improve resolution by combining multiple overlapping images. Objective This work investigates the novel pairing of super resolution with digital image correlation, as an alternative method to produce high-resolution full-field strain measurements. Methods First, an image reconstruction test is performed, comparing the ability of three previously published SR algorithms to replicate a high-resolution image. Second, an applied translation is compared against DIC measurement using both low- and super-resolution images. Third, a ring sample is mechanically deformed and DIC strain measurements from low- and super-resolution images are compared. Results SR measurements show improvements compared to low-resolution images, although they do not perfectly replicate the high-resolution image. SR-DIC demonstrates reduced error and improved confidence in measuring rigid body translation when compared to low resolution alternatives, and it also shows improvement in spatial resolution for strain measurements of ring deformation. Conclusions Super resolution imaging can be effectively paired with Digital Image Correlation, offering improved spatial resolution, reduced error, and increased measurement confidence.

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 Investigation by Digital Image Correlation of Mixed Mode I and II Fracture Behavior of Metallic IASCB Specimens with Additive Manufactured Crack-Like Notch

Metals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 400 ◽  
Author(s):  
Ivo Campione ◽  
Tommaso Maria Brugo ◽  
Giangiacomo Minak ◽  
Jelena Janković Tomić ◽  
Nebojša Bogojević ◽  
...  
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Mixed Mode ◽  
Fracture Behavior ◽  
Selective Laser Sintering ◽  
Local Stress ◽  
Fatigue Loading ◽  
Image Correlation ◽  
Mode I ◽  
Displacement Fields

This work investigates the fracture behavior of maraging steel specimens manufactured by the selective laser sintering (SLS) technology, in which a crack-like notch (sharp notch) was directly produced during the additive manufacturing (AM) process. For the evaluation of the fracture toughness, the inclined asymmetrical semi-circular specimen subjected to three points loading (IASCB) was used, allowing to cover a wide variety of Mode I and II combinations. The effectiveness of manufacturing crack-like notches via the SLS technique in metals was evaluated by comparing the obtained experimental results with the ones obtained with pre-cracks induced by fatigue loading. The investigation was carried out by using the digital image correlation (DIC) technique, that allowed the evaluation of the full displacement fields around the crack tip. The displacement field was then used to compute the stress intensity factors (SIFs) for various combinations of Mode I and II, via a fitting technique which relies on the Williams’ model for the displacement. The SIFs obtained in this way were compared to the results obtained with the conventional critical load method. The results showed that the discrepancy between the two methods reduces by ranging from Mode I to Mode II loading condition. Finally, the experimental SIFs obtained by the two methods were described by the mixed mode local stress criterium.

Full-field strain measurements at the micro-scale in fiber-reinforced composites using digital image correlation

2016 ◽  
Vol 140 ◽  
pp. 192-201 ◽  
Author(s):  
Mahoor Mehdikhani ◽  
Mohammadali Aravand ◽  
Baris Sabuncuoglu ◽  
Michaël G. Callens ◽  
Stepan V. Lomov ◽  
...  
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Image Correlation ◽  
Fiber Reinforced Composites ◽  
Field Strain ◽  
Reinforced Composites ◽  
Fiber Reinforced ◽  
Full Field ◽  
Strain Measurements ◽  
Micro Scale
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