scholarly journals Formation of a complete stress-strain curve of concrete using digital image corellation

2021 ◽  
Vol 3 (7 (111)) ◽  
pp. 37-44
Author(s):  
Yaroslav Blikharskyy ◽  
Andrii Pavliv
Keyword(s):  
Reinforced Concrete ◽  
Digital Image Correlation ◽  
Digital Image ◽  
Concrete Structures ◽  
Strain Curve ◽  
Image Correlation ◽  
Correlation Technique ◽  
Reinforced Concrete Structures ◽  
Stress Strain Curve ◽  
Stress Strain

This paper reports the development and verification of a new procedure for formation of a complete stress-strain curve of concrete with a downward region of strain by using a digital image correlation method. A new technique to build spectle patterns on the surface of concrete is described. That makes it possible to accurately enough reproduce the spectle patterns on the surface of concrete and perform a high-quality analysis of strains involving digital image correlation. The advantages of this research technique have been established when predicting the formation of internal cracks in concrete followed by their propagation. In addition, using the digital image correlation methodology makes it possible to obtain strains of the entire studied plane of the sample at each stage of loading. This procedure provides an opportunity to investigate a change in strains and the movement of individual points or areas when studying concrete surfaces. That is a relevant issue as it enables more detailed diagnostics of existing reinforced concrete structures. To check the accuracy of this procedure application, a mechanical gauge with an accuracy of 0.001 mm was additionally installed. 2 high-speed monochrome CCD cameras with different lenses were used in determining concrete strains involving the digital image correlation technique. The deformations were controlled with a period of time every 250 ms. The load was controlled by an additional third camera with a speed of 50 frames/second. The result of the experimental study is the formed full concrete destruction diagram with a downward region of strain. The deviation of the results of strains based on the mechanical gauge with an accuracy of 0.001 mm with a base of 200 mm from those acquired by the digital image correlation procedure was mainly up to 10 %, which confirms the reliability of the results. The results of this work allow a more accurate calculation of reinforced concrete structures in the practice of design, inspection, or reinforcement of existing structures

Digital Image Correlation and Noise-filtering Approach for the Cracking Assessment of Massive Reinforced Concrete Structures

Strain ◽  
2016 ◽  
Vol 52 (6) ◽  
pp. 503-521 ◽  
Author(s):  
G. Ruocci ◽  
C. Rospars ◽  
G. Moreau ◽  
P. Bisch ◽  
S. Erlicher ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Digital Image Correlation ◽  
Digital Image ◽  
Concrete Structures ◽  
Image Correlation ◽  
Reinforced Concrete Structures ◽  
Noise Filtering ◽  
Filtering Approach

Determination of constitutive relation from miniature tensile test with digital image correlation

2020 ◽  
Vol 55 (3-4) ◽  
pp. 99-108 ◽  
Author(s):  
Yunlu Zhang ◽  
Sreekar Karnati ◽  
Tan Pan ◽  
Frank Liou
Keyword(s):  
Digital Image Correlation ◽  
Tensile Test ◽  
Constitutive Relation ◽  
Digital Image ◽  
Strain Curve ◽  
True Stress ◽  
Image Correlation ◽  
Stress Strain Curve ◽  
Stress Strain

The determination of constitutive relation from the miniature tensile test is of high interest in multiple areas. Here, a convenient experimental method is proposed to determine the true stress–strain curve from the miniature tensile test. The instantaneous cross-sectional area is estimated by only one camera in aid of digital image correlation technique. This method was applied on commercial pure titanium and aluminum 6061 alloys, and the results indicate that the extracted true stress–strain curves are not scale-dependent. The derived mechanical properties from miniature specimens match well with the results of standard specimens. The correctness of the true stress–strain curve was evaluated by the finite element analysis method. The results suggest that the derived true stress–strain curve is capable to represent the constitutive behavior of the tested materials.

A method of the direct measurement of the true stress–strain curve over a large strain range using multi-camera digital image correlation

2018 ◽  
Vol 107 ◽  
pp. 194-201 ◽  
Author(s):  
Junrui Li ◽  
Guobiao Yang ◽  
Thorsten Siebert ◽  
Ming F. Shi ◽  
Lianxiang Yang
Keyword(s):  
Digital Image Correlation ◽  
Direct Measurement ◽  
Digital Image ◽  
Large Strain ◽  
Strain Curve ◽  
Strain Range ◽  
True Stress ◽  
Image Correlation ◽  
Stress Strain Curve ◽  
Stress Strain

scholarly journals A New S-Shape Specimen for Studying the Dynamic Shear Behavior of Metals

Metals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 838 ◽  
Author(s):  
Ali Arab ◽  
Yansong Guo ◽  
Qiang Zhou ◽  
Pengwan Chen
Keyword(s):  
Shear Stress ◽  
Digital Image Correlation ◽  
Digital Image ◽  
Strain Curve ◽  
Shear Behavior ◽  
Image Correlation ◽  
Specimen Geometry ◽  
Dynamic Shear ◽  
Stress Strain Curve ◽  
Stress Strain

A new S-shaped specimen geometry is developed in this study to investigate the shear behavior of materials under dynamic shear condition. Traditionally, hat-shaped geometry is used to study the dynamic shear of materials by a conventional split Hopkinson pressure bar apparatus. However, in this geometry, the force equilibrium on the two sides of the sample is difficult to fulfill, and the stress field in the shear region is not homogeneous. Hence, the calculated shear stress–strain curve from this geometry is not precise. To overcome this problem, the new S-shaped specimen is designed to achieve accurate shear stress–strain curve. This geometry can be used in a wide range of strain rates and does not require additional machining process for microstructure observation. The new S-shaped specimen is successfully coupled with digital image correlation method because of the flat surface. Digital image correlation results indicate that the fracture patterns of the new S-shaped specimen occur with maximum shear strains in the shear region in the middle of the sample. This result is also validated by finite element model simulation. The new S-shaped specimen geometry can be used to study the dynamic shear behavior of various metals.

scholarly journals Plasticity and Deformation Mechanisms of Ultrafine-Grained Ti in Necking Region Revealed by Digital Image Correlation Technique

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 574
Author(s):  
Yonghao Zhao ◽  
Yanglin Gu ◽  
Yazhou Guo
Keyword(s):  
Stress State ◽  
Digital Image Correlation ◽  
Digital Image ◽  
Strain Curve ◽  
Grain Boundary Sliding ◽  
Image Correlation ◽  
Coarse Grained ◽  
Correlation Technique ◽  
Stress Strain ◽  
Ultrafine Grained

The conventional engineering stress-strain curve could not accurately describe the true stress-strain and local deformability of the necking part of tensile specimens, as it calculates the strain by using the whole gauge length, assuming the tensile specimen was deformed uniformly. In this study, we employed 3D optical measuring digital image correlation (DIC) to systematically measure the full strain field and local strain during the whole tensile process, and calculate the real-time strain and actual flow stress in the necking region of ultrafine-grained (UFG) Ti. The post-necking elongation and strain hardening exponent of the UFG Ti necking part were then measured as 36% and 0.101, slightly smaller than those of the coarse grained Ti (52% and 0.167), suggesting the high plastic deformability in the necking part of the UFG Ti. Finite elemental modeling (FEM) indicates that when necking occurs, strain is concentrated in the necking region. The stress state of the necking part was transformed from uniaxial in the uniform elongation stage to a triaxial stress state. A scanning electron microscopic (SEM) study revealed the shear and ductile fracture, as well as numerous micro shear bands in the UFG Ti, which are controlled by cooperative grain boundary sliding. Our work revealed the large plastic deformability of UFG metals in the necking region under a complex stress state.

scholarly journals Crack Propagation Analysis of Synthetic vs. Steel vs. Hybrid Fibre-Reinforced Concrete Beams Using Digital Image Correlation Technique

2020 ◽  
Vol 14 (1) ◽  
Author(s):  
Aniket B. Bhosale ◽  
S. Suriya Prakash
Keyword(s):  
Reinforced Concrete ◽  
Digital Image Correlation ◽  
Digital Image ◽  
Fracture Behaviour ◽  
Process Zone ◽  
Reinforced Concrete Beams ◽  
Image Correlation ◽  
Correlation Technique ◽  
Fibre Reinforced Concrete ◽  
Hybrid Fibre

Abstract Improvement in fracture behaviour of fibre-reinforced concrete (FRC) due to the inclusion of various types and combinations of fibres is widely reported. The fracture behaviour of FRC needs to be fully understood for the optimum use of these fibres in structural elements. Fracture behaviours of synthetic fibre-reinforced concrete (SynFRC), hybrid fibre-reinforced concrete (HFRC) and steel fibre-reinforced concrete (SFRC) are investigated in this study using digital image correlation (DIC) technique. This work focuses on improvement in the structural performance of FRC through a comprehensive study of the change in the crack length, crack opening and fracture process zone (FPZ) due to different fibres addition and their combinations. Three distinct fibre dosages of 0.50%, 0.75%, and 1.00%, of macro-polyolefin fibres, hooked end steel fibres and their hybrid combination are regarded as research parameters. Test outcomes indicate that HFRC offers higher post-cracking resistance when compared to SynFRC. SFRC showcases superior fracture performance than that of HFRC and SynFRC. Full-field strain measurements from DIC are used to measure the crack openings at different load levels during the fracture tests. Results of DIC analysis show good agreement with experimental measurements. Continuous monitoring of strain contours using DIC reveals the effective engagement of fibres along the depth at higher dosages for HFRC when compared to that of SynFRC. Also, HFRC had longer cracks than SFRC at a particular load.

Research on the Surface Deformability of Reinforced Concrete Beams with the Use of Digital Image Correlation Method

2015 ◽  
Vol 240 ◽  
pp. 25-30
Author(s):  
Rafal Ostromecki ◽  
Karol Suprynowicz
Keyword(s):  
Reinforced Concrete ◽  
Digital Image Correlation ◽  
Digital Image ◽  
Strain Distribution ◽  
Concrete Beams ◽  
Concrete Structures ◽  
Correlation Method ◽  
Reinforced Concrete Beams ◽  
Image Correlation ◽  
Digital Image Correlation Method

The results of experimental research on a single span reinforced concrete beams are presented in the paper. The study was undertaken to explain some issues, amongst which the most important one was the recognition of strain distribution in the shear zone of RC beams. It was decided to adopt the modified Digital Image Correlation Method (DIC) and the software created by K. Suprynowicz to follow the surface deformations. This was the first application of the software to the concrete structures behaviour analysis. Hence, another aim of the study was to confirm the proper susceptibility and usefulness of this tool for further research on concrete elements. What’s more the scope of the software future development was defined, that would allow for observation of some particular phenomena characteristic for concrete, like cracking. Finally, the conclusion is presented, that application of the proposed variant of DIC method to concrete structures is promising, although for the recognition of shear strain distribution it requires increasing the accuracy by increasing spatial resolution of images and modifications of the software.

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