Study on Fracture Characteristics of Concrete by White Light Digital Image Analysis in Frequency Domain

2010 ◽  
Vol 29-32 ◽  
pp. 490-495
Author(s):  
Xin Wei Yang ◽  
Xiu Mei Jin ◽  
Rui Lan Tian

White light digital image analysis in frequency domain has the characteristics of whole-field, non-contact measurement. The measuring system of this method is very simple and the coherent light is not demanded. Gray images before and after deformation which are recorded using CCD camera, digitalized and then analyzed by frequency domain correlation arithmetic can be used to obtain the displacement information. This method is used to study the fracture characteristics of concrete and measure the stress intensity factor of I type crack tip. Comparing the experimental results and theoretical values of the stress intensity factor of I type crack tip, the applicability of this method was certified, which shows that this method is very proper to study the deformation and fracture characteristics of concrete.

2014 ◽  
Vol 915-916 ◽  
pp. 1234-1237
Author(s):  
Jun Jun Li ◽  
Xin Wei Yang ◽  
Wen Guang Shi

The surface displacement of soil mass is an important standard for safety in civil engineering. In this paper, white light digital image analysis in frequency domain is introduced tomeasure surface displacement of soil mass. This method has the characteristics of whole-field, non-contact measurement and the simple measuring system and can obtain displacements by frequency domination correlation arithmetic. Surface displacements of soil mass are obtained by white light digital image analysis in frequency domain. Comparing the experimental results and the theoretical values, the little error exists and the usefulness of this method is certified.


2014 ◽  
Vol 568-570 ◽  
pp. 36-39
Author(s):  
Jun Jun Li ◽  
Xin Wei Yang ◽  
Yan Feng Li

The supporting structure in foundation pit is very important in civil engineering and is used to support the whole foundation pit. Its diaplacement is directly related to the safety of buildings. White light digital image analysis in frequency domain has the advantages of whole-field, non-contact measurement and the simple measuring system and can obtain displacements by frequency domination correlation arithmetic. In this paper, the method was introduced to measure the displacements of supporting structure. The experimental results show the usability of the method for supporting structure in foundation pit.


2010 ◽  
Vol 29-32 ◽  
pp. 496-501 ◽  
Author(s):  
Xin Wei Yang ◽  
Hong Gao Man ◽  
Rui Lan Tian

White light digital image analysis in frequency domain is introduced to study concrete deformation. This method has the characteristics of whole-field, non-contact measurement and the simple measuring system and can obtain displacements by frequency domination correlation arithmetic. Displacements of concrete specimen under axial tension are obtained by white light digital image analysis in frequency domain and then strains and Poisson ratio are calculated. Comparing the experimental results and the theoretical values, the error was little and the effectiveness of this method is certified. The applications of different surface features of concrete are studied.


2019 ◽  
Vol 485 (2) ◽  
pp. 162-165
Author(s):  
V. A. Babeshko ◽  
O. M. Babeshko ◽  
O. V. Evdokimova

The distinctions in the description of the conditions of cracking of materials are revealed. For Griffith–Irwin cracks, fracture is determined by the magnitude of the stress-intensity factor at the crack tip; in the case of the new type of cracks, fracture occurs due to an increase in the stress concentrations up to singular concentrations.


2021 ◽  
Vol 34 (1) ◽  
Author(s):  
Bing Yang ◽  
Zhanjiang Wei ◽  
Zhen Liao ◽  
Shuwei Zhou ◽  
Shoune Xiao ◽  
...  

AbstractIn the digital image correlation research of fatigue crack growth rate, the accuracy of the crack tip position determines the accuracy of the calculation of the stress intensity factor, thereby affecting the life prediction. This paper proposes a Gauss-Newton iteration method for solving the crack tip position. The conventional linear fitting method provides an iterative initial solution for this method, and the preconditioned conjugate gradient method is used to solve the ill-conditioned matrix. A noise-added artificial displacement field is used to verify the feasibility of the method, which shows that all parameters can be solved with satisfactory results. The actual stress intensity factor solution case shows that the stress intensity factor value obtained by the method in this paper is very close to the finite element result, and the relative error between the two is only − 0.621%; The Williams coefficient obtained by this method can also better define the contour of the plastic zone at the crack tip, and the maximum relative error with the test plastic zone area is − 11.29%. The relative error between the contour of the plastic zone defined by the conventional method and the area of the experimental plastic zone reached a maximum of 26.05%. The crack tip coordinates, stress intensity factors, and plastic zone contour changes in the loading and unloading phases are explored. The results show that the crack tip change during the loading process is faster than the change during the unloading process; the stress intensity factor during the unloading process under the same load condition is larger than that during the loading process; under the same load, the theoretical plastic zone during the unloading process is higher than that during the loading process.


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