High accuracy measurement of heterogeneous deformation field using spatial-temporal subset digital image correlation

Measurement ◽  
2020 ◽  
Vol 156 ◽  
pp. 107605 ◽  
Author(s):  
Tongzhen Xing ◽  
Haibin Zhu ◽  
Lu Wang ◽  
Guangyan Liu ◽  
Qinwei Ma ◽  
...  
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
High Accuracy ◽  
Deformation Field ◽  
Image Correlation ◽  
Accuracy Measurement ◽  
Heterogeneous Deformation ◽  
High Accuracy Measurement

Study on Lüders Deformation in Welded Mild Steel Using Infrared Thermography and Digital Image Correlation

2012 ◽  
Vol 585 ◽  
pp. 82-86 ◽  
Author(s):  
N. Srinivasan ◽  
N. Raghu ◽  
B. Venkatraman
Keyword(s):  
Digital Image Correlation ◽  
Mild Steel ◽  
Infrared Thermography ◽  
Digital Image ◽  
Tensile Testing ◽  
Image Correlation ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Testing ◽  
Heterogeneous Deformation ◽  
Lüders Band

Studies on characterizing heterogeneous deformations in many materials under different loading conditions using imaging NDE techniques like Infrared thermography (IRT) and Digital image correlation (DIC) began in the last decade and have been reported by many researchers. This work aims in experimental investigation of one such heterogeneous deformation namely Lüders band phenomenon in welded IS 2062 E250-B mild steel during monotonic, uniaxial tensile testing using IRT and DIC. Also attempt has been made to study the generation of pre-yield microstrain in welded material. An understanding of nucleation and propagation of Lüders band in welded specimen is made based on temperature and strain changes.

Improvement of heterogeneous deformation measurement in digital image correlation

2017 ◽  
Vol 31 (19-21) ◽  
pp. 1740032
Author(s):  
Huan Shen ◽  
Zhonghan Liang ◽  
Baishun Cheng
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Displacement Field ◽  
Large Strain ◽  
Small Strain ◽  
Deformation Measurement ◽  
Image Correlation ◽  
Subset Size ◽  
Information Reduction ◽  
Heterogeneous Deformation

Heterogeneous deformation measurement using traditional digital image correlation (DIC) has times error of homogeneous deformation due to localized complexity. In case of small strain window, displacement field error will substantially corrupt the derived strain. On the contrary, large strain window will induce a reasonable information reduction in particular of heterogeneous deformation. In this paper, a novel parameter was put forward to correct displacement field and select strain subset size dynamically. This parameter was determined by localized displacement field that is called the localized displacement non-uniform intensity [Formula: see text]. In addition, there is a simple and effective method to eliminate the rigid body rotation impact on strain measurement. A series of speckle images containing different heterogeneous deformation are simulated finally. Results show that the accuracy on the displacement and strain field can be substantially improved especially in heterogeneous deformation fields.

scholarly journals High Accurate Crack Reconstruction Based on an Improved Discontinuous Digital Image Correlation: Subset Restore and Adaptation Method

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Wenzhi Tang ◽  
Hanbin Xiao ◽  
Chentong Chen
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
High Speed ◽  
Large Scale ◽  
High Accuracy ◽  
Image Correlation ◽  
Small Scale ◽  
Adaptation Algorithm ◽  
Subset Size ◽  
Nondestructive Technique

Digital image correlation (DIC) is an efficient nondestructive technique for measuring surface displacement in engineering. However, standard DIC is restricted to continuous deformation, and the existing discontinuous DIC (DDIC) techniques are only able to measure small-scale cracks. In this report, a novel subset restore model and a corresponding subset size adaptation algorithm are presented to overcome this limitation for crack-state and displacement field reconstruction for large-scale cracks. The technique introduces a new subset restore method for splicing the segmented subset by tracing the motion trajectory caused by pure discontinuities. The proposed model facilitates the calculation of the rotation angle and the pivot of the subset movement. The subset size adaptation algorithm is designed based on an evaluation of the intensity gradient and correlation coefficient to allow the model to achieve high accuracy. Validation of the approach was performed using two typical crack models, by deforming a numerically synthesized Gaussian speckle image according to the deformation data from finite element analysis (FEA) results and photographing a laboratory tensile test with a high-speed CCD camera, respectively. The results validate the efficacy and high accuracy of the proposed approach compared to standard DIC in the reconstruction of the displacement fields in both continuous and discontinuous regions. The accuracy of resultant displacement reconstruction achieves approximately 0.015 pixels and 0.05 pixels in continuous region and crack vicinity, respectively.

Measurement and Analysis of Concrete Deformation Field Based on CT and Digital Image Correlation Method

2020 ◽  
Vol 57 (20) ◽  
pp. 200401
Author(s):  
王凡 Wang Fan ◽  
赵亮 Zhao Liang ◽  
吴晓东 Wu Xiaodong ◽  
党发宁 Dang Faning
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Correlation Method ◽  
Deformation Field ◽  
Image Correlation ◽  
Digital Image Correlation Method ◽  
Measurement And Analysis

Stress Field Analysis in Orthogonal Cutting Process Using Digital Image Correlation Technique

2016 ◽  
Vol 139 (3) ◽  
Author(s):  
Dong Zhang ◽  
Xiao-Ming Zhang ◽  
Wen-Jie Xu ◽  
Han Ding
Keyword(s):  
Digital Image Correlation ◽  
Stress Field ◽  
Elastic Deformation ◽  
Digital Image ◽  
Cutting Forces ◽  
Orthogonal Cutting ◽  
Deformation Field ◽  
Machining Process ◽  
Image Correlation ◽  
Dic Technique

Cutting stress field in machining process plays a significant role in the understanding of cutting mechanics and prediction of surface integrity, tool wear, and failure. It is in great need to get accurate and reliable cutting stresses in the chip formation zone. In this paper, a new methodology to obtain the cutting stress field is proposed. The deformation field containing elastic as well as plastic parts can be obtained via digital image correlation (DIC) technique. The orthogonal cutting stress field can be obtained with the experimental determined deformation field and material constitutive model as inputs. However, the challenge is to handle the inaccuracy of infinitesimal elastic deformation involved in the total deformation due to the inaccuracy of the obtained images. We develop a method to modify the hydrostatic pressure field based on mechanical equilibrium equations to compensate the inaccuracy of elastic deformation part. Besides, Eulerian logarithmic strain based on a least square plane fit on a subset of displacement data is adopted to reduce the image noise. The stress distribution along the shear plane and tool–chip interface can be extracted and integrated to calculate cutting forces. A feasibility study is performed by comparing the cutting forces predicted based on this new method against the experimental measurements. The comparison of cutting parameters obtained through DIC technique with finite element method (FEM) predictions is also made.

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