Ductile damage measurement and necking analysis of metal sheets based on digital image correlation and direct current potential drop methods

2014 ◽  
Vol 23 (8) ◽  
pp. 1133-1149 ◽  
Author(s):  
Saijun Zhang ◽  
Qinxiang Xia ◽  
Wenfang Li ◽  
Xuhui Zhou
Keyword(s):  
Digital Image Correlation ◽  
Direct Current ◽  
Digital Image ◽  
Potential Drop ◽  
Tensile Loading ◽  
Image Correlation ◽  
Ductile Damage ◽  
Uniaxial Tensile ◽  
Direct Current Potential Drop ◽  
Current Potential

In this study, a damage measurement procedure is proposed, which combines both digital image correlation and direct current potential drop techniques to evaluate quantitatively the ductile damage in metal sheets during uniaxial tensile loading. Digital image correlation and direct current potential drop techniques are applied to measure the full-field deformation and overall electrical resistance of the region of interest of the specimen during tensile loading. The basic principles, methodology and derivation process are presented in detail. A professional data processing system based on MATLAB is developed to characterize the deformation–resistance–damage relationship during uniaxial tensile loading. The ductile damage can be evaluated conveniently by the proposed approach, and the experimental results so obtained are consistent with those derived by using micro-hardness technique. The necking stage during uniaxial tension is discussed in detail, and it has been shown that the onsets of diffused necking and localized necking can be determined according to the relationship between the major principle true strain and loading steps. Further, the onset of the localized necking can be used to estimate accurately whether the material is going to rupture.

Multi-Lead Direct Current Potential Drop (DCPD) for In-Situ Health Monitoring of Ceramic Matrix Composites

2018 ◽  
Author(s):  
Yogesh P. Singh ◽  
Michael J. Presby ◽  
Kannan Manigandan ◽  
Gregory N. Morscher
Keyword(s):  
Damage Detection ◽  
Direct Current ◽  
Ceramic Matrix Composites ◽  
Potential Drop ◽  
Ceramic Matrix ◽  
Image Correlation ◽  
Matrix Composites ◽  
Direct Current Potential Drop ◽  
Current Potential

The method of direct current potential drop (DCPD) can be utilized as an effective, and convenient approach for in-situ damage detection, and as a non-destructive evaluation technique. We present the results from use of a multiprobe DCPD technique for in-situ damage detection in loading of a SiC/SiC composite. It is shown that in three different modes of loading (monotonic, fatigue, and cyclic load-unload), the sensing capabilities of DCPD technique compares well to the techniques of modal acoustic emission (AE) and digital image correlation (DIC). It was also found that DCPD technique provides a far earlier warning of failure under fatigue loading than the other two methods. In addition, we show that strategically placed multiple voltage leads on the specimen surface provides a promising way of qualitatively determining the crack initiation site. Therefore, the use of multiple lead DCPD method, together with other techniques, provides a viable option for sensing damage in ceramic matrix composites (CMCs) with complex geometries, and for applications at higher temperatures.

Multi-Lead Direct Current Potential Drop Method for In Situ Health Monitoring of Ceramic Matrix Composites

2018 ◽  
Vol 141 (3) ◽  
Author(s):  
Yogesh P. Singh ◽  
Michael J. Presby ◽  
Manigandan Kannan ◽  
Gregory N. Morscher
Keyword(s):  
Damage Detection ◽  
Direct Current ◽  
Ceramic Matrix Composites ◽  
Potential Drop ◽  
Ceramic Matrix ◽  
Image Correlation ◽  
Matrix Composites ◽  
Direct Current Potential Drop ◽  
Current Potential

The method of direct current potential drop (DCPD) can be utilized as an effective and convenient approach for in situ damage detection, and as a nondestructive evaluation technique. We present the results from use of a multiprobe DCPD technique for in situ damage detection in loading of a SiC/SiC composite. It is shown that in three different modes of loading (monotonic, fatigue, and cyclic load–unload), the sensing capabilities of DCPD technique compare well to the techniques of modal acoustic emission (AE) and digital image correlation (DIC). It was also found that DCPD technique provides a far earlier warning of failure under fatigue loading than the other two methods. In addition, we show that strategically placed multiple voltage leads on the specimen surface provide a promising way of qualitatively determining the crack initiation site. Therefore, the use of multiple lead DCPD method, together with other techniques, provides a viable option for sensing damage in ceramic matrix composites (CMCs) with complex geometries, and for applications at higher temperatures.

Damage Monitoring and Analysis of Fiber-Metal Laminates with an Open Hole Using Digital Image Correlation

2017 ◽  
Vol 868 ◽  
pp. 323-327 ◽  
Author(s):  
An Shi Tong ◽  
Li Yang Xie ◽  
Xin Bai ◽  
Ming Li ◽  
Wei Ying Meng
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Tensile Loading ◽  
Surface Strain ◽  
Image Correlation ◽  
Uniaxial Tensile ◽  
Fiber Metal Laminates ◽  
Damage Initiation ◽  
Open Hole ◽  
Fiber Metal

Notched fiber-mental laminates are susceptible to damage. Nowadays, damage detection mainly depends on visual inspection and C scan. But the two methods are limited to the technical skill of the inspectors, causing missed detection or even fault detection. This paper devotes to exploring the DIC monitoring technique to assess of the damage process taking place in notched (open hole) specimens under uniaxial tensile loading. Two-dimensional (2D) Digital Image Correlation (DIC) techniques are employed to obtain full-field surface strain measurements of GLARE3-3/2 and GLARE6-3/2 laminate with an open circular hole under tensile loading. Failure modes,damage initiation and progression of notched fiber-metal laminates are characterized and discussed.

Cluster analysis of acoustic emission signals and tensile properties of carbon/glass fiber–reinforced hybrid composites

2019 ◽  
Vol 18 (5-6) ◽  
pp. 1686-1697 ◽  
Author(s):  
Wen-zheng Zhao ◽  
Wei Zhou
Keyword(s):  
Acoustic Emission ◽  
Digital Image Correlation ◽  
Glass Fiber ◽  
Digital Image ◽  
Hybrid Composites ◽  
Correlation Method ◽  
Tensile Loading ◽  
Image Correlation ◽  
Matrix Cracking ◽  
Woven Composites

Understanding the damage and failure of carbon/glass epoxy hybrid woven composites under tensile loading based on acoustic emission signals is a challenging task in their practical uses. In this study, an approach based on fuzzy c-means algorithm is proposed to process the acoustic emission signals from tensile loading of composites monitored by combining acoustic emission technology and digital image correlation method. The results show that the acoustic emission signals from tensile loading can be divided into three clusters. The three clusters correspond to three kinds of damage modes including matrix cracking, fiber/matrix debonding, delamination, and fiber breakage. By comparing the acoustic characteristics of these classes, a correlation procedure between the clusters and the damage mechanisms observed is proposed. Meanwhile, it can be found that debonding and fiber break signals for glass fiber correspond to a lower frequency range than that for carbon fiber. Moreover, the method combining acoustic emission and digital image correlation can effectively monitor the damage process of the specimen both on the inside and outside, which can provide a reference for the health monitoring of composite structure.

Local Constitutive Behavior of Undermatched Welded Joints in Pipeline Steel Using Digital Image Correlation Technology

2020 ◽  
Vol 142 (5) ◽  
Author(s):  
X. Wu ◽  
J. Shuai ◽  
K. Xu ◽  
Z. Lv
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Welded Joints ◽  
Pipeline Steel ◽  
Image Correlation ◽  
Optical Observations ◽  
Uniaxial Tensile ◽  
Welded Steel ◽  
Steel Joint ◽  
Constitutive Parameters

Abstract Although the identification of local constitutive behaviors is possible based on digital image correlation (DIC), few studies have been reported that characterize the properties of the girth-welded joints of pipeline steel. The DIC technique was used to measure the strain fields of undermatched girth-welded joints of X80 pipeline steel under uniaxial tension in this paper. First, microstructure optical observations and micrometer hardness measurements were used to test the size and hardness of the subregions in the specimens. Second, the local strain data in different regions of the girth-welded joint were obtained via DIC technology, and the stress data were obtained via uniaxial tensile tests. Then, the stress–strain relationships of the weld metal (WM), base metal (BM), and subregions of the heat-affected zone (HAZ) of the girth-welded joints of pipeline steel were obtained. Finally, the constitutive parameters of the Ramberg–Osgood model in the different regions were determined by curve fitting of the strain and stress data. The local yield strength, elastic modulus, and hardening exponent of the welded joints were obtained. The yield stresses of the different subregions of the welded steel joint followed the sequence BM > WM > HAZ, which was consistent with the results of the hardness measurements. The hardening exponents of the different subregions of the welded steel joint followed the sequence HAZ > WM> BM.

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