Measuring true stress–strain curves of cylindrical bar samples with mirror‐assisted multi‐view digital image correlation

Strain ◽  
2021 ◽  
Author(s):  
Bin Chen ◽  
Bing Pan
2019 ◽  
Vol 2019 ◽  
pp. 1-18
Author(s):  
Bo Xu ◽  
Junwu Xia ◽  
Renwei Ma ◽  
Jian Wang ◽  
Xiaomiao Chen ◽  
...  

The true stress-strain curve is the critical method to describe the practical material mechanical performance and the essential precondition to develop the advanced numerical simulation. Experimental, analytical, and numerical procedures were performed in present research to investigate the true stress-strain curves of flat and corner regions of the cold-formed channel section. The coupon tests with the 3D digital image correlation system were conducted on flat and corner specimens to directly obtain the true stress-strain curves. The experimental results indicate that the tensile secondary-hardening phenomenon at the plastic strain stage was observed in the true stress-strain curves of flat coupons, and initial strain hardening behavior was produced in that of corner coupons. Flat region exhibits a significant improvement of true ultimate strength compared to the engineering value. The stress status of the corner region is developed to ultimate strength at the early strain phase and exhibits a slight increase compared with the nominal values at the plastic phase. Cold-rolling action limits the ductility performance of the corner region, which highly restrains the tensile strain hardening at the plastic condition. Thus, the true yielding strength of the corner region is obviously higher, but the true ultimate strength is significantly lower than that of the flat region. Together with the optical measuring results, a trilinear model with two-stage strain hardening and a simplified trilinear models were established for describing the true stress-strain curves of flat and corner regions, respectively. The load-displacement curves from numerical simulations fit very well with those of coupon tests, which validate the reliability of the optic measurement and the dependability of the simplified constitutive models.


2020 ◽  
Vol 55 (3-4) ◽  
pp. 99-108 ◽  
Author(s):  
Yunlu Zhang ◽  
Sreekar Karnati ◽  
Tan Pan ◽  
Frank Liou

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.


2007 ◽  
Vol 353-358 ◽  
pp. 563-566
Author(s):  
Qin Zhi Fang ◽  
Tie Jun Wang ◽  
Hui Min Li

Large deformation performances of polycarbonate (PC) and PC/ABS (Acrylonitrile Butadiene Styrene) have been investigated experimentally in this paper. The displacement fields of these polymers are measured with a system based on digital image correlation (DIC) method. The variations of strains during tension are measured and the true stress-strain curves are presented. For these materials, it is observed that the contraction in thickness is larger than that in width during tension. No obvious stress softening is observed in the true stress-strain curves. The true stress-strain curves can be fitted well with three-stage model.


2017 ◽  
Vol 2017.92 (0) ◽  
pp. P078
Author(s):  
Keita Suzuki ◽  
Makoto Uchida ◽  
Yoshihisa Kaneko ◽  
Dai Okumura ◽  
Hiro Tanaka ◽  
...  

2018 ◽  
Vol 46 (5) ◽  
pp. 20160487 ◽  
Author(s):  
Ranjitha Rajagopal ◽  
Sameer Sharma ◽  
Radhakrishna G. Pillai ◽  
Sankara J. Subramanian

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