Tensile Test for Polymer Plastics with Extreme Large Elongation Using Quad-Camera Digital Image Correlation

Author(s):  
Xin Xie ◽  
Danielle Zeng ◽  
Junrui Li ◽  
Jeffrey Dahl ◽  
Qiancheng Zhao ◽  
...  
2013 ◽  
Vol 749 ◽  
pp. 597-600
Author(s):  
Chao He ◽  
Shi Ming Cui ◽  
Yan Zeng Wu ◽  
Ze Fu Luo ◽  
Qing Yuan Wang

The effect of the mechanical heterogeneity on the global and local tensile properties of laser-arc hybrid welded joints in industrial pure aluminum has been investigated. Digital image correlation method has been used during tensile test for mapping the strain distribution and to determine the local stress-strain curves of FZ and HAZ. The tensile properties of the various regions are very heterogeneous and HAZ is the weakest region because of the strain localizes during tensile test. Finite element technique was used to model the global response of welded joint based on local constitutive properties which could be determined from DIC results.


2015 ◽  
Vol 82 (7) ◽  
Author(s):  
Dominik Lindner ◽  
Florent Mathieu ◽  
François Hild ◽  
Olivier Allix ◽  
Cuong Ha Minh ◽  
...  

This paper presents a coupled experimental/numerical procedure to evaluate triaxiality fields. Such a type of analysis is applied to a tensile test on a thin notched sample made of Ti 6-4 alloy. The experimental data consist of digital images and corresponding load levels, and a commercial code (abaqus) is used in an integrated approach to digital image correlation (DIC). With the proposed procedure, samples with complex shapes can be analyzed independently without having to resort to other tests to calibrate the material parameters of a given constitutive law to evaluate triaxilities. The regularization involved in the integrated DIC (I-DIC) procedure allows the user to deal with experimental imperfections such as cracking of the paint and/or poor quality of the speckle pattern. For the studied material, different hardening postulates are tested up to a level of equivalent plastic strain about three times higher than those achievable in a tensile test on smooth samples. Different finite element (FE) discretizations and model hypotheses (i.e., 2D plane stress and 3D simulations) are compared.


Author(s):  
William Siefert ◽  
James Rule ◽  
Boian Alexandrov ◽  
Mike Buehner ◽  
Jorge A. Penso

Abstract Qualification for weld strength is typically accomplished using cross weld tensile testing. This style of testing only gives the global behavior of the welded joint and limited materials properties, such as elongation at failure and tensile strength of the material where final failure occurs. Qualification for welded structures usually requires the weldment fails in the base metal. Final failure in cross weld tensile tests in the base metal does not provide information about the actual weld metal and heat affected zone properties. There may be weaker points in the microstructure that cannot be identified in a global cross weld tensile test due to being constrained by surrounding microstructures. Additionally, the traditional cross weld tensile test does not quantify how strain accumulates and transfers in the microstructure at various loads. Using Digital Image Correlation (DIC) in combination with tensile testing, local strain of the various microstructures present across the weld was obtained for ferritic to austenitic dissimilar metal welds (DMW), as well as for a typical “matching” ferritic steel filler metal weld with a higher tensile strength than the base metal. This test also showed where and how strain accumulated and transferred during tensile loading of various welded microstructures. Local yield stresses of each region were also obtained. Obtaining such local properties provides insight into design and service limits of welded components in service.


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