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Title: Material Models to Study the Bauschinger Effect on an Aluminum Shear Test Specimen

Abstract

Sheet metal forming processes generally involve complex loadings and nonlinear material models. Combinations of drawing, re-drawing and/or reverse drawing operations commonly induce cyclic loads with non-proportional strain paths, leading to Bauschinger effects that can not be predicted by conventional isotropic hardening laws. In order to properly represent this effect, it is also required to accommodate an appropriate kinematic hardening model along with an anisotropic yield function. In this work, two different approaches will be used to predict the Bauschinger effect for an Aluminum shear test specimen: the rate dependent crystal plasticity model and a new combined isotropic/kinematic hardening model based on the two yield surfaces approach (loading and boundary yield surfaces), as recently proposed.

Authors:
;  [1];  [2];  [3]
  1. Centre for Mechanical Technology and Automation, Univ. of Aveiro, 3810-193, Aveiro (Portugal)
  2. Alcoa Technical Center, 100 Technical Dr., PA 15069-0001 (United States)
  3. (Portugal)
Publication Date:
OSTI Identifier:
21061742
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 908; Journal Issue: 1; Conference: NUMIFORM 2007: 9. international conference on numerical methods in industrial forming processes, Porto (Portugal), 17-21 Jun 2007; Other Information: DOI: 10.1063/1.2740889; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ALUMINIUM; ALUMINIUM ALLOYS; ANISOTROPY; CRYSTAL STRUCTURE; CRYSTALS; DRAWING; DYNAMIC LOADS; HARDENING; LOADING; NONLINEAR PROBLEMS; PLASTICITY; SHEAR; SHEETS; STRAINS; SURFACES; TESTING

Citation Formats

Cardoso, Rui P. R., Gracio, Jose J., Yoon, Jeong-Whan, and Centre for Mechanical Technology and Automation, Univ. of Aveiro, 3810-193, Aveiro. Material Models to Study the Bauschinger Effect on an Aluminum Shear Test Specimen. United States: N. p., 2007. Web. doi:10.1063/1.2740889.
Cardoso, Rui P. R., Gracio, Jose J., Yoon, Jeong-Whan, & Centre for Mechanical Technology and Automation, Univ. of Aveiro, 3810-193, Aveiro. Material Models to Study the Bauschinger Effect on an Aluminum Shear Test Specimen. United States. doi:10.1063/1.2740889.
Cardoso, Rui P. R., Gracio, Jose J., Yoon, Jeong-Whan, and Centre for Mechanical Technology and Automation, Univ. of Aveiro, 3810-193, Aveiro. Thu . "Material Models to Study the Bauschinger Effect on an Aluminum Shear Test Specimen". United States. doi:10.1063/1.2740889.
@article{osti_21061742,
title = {Material Models to Study the Bauschinger Effect on an Aluminum Shear Test Specimen},
author = {Cardoso, Rui P. R. and Gracio, Jose J. and Yoon, Jeong-Whan and Centre for Mechanical Technology and Automation, Univ. of Aveiro, 3810-193, Aveiro},
abstractNote = {Sheet metal forming processes generally involve complex loadings and nonlinear material models. Combinations of drawing, re-drawing and/or reverse drawing operations commonly induce cyclic loads with non-proportional strain paths, leading to Bauschinger effects that can not be predicted by conventional isotropic hardening laws. In order to properly represent this effect, it is also required to accommodate an appropriate kinematic hardening model along with an anisotropic yield function. In this work, two different approaches will be used to predict the Bauschinger effect for an Aluminum shear test specimen: the rate dependent crystal plasticity model and a new combined isotropic/kinematic hardening model based on the two yield surfaces approach (loading and boundary yield surfaces), as recently proposed.},
doi = {10.1063/1.2740889},
journal = {AIP Conference Proceedings},
number = 1,
volume = 908,
place = {United States},
year = {Thu May 17 00:00:00 EDT 2007},
month = {Thu May 17 00:00:00 EDT 2007}
}
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  • Current experimental methods are influenced by the end effects that cause non-uniform strain rates in the gauge section and material flow within the grips. A series of tension tests and finite element models confirm this for an Al-5083 alloy. Both the tests and the finite element simulations predict that the actual strain rate begins at about 60 percent of the desired strain rate and increases gradually with strain. Material flow from the grips into the gauge effectively ``slows`` the strain rate at the initial stages of the test. As the test proceeds thinning of the gauge section occurs and mostmore » of the strain occurs in the gauge section due to the relative cross-sectional areas of the grip and gauge section. Testing and models were also run comparing specimens with and without alignment holes in the grips. It was shown that alignment holes increase flow from the grips and thus introduce additional error in the tests. Further modeling was performed to evaluate the improved accuracy of specimens with increased length-to-width ratios. This work showed that a specimen with 50% reduction in the standard gauge width and double the standard gauge length (4:1 increase in length-to-width ratio) gave strain rates within 10% of the desired value throughout the test.« less
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