Prediction of Strain Path Changing Effect on Forming Limits of AA 6111-T4 Based on A Shear Ductile Fracture Criterion

Strain path changing is a phenomenon in the stamping of complex panels or multiple-step stamping processes. In this study, the influence of the strain path changing effect was investigated and assessed for an aluminum alloy of 6111-T4 with a shear ductile fracture criterion. Plastic deformation of t...

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Main Authors: Silin Luo, Gang Yang, Yanshan Lou, Yongqian Xu
Format: Article
Language:English
Published: MDPI AG 2021-03-01
Series:Metals
Subjects:
Online Access:https://www.mdpi.com/2075-4701/11/4/546
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spelling doaj-f0c0a2fc0b4c4c8a8a5e4d5ff6ee7f132021-03-27T00:08:30ZengMDPI AGMetals2075-47012021-03-011154654610.3390/met11040546Prediction of Strain Path Changing Effect on Forming Limits of AA 6111-T4 Based on A Shear Ductile Fracture CriterionSilin Luo0Gang Yang1Yanshan Lou2Yongqian Xu3School of Mechatronics and Mold Engineering, Taizhou Vocational College of Science & Technology, Taizhou 318020, Zhejiang, ChinaSchool of Mechatronics and Mold Engineering, Taizhou Vocational College of Science & Technology, Taizhou 318020, Zhejiang, ChinaSchool of Mechanical Engineering, Xi’an Jiaotong University, 28 Xianning West Road, Xi’an 710049, Shaanxi, ChinaState Key Laboratory of High-Performance Complex Manufacturing, Central South University, Changsha 410083, Hunan, ChinaStrain path changing is a phenomenon in the stamping of complex panels or multiple-step stamping processes. In this study, the influence of the strain path changing effect was investigated and assessed for an aluminum alloy of 6111-T4 with a shear ductile fracture criterion. Plastic deformation of the alloy was modeled by an anisotropic Drucker yield function with the assumption of normal anisotropy. Then the shear ductile fracture criterion was calibrated by the fracture strains at uniaxial tension, plane strain tension and equibiaxial tension under proportional loading conditions. The calibrated fracture criterion was utilized to predict forming limit curves (FLCs) of the alloy stretched under bilinear strain paths. The analyzed bilinear strain paths included biaxial tension after uniaxial tension, plane strain tension and equibiaxial tension. The predicted FLCs of bilinear strain paths were compared with experimental results. The comparison showed that the shear ductile fracture criterion could reasonably describe the effect of strain path changing on FLCs, but its accuracy was poor for some bilinear paths, such as uniaxial tension followed by equibiaxial tension and equibiaxial tension followed by plane strain tension. Kinematic hardening is suggested to substitute the isotropic hardening assumption for better prediction of FLCs with strain path changing effect.https://www.mdpi.com/2075-4701/11/4/546shear ductile fractureforming limit curvestrain path changingsheet metal forming
collection DOAJ
language English
format Article
sources DOAJ
author Silin Luo
Gang Yang
Yanshan Lou
Yongqian Xu
spellingShingle Silin Luo
Gang Yang
Yanshan Lou
Yongqian Xu
Prediction of Strain Path Changing Effect on Forming Limits of AA 6111-T4 Based on A Shear Ductile Fracture Criterion
Metals
shear ductile fracture
forming limit curve
strain path changing
sheet metal forming
author_facet Silin Luo
Gang Yang
Yanshan Lou
Yongqian Xu
author_sort Silin Luo
title Prediction of Strain Path Changing Effect on Forming Limits of AA 6111-T4 Based on A Shear Ductile Fracture Criterion
title_short Prediction of Strain Path Changing Effect on Forming Limits of AA 6111-T4 Based on A Shear Ductile Fracture Criterion
title_full Prediction of Strain Path Changing Effect on Forming Limits of AA 6111-T4 Based on A Shear Ductile Fracture Criterion
title_fullStr Prediction of Strain Path Changing Effect on Forming Limits of AA 6111-T4 Based on A Shear Ductile Fracture Criterion
title_full_unstemmed Prediction of Strain Path Changing Effect on Forming Limits of AA 6111-T4 Based on A Shear Ductile Fracture Criterion
title_sort prediction of strain path changing effect on forming limits of aa 6111-t4 based on a shear ductile fracture criterion
publisher MDPI AG
series Metals
issn 2075-4701
publishDate 2021-03-01
description Strain path changing is a phenomenon in the stamping of complex panels or multiple-step stamping processes. In this study, the influence of the strain path changing effect was investigated and assessed for an aluminum alloy of 6111-T4 with a shear ductile fracture criterion. Plastic deformation of the alloy was modeled by an anisotropic Drucker yield function with the assumption of normal anisotropy. Then the shear ductile fracture criterion was calibrated by the fracture strains at uniaxial tension, plane strain tension and equibiaxial tension under proportional loading conditions. The calibrated fracture criterion was utilized to predict forming limit curves (FLCs) of the alloy stretched under bilinear strain paths. The analyzed bilinear strain paths included biaxial tension after uniaxial tension, plane strain tension and equibiaxial tension. The predicted FLCs of bilinear strain paths were compared with experimental results. The comparison showed that the shear ductile fracture criterion could reasonably describe the effect of strain path changing on FLCs, but its accuracy was poor for some bilinear paths, such as uniaxial tension followed by equibiaxial tension and equibiaxial tension followed by plane strain tension. Kinematic hardening is suggested to substitute the isotropic hardening assumption for better prediction of FLCs with strain path changing effect.
topic shear ductile fracture
forming limit curve
strain path changing
sheet metal forming
url https://www.mdpi.com/2075-4701/11/4/546
work_keys_str_mv AT silinluo predictionofstrainpathchangingeffectonforminglimitsofaa6111t4basedonashearductilefracturecriterion
AT gangyang predictionofstrainpathchangingeffectonforminglimitsofaa6111t4basedonashearductilefracturecriterion
AT yanshanlou predictionofstrainpathchangingeffectonforminglimitsofaa6111t4basedonashearductilefracturecriterion
AT yongqianxu predictionofstrainpathchangingeffectonforminglimitsofaa6111t4basedonashearductilefracturecriterion
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