Paint-bake effect on the plasticity and fracture of pre-strained aluminum 6451 sheets
Name
986241138-MIT.pdf
Description
Full printable version
Size
4.66 MB
Format
Adobe PDF
Checksum (MD5)
edc3cfd0e47906febf96744e05a4f5f8
Author(s)
Abi Akl, Rami
Advisor(s)
Tomasz Wierzbicki.
Date Issued
2017
Publisher
Massachusetts Institute of Technology
Abstract
In automotive engineering, sheet metal components are subject to a 20 min heat treatment at 180°C during paint baking. This process may significantly alter the mechanical properties of 6000-series aluminum alloys through artificial ageing. Here, a comprehensive experimental program is carried out to characterize the anisotropic plasticity and the fracture initiation in prestrained artificially-aged aluminum 6451 sheets. It is found that the combination of pre-straining up to 5% strain and heat treatment mainly changes the material's strain hardening behavior and the stress-state sensitivity of its fracture response. The material parameters of the Yld2000-2d plasticity model with combined Swift-Voce hardening are identified for four distinct materials from uniaxial tension and shear experiments. The corresponding Hosford-Coulomb fracture model parameters are determined from smiley shear, V-bending and punch experiments. As an important byproduct of the research, the Yld2000-2d and Hosford-Coulomb models are successfully validated for all four materials through notched and central hole tension experiments. Simple empirical expressions are also provided to estimate the material properties as a function of the prestrain in engineering practice.
Description
Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2017.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 54-58).
Subjects
Mechanical Engineering.
MIT Department
Massachusetts Institute of Technology. Department of Mechanical Engineering
Terms of Use
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