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Evaluation of Bendability of Advanced High Strength Steels

Kim, Kyungbo
http://rave.ohiolink.edu/etdc/view?acc_num=osu1244008200

Abstract Details

2009, Master of Science, Ohio State University, Mechanical Engineering.
To improve crash worthiness and fuel economy, the auto industry is using increasingly Advanced High Strength Steels (AHSS) for automotive body structure components. However, due to the limited formability of AHSS compared to conventional steels, unexpected cracks usually in bending area or stretched blank edge are more often observed during stamping of AHSS.The major objective of this study is to predict bending failures in forming AHSS. For this purpose, Stretch Bending test (SBT) and Wedge Bending test (WBT) were used and were simulated by Finite Element (FE) simulation to predict the bending failure. In this study, fracture studies for stamping and basic bending theory are introduced. Several different type bending tests and their evaluation of bendability with AHSS in literature are discussed in details. In addition, fracture criteria used in predicting fracture are described. Validity of the fracture criteria is determined in comparing with experiment data of Deep Drawing test and Bore-Expanding test from literature. FE simulation of Stretch Bending test is analyzed using a commercial software, DEFROM-2D, to compare with experimental result from literature. In this test, several punch radii were simulated to evaluate bendability of AHSS. In order to obtain fracture criteria in bending AHSS, Air Bending test, so called Wedge Bending test (WBT), was also used as the second method to evaluate a formability of AHSS. Material properties of AHSS from tensile test and viscous pressure bulge test were obtained. Both material data are used for FE simulation of Wedge Bending test to investigate which one shows better correlation with experimental data. 3-D tensile test simulation was conducted to obtain critical damage value. Preliminary Finite Element simulations for Wedge Bending test were conducted. Results of wedge bending simulations were compared by using different material data (e.g. plastic, elasto-plastic, tensile data, bulge data) and coefficient of frictions. The comparison between experiments and simulations were made and summarized.
Taylan Altan (Advisor)
Gary Kinzel (Committee Member)
Mechanical Engineering

Recommended Citations

Citations

  • Kim, K. (2009). Evaluation of Bendability of Advanced High Strength Steels [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1244008200

    APA Style (7th edition)

  • Kim, Kyungbo. Evaluation of Bendability of Advanced High Strength Steels. 2009. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1244008200.

    MLA Style (8th edition)

  • Kim, Kyungbo. "Evaluation of Bendability of Advanced High Strength Steels." Master's thesis, Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1244008200

    Chicago Manual of Style (17th edition)

osu1244008200
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© 2009, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.