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Formability Evaluation of Tailor Welded Blanks (TWBs)

Singhal, Hitansh
http://rave.ohiolink.edu/etdc/view?acc_num=osu1594916942734335

Abstract Details

2020, Master of Science, Ohio State University, Mechanical Engineering.
Sheet metal forming or stamping is the process of plastically deforming sheet blanks into a complex-shaped part, usually without significant change in sheet thickness and surface characteristics. As the problem of climate change is becoming more prominent, the emission standards are becoming more stringent for automobiles. This has driven automotive companies towards light weighting while maintaining the structural integrity of the vehicle. Tailor Welded Blanks (TWBs) have been introduced in the automotive industry to aid in reducing the weight while maintaining the structural performance of stamped parts. Laser welding is the most conventional method for developing TWB. The mechanical behavior of tailor-welded blanks differs from the base materials (materials being welded together) due to the welding. Therefore, comprehensive understanding of deformation behavior and formability of TWBs is essential. The objective of this study is to develop a practical methodology for evaluating the formability of TWBs. This study focuses on TWBs with sheets of same thickness on both sides of weld. In this study, same thickness welded blank (1.2 mm to 1.2 mm) of Galvannealed Draw Quality Aluminium Killed (GNDQAK) steel is evaluated using the tensile test, limiting dome height test, viscous pressure bulge test and plane strain loading condition. Mechanical properties of the material is obtained through the tensile test. The hardening curve for the weld zone and heat affected zone (HAZ) is approximated by comparing the hardness of these zones compared to the base material. Numerical models are developed to simulate material behavior in each of these tests. To improve the simulation accuracy, various material models for the base material, the HAZ, and the weld zone are considered. The most accurate model has been used for simulating the behavior of the welded blank in the hat bending and square cup drawing process. Tensile test experiments of the monolithic and welded coupons are compared in terms of uniform elongation and ultimate tensile strength. Results show that welding does not influence the formability of the material when the part is subjected to uniaxial loading condition. Simulation of the tensile test could predict the formability of the material within 2% variation. Dome test results indicate that for this specific material and weld quality, welding does not significantly affect the formability. However, accurate strain analysis close to the weld line showed that the weld and HAZ influence the loading condition and the strain path. In the monolithic material, the strain path at the center of the dome is equal biaxial while for the welded sample, it moves toward plane strain. This can be described as a result of stronger weld and heat affected zone compared to the base material.
Taylan Altan (Advisor)
Yannis Korkolis (Committee Member)
132 p.
Aerospace Engineering; Industrial Engineering; Mechanical Engineering
Stamping; Sheet Metal Forming; Tailor Welded Blanks; Formability; Manufacturing; Microhardness; Tensile Tests; Finite Element Analysis; PAM-STAMP; DEFORM; Frictionless Dome Test; Viscous Pressure Bulge Test

Recommended Citations

Citations

  • Singhal, H. (2020). Formability Evaluation of Tailor Welded Blanks (TWBs) [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1594916942734335

    APA Style (7th edition)

  • Singhal, Hitansh. Formability Evaluation of Tailor Welded Blanks (TWBs). 2020. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1594916942734335.

    MLA Style (8th edition)

  • Singhal, Hitansh. "Formability Evaluation of Tailor Welded Blanks (TWBs)." Master's thesis, Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1594916942734335

    Chicago Manual of Style (17th edition)

osu1594916942734335
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