Date of Award


Publication Type


Degree Name



Mechanical, Automotive, and Materials Engineering


Axial crush, Boron-steel, High strain rate, LS-DYNA, Press hardening


D. Green


W. Altenhof



Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.


This thesis investigates the response of 1500 MPa and 2000 MPa press hardening steel (PHS) in a dynamic crushing scenario. The work involves creating numerical models to simulate tailored channel sections. The zones of different hardness are created using the tailored hot stamping process (THS), where a heated die set is used to quench an austenitized blank to produce parts with zones of differentiating hardness.

The 1500 MPa PHS was quenched using a die heated to different temperatures to produce a range of microstructures (225 HV to 473 HV) as well as the 2000 MPa PHS (297 HV to 574 HV). The as quenched specimens were characterized at strain rates of 0.003 s-1 (quasi-static), 0.1 s-1 (quasi-static), 100 s-1 (intermediate rate) and 1500 s-1 (high rate).

The PHS exhibited strain rate-sensitive behavior that was logarithmic in nature. The fully quenched1500 MPa PHS exhibited an ultimate tensile strength that varied from 1502 MPa at a strain rate of 0.003 s-1to 2003 MPa at a strain rate of 1500 s-1. The 2000 MPa PHS exhibited a similar increase in strength with respect to strain rate.

The materials were tested for their ability to be spot welded so that the numerical models had accurate spot weld parameters. Both materials were welded using the same weld settings and produced average weld nugget sizes of 5.8 mm (1500 MPa PHS) and 5.3 mm (2000 MPa PHS).

Numerical models were developed using data from the uniaxial tensile testing and were simulated at different impact speeds. Axial crushing of tailored and fully hardened channels were simulated to compare the effects of tailoring PHS. The tailored and fully hardened channels absorbed similar amounts of energy. The tailored 1500 MPa PHS absorbed 4.84 kJ and 4.88 kJ for the tailored and fully hardened models. Similarly, the 2000 MPa PHS tailored and fully hardened models absorbed 4.92 kJ and 4.98 kJ, respectively. Although the absorbed energies are comparable, the tailored channels had a lower average impact force. The tailored channels also had more localized crushing, while the fully hardened channels deformed in several sections along their length.