Energy Absorption Behavior and Application of Thin-walled Box Structure with Higher Strength in Ridgelines

To overcome some drawbacks of using AHSS (Advanced High Strength Steel) in vehicle weight reduction, like brittleness, spot weld HAZ (Heat Affected Zone) softening and high cost, a new ridgeline strengthening technology was introduced and applied to the thin-walled structure in this paper. The energy absorption mechanism of thin-walled box structure with selective strengthened ridgelines under axial compressing load was discussed in first section. After this, the formulas of mean crushing force and corresponding energy absorption for square tube were theoretically discussed. To demonstrate prediction capabilities of formulas, a set of FE simulations of square tubes were conducted. Simulation results show that energy absorption capacity of square tube under quasi-static axial crushing load is dramatically improved by selectively strengthening their ridgelines. Finally, the ridgeline strengthening technology was applied to front bumper subsystem made of mild steel and its energy absorption capacity was compared with AHSS front bumper subsystem. From the comparison, it was concluded that the thin-walled box structure with selective strengthened ridgelines can replace the AHSS and could be widely used in the vehicle body structure.