The wall thickness for each design profile is adjusted so the weight of the Docol 1700M sill beam is the same as the 6082 T6 aluminum sill beam.
The force vs. displacement simulations show that an AHSS steel cross section must have some sort of rib to work properly. Therefore, all these profiles have some sort of inner structure. To try to keep fabricating costs and complexity down, many simulations have been done using square-shaped tubes welded together.
The welded square tube approach seems to work, but the abutting ribs are doubly thick. And, according to the simulations, the thickness of the outer shell of the profile is more important than the thickness of the ribs.
SSAB has determined which profile — with single-wall ribs — allows for thicker outer walls and delivers a crash performance that is similar to that of an aluminum beam, with the weights being the same for both materials.
Would making an energy-absorbing sill/rocker beam from Docol 1700M AHSS withstand crash deformation without cracking? Initial Docol prototypes show that it can. However, all these square-tube profiles require some type of welding and SSAB needs to perform more testing to determine if the beam’s welds ductile enough to handle deformation without cracking.