Press-Hardened and Roll-Formed Lightweight Bumpers in Steels with Enhanced Strength

-Bumpers protect the BIW and external attributes in low speed collisions and contribute to crash safety in high speed collisions (transfer loads to the BIW).

-They are continuously improved through implementation of materials with enhanced strength,new design features, new manufacturing processes, reduction of number of components andreduction of package space.

Objectives:
-Reduce weight of bumpers with roll-formed beams.
-Manage high speed crash w/o rupture of materials or welds.
-Fulfill world wide low speed crash requirements.
-Investigate new materials with higher strength.

Solution:
-Beam section with modularity possibility and press-hardened crash boxes.

Simulation set- - up
-Three point bending.   

Variables
-Dimensional variations.
-Automatic optimization.

M- - profile
-10.4% higher energy
absorption / mass unit
than benchmark beam.

F ront bumper:
-Cross beam 1200 MPa 1.2 mm.
-Crash boxes PH 1200 MPa 1.2 mm.
- Weight 6.37 kg = - - 13%  (compared to benchmark bumper). 

Modularized:
Section depth increased by 10 mm.

Objectives:
-Reduce the necessary package space for rear bumpers.
-Manage high speed crash without rupture of materials or welds.
-Fulfill world wide low speed crash requirements.
-Investigate new press hardening materials with higher strength.

Solution:
-Implement patch technology on press hardened beam with deformable section.

Innovation:
-Patch technology – additional material only where
needed.
-For improved high speed crash performance.

Front  bumper , press- - hardened beam and  crash boxes

A beam in press-hardened un-coated quality with ~2000 MPa tensile strength isgood for crash applications, as are crash boxes in press-hardened three-layered 1200 MPa material.

Using these materials can reduce the weight of a present front bumper by ~15%.

Front b b umper , roll- - formed beam , press- - hardened crash boxes

A beam with roll-formed M-profile in 1200 MPa is 10.4% lighter than benchmark roll-formed beam.
The M-profile is possible to modularize, in order to increase the bending stiffness and/or adapt to fit
with the package requirement.
A beam with M-profile in 1200 MPa material and crash boxes in press-hardened 1200 MPa material
is 13% lighter than benchmark bumper and still deliver superior crash performance.

R ear b b umper , press- - hardened beam with patch
A beam in press-hardened un-coated quality with ~2000 MPa tensile strength.
The bumper fulfills world-wide low speed crash requirements.
The bumper beam only experiences minor material failure in high speed impacts.
The patch, including heat-affected zones, remain completely intact.