JEC COMPOSITES MAGAZINE - Issue #142 - September/October 2021 - 42

FEATURE body in white
Fig. 8: Building Block
Approach used for
EADO ET development
Tab.1: Crash results comparison - simulation vs. test
Crash regulations
(according to C-NCAP)
Full width frontal impact
Offset deformable barrier
(ODB) frontal impact
Side impact mobile
deformable barrier (MDB)
els of detail needed to simulate the required
load cases. Given the limited project time
available and the requirement for more than
ten different material cards (combination of
different materials, technologies and grammages),
Forward Engineering classified similar
material cards according to the pre-defined
production process and fibre volume
content, which allowed the team to reduce
the number of tests by keeping the material
cards reasonably accurate and still covering
the variation in technologies.
Secondly, the load conditions of the different
BiW zones, classified as crash relevant,
strength or stiffness-dominated-were analyzed
to assess the level of demand for material
cards for each part and material.
These would then be best described through
the Modular Approach to material characterization
(Copyright FE, Figure 7). Based on
this specific material card development stratTarget
17,5
18
18,5
Simulation
18,46
18,22
19,1
Test
18,37
18,72
17,99
egy,
a full characterization (1A, 2A, 2B) was
carried out for the materials in crash-related
zones, while some post failure assumptions
were made for the less critical material cards
(only 1A or 1A + 2A tested).
On the basis of such a material development,
a wide range of simulations and hardware
tests starting from coupon/plaque level, over
component/sub-system to system/vehicle
level were conducted, known as the Building
Block Approach, to further improve the
predictability on different load cases for the
vehicle, especially for vehicle crash load absorbing
areas. The paralellized building block
approach (Figure 8) with iteration loops
ensured that both the cost and the performance
objectives were met. This was assured
through testing performed on a number of
less expensive specimen, and building a plausible
database at different complexity levels
of the development at the same time.
Design validation
Finally, the designed overall vehicle was validated
by additional FEA simulations and
hardware tests at Changan. While meeting
the targets of stiffness and strength requirements,
the vehicle successfully achieved the
required 5-Star rating according to C-NCAP
regulations. Criteria evaluated full-width
frontal impact, offset deformable barrier
(ODB) frontal impact, and side impact mobile
deformable barrier (MDB). The results
of simulations and crash tests also displayed
good correlation, as shown in Table 1.
During the ODB test, the aluminium frame
acted as the main energy absorption element
while the CFRP body provided the
necessary stiffness to support the aluminium
structure and to protect the occupant
compartment by minimizing the intrusion of
the dash panel. Consequently, the intrusion
in the dash panel was well-controlled and
the occupant compartment structure could
maintain very good structural integrity. The
peak acceleration was below 35g and the
curve correlated well with the CAE simulation
result (Figure 9) thanks to the validated
material cards. Besides this, the main visible
failures were predicted successfully by the
simulations. (Figure 10)
Similar results and behaviour can be observed
from the front crash with a full-width
rigid barrier, which for this vehicle was less
critical than the ODB.
Thanks to the multi-material steel-core concept
and the remaining steel beam in the door
structure, the vehicle absorbs the side impact
energy by deforming within the allowable
limits and preserving its structural integrity.
As observed in Figure 11, the simulation
accurately predicted the regions where damage
would occur on the front and rear door
panels. The difference in the score (simulation
vs. test) is mainly in the rear door upper
area (chest), as the dummy chest was more
heavily compressed than predicted by the
Fig. 9: Acceleration
ODB - simulation vs.
test
42
jec composites magazine / N°
142 September - October 2021
Fig. 10: Comparison of ODB results - simulation
vs. test
JEC COMPOSITES MAGAZINE - Issue #142 - September/October 2021

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