Automotive Engineering - September 2024 - 28

BLAZER EV
IS A
STEELMATERIALS
FEATURE
INTENSIVE
SHOWCASE
Frontal and side impact loads are uniformly transferred into
the RESS's transverse cross members that are bordered with
longitudinal 'ski rails.' Eiliat said the extruded aluminum rockers
enable a uniform transfer of about 30% side-impact loads
into the ski rails.
Bolstering the B-pillars
In her presentation, Eiliat revealed the Blazer EV's body-inwhite
bending stiffness to be 25.4 Hz as measured by GM.
The body's torsional stiffness increases as a function of the
RESS pack. The 10-module battery pack has five bays (space
between crossmembers where the cell modules reside),
while the 12-module RESS has six bays. " As your battery gets
bigger and the roof structure gets stronger and stiffer, your
stiffness numbers go up, " she said.
For the GDIS conference, GM brought a Blazer EV white
body and RESS for display. Both properties were closely examined,
photographed, and measured by attendees
throughout the event. Of particular focus was the impactcritical
B-pillar, constructed in Gen-3 AHSS.
" We decided to use Gen-3 to reduce mass with equivalent
performance in IIHS 2.0 and roof crush [testing], " Eiliat noted.
" We save on cost using Gen-3 steel. To facilitate this application,
Two Part Adhesive with
LOW THERMAL RESISTANCE
EP30TC Epoxy Passes NASA Low Outgassing Tests
Exceptionally low thermal resistance
7-10 x 10-6
K*m2
/W
Superb thermal conductivity
18-20 BTU*in/ft2
*hr*°F
Ultra thin bond lines
5-15 microns
To minimize intrusion into the battery space during the front crash
event, the integrated battery structure is utilized to manage transfer of
about 30% of the load, according to Hoda Eiliat. Note the Cradle Bolt
Stabilizer shear plate, which attaches body, cradle and RESS, provides
secondary shear and stabilizes load transfer.
we created a unique material spec, GMW17627, which remains
an industry benchmark. We use unique forming processes that
compensates for springback while adding stiffness. We also
have a specific welding schedule. "
The GMW17627 specification, titled " Retained Austenite
Bearing Advanced High Strength Sheet Steel, " was published
in 2018. It covers the requirements for continuous cast, cold
rolled, retained austenite bearing sheet steel with specified
minimum tensile strengths from 690 MPa to 1180 MPa.
This specification applies to uncoated and coated retained
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www.masterbond.com
28 September 2024
austenite-bearing advanced high-strength steels that rely on
one or more induced plasticity mechanisms to achieve enhanced
combinations of strength and ductility relative to
high-strength steels. Typical applications include body panels,
body structure members, and reinforcements for enhanced
strength and vehicle impact performance.
Highlighting the joining strategies employed by GM at its
Ramos, Mexico, plant, Eiliat said the Blazer EV body features
roughly 6,000 resistance spot welds. There are over four linear
meters (13.1 ft) of laser brazing between the vehicle's roof panel
and bodyside outer. The lower body structure is MIG welded.
Structural adhesives are used in the upper section. The aluminum
side rails attach to the steel body structure using brackets,
rivets, and are isolated with adhesives and tapes.
AUTOMOTIVE ENGINEERING
Blazer EV
Body Structures Front and Rear Loading Topology
Top View
Blazer EV Structural Enablers
Load Management Strategy utilizing a Structurally Integrated Battery Tray
To minimize the intrusion into the battery space during the front crash event, an integrated battery structure can b
utilized to manage transfer of the load (~ 30%).
Body and integrated RESS are engineered to handle front, rear and side
impact loads.
Bottom View
16
Cradle Bolt Stabilizer (Shear Plate) which attaches Body, Cradle and RESS; provides secondary shear and stabilizes l
transfer.
Cradle Bolt Stabilizer
Full Flat Barrier
Engagement
BOTH IMAGES: CHEVROLET

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Automotive Engineering - September 2024

Table of Contents for the Digital Edition of Automotive Engineering - September 2024