Automotive Engineering - September 2022 - 3

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3M, Matrix Engineering Consultants Collaborate to Enhance Performance
of Chassis Bolted Joints
The vehicle electrification trend means chassis designs are evolving. The increasing number of vehicle variants on a modular architecture
can present challenges of how to handle the differences in weight and loading dynamics while utilizing the same or
similar carry-over chassis designs. In a new white paper, 3M and Matrix Engineering Consultants demonstrate how the shear capacity
of critical bolted connections can be enhanced by using 3M™ Friction Shims. Florian Grimm, Global Technical Lead at
3M Friction Solutions, and Jon Ness, Principal Engineer at Matrix Engineering Consultants, discussed their findings with SAE's
Automotive Engineering magazine.
Automotive Engineering: Why is it important
for OEM design engineers to
care about bolted joints?
Jon Ness: Although they appear to be
relatively simple structures, bolted joints
actually play a critical role in the structural
integrity and reliability of an automobile.
In the automobile application,
weight and costs are both critical constraints,
even though the joints are highly
loaded dynamically. The key to
achieving high reliability in dynamically
loaded shear joints is to prevent the
joints from slipping under all loading
conditions. So, that is why engineers
need to pay attention to bolted joints.
Automotive Engineering: Bolted joints
in vehicles aren't uncommon. Why is
your new study relevant?
Florian Grimm: The number of vehicle
variants for a model is increasing - and
especially in battery electric vehicles,
there are multiple models using the same
chassis or 'skateboard' design. These
variants can present challenges of how to
handle differences in weight and loading
dynamics while utilizing the same or similar
carryover chassis design.
One solution can be to increase the
shear capacity of the critical bolted connections.
This can either be done by increasing
the clamp load in the joint using
a stronger bolt or increasing the friction
coefficient at the joint interface; 3M™
Friction Shims are an effective way of
increasing the friction coefficient with
minimal impact to the design as they are
very, very thin, nickel-coated steel substrates
with partially embedded diamonds. When you place
them between two components in a bolted connection, the
diamonds bite into each surface to create a microform fit -
and that leads to much higher friction within this connection.
Automotive Engineering: Your new white paper takes a
deeper dive into the performance of shear loaded bolted
joints using finite element analysis?
AUTOMOTIVE ENGINEERING
Florian Grimm, 3M Global Technical Lead,
Friction Solutions.
Jon Ness: Yes - it is common practice
to model these joints using finite element
analysis, especially in situations
where the load path for the joint is unclear
or where perhaps the slip behavior
of the joint under the load must be
modeled accurately. This paper includes
a case study of a typical automotivechassis
strut bolted joint, where we took
the CAD model and converted it into the
finite element model where the strut
was loaded in shear. And we completed
multiple iterations of the finite element
model, where we varied bolt sizes in one
case and we ran it with and without a
3M™ Friction Shim. And as expected, the
analysis revealed only an incremental
increase in the shear capacity due to
changing the bolt size - say from M10
to M12 - but using a 3M™ Friction Shim
increased a friction coefficient and order
of magnitude.
Jon Ness, Principal Engineer at Matrix
Engineering Consultants
Automotive Engineering: When do you
find that that sort of increase in performance
is needed - particularly in an
existing design?
Florian Grimm: Shims are proven customizable
solution that have been used
in a variety of different applications
across the vehicle. While they have commonly
been used in engine applications
for over 20 years, there's even more
need with electrified powertrains. As we
mentioned before, cars are getting
heavier due to additional batteries, and
examples are chassis applications in subframe
or suspension parts, steering components
or e-motor and battery mounts.
The white paper detailing the collaboration between 3M and
Matrix Engineering Consultants can be downloaded at
3M.com/connections.
Watch the full interview with Florian & Jon.
September 2022 3

http://www.3M.com/connections

Automotive Engineering - September 2022

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