بحث بعنوان Axle Seal Demolding Analysis with Abaqus Explicit

بحث بعنوان
Axle Seal Demolding Analysis with Abaqus Explicit
Maej Masnora Mohamed, Michel S. LeDuc Jr.,b
aFreudenberg-NOK Holdings Inc.,
Malaysia Regional Office,
189 Jalan Tun Razak,
Megan Avenue 1, Suite C-7-2,
50400 Kuala Lumpur, Malaysia
bFreudenberg-NOK Holdings Inc.,
19 Axle Drive
Northfield, NH 03276, United States of America
Abstract
The elastomer axle seal is bonded onto a steelcase which provides
rigidity and lengthen service life. The seal inner lips keep dirt out of the
transmission system while sealing in lubricant that protects the axle.
Demolding analyses using Abaqus Explicit are run to address recurrent hot tears
found at the seal lip area which are caused while the seals are removed from
the mold cavities. Initial iterations show that maximum principal strain, NE,
acting on the affected lip when top mold components are removed, is more
than material break strain at mold temperature, hence the tearing. FEA results
are communicated to mold engineer as design improvement guidelines. Final
iterations using improved mold designs result in 45% reduction of maximum
principal strain acting on the affected lip, bringing the maximum strain on the
lip to slightly below the elastomer break strain.
CONCLUSION
The demolding technique employed at Freudenberg-NOK is continuously
being discussed and revised, even though it has so far provided mold engineers
with good enough insights of the demolding process to troubleshoot most mold
removal issues we face. Abaqus Explicit proves to be superior than Standard
when it comes to solving demolding analyses, as the problem involves large
displacements, large non-linear forces and complex contact between the
elastomer seal and the mold surface. The Marlow model is the most
recommendable material model to use as it provides a good fit with the stressstrain data obtained from uniaxial test, thus effectively predicting mechanical
behavior of elastomer. There is a need to come up with better characterization
of rubber-mold contact as there is a tendency for the rubber to stick to the
mold. Affecting parameters come from both the seal and the mold assembly;
namely the elastomer material used, elastomer mechanical behaviors at
demolding temperature, percentage of curing achieved at the end of molding,
processing aids, mold finishes, use of mold release agents and mold fouling.

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