The Siemens answer: Complete mobility. - Virtual Vehicle

Research into vehiclejtrack interactions
Knowledge of the interactions between rai/way vehicles and their track is a
precondition for further optimisation of the wheeljrail system. The "Vehicle
Oynamics - Rail Applications" group within in the Virtual Vehicle Research Centre
in Graz (Austria) is involved in a project to establish the influences of various
parameters on the dynamic interactions between vehicles and railway tracks and
their consequential effects, making use of vehicles, which, although only virtual,
are very close to reality.
Rg. 1: Computer graphie ofa "virtual rai/way vehiele"
Sourees: Siemens (photo) and Virtual Vehiele (multiple-body simulation. graphie)
The decisive factor in optimising the railway
as a system is to apply a holistic, systematic
view of that system, along with the subsystems
"vehicle" and "track", and the way
they interact through the wheeljrail contact.
The kernel of the wheeljrail contact can be
studied by looking into four facets: "contact
geometry", "adhesion", "wear" and "damage".
In addition to this, the structural dynamic
properties of the wheel sets as weil
as the dynamic properties of the track are
of importance. Allofthis is also associated
with questions regarding the quality of the
track's geometry and the condition of the
track.
By fitting together the specific simulation
Dipl.-Ing.
Bernd Luber
Team Leader ­
Rail Applications
Area Mechanics
Virtual Vehicle Competence Centre, Graz
bemd.luber@V2c2.at
32 RTR 1/2011
models in the area of "rail systems", as
the Graz centre is doing, it becomes possible
to produce conclusions closely reflecting
the reality of the railway as a complete
system. These results can then be applied
right fram the early phase of product development
thraugh to maintenance (Fig. 1).
1 Wheeljrail contact
Effects occur at the point of adhesion between
the wheel and the rail that are relevant
not only for the dynamics of vehicle
movement and the track andjor the damage
phenomena but also for making adjust-
Dr. techno
Martin Rosenberger
Co-Head of
Area Mechanics
Virtual Vehicle Competence Centre, Graz
martin.rosenberger@v2c2.at
ments to traction and braking. The "rail systems"
group in Graz is developing models
for the purpose of recording relevant influences
and visualising them reliably.
It is a fair general statement that the mechanisms
regarded as responsible for the occurrence
of many of the forms of damage
affecting wheels and rails have not yet been
adequately researched. It is possible that
a better understanding of the processes at
play in wheeljrail contact may lead to a reduction
in wear and rolling contact fatigue
(RCF) affecting both wheels and rails. If so,
it will then be possible to lengthen maintenance
intervals and bring down maintenance
costs. At the same time, there will
be improvements in operational safety and
passenger comfort.
1.1 Damage mechanisms
In order to understand the underlying
mechanisms that lead to wear (profile wear,
short-pitched rail corrugations and eccentricities)
and RCF (head checks and herringbone
patterns), it is necessary to know
about the friction processes occurring at
the point of contact, on the one hand, and
the structural dynamics of the vehicle and
the track, on the other hand (Fig. 2).
The effects occurring at the point of adhesion
between wheels and rails are, however,
also of significance for adjusting traction
and breaking. The models already in
use today do not take sufficient account
of them. The adhesion characteristics are
affected by temperature influences, rough-
Dr. techno
Michael Schmeja
Area Manager System
..,o;:",.lYI'•• Design & Optimisation
Head of Interdepartmental
Function RAIL
Virtual Vehicle Competence Centre, Graz
Michael.Schmeja@V2c2.at