Riassunto analitico
Suspensions are a fundamental component of every car, being it a race car, an off-road car or
a daily-use passenger car. They must provide a uniform wheel-to-ground contact, control the position
of wheels and body with respect to the ground and provide good comfort. These functions have
different importance depending on the class of vehicle being considered, with race cars that have
main requirements on wheel loads consistency and ride height consistency, for tyres and aerodynamic
performance, respectively.
The aforementioned aspects are in great conflict between them, with Aerodynamics calling
for stiffer springs and harder dampers and tyres calling for softer springs and weaker dampers.
Therefore, it becomes fundamental to find the best synthesis between them, to grant to the car both
consistency in ride heights and in wheel loads.
To achieve this goal, racing teams exploit a tool called poster rig, which allows them to define
a combination of springs and dampers’ settings capable of ensuring high performance without the
need of taking the car to the race track. Actually, once the track profile is known (thanks to prior
testing or information provided by the promoter of the competition or by the owner of the track) the
poster rig excites the car with the same spring displacements, upright accelerations and push rod loads
given by the track profile, and by changing springs, anti-roll bars, dampers’ settings and other set up
parameters it’s possible to evaluate which combinations minimize the contact patch load variations.
With the information recorded at the rig, teams go on track to test the most promising set up changes
and to cross check the results obtained during indoor testing.
However, testing at the poster rig has some intrinsic limitations: tyres are neither rolling nor
at running temperature, longitudinal and lateral grip are not replicated, and eventually Ride Dynamics
is not the full Vehicle Dynamics. Its results can be used as a starting point for the definition of the
proper set up for the specific race track, bearing in mind that driver feelings and all the aspects which
are not present during indoor testing might lead to choices different from those made at the rig.
The present thesis introduces a simplified 2-Post Model for a GT3 car, developed starting
from data acquired during tests and races which took place in different circuits. The idea was to build
a tool capable of quickly providing an estimation of the wheel loads developed during a lap around
the track, depending on the chosen configuration of springs and dampers. Even though such a model
has some intrinsic limitations, due to assumptions and simplifications on which it is based, it can be
considered a powerful tool to decide a baseline configuration with which to start the racing weekend
7
on a known track, in order to invest more time on developing areas of the car which cannot be
simulated in advance.
Experience has shown that the choice of springs and dampers’ settings constitutes a major
KPI, heavily influencing the behaviour of the car. Since the time devoted to the definition of their
configuration typically is quite big, having a tool capable of speeding up this choice would be an
important step forward in the economy of a racing weekend.
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Abstract
Suspensions are a fundamental component of every car, being it a race car, an off-road car or
a daily-use passenger car. They must provide a uniform wheel-to-ground contact, control the position
of wheels and body with respect to the ground and provide good comfort. These functions have
different importance depending on the class of vehicle being considered, with race cars that have
main requirements on wheel loads consistency and ride height consistency, for tyres and aerodynamic
performance, respectively.
The aforementioned aspects are in great conflict between them, with Aerodynamics calling
for stiffer springs and harder dampers and tyres calling for softer springs and weaker dampers.
Therefore, it becomes fundamental to find the best synthesis between them, to grant to the car both
consistency in ride heights and in wheel loads.
To achieve this goal, racing teams exploit a tool called poster rig, which allows them to define
a combination of springs and dampers’ settings capable of ensuring high performance without the
need of taking the car to the race track. Actually, once the track profile is known (thanks to prior
testing or information provided by the promoter of the competition or by the owner of the track) the
poster rig excites the car with the same spring displacements, upright accelerations and push rod loads
given by the track profile, and by changing springs, anti-roll bars, dampers’ settings and other set up
parameters it’s possible to evaluate which combinations minimize the contact patch load variations.
With the information recorded at the rig, teams go on track to test the most promising set up changes
and to cross check the results obtained during indoor testing.
However, testing at the poster rig has some intrinsic limitations: tyres are neither rolling nor
at running temperature, longitudinal and lateral grip are not replicated, and eventually Ride Dynamics
is not the full Vehicle Dynamics. Its results can be used as a starting point for the definition of the
proper set up for the specific race track, bearing in mind that driver feelings and all the aspects which
are not present during indoor testing might lead to choices different from those made at the rig.
The present thesis introduces a simplified 2-Post Model for a GT3 car, developed starting
from data acquired during tests and races which took place in different circuits. The idea was to build
a tool capable of quickly providing an estimation of the wheel loads developed during a lap around
the track, depending on the chosen configuration of springs and dampers. Even though such a model
has some intrinsic limitations, due to assumptions and simplifications on which it is based, it can be
considered a powerful tool to decide a baseline configuration with which to start the racing weekend
7
on a known track, in order to invest more time on developing areas of the car which cannot be
simulated in advance.
Experience has shown that the choice of springs and dampers’ settings constitutes a major
KPI, heavily influencing the behaviour of the car. Since the time devoted to the definition of their
configuration typically is quite big, having a tool capable of speeding up this choice would be an
important step forward in the economy of a racing weekend.
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